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DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
CORONARY
CIRCULATION
OBJECTIVES.
 Coronary blood vessels
 Coronary blood flow: characteristic
features.
 Measurement of coronary blood flow....
CORONARY BLOOD VESSELS
 Coronary arteries –
arise from Root of the
Aorta
 Right coronary artery
– Supplies Rt ventricle,...
CORONARY BLOOD VESSELS
 Left coronary artery –
supplies left ventricle, left
atrium, Ant part of
Interventricular septum ...
CORONARY BLOOD VESSELS
 Major coronary arteries. –
Rt coronary artery travel in
the Epicardium of heart
( superficial ves...
ANASTOMOSIS
 Types.
 Cardiac – Between branches of
two coronary artery & between
branches of 2 coronary arteries
& Deep ...
CORONARY VEINS
 Coronary sinus -- Wide
vein which drain blood
from Myocardium to
Right atrium.
 Tributaries are – Great
...
CORONARY VEINS
 Anterior cardiac vein
– Drains from right
ventricle to right
atrium.
 Thebesian vein –
coronary luminal
...
CORONARY BLOOD FLOW:
CHARACTERISTIC FEATURES
 Normal coronary
blood flow & oxygen
demand.
 A continuous flow of
blood fo...
CORONARY BLOOD FLOW:
CHARACTERISTIC FEATURES
 Normal coronary
blood flow – at rest
250 ml (70ml/100
gm/min)
 5% of cardi...
CORONARY BLOOD FLOW:
CHARACTERISTIC FEATURES
 Oxygen consumption
by the myocardium.
 Very high –
8ml/min/100 gm
tissue
...
PHASIC CHANGES IN
CORONARY BLOOD FLOW
 Blood flow is
determined by
Balance between
Pressure head Aortic
pressure &
Resist...
PHASIC CHANGES IN
CORONARY BLOOD FLOW
 Blood flow to left
ventricles
 During systole – During
contraction myocardium
pro...
PHASIC CHANGES IN
CORONARY BLOOD FLOW
 During Diastole –
 Myocardium relax &
blood flow increases.
 Flow Increases
maxi...
EFFECT OF HEART RATE ON
CORONARY BLOOD SUPPLY.
 During Tachycardia
Duration of diastole
decreases so coronary
blood flow ...
BLOOD FLOW TO RIGHT
VENTRICLE & ATRIA.
 Through coronary
capillaries of right
ventricle shows
similar changes but
to Less...
BLOOD FLOW THROUGH
CORONARY SINUS.
 Inflow Rises from Iso
volumic contraction
phase reaches peak
during Protodiastole
pha...
CLINICAL IMPORTANCE OF
PHASIC CORONARY BLOOD FLOW.
 Sub endocardial
region of left
ventricle
 In Aortic stenosis
 In Co...
SUBENDOCARDIAL REGION OF
LEFT VENTRICLE
 Most Vulnerable to
Ischemia so most
common site of
Myocardial Infarction.
 As t...
COMPENSATORY MECHANISM
 Capillary Density – Much Higher (1100
capillaries /mm2
) than Epicardial region (750
capillaries/...
IN AORTIC STENOSIS
 Pressure in Left
ventricle increases --so
severe compression of
coronary vessels during
systole & Inc...
IN CONGESTIVE HEART
FAILURE.
 Increase in Venous
Pressure --
Decreases aortic
diastolic pressure -- so
effective coronary...
.
MEASUREMENT OF CORONARY
BLOOD FLOW.
 Nitrous oxide method (Kety Method)
 Radionuclides utilization techniques.
 Coron...
NITROUS OXIDE METHOD
(KETY METHOD)
 Principle – based on
Fick’s Principle.
 Procedure – Inhale
mixture of NO & air for 1...
RADIONUCLIDES UTILIZATION
TECHNIQUES.
 Radioactive Tracers
pumped into cardiac
muscle cells by Na-K
ATPase enz & equilibr...
PROCEDURE
 Radionuclide Thallium
-201 injected IV.
 After 10 min amount of
Thallium taken by
myocardial cells
measured b...
CORONARY ANGIOGRAPHIC
TECHNIQUE.
 Combined with 133
Xe
washout using
crystal syntillation
camera tells about
coronary blo...
