12 lead ECGs

Question 1

Causes of Atrial arrhythmias

Answer 1

ischaemia

hypoxia

Question 2

ECG features in atrial arrhythmias

Answer 2

normal QRS
P waves that differ in appearance from sinus P waves
abnormal shortening or prolonged PR intervals

Question 3

Atrial Fibrillation

Answer 3

multiple areas of re-entry in atria or ectopic atrial pacemakers
chaotic impulses too numerous to be conducted by AV node through ventricles
P waves absent

Question 4

Atrial Flutter

Answer 4

single atrial focus
results from circus re-entry and possibly automaticity
AV node fails to allow conduction of all impulses to the ventricles therefore the ventricular rate is slower
expressed as a ratio

Question 5

First degree AV block

Answer 5

when the electrical impulse is delayed through the AV node

PR interval is greater than 0.20 seconds

Question 6

Second degree AV block - Mobitz type 1

Answer 6

progressive delay in the cnoduction of impulses through the AV node until conduction is completely blocked
progressive prolongation of PR interval prior to failed/missed conduction

Question 7

Mobitz II

Answer 7

intermittent block of conduction occurs in one bundle branch and a complete block occurs in the other
QRS abnormal due to bundle branch block

Question 8

3rd degree block

Answer 8

due to disruption of the AV pathway to the ventricles
no conduction of impulses from the atria to the ventricles
p waves and QRS are not related

Question 9

PVCs

Answer 9

originates in an ectopic pacemaker in the ventricle, abnormally wide and bizarre QRS complex
Unifocal: single ectopic site
multifocal: different ectopic sites
bigeminy: every 2nd complex is a PVC