SURGERY AND PERCUTANEOUS ANGIOPLASTY IN THE MANAGEMENT OF RENOVASCULAR HYPERTENSION

Limitations of angiography for the assessment of renal artery stenosis and treatment implications

Renovascular hypertension due to atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Percutaneous catheter-based renal artery revascularization has been increasingly utilized for the treatment of renal artery stenosis. Renal artery stenting has a high technical success rate, but the rate of improvement in hypertension is somewhat less than expected with this technique. Misinterpretation of angiographic images may play a role in these unfavorable clinical results. We present a case in which the diagnosis of severe renal artery stenosis was not apparent by angiography. Intravascular ultrasound and translesional pressure gradient measurements during arteriography can help to determine the precise severity of stenosis and may augment the clinical results of percutaneous renal artery stent placement.

Diagnosis and management of atherosclerotic renal artery stenosis: improving patient selection and outcomes

Renal artery stenosis (RAS) is common among patients with atherosclerosis, and is found in 20-30% of individuals who undergo diagnostic cardiac catheterization. Renal artery duplex ultrasonography is the diagnostic procedure of choice for screening outpatients for RAS. Percutaneous renal artery stent placement is the preferred method of revascularization for hemodynamically significant RAS, and is favored over balloon angioplasty alone. Stent placement carries a class I recommendation for atherosclerotic RAS according to ACC and AHA guidelines. Discordance exists between the very high (>95%) procedural success rate and the moderate (60-70%) clinical response rate after renal stent placement, which is likely to be a result of poor selection of patients, inadequate angiographic assessment of lesion severity, and the presence of renal parencyhmal disease. Physiologic lesion assessment using translesional pressure gradients, and measurements of biomarkers (e.g. brain natriuretic peptide), or both, could enhance the selection of patients and improve clinical response rates. Long-term patency rates for renal stenting are excellent, with 5-year secondary patency rates greater than 90%. This Review will outline the clinical problem of atherosclerotic RAS and its diagnosis, and will critically assess treatment options and strategies to improve patients' outcomes.

Challenges in the diagnosis and management of renal artery stenosis

Renal artery stenosis (RAS) is a common cause of secondary hypertension, with the activation of the renin-angiotensin-aldosterone system being the pathophysiologic hallmark of the disease. Renovascular hypertension, ischemic nephropathy, proteinuria, and flash pulmonary edema are the main clinical syndromes associated with RAS. The prevalence of RAS is on the rise, owing to an increasing prevalence of diabetes and atherosclerotic disease among our aging population. This rise in RAS prevalence poses major challenges for clinicians making diagnostic and treatment decisions. Although renal angioplasty is of proven benefit in fibromuscular dysplasia, randomized trials in atherosclerotic RAS have not shown any advantage for revascularization over medical therapy in terms of blood pressure control or renal function preservation. Angioplasty and surgical interventions should be reserved for patients with preserved kidney size and hemodynamically significant stenosis.

Laparoscopy-Assisted Autotransplantation in Child with Renovascular Hypertension

A 7-year-old boy with hypertension secondary to intimal hyperplasia of the left renal artery was normotensive after laparoscopic autotransplantation following failed angioplasty. This appears to be the first such case reported.

Long-term outcome after surgical kidney revascularization for fibromuscular dysplasia and atherosclerotic renal artery stenosis

PURPOSE

At a time of minimally invasive surgery in urology, the role of surgical kidney revascularization in the management of renal artery disease has changed during the last decade. Our experience with surgical kidney revascularization, and the long-term clinical outcomes of fibromuscular dysplasia (FMD) and atherosclerotic renal artery stenosis are reviewed.

MATERIALS AND METHODS

The study group comprised 140 patients with renovascular hypertension, 72 with FMD and 68 with atherosclerotic renal artery disease, who underwent surgical revascularization between 1982 and 1999. The indications for surgical revascularization were the treatment of hypertension and the preservation of renal function in 17 patients with renal artery occlusion, 55 with ostial stenosis, 52 with branch stenosis, 6 with bilateral artery stenosis, 7 with solitary kidney renal artery stenosis and 3 with solitary kidney renal artery occlusion.