ELECTROMAGNETIC FLOW
METER TECHNIQUE.
 It tells about Phasic
flow & flow per min.
 Blood flow through left
ventricle det...
REGULATION OF CORONARY
BLOOD FLOW
 LOCAL CONTROL MECHANISM
 Auto regulation
 Role of local metabolite
 Role of endothe...
LOCAL CONTROL MECHANISM
 AUTO REGULATION
 Ability of organ or tissue to
adjust its vascular resistance
& maintain relati...
ROLE OF LOCAL METABOLITE
 At rest 50-70% oxygen
released to
myocardium from
Haemoglobin.
 Almost direct & linear
relatio...
ROLE OF LOCAL METABOLITE
 Role of Adenosine
(Berne Hypothesis) –
increased myocardial
metabolism leads to
degradation of
...
ROLE OF LOCAL METABOLITE
 This crosses Myocardial cell
membrane , ECF, reaches
Precapillary Sphincters of
coronary system...
ROLE OF ENDOTHELIAL CELLS.
 Endothelium releases
vasodilator Autacoids – EDRF,
Prostacyclin, Endothelium
Derived Hyperpol...
NERVOUS CONTROL
MECHANISM
 Direct nervous
control
 Indirect nervous
control
 Neurohumoral
control factors.
Friday, Nove...
DIRECT NERVOUS CONTROL
 Through Sympathetic & Parasympathetic nerve
supply.
 Sympathetic – Innervate Coronary vessels
 ...
INDIRECT NERVOUS CONTROL
THROUGH ACTION ON HEART.
 Sympathetic stimulation – Increases heart rate &
increase force of con...
INDIRECT NERVOUS CONTROL
THROUGH ACTION ON HEART.
 Parasympathetic stimulation. Decreases
coronary blood flow.
Friday, No...
NEUROHUMORAL CONTROL
FACTORS.
 ATP (Purine) – Released with NE causes
Vasoconstriction through P1 & Vasodilatation
throug...
NEUROHUMORAL CONTROL
FACTORS.
 CALCITONIN GENE RELATED PEPTIDE (CGRP) –
with substance P releases EDRF & Produces
maximal...
FACTORS AFFECTING
CORONARY BLOOD FLOW.
 Mean aortic pressure.
 Muscular exercise.
 Emotional excitement.
 Hypotension....
MEAN AORTIC PRESSURE.
 Force for driving
blood into coronary
arteries.
 Directly
proportional.
Friday, November 25, 2016
MUSCULAR EXERCISE.
 At rest – 70ml/100
gm/min
 During exercise –
increases 4 times due
to sympathetic
stimulation by
 I...
EMOTIONAL EXCITEMENT.
 Increase coronary
blood flow due to
increase Sympathetic
discharge
Friday, November 25, 2016
HYPOTENSION.
 Hypotension – reflex increase in NE discharge –
coronary vasodilation – Increase CBF
Friday, November 25, 2...
HORMONES.
 Thyroid Hormone – by increasing metabolism
 Adrenaline & Non adrenaline – by acting on B receptors
 Acetylch...
HEART RATE
 As heart rate increases
– stroke volume
decreases- phasic CBF
& O2 consumption
decreases
 Inverse relationsh...
EFFECT OF IONS
 K ion in low conc – dilate coronary vessels –
Increases CBF
 In Higher conc- constrict coronary vessels-...
METABOLIC FACTORS.
Friday, November 25, 2016
TEMPERATURE.
 Hyperthermia – increase metabolism – increase
adenosine – Increase CBF
 Direct relationship
Friday, Novemb...
CORONARY ARTERY DISEASE.
 Also called Ischemic Heart
disease –
 Causes –
 Atherosclerosis of coronary
arteries.
 Throm...
