Dual echocardiographic determination of atrial contraction sequence in atrial flutter and other related atrial arrhythmias.

We have applied the new technique of dual echocardiography to determine the sequence of atrial contraction as reflected in the simultaneously recorded movements of the tricuspid and mitral valves. The study group included 29 normal subjects and 23 patients with either atrial flutter, coarse atrial fibrillation or atrial tachycardia with block. In normal individuals, right atrial contraction preceded left atrial contraction, with an average interatrial contraction time of 17 +/- 8 msec. In contrast, the atrial contraction sequence was reversed in atrial flutter, with left preceding right atrial contraction and a prolonged interatrial contraction time of 82 +/- 20 msec. In two patients with atrial tachycardia with block, atrial contraction was either simultaneous or left preceded right atrial contraction by a brief interval. The sequence of atrial excitation, as determined by electrode catheter recordings from the right and left atria in one patient with atrial flutter and one patient with normal sinus rhythm, was the same as the contraction sequence. Left atrial pacing reversed both excitation and contraction sequences. After cardioversion of three patients from atrial flutter to normal sinus rhythm, interatrial contraction time was shortened but remained longer than in normal subjects, suggesting an interatrial conduction disturbance in patients with atrial flutter. In coarse atrial fibrillation, the contraction sequence varied. Significant motion of both mitral and tricuspid valves coincident with fibrillary waves occurred frequently, especially when the fibrillary waves were coarse and regular. Dual echocardiography permits the noninvasive determination of the sequence of atrial contraction and excitation, and may be useful in studying the characteristics of atrial arrhythmias.