RESULTS

Postoperative blood pressure and renal function were monitored for 1 to 17 years (mean 11.3). Long-term blood pressure control was observed in 93% of patients with FMD and in 71% of those with atherosclerosis. Improvement or stabilization of renal function was observed in 92% of patients with FMD and in 68% of those with atherosclerosis. The preoperative estimated glomerular filtration rate compared to postoperative was significantly increased in both groups.

CONCLUSIONS

Surgical kidney revascularization is effective in secondary hypertension with a high long-term efficacy in the normalization of blood pressure and in the preservation of renal function, especially in patients with a solitary or 1 functional kidney.

The diagnosis and management of renovascular disease: a primary care perspective. Part II. Issues in management

Renovascular disease is a complex disorder, most commonly caused by fibromuscular dysplasia and atherosclerotic disease. It usually presents in one of three forms: asymptomatic renal artery stenosis, renovascular hypertension, or ischemic nephropathy. This complexity may make diagnostic and management decisions difficult for the primary care physician. In Part I of this review (presented in the May/June 2003 issue of The JCH), the authors discussed when to consider and how to go about making a diagnosis of renovascular disease. In Part II, the authors review the management of this complex condition. There is a debate concerning the optimal treatment of patients with renovascular disease. Management options include medical, surgical, or percutaneous approaches (angioplasty and stenting). Generally in patients with fibromuscular disease, the results of surgery and percutaneous approaches appear superior. In patients with atherosclerotic disease, the data are less consistent, and there does appear to be a group of patients who will respond well to medical management. A potential management algorithm is presented.

Type B aortic dissection complicating renal artery angioplasty and stent placement

Percutaneous renal artery stent placement has been demonstrated to improve blood pressure control and stabilize renal function in patients with atherosclerotic renal artery disease. However, this procedure is not without risk of significant morbidity, and its effectiveness, as compared to alternative treatments, has not been adequately established. The authors report a case of acute type B aortic dissection complicating renal artery stent placement. The authors postulate that an intimal disruption occurred during initial balloon angioplasty, and that repeated application of radial, shear, and torque forces during stent placement may have extended the injury. The diagnosis of acute aortic dissection should be considered in patients with suggestive symptoms immediately after stent placement.

Bilateral renal infarction in a black man with medial fibromuscular dysplasia

We report a case of bilateral renal infarction in a patient with medial fibrous dysplasia of both renal arteries and a thrombosed aneurysmal dilatation of the right renal artery. A previously healthy 40-year-old black man presented to the emergency department with acute onset of bilateral flank pain. Computerized tomography of the abdomen showed bilateral renal infarction, predominantly affecting the anterior distribution of both renal arteries. Estimated loss of renal mass was 50% on the right and 25% on the left. The patient was treated with intravenous heparin, oral warfarin, and antihypertensive therapy with labetolol and long-acting nifedipine. By day 3, his abdominal pain resolved; however, the serum creatinine level increased to a maximum value of 2.6 mg/dL. The serum creatinine level slowly improved and stabilized at 1.9 mg/dL, and he was subsequently discharged on the seventh hospital day. Magnetic resonance angiography performed 2 months later showed "beading2 of both renal arteries consistent with medial fibromuscular dysplasia, a finding confirmed by conventional angiography. To our knowledge, bilateral renal infarction complicating medial fibrous dysplasia of the renal arteries has not been previously reported, nor has medial fibrous dysplasia been reported in blacks.

Renal artery repair: consequence of operative failures

OBJECTIVE

This report examines the blood pressure and renal function response in 20 consecutive patients after secondary renal revascularization following failed operative repair.

SUMMARY BACKGROUND DATA

Most reports describing operative failure of renal artery (RA) repair emphasize the technical aspects of redo RA reconstruction and the immediate blood-pressure response to secondary operation. This report examines the eventual renal function and estimated survival after secondary intervention.

METHODS

Primary methods of RA reconstruction, primary blood pressure and renal function responses, and causes of failed RA repair were defined for 20 patients requiring reoperation for recurrent hypertension or renal insufficiency. These parameters were compared with secondary procedures and eventual blood pressure and renal function response. The eventual outcome for these 20 patients was compared with 514 patients managed by primary renal revascularization during the same period.

