Computer simulations in comparison with in vivo measurements of nifedipine-induced changes in renal allograft hemodynamics

Merkus, J.W.; van Asten, W.N.; Hilbrands, L.B.; Hoitsma, A.J.; Koene, R.A.; Skotnicki, S.H.

Journal of Ultrasound in Medicine Official Journal of the American Institute of Ultrasound in Medicine 12(9): 517-523

1993


ISSN/ISBN: 0278-4297
PMID: 8107182
DOI: 10.7863/jum.1993.12.9.517
Accession: 045611896

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Abstract
Analysis of Doppler spectrum waveforms is increasingly used in the differential diagnosis of human renal allograft dysfunction. The physiologic interpretation of changes in Doppler spectra obtained from renal allografts, however, remains a major problem. Computer simulation models of the renal circulation may provide insight into the physiologic mechanisms responsible for changes in Doppler spectrum characteristics. The results of measurements of renal allograft hemodynamics with both determinations of PAH clearance and Doppler spectrum analysis in 11 kidney allograft recipients were explained physiologically using a computer simulation model of kidney allograft hemodynamics. Using PAH clearance and blood pressure measurements a significant decrease in RVR was found (from 0.32 +/- 0.17 to 0.20 +/- 0.07 mm Hg x min/ml, P < 0.05) after administration of the vasodilatory drug nifedipine. The Doppler spectrum waveform obtained from interlobar renal arteries showed a decrease in the RI (from 0.60 +/- 0.04 to 0.56 +/- 0.06; P < 0.05) and Tmax (from 133 +/- 32 to 98 +/- 32 ms; P < 0.05). The user-designed simulation model of renal hemodynamics showed comparable changes of the waveform when, in the model, the analogs of blood pressure, impedance of the artery, and the impedance of the peripheral vascular bed were altered proportionally.