Intraoperative assessment of renal and visceral artery reconstruction: the role of duplex scanning and spectral analysis.

ABSTRACT

To refine our ability to assess intraoperatively renal and visceral reconstructions, we have investigated the usefulness of combined duplex scanning and Doppler spectral analysis to determine the technical adequacy and flow characteristics of these repairs. We studied 62 patients (116 arteries) who underwent renal (83 arteries) or visceral (13) reconstruction by transaortic endarterectomy (76), autogenous graft (12) or prosthetic (5) bypass, reimplantation (2), and dilation (1). Twenty-six nonreconstructed vessels were also studied, including preoperative arteries (6), unrepaired arteries (14), and normal renal arteries (donor nephrectomies) (6). Duplex scanning was performed by means of a 7.5 or 10 MHz probe placed in a sterile glove and plastic sleeve. Peak (Vs) and mean (Vm) velocities measured in meters per second were subsequently calculated from frequency spectral analysis. Spectral broadening (SB) and aortic inflow data were also collected and analyzed. There were no complications related to ultrasound scanning. Mean scan time was 7.8 minutes. Fourteen of 26 nonreconstructed vessels (54%) appeared normal by duplex scanning, including all six control (normal) renal arteries. Sixty-five reconstructed arteries (68%) appeared normal, 27 had various minor defects, and four had major defects (three occlusions and one floating thrombus). The major defects were repaired, whereas minor ones were not. Confirmatory studies were obtained in 19 (73%) nonoperated and 73 (76%) operated vessels. There were two false negative duplex studies (sensitivity 89%) and 17 false positive duplex studies--all minor defects (specificity 77%). The predictive value of duplex scans in detecting the presence of confirmed defects was Tau = 0.47 (p = 0.01). Although SB correlated with B-mode imaging alone (Tau = 0.21, p = 0.07), it added no independent value in predicting the results of a confirmatory study. No other variable (Vs, Vm, or aortic inflow) added to the duplex scan in predicting an abnormal confirmatory study. Detailed renal and visceral artery spectral analysis data are provided for validation of this technique and comparison with transcutaneous studies. These data suggest that the requirement for reliable and immediate assessment of renal and visceral reconstructions, particularly those involving transaortic extraction endarterectomy, is satisfied by duplex scanning.