Renovascular Hypertension

Hypertension constitutes a major health problem and the challenge is to identify patients having ‘surgically’ curable renal vascular disease among the majority with so-called essential hypertension. The best of unsatisfactory diagnostic tests are renography and plasma renin activity both before and during angiotensin II blockade. The necessity of better screening tests has increased because of the recent advances in surgical techniques and especially percutaneous transluminal renal angioplasty. The latter has definitely become the method of choice for correction of suspected hemodynamically significant artery stenoses whenever technically feasible. With improved angioplasty techniques the risk of treating renal artery stenosis without hemodynamic and clinical importance (so-called cosmetic repair) has increased. Unfortunately randomized trials including surgery versus angioplasty are not available. It should be kept in mind that only after correction of the stenosis is achieved and the blood pressure has become normal, can the diagnosis of renovascular hypertension be made with certainty.

Common secondary causes of resistant hypertension and rational for treatment

Resistant hypertension is defined as uncontrolled blood pressure despite the use of three antihypertensive drugs, including a diuretic, in optimal doses. Treatment resistance can be attributed to poor adherence to antihypertensive drugs, excessive salt intake, physician inertia, inappropriate or inadequate medication, and secondary hypertension. Drug-induced hypertension, obstructive sleep apnoea, primary aldosteronism, and chronic kidney disease represent the most common secondary causes of resistant hypertension. Several drugs can induce or exacerbate pre-existing hypertension, with non-steroidal anti-inflammatory drugs being the most common due to their wide use. Obstructive sleep apnoea and primary aldosteronism are frequently encountered in patients with resistant hypertension and require expert management. Hypertension is commonly found in patients with chronic kidney disease and is frequently resistant to treatment, while the management of renovascular hypertension remains controversial. A step-by-step approach of patients with resistant hypertension is proposed at the end of this review paper.

Pre- and postoperative studies in 72 hypertensive patients with renal artery stenosis, with special reference to renin activity and aldosterone

Seventy-two patients, aged 6-69 years, were operated on because of presumed renovascular hypertension and subjected to follow-up studies for 4-60 months (mean 28). Unilateral renal artery stenosis was present in 47 patients. Surgery was followed by normalization of blood pressure (BP) in 28 and improvement in 7, whereas 12 showed no response. Sixteen were below the age of 40 and only one failed to respond to surgery. Peripheral venous plasma renin activity (PRA) was increased in 32 and urinary aldosterone elevated in 22 of 35 patients responding favourably to surgery. Renal vein PRA was higher from the kidney with the stenotic renal artery as compared to the contralateral side in all patients responding to surgery. Preoperative peripheral PRA difference was also found in 7 of 12 patients not responding to surgery. Preoperative peripheral PRA was increased in 26 of the patients becoming normotensive after surgery. In 20 of these patients normalization of BP was associated with a fall in peripheral PR. Twenty-five patients had bilateral renal artery stenosis. Four of them had severe hypertension, renal insufficiency and generalized atherosclerosis. They died in immediate connection with operation. Unilateral operation, performed in 11 of the remaining 21 patients, was followed by normalization of BP in 3 and no response in 8. Bilateral reconstructive surgery, performed in 10 patients, resulted in normotension in 2 and improvement in 7. Our studies indicate that determination of peripheral PRA and/or urinary aldosterone can serve as a useful prognostic indicator after surgery in hypertensive patients with renal artery stenosis.

