Effect of downstream cross-sectional area of an arterial bed on the resistive index and the early systolic acceleration

Radiology. 1999 Sep;212(3):732-8. doi: 10.1148/radiology.212.3.r99se13732.


Purpose: To evaluate the effect of the increase in total cross-sectional area of arteries as they branch beyond the main trunks on the resistive index (RI) and early systolic acceleration (ESA).

Materials and methods: An essentially noncompliant in vitro model that used a pulsatile pump, blood-mimicking fluid, and a branching tubing network that could be configured to produce a downstream cross-sectional area one, two, four, or eight times that of the feeding vessel was used to investigate the relationship, if any, between arterial bed cross-sectional area and the RI and ESA.

Results: The mean ESA in the branching network was inversely proportional to cross-sectional area, decreasing by approximately a factor of two for every doubling of the cross-sectional area. The mean RI in the branching network decreased with increasing cross-sectional area, but not as greatly as the ESA did; the mean RI in the bed with eight times the upstream cross-sectional area had an RI that was approximately three-fourths the upstream RI. These relationships are real, as the slopes of the plots (ESA vs cross-sectional area, P = .001; RI vs cross-sectional area, P < .02) are significantly different from zero.

Conclusion: RI and ESA decrease as a result of increasing downstream cross-sectional diameter of the arterial bed.

MeSH terms

  • Arteries / physiology
  • Blood Flow Velocity / physiology*
  • Humans
  • Models, Cardiovascular*
  • Pulsatile Flow / physiology
  • Systole / physiology*
  • Ultrasonography, Doppler*
  • Vascular Resistance / physiology*