RESULTS

Failure of primary RA repair correlated with complex fibromuscular dysplasia requiring branch ex vivo reconstruction (p = 0.020). RA thrombosis frequently required nephrectomy (83%), whereas RA stenosis was successfully reconstructed (91 %; p = 0.001). Primary and secondary blood-pressure responses were equivalent (94% vs. 95% cured or improved); however, primary and eventual renal function responses differed significantly (p = 0.015), with seven patients dialysis-dependent on follow-up. Eventual dialysis dependence was associated with preoperative azotemia (p = 0.022), bilateral failure of primary RA repair (p = 0.007), and an increased risk of follow-up death (p = 0.002). Considering all 534 patients, failed RA repair demonstrated a significant and independent association with eventual dialysis dependence and decreased dialysis-free survival.

CONCLUSIONS

Contemporary rates of reoperation after surgical RA repair are low. In properly selected patients, beneficial blood-pressure response is reliably observed after both primary and secondary operative procedures. However, secondary procedures are associated with a significant and independent risk of eventual dialysis dependence.

Percutaneous transluminal angioplasty in the treatment of renovascular hypertension: sequential prospective study

OBJECTIVE

To evaluate the use of percutaneous transluminal renal angioplasty (PTRA) in the treatment of renal vascular hypertension.

DESIGN

Sequential prospective PTRA treatment of severe arterial hypertension, screening by the captopril test, confirmed by renal arteriography, and the result evaluated by post-PTRA arteriography, blood pressure measurement and renal function. SITE: Vascular Surgery, angioradiology sector, and Nephrology outpatients department of the Federal University of São Paulo-Paulista School of Medicine, São Paulo, Brazil, a tertiary health-care institution.

PARTICIPANTS

PTRA was employed on 32 patients screened by clinical examination, captopril test and renal arteriography.

EVALUATION

PTRA results were evaluated by the criteria of the Cooperative Study of Renovascular Hypertension.

RESULTS

After PTRA the completion arteriography showed no renal stenosis in 24 patients (75%), residual stenosis (20-50%) in 3 (9.4%) and no change in 5 (15.6%). The blood pressure results were: 3 patients (9.4%) were cured, 24 (75%) improved and 5 (15.6%) were unchanged. We observed normal renal function before and after PTRA in 25 patients (78%); altered pre- and improved post-PTRA in 2 (6.3%); post-PTRA remained unaltered in 2 (6.3%); and altered pre- and worsened post-PTRA in 3 (9.4%). Recurrence of stenosis occurred in one patient after 8 months.

CONCLUSIONS

PTRA is a convenient procedure, relatively safe and an effective complementary method of medical therapy for controlling renovascular hypertension.

Renal artery stent placement: utility in lesions difficult to treat with balloon angioplasty

OBJECTIVES

We assessed the safety and efficacy of stent placement in patients with poorly controlled hypertension and renal artery stenoses, which are difficult to treat with balloon angioplasty alone.

BACKGROUND

Preliminary experience with stent placement suggests improved results over balloon angioplasty alone in patients with atherosclerotic renal artery stenosis.

METHODS

Balloon-expandable stents were placed in 100 consecutive patients (133 renal arteries) with hypertension and renal artery stenosis. Sixty-seven of the patients had unilateral renal artery stenosis treated and 33 had bilateral renal artery stenoses treated with stents placed in both renal arteries.

RESULTS

Angiographic success, as determined by quantitative angiography, was obtained in 132 (99%) of 133 lesions. Early clinical success was achieved in 76% of the patients. Six months after stent placement, the systolic blood pressure was reduced from 173 +/- 25 to 147 +/- 23 mm Hg (p < 0.001); the diastolic pressure from 88 +/- 17 to 76 +/- 12 mm Hg (p < 0.001); and the mean number of antihypertensive medications per patient from 2.6 +/- 1 to 2.0 +/- 0.9 (p < 0.001). Angiographic follow-up at a mean of 8.7 +/- 5.0 months in 67 patients revealed restenosis (>50% diameter narrowing) in 15 (19%) of 80 stented vessels.

CONCLUSIONS

Renal artery stenting is an effective treatment for renovascular hypertension, with a low angiographic restenosis rate. Stent placement appears to be a very attractive therapy in patients with lesions difficult to treat with balloon angioplasty such as renal aorto-ostial lesions and restenotic lesions, as well as after a suboptimal balloon angioplasty result.

Secondary hypertension: evaluation and treatment

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.