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Irregular fast atrial impulse
Lead II 25 mm/s. 10 mm = 1 mV
19.1 Atrial Arrhythmias
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257
The P waves are replaced by brillatory waves (f waves) resulting in a wavy
baseline. Atrial rate is 350–400bpm. There is no identiable P wave (Figs.19.9 and
19.10).
Box 19.2 Causes of Atrial Fibrillation
Rheumatic fever
Mitral stenosis
Thyrotoxicosis
Drugs: Adrenaline, digitalis
Cor pulmonale
Excessive consumption of tea, coffee, alcohol
Constrictive pericarditis
Lone atrial brillation
Acute myocardial infarction
Sick sinus syndrome
Cardiac surgery
Pulmonary embolism
Paroxysmal atrial brillation in young people after consumption of alcohol—
“Holiday Heart Syndrome”
Cardiomyopathy
Hypertensive heart disease
LA
RA
LV
RV
Fig. 19.9 Illustration of genesis of atrial brillation
Fig. 19.10 Atrial brillation. Note the irregularly irregular R-R interval. The P waves are replaced
by brillatory waves (wavy baseline)
Irregular R-R interval
No denite P waves visible (brillatory waves, also called f waves)
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19 Atrial Arrhythmias
Tips and Tricks
• Narrow complex tachycardia, irregularly irregular rhythm and absent P wave
indicate atrial brillation.
• In such a case if rhythm is regular, think of PAT.
• Vagal manoeuvres do not have any effect.
• In presence of severe cardiovascular compromise, electrical cardioversion
(100Ws) is the main treatment.
• Treatment of underlying causes like thyrotoxicosis, pericarditis and CHF is
equally important.
Self-Assessment Questions
1. Atrial extrasystoles, also known as premature atrial contractions (PACs), appear
as abnormal P′ waves on the ECG.True or false?
2. Atrial brillation is characterized by the absence of P waves on the ECG.True
or false?
3. Atrial extrasystoles are usually not followed by a compensatory pause on the
ECG.True or false?
4. Atrial utter is characterized by ‘sawtooth’ patterns on the ECG.True or false?
5. Mitral stenosis is an important cause of atrial brillation. True or false?
6. Characteristic ECG feature of PAT is:
a. Presence of brillatory waves b. Prolonged Q-T interval c. Absence of
QRS complexes d. Sudden onset and termination of tachycardia
7. In atrial extrasystole, the abnormal P wave on the ECG appears:
a. Before the QRS complex b. Between the QRS complex and T wave c.
After the QRS complex d. None of the above
8. In AF, the ventricular rhythm on the ECG is typically:
a. Regular b. Irregularly irregular c. Both of the above d. None of the above
9. ECG of wandering atrial pacemaker shows:
a. Wide QRS complex b. Irregularly irregular rhythm c. Presence of P waves
with different morphologies d. Absence of P waves
10. The treatment approach for PAT is:
a. Electrical cardioversion b. Medications to slow the heart rate c. Vagal
manoeuvres d. All of the above
Case Studies
1. A 45-year-old gentleman came for medical check-up. He had no history of CAD,
DM, HT.He was asymptomatic. His rhythm strip is given in Fig.19.11. Analyse
his rhythm strip. What is the treatment?
V5
19.1 Atrial Arrhythmias
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Lead II 25 mm/s. 10 mm = 1 mV
Fig. 19.11 Analyse the rhythm strip
V1
25 mm/s. 10 mm = 1 mV
Fig. 19.12 Analyse the rhythm strip
259
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 19.13 Analyse the rhythm strip
2. A 40-year-old lady suffering from hypothyroidism was taking 100 mcg of thy-
roxine daily. She had not checked her thyroid status for last oneyear. She complained of palpitation off and on for last 15days. On examination she had ne
tremor. Analyse her rhythm strip given in Fig.19.12. What is your diagnosis?
