Inspiratory right ventricular outflow obstruction in a patient with hypertrophic cardiomyopathy.

A patient with familial hypertrophic cardiomyopathy with exertional near syncope is reported. Intra-right ventricular obstruction was demonstrated by hemodynamic studies during inspiration and the Valsalva maneuver with systemic hypotension. Improvement occurred following the administration of propranolol. It was suggested that syncope might be precipitated by hemodynamic changes such as a high output state and a depressed cardiac volume in relation to intra-right ventricular obstruction in patients with hypertrophic cardiomyopathy.