The Brockenbrough-Braunwald-Morrow sign.

Hypertrophic cardiomyopathy is a relatively common genetic disorder and usually asymptomatic. However, approximately 25% of patients develop left ventricular outflow obstruction and can develop angina, syncope, or congestive heart failure. Initiation and titration of beta-blockade usually results in symptomatic improvement. Patients with medically refractory symptoms can see further symptomatic improvement and relief of obstruction with either surgical myectomy or alcohol septal ablation (ASA). Although surgical myectomy has been the gold standard, ASA has been shown in nonrandomized studies and a meta-analysis to be comparable. In patients undergoing ASA without a rest obstruction, the Brokenbrough-Braunwald-Morrow sign can be used to accurately determine the degree of left ventricular outflow tract (LVOT) obstruction prior to, during, and after ASA.