Abstract
Changes in the shape of pressure wave traveling along the aorta are caused variously by reflection from the periphery, attenuation, and the elastic non-linearity of the vessel walls. The effect of nitroglycerin (NTG) on the waveform along the aorta was studied in 23 patients (16 males, 7 females, mean age 53 years) following a dose of 3μg/kg/min NTG given intravenously. NTG infusion reduced the late systolic peak in the pressure waves and increased the similarity of the contour between the proximal and distal pressure waves. The ratio of the distal to the proximal pulse amplitude was reduced. The steepening of ascending limb of the pressure wave along the aorta was also reduced. The compliance of the artery increased. Following NTG infusion, the vascular impedance moduli of the upper thoracic aorta decreased for harmonics 1, and 2, and increased for harmonic 6. The velocity of the pulse wave along the aorta did not change significantly. These observations give us the following suggestions : 1) the reflection from the periphery, 2) the non-linearity of the vessel walls were decreased by NTG infusion.
