1. UNIT 1: CARDIOVASCULAR PATHOLOGY
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MODULE: CLINICAL PATHOLOGY
UNIT 1 - The Cardiovascular System
By OKINDA, B, Carey Francis
September 2014
OUTLINE
Topic Sub Topics Hours
1. Introduction to
CVS Pathology
Review of Anatomy and Physiology
Pathophysiology of Cardiovascular Disease
Investigations in Cardiovascular Disorders
2
2. The Heart Congenital Disorders 1
Cardiac Failure 2
Ischaemic Heart Disease 1
Valvular Heart Disease 1
Acute Rheumatic Fever and Rheumatic Heart Disease 1
Myocardial and Pericardial Disorders 1
3. Arteries Aneurysms 1
Hypertension and Hypertensive Heart Disease 1
Atheroma/atherosclerosis and Arteriosclerosis 1
4. Veins DVT and PE 1
Varicosities and Haemorrhoids 1
Tumours of Blood Vessels 1
TOTAL 15
Lesson 1: Introduction to Pathology of the Cardiovascular System
Learning Outcomes
At the end of the lesson the learner shall be able to: -
1. Describe the anatomy and physiology of the cardiovascular system
2. Describe mechanisms of cardiovascular disease
3. Discuss investigations in cardiovascular disease
1.0.INTRODUCTION
Cardiovascular pathology is the study of causes and effects of disease on the
cardiovascular system. It comprises the heart and blood vessels (arteries, veins and the
capillaries).
2.0.THE HEART
The function of the heart is to pump sufficient oxygenated blood containing nutrients,
metabolites and hormones to meet the moment to moment metabolic needs and
preserve a constant internal milieu. The heart has three muscles layers - endocardium
(inner muscles of the heart, myocardium (provides contractile force to push blood)
and pericardium (outer covering). The heart has 4 valves namely the aortic,
pulmonary, tricuspid and the mitral valves. Heart muscle has two essential
characteristics of contractility and rythymicity. The conducting system contains
specialized cells for initiation and transmission of signals in a co-coordinated manner. It
comprises the Sino-atrial node (SAN), the atrio-ventricular node (AVN), the Purkinje
tissues (fibres) and the bundle of His. Physiological function of the heart is maintained

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by healthy muscles, efficient valves, the conducting system and co-ordination of chambers
and normal peripheral resistance
Diagram 1.1: Normal Heart
Functioning of the Heart
The heart has three major types of cardiac muscle namely the atrial, ventricular and
the specialized excitatory and conductive muscles. The heart muscle is organized in
two syncytium with the many cells connected in series with intercalated discs with
specialized structures such as fascia adherens (mechanical links), mascula adherens
/desmosome (lattice structure and site for cytoplasmic filaments) and gap junction
(makes the adjacent cells loose and is permeable to ions). This arrangement facilitates
the all or nothing principle.
The Cardiac Cycle
The cardiac cycle comprises of
 Phase I – Atrial Contraction - period of rapid refilling of ventricles in the first 1/3 of
diastole, blood moves slowly into the ventricles in the middle of 1/3 of diastole and
atrial contraction pushes more blood into the ventricles (20 – 30% of ventricular
refilling) in the last 1/3 of diastole.
 Phase II – isovolumic ventricular (isometric) contraction - emptying ventricles during
the beginning of ventricular contraction when no emptying takes place hence the
name isovolumic or isometric (i.e. is there is no increase in tension of muscle but no
shortening of muscle fibres)
 Phase III – ventricular systole – period of ejection with ventricular systole when there
is fast and slow ejection of blood. Left ventricular pressure rises slightly above 80
mmHg and right ventricular pressure rises slightly above 8 mmHg forcing open the
mitral and tricuspid valves respectively; this is fast ejection that accounts for 70% of
ventricular emptying. There is the period of slow ejection that lasts the last 2/3 of
systole.

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 Phase IV – period of isovolumic ventricular (isometric) relaxation- ventricular
relaxation begins allowing ventricular pressure to fall. Increased pressure in the
distended arteries pushes blood back towards the ventricles closing the aortic and
pulmonary valves. The ventricular muscles contract but the ventricular volume stays
– isometric relaxation.
 Phase V – ventricular diastole relaxation (period of ventricular diastole relaxation
overlaps with atrial contraction.
3.0.CARDIAC OUTPUT
The normal cardiac output for young healthy male adult is 4 – 8 litres/minute (average
5.6 litres/min) with females at 10% less. Five basic mechanisms controlling cardiac
output include heart rate, ventricular filling pressure, ventricular distensibility,
systemic vascular resistance and ventricular contractility. Cardiac output (CO) =
Heart rate (HR) x Stroke volume (SV) of the left ventricle
The Stroke volume
Stroke volume is the diastolic volume of the ventricle minus the volume of blood in the
ventricle at the end of systole. Stroke volume output is the amount of blood emptied by
the ventricles during systole (usually 70 mls). The Cardiac Index (CI) is the cardiac
output per square metre of body surface area. The normal is 3.0 litres/minute and
changes with age.
Ejection Fraction
End-diastolic volume is the volume of blood in the ventricles at the end of diastole
when the filling of ventricles increases volume of each ventricle to 120 – 130 mls while
the End-systole volume is the blood remaining in the ventricles at the end of systole
(usually 50 – 70 mls).
Ejection Fraction = 70 x 100 = 58.3% (60%)
120
4.0.THE LAWS
1. Poiseulle’s Law Blood flow = Pressure x diameter of blood vessel
Length of vessel x viscosity of blood
2. Starling’s Law – increase in dilatation leads to increased filling, contraction and stroke
volume
3. Frank-Starling – within physiological limits, the heart pumps all the blood that comes to
it without allowing excessive damming of blood in the veins. The greater the heart is
filled during diastole, the greater will be the amount of blood pumped into the aorta.
4. Laplaces Law – the circumferential force tending to stretch the muscle fibres in the
vessel wall is proportional to the diameter of the muscle x the pressure inside the vessel
(F = D x P). The wall tension require to counteract a given pressure in a spherical
cavity is proportional to the radius of the cavity.
5.0.PRINCIPAL MECHANISMS OF CARDIOVASCULAR DISEASE
Many diseases can involve the heart and blood vessels but generally cardiovascular
dysfunction results from five main mechanisms: -
1. Failure of the pump

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2. An obstruction to flow
3. Regurgitation flow
4. Disorders of cardiac conduction
5. Disruption of the continuity of the circulatory system
6.0.INVESTIGATIONS IN CARDIOVASCULAR DISEASE
1) IMAGING
a) Chest X-Ray
 Is taken in postero-anterior (PA) direction at maximum inspiration.
 The heart is close to the X-ray film to minimize magnification of the chest with
respect to the thorax.
 Lateral view chest X-ray may give more information when PA is abnormal.
 Look at the heart size, calcification and lung fields
Interpretation

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Heart Size
i) The cardio-thoracic Ratio (CTR)
 The maximum transverse diameter of the heart is compared with the maximum
 Transverse diameter of the chest measured from the inside of the ribs.
 Is usually less than 0.5 (50%) except in:-
1) Neonates
2) Infants
3) Athletes
4) Patients with skeletal deformities (Scoliosis, funnel chest)
 A transverse cardiac diameter of more than 15.5 cm is abnormal.
 Pericardial effusion or cardiac dilation increases the ratio.
ii) Patterns of specific chamber enlargement seen on the chest X-ray
a. Left Atrial dilatation
 Prominence of the left atrial appendage on the left heart boarder.
 A double atrial shadow to the right of the sternum.
b. Left ventricular enlargement
 Increased CTR
 Smooth elongation and increased convexity of the heart border.
c. Right Atrial enlargement
 Right boarder of the heart projects into right lower lung field.
d. Right ventricular enlargement
 Increased CTR
 Upward displacement of the apex of the heart.
e. Ascending aortic dilatation/enlargement
 Prominence of the aortic shadow
f. Dissecting of the ascending aorta
 Widening of the mediastinum
Calcification
 Occurs due to tissue degeneration
 Seen on the lateral or a penetrated PA view but best studied by CT scanning
 Calcification can be seen in:- Pericardial
 Valvular
Lung Fields
 Increased in vascularity an in size of hilar vessels seen when there are left to right
shunts.
 When there is pulmonary ligaemia there is a paucity of vascular markings and a
reduction in diameter of arteries.
 Prominence of pulmonary arteries hili and pruned (reduced in size) at the
peripheral Lung fields as seen in pulmonary arterial hypertension.

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Kerley Lines
 Septal lines seen when the interlobular septa in the pulmonary interstitium become
prominent
 May be because of lymphatic engorgement or oedema of the connective tissues of
the interlobular septa.
 Usually occur when pulmonary capillary wedge pressures reach 20 - 25 mmHg.
 Kerley A lines
o Are 2-6 cm long oblique lines that are < 1 mm thick and course towards the hilar
o Represent thickening of the interlobular septa that contain lymphatic connections
between the perivenous and bronchoarterial lymphatics deep within the lung
parenchyma
o On chest radiographs they are seen to cross normal vascular markings and
extend radially from the hilum to the upper lobes
 Kerley B lines
o These are 1-2 cm thin lines in the peripheries of the lung
o Are perpendicular to, and extend out to the pleural surface
o Represent thickened sub pleural interlobular septa and are usually seen at the
lung bases.
 Kerley C lines
o Short lines which do not reach the pleura (i.e not B or D lines) and do not course
radially away from the hila (i.e not A lines).
 Kerley D lines
o Are exactly the same as Kerley B lines, except that they are seen on lateral chest
radiographs in the retrosternal air gap
Causes
1) Pulmonary Oedema
2) Neoplasm
a. Lymphangitic spread Of Cancer (E.G Lymphangitis Carcinomatosis) : Kerley
Lines With A Fine Peripheral Reticular Pattern e.g. breast, stomach, pancreatic
and lung cancers
b. Lymphoma - pulmonary lymphoma
3) Pneumonia
a. Viral Pneumonia
b. Mycoplasma Pneumonia
c. Pneumocystis Pneumonia
4) Interstitial Pulmonary Fibrosis
5) Pneumoconiosis
6) Sarcoidosis

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Pleural Effusion
 Abnormal pulmonary vasculature
 Fluid level
 Opacity
 Loss of costo-phrenic and cardio-phrenic angles
b) MRI (Magnetic Resonance Imaging)
 Non-invasive imaging technique
 A powerful magnetic field is used
 Cardiac MRI that uses radio waves, magnets, and a computer to create pictures of
the heart. This gives a 3D image of the moving as well as still pictures of the heart.
c) Nuclear Imaging
 Primarily used is Ischaemic Heart Disease
 Myocardial structure & function can be assessed by radio-nucleide imaging
techniques
 Thallium (with behaves as potassium) is taken up by healthy myocardium
 Ischaemia or infarction produces unclear image with a “cold” spot.
d) CT Scanning
 Useful showing the size and shape of the cardiac chambers as well as the thoracic
abdominal aorta and Mediastinum.

