Systolic pressure gradients across the aortic valve and in the ascending aorta

Abstract

Left ventricular and aortic pressure pulses and the pressure gradient across the aortic valve were recorded in anesthetized and unanesthetized dogs. Aortic pressure recorded immediately above the valve increased 5–15 msec before it was exceeded by left ventricular pressure. The maximum systolic pressure gradient occurred in early systole and remained positive throughout the ejection period. When aortic pressure was recorded 1–3 cm distal to the valve, these pressure pulse relationships were altered so that 1) the rise in aortic pressure was delayed, 2) the early systolic maximum pressure gradient was increased, and 3) aortic pressure exceeded ventricular pressure during the latter half of systole. The changes in early systole are due to a delay in the pulse wave reaching the more distal recording site. The mean systolic pressure gradient between two sites within the ascend-ing aorta was found to be negative, i.e., opposite to the direction of forward flow. The negative pressure gradient probably accounts for the reversal of the transvalvular pressure gradient in late systole when aortic pressure was recorded distal to the valve.