Atrial flutter with varying conduction

ECQ Quiz 11

The flutter waves are seen at a rate of around 300 minute and ventricular rate varies between 75 – 100/minute. The flutter waves are inverted in leads II, III and aVf, suggestive of typical atrial flutter. Atrial flutter is quite sensitive to cardioversion and can be reverted with small energy of direct current cardioversion. The flutter can be typical or reverse typical, depending on the re-entry circuit within the atrium. Usual form of flutter is isthmus dependant and can be ablated by radiofrequency catheter ablation. Atrial flutter can also occur due to re-entry around a scar, usually surgical.

Digoxin can convert atrial flutter to atrial fibrillation. Usually the conduction ratio is 2:1 and the ventricular rate will be 150 per minute with a typical flutter rate of 300 per minute. If quinidine is given as a single drug for atrial flutter, it can increase the ventricular rate as it reduces the flutter rate to around 200 per minute and the conduction becomes 1:1. Hence an additional AV nodal blocking drug is needed when quinidine is given for the treatment of atrial flutter. Of course this is not a concern now a days as quinidine is not available in most regions!