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2) ELECTROCARDIOGRAM (EGG)
 Is a recording of the electrical activity of the heart
 Is the only way of diagnosing rhythm and conduction problems
 Is the vector sum of the depolarization and repolarization potential of the myocardial
cells (Summation of action potentials of all myocardial cells)
 The shape of the wave form of the EGG depends on the speed and direction of the
depolarization process through the heart
 Depolarization initiating each heart beat begins at Sino-Atrial node and spreads as
an advancing wave through the atria which are depolarized simultaneously to the A-
V Node
 Depolarization spreads from the atria to ventricles via the Bundle of HIS that begins
at A-V Node passing into the interventricular septum where it divides into right and
left branches
 Left branch divides into 2 smaller branches (fascicles) which supply anterior and
posterior parts of left ventricle respectively
 Bundle branches subdivide into the Purkinje fibres that form a network of cells to
carry the depolarization wave to the myocardial cells
 Return of ventricular muscle cells to their resting electrical state is called
repolarization
EGG Waveform
Terminology
 P wave - 1st deflection corresponds to depolarization and the atria
 QRS Complex - 3 deflections - 1st downwards (Q wave), 2nd upwards (R wave) and
3rd downwards (S wave) corresponds to depolarization of the ventricle.
 T Wave - repolarization of ventricular muscles.
 Upward deflection is a depolarization wave is moving towards recording electrodes

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 Downward deflection repolarization wave is moving away from the recording
electrodes.
Time intervals
 All EGG recorders run a standard paper speed of 25 mm/s.
 EGG paper is standardized so that 5 large squares pass under the recorder stylus
each second.
 One large square is equivalent to 0.2 sec.
 Each large square is subdivided into five small squares each equivalent to 0.04s.
 Heart rate can be calculated from the number of squares between QRS complexes.
 Time taken by each part of the depolarization sequence in each cardiac cycle is
 Calculated by the number of small squares it occupies.
PR interval
 Is the time taken for depolarisation to spread from SAN to Atria to AVN through the
Bundle of HIS bundle to the ventricle
 Shown by number of small squares between beginning of P wave and the beginning
of the ORS complex.
 Normal upper limit 0.20 seconds.
 Width of QRS complex indicates the time taken by the depolarisation wave to spread
throughout the ventricles.
QT intervals
 Time taken for the whole depolarization sequence in ventricles.
 Obtained from the number of squares between beginning of QRS complex and of T
wave.
Abnormalities of Conduction
(a) AV Node/Bundle of HIS
 Prolonged PR interval
1) 1st degree heart block - P Wave is followed by QRS complex.
2) 2nd degree heart block - some P waves are followed by QRS complexes but
others are not. There are 3 varieties of 2nd degree heart block
3) 3rd degree (complex) – no P waves are conducted, ventricular escape rhythm
controls the heart with a slow rate, QRS complexes are wide and abnormal.
(b) His bundle branches
 Right bundle - branch block, broadening of QRS complex
 Left bundle branch block - wide QRS complex, inverted T wave

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3) ECHOCARDIOGRAPHY
- Use echoes of ultrasound waves to map the heart and study its function.
4) PHONOCARDIOGRAPHY
 Application of a sensitive microphone to the chest which allows heart sounds and
murmurs to be recorded.
5) CARDIAC CATHETERIZATION
 Is introduction of a thin radio-opaque tube (catheter) into the circulation
 The pressure in the right heart chambers, left ventricle, Aorta and pulmonary artery
can be measured.
 During the procedure blood samples can be taken to measure the concentration of
Ischaemic metabolites e.g. lactate oxygen content.
 Radio opaque contrast material is injected.
 Quality intra-cardiac shunts
6) URINALYSIS
 Amount
 Haematuria
 Culture
 Microscopy
 Proteins

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7) TOTAL BLOOD COUNT
 Red blood cells
 White blood cells
 Platelets
8) Urea And Electrolytes
9) C-Reactive Proteins
10)Blood sugars
11)Liver Function Tests
12)Blood Cultures
13)Blood Lipid Profiles
 Total cholesterol - below 200 milligrams per deciliter (mg/dL), or 5.2 millimoles
per liter (mmol/L).
 Low-density lipoprotein (LDL) cholesterol - less than 130 mg/dL (3.4 mmol/L),
and under 100 mg/dL (2.6 mmol/L) is even better.
 High-density lipoprotein (HDL) cholesterol - 60 mg/dL (1.6 mmol/L) or higher,
though it's common that HDL cholesterol is higher in women than men.
 Triglycerides - be less than 150 mg/dL (1.7 mmol/L)

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Lesson 2: Congenital Heart Diseases
Learning Outcomes
At the end of the lesson the learner shall be able to: -
1. Describe the pathology of congenital heart disorders
1.0.INTRODUCTION
Congenital heart disease is the abnormality of the heart or blood vessels present from
birth. It is the most important cause of heart disease in the early years of life and the
incidence is higher in premature infants. Cardiac malformations occur during the stage
of cardiac development (3rd - 8th week of gestation). Cardiac abnormalities could be
incompatible with intrauterine life, manifest shortly after birth when foetal circulation
changes to the postnatal circulation, cause cardiac malfunction only in adult life or be
entirely innocent.
Congenital anomalies are morphologic defects that are present at birth. These
anomalies may occur are malformations, disruptions, sequences and syndromes.
 Malformations are primary errors of morphogenesis where there is an intrinsic
abnormal development process. They are as a result of multiple causes.
 Disruptions result from secondary destruction of an organ or body region that was
previously in normal development. Results from extrinsic disturbance in
morphogenesis.
 Deformations result from extrinsic disturbance of morphogenesis through local or
generalized compression of the growing foetus by abnormal biomechanical forces
e.g. uterine constraints such as maternal factors (which ones?) and foetal factors
(such as?).
 Sequence – a pattern of cascade anomalies (examples?)
 Syndrome - collection of congenital anomalies
2.0.DEVELOPMENT OF THE HEART
 The remarkable development of the heart occurs in 6 – 7 days but becomes obvious
at day 18 or 19 in the cardiogenic area of the mesoderm layer where a paired mass
of specialized cells called the heart cords form
 After a short time a hollow centre develops in each cord to form a heart tubes
 The heart tubes begin to migrate towards each other during day 21 and soon fuse to
form a single median endocardial heart tube
 The process of fusion is accompanied by dilatations and constrictions of the tube so
that when fusion is completed during the 4th week five distinct regions can be seen
 These regions are the truncus arteriosus, bulbous cordis, ventricle, atrium and
sinus venosus.
3.0.AETIOLOGY
1. Idiopathic/unknown (90%)
2. Genetic – arise from karyotypic aberrations, gene mutations and multifactorial
inheritance. Examples - chromosomal abnormalities e.g. Trisomy 21 (Down’s
syndrome)

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3. Environmental factors such as infections in the mother during pregnancy e.g.
rubella, drugs and alcohol and cigarette smoking, radiation, maternal diabetes
4. Multifactorial causes
4.0.PATHOGENESIS
The timing of prenatal teratogenic determines the occurrence and type of anomaly
produced. The embryogenic period which takes first 9 weeks (early - 1st 3 weeks) and
foetal period (10 weeks to birth) determine the outcomes as organogenesis occurs
mainly during embryogenic whereas during the foetal period there is growth and
development of organs with reduced susceptibility to teratogenic agents but
susceptible to growth retardation.
5.0.CLINICAL EFFECTS/FEATURES
Children with significant congenital anomalies have disturbance in the haemodynamics
of blood flow, failure to thrive, cyanosis, increased risk to recurrent or chronic
infections and high risk of infective endocarditis.
6.0.CLASSIFICATION
1. Malposition of the heart
2. Shunts (Cyanotic Congenital Heart Disease) - Left-to-right shunts and Right-to-left
shunts
3. Obstructions (Obstructive Congenital Heart Disease)
7.0.MALPOSITIONS
1. Ectopia Cordis
 This is a birth defect in which the abnormally located outside the thoracic cavity and
has defective heart muscles and coverings
Diagram 2.1: Ectopia Cordis
 Most commonly the heart protrudes outside the chest through a split sternum and
less often the heart may be situated in the abdominal cavity or neck
 Condition is fatal in first days of life. It is associated with other malformations such as
Tetralogy of Fallot, pulmonary atresia, atrial and ventricular septal defects, and
double outlet right ventricle. Other non-cardiac malformations may be present such
as cleft palates

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 Most cases result in stillbirth or death shortly after birth. Depending on the position
of the heart from birth ectopia cordis can be classified into four categories namely -
cervical, thoracic, thoracoabdominal and abdominal.
2. Malposition (Dextrocardia)
Dextrocardia is the presence of the heart ion the right hemithorax with the apex of the
heart points to the right side of the chest. It is usually associated with major anomalies of
the heart e.g. transposition of the atria or great arteries.
Diagram 2.2: Dextrocardia
8.0SHUNTS (CYANOTIC CONGENITAL HEART DISEASES)
8.1 Introduction
A shunt is an abnormal communication between heart chambers, between blood
vessels or between the heart chambers and blood vessels. The pressure differences in
heart chambers determines the direction of shunting of the blood - left-to-right shunting
(more common) or right-to-left shunting.
8.2 Classification
1. Left-to-right shunts (late cyanosis or acyanotic heart diseases)
a. Atrial Septal Defect (ASD)
b. Ventricular Septal Defect (VSD)
c. Patent Ductus Arteriosus (PDA)
d. Atrioventricular Septal Defect (AVSD)
2. Right-to-left shunts (early cyanosis or cyanotic heart diseases ) – 5TS
a. Tetralogy of Fallot (TOF)
b. Transposition of great arteries
c. Truncus arteriosus and stenosis
d. Tricuspid atresia and stenosis
e. Total anomaly of pulmonary venous drainage/connection

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8.3 LEFT-TO-RIGHT SHUNTS (Acyanotic Heart Disease)
These cause cyanosis several months or years after birth.
1. Atrial Septal Defect (ASD)
 ASD is an abnormal opening in the atrial septum that allows free communication
between the left and right atria
 Accounts for 10% of congenital heart diseases
 Usually asymptomatic until in adulthood when pulmonary hypertension (in 10%
cases) is induced causing late cyanotic heart disease and right-sided heart failure
 Effects are produced due to left-to-right shunt at the atrial level with increased
pulmonary flow
 Result in hypertrophy of the right atrium and ventricle, enlargement and
haemodynamic changes in tricuspid and pulmonary valves, reduction in size of left
atrium and left ventricle and reduction in size of the mitral and aortic orifices.
Diagram 2.3: ASD
Features
1. Right ventricular hypertrophy
2. Cardiac failure
3. Cyanosis (late)
4. Haemodynamic changes + Murmur
5. Failure to thrive
2. Ventricular Septal Defect (VSD)
 Most common congenital anomaly of the heart in which there is incomplete closure
of the ventricular septum allowing free communication between the left and right
ventricles
 Usually recognized early in life
 30% cases occur in isolation but it is frequently associated with other structural
anomalies especially the Tetralogy of Fallot
 Explain the pathophysiology of these
features.
 How will use elicit them on physical
examination

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 50% of the smaller defects of less than 0.5 cm in diameter close spontaneously
 Clinical features range from asymptomatic murmurs to late cyanosis and fulminant
chronic heart failure depending on the size of the defect
 Effects are produced due to left-to-right shunt at the ventricular level, increased
pulmonary flow and increased volume in the left side of the heart
 Result in hypertrophy and dilatation of the right atrium and ventricle, endocardial
hypertrophy of the right ventricle and enlargement and haemodynamic changes in
all the heart valves
Diagram 2.4: VSD
Features
1. Hypertrophy and dilatation of the right atrium
2. Hypertrophy and dilatation of the right ventricle
3. Murmur
4. Cardiac failure
5. Failure to thrive
Diagram 2.5: Effects of VSD
 Explain the pathophysiology of
these features.
 How will use elicit them on
physical examination

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3. Patent/Persistent Ductus Arteriosus (PDA)
The ductus arteriosus (DA) is a normal vascular connection between the aorta and the
bifuractaion of the pulmonary artery which allows communication between the aorta
and the pulmonary artery in the foetus (foetal life). Normally at term the ductus closes
within the first 1-2 days of life as a result of muscular contraction due to the effect of
relatively high oxygen tension and reduced local prostaglandin E (PGE2) synthesis.
Persistence of ductus arteriosus beyond 3 months of life is usually permanent and
abnormal. PDA which accounts for 10% of congenital heart diseases usually occurs as
an isolated anomaly in 85-90% cases. It may be associated with VSD, coarctication of the
aorta and pulmonary or aortic stenosis. There is an accompanying left ventricular
hypertrophy and pulmonary artery dilatation.
The cause for patency of the DA is idiopathic but it is associated with continued
synthesis of PGE2 after birth. This has been established by evidence of association of
respiratory distress syndrome (RDS) with PDA and pharmacologic closure of PDA with
administration of indomethacin to suppress PGE2 synthesis
Diagram 2.6: PDA
Pathophysiology
 PDA allows the shunting of blood from the high pressure aorta to the low pressure
pulmonary artery, increasing the volume of blood passing through the lungs and
returning to the left atrium.
 This is similar to an increased preload and leads to left atrial dilation, increased LA
pressure, increased PV pressure and ultimately pulmonary congestion (left-sided
congestive heart failure).
 Bulging of the aorta and pulmonary artery proximal to the PDA occurs as a result of
increased blood volume and turbulent flow.
 There is always a pressure difference between the aorta and pulmonary artery
(greatest during systole), and consequently continuous flow through the PDA
producing the characteristic continuous murmur.

