IN VIVO ESTIMATION OF ELASTIC CHARACTERISTICS OF THE ARTERIES IN THE LOWER EXTREMITIES OF MAN

Abstract

Arterial distensibility can be studied in intact man by measuring the pulse wave velocity. Since distensibility is known to vary with pressure, in the present study pulse wave velocity was measured over a range of transmural pressures. This was achieved by applying positive or negative pressures to the outside of the extremity while the velocity was measured between the groin and the foot, using intra-arterial needles. Twenty-seven subjects were studied. Distensibility, when plotted against transmural diastolic pressure on logarithmic coordinates, declined linearly with increasing pressure up to at least 70 mm Hg. Above 100 mm Hg there was less change or no further consistent change in distensibility. The slopes, which represent logarithmic relationship between distensibility and pressure in the pressure range up to 70 mm Hg, have been used as an index of the elastic characteristics of the arteries. Body heating or cooling, intravenous norepinephrine or Arfonad had little or no effect on these slopes, which suggests that they are relatively independent of the physiologic state of the subject. The finding that the slopes decreased with increasing age indicates that this method may prove useful in the study of normal and abnormal states of the arteries.