Evaluation of renal allograft function by Doppler spectrum analysis A preliminary study

Abstract

Abstract. A decreased renal function is rather common after renal transplantation. The causes of this decreased function are diverse and difficult to differentiate. Yet, duplex examination, and especially quantitative Doppler spectrum analysis of the blood velocities in the renal artery, may be an effective method for differentiating between some of these causes. Forty-five renal transplant recipients were included in this preliminary study. Doppler spectra were recorded from the renal artery to the allograft. Parameters were derived from every Doppler spectrum in order to characterize each spectrum. Renal allograft function was evaluated on the basis of a number of clinical parameters. A significant correlation was found between the clinical parameters and the Doppler spectrum parameters indicative for changes in the peripheral resistance. Patients with a normal renal allograft function showed Doppler spectra with a high diastolic flow, typical of a vascular bed with a low peripheral resistance. Patients with a decreased renal allograft function caused by a stenosis in the renal artery could be distinguished by a low peak velocity and a low pulsatility index. A decreased allograft function caused by allograft rejection or cyclosporin nephrotoxicity also led to characteristic arterial flow disturbances. In these cases, the peripheral resistance was increased, and this was primarily reflected in a decrease in the diastolic blood velocity. We conclude that quantitative analysis of the blood velocities in the renal artery by Doppler spectrum analysis seems to be a useful, noninvasive diagnostic tool that discriminates between some of the causes of a decreased renal allograft function.