The prevalence of secondary and curable hypertension

The prevalence of secondary and curable hypertension was studied retrospectively in 1000 patients. The concept of "secondary hypertension" was used when hypertension was combined with a disease which may have affected the individual's blood pressure. When this definition was applied, 47 of the patients displayed some form of secondary hypertension: stenosis of the renal artery in 10, renoparenchymal disease in 21, hydronephrosis in 3, and endocrine hypertension in 13 (8 of the latter were using oral contraceptives). The blood pressure normalized in 11 and improved in 7 of these patients after operative treatment of the underlying disease or, when appropriate, discontinuance of intake of contraceptive pills. The incidence of secondary hypertension in this and other series is low, and the number of patients with curable hypertension is even lower. In the majority of cases, secondary hypertension can be diagnosed by anamnesis, physical examination and simple tests of blood and urine. If this basic investigation can be extended, the incidence of stenosis of the renal artery should be examined in the first place. Hypertension in young patient and in patients who are difficult to treat often justifies a more extensive investigation.

Prevalence of primary hyperaldosteronism in resistant hypertension: a retrospective observational study

BACKGROUND

Results of several studies published since 1999 suggest that primary hyperaldosteronism (also known as Conn's syndrome) affects more than 10% of people with hypertension; however, such a high prevalence has also been disputed. Experts generally agree that resistant hypertension has the highest prevalence of primary hyperaldosteronism, on the basis of small studies. We aimed to assess the prevalence of primary hyperaldosteronism in a large group of patients with resistant hypertension.

METHODS

Patients with resistant hypertension (blood pressure >140/90 mm Hg despite a three drug regimen, including a diuretic) who attended our outpatient clinic were assessed for primary hyperaldosteronism. Serum aldosterone and plasma renin activity were determined and their ratio was calculated. Patients with a positive test (ratio >65.16 and aldosterone concentrations >416 pmol/L) underwent salt suppression tests with intravenous saline and fludrocortisone. Diagnosis of primary hyperaldosteronism was further confirmed by the response to treatment with spironolactone.

FINDINGS

Over 20 years, we studied 1616 patients with resistant hypertension. 338 patients (20.9%) had a ratio of more than 65.16 and aldosterone concentrations of more than 416 pmol/L. On the basis of salt suppression tests, 182 (11.3%) patients had primary hyperaldosteronism, and response to spironolactone treatment further confirmed this diagnosis. Hypokalaemia was seen only in 83 patients with primary hyperaldosteronism (45.6%).

INTERPRETATION

Although the prevalence of primary hyperaldosteronism in patients with resistant hypertension was high, it was substantially lower than previously reported. On the basis of this finding, we could assume that the prevalence of primary hyperaldosteronism in the general unselected hypertensive population is much lower than currently reported. Thus, the notion of an epidemic of primary hyperaldosteronism is not supported.

Primary aldosteronism - treatment options

Diagnosis of primary aldosteronism results in either the surgical cure of hypertension or targeted pharmacotherapy. The two major subtypes of primary aldosteronism are unilateral aldosterone-producing adenoma (APA) and bilateral idiopathic hyperaldosteronism (IHA). Patients with APA usually are treated with unilateral adrenalectomy and patients with IHA are treated medically. The majority of patients with primary aldosteronism have the IHA subtype and require pharmacotherapy. Spironolactone has been the drug of choice to treat primary aldosteronism. However, it is not selective for the aldosterone receptor, and side effects include gynecomastia, erectile dysfunction and menstrual irregularity. Eplerenone is a new competitive and selective aldosterone receptor antagonist recently approved by the United States Food and Drug Administration for the treatment of hypertension. It lacks the side effects associated with spironolactone and will be the superior drug if it is shown to be as effective as spironolactone for the treatment of mineralocorticoid-dependent hypertension.