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 The increased flow through the pulmonary artery can result in pulmonary
hypertension. When the pressure in the pulmonary artery equals or even exceeds
that of the aorta, either the diastolic portion of the murmur or the complete murmur
may disappear due to flow reversal (reverse shunting PDA)
 Blood then bypasses the lungs and the patient presents with cyanosis and a
compensatory polycythaemia.
Effects
1. Loud murmur (machinery murmur)
2. Pulmonary hypertension
3. Right ventricular hypertrophy
4. Right atrial hypertrophy
5. Dilated ascending aorta
Diagram 2.7: Effects of PDA
1.0.RIGHT-TO-LEFT SHUNTS (Cyanotic Congenital Heart Disease)
In right-to-left shunts there is shunting of blood from the right side of the heart to the left
side allowing entry of poorly oxygenated blood into the systemic circulation. This
results in early cyanosis hence the description of congenital cyanotic heart disease.
These shunts (communication channel) can allow movement of emboli from venous
sources to pass directly into the systemic circulation resulting in what we would call
paradoxical emboli.
1. Tetralogy of Fallot (TOF)
TOF accounts for 10% of children born with heart abnormalities. It is composed of four
(tetralogy) cardinal anomalies namely: - 1) VSD (the shunt), 2) displacement of the
aorta to the right side (dextraposition of the aorta) so as it overrides the VSD, 3)
pulmonary stenosis (obstruction) with ventricular outflow obstruction and 4) right
ventricular hypertrophy. Severity of symptoms in TOF is determined by the extent of
right ventricular outflow obstruction and the size of the VSD. A large VSD and a mild
pulmonary stenosis lead to a left-to-right shunt without cyanosis and a severe
pulmonary stenosis results in a cyanotic right-to-left shunt. When there is complete
obstruction survival can only occur through a patent ductus arteriosus (PDA) or dilated
bronchial arteries.
 Why is PDA classified as a left-to-right
shunt disorder?

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Effects
1. Hypertrophy of the right atrium and right ventricle
2. Cyanosis
3. Failure thrive
4. Cardiac failure
5. Murmurs
Diagram 2.8: Tetrology of Fallot (TOF)
1 - Pulmonary stenosis (a form of right ventricular outflow tract obstruction)
2 - Right ventricular hypertrophy
3 - Overriding aorta
4 - Ventricular septal defect
2. Transposition of Great Arteries (TGA)
The aorta arises from the right ventricle while the pulmonary artery emanates from the
left ventricle. TGA is common in children of diabetic mothers. The 2 common types are
regular transposition (commonest) where the aorta is displaced anteriorly and the to
the right of the pulmonary trunk type) and corrected transposition. In majority of the
cases children die within the first few weeks/months if untreated and the prognosis
depends on severity of tissues hypoxia and the ability of the right ventricle to maintain
aortic blood flow.

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Diagram 2.9: Transposition of Great Vessels
3. Truncus Arteriosus
This is a rare abnormality with a poor prognosis associated with numerous connected
defects of the heart. The embryological structure known as the truncus arteriosus
never properly divides into the pulmonary artery and aorta resulting in a single large
common vessel receiving blood from both the left and right ventricle. There is an
associated VSD. The patient presents with early cyanosis due to the right-to-left shunt
but the flow later reverses and the patient develops right ventricular hypertrophy with
pulmonary vascular hypertension.
Diagram 2.10: Truncus Arteriosus

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Clinical Features
 Cyanosis at birth, cardiomegaly and biventricular hypertrophy, heart failure occurs
within weeks, loud second heart sound with a systolic ejection murmur, widen pulse
pressure and bounding arterial pulses
4. Tricuspid Atresia and Stenosis
Is an abnormality often associated with pulmonary stenosis and atresia with an inter-
atrial defect through which right-to-left shunting of blood occurs. There is absence of
tricuspid orifice in tricuspid atresia and a small tricuspid ring with malformed valve
cusps in tricuspid stenosis. Children with tricuspid atresia are cyanotic since birth and
live for a few weeks or months.
Features
 Progressive cyanosis
 Poor feeding
 Tachypnea over the first 2 weeks of life
 Holosystolic murmur due to the VSD
 Left axis deviation on electrocardiography and left ventricular hypertrophy (since it
must pump blood to both the pulmonary and systemic systems)
 Normal heart size
5. Total Anomaly of the Pulmonary Venous Drainage (TAPVD)
TAPVD is a rare cyanotic congenital heart defect (CHD) in which all four pulmonary
veins are malpositioned and make anomalous connections to the systemic venous
circulation. There are no pulmonary veins directly joining the left atrium hence
drainage is into the left innominate vein or to the coronary sinus.
Features
 Volume and pressure hypertrophy of the right atrium and right ventricle, cyanosis,
murmur (systolic ejection) right ventricular heave, RHV, cardiomegaly, cardiac
failure, splitting of S2, S3 gallop, Failure to thrive
2.0.OBSTRUCTIVE CONGENITAL ANOMALIES
They result in obstruction to blood flow from the heart and are classified as obstruction
in the aorta e.g. coarctication of the aorta, obstruction to outflow from the left ventricle –
aortic stenosis and atresia and obstruction to outflow from the right ventricle –
pulmonary stenosis and atresia
1. Coarctication of the Aorta
The aorta is compressed or contracted and 50% cases occur as isolated defects with the
remaining occurring with multiple other anomalies of the heart. There is localized
narrowing of the aorta in any part with the constriction being more often distal to the
ductus arteriosus (post-ductal or adult type) or occasionally proximal to the ductus
arteriosus (pre-ductal or infantile type) on the transverse aorta. Causes of Death:
Chronic cardiac failure, aortic dissection, intracranial haemorrhage and infective
endocarditis

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Diagram 2.11: Coarctication of the Aorta
2. Aortic Stenosis and Atresia
The most common abnormality of the aorta is bicuspid aortic valve, which has less
functional significance but predisposes to calcification. Complete aortic atresia is rare
and incompatible with neonatal survival. Aortic stenosis may be congenital or acquired.
Congenital aortic stenosis is of three types –
(1) Valvular stenosis where there valves cusps are irregularly thickened and
malformed
(2) Subvalvular where there is a thick fibrous ring under the aortic valves causing
subaoratic obstruction and
(3) Supravalvular stenosis that has a fibrous constriction above the sinuses of valsalva.
Effects
1. Left ventricular hypertrophy (pressure overload)
2. Post-stenotic dilatation of the aortic root
3. Infective endocarditis
4. Sudden death (rare)
3. Pulmonary Stenosis and Atresia
This is the commonest form of obstructive congenital heart disease where there is fusion
of the cusps of the pulmonary valve forming a diaphragm like obstruction to blood flow
and it may also occur as a component of TOF or may occur in conjunction with
transposition abnormalities. In pulmonary stenosis there is no communication between
right ventricle and the lungs so blood bypasses the right ventricle through an inter-
atrial septal defect and enters the lungs via the PDA. WHAT ARE THE FEATURES?

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Lesson 3: Cardiac Failure (Heart Failure)
Learning Outcomes
At the end of the lesson the learner should be able to: -
1. Define cardiac failure
2. Describe the causes of cardiac failure
3. Describe the pathology of cardiac failure with respect to each cause
1.0.DEFINITION
 Cardiac failure is a situation when the ventricular myocardium fails to maintain a
circulation adequate for body requirements despite adequate venous return
 The heart is unable to deliver a supply of oxygenated blood that is adequate for
meeting metabolic needs of peripheral tissues both at rest and during exercise
 Physiologically heart failure is a state in which an increase in filling pressure and
therefore fibre length causes a fall rather than a rise in cardiac output.
 Heart failure (HF) is a syndrome of ventricular dysfunction
Heart failure is a clinical syndrome in which patients have the
 Symptoms typical of heart failure (breathlessness at rest or on exercise, fatigue,
tiredness, ankle swelling)
 Signs typical of heart failure (tachycardia, tachypnoea, pulmonary rales, pleural
effusion, raised jugular venous pressure, peripheral oedema, hepatomegaly)
 Objective evidence of a structural or functional abnormality of the heart at rest
(cardiomegaly, third heart sound, cardiac murmurs, abnormality on the
echocardiogram, raised natriuretic peptide concentration)
2.0.RISK FACTORS
Age, Hypertension, Physical inactivity, Diabetes, Obesity, Smoking, Gender , Nutrition ,
Family history of heart failure, Enlargement of the left ventricle, Some types of valvular
heart disease, including, infection, Coronary artery disease, High cholesterol and
triglycerides, Excessive alcohol consumption, Prior heart attack, Certain exposures,
such as to radiation and some, Types of chemotherapy, Infection of the heart muscle
(usually viral)
3.0.CAUSES OF CARDIAC FAILURE
The causes of cardiac failure include: -
1) Intrinsic pump failure
2) Increased work load on the heart - Pressure overload and Volume overload
3) Impaired filling of the cardiac chambers
4) Multifactorial ( a combination of the above factors)
3.1. Pump Failure
Intrinsic pump failure is the most common and important cause of heart failure. The
heart has 2 main pumps: - the left pump which pumps blood to the peripheral organs
and the right one that pumps blood to the lungs. Pump failure frequently results from
weakness of ventricular contractions.

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Causes of Intrinsic Pump Failure
1. Myocardial weakness
2. Cardiac rhythm disorders
3. Reduced or poor myocardial response
4. Multifactorial (multiple causes)
Myocardial Weakness
A situation where muscle weakness leads to unsatisfactory pumping action of the heart
muscles due to reduced contractibility of myocardium leading to secondary reduction
of Blood supply.
Causes
The causes of myocardial weakness can classified based on aetiology or function.
a) Aetiological Classification
1. Myocardial Ischaemia and infarction
2. Infections
3. Nutritional Deficiency states- Beri Beri (Thiamine)
4. Systemic connective Tissue Disorders - rheumatoid arthritis, systemic lupus
erthromatosus (S.L.E) and polyarteritis Nodosa.
5. Cardiomyopathies - reduces the contractibility of the myocardium
6. Metabolic/Endocrine - diabetes mellitus, altered Thyroid function
[Hyperthyroidism/Hypothyroidism], adrenal cortical insufficiency and acromegaly.
7. Storage disorders - Glycogen storage disease
8. Infiltrations – Amyloidosis, Sarcoidosis, Heamochromatosis
9. Sensitivity and Toxic reactions - drugs e.g. cytotoxic drugs, alcohol, cobalt and
barbiturates
10.Physical agents - Irradiation
b) Functional Classification
This is based on whether the chambers are dilated or not. Dilatation can be generalized
or focal. Myocardial weakness may be due to hypertrophic and/or restrictive
cardiomyopathy
Pathology of Myocardial Weakness
1. Expulsion of blood by the ventricles during systole is reduced due to the weak
pumping action of the ventricles leaving a residual blood volume.
2. During diastole the chambers dilate to contain both residual and incoming blood
causing dilatation of the ventricles putting the ventricles at a greater disadvantage
as more force will be required to pump out the increased volume of blood (Frank-
Starling Law). But due to the weakness of the myocardium, this is will not achieved
and therefore blood pools in the ventricles.
3. If the destruction is not halted, dilatation of the ventricles and failure are
progressive.
4. Ventricular dilation (left ventricle and right ventricle) leads to the stretching of the
respective valves (mitral and tricuspid) resulting in valve incompetence of the Mitral
and Tricuspid valves respectively.

