Contour changes of the aortic pulse during propagation

Abstract

Changes in aortic pulse contour were mapped by moving a recording sound through the aorta of lightly anesthetized dogs. The initial anacrotic slope of the ascending aortic (root) pulse usually traverses the arch and the thoracic aorta unchanged, but is often steepened in the abdominal aorta. The break in this slope occurs at a progressively higher pressure level as the pulse moves outward. Starting in the descending arch, a new wave, not seen in the root pulse, rises from the broad top of the systolic portion of the pulse. As the pulse moves peripherad, the peak of this wave moves progressively earlier until finally it may merge with the anacrotic slope itself. Hence the peaks are approximately simultaneous for all parts of the aorta beyond the arch, i.e. they are ‘standing waves.’ In a few cases, the root pulse shows a small but clear negative trough coincident with this peripheral pulse peak. In late systole or early diastole, the root pulse shows a pressure plateau or even a rise, while the pressure in the peripheral pulses is falling sharply to make a trough. Following this, there may be one or more reciprocal oscillations between the root and a peripheral aortic pulse. While standing waves are commonly seen in the dog, they are not developed in some cases, but the pulse pressure may still show an augmentation.