Thank
You
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CORONARY CIRCULATION

  1. 1. DR NILESH KATE MBBS,MD ASSOCIATE PROF DEPT. OF PHYSIOLOGY CORONARY CIRCULATION
  2. 2. OBJECTIVES.  Coronary blood vessels  Coronary blood flow: characteristic features.  Measurement of coronary blood flow.  Regulation of coronary blood flow  Factors affecting coronary blood flow.  Coronary artery disease. Friday, November 25, 2016
  3. 3. CORONARY BLOOD VESSELS  Coronary arteries – arise from Root of the Aorta  Right coronary artery – Supplies Rt ventricle, Rt atrium, the Posterior part of left ventricle, posterior part of Interventricular septum & SA node Friday, November 25, 2016
  4. 4. CORONARY BLOOD VESSELS  Left coronary artery – supplies left ventricle, left atrium, Ant part of Interventricular septum & left branch of bundle of His.  Predominant supply. – 50% by Right coronary artery, 20% Left coronary artery, 30% Both. Friday, November 25, 2016
  5. 5. CORONARY BLOOD VESSELS  Major coronary arteries. – Rt coronary artery travel in the Epicardium of heart ( superficial vessels) & subdivides into Penetrating branches.  End arteries- appears to be End arteries but shows some Anastomosis. Friday, November 25, 2016
  6. 6. ANASTOMOSIS  Types.  Cardiac – Between branches of two coronary artery & between branches of 2 coronary arteries & Deep Venous System.  Extra cardiac –Between coronary arteries & Vasa vasora of aorta, Vasa vasora of pulmonary arteries, intra thoracic arteries , bronchial arteries & Phrenic arteries. Friday, November 25, 2016
  7. 7. CORONARY VEINS  Coronary sinus -- Wide vein which drain blood from Myocardium to Right atrium.  Tributaries are – Great cardiac veins, Small cardiac vein, Posterior vein of left ventricle & Oblique vein of left ventricle. Friday, November 25, 2016
  8. 8. CORONARY VEINS  Anterior cardiac vein – Drains from right ventricle to right atrium.  Thebesian vein – coronary luminal vessels forms Deep Venous System. Friday, November 25, 2016
  9. 9. CORONARY BLOOD FLOW: CHARACTERISTIC FEATURES  Normal coronary blood flow & oxygen demand.  A continuous flow of blood for supply of oxygen & nutrients Friday, November 25, 2016
  10. 10. CORONARY BLOOD FLOW: CHARACTERISTIC FEATURES  Normal coronary blood flow – at rest 250 ml (70ml/100 gm/min)  5% of cardiac output.  During exercise increases to 3-6 fold.  Blood flow to left is twice Rt ventricle. Friday, November 25, 2016
  11. 11. CORONARY BLOOD FLOW: CHARACTERISTIC FEATURES  Oxygen consumption by the myocardium.  Very high – 8ml/min/100 gm tissue  70-80% of oxygen extracted from each unit as compared to 25% in other tissue. Friday, November 25, 2016
  12. 12. PHASIC CHANGES IN CORONARY BLOOD FLOW  Blood flow is determined by Balance between Pressure head Aortic pressure & Resistance by myocardium. Friday, November 25, 2016
  13. 13. PHASIC CHANGES IN CORONARY BLOOD FLOW  Blood flow to left ventricles  During systole – During contraction myocardium produces Throttling effect on coronary arteries , during Isometric contraction phase blood flow to heart practically Ceases. Friday, November 25, 2016
  14. 14. PHASIC CHANGES IN CORONARY BLOOD FLOW  During Diastole –  Myocardium relax & blood flow increases.  Flow Increases maximally in Isovolumic relaxation phase Friday, November 25, 2016
  15. 15. EFFECT OF HEART RATE ON CORONARY BLOOD SUPPLY.  During Tachycardia Duration of diastole decreases so coronary blood flow reduces but due to Local Metabolite Regulation of blood flow is not seriously affected. Friday, November 25, 2016
  16. 16. BLOOD FLOW TO RIGHT VENTRICLE & ATRIA.  Through coronary capillaries of right ventricle shows similar changes but to Less extent.  Blood flow occurs during Both systole & diastole. Friday, November 25, 2016