Minireview: primary aldosteronism--changing concepts in diagnosis and treatment

Primary aldosteronism affects 5-13% of patients with hypertension. Patients with hypertension and hypokalemia and most patients with treatment-resistant hypertension should undergo screening for primary aldosteronism with a plasma aldosterone concentration to plasma renin activity ratio. A high plasma aldosterone concentration to plasma renin activity ratio is a positive screening test result, a finding that warrants confirmatory testing. For those patients that want to pursue a surgical cure, the accurate distinction between the subtypes (unilateral vs. bilateral adrenal disease) of primary aldosteronism is a critical step. The subtype evaluation may require one or more tests, the first of which is imaging the adrenal glands with computed tomography, followed by selective use of adrenal venous sampling. Because of the deleterious cardiovascular effects of aldosterone, normalization of circulating aldosterone or aldosterone receptor blockade should be part of the management plan for all patients with primary aldosteronism. Unilateral laparoscopic adrenalectomy is an excellent treatment option for patients with unilateral aldosterone-producing adenoma. Bilateral idiopathic hyperaldosteronism should be treated medically. In addition, aldosterone-producing adenoma patients may be treated medically if the medical treatment includes mineralocorticoid receptor blockade.

Antihypertensive pharmacogenetics: getting the right drug into the right patient

Pharmacogenetic investigation seeks to identify genetic factors that contribute to interpatient and interdrug variation in responses to antihypertensive drug therapy. Classical studies have characterized single gene polymorphisms of drug metabolizing enzymes that are responsible for large interindividual differences in pharmacokinetic responses to several antihypertensive drugs. Progress is being made using candidate gene and genome scanning approaches to identify and characterize many additional genes influencing pharmacodynamic mechanisms that contribute to interindividual differences in responses to antihypertensive drug therapy. Knowledge of polymorphic variation in these genes will help to predict individual patients' blood pressure responses to antihypertensive drug therapy and may also provide new insights into molecular mechanisms responsible for elevation of blood pressure.

Polymorphic ventricular tachycardia due to renal artery stenosis--a case report

Atherosclerotic renal artery disease is common among patients with hypertension over the age 50 years who are resistant to medical treatment. In this case report, the authors present a 55-year-old woman with unilateral renal artery stenosis with a history of cardiac arrest. QT prolongation and evident hypokalemia were the main clinical findings of the patient. The patient also had an episode of polymorphic ventricular tachycardia during hospitalization that degenerated into ventricular fibrillation. After successful balloon dilation of the stenotic renal artery, the patient stayed normotensive and normokalemic without medication, and no arrhythmia was observed during the 6-month follow-up period.

Carbon dioxide digital subtraction angiography for renal artery stent placement

PURPOSE

To determine the efficacy of renal artery stent placement with use of carbon dioxide as the primary contrast agent.

MATERIALS AND METHODS

Seventeen hypertensive patients with renal ostial stenosis were evaluated and underwent stent placement with use of CO2 digital subtraction angiography (DSA). Besides hypertension, 11 patients had decreased renal function, three had iodinated contrast material allergy, one patient had both, and two had neither. Supplemental iodinated contrast material (25 mL or less) was used in five patients. Preprocedure and postprocedure serum creatinine levels were obtained to evaluate the effect of CO2 on renal function. Arteriography was used to evaluate stent positioning.

RESULTS

Twenty-three Palmaz stents were placed in 17 patients. Six placements were bilateral, with a total of nine right and 14 left. No additional stents were required to correct malposition. One patient had a mildly significant, yet transient, rise in the postprocedure creatinine level. This patient received 10 mL of iodinated contrast material in addition to CO2. There were no allergic reactions.

CONCLUSION

The utilization of CO2 DSA facilitates the accurate placement of renal artery stents by eliminating the concern for contrast material-associated nephropathy and allergy. These attributes, coupled with the benefit of low viscosity, permit unrestricted imaging, guidance, and precise positioning not afforded by iodinated contrast material.

Two-way referral bias: evidence from a clinical audit of lymphoma in a teaching hospital

The objective of this study was to evaluate the effect of referral bias in a clinical audit of lymphoma in a university hospital. We compared demographic and clinical characteristics as well as survival for Jerusalem residents (local) and referred (distant) patients diagnosed from 1987 to 1992 and treated in our institution. Referred patients were younger (p < 0.0001), and less likely to be immigrants (p < 0.0001), than local patients. Aggressive non-Hodgkin's lymphomas (NHL) were more common in the referred population (p = 0.015). Survival for Hodgkin's disease was consistently better for local patients, but for patients with NHL the findings were reversed. In this study referred patients differed in their clinical and sociodemographic characteristics but did not consistently exhibit a worse outcome than that of local patients. The unpredictable nature of referral bias may be due to better functional status or resources among referred patients, or to selective referral for procedures such as bone marrow transplantation. While reports on the natural history of disease from tertiary institutions may be biased by referral patterns, the direction of the bias is not uniform.

