NURSING MANAGEMENT
DYSRHYTHMIAS
Chapter 36
This chapter describes basic principles of electrocardiographic
monitoring and recognition and treatment of common
dysrhythmias.
In addition, it presents ECG changes that are associated
with acute coronary syndrome (ACS).
OBJECTIVES
1. Examine the nursing management of patients requiring continuous
electrocardiographic (ECG) monitoring.
2. Differentiate the clinical characteristics and ECG patterns of normal
sinus rhythm, common dysrhythmias, and acute coronary syndrome
(ACS).
3. Compare the nursing and collaborative management of patients with
common dysrhythmias and ECG changes associated with ACS.
4. Differentiate between defibrillation and cardioversion, including
indications for use and physiologic effects.
5. Describe the management of patients with pacemakers and
implantable cardioverter-defibrillators.
6. Select appropriate interventions for patients undergoing
electrophysiologic testing and radiofrequency catheter ablation
therapy
KeyTerms
asystole, p. 795
atrial fibrillation, p. 796
atrial flutter, p. 795
automatic external defibrillator (AED), p. 802
cardiac pacemaker, p. 803
complete heart block, p. 798
dysrhythmias, p. 787
premature atrial contraction (PAC), p. 794
premature ventricular contraction (PVC), p. 799
telemetry monitoring, p. 790
ventricular fibrillation (VF), p. 800
ventricular tachycardia (VT),
atrial systole
bundle of His
Cardiac cycle
ELECTROCARDIOGRAM
The electrocardiogram (ECG) is a graphic tracing of
the electrical impulses produced in the heart.
The electrical activity of the heart is seen either with
an ECG that shows the activity for that moment when
the ECG is obtained or with continuous cardiac
monitoring.
Electrodes placed on the patient’s skin allow various
views of the heart’s electrical activity to be seen.
Each view of the heart is referred to as a lead.
A 12-lead ECG provides 12 different views of the
heart’s electrical activity, 9
Electrocardiogram Graph Paper
ECG paper consists of large (heavy lines) and small (light
lines) squares.
Each large square consists of 25 smaller squares (five
horizontal and five vertical).
Horizontally, each small square (1 mm) represents 0.04
second.
This means that one large square equals 0.20 second and
that 300 large squares equal 1 minute.
Vertically, each small square (1 mm) represents 0.1 millivolt
(mV). This means that one large square equals 0.5 mV.
10
INTERPRETATION OF CARDIAC
RHYTHMS
Step 2. Heart Rate
1. Count the number of small (0.04-second) squares
between two R waves and divide that number into 1500.
This gives the beats per minute, because 1500 small
squares equals 1 minute
This method is used only for regular rhythms and is very
accurate.
2. Six-second method: the 6-second method is used for
irregular rhythms. Count the number of R waves in a 6-
second strip and multiply the total by 10.
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15
INTERPRETATION OF CARDIAC
RHYTHMS
Step 3. PWaves
The P waves on the ECG tracing are
examined to see if (1) there is one P
wave in front of every QRS,
(2) the P waves are regularly
occurring, and (3) the P waves all
look alike
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17
INTERPRETATION OF CARDIAC
RHYTHMS
Step 4. PR Interval
All PR intervals are measured to determine
whether they are normal (0.12–0.20
seconds) and constant.
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18
INTERPRETATION OF CARDIAC
RHYTHMS
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19
The QRS intervals are measured to
determine whether they
are all within normal range (0.06–0.10
seconds).
INTERPRETATION OF CARDIAC
RHYTHMS
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20
Step 6. QT Interval
The QT interval is measured from the onset
of the QRS complex to the end of the T
wave.
QT interval represents the duration of
ventricular electrical systole, which includes
ventricular activation and recovery.
excessive extension of the QT interval is
strongly associated with ventricular
arrhythmias including Torsade de Pointes
(TdP), an acceleration in cardiac rhythm that
can lead to heart attack.
Dysrhythmias Originating in the
Atria
The SA node is the primary pacemaker, but if the atria
initiate impulses faster than the SA node, they become the
primary pacemaker.
Atrial rhythms are usually faster than 100 bpm and can
exceed 200 bpm.
When an impulse originates outside the SA node, the P
waves produced look different (flatter, notched, or peaked)
from the rounded P waves from the SA node.
This indicates that the SA node is not controlling the heart
rate.
These atrial impulses travel to the ventricles to initiate a
normal QRS complex after each P wave.
28
Dysrhythmias Originating in the
Atria
Atrial Fibrillation
ETIOLOGY.
aging (increases after age 60 and is the most common sustained
dysrhythmia)
History of cigarette smoking,
rheumatic or ischemic heart diseases,
heart failure,
hypertension,
pericarditis,
pulmonary embolism,
And some medications.
29
Atrial Fibrillation
1. Rhythm: irregularly irregular
2. Heart rate: atrial rate not measurable;
ventricular rate under 100 is controlled response;
greater than 100 is rapid ventricular response
3. P waves: no identifiable P waves
4. PR interval: none can be measured because no
P waves are seen
5. QRS interval: less than or equal to 0.10
seconds.
30
Atrial Fibrillation
SIGNS AND SYMPTOMS.
most patients feel the irregular rhythm.
Many describe it as palpitations or a skipping
heartbeat.