  17. 17. BLOOD FLOW THROUGH CORONARY SINUS.  Inflow Rises from Iso volumic contraction phase reaches peak during Protodiastole phase & then gradually Falls. Friday, November 25, 2016
  18. 18. CLINICAL IMPORTANCE OF PHASIC CORONARY BLOOD FLOW.  Sub endocardial region of left ventricle  In Aortic stenosis  In Congestive Heart failure. Friday, November 25, 2016
  19. 19. SUBENDOCARDIAL REGION OF LEFT VENTRICLE  Most Vulnerable to Ischemia so most common site of Myocardial Infarction.  As this part receives almost No blood supply during systole. Friday, November 25, 2016
  20. 20. COMPENSATORY MECHANISM  Capillary Density – Much Higher (1100 capillaries /mm2 ) than Epicardial region (750 capillaries/mm2 )  Minimum diffusion distance – 20% Shorter (16.5 µm) as compared to Epicardial (20.5 µm)  Myoglobin content – Higher than Epicardial region.Friday, November 25, 2016
  21. 21. IN AORTIC STENOSIS  Pressure in Left ventricle increases --so severe compression of coronary vessels during systole & Increase Chance Of MI. Friday, November 25, 2016
  22. 22. IN CONGESTIVE HEART FAILURE.  Increase in Venous Pressure -- Decreases aortic diastolic pressure -- so effective coronary perfusion falls & Coronary Blood Flow Decreases. Friday, November 25, 2016
  23. 23. . MEASUREMENT OF CORONARY BLOOD FLOW.  Nitrous oxide method (Kety Method)  Radionuclides utilization techniques.  Coronary angiographic technique.  Electromagnetic flow meter technique. Friday, November 25, 2016
  24. 24. NITROUS OXIDE METHOD (KETY METHOD)  Principle – based on Fick’s Principle.  Procedure – Inhale mixture of NO & air for 10 min.  During inhalation serial sample of arterial & coronary sinus venous blood taken at fixed intervals  Coronary blood flow  = N2O taken up/min ------------------------------- (A-V) Friday, November 25, 2016
  25. 25. RADIONUCLIDES UTILIZATION TECHNIQUES.  Radioactive Tracers pumped into cardiac muscle cells by Na-K ATPase enz & equilibrate with intracellular K pool.  Distribution of radioactive tracers is Directly proportional to Myocardial blood flow. Friday, November 25, 2016
  26. 26. PROCEDURE  Radionuclide Thallium -201 injected IV.  After 10 min amount of Thallium taken by myocardial cells measured by Gamma- Scintillation camera  Areas of ischemia detected by low uptake. Friday, November 25, 2016
  27. 27. CORONARY ANGIOGRAPHIC TECHNIQUE.  Combined with 133 Xe washout using crystal syntillation camera tells about coronary blood flow. Friday, November 25, 2016
  28. 28. ELECTROMAGNETIC FLOW METER TECHNIQUE.  It tells about Phasic flow & flow per min.  Blood flow through left ventricle determined with the help of Electromagnetic Flow Meter implanted around main left coronary artery. Friday, November 25, 2016
  29. 29. REGULATION OF CORONARY BLOOD FLOW  LOCAL CONTROL MECHANISM  Auto regulation  Role of local metabolite  Role of endothelial cells.  NERVOUS CONTROL MECHANISM  Direct nervous control  Indirect nervous control  Neurohumoral control factors. Friday, November 25, 2016
  30. 30. LOCAL CONTROL MECHANISM  AUTO REGULATION  Ability of organ or tissue to adjust its vascular resistance & maintain relatively constant blood flow over a wide range of blood pressure.  But Fails below 70 mm Hg blood pressure. Friday, November 25, 2016
  31. 31. ROLE OF LOCAL METABOLITE  At rest 50-70% oxygen released to myocardium from Haemoglobin.  Almost direct & linear relationship observed between coronary blood flow & O2 consumption. Friday, November 25, 2016
  32. 32. ROLE OF LOCAL METABOLITE  Role of Adenosine (Berne Hypothesis) – increased myocardial metabolism leads to degradation of Adenine nucleotide to adenosine. Friday, November 25, 2016
  33. 33. ROLE OF LOCAL METABOLITE  This crosses Myocardial cell membrane , ECF, reaches Precapillary Sphincters of coronary system producing strong Vasodilator response.  Role of other metabolite – hydrogen ions, Bradykinins, CO2, PG are other vasodilator substances. Friday, November 25, 2016
