Captopril-induced changes in effective renal plasma flow in hypertensive renal transplant recipients

The role of converting enzyme inhibitor enhanced radionuclide investigations in post-transplant hypertension is not clearly defined. Presence of renal failure, chronic rejection and use of cyclosporin A complicates the results. Captopril-induced changes in effective renal plasma flow (ERPF) were studied in 10 patients with severe post-transplant hypertension and no evidence of rejection. Angiographic correlation was available in all. Six patients had a significant increase in ERPF after captopril, and all had a negative angiogram. One patient on CsA with a negative angiogram had no change in ERPF. Three patients had a fall in ERPF, and all 3 had transplant renal artery stenosis. Captopril-induced changes in ERPF can differentiate patients with native-kidney-induced hypertension from those with hypertension secondary to transplant renal artery stenosis in patients without evidence of rejection.