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5. This worsens the situation due to reduced cardiac output and damming of blood in
veins which increase systemic venous pressure (systemic venous pressure) slowing
the general circulation.
CARDIAC RHYTHM DISORDERS
Effective pumping action of the heart is achieved by alternate relaxation and
contraction allowing blood to enter the chambers (during relaxation – diastole) and
force in out during contraction (systole). This is achieved by the co-ordination,
conduction and rhythmicity of the cardiac muscle together with the efficiency of the
conducting system of the heart, which comprises of the sino atrial Node (SAN), atrial
Ventricular Node (AVN), the Purkinje tissue and the Bundle of His.
Circus Movement
The cardiac impulse conduction around the heart without stopping hence there is
continuous impulse conduction due to an enlarged heart (long pathway), slow
conduction e.g. failure of the purkinje tissue, decreased refractory period which results
from epinephrine, sympathetic stimulation and irritation of the heart by disease and
transmission of impulses in figures of 8’s for example in ventricular fibrillation
Rhythm Disorders
Arrhythmias can be can disorders of impulse conduction at sites such as the SAN, AVN,
atria, Ventricles and Purkinje tissues or disorders of impulse formation in the form of
abnormal site of origin or abnormal rate of impulse discharge.
Tachycardia
This is a rhythm rate greater than 100 beats per minute. Causes of tachycardia include:
exercise, anxiety and any disorder that increases the sympathetic nervous system
stimulation
Pathology
Tachycardia impairs diastolic refilling of ventricles and shortens the coronary artery
diastolic filling reducing blood supply to the heart. This results in decreased stroke
volume and cardiac output thus decreasing blood supply to the myocardium resulting
in ischaemia [Myocardial], which reduces the performance of the heart. Examples of
Tachycardia are: - atrial fibrillation, atrial flutter, paroxysmal Tachycardia and
atrial tachycardia
Atrial fibrillation
Atrial fibrillation is an impulse transmission of 350 – 600 beats per minute. The impulse
is irregular in time and force. It is worse on exercise.
Pathology
Fewer impulses reach the ventricles to effect contraction and therefore the stroke
volume and cardiac output reduce hence compromising blood supply and there is
irregular ventricular response to transmission of impulses from the atria. The resulting
incompetent emptying of the ventricles causes pooling of blood in the heart chambers

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leading to dilatation and hypertrophy of the ventricles and cardiac failure if the situation
is not reversed
Causes
Rheumatic Heart Disease (RHD), coronary Heart disease, hypertensive heart disease.
Thyrotoxicosis, cardiomyopathies (Dilated and hypertrophic cardiomyopathy),
constrictive pericarditis, pulmonary embolism and alcohol abuse
Atrial Flutter
Atrial flutter is an impulse frequency of 125– 300 beats per minute. It is usually regular
but can become irregular if there is fluctuating heart block.
Pathology
Fewer impulses reach the ventricles to effect contraction and therefore the stroke
volume and cardiac output are reduced hence compromising blood supply. There is
irregular ventricular response and the resulting incompetent emptying of the ventricles
causes pooling of blood in the heart chambers leading to Dilatation and
Causes
Digoxin toxicity, cardiomyopathy, chronic ischaemic heart disease and rheumatic heart
Disease (RHD)
Paroxysmal Tachycardia
Is an impulse transmission of 150 – 250 beats per minute and it is intermittent
Bradycardia
Bradycardia is an impulse rate of below 60 beats per minute
Pathology
In partial heart block at SAN some impulses reach ventricles to effect contraction but
stroke volume cardiac output and heart rate are reduced but in total heart block at SAN
no impulses pass to effect ventricular contraction hence the ventricles contract at 25
beats/min. (Normal for ventricular Tissue). This is inadequate to sustain required blood
supply.
Causes
Physiological (athletes and during sleep) and pathological - cardiac - acute Myocardial
infarction, drugs (Beta blockers, Digoxin) and heart block; non cardiac -
hypothyroidism, obstructive jaundice and increased intracranial pressure
Heart Block
Interferes with the conduction process and impulses are blocked from getting through
the ventricular myocardium resulting in ventricles contracting at a much slower rate
than normal. This can occur at the SAN, AV – Block; 1st degree there is delayed impulse
transmission from to ventricles; 2nd degree there is intermittent failure of impulse

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transmission (Mobitz I block, Mobitz II block and 2:1 or 3:1 (advanced) block and 3rd
degree where there is complete A–V block
Causes
Myocardial infarction, digoxin toxicity, idiopathic fibrosis, congenital heart disease,
aortic valve disease, infiltration - tumours, syphilis, endocarditis, inflammation -
rheumatoid arthritis, ankylosing spondylitis, Reiter’s syndrome and sarcoidosis,
rheumatic fever and diphtheria
3.2. Increased Workload on the Heart
Pressure Overload
This is a situation where there is increased resistance to the expulsion of blood from
the ventricles or inflow of blood into ventricles.
Causes
1. Left Ventricle - aortic stenosis and systemic hypertension
2. Right ventricles - pulmonary hypertension, mitral stenosis and lung Disease
Pathology
This can be considered in two groups of ventricular outflow obstruction and ventricular
inflow obstruction.
Ventricular Outflow Obstruction
This can be as a result of hypertension (pulmonary and systemic hypertension), aortic
stenosis and pulmonary Stenosis
Pathology
1. Obstruction to out flow of blood from the ventricles causes increased afterload
(ventricular) with the response of ventricular hypertrophy but the ventricular
capacity remains (Starling’s Law)
2. Increased in ventricular muscle bulk causes muscles stiff and this will require higher
atrial pressure for refilling and so there occurs Atrial hypertrophy
3. With the increased load due to increased afterload the ventricles dilate needing
high wall tension to maintain the systolic pressure (Laplace’s Law)
4. Coronary vessels are unable to supply the increased muscle bulk with adequate
blood so the muscle fibres become ischaemic and die off. The ischaemic muscle
tissue is replaced by fibrous tissue, which has poor contractibility.
Ventricular Inflow Obstruction
Causes
This can result from mitral stenosis, tricuspid stenosis, cardiac tumours, external
Pressure or Constriction e.g. constrictive pericarditis and endomyocardial fibrosis
Pathology
1. Obstruction of in flow of blood from the atria causes increased afterload (atrial) with
the response of atrial hypertrophy but the atrial capacity remains (Starling’s Law)

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2. Increase in atrial muscle bulk makes them stiff and this will require higher systemic
venous pressure for refilling and emptying and so there occurs atrial hypertrophy
3. With increased load (due to increased afterload) the atrial dilatation requires high
wall tension to maintain the systolic pressure (Laplace’s Law) hence there occurs
pooling of blood in the systemic and pulmonary vessels. This reduced ventricular
filing
4. Reduced ventricular filling cardiac output is reduced
5. Coronary vessels are unable to supply the increased muscle bulk with adequate
blood so the muscle fibres become ischaemic and die off. The ischaemic muscle
tissue is replaced by fibrous tissue, which has poor contractibility
6. The increased atrial action causes hypertrophy and dilatation, which result in Atrial
fibrillation
Volume Overload
This occurs when the ventricles are required to expel more than the normal amount of
blood
Causes
1. Incompetent valves that allow blood to flow back into the chambers increasing the
blood volume e.g. aortic regurgitation and pulmonary regurgitation.
2. States with high general circulation (High Output States) such as severe anaemia,
thyrotoxicosis, Beriberi and patent Ductus Arterious (PDA).
3. Hypoxia resulting from lung disease (increase circulation) e.g. cor pulmonalae
which leads to an increase in circulation.
4. Arterio-venous shunts between the left and right sides of the circulation causing
cyanosis and hence hypoxia which causes increased circulation
Explanation/Pathology
The pathology is based on the effects of ventricular hypertrophy and dilatation, Frank-
Starling’s Law and Laplace’s Law
3.3. Impaired Filling of the Cardiac Chambers
The cardiac output is decreased and cardiac failure ensues due to extra cardiac causes
or defects in the filling of the heart chambers as seen in cardiac tamponade and
constrictive pericarditis
3.4. Multiple Factors
This involves a combination of the above-mentioned factors.
4.0.COMPENSATORY MECHANISMS
The functioning of the heart is guided by intimate integrating four principle
determinants that regulate the stroke volume and cardiac output. There are two
intrinsic factors - preload (ventricular end-diastolic volume) and afterload
(intraventricular systolic tension during ejection) and two extrinsic autonomic
modulations - contractility (variable force of ventricular contraction independent of
loading) and heart rate (frequency of contraction).

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The Basic Adaptive Mechanisms
 The cardiovascular system maintains arterial pressure and perfusion of vital organs
when there is huge haemodynamic burden or disturbance in myocardial
contractility through a number of adaptive mechanisms geared to sustaining
adequate cardiac performance.
 These adaptive mechanisms include
o Frank-Starling mechanism
o Myocardial structural changes (dilatation and hypertrophy)
o Activation of neuro-hormonal systems (adrenaline, RAA and ANP).
Frank-Starling Principle
 Describes the relationship between preload and cardiac performance
 Sates that, normally, systolic contractile performance (represented by stroke volume
or CO) is proportional to preload within the normal physiologic range
Normally (top curve), as preload increases, cardiac performance also increases.
However at a certain point, performance plateaus, then declines. In heart failure (HF)
due to systolic dysfunction (bottom curve), the overall curve shifts downward, reflecting
reduced cardiac performance at a given preload, and, as preload increases, there is
less of an increase in cardiac performance. With treatment (middle curve), performance
is improved, although not normalized.
Compensatory Enlargement of the Heart
Compensatory enlargement of the heart prevents heart failure or postpones heart
failure. This is achieved through three processes namely: - hypertrophy (results from
increased demand for pumping) dilatation (accommodation of excessive blood) and
remodelling (change in structure of myocytes)
Classification
The compensatory changes in heart failure can be classified as: -
Local
1. Chamber enlargement
2. Myocardial hypertrophy
3. Increased heart rate

