Pressure Wave Transmission along the Human Aorta

Abstract

Pressure waves were recorded in the proximal aorta, iliac artery, and intermediate sites in 39 patients, aged 6 to 69 years, during diagnostic catheterization. In children, amplitude of the pressure wave increased progressively along the aorta, and a prominent diastolic wave appeared in the distal aorta and iliac artery. These changes in contour were associated with fluctuations in modulus and phase of the pressure wave harmonics. Alterations in the pressure wave during transmission became progressively less with increasing age, and the wave was transmitted virtually unchanged in the older patients with arterial degenerative disease. Percentage amplification (A) of the wave between aortic arch and iliac artery and age (x) were inversely related (A = 58.9 - 0.90x; P <0.001). Transmission time (T, msec) from diaphragm to iliac artery shortened with age (T = 63.5 - 0.62x; P <0.001) indicating a decrease in arterial distensibility. The relationship between amplification and transmission time in the abdominal aorta and iliac artery was A = 1.04T - 16.7 (P< 0.001). Findings are attributed to a decline in peripheral reflection coefficient resulting from decreased distensibility of peripheral arteries with age and in arterial degenerative disease. The functional effects of decreased distensibility are to impair the efficiency of the arterial system in accepting pulsatile flow, and so to increase the load presented to the left ventricle.