Common Disturbances of Cardiac Rhythm

Question 1

What is the difference between a sinus and non-sinus bradycardia?

Answer 1

Sinus bradycardia is a slow HR where each QRS is preceded by a P-wave.

Question 2

Describe the differences in P-P intervals for sinus arrest and sino-atrial block.

Answer 2

In sinus arrest the P-P intervals do not match up. There is a prolonged pause between P-wave activity. SA block has pauses that are consistently 2XP-P or more.

Question 3

First degree AV block is where there is a delay in QRS following a p-wave. There are two types of second degree block. Describe the relationship between the P-wave and the QRS for the two types.

Answer 3

Type I Second degree AV (Wenckebach) – the p-wave is married to the QRS but there is an increase in the duration and then there is a sudden drop in the P-R interval and the P-wave is close again. Type II Second degree AV block. Requires pacemaker. There is a regular P-R interval until there is no QRS. Syncope

Question 4

Name five causes of atrial fibrillation.

Answer 4

Ischaemic heart disease Hypertensive heart disease Rheumatic heart disease Thyrotoxicosis Alcohol misuse (acute or chronic) Cardiomyopathy (dilated or hypertrophic) Sick sinus syndrome Postcardiac surgery Chronic pulmonary disease Idiopathic (lone)

Question 5

Describe the key features of atrial fibrillation on an ECG.

Answer 5

absent P waves fine baseline “f wave” oscillations irregular ventricular complexes

Question 6

Saw-toothed waves due to re-entry into the right atrium would be?

Answer 6

Atrial Flutter