Nondialysis management of chronic renal failure

Chronic renal failure is a complex syndrome encompassing clinical manifestations from all the organs in the body. The aims of conservative management are to prevent and treat the important clinical manifestations and to prevent the progression of renal failure.

Generalizability of clinical studies conducted at tertiary care medical centers: a population-based analysis

The Marshfield Epidemiologic Study Area (MESA), a geographically defined population registry at one of the participating sites in SUPPORT (a multicenter study of the care of seriously ill hospitalized patients) permitted assessment of generalizability in that study. On the basis of age- and sex-specific rates of enrollment of SUPPORT patients in MESA, we estimate that about 400,000 patients per year would fulfill SUPPORT eligibility criteria in the United States. However, an estimated 925,000 patients, particularly the elderly and those with impairments in their activities of daily living (ADLs), have SUPPORT-like illnesses annually, but do not receive the aggressive care required for study enrollment. The absence of patients not interested in aggressive care in tertiary care-based studies is compounded by the overrepresentation of patients referred from distant areas to the tertiary care center. Such patients tended to be older and to have different diseases than patients in MESA. Care should be taken in generalizing results from clinical and epidemiologic studies conducted at tertiary care centers.

Genetic risk for renal artery stenosis: association with deletion polymorphism in angiotensin 1-converting enzyme gene

Atherosclerotic renal artery disease is an important secondary cause of hypertension. Currently, there is great interest in possible genetic determinants of cardiovascular disease. The ACE-D allele has been reported to be associated with increased risk of myocardial infarction as well as coronary re-stenosis after angioplasty. We therefore assessed whether this allele is also linked to renovascular disease by studying 56 Caucasian subjects with atherosclerotic renal artery stenosis and 74 age, sex and race matched control subjects. Genetic analysis for the ACE I/D polymorphism was performed on peripheral leukocytes using PCR techniques, including insertion-specific primers. The distribution of I and D alleles was: renal artery stenosis 8 II, 25 ID, 23 DD; and controls, 16 II, 41 ID, 17 DD. The frequency of the D allele in the renal artery stenosis group was significantly higher (D/total 71/112 = 0.66) than that of the control population [75/148 = 0.51; chi 2 = 4.17, P = 0.04; odds ratio 1.69 (95% CI 1.02 to 2.78)]. Our results suggest that the ACE-D allele may be associated with increased risk of vascular disease at sites other than the coronary circulation.

Minimally invasive diagnosis of renal artery stenosis by spiral computed tomography angiography

We prospectively compared in a blinded fashion spiral computed tomography angiography (CTA) with arteriography in 62 consecutive patients with suspected renal artery stenosis (RAS). For CTA 150 ml of contrast material were injected intravenously. Arteriography was performed by DSA technique with selective catheterization of renal arteries. Of the 157 visualized renal arteries 155 could be evaluated with DSA and a total of 157 with CTA. Sensitivity of CTA for RAS > or = 50% was 98% and the specificity was 94%. Comparison of the grade of stenosis as evaluated by DSA versus CTA showed: identical gradation in 59 arteries (DSA > or = 50%/CTA > or = 50%), underestimation by CTA in one artery (DSA 50 to 75%/CTA < 50%), and overestimation by CTA in six arteries (DSA < 50%/CTA 50 to 75%). Factors that may contribute to these differences include impaired renal function and possibly "underestimation" of ostial RAS by arteriography. One artery not evaluable by arteriography showed a 70% stenosis by CTA. CTA showed no major side effects. We conclude that CTA has the same accuracy for the diagnosis of RAS > or = 50% as arteriography. However, CTA is only minimally invasive, safe, and causes less discomfort to patients.

