Dynamic Changes in Arterial Pressure Pulses Produced by a Simulated Saccular Aneurysm

Publisher Website
Google Scholar
Abstract
As a first approach to a study of the effects of a saccular aortic aneurysm on the pressure pulses of the arterial system, a compression chamber was introduced into the dog''s descending thoracic aorta. Proceeding from the general observation that an aneurysm reduces the amplitude of the peripheral pulse to less than that of the central pulse, a compression chamber of sufficient size to accomplish this was developed. This required a surprisingly large chamber which according to rough calculations should double the distensibility of the whole system. The following dynamic alterations in pressure pulses recorded from the aorta, the femoral artery and the compression chamber were considered most significant: (1) The pressure within the reservoir does not begin to rise until the summit of the aortic pressure wave is reached; thereafter it rises and falls as a sine wave, i.e., does not reduplicate the contour of the aortic pulse. (2) As pressure rises in the reservoir it terminates the elevation of aortic pressure, causes a rapid decline and a low incisural pressure, followed by development of a definite wave or an accentuation of a previously existing one. The femoral pulse in addition to a smaller amplitude develops a marked dicrotic notch followed by a great intensification of the dicrotic wave. These results were precisely the opposite of effects anticipated from augmentation of distensibility. (3) Measurements revealed no discernible delay in pulse transmission or change in the period of the dicrotic waves such as were anticipated from a marked increase in distensibility of the aortic system. The following conclusions appear warranted: (1) The insertion of a compression chamber into the aorta does not produce a common system, but two systems with independent natural frequencies. (2) Such a chamber affects pressures in the arterial system by abstraction of blood during the latter portion of systole. This abstraction initiates a negative pressure wave and, through reverberation, a positive pressure wave which are superimposed on the aortic and femoral pulses. The natural frequency of the arterial system remains virtually unchanged. (3) The reduction in pulse amplitude is not due to damping but to an effect of increasing the capacity of the whole arterial system. It remains to be demonstrated whether or not natural saccular aneurysms of the aorta produce similar dynamic effects.

This publication has 4 references indexed in Scilit: