Idiopathic hypertrophic subaortic stenosis presenting as cough syncope.

In a patient with idiopathic hypertrophic subaortic stenosis, syncope developed as a result of a sustained decrease in aortic pressure induced by severe cough paroxysms. Treatment with propranolol was effective in abolishing the syncopal episodes, by reducing the post-tussive gradient and facilitating a more rapid return to normal of aortic pressure. Post-tussive syncope in IHSS may result from both an unusually strong cough paroxysm and augmented left ventricular outflow obstruction consequent to reflex sympathetic stimulation.