ECG rhythms

Question 1

What is normal sinus rhythm defined by? (2)

Answer 1

P wave for each QRS and vice versa

PR interval

Question 2

What is sinus arrythmia defined by?

Answer 2

Meets all criteria for sinus rhythm but rhythm itself is irregular because of changes due to respiration

Question 3

ECG features of atrial fibrillation (2)

Answer 3

Disorganised atrial activity- absent P waves

Irregular QRS complexes

Question 4

Cause of atrial flutter

Answer 4

Re-entry circuit within the atria resulting in an atrial rate of around 300bpm

Question 5

ECG features of atrial flutter (2)

Answer 5

Sawtooth baseline best seen in V1 or II

Ventricular rate usually a division of 300 (e.g. 150, 100, 75)

Question 6

Atrial flutter is a type of what?

Answer 6

Narrow complex tachycardia

Question 7

What is junctional rhythm and how does it appear on ECG?

Answer 7

Electrical impulse begins in the AV node and travels retrograde. Results in inverted P waves after the QRS

Question 8

What is supraventricular tachycardia?

Answer 8

Narrow complex tachy that originates above or involves the AV node

Question 9

ECG features of SVT?

Answer 9

Regular narrow complex tachy. Often no clear P waves

Question 10

How does the morphology of an atrial eptopic differ from a normal P wave?

Answer 10

Narrow and pointed (compared to broad and flat)

Question 11

What are the defining features of ventricular rhythms? (2)

Answer 11

They are always broad complex and always pathological

Question 12

What are ventricular complexes?

Answer 12

Heartbeat initiated by Purkinje fibres

Question 13

What is a) bigeminy and b) trigeminy?

Answer 13

a) 1 sinus beat + one ventricular premature complex

b) 1 sinus beat + two VPCs

Question 14

What is ventricular tachycardia?

Answer 14

Regular broad complex tachy

Question 15

What can polymorphic VT (e.g. torsades de point) be confused with?

Answer 15

ventricular fibrillation

Question 16

What are polymorphic VTs often associated with?

Answer 16

Long QT syndrome

Question 17

What is a fusion beat?

Answer 17

When a normal beat fuses with a VT complex

Question 18

What is a capture beat?

Answer 18

A normal QRS between abnormal beats

Question 19

What are fusion beats and capture beats both “proof” of?

Answer 19

Independent rhythms in atria and ventricles

Question 20

Why can it sometimes be difficult to distinguish ventricular rhythms from supraventricular rhythms + bundle branch block?
How can these be distinguished?

Answer 20

Both give you a broad QRS complex.

Good predictor of VT is pre-existing coronary disease. Capture and fusion beats are always VT

Good predictorof SVT is pre-existence of LBBB/RBBB