FOLLOW-UP EVALUATION AFTER RENAL-ARTERY BYPASS-SURGERY WITH USE OF CARBON-DIOXIDE ARTERIOGRAPHY AND COLOR-FLOW DUPLEX SCANNING

Purpose: Postoperative evaluation of renal artery bypass grafts histor ically has been obtained by contrast renal arteriography before discha rge from the hospital. Recent reports have advocated replacing arterio graphy with abdominal duplex scanning for evaluating and monitoring th e integrity of renal artery bypasses. We propose a combination of thes e two techniques, which provides minimal risk to the patient and renal parenchymal function. Purpose: Between July 1, 1990, and Dec. 31, 199 1, 17 patients (8 men, 9 women) underwent 24 renal artery bypasses for poorly controlled hypertension or deteriorating renal function. In th e immediate postoperative period each patient underwent carbon dioxide (CO2) renal arteriography to detect any technical defects and to defi ne bypass graft anatomy. Subsequently, color-flow duplex scanning of t he renal artery bypass grafts were done at 3-month intervals with the postoperative CO2 arteriogram for baseline comparison. CO2 arteriograp hy clearly defined proximal/distal anastomotic anatomy, bypass conduit integrity, and bypass conduit runoff. Results: Procedural morbidity w as zero because no hematomas developed and serum creatinine remained s table. Duplex scanning for a mean follow-up of 8.3 months revealed ant egrade flow in 23 bypasses with peak systolic velocity of 60 to 100 cm /sec. One bypass graft had a peak systolic velocity greater than 150 c m/sec suggestive of a proximal anastomotic stenosis; however, the pati ent died before a repeat, verifying CO2 arteriogram could be obtained. Recurrent hypertension developed in one patient with velocities less than 100/cm/sec, and repeat CO2 arteriography revealed no evidence of graft or anastomotic stenosis. Conclusion: CO2 arteriography and duple x scanning provide an accurate means of initially evaluating and subse quently monitoring renal artery bypass grafts, with minimal risk of re nal or patient morbidity.