Atrial flutter. Electrocardiographic, vectorcardiographic and echocardiographic correlation

The duration, contour, and amplitude of atrial flutter wave (f) was studied by electrocardiogram (ECG) and vectorcardiogram (VCG) in 32 patients and was related to the size of the left atrium (LA) measured by the echocardiogram (E). The following ECG parameters were analyzed: (1) the duration of left atrial depolarization, i.e., LA wave; (2) the amplitude of LA wave; (3) the surface area of LA wave; (4) maximum amplitude (A) of f in Leads 2 and V1. There was good correlation between LA size and the duration of depolarization and surface area (p less than 0.01), but the maximum amplitude of the f wave in Leads 2 and V1 failed to predict LA size. The post-conversion sinus P wave showed abnormal LA depolarization time (P greater than 0.12 sec.) in 62 per cent of patients with enlarged left atrium (ELA) and in 43 per cent of patients with normal size LA (NLA). The VCG of the flutter wave revealed two patterns, (1) an eliptical smooth fsE loop in 63 per cent of patients with NLA, and (2) distorted fsE loop in 67 per cent of patients with ELA. Both VCG patterns were subdivided in two subgroups according to the number and location of conduction delays. The VCG of post-conversion P wave confirmed conduction delays in both groups. We conclude that both the size of the left atrium and conduction delays play a basic role in the duration and contour of left atrial wave.