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Systemic Changes
1. Activation of the sympathetic nervous system and RAAS
2. Release of ANP and ADH
5.0.PATHOPHYSIOLOGY OF CARDIAC FAILURE
Systolic dysfunction
 HF with reduced EF (ejection fraction)
 The ventricle contracts poorly and empties inadequately, leading initially to
increased diastolic volume and pressure and decreased ejection fraction
Diastolic dysfunction
 In diastolic dysfunction (also called HF with preserved EF)
 Ventricular filling is impaired, resulting in reduced ventricular end-diastolic volume,
increased end-diastolic pressure, or both
 Contractility and hence EF remain normal; EF may even increase as the poorly filled
LV empties more completely to maintain CO
 Markedly reduced LV filling can cause low CO and systemic symptoms.
Cardiac response
 If ventricular function is impaired, a higher preload is required to maintain CO
 Ventricles are remodelled over time
 LV becomes less ovoid and more spherical, dilates, and hypertrophies while the RV
dilates and may hypertrophy
 Initially compensatory, these changes eventually increase diastolic stiffness and wall
tension (ie, diastolic dysfunction develops), compromising cardiac performance,
especially during physical stress. Increased wall stress raises O2 demand and
accelerates apoptosis (programmed cell death) of myocardial cells
 Dilation of the ventricles can also cause mitral or tricuspid valve regurgitation with
further increases in end-diastolic volumes.
Haemodynamic responses:
 With reduced CO, O2 delivery to the tissues is maintained by increasing O2
extraction and sometimes shifting the oxyhemoglobin dissociation curve to the right
to favour O2 release.
 Reduced CO with lower systemic BP activates arterial baroreflexes, increasing
sympathetic tone and decreasing parasympathetic tone. As a result, heart rate and
myocardial contractility increase, arterioles in selected vascular beds constrict,
venoconstriction occurs, and Na and water are retained
 These changes compensate for reduced ventricular performance and help maintain
hemodynamic homeostasis in the early stages of HF
 However, these compensatory changes increase cardiac work, preload, and
afterload; reduce coronary and renal perfusion; cause fluid accumulation resulting in
congestion; increase K excretion; and may cause myocyte necrosis and arrhythmias.
Renal responses:
 Decreased perfusion of the kidneys (and possibly decreased arterial systolic stretch
secondary to declining ventricular function) activates the renin-angiotensin-
aldosterone system
 The renin-angiotensin-aldosterone-vasopressin (antidiuretic hormone [ADH])
system causes a cascade of potentially deleterious long-term effects

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 Angiotensin II worsens HF by causing vasoconstriction, including efferent renal
vasoconstriction, and by increasing aldosterone production, which enhances Na
reabsorption in the distal nephron and causes myocardial and vascular collagen
deposition and fibrosis
 Angiotensin II increases norepinephrine release, stimulates release of vasopressin,
and triggers apoptosis
 Angiotensin II may be involved in vascular and myocardial hypertrophy, thus
contributing to the remodelling of the heart and peripheral vasculature, potentially
worsening HF. Aldosterone can be synthesized in the heart and vasculature
independently of angiotensin II (perhaps mediated by corticotropin, nitric oxide,
free radicals, and other stimuli) and may have deleterious effects in these organs.
Neurohumoral responses
 Help increase heart function and maintain BP and organ perfusion, but chronic
activation of these responses is detrimental to the normal balance between
myocardial-stimulating and vasoconstricting hormones and between myocardial-
relaxing and vasodilating hormones.
6.0.MANIFESTATIONS OF CARDIAC FAILURE
Manifestations of cardiac failure depend on the rate of development of the casual
factors and the side of the heart affected. Development of causal factors can results in
acute or chronic cardiac failure. The side of the heart involved that is left side (Left
ventricular failure - LVF), right side (Right Ventricular Failure - RVF) and total heart
failure (congestive cardiac failure) when both sides of the heart are [Congestive cardiac
failure - CCF (LVF + RVF)]
Grading Of Cardiac Failure - New York Heart association (NYHA) Classification
Grade I No limitation of physical activity. Ordinary physical activity does not cause undue
fatigue, palpitation, or dyspnoea.
Grade II Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity
results in fatigue, palpitation, or dyspnoea.
Grade III Marked limitation of physical activity. Comfortable at rest, but less than ordinary
activity results in fatigue, palpitation, or dyspnoea.
Grade IV Unable to carry on any physical activity without discomfort. Symptoms at rest. If any
physical activity is undertaken, discomfort is increased.

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6.1. ACUTE CARDIAC FAILURE
Causal factors develop rapidly or suddenly as in myocardial infarction (massive),
gross pulmonary embolism, cardiac arrhythmias, acute bacterial toxaemia, rheumatic
fever and rapture of Ventricles and valve cusps. In severe cases of acute cardiac failure
(due to myocardial infarction) there is marked reduction in cardiac output with selective
peripheral vasoconstriction following sympathetic activity causes CARDIOGENIC
SHOCK with central venous pressure increased (different for Hypovolaemic shock and
hence the different principles of management). There is decreased cardiac output that
leads to cerebral hypoxia
6.2. CHRONIC HEART FAILURE
The causal factors develop gradually (slowly) as in myocardial ischaemia due to
artheroma, severe systemic hypertension, chronic valvular disease/lesions and chronic
lung disease causing hypoxia leading to Pulmonary Hypertension. In this regard
cardiac output is diminished and tissue hypoxia results.
Dominant clinical
feature
Symptoms Signs
Peripheral
oedema/congestion
Breathlessness;
Tiredness, fatigue;
Anorexia
Peripheral oedema; Raised jugular
venous pressure; Pulmonary oedema;
Hepatomegaly, ascites; Fluid overload
(congestion); Cachexia
Pulmonary oedema Severe
breathlessness at rest
Crackles or rales over lungs, effusion;
Tachycardia, tachypnoea
Cardiogenic shock
(low output
syndromes)
Confusion; Weakness
Cold periphery
Poor peripheral perfusion; SBP ,90
mmHg; Anuria or oliguria
High blood pressure
(hypertensive heart
failure)
Breathlessness Usually raised BP, LV hypertrophy, and
preserved EF
Right heart failure Breathlessness
Fatigue
Evidence of RV dysfunction, Raised
JVP, peripheral oedema,
hepatomegaly, gut congestion
6.3. LEFT SIDED HEART FAILURE (LEFT VENTRICULAR FAILURE, LVF)
Introduction
The left ventricle is more commonly affected than the right ventricle. Left ventricular
failure leads to right ventricular failure then total heart failure (CCF).
Causes of LVF
1. Ischaemic Heart Disease (IHD) particularly Myocardial Infarction
2. Chronic Hypertension/Hypertension
3. Aortic valvular disease due to rheumatic endocarditis, aortic stenosis (calcific),
syphilitic heart disease and congenital heart disease
4. Mitral incompetence/mitral valve disease
5. High output conditions – severe anaemia, AR, fever, thyrotoxicosis, A-V
malformations, Beri Beri
6. Cardiomyopathy
7. Adhesive mediastino-pericarditis

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Pathology
1. During systole the left ventricle fails to expel all the blood it receives hence contains
an increasing volume of blood at the end of systole
2. During the next diastole there is accumulation of the residual blood (left during
systole) and the incoming blood during diastole. Increased diastolic volume causes
dilatation of the ventricle further increasing inadequacy of contraction.
3. Ventricular dilation causes stretching of valve rings (mitral 10cm) resulting in
incompetence (Mitral Regurgitation - MR)
4. Mitral regurgitation allows some blood expelled during systole passes through the
valve to the left atria increasing pressure here (left atria) causing venous congestion
in the pulmonary system causing oedema of the lungs (pulmonary oedema)
5. Pulmonary congestion leads to shortness of breath, orthopnoea, PND and
haemoptysis.
6. This retrograde loss of blood through the leaking valve further compromises the
ventricular output and cardiac output.
7. Decreased output causes renal ischaemia (acute tubular necrosis, oliguria), CNS
ischaemia -anoxic neuronal changes (dizziness, confusion), bowel ischaemia –
mucosal or transmural necrosis (GI bleeing, sepsis) and skeletal ischaemia
(weakness, fatigue, reduced exercise tolerance)
8. With the situation persisting there is ventricular dilatation and hypertrophy.
Clinical Features (Manifestation)
The clinical manifestations result from insufficient blood flow through the various body
organs and tissues plus the pulmonary congestion due to stasis of blood in the
pulmonary circulation. The clinical manifestations include or involve the heart (size,
abnormal heart sounds, pulse), the lungs (dyspnoea, orthopnoea, paroxysmal nocturnal
dysnpoea (PND), cough, and cyanosis), pedal oedema, kidneys, brain and the liver
1) The Heart
a) Size – cardiomegaly
b) Abnormal heart sounds
c) The Pulse rate – there can be tachycardia or bradycardia
d) Pulse rhythm and pulse character

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Cardiomegaly
 Increase in the heart side due to dilatation and hypertrophy of the heart chambers.
 Assessment of cardiomegaly is based on subjective visual impression, physical
examination (palpation of the apex beat), determination of the cardio-thoracic ratio
and volume measurement (length x width x depth x 0.63)
Abnormal Heart Sounds
There may be a third or fourth heart sound. The third Heart sound (S3 Gallop) occurs
due to rapid ventricular filling. This can be due to young age (normal), constrictive
pericarditis, rheumatic mitral stenosis, severe non-rheumatic mitral regurgitation and
valvular heart disease – mitral/Aortic regurgitation. The fourth heart sound (S4
Gallop) occurs in situations of increased atrial activity due to left ventricular disease,
left ventricular hypertrophy, dilated heart cavity, pulmonary stenosis, pulmonary
hypertension and acute myocardial infarction
2) The Pulse
 Pulsus paradoxicus (Kussmal’s sign) or Pulsus alternans
3) The Lungs
The effects seen in the lungs are dyspnoea, cyanosis, cough and crepitations.
Congestion and oedema occur in the pulmonary venous circulation and the alveolar
capillaries as the fluid collects in alveoli (pulmonary) and in severe cases rhexis of red
blood cells into the capillaries occurs causing haemorrhage into alveolar spaces.
Dyspnoea occurs due to inadequate oxygenation of blood flowing though functionally
impaired lungs, anoxaemia of respiratory centre and the carotid sinus and decreased
vital capacity of lungs due to vascular distension
PND (Paroxysmal Nocturnal Dyspnoea)
 Pulmonary congestion and oedema are worsened by severe functional imbalance of
ventricles
 Paroxysmal (nocturnal) dyspnea is a sudden-onset of severe shortness of breath and
coughing, awakening the patient.
 Factors that produce paroxysmal dyspnoea include:
1. Depression of respiratory centre during sleep (decreases arterial oxygen)
2. Decreased ventricular function due to decreased sympathetic tone (decrease
myocardial contractility and hence cardiac output) and
3. Redistribution of fluid to the chest.
Pathophysiology of PND
1. Excessive sympathetic activity causes venoconstriction so blood moves from the
systemic veins to the pulmonary circulation.
2. During sleep, irritability of CNS decreases hence accumulation of oedema with
provoking defence system e.g. cough
3. Decreased muscular activity allows pooling of blood in veins and change in position
or movement expels blood causing sudden increase volume in the lungs.
 Explain the pathophysiology of orthopnoea. How will you determine orthopnoea

