The safe introduction of angiotensin-converting enzyme inhibitor in renal allograft recipients

Antihypertensive and renoprotective treatment with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker is indicated in almost all chronic renal failure patients. However, this treatment is not widely used for renal allograft recipients mainly because of the potential side effects, including a decrease in renal function as well as onset of hyperkalemia or anemia. Herein we investigated the effects of ACEI introduction to hypertensive renal transplantation patients who did not display renal artery stenosis. At least 2 months after transplantation, we exchanged amlodipine (5 mg) for either ramipril or perindopril (5 mg) in 25 patients who were free of renal artery stenosis as determined indirectly by measuring the renal arterial resistance index with the noninvasive, inexpensive Doppler ultrasound method. The resistance index was evaluated again at 2 weeks. Systolic and diastolic blood pressure, serum creatinine, calculated creatinine clearance, serum potassium, hemoglobin and hematocrit were also measured before as well as at 2, 4, and 12 weeks after conversion to ACEI. The conversion did not change the mean renal arterial resistance index, nor did it influence renal function or blood count, and it was equally effective for controlling blood pressure. The serum potassium level increased at 2 and 4 weeks; however, it was within the normal range in all patients. Our data suggested that measurement of the renal arterial resistance index is a noninvasive, inexpensive, and reliable preselection method before introduction of ACEI in renal allograft recipients.