  34. 34. ROLE OF ENDOTHELIAL CELLS.  Endothelium releases vasodilator Autacoids – EDRF, Prostacyclin, Endothelium Derived Hyperpolarizing Factors (EDHF)  Also releases Vasoconstrictors Autacoids – Endothelin-1 , Angiotensin II, Endothelium Derived Contracting Factors (EDCF) Friday, November 25, 2016
  35. 35. NERVOUS CONTROL MECHANISM  Direct nervous control  Indirect nervous control  Neurohumoral control factors. Friday, November 25, 2016
  36. 36. DIRECT NERVOUS CONTROL  Through Sympathetic & Parasympathetic nerve supply.  Sympathetic – Innervate Coronary vessels  Transmitters – E & NE  NE – act on α receptors - Vasoconstriction  E – act on β receptors – Vasodilation.  Net result is – Vasoconstriction.  Parasympathetic – Through Vagus very little effect – Vasodilation. Friday, November 25, 2016
  37. 37. INDIRECT NERVOUS CONTROL THROUGH ACTION ON HEART.  Sympathetic stimulation – Increases heart rate & increase force of contraction of heart – increases conversion of ATP to ADP – Coronary Vasodilation – Overrides direct effect of sympathetic Friday, November 25, 2016
  38. 38. INDIRECT NERVOUS CONTROL THROUGH ACTION ON HEART.  Parasympathetic stimulation. Decreases coronary blood flow. Friday, November 25, 2016
  39. 39. NEUROHUMORAL CONTROL FACTORS.  ATP (Purine) – Released with NE causes Vasoconstriction through P1 & Vasodilatation through P2 receptors.  NEUROPEPTIDE Y (NPY) – Released with NE during sympathetic stimulation causes severe Vasoconstriction. Friday, November 25, 2016
  40. 40. NEUROHUMORAL CONTROL FACTORS.  CALCITONIN GENE RELATED PEPTIDE (CGRP) – with substance P releases EDRF & Produces maximal Dilation of Epicardial coronary arteries. Friday, November 25, 2016
  41. 41. FACTORS AFFECTING CORONARY BLOOD FLOW.  Mean aortic pressure.  Muscular exercise.  Emotional excitement.  Hypotension.  Hormones.  Heart rate  Effect of ions  Metabolic factors.  Temperature. Friday, November 25, 2016
  42. 42. MEAN AORTIC PRESSURE.  Force for driving blood into coronary arteries.  Directly proportional. Friday, November 25, 2016
  43. 43. MUSCULAR EXERCISE.  At rest – 70ml/100 gm/min  During exercise – increases 4 times due to sympathetic stimulation by  Increased heart activity  Increase cardiac output  Increase MAP Friday, November 25, 2016
  44. 44. EMOTIONAL EXCITEMENT.  Increase coronary blood flow due to increase Sympathetic discharge Friday, November 25, 2016
  45. 45. HYPOTENSION.  Hypotension – reflex increase in NE discharge – coronary vasodilation – Increase CBF Friday, November 25, 2016
  46. 46. HORMONES.  Thyroid Hormone – by increasing metabolism  Adrenaline & Non adrenaline – by acting on B receptors  Acetylcholine – Increases same as parasympathetic stimulation  Pitressin – Decrease by decreasing coronary resistance  Nicotine – Increases by liberating NE. Friday, November 25, 2016
  47. 47. HEART RATE  As heart rate increases – stroke volume decreases- phasic CBF & O2 consumption decreases  Inverse relationship. Friday, November 25, 2016
  48. 48. EFFECT OF IONS  K ion in low conc – dilate coronary vessels – Increases CBF  In Higher conc- constrict coronary vessels- Decreases -CBF Friday, November 25, 2016
  49. 49. METABOLIC FACTORS. Friday, November 25, 2016
  50. 50. TEMPERATURE.  Hyperthermia – increase metabolism – increase adenosine – Increase CBF  Direct relationship Friday, November 25, 2016
  51. 51. CORONARY ARTERY DISEASE.  Also called Ischemic Heart disease –  Causes –  Atherosclerosis of coronary arteries.  Thrombus formation.  Embolus  Spasm of coronary vessels  Atheromatous coronary vessels stenosis. Friday, November 25, 2016
  52. 52. Thank You
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