Brockenbrough–Braunwald–Morrow sign and Valsalva manoeuvre: how to unmask dynamic left ventricular outflow tract obstruction

A 71-year-old patient with Influenza A pneumonia presented with resting chest pain. Rise in cardiac troponin T (peak 188 ng/L, normal <14.0 ng/L) and diffuse downsloping electrocardiographic ST-depression allowed the diagnosis of non-ST-elevation myocardial infarction to be made. On echocardiography, there was left ventricular (LV) hypertrophy (septum 21 mm, posterior wall 15 mm; Supplementary data online, Video S1); LV ejection fraction was 70%, without segmental wall motion abnormality. LV outflow maximal velocity was 2.2 m/s (Panel A), with incomplete systolic anterior motion (SAM) of the mitral valve (Panel C) and mild mitral regurgitation (Panel E). However, during the beat following a premature ventricular contraction (*), the SAM became complete (arrowhead, Panel D), and the peak velocity was 7 m/s (Panel A), with the occurrence of severe mitral regurgitation (Panel F, Supplementary data online, Video S2). The Valsalva manoeuvre also provoked a 7 m/s LV outflow tract peak velocity (Panel G). Coronary angiography demonstrated left main coronary artery and right coronary artery stenosis. Simultaneous LV and aortic pressure recording demonstrated a 120 mmHg peak-to-peak pressure gradient during the first sinus beat after the premature contraction (*) and reduced pulse pressure (double arrows) (Panel B). Coronary artery bypass grafting and septal myectomy were subsequently performed.