Atherosclerotic renal artery stenosis in 2001--are we less confused than before?

Use of Endovascular Stents in Atherosclerotic Renovascular Stenosis: Blood Pressure and Renal Function Changes in Hypertensive Patients

Atherosclerotic renal artery stenosis may result in hypertension and ischemic nephropathy. Renal artery endovascular stenting has emerged as current therapy; however, the percentage of patients who benefit from this procedure is still not well established. The authors studied 116 hypertensive patients with atherosclerotic renovascular stenosis who underwent successful renal artery stenting for the first time. At 1 year, there was a significant overall decrease in blood pressure in the group after stenting; however, there was no change in renal function. Also, no significant change in the number of antihypertensive drugs was noted. Blood pressure improved in 55% of the patients, worsened in 14%, and remained unchanged in 31%. Renal function improved in 16% of the patients, worsened in 30%, and remained stable in 54%. In relation to blood pressure control, patients with resistant or difficult-to-control hypertension showed the most improvement in blood pressure control after stenting.

Validation of a prediction rule for renal artery stenosis

OBJECTIVES

We previously developed a prediction rule to estimate the probability of renal artery stenosis. This rule should be validated before it can be used reliably to select hypertensive patients for renal angiography. We determined the validity of the prediction rule in recent patients and in other settings.

DESIGN

We studied three aspects of validity (agreement between predicted and observed probability of stenosis, discriminative ability, and clinical usefulness) in 180 consecutive patients with drug-resistant hypertension and normal or mildly impaired renal function, who visited six hypertension clinics of academic and community hospitals in the Netherlands. Thirty-five patients (19%) had a significant stenosis.

RESULTS

The clinical characteristics in the rule (age, sex, vascular disease, recent onset of hypertension, smoking, body mass index, abdominal bruit, serum creatinine concentration, and hypercholesterolemia) had similar predictive value in the validation sample and development sample. The predicted probabilities of stenosis agreed well with the observed frequencies (Hosmer-Lemeshow goodness-of-fit test, P = 0.87). The prediction rule discriminated reasonably between patients with and without stenosis in the validation sample with an area under the receiver operating characteristic curve of 0.71. If only patients with predicted probabilities of stenosis of 5% or more were referred for renal angiography, the number of referrals was reduced by 20%, while 9% of patients with a stenosis were missed.

CONCLUSIONS

The prediction rule was valid in more recently treated patients in other settings. If used conservatively, the rule can reliably exclude a small proportion of patients from angiography.

Value of Doppler sonography for predicting clinical outcome after renal artery revascularization in atherosclerotic renal artery stenosis

OBJECTIVE

The purpose of this study was to prospectively evaluate the usefulness of Doppler sonography for predicting blood pressure and renal function improvement after percutaneous renal angioplasty in patients with unilateral atherosclerotic renal artery stenosis.

METHODS

Thirty-six patients with successfully revascularized unilateral atherosclerotic renal artery stenosis were included. Patients were evaluated by Doppler sonography before treatment, with the resistive index (RI) and acceleration being measured in both kidneys. Blood pressure, number of antihypertensive drugs, and serum creatinine concentration were assessed before treatment and thereafter during a 23 +/- 15-month (mean +/- SD) period.

RESULTS

In 20 of the 36 patients (55%), the RI was less than 0.80 before revascularization. After treatment, blood pressure improved in 17 (85%) of those 20 patients and improved in 8 (50%) of 16 patients with an RI of greater than 0.80 (P < .05). Twenty-five patients had renal insufficiency pretreatment, and 11 (44%) had a baseline RI of less than 0.80. Improvement in renal function after angioplasty was shown in 5 (45%) of these 11 patients and in 4 (28.5%) of 14 in the group with high RI (P > .05, not significant). On analysis of acceleration, blood pressure improved in 9 (69%) of 13 patients with acceleration of greater than 3 m/s(2) and in 16 (69.5%) of 23 with acceleration of less than 3 m/s(2) (P > .05). In patients with renal insufficiency, 5 (50%) of 10 cases with normal baseline acceleration and 4 (27%) of 15 with low acceleration showed improvement in renal function (P > .05).

CONCLUSIONS

An elevated RI should not exclude patients from a revascularization procedure because, although renal RI does correlate with blood pressure response to revascularization, it is not a useful parameter in predicting renal function outcome. Acceleration has no prognostic value.