Renal artery stenosis: a common and important problem in patients with peripheral vascular disease

OBJECTIVE

To study the prevalence, severity, vascular risk factors, and clinical implications of renal artery stenosis in patients with peripheral vascular disease.

DESIGN

Cross-sectional study of consecutive patients who were electively referred from the department of vascular surgery for lower limb digital subtraction angiography.

SETTING

St. George's Hospital, London, United Kingdom.

SUBJECTS

One hundred twenty-seven patients presenting with intermittent claudication or lower limb ischemic ulceration.

MAIN OUTCOME MEASURES

Prevalence and clinical importance of renal artery stenosis in patients with peripheral vascular disease adjusted for the confounding effects of age and hypertension.

RESULTS

Of the 127 patients, 57 (44.9%) had renal artery disease, of whom 22 (17.3%) had mild disease, 20 (15.7%) had severe disease, and 15 (11.8%) had bilateral renal artery stenosis. There was a significant positive relationship between the presence of renal artery stenosis and the severity of peripheral vascular disease (p = 0.00015). The risk of having renal artery stenosis was nearly four times greater in those with three to four vessels affected and nearly seven times greater in those with five or more vessels affected as compared with those with a milder degree of peripheral vascular disease (one or two vessels affected). This association persisted when the confounding effect of age and hypertension was accounted for. Six patients (31.6%) with renal artery stenosis who underwent revascularization for peripheral vascular disease died during the early postoperative period of cardiac or renal complications. None of the patients with normal renal arteries who had similar surgery developed postoperative complications (p = 0.005).

CONCLUSIONS

Renal artery stenosis is a common independent feature in patients with peripheral vascular disease, and its prevalence increases with the increasing severity of the peripheral vascular disease. The postoperative risk following revascularization for peripheral vascular disease appears to be greater in those patients with renal artery stenosis. All patients studied with digital subtraction angiography for peripheral vascular disease should have an aortic flush performed to image the renal arteries. This information may be used to identify those patients likely to develop postoperative complications during peripheral revascularization.

Radiologic diagnosis of renovascular hypertension and percutaneous transluminal renal angioplasty

Percutaneous transluminal renal angioplasty (PTRA) is a low risk, cost-effective procedure with a high degree of technical and therapeutic success in most categories of renovascular hypertension (RVH) when performed at experienced centers. The role of radiology in screening and diagnosis is discussed with special attention to renal vein sampling for renin assay (RVR) and digital subtraction angiography (DSA). The results of PTRA are compared with surgery. At New York Hospital, PTRA is the procedure of first choice in fibromuscular dysplasia, unilateral nonostial atheroma, arteritis, renal transplantation, and pediatrics. In patients with bilateral and ostial atherosclerotic disease and/or azotemia, the choice between surgery or PTRA depends on the surgical risk category of the patient.

Diagnosis of unilateral renovascular hypertension: comparative effect of intravenous enalaprilat and oral captopril

The effectiveness of 2 angiotensin converting enzyme inhibitors, intravenous enalaprilat and oral captopril, in stimulating renin secretion was compared in 47 hypertensive patients with suspected renovascular hypertension. Both inhibitors were more effective stimuli to renin secretion than head-up tilting of the patient. In patients with unilateral renovascular hypertension single doses of angiotensin converting enzyme inhibitors increased the renal venous renin ratio compared to the recumbent ratio. This therapy reduced the number of false negative studies more effectively than head-up tilting and was tolerated better. Contralateral suppression of renin in the unaffected kidney, an important ancillary diagnostic marker of unilateral renovascular hypertension, was preserved. No false positive studies owing to the use of angiotensin converting enzyme inhibitors acutely were apparent. Mean arterial