35. UNIT 1: CARDIOVASCULAR PATHOLOGY
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4. Reabsorption of interstitial fluid in recumbence causing increase blood volume.
5. In active state, hydrostatic pressure at the capillary level is high leading to fluid
effusion into the interstitial spaces. At night (inactive) the reverse happens leading to
net fluid flow in the vascular system, heart and pulmonary circulation leading to
congestion causing paroxysmal dyspnoea
6. The patient lying down improves the venous return from the limbs worsening the
situation.
Cough occurs as a result of irritation of mucosa (oedema fluid). The cough may be
productive of blood-streaked, frothy sputum due to pulmonary congestion and oedema
Pulmonary oedema occurs due to venous congestion in the lungs and causes wheezy
respirations “Cardiac asthma” Rhonchi, basal crepitations and Chyne-strokes
respiration in chronic pulmonary oedema. Cyanosis may be present or not.
4) Kidneys
Reduced cardiac output causes low glomerular filtration rate (GFR) reducing the renal
blood flow, which results in renal anoxia and vasoconstriction reflexes. There is sodium
retention leading to oedema formation.
5) Brain
Reduced cardiac output compromises blood flow to the brain resulting in cerebral
anoxia, irritability, and loss of attention span, restlessness, stupor and coma.
6) Liver
Increased systemic venous pressure causes hepatic congestion (Tender hepatomegaly)
with minor abnormalities such increased SGOT, SGPT, serum Bilirubin and
abnormalities in BSP excretion
6.4. RIGHT VENTRICULAR FAILURE (RVF)
Introduction
RVF usually combined with LVF and pure RVF occurs in few instances. RVF is usually
caused by left ventricular failure (LVF). When caused by pulmonary diseases it is
described as the heart of pulmonary disease (cor pulmonale).
Causes
1. Myocardial Infarction (not severe than the left ventricle)
2. Chronic Destructive Pulmonary Disease - chronic Bronchitis, emphysema,
pulmonary fibrosis, pulmonary abscess and pulmonary tuberculosis (PTB).
3. Massive pulmonary embolism
4. Pulmonary hypertension following LVF secondary to IHD
5. Viral myocarditis
6. Constrictive pericarditis
7. Valvular lesions (Tricuspid stenosis and congenital pulmonary stenosis)
8. Left sided failure
9. Congenital heart disease

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Pathology
1. Left ventricular failure causes increase left atrial pressure and the pressure in the
pulmonary arterial pressure which increases the workload on the right ventricle
leading to right ventricular hypertrophy and eventually failure.
2. The failing right ventricle is unable to expel all the blood received hence becomes
dilated.
3. The dilatation results in the stretching of the Tricuspid valve ring leading to
Tricuspid regurgitation (incompetence) and blood accumulates in the right atrium,
systemic and portal venous systems leading to systemic venous congestion and
causing “Cardiac” type of oedema.
4. There is increased diastolic volume which causes visceral congestion and effusions,
peripheral congestion and oedema (stasis, pitting oedema and distended neck
veins).
Manifestations (Features)
Primary physiologic disturbance involves damming of blood in the spleenic, systems
and portal system and inadequate flow from lungs to left ventricle. Venous congestion
and Stagnation occurs throughout the body causing renal anoxia, which results in
Sodium and water retention hence increasing the blood volume.
The Heart - As LVF
Liver
Congested and enlarged (hepatomegally). In severe cases there is central
haemorrhagic necrosis of liver and healing occurs by formation of a Fibrous tissue a
situation that causes “Cardiac Cirrhosis”
Raised JVP and Oedema
There is congestion of the peripheral venous system resulting in raised jugular venous
pressure and pitting pedal oedema.
Kidneys
Congestion and Renal anoxia causes disturbed renal function
Pedal oedema
Brain - As in LVF
Portal system
Spleen – may become congested and enlarged
Therefore is a systemic venous congestion syndrome
Radiographic signs of RV failure:
 Increased VPW1 due to dilatation of the superior vena cava
 Dilatation of azygos vein
 Dilatation of the right atrium
 In many cases there will be both signs of RV and LV failure
1 vascular pedicle width

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Sonographic signs of RV failure:
 Dilatation of the inferior vena cava (IVC) and hepatic veins
 Hepatomegaly
 Ascites
6.5. CONGESTIVE (TOTAL) HEART FAILURE (CCF)
It involves failure of both Right and Left Ventricles which may fail spontaneously for
example in severe myocardial infarction, severe toxic myocarditis e.g. Diphtheria, Beri
beri and congestive cardiomyopathy
Causes
1. Increased workload for both ventricles e.g. RHD with lesions involving mitral and
Aortic valves
2. Increased Cardiac Output e.g. in severe anaemia and thyrotoxicosis (In high output
failure - the fall in cardiac output is relative from a previously high cardiac output).
But may still be low output failure with an abnormally low output
3. Ventricular stiffness that follows poor response to SAN and hypertrophic
cardiomyopathy
NB: Thromboembolic phenomenon is common in CCF due to blood stagnation. This
increases the risk of pulmonary embolism
Low Output Failure – Causes
1. Myocardial disease
2. Ischaemic heart disease (IHD)
3. Myocarditis
4. Cardiomyopathy
5. Arrthymias
6. Hypertension
7. Valve stenosis
8. Cor pulmonalae
Cardinal Signs of CCF
The cardinal signs of CCF include: -
1. Pedal oedema
2. Raised JVP
3. Tender Hepatomegally
4. Cardiomegally
5. Gallop rhythm
6. Basal crepitations
 Explain the pathophysiology of
these signs
 Describe how you can elicit these
features on physical examination
 What are the differentials of these
signs?
 Explain the evolution of congestive
cardiac failure and its effects based
on the concepts of forward and
backward failure

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7.0.STAGES OF CARDIAC FAILURE
8.0.CAUSES OF CARDIAC ENLARGEMENT
Enlargement of the heart occurs due to increased workload (volume and pressure).
1. Left Ventricular Hypertrophy (LVH)
Common causes of marked left ventricular hypertrophy include: -
1. Systemic Hypertension
2. Aortic stenosis and regurgitation or mitral regurgitation
3. Mitral insufficiency
4. Coartication of the Aorta
5. Collusive coronary artery disease
6. Congenital abnormalities e.g. septal defects - PDA
7. High Cardiac output states- thyrotoxicosis, severe anaemia and A – V fistula
Mild left ventricular hypertrophy is caused by hypertrophic cardiomyopathies and left
ventricular failure of any cause
2. Right Ventricular Hypertrophy (RVH)
1. Left ventricular hypertrophy (LVH)
2. Chronic Lung disease – e.g. chronic emphysema, bronchioectasis, pneumoconiosis,
pulmonary vascular disease
3. Pulmonary stenosis and insufficiency
4. MitraI regurgitation (MR), Mitral Stenosis (MS)
5. Congenital heart disease (C.H.D) with shunts
6. Pulmonary stenosis (PS)
7. LVH/LVF

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3. Compensatory Dilatation
Follows valve incompetence or shuts and is usually accompanied by hypertrophy of the
respective ventricles.
Causes
1. Valvular insufficiency – mitral and/or aortic regurgitation in Left ventricular
dilatation and tricuspid and/or pulmonary regurgitation in right ventricular
dilatation.
2. Left-to-right shunts e.g. VSD
3. Conditions with high output states – give examples
4. Myocardial diseases e.g. cardiomyopathy (which type?)
5. Systemic hypertension
9.0.DIAGNOSIS
Framingham Criteria
 Simultaneous presence of at least 2 major criteria
 Simultaneous presence of at least 1 major + 2 minor criteria
 Major criteria
o PND; Neck vein congestion; Rales; Radiographic cardiomegaly; Acute pulmonary
oedema; S3 gallop; Increased CVP > 16 cm at right atrium; Hepatojugular reflux;
> 4.5 kg weight loss in 5 days of diuresis
 Minor criteria
o Bilateral ankle oedema; Nocturnal cough; Dyspnoea on ordinary exertion;
Hepatomegaly; Pleural effusion; Reduced vital capacity; Tachycardia > 120 bpm
Framingham Criteria for Congestive Heart Failure
Activity Major Minor
History Paroxysmal nocturnal dyspnea X
Orthopnea X
Dyspnea on exertion X
Nocturnal cough X
Weight loss in response to treatment X
Physical
examination
Neck vein distention X
Rales X
S3 gallop X
Hepatojugular reflux X
Hepatomegaly X
Bilateral ankle oedema X
Tachycardia X
Chest radiograph X
Cardiomegaly X
Pulmonary oedema X
Pleural effusion X
Pulmonary
function
testing
Vital capacity decreased one third from
maximum
X

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10.0. LUNG-HEART INTERACTIONS
The normal pulmonary circulation is high capacitance, low resistance and the right
ventricle is thin. LVF causes pulmonary congestion which decreases PO2 resulting in
impaired left ventricular function. Chronic LVF causes chronic pulmonary congestion
and vascular changes (pulmonary hypertension) which results in right ventricular
hypertrophy (also occur in VSD).
Right ventricular hypertrophy or pulmonary disease lead to high pulmonary vascular
resistance (PVR) resulting in high pulmonary artery and high right ventricular
pressures, which affect left ventricular function. Congenital heart disease e.g. VSD
causes a left-right shunt which leads to increased right ventricular pressure.
11.0. COMPLICATIONS
1) Renal failure
2) CVA (stroke)
3) Valvular heart disease
4) Hepatic failure
5) Cardiac arrhythmias
6) Anaemia
7) Venous stasis
8) DVT
9) Pulmonary embolism
10)Cardiac arrest
Explain the pathophysiology of these
complications

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Lesson 4: Ischaemic Heart Disease (IHD)
Learning Outcomes
At the end of the lesson the learner should be able to: -
1. Define ischaemic heart disease
2. Describe blood supply to the heart
3. Evaluate risk factors in and causes of IHD
4. Describe the pathophysiology and pathology of IHD
5. Discuss the clinical features and complications of IHD
1.0.INTRODUCTION
Ischaemic heart disease is a situation when there is diminished myocardial blood
supply due to arterial blood flow obstruction or vasoconstriction. It is an acute or
chronic state of cardiac disability arising from an imbalance between the supply of
oxygen and myocardial demand for these nutrients. Obstruction or narrowing of the
coronary arterial system is the most common cause of myocardial anoxia hence the
term coronary artery disease is used synonymously with IHD.
2.0.BLOOD SUPPLY TO THE MYOCARDIUM
Diagram 4.1: Blood supply to the Myocardium (Anterior)
Coronary Circulation
 There are two coronary (the left and right coronary artery) arteries responsible for
blood supply to the myocardium
 The dominant artery is the one that gives off the AV nodal artery and supplies the
posterior descending artery. In 95% of males and 85% of females, the right
coronary artery is dominant while in the remaining 5% and 15% respectively, the

42. UNIT 1: CARDIOVASCULAR PATHOLOGY
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circumflex artery is dominant. Some individuals have collateral channels that
connect the major coronary arteries.
 The coronary arteries are good examples of end arteries but there exists a
collateral cardiac and extra-cardiac collateral circulation with a rich
anastomososes even though the blood vessels involved are usually very small and
can only open if occlusion of the coronary arteries is gradual
 There is a rich anastomosis of very small vessels between the right and left coronary
arteries in the myocardium. The extra-cardiac anastomosis occurs through the
pericardium from four pulmonary branches, two caval branches that anastomose
with the branches of internal thoracic, bronchial and phrenic arteries.
Venous Drainage
Coronary veins run parallel to major coronary arteries draining blood into the coronary
sinus, which empties blood directly into the right atrium.
3.0.RISK FACTORS
1. Fixed factors e.g. age, male sex and positive family history
2. Potentially changeable with treatment
a. Strong Association - hyperlipidaemia, cigarette smoking, hypertension and
diabetes mellitus
b. Weak Association – personality, obesity and physical inactivity, gout,
contraceptive pill and heavy alcohol consumption
4.0.AETIOPATHOGENESIS
.
IHD is mainly caused by disease affecting coronary arteries which is majorly due to
atherosclerosis (90% cases). The aetiology of IHD falls under three broad headings of
coronary atherosclerosis, superadded changes in coronary atherosclerosis and non-
atherosclerotic causes.
Diagram 4.2: Effects of Coronary Artery Disease
5.0.CAUSES OF IHD
1. Reduced coronary blood flow due to obstruction
a. Atheroma/artherosclerosis (depends on the distribution, location and fixation of
the atherosclerotic plaques)
b. Arteritis e.g. inflammation
c. Thrombosis – e.g. hypercoagubility states
d. Vascular spasms
e. Embolus
Coronary Artery Disease
Angina Pectoris
Asymptomatic state
Myocardial
Infarction
Chronic Ischaemic Heart
disease
Sudden Death

