Renovascular hypertension

Comparison of diagnostic accuracy of Doppler USG and contrast-enhanced magnetic resonance angiography and selective renal arteriography in patients with atherosclerotic renal artery stenosis

Background

There are many systemic complications of conventional selective renal arteriography (SRA), such as contrast-mediated nephropathy. Contrast-enhanced magnetic resonance angiography (CE-MRA) and renal artery Doppler ultrasonography (DUSG) have been used increasingly for renal artery stenosis (RAS). The aim of this study was to evaluate the accuracy of CE-MRA and DUSG as used for diagnosis of RAS.

Material/Methods

We divided 130 consecutive patients investigated for resistant hypertension into 2 groups based on age: group 1 was patients <60 years old and group 2 was patients >60 year. DUSG, CE-MRA, and SRA were performed in group 1 and group 2 patients.

Results

Seventy-two patients (24 males [M], 48 females [F]) in group 1, and 58 patients (26 M, 32 F) in group 2 were included in the study. In the evaluation of clinically significant renal artery stenosis with DUSG, in group 1 the overall sensitivity was 83.33% and overall specificity was 81.82%, and in group 2 they were 69.23% and 0%, respectively, when compared with SRA. In the evaluation of clinically significant renal artery stenosis with CE-MRA, the overall sensitivity and specificity were 92.31% and 36.36%, respectively, in group 1 and 100.00% and 73.33%, respectively in group 2, when compared with SRA.

Conclusions

CE-MRA is an accurate, non-invasive method for the diagnosis of RAS in patients above 60 years of age and DUSG may be the choice of diagnostic method for RAS in patients under 60 years of age.

Revascularization of the solitary kidney: a challenging problem in a high risk population

BACKGROUND

Patients with significant atherosclerotic stenosis involving the artery to a solitary functioning kidney present a clinical challenge.

METHODS

From August 1987 through August 1995, 35 of these patients (average age, 68.4 +/- 6.9 years) were treated. Comorbid conditions included previous myocardial infarction in 23% of the patients, congestive heart failure (CHF) in 34%, chronic obstructive pulmonary disease in 20%, and diabetes in 20%. The average creatinine level of the patients was 2.5 +/- 1.5 mg/dl. Indications for revascularization were hypertension in 86%, hypertensive crisis with CHF in 17%, and renal insufficiency in 69%. Procedures performed included 19 extra-anatomic bypasses, 8 concomitant with infrarenal aortic reconstruction and 2 concomitant with thoracoabdominal aortic aneurysm repair; 1 visceral segment endarterectomy; 1 renal artery endarterectomy with reimplantation; I superior mesenteric to renal artery bypass; 1 aortorenal bypass; and 2 percutaneous angioplasties with staged nephrectomies.

RESULTS

At discharge, 91% of patients had stable or improved renal function with an average creatinine level of 1.7 +/- 0.8 mg/dl. Hypertension was cured or improved in 85%. Perioperative mortality was 6%, and major morbidity was 43%, including the need for permanent (9%) and temporary (9%) dialysis, respiratory insufficiency (18%), two early reoperations, six cardiac complications, one case of gastrointestinal bleeding, and one stroke. In the follow-up period (mean duration, 39.2 months), survival has been 73%, and no additional patients have required dialysis.

CONCLUSIONS

Although significant perioperative morbidity exists in this high risk population, the long-term preservation of renal function and improvement in hypertension make solitary renal revascularization worthwhile.

Renovascular hypertension. Difficulties in diagnosis and treatment

Renovascular hypertension is not easily identified clinically, and most tests are not totally reliable in detecting its presence. The condition may be due to fibromuscular dysplasia or congenital anomalies in patients younger than age 30 or to atherosclerosis in patients older than 50. The goal of treatment is to lower blood pressure and improve or maintain renal function. Cure or improvement of hypertension is more likely in patients with fibromuscular dysplasia than in those with atherosclerosis. Interventional procedures include percutaneous transluminal angioplasty, surgical revascularization, and nephrectomy.

Retrieval of renal function by revascularization. Study of preoperative outcome predictors

Results of renal revascularization for retrieval of function in poorly functioning kidneys are variable, but criteria for prediction of benefit and patient selection for operation are ill-defined. This report examines preoperative parameters in 64 hypertensive patients who underwent successful revascularization of poorly functioning kidneys as defined by creatinine clearance less than or equal to 15 ml/min (measured by preoperative split renal function studies [SRFS]) or preoperative serum creatinine greater than or equal to 3.5 mg/dl (range: up to 8.9 mg/dl) to identify markers of value in prediction of a beneficial response in renal function. Ages ranged from 35 to 75 years. There were 35 men and 29 women. The renovascular lesion was atherosclerotic in 58 patients and fibrodysplastic in six. Total renal artery occlusion was present in 32 cases. No urine flow was detectable before surgery on SRFS from 13 kidneys. Kidney lengths ranged from 7.7 cm to 15.1 cm. Fifty-four unilateral and 10 bilateral revascularizations were performed. A beneficial blood pressure response to operation was observed in 94%. Benefit in excretory function was determined by comparison of preoperative and postoperative data which included SRFS parameters, renal length, serum creatinine, isotopically derived split functioning renal mass, and glomerular filtration rates. Overall, 56 patients could be classified in regard to functional response. Twenty-two patients received no or minimal benefit; nine patients received modest improvement, and 25 patients exhibited more marked improvement. Statistical evaluation of preoperative anatomic and functional parameters as predictors of functional response suggested that multiple variables influence the probability of function retrieval by revascularization. Useful among these predictive variables are the status of the distal vessel beyond the occlusion, the bilaterality of reconstructable disease in azotemic patients, the amount of residual renal mass available for revascularization, and the degree of hyperconcentration of nonreabsorbable solutes from the involved kidney after surgery.