Which blood test will you advise?
3. A 35-year-old gentleman arrived in the casualty with history of sudden onset
palpitation for last 10 min. Similar episode of palpitation occurred 3 months
back which lasted for about 2min. He ignored it and did not consult any physician. His blood pressure was 110/70 mmHg, pulse rate was approximately
170bpm, regular with no special character. Analyse his rhythm strip given in
Fig.19.13. What is your diagnosis? How will you treat him?
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19 Atrial Arrhythmias
4. A 50-year-old gentleman arrived in the casualty with history of severe palpita-
tion. He did not suffer from palpitation in the past. He was mildly breathless.
There was no chest pain. He has no history of CAD, DM and HT.His BP was
90/60mmHg. Analyse his rhythm strip given in Fig.19.14. What is the diagnosis? What is the best treatment?
5. This ECG was given for spot diagnosis in examination for nal year medical
students. Analyse the rhythm strip given in Fig.19.15 and make your diagnosis.
Name ve conditions which can cause this.
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 19.14 Analyse the rhythm strip
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 19.15 Analyse the rhythm strip
19.1 Atrial Arrhythmias
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261
Answers
1. True 2. True 3. False 4. True 5. True 6. d 7. a 8. b 9. c 10. d
Case Studies
1. The rhythm strip in Fig.19.11 shows an atrial extrasystole. The fth P wave is
different from other P waves. It is a P′ wave. It is followed by a narrow QRS
complex which is premature in timing and it is followed by a pause. The pause
is incomplete. Rest of the rhythm strip does not show any gross abnormality.
He should be advised to reduce intake of tea and coffee. He should be further
advised to avoid stress and anxiety. A mild sedative may be prescribed for
about a week.
2. The rhythm strip in Fig.19.12 shows atrial bigeminy. Every normal PQRST
complex is followed by a premature PQRST complex. The P waves of these
complexes are different from the normal P waves. The second, fourth, sixth and
eighth complexes are premature atrial complexes or atrial extrasystoles. Also
note the incomplete pause after the atrial extrasystoles. This alternating sinus
beat and atrial extrasystole is known as atrial bigeminy.
The patient should be advised to get a free T3, free T4 and TSH tests done at
the earliest. Atrial bigeminy is most likely to be a side effect of thyroxine. Most
likely she will respond to reduction in the dose of thyroxine.
3. The rhythm strip in Fig. 19.13 shows paroxysmal atrial tachycardia. Note the
regular and rapid ventricular rate with absence of P wave and S-T segment
depression. The ventricular rate is 250bpm. This is a narrow complex tachycardia as the QRS duration is about 0.06s. The rhythm is regular. Hence, a regular
narrow complex tachycardia with absent P waves is diagnostic of paroxysmal
atrial tachycardia.
The patient is haemodynamically stable. He should be advised to perform
vagal manoeuvre like valsalva manoeuvre. If it does not revert back to sinus
rhythm, you can use IV adenosine which is the drug of choice for treatment.
6–12mg IV is given to terminate the arrhythmia.
Synchronized cardioversion with 50–100 joules is the main treatment for haemodynamically unstable patients of PAT.
4. The ECG in Fig.19.14 shows atrial utter with variable conduction. Carefully
note the saw tooth waves which have replaced the baseline. There is no isoelectric line. The QRS complexes are narrow and irregular.
The patient is not stable. He is suffering from hypotension. 25–50 joules DC
cardioversion should be carried out under mild sedation. 100 joules may also be
used as the initial shock strength as it is always successful and virtually never
harmful.
5. The ECG in Fig.19.15 shows atrial brillation. The P waves are not visible. The
rhythm is irregularly irregular. The QRS complexes are narrow. The baseline is
replaced by brillatory waves.
Five conditions that can cause atrial brillation are: rheumatic fever, thyro-
toxicosis, mitral stenosis, COPD and pulmonary embolism.
