Cardiac arrhythmias

Question 1

Define bradyarrhythmia.

Answer 1

Resting heart rate of <60 bpm

Question 2

Define tachyarrhythmia.

Answer 2

Resting heart rate of >100 bpm

Question 3

Define supraventricular arrhythmia.

Answer 3

Arrhythmias that originate in the sinoatrial node, atrial myocardium, or atrioventricular node (with a regular QRS complex)

Question 4

Define ventricular arrhythmia.

Answer 4

Arrhythmias that originate below the atrioventricular node (with a wide QRS complex)

Question 5

List the types of bradyarrhythmias with an atrial origin.

Answer 5

1. Respiratory sinus arrhythmia
2. Sinus bradycardia
3. Sinus pause or arrest
4. Tachycardia-bradycardia syndrome

Question 6

What is the cause(s)/mechanisms of respiratory sinus arrhythmia?

Answer 6

Physiological, particularly in youths

Question 7

What are the main ECG findings in respiratory sinus arrhythmia?

Answer 7

1. Minor changes in R-R interval during respiration

(Reduction during inspiration and increase during expiration)

Question 8

What is the cause(s)/mechanisms of sinus bradycardia?

Answer 8

1. Physiological (athletes)
2. Sinus node dysfunction
3. Drugs: beta blocks, CCBs

Question 9

What are the main ECG findings in sinus bradycardia?

Answer 9

1. Rate <60 bpm

2. Normal p wave before every QRS complex

Question 10

What is the cause(s)/mechanisms of sinus pause/arrest?

Answer 10

1. Physiological

2. Underlying cardiovascular disease (sick sinus syndrome)

Question 11

What are the main ECG findings in sinus pause/arrest?

Answer 11

1. Transient (sinus pause) or complete (sinus arrest) absence of P wave
2. Often with an escape rhythm

Question 12

What is the cause(s)/mechanisms of tachycardia-bradycardia syndrome?

Answer 12

1. Abnormal supraventricular impulse generation and conduction (sick sinus syndrome)

Question 13

What are the main ECG findings in tachycardia-bradycardia syndrome?

Answer 13

1. Intermittent tachyarrhythmias and bradyarrhythmias

Question 14

List the types of bradyarrhythmias with an AVN origin.

Answer 14

1. 1st degree AV block
2. 2nd degree (type I) AV block
3. 2nd degree (type II) AV block
4. 3rd degree AV block

Question 15

What are the causes/mechanisms of 1st degree AV block?

Answer 15

1. Physiological
2. Increased vagal tone
3. Drugs: beta blockers, CCBs

Question 16

What are the ECG findings in 1st degree AV block?

Answer 16

PR interval >200ms

Question 17

What are the causes/mechanisms of 2nd degree AV block?

Answer 17

1. Drugs: digoxin, beta blockers, CCBs
2. Increased vagal tone
3. Sinoatrial conduction disease
4. Right coronary infarction

Question 18

What are the ECG findings in 2nd degree (type I) AV block?

Answer 18

Progressive lengthening of the PR interval until a beat is dropped

Question 19

What are the ECG findings in 2nd degree (type II) AV block?

Answer 19

Irregular dropped beats

Question 20

What are the causes/mechanisms of 3rd degree AV block?

Answer 20

Complete block: no communication between atria + ventricles (contraction occurs independently without organised electrical transmission via AVN)

Question 21

What are the ECG findings in 3rd degree AV block?

Answer 21

AV dissociation - no relationship between P waves and QRS complexes

Question 22

List the types of supraventricular tachyarrhythmias with an atrial origin.

Answer 22

1. Supraventricular premature beats
2. Sinus tachycardia
3. Atrial flutter
4. Atrial fibrillation
5. Focal atrial tachycardia
6. Multifocal atrial tachycardia

Question 23

What are the causes/mechanisms of supraventricular premature beats?

Answer 23

1. Physiological
2. Electrolyte imbalances
3. Underlying cardiovascular disease

Question 24

What are the ECG findings in supraventricular premature beats?

Answer 24

P wave abnormalities or absent P waves

Question 25

What are the causes/mechanisms of sinus tachycardia?

Answer 25

Sympathetic activation or vagal withdrawal on the SA node, e.g.: 1. exercise 2. fever 3. hypovolaemia 4. anaemia 5. hyperthyroidism 6. conditions associated with catecholamine release (phaeochromocytoma)

Question 26

What are the ECG findings in sinus tachycardia?

Answer 26

1. Gradual onset 2. Regular rhythm 3. Rate: max is usually 180 bpm 4. Normal P wave 5. Narrow QRS complex

Question 27

What are the causes/mechanisms of atrial flutter?

Answer 27

Macroreentrant rhythms within atria

Question 28

What are the ECG findings in atrial flutter?

Answer 28

1. Regular rhythm 2. Atrial rate of 250-350; Ventricular rate of <200 3. P waves: sawtooth appearance of regular P waves, especially in leads II, III, and aVF 4. Narrow QRS complex

Question 29

What are the causes/mechanisms of atrial fibrillation?

Answer 29

There are multiple conditions (cardiac, non-cardiac) and lifestyle factors that can predispose an individual to AF

Question 30

What are the ECG findings in atrial fibrillation?

Answer 30

1. Irregularly irregular rhythm 2. Atrial rate of 350-450; Ventricular rate <200 3. P waves are indiscernible 4. Narrow QRS complex

Question 31

What are the causes/mechanisms of focal atrial tachycardia?

Answer 31

Discharge from a single ectopic focus in the atrium

Question 32

What are the ECG findings in focal atrial tachycardia?

Answer 32

1. Very abrupt onset 2. Regular rhythm 3. Rate 150-250 bpm 4. P wave morphology depends on the site of the ectopic focus 5. Narrow QRS complex

Question 33

What are the causes/mechanisms of multifocal atrial tachycardia?

Answer 33

1. Discharge from multiple ectopic foci in the atrium 2. Associated with pulmonary disorders (COPD exacerbation, PE), cardiac conditions (CHF exacerbation), and treatment with theophylline

Question 34

What are the ECG findings in multifocal atrial tachycardia?

Answer 34

1. Very abrupt onset with rate variation 2. Irregularly irregular rhythm 3. Rate 150-250 bpm 4. Discernible P waves with ≥3 different morphologies 5. Narrow QRS complex