Echocardiographic Brockenbrough-Braunwald-Morrow sign.

The Brockenbrough-Braunwald-Morrow sign is the paradoxical decrease in pulse pressure during the post-extrasystole beat seen in patients with hypertrophic obstructive cardiomyopathy. We present a case of intermittent left ventricular outflow tract obstruction and secondary mitral regurgitation resulting from post-extrasystolic potentiation following a premature atrial beat, demonstrating using echocardiography the mechanism behind this sign.