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f. Coronary ostial stenosis (e.g. syphilis)
g. Coronary arteritis (e.g. polyarteritis)
h. Aneurysm – coronary artery
i. Trauma - contusion
j. Compression - tumours
2. Decrease in the flow of oxygenated blood
a. Anaemia
b. Carbohyhaemaoglobinaemia
c. Hypotension – coronary perfusion pressure
3. Increased demand for oxygen
a. Increased cardiac output - thyrotoxicosis
b. Myocardial hypertrophy - aortic Stenosis, hypertension
6.0.PRESENTATION
The presentation depends on the characteristics of the lesion in the coronary arteries in
terms of onset, duration, degree, location and extent. This influences the effects of
myocardial ischaemia which may present as: -
1. Asymptomatic state
2. Angina pectoris
3. Myocardial infarctions (acute and chronic)
4. Cardiac arrhythmias
5. Cardiac Failure
6. Sudden death
ANGINA PECTORIS
1.0 INTRODUCTION
 Angina pectoris is a clinical syndrome associated with transient sudden, severe
paroxysmal substernal pain due to diminished blood flow through the coronary artery
(inadequate perfusion). Angina means strangling. The pain is prompted by exertion,
cold and emotional stress and lasts a short time. The pain radiates to the shoulder
(jar, check, left arm) and is usually relieved by rest and drugs (vasodilatation -TNT)
 Angina occurs because myocardial cells become ischaemic but the damage is
reversible. Reduced blood supply can be as a result of stable or unstable plaques in
the vessels. Stable plaques narrow coronary arteries so that blood flow is insufficient
for even a moderate increase in cardiac work (e.g. climbing stairs) and the patient
complains of chest pain (angina) which is relieved on rest.
 Unstable plaques only produce clinical problems when an acute event occurs
causing the fibrous cap of the plaque splits and blood from the lumen can reach the
soft necrotic centre. Rupture of the plaque causes distortion and enlargement of the
plaque as well as releasing the plaque contents which activate the thrombotic
cascade. Platelets and fibrin aggregate blocking the lumen and the platelet
constituents (TXA2, histamine and serotonin) promote vasospasm which worsens the
situation.

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2.0 CAUSES
1. Coronary artery disease resulting in impaired perfusion – atheroma, syphilis, valve
disorders (AS, AR, severe MS) and vasospasm
2. Myocardial infarction - promotes Angina by decreasing blood supply to the
surviving myocardium around the infarction. It also relieves angina by eliminating
the dead tissue
3.0 PREDISPOSING FACTORS
The predisposing factors include those that result in increased myocardial oxygen
demand such as: -
1. Increased ventricular preload e.g. exercise, anaemia and thyrotoxicosis
2. Increased ventricular afterload e.g. hypertension, valvular lesions – AS and
obstructive cardiomyopathy.
3. Increased ventricular wall tension due to dilation and hypertrophy
4. Decreased heart function e.g. myocarditis and tachycardia
Factors Prompting Attacks
The factors prompting attacks include physical activity, exposure to cold, exercises,
injury, shock and coronary artery spasm
Risks
The main risk factors are myocardial infarction, cardiac failure and sudden death
(ventricular filtration)
Pathology
a. Coronary artery shows arteriosclerosis, patchy fibrous intimal thickening,
calcification, accumulation of lipid debris and fibrosis
b. Myocardium exhibits ischaemic changes and fibrosis
c. ECG shows abnormal conduct
Classification
1. Class 0: Asymptomatic
2. Class 1: Angina with strenuous Exercise
3. Class 2: Angina with moderate exertion
4. Class 3: Angina with mild exertion
1. Walking 1-2 level blocks at normal pace
2. Climbing 1 flight of stairs at normal pace
5. Class 4: Angina at any level of physical exertion
4.0 PRESENTATION and CLINICAL PATTERNS OF ANGINA
There are 3 overlapping clinical patterns of angina pectoris namely stable (typical)
angina, Prinzmetal’s variant angina and unstable (crescendo) angina.
Stable (Typical) Angina
Most common pattern (also described as classical or exertional) characterized by
attacks of pain following emotional or physical exertion due to chronic stenosing

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coronary atherosclerosis and relieved by rest. This is because the coronary artery
cannot perfuse the myocardium adequately when the workload on the heart increases.
The ECG shows depression of the ST segment due to poor perfusion of the
subendocardial region of the left ventricle. There is no elevation of enzymes in blood
because there is no irreversible myocardial injury.
Prinzmetal’s variant Angina
Variant (Prinzmetal’s) angina is characterized by pain which occurs at rest with no
relationship with physical activity. This is mainly due to sudden vasospasm of the
coronary trunk induced by coronary atherosclerosis or release of humoral
vasoconstrictors by mast cells in the coronary adventitia. The ECG shows ST segment
elevation due transmural ischaemia. The patients respond well to vasodilators.
Unstable (Decrescendo) Angina
This is also called pre-infarction angina or acute coronary insufficiency due to multiple
factors. It is the most serious variety characterized by more frequent onset of pain,
prolonged duration pain, often occurring at rest. Indicates impending myocardial
infarction and has multiple aetiology.
5.0 INVESTIGATIONS
1) ECG
2) Coronary angiography
3) Chest X-Ray
4) VDRL
5) Haemogram + ESR
6) Echocardiography
MYOCARDIAL INFARCTION
1.0 INTRODUCTION
MI is a lethal disease of modern times which occurs as a result of reduced blood supply
(ischaemia) and affects mainly the ventricular myocardium. The cardiac muscle cells
die because of lack of nutrients primarily oxygen resulting from poor blood flow to the
myocardium because of narrowing or total occlusion of one or more coronary arteries.
The magnitude of infarction depends on amount of collateral flow, metabolic
requirements of the cells and duration of ischaemia. Atheroma of the coronary
vessels accounts for the majority of cases but rarer causes include vascular spasm,
emboli, arteritis and anaemia.
2.0 INCIDENCE
 Higher in industrialized countries due to association with atherosclerosis
 Affects more males than females
3.0 CAUSES
– See the causes of ischaemic heart disease
 Why are these investigations above necessary?
 What parameters will you look for when the results are out?
 What are the important findings on examination of cardiovascular
system of a 50 year old man who presents with angina pectorisanaemia aggravates angina
depressed ST levels in stable angina, raise ST levels in prinzmetal's angina
site and severity of luminal narrowing

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4.0 PATTERNS AND TYPES OF INFARCTS
 Classified according to the anatomic regions of the left ventricle involved (anterior,
posterior or inferior, lateral, septal and circumferential; combinations –
anterolateral, posterolateral and anteroseptal) or degree of thickness of the
ventricular wall involved (full thickness or transmural, subendocardial) or laminar or
age (newly-formed or acute/recent/fresh; advanced – old/healed/organized)
 Three main patterns namely regional infarct, transmural infarct and
subendocardial infarct
Regional myocardial infarcts (RMI)
 Accounts for 90% cases. It results from occlusion of a single vessel
 Occupies the segment of myocardium that is normally supplied by a particular
coronary artery
 May involve a variable thickness of the myocardial wall
 Important arteries supplying which whose occlusion result in regional infracts of the
heart are: -
1) Left anterior artery which supplies the anterior wall, lateral wall of the left
ventricle, part of inter-ventricular septum and the apex
2) Left circumflex artery that supplies the posterior wall of the left ventricle.
3) Right coronary artery supplying the right ventricle
4) The left circumflex and right coronary supplying the posterior part of intra-
ventricular septum.
Transmural Infarct
 Results from occlusion of a single coronary vessel and involves full thickness of the
myocardial wall
 Majority result from thrombosis complicating atheroma.
Diagram 4.3: Blood Vessel Blockage Sites

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Subendocardial Infarcts
 Affect the inner wall of left ventricle and account for 10% cases of myocardial
infarcts
 Result from generalized widespread atherosclerosis in all coronary vessels but with
no specific occlusion
 Subendocardial region is most vulnerable part of the myocardium because 1) any
collateral supply that is developed tends to supply the subendocardial part of the
myocardium and 2) the subendocardium is under the greatest tension from the
compressive forces of the myocardium.
 May be confined to the inner half of the myocardium and may be regional or
circumferential.
5.0 CLINICAL PRESENTATION
 May present as acute or chromic myocardial infarction
 Acute myocardial infarction is the most important consequence of coronary artery
disease and many patients die within the first few hours of the onset and the
remaining ones suffer impaired cardiac function.
Diagnosis
Diagnosis of AMI is based on three types of features – clinical features, ECG changes
and serum enzymes determinants.
Clinical Features
 Chest pain(what characteristics?), indigestion, apprehension, oliguria, low grade
fever, shock and acute pulmonary oedema
ECG Changes
 ST segment elevation
 T wave inversion
 Wide deep Q waves
Serum cardiac Markers
 Certain proteins and enzymes are released into blood from the necrotic heart
muscle after myocardial infarction
6.0 PATHOLOGY
 Structural changes
 Microscopy
 Microscopy
Structural Changes
The infarcts have variation in size > 2 cm affecting the inner part of myocardium.
Majority of the infarcts are transmural (whole thickness of myocardium). The right
coronary artery blockage leads to formation of a posterior, inferior infarct affecting the
apex down to the inferior wall of the left ventricle, the adjacent inter-ventricular septum
and the adjacent inferior wall of the right ventricle. 15% of the cases involve the left
circumflex artery affecting the lateral margins of the left ventricle.

48. UNIT 1: CARDIOVASCULAR PATHOLOGY
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Macroscopy
1. Congestion (Blotchy congestion)
2. Pale myocardium
3. Haemorrhagic margins
4. Softened patch (dead tissue)
5. Colour change from grey brown to yellow green
6. Red zone of vascular granulation (later)
Diagram 4.4: Myocardial Infarction
Microscopy
1. Coagulative necrosis changes
2. Polymorphonuclearr leucoytes (neutrophils, monocytes)
3. Digestion of tissues by macrophages
4. Show necrotic changes at the margins
7.0 DIFFERENTIAL DIAGNOSIS
1. Aortic dissection
2. Pulmonary embolism
3. Spontaneous pneumothorax
4. Pericarditis
5. Oesophageal rupture
6. Peptic Ulcer disease
7. Pancreatitis
What are the differentiating features of
these conditions?
What investigations will be crucial in
differentiating these diagnoses

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8.0 COMPLICATIONS
 Explain how these complications occur? Pathophysiology
 How will they present?
 How will you investigate for these complications?