Atherosclerotic renovascular disease in chronic heart failure: should we intervene?

Renal artery stenosis (RAS) is most commonly caused by atherosclerosis, which is also the most common cause of chronic heart failure (CHF). One-third of patients with CHF are reported to have significant renovascular disease. The presence of RAS confers a worse outcome in studies of hypertension and coronary disease, though data are lacking for patients with CHF. As the kidney is intricately involved in the fluid retention that occurs in CHF, an adverse effect of RAS on outcome would be expected. Presentations of RAS in CHF include flash pulmonary oedema, hypertension, worsening of CHF, and worsening renal function. RAS commonly progresses and may cause worsening of renal function in patients with CHF and previously stable renal function. A variety of investigations that can safely and accurately identify RAS in CHF are available, although none is recommended in current guidelines for the management of CHF. Treatment for RAS, whether for hypertension, for renal dysfunction, or for pulmonary oedema, is at the discretion of the physician due to the lack of adequate randomized controlled trials demonstrating the efficacy and safety of intervention. As it is not clear how RAS should be managed in CHF, screening cannot be advocated. Currently, a multicentre randomized outcome trial, which includes a cohort of patients with RAS and CHF, is in progress to provide answers in this area of uncertainty.

Renal artery stenosis of solitary kidney: the dilemma

BACKGROUND

Renal artery stenosis is an important cause of hypertension and renal failure. When present in a solitary kidney, it is associated with extremely high morbidity and mortality. Although guidelines suggest an aggressive approach by revascularization in these cases, available evidence is too weak and contradictory to provide definite recommendations for treatment.

OBJECTIVES

To discuss the various clinical factors predicting the benefit from revascularization.

METHODS AND RESULTS

Review of more recent clinical trials is presented.

DISCUSSION

The approach to the patient with single kidney and renal artery stenosis is discussed and, although there is insufficient evidence-based medicine for guidelines, some suggestions are made to predict revascularization results in these cases.

CONCLUSION

Continuous development of clinical prediction rules will help in the management of renal artery stenosis of solitary kidney.

Contrast media nephropathy: intravenous CT angiography versus intraarterial digital subtraction angiography in renal artery stenosis: a prospective randomized trial

BACKGROUND

Spiral computed tomographic angiography (CTA) is a noninvasive method to diagnose renal artery stenosis (RAS). In digital subtraction angiography (DSA), contrast media (CM) is injected directly into the renal artery; in CTA, a greater amount of CM is injected intravenously, potentially leading to an increased incidence of CM nephropathy.

METHODS

We investigated 80 patients with suspected RAS randomized to either CTA or DSA prospectively. The following parameters were determined: serum creatinine level and single-shot inulin clearance for evaluation of renal function and urine alpha1-microglobulin and beta-N-acetyl-glucoseaminidase (beta-NAG) as markers for tubular toxicity. Data from 16 patients undergoing angioplasty in the same session were excluded.

RESULTS

In the CTA and DSA groups, 163 +/- 13 and 104 +/- 56 mL of CM (mean +/- SD; P < 0.0001) were administered, respectively. Mean serum creatinine levels increased from 1.78 +/- 1.61 to 1.92 +/-1.73 mg/dL (157 +/- 142 to 170 +/- 153 micromol/L; P = 0.00001) in the CTA group and from 1.52 +/- 1.23 to 1.60 +/- 1.28 mg/dL (134 +/- 109 to 141 +/- 113 micromol/L; P = 0.01) in the DSA group. Mean inulin clearance decreased from 63 +/- 28 to 58 +/- 23 mL/min (P = 0.01) and 65 +/- 26 to 62 +/- 26 mL/min (P < 0.01), median beta-NAG levels increased from 4.6 to 6.0 U/g creatinine (P = not significant) and 2.5 to 8.0 U/g creatinine (P < 0.001), and median alpha1-microglobulin levels increased from 13 to 17 microg/g creatinine (P < 0.025) and 11 to 21 microg/g creatinine (P = not significant) in the CTA and DSA groups, respectively. CM nephropathy occurred in 3 of 33 patients in the CTA group and 2 of 31 patients in the DSA group. The increase in creatinine level was reversible in all patients within 7 days.

CONCLUSION

On this study, CTA performed for the detection of RAS is not associated with an increased risk for CM nephropathy compared with intraarterial DSA despite a greater dose of CM.