Interatrial mechanical dyssynchrony shown by tissue doppler imaging during atrial flutter.

Although regular supraventricular tachycardia is traditionally classified on the basis of P-wave morphology, diagnostic accuracy is limited to information obtained from surface electrocardiography. Intracardiac electrophysiology is a conclusive although invasive diagnostic method. We report a case of regular supraventricular tachycardia with a heart rate of 162 bpm. M-mode echocardiography of the interatrial septum clarified both the atrial rate and the ventricular response ratio. Tissue Doppler M-mode imaging demonstrated the delay between the posterior wall motion of the left and right atrium. Although it deserves further study, transthoracic echocardiography may provide useful information in addition to electrocardiography.