P loops during common and uncommon atrial flutter in man

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Atrial flutter lacks a precise definition.
• The 'common' type was described by Lewis in 1913; 'uncommon' types are less frequent.

Purpose of the Study:

• To define and differentiate common and uncommon atrial flutter using isolated P loop vectorcardiography.
• To analyze the vectorcardiographic characteristics of different atrial flutter patterns.

Main Methods:

• Studied 16 cases of 'common' and 6 of 'uncommon' atrial flutter.
• Utilized isolated P loop vectorcardiography.
• Monitored atrial rates and response to vagal maneuvers.

Main Results:

• Common atrial flutter (250-330 bpm) showed caudad-cephalad P loop orientation with specific right and left atrial forces.
• Uncommon flutter (250-300 bpm) did not meet all criteria for common flutter and displayed diverse loop patterns.
• One case met criteria for left atrial flutter.

Conclusions:

• Vectorcardiography provides detailed data on atrial flutter patterns.
• Distinct vectorcardiographic features differentiate common from uncommon atrial flutter.
• The underlying mechanisms of flutter were not identified by this method.