A patient’s radial pulse may be faint
because of a decreased stroke volume
If the ventricular rhythm is rapid and
sustained, the patient can go into left-sided
heart failure. 31
Atrial Fibrillation
THERAPEUTIC MEASURES.
The focus of AF treatment is to control rate, prevent
thromboembolism, and restore normal rhythm.
If the patient is unstable, synchronized cardioversion is
done immediately to try to return the heart to NSR.
For the patient who is stable, medications to control the
ventricular rate such as beta blockers, calcium channel
blockers, or digoxin are used.
Anticoagulant therapy is given to reduce thrombi, which
can cause a stroke. 32
Ventricular Dysrhythmias
PREMATURE VENTRICULAR CONTRACTION
Premature ventricular contractions (PVCs) originate in the ventricles
from an ectopic focus (a site other than the SA node).
The ventricles are irritable and fire prematurely, before the SA node
does.
When the ventricles fire first, the impulses are not conducted
normally through the electrical pathway.
This results in a wide (>0.10 seconds), bizarre QRS complex on an
ECG.
SIGNS AND SYMPTOMS.
PVCs may be felt by the patient and are described as a skipped
beat or palpitations. With frequent PVCs, cardiac output can be
decreased, leading to fatigue, dizziness, or more severe 34
Ventricular Dysrhythmias
PREMATURE VENTRICULAR CONTRACTION
THERAPEUTIC MEASURES.
Occasional PVCs do not usually require treatment.
However, if the PVCs are more than six per minute, regularly
occurring, multifocal, falling on the T wave (known as “R-on-T
phenomenon,” which can trigger life-threatening dysrhythmias),
Or caused by an acute MI, they can be dangerous. Antidysrhythmic.
drugs that depress myocardial activity are used to treat PVCs such
as amiodarone and beta blockers
35
Ventricular Dysrhythmias
Ventricular Tachycardia
The occurrence of three or more PVCs in a row is
referred to as ventricular tachycardia (VT)
VT results from the continuous firing of an ectopic
ventricular focus.
During VT, the ventricles rather than the SA node
become the pacemaker of the heart.
The pathway of the ventricular impulses is different
from normal conduction, producing a
wide (>0.10 seconds), bizarre QRS complex.
36
Ventricular Tachycardia
ETIOLOGY.
Myocardial irritability, MI, and
cardiomyopathy are common causes of VT.
Respiratory acidosis, hypokalemia, digoxin
toxicity, cardiac catheters, and pacing wires
can also produce VT.
37
Pathophysiology of Primary
Hypertension
Altered Renin-Angiotensin-
Aldosterone Mechanism
High plasma renin activity (PRA) results in the
increased conversion of angiotensinogen to
angiotensin I.
This alteration in the RAAS may contribute to
the development of hypertension.
38
Pathophysiology of Primary
Hypertension
Stress and Increased Sympathetic Nervous System
Activity.
Physiologic responses to stress, which are normally
protective, may persist to a pathologic degree, resulting in
a prolonged increase in SNS activity.
Increased SNS stimulation produces increased
vasoconstriction, increased HR, and increased renin
release.
Increased renin activates the RAAS, leading to elevated
BP.
People exposed to high levels of repeated psychologic
stress develop hypertension to a greater extent than those
who experience less stress.
39
Insulin Resistance and
Hyperinsulinemia
Insulin resistance is a risk factor in
the development of hypertension and
CVD.
High insulin levels stimulate SNS
activity and impair nitric oxide–
mediated vasodilation.
Additional pressor effects of insulin
include vascular hypertrophy and
increased renal sodium reabsorption.40
Nursing Management: Primary
HTN.
54
• Assessment
• Subjective data
• Objective Data
• Nursing Diagnosis
• Priority Diagnosis
• Collaborative problems
• Planning
• Overall Goals: Patient will:
• (1) achieve and maintain the goal BP; (2) understand
• and follow the therapeutic plan; (3) experience minimal or no
unpleasant side effects of therapy; and (4) be confident of the
ability to manage and cope with this condition.
HYPERTENSIVE CRISIS
59
• is a term used to indicate either a hypertensive
urgency or emergency. This is determined by the
degree of target organ disease and how quickly
the BP must be lowered.
• BP is severely elevated (often above 220/140 mm
Hg) with clinical evidence of target organ disease.
• Hypertensive urgency develops over days to
weeks. This is a situation in which a patient’s BP
is severely elevated (usually above 180/110 mm
Hg), but there is no clinical evidence of target
organ disease
Hypertensive urgencies usually do not require IV
medications but can be managed with oral agents.
HYPERTENSIVE CRISIS
60
Clinical Manifestations
A hypertensive emergency is often manifested as
hypertensive encephalopathy, a syndrome in
which a sudden rise in BP is associated with
severe headache, nausea, vomiting, seizures,
confusion, and coma.
The manifestations of encephalopathy are the
result of increased cerebral capillary permeability.
This leads to cerebral edema and a disruption in
cerebral function.
HYPERTENSIVE CRISIS
61
In treatment of hypertensive emergencies, the
mean
arterial pressure (MAP) is often used instead of BP
readings to guide and evaluate drug therapy.
Antihypertensive drugs administered IV have a rapid
(within seconds to minutes) onset of action. Assess
the patient’s BP and pulse every 2 to 3 minutes
during the initial administration of these drugs.