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Lesson 5: Valvular Heart Disease (VHD)
Learning Outcomes
At the end of the lesson the learner should be able to: -
1. Outline the anatomy of the heart valves
2. Describe the causes and mechanisms of valvular damage
3. Explain the pathology and clinical presentation of valvular heart disease
4. Investigations in valvular heart disease
5. Evaluate complications of valvular heart disease
1.0 INTRODUCTION
Valvular heart diseases comprise of the disorders of the heart valves. Normal function of
the heart depends on the mechanical efficiency of the valves whose malfunction
contributes immensely to the disability of heart function.
2.0 VALVE DEFORMITY
A valve deformity can be a stenosis or regurgitation. : Stenosis - a reduction in the
valve aperture and increases pressure load in the preceding chambers. Any time there
is an obstruction to blood flow across the heart three adjustments may occur: - pressure
proximal to the obstruction increases in an attempt to maintain same quality of flow;
amount of flow reduces and hence require less pressure difference across the
obstruction and duration of flow past the obstruction may be prolonged Regurgitation
– incompetence of valves that result in failure of the valve to close completely and
increases volume load on both sides of the valve
Diagram 5.1: Valve Deformities
3.0 CAUSES OF DEFORMITY/DISORDERS
1. Congenital – usually associated with other congenital disorders
2. Acquired - E.g. Rheumatic fever (the commonest cause)
a. Post-inflammatory scarring
b. Degenerative changes with aging
c. Dilatation of the valve ring e.g. in ventricular dilatation

51. UNIT 1: CARDIOVASCULAR PATHOLOGY
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d. Degeneration of collagen support tissue of the valve
e. Acute destruction by acute necrotizing inflammation
The Mitral Valve
1.0 INTRODUCTION
Normal function of the mitral valve depends on the mechanical efficiency of the cusp,
chordae, papillary muscle, pliability and size of fibrous ring or annules and adequacy of
left ventricular contraction. Normal size of circumference is 5 – 12 cm. The valve
consists of 2 leaflets (cusps) - a larger anterior leaflet and a small posterior leaflet,
annules, the chordae tendineae and papillary muscles
Diagram 5.2: Mitral Valve
2.0 PHYSIOLOGY
 Has a cross-sectional area of 5 cm2 and allows ventricular filling at peak rate of 500 –
1000 mls/s
Mitral Stenosis (MS)
Rheumatic Heart disease resulting from acute rheumatic fever is a major cause of mitral
stenosis affecting more female than males. In 2/3 cases the aortic valve is also affected
1.0 AETIOLOGY
a. Congenital
b. Acquired - rheumatic fever /rheumatic heart disease/ (commonest), calcification,
infective endocarditis, rheumatoid arthritis and Systemic Lupus Erythromatosus
(S.L.E.)
2.0 PATHOPHYSIOLOGY
 Disturbance in left ventricular filling due to reduced mitral valve area (1 - 2.5 cm2),
which causes a reduction in peak left ventricular filling rate and loss of normal
period of diastasis.
 During exercise as heart rate increases a pressure gradient develops with an
increase in mean left atrial pressure in an effort to improve ventricular filling. This
will result in left atrial hypertrophy and dilatation.

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 There is chronic left atrial hypertension that causes elevation of pulmonary capillary,
venous and arterial pressures favouring transudation of fluid resulting in oedema
(pulmonary oedema) formation.
 Pulmonary hypertension leads to right ventricular hypertrophy, dilatation and
failure.
 There will also be congestion in systemic veins (raised JVP, hepatomegally and
pedal oedema).
 There is reduced cardiac output due to poor left ventricular filling and right
ventricular failure eventually ending up in cardiac failure.
3.0 PATHOLOGY
There is distortion of normal mitral valve anatomy with fusion of commisures.
1. The cusps:
a) Are thickened, distorted and vascularized throughout (normally they are
vascularized at the base only)
b) Consists of dense fibrous tissue with infiltrations of lymphocytes and plasma cells
c) They are fused along the free margins forming a “Button Hole” or “Fish mouth”
opening
d) There is thrombus formation and calcification
e) Great thickening and rigidity causes stenosis and regurgitation
2. Chordae - shows thickening, fusion and contraction
3. The valve ring is calcified
4.0 CLINICAL FEATURES
Symptoms
The symptoms include - reduction in exercise tolerance, breathlessness, fatigue,
heaviness of limb, palpitations, cough (productive of blood-tinged, frothy sputum and at
times frank haemoptysis), Haemoptysis (due to chest infection, pulmonary infarction,
acute pulmonary oedema and rupture of small blood vessels in lungs. Massive or
recurrent haemoptysis may be the presenting or only symptom of mitral stenosis.),
angina (due to pulmonary hypertension, right ventricular failure and previous coronary
embolism), nocturnal dyspnoea (late complain), recurrent chest infection associated
with cough, purulent sputum and fluid retention (pulmonary oedema), fluid retention
such as pedal oedema, ascites, pleural effusion and pulmonary oedema and features of
embolic phenomenon where any organ could be affected.
Physical Examination (Signs)
General Examination
On general examination there is weight loss, peripheral cyanosis, “Malar flash”, the
pulse is irregular (Atrial fibrillation), rapid with a normal character (but amplitude may
be reduced) or slow rising (small volume, slow rising) and raised JVP if there is right
ventricular failure

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The Pericardium
There is a “tapping apex” due to a palpable first heart sound with a left parasternal
heave due to right ventricular hypertrophy. Loud Hs (first heart sound) with a rumbling
mid-diastolic murmur/thrill.
Effects (Other features)
1. Left atrial myocardial hypertrophy is limited causing increase in pressure in LA and
accumulation of blood in LA and pulmonary veins leading to pulmonary venous
congestion. There is also dilatation of the left atrium
2. Increased pulmonary venous pressure (PVP) causes pulmonary arterial
hypertension leading to right ventricular hypertrophy (RVH) exhibiting features
such as dyspnoea, persistent cough, pulmonary oedema, paroxysmal nocturnal
dyspnoea (PND) and haemoptysis due to engorged blood vessels
3. Right ventricular hypertrophy results in tricuspid regurgitation
4. Congestive cardiac failure
5. Thrombosis
6. Systemic Embolism (worst being cerebral infarction)
7. Atrial fibrillation
8. Pulmonary hypertension results in pulmonary valve regurgitation that produces an
early diastolic murmur (Graham-Steell murmur)
5.0 EFFECTS
1. Left atrial dilatation and hypertrophy
2. Left ventricular hypertrophy and dilatation
3. Diastolic murmur
6.0 INVESTIGATIONS
1. Chest X-ray
a. Heart size is normal or increased (commonly left atrial enlargement)
b. Calcification may be visible
c. The Lung fields show dilated veins with an increase in size of main pulmonary
artery (pulmonary hypertension)
d. Evidence of pulmonary oedema - lymphatic lines, generalized hazy shadowing
and obvious interstitial oedema
e. Pulmonary haemosiderosis in long standing cases
2. E.C.G. shows atrial fibrillation and left atrial hypertrophy (bifid “p” wave)
3. Echocardiogram
4. Cardiac catheterisation.
5. Full haemogram and ESR
7.0 COMPLICATIONS
1. Atrial fibrillation
2. Systemic embolism
3. Pulmonary hypertension
4. Pulmonary infarction
5. Chest infection
6. Infective endocarditis
7. Tricuspid regurgitation

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Mitral Regurgitation (MR)
1.0 AETIOLOGY
Rheumatic heart disease (accounts for 50%) and prolapsing mitral valve are the most
common causes of mitral regurgitation. Any disorder that causes dilatation of the left
ventricle causes mild mitral regurgitation.
Table 5.1: Causes of MR
Structure Anatomical Pathogenesis
Affected Fault
1. Valve cusps Congenital cleft Atrial Septal Defects (ASD)
Redundant cusps - Marfan’s syndrome,
- Floppy valve syndrome, loss of collagen
Perforation - Infective endocarditis
Distortion/Scarring - Rheumatic fever
Iatrogenic - Floppy Valve
2. Chordae Redundant chordae - Marfan’s syndrome, Floppy valve
Ruptured chordae - Floppy valve, Marfan’s syndrome
- Infective endocarditis/Rheumatic
Chordal shortening - Rheumatic, endomyocardial, fibrosis
3. Papillary muscle Dysfunction - IHD and cardiomyopathy
Prolapsing mitral valve ring - Various
Rupture - Acute myocardial infarction
4. Valve ring Dilatation - severe LV disease
Calcification - Various
2.0 PATHOPHYSIOLOGY
 In pure mitral stenosis, there is a large increase in LV output since the pressure in
the left atrium is lower than that in the aorta and resistance to left ventricular ejection
is reduced so the stroke volume increases up to three fold. Ejection of blood begins
almost immediately after start of ventricular contraction and by the time the aorta
valve opens ¼ of the stroke volume has already entered the left atria.
 Incompetence of the mitral valve allows regurgitation of blood into the left atrium
during systole producing LA dilatation.
 During diastole the additional blood volume freely moves into the left ventricle
stretching the left ventricle. This increased volume load leads to LV dilatation and
hypertrophy and eventually left ventricular failure.
 Pressure rise in the left atrium during ventricular systole leads to pulmonary
congestion and oedema.
 There is increased volume in the atria and ventricle leading to dilatation and
hypertrophy of left ventricle.

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3.0 CLINICAL FEATURES
Symptoms - As in mitral stenosis
Signs
On palpation of the praecordium, there is a laterally displaced apex beat (diffuse and
thrusting). Soft 1st heart sound due to incomplete closure of the heart valves with
systolic thrill. A prominent 3rd heart sound resulting from sudden rush of blood into the
dilated left ventricle in early systole. Apical pansystolic murmur (regurgitation occurs
throughout systole) radiating to axilla
Effects
1. Regurgitation of blood into left atrium during ventricular systole
2. Left ventricular Dilatation and Hypertrophy
3. Right ventricular hypertrophy and dilatation
4. Congestion of the lungs and pulmonary hypertension
5. Atrial fibrillation
6. Left ventricular failure leading/right ventricular failure/CCF.
Compensated MR
The volume in left atria increases during ventricular systole but emptied during diastole
with the pressure in the left ventricle remaining about normal (Starling’s Law). In
combined MR/MS there is pulmonary congestion, oedema, hypertension (pulmonary)
and right ventricular hypertrophy.
4.0 INVESTIGATIONS
1. Chest X-ray – shows left atrial and left ventricular enlargement, increased cardio-
thoracic ratio (CTR), valve calcification
2. ECG (bifid p wave)
3. Echocardiogram – dilated left atrium and left ventricle
4. Cardiac catheterisation – prominent left atrial systolic pressure
5. Full Haemogram + ESR.
THE AORTIC VALVE
ANATOMY
The aortic valve consists of 3 semi lunar segments/cusps. The orifice of the aorta
surrounds the cusps. There are 2 posterior cusps (the left and right cusp) and one
anterior cusp. The cusps are larger, thicker and stronger attachments and opposite the
cusps of the aorta there are 3 slight dilatations (Aortic sinuses). Aortic valve disease is a
common cause of sudden cardiac deaths.
Aortic Stenosis (AS)
1.0 INTRODUCTION
Aortic stenosis is an important cause of cardiac disability that represents a fixed
obstruction to the left ventricular ejection at the level of the valve cusps. Aortic stenosis
becomes symptomatic when the valve orifice is reduced to 1 cm2 (normal is 3 cm2).

56. UNIT 1: CARDIOVASCULAR PATHOLOGY
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Diagram 5.3: Aortic Stenosis
2.0 CAUSES
1. Valvular
a. Calcified bicuspid valve
b. Rheumatic(post inflammatory scarring)
c. Senile degeneration (wears & tear) which results from arteriosclerotic
degeneration and calcification
d. Congenital – Valve with a single commissure and Bicuspid valve
e. Infective endocarditis (rare)
f. Hyperlipidaemia (rare)
2. Fixed sub-aortic stenosis (sub-valvular) for example congenital fibrous ridge or
diaphragm.
3. Supravalvular stenosis e.g. congenital fibrous diaphragm above the aortic valve
4. Hypertrophic cardiomyopathy e.g. septal muscle hypertrophy obstructs left
ventricular outflow.
3.0 PATHOPHYSIOLOGY
 Pressure resulting from the aortic stenosis leads to development of a pressure
gradient between the left ventricular cavity and aorta.
 This resistance is fixed hence differs from the increased peripheral resistance of
systemic hypertension which fails during exercise (pressure overload)
 The resultant obstructed left ventricular emptying leads to increased left
ventricular pressure and compensatory left ventricular hypertrophy.
 Left ventricular hypertrophy (LVH) causes an increase in the diastolic stiffness of the
cavity and therefore end-diastolic pressure increase causing pulmonary vascular
congestion.
 The increased ventricular wall thickness (hypertrophy) results in relative ischaemia
of left ventricular myocardium leading to – angina, arrthymias and left ventricular
failure.