Figure 154

Abnormal Pressure Pulse Contours

Some conditions of the circulation also cause abnormal contours of the pressure pulse wave in addition to altering the pulse pressure. Especially distinctive among these are aortic stenosis, patent ductus arterio-sus, and aortic regurgitation, each of which is shown in Figure 15-4.

In aortic stenosis, the diameter of the aortic valve opening is reduced significantly, and the aortic pressure pulse is decreased significantly because of diminished blood flow outward through the stenotic valve.

In patent ductus arteriosus, one half or more of the blood pumped into the aorta by the left ventricle flows immediately backward through the wide-open ductus into the pulmonary artery and lung blood vessels, thus allowing the diastolic pressure to fall very low before the next heartbeat.

In aortic regurgitation, the aortic valve is absent or will not close completely. Therefore, after each heartbeat, the blood that has just been pumped into the aorta flows immediately backward into the left ventricle. As a result, the aortic pressure can fall all the way to zero between heartbeats. Also, there is no incisura in the aortic pulse contour because there is no aortic valve to close.

Figure 15-5

Progressive stages in transmission of the pressure pulse along the aorta.

Figure 15-5

Progressive stages in transmission of the pressure pulse along the aorta.

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Essentials of Human Physiology

Essentials of Human Physiology

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