Antiarrhythmic drugs, anticoagulants and catheter ablation are the main treatment options in atrial brillation. Rate control, rhythm control and prevention of
stroke due to embolism are the main treatment goals.
Chapter 20
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Junctional andVentricular Arrhythmias
Learning Objectives
After studying this chapter, the reader will learn about:
• AV junctional rhythm
• Premature junctional complex
• Junctional rhythm
• Ventricular extrasystoles
• Ventricular tachycardia
• Ventricular utter
• Ventricular brillation
• Idioventricular rhythm
• Accelerated idioventricular rhythm
• Ventricular asystole
20.1 AV Junctional/Nodal Rhythm
An impulse may originate from the AV junction instead of the SA node. It is called
AV junctional/nodal rhythm. It must be kept in mind that the rhythm does not originate from the AV node proper because it has no property of generation of impulse.
The impulse may be conducted to the atria and the ventricles or the impulse may be
conducted to the ventricles only and the retrograde conduction to the atria may be
blocked.
When the impulse is conducted to both the atria and the ventricles, the ventricular activation proceeds along the normal pathway resulting in normal QRS complex.
The conduction to the atria occurs in a retrograde manner, i.e. the direction of depolarization is reversed resulting in inverted P waves in leads II, III and aVF and
Ltd. 2024
T. K. Koley, Rapid Review of ECG,
https://doi.org/10.1007/978-981-99-9116-7_20
263© The Author(s), under exclusive license to Springer Nature Singapore Pte
264
25 mm/s. 10 mm = 1 mVLead II
Impulse originates near AV node
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20 Junctional andVentricular Arrhythmias
upright in lead aVR.This P wave may precede or follow or may be hidden in the
QRS complex. This depends upon the relative velocity of the anterograde and retrograde conduction. This nodal rhythm may be in the form of AV nodal extrasystole,
AV nodal escape beat, paroxysmal AV nodal tachycardia or idionodal tachycardia.
In all these arrhythmias, the features are similar to that described in atrial arrhythmias except that the P waves will be inverted and may appear before, after or hidden
in QRS complex.
20.1.1 Premature Junctional Complex
The ECG features of premature junctional complex (PJC) are similar to that of premature atrial complex except that the P′ wave will be inverted. It may appear before,
after or hidden in the QRS complex (Fig.20.1).
20.1.2 Junctional Rhythm
Junctional rhythm arises from AV junction at a rate between 40 and 60bpm. This
rhythm occurs when the discharge rate of SA node falls and the AV junction takes
over as the dominant pacemaker (Figs.20.2 and 20.3). The ECG features are:
Fig. 20.1 Premature junctional complex. Note the inverted P′ wave of fourth complex which is
followed by a pause
LA
RA
LV
RV
Fig. 20.2 Illustration of genesis of junctional rhythm. The impulse originates near AV node and
results in inverted P wave that appears after the R wave. The rate is between 40 and 60bpm
R
T
P
Inverted P wave after the R wave
R
T
P
R
T
P
Lead II 25 mm/s. 10 mm = 1 mV
20.1 AV Junctional/Nodal Rhythm
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Lead II
25 mm/s. 10 mm = 1 mV
Fig. 20.3 Junctional rhythm. Note that the P′ waves are not seen as they are hidden in the QRS
complexes. The QRS complexes are of normal duration. The rate is 48bpm
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 20.4 Accelerated junctional rhythm. Note the inverted P′ waves before QRS complexes and
the heart rate is 79bpm
265
Fig. 20.5 Junctional tachycardia. The heart rate is 136bpm
• The P′ waves are inverted and either appear before, after or are hidden in QRS
complexes.
• The QRS duration is normal.
• The P′-R interval will be less when P′ waves appear before the QRS complex.
A junctional rhythm is called accelerated junctional rhythm when the rate is between
60 and 100bpm (Fig.20.4). Rest of the ECG features are same. In junctional tachycardia, the rate is more than 100bpm and rest of the ECG features are like junctional
rhythm (Fig.20.5).
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Tips and Tricks
• You should suspect junctional origin of the rhythm if P wave is inverted or absent
and the QRS complexes are of normal duration.
20 Junctional andVentricular Arrhythmias
20.2 Ventricular Arrhythmia
Ventricular arrhythmias originate from the ventricles. The electrical impulse does
not follow normal pathway and depolarizes one ventricle before the other. The ventricular arrhythmias are thought to be due to altered automaticity, triggered activity
or re-entry. The common types of ventricular rhythm disturbances are the following:
• Ventricular extrasystoles
• Ventricular tachycardia
• Ventricular utter
• Ventricular brillation
• Idioventricular rhythm
• Accelerated idioventricular rhythm
• Ventricular asystole
Tips and Tricks
• Ventricular origin of the rhythm should be suspected whenever there is broad
QRS complex with T wave abnormality.
20.2.1 Ventricular Extrasystoles
Ventricular extrasystoles also called ventricular premature complex (VPC) originate from the premature discharge of an ectopic focus either in right or left ventricle. It is the commonest ventricular arrhythmia. It is usually seen in almost all types
of heart disease. Sometimes it may be seen in normal persons but in them one
should carefully search for an underlying cardiac disease. The ventricular extrasystole may be unifocal (arising from single focus) or multifocal (arising from multiple
foci). Ventricular extrasystoles occurring in pairs or at a frequent rate may lead to
ventricular tachycardia or more serious ventricular brillation. If it occurs after
myocardial infarction, it carries poor prognosis. Digitalis is a frequent cause of
ventricular extrasystoles. The causes of ventricular extrasystoles are summarized in
Box 20.1.
Only one impulse originates in right ventricle
20.2 Ventricular Arrhythmia
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Box 20.1 Causes of Ventricular Extrasystoles
Coronary artery disease
Digitalis toxicity
Electrolyte imbalance
Acid base disturbance
Congestive heart failure
Hypoxia
Acute myocardial infarction
During or after reperfusion therapy or angioplasty
Cardiac surgery
Cardiomyopathy
The extrasystole arises from an irritable focus in the myocardium of the ventricle
(Fig. 20.6). This impulse then activates the ventricles and this impulse does not
depolarize the SA node and hence, the sinus rhythm is maintained. However, the
next sinus beat after the extrasystole will not be able to activate the ventricles
because they are in a refractory state. The ventricle will respond to the next sinus
impulse. This will lead to a pause, which is known as compensatory pause. However,
if the sinus rate is slow, then a ventricular extrasystole can occur between two normal sinus beats without any change in the R-R interval. This is known as ‘interpolated beat’. Sometimes the ventricular extrasystole may be so premature that it
coincides with the apex or distal limb of T wave of the preceding QRST complex.
This is called ‘R on T phenomenon’ and indicates the highly excitable state of the
ventricles and may lead to ventricular tachycardia or brillation.
Ventricular extrasystole is diagnosed by the following features:
The beat arises prematurely, i.e. it occurs earlier than the anticipated QRS
complex.
The P wave is absent in the extrasystoles.
The QRS complex is wide, bizarre with the S-T segment and T wave in opposite
direction to the dominant QRS deection. The duration of QRS complex is more
than 0.12s.
The compensatory pause is complete, i.e. the R-R interval between the two sinus
beats preceding and following the ventricular extrasystoles is double the R-R interval between two normal sinus beats (Figs.20.7 and 20.8).
LA
RA
Fig. 20.6 Illustration of genesis of ventricular extrasystole. Note that the impulse originates in the
right ventricle and does not travel via the normal conducting system, thus producing the broad and
bizarre QRS complex followed by compensatory pause
LV
RV
R-R
More than twice R-R
Compensatory pause
Ventricular extrasystole
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