Sunday, 13 November 2016

Atrial Flutter


Atrial flutter is an abnormal heart rhythm that occurs in the atria of the heart. When it first occurs, it is usually associated with a fast heart rate or tachycardia (beats over 100 per minute), and falls into the category of supra-ventricular tachycardias. While this rhythm occurs most often in individuals with cardiovascular disease (e.g. hypertension, coronary artery disease, and cardiomyopathy) and diabetes mellitus, it may occur spontaneously in people with otherwise normal hearts. It is typically not a stable rhythm, and frequently degenerates into atrial fibrillation (AF). However, it does rarely persist for months to years.

Atrial flutter was first identified as an independent medical condition in 1920 by the British physician Sir Thomas Lewis (1881–1945) and colleagues.

There are two types of atrial flutter, the common type I and rarer type II.  Most individuals with atrial flutter will manifest only one of these. Rarely someone may manifest both types; however, they can only manifest one type at a time.

Type I

Type I atrial flutter, also known as common atrial flutter or typical atrial flutter, has an atrial rate of 240 to 340 beats/minute. However, this rate may be slowed by antiarrhythmic agents.
  • Counterclockwise atrial flutter (known as cephalad-directed atrial flutter) is more commonly seen. The flutter waves in this rhythm are inverted in ECG leads II, III, and aVF.
  • The re-entry loop cycles in the opposite direction in clockwise atrial flutter, thus the flutter waves are upright in II, III, and aVF.

Type II
Type II flutter follows a significantly different re-entry pathway to type I flutter, and is typically faster, usually 340-440 beats/minute. Left atrial flutter is common after incomplete left atrial ablation procedures.

Modified Lead Placement for Atrial Flutter:

A Lewis Lead (also called the S5 lead) is a modified ECG lead used to detect atrial flutter waves when atrial flutter is suspected clinically, based on signs and symptoms, but is not definitely demonstrated on the standard 12 lead ECG. In order to create the Lewis Lead, the right arm electrode is moved to the manubrium adjacent to the sternum. Then the left arm electrode is moved to the right, fifth intercostal space adjacent to the sternum. The left leg electrode is placed on the right lower costal margin. The Lewis Lead is then read as Lead I on the ECG and, since in most patients it will be roughly perpendicular to the wave of ventricular depolarization, atrial flutter waves may be more apparent.