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Use of captopril in the diagnostic work-up of renovascular hypertension
F H Derkx1, L H Tan-Tjiong, G J Wenting
1Department of Internal Medicine I, University Hospital Dijkzigt, Erasmus University, Rotterdam, The Netherlands.
Insights
The captopril test accurately identifies renovascular hypertension in severe cases. This diagnostic tool helps select patients for renal angiography, improving hypertension management.
Area of Science:
- Nephrology
- Cardiovascular Medicine
- Diagnostic Imaging
Background:
- Renovascular hypertension is a significant cause of secondary hypertension.
- Accurate diagnosis is crucial for effective management and preventing complications.
- Identifying renal artery stenosis (RAS) is key in patients with resistant hypertension.
Purpose of the Study:
- To evaluate the diagnostic value of the captopril test in identifying renovascular hypertension.
- To assess the predictive value of blood pressure and plasma renin response to captopril.
- To determine the utility of the captopril test in selecting patients for renal angiography.
Main Methods:
- 179 hypertensive patients underwent diagnostic work-up for renovascular hypertension.
- Patients received 50 mg of captopril, with blood pressure and plasma renin measured after 1 hour.
- Renal angiography was performed on all participants.
Main Results:
- The captopril test demonstrated a high predictive value (0.92) for positive cases using a plasma renin concentration > 200 microU/ml.
- The predictive value for a negative test was 0.81.
- Combining blood pressure response with renin levels did not improve predictive values.
Conclusions:
- The captopril test is a valuable tool for diagnosing renovascular hypertension in specialized clinics.
- It effectively aids in selecting patients with severe or resistant hypertension for renal angiography.
- The test's diagnostic accuracy supports its use in identifying renal artery stenosis.
Abstract:
A total of 179 patients were selected for a diagnostic work-up of renovascular hypertension from a consecutive series of hypertensive patients referred to a single outpatient clinic between January 1978 and January 1985. Selection criteria were: (1) diagnostic blood pressure > 120 mmHg in patients of 40 years or younger, irrespective of whether they were on treatment or not, and/or (2) diastolic blood pressure > 100 mmHg despite combination therapy with at least three drugs. All patients underwent renal angiography. The diagnostic value of the responses of blood pressure and plasma renin 1 h after 50 mg captopril was assessed while the patients were untreated for at least 2 weeks. The captopril test had a predictive value of 0.92 using a concentration of enzymatically active renin in plasma > 200 microU/ml as criterion for a positive test. The predictive value of a negative test was 0.81. Predictive values were not improved by combining blood pressure response with renin level after captopril. The prevalence of renal artery stenosis was 50% (unilateral stenosis 34%). In a hypertension clinic where patients with severe or therapy-resistant hypertension and a high prevalence of renal artery stenosis are seen, the captopril test proves to be useful for selecting cases for renal angiography.