No 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.ADDITIONAL KEY WORDS impedance wave reflection heart work arteriosclerosis blood pressure harmonic analysis windkessel pulse pressure wave velocity • When relating the systolic and diastolic levels of blood pressure recorded in a peripheral artery to corresponding levels in the proximal aorta, it is necessary to consider the alterations in amplitude and contour of From the Departments of Physiology, Radiology, and Pediatrics, The Johns Downloaded from . O.5 SEC . FIGURE 1Pressure waves recorded between the ascending aorta or aortic arch and common iliac artery in three children. Position 1 is the ascending aorta, position 2 the aortic arch, position 3 the descending thoracic aorta at the level of the diaphragmatic dome, position 4 the abdominal aorta at the second lumbar vertebra, and position 5 the distal part of the common iliac artery at the level of the sacroiliac joint. The beginning of each wave corresponds in time with the peak of the R wave in the simultaneously recorded electrocardiogram.Pressure waves recorded between the ascending aorta or aortic arch and common iliac artery of three adult patients with arterial degeneration. Recording positions and timing of tvaces are the same as in Figure 1.