Effects of amyl nitrite on coronary arterial blood flow velocity in man

Abstract

Instantaneous coronary arterial phasic blood flow velocity was measured in 21 patients (8 with coronary artery disease) after amyl nitrite inhalation. Measurement was made with use of a Doppler ultrasonic flowmeter catheter positioned at the ostia of the coronary arteries. In all cases, there was an appreciable increase in diastolic coronary arterial phasic blood flow velocity within 10 seconds. Flow velocity increased from 50 to 216 percent over control values after administration of amyl nitrite. Subjects with marked obstructive coronary artery disease had decreased peak coronary arterial phasic blood flow velocity responses when compared with control subjects. Atrial pacing to heart rates attained with amyl nitrite alone resulted in no appreciable increase or decrease in coronary arterial phasic blood flow velocity, thus showing that increase in the latter was not dependent on this action of the drug. Furthermore, increase occurred before appearance of the arterial hypotensive effect of amyl nitrite. The presence of an increase in coronary arterial phasic blood flow velocity after administration of a drug with demonstrable coronary vasodilating action strongly suggests that one of the important attributes of nitrites is their ability to increase coronary arterial blood flow.