A 51 year old man was referred for investigation of presumed valvar aortic stenosis. A murmur had been noted as a child but he had developed normally and was entirely asymptomatic. He had had two episodes of infective endocarditis successfully treated medically in 1968 and 1977. He was currently on no medication. Annual echocardiography had shown a possible bicuspid aortic valve with a pressure gradient of 30 mm Hg and a hypertrophied left ventricle with good systolic function.

Examination revealed a fit man with a blood pressure of 140/90 mm Hg in the right arm but only 110 mm Hg systolic in the left, suggesting a preferential streaming up the innominate artery. His pulse was regular at 68 beats/min, which was slow rising in quality. His jugular venous pressure was …