Echocardiographic findings in atrial flutter.

Echocardiographic studies were performed in 22 patients with atrial fibrillation and atrial flutter. In atrial flutter, the echocardiograms consistently demonstrated regular undulatory waves of the posterior left atrial wall and upper left interventricular septum coinciding with each flutter wave of the electrocardiogram. The mitral valve was slightly reopened by each flutter wave occurring after diastolic mitral closure. The phonocardiogram simultaneously recorded with the echocardiogram showed only occasional atrial sounds. Coarse atrial fibrillation produced undulatory low frequency motion of both leaflets of the mitral valve during diastole. Atrial fibrillation with fine fibrillatory waves failed to show any significant and constant undulations of the left atrial wall and upper left interventricular septum. Echocardiographic evaluation of patients with atrial flutter could have diagnostic implications in doubtful cases with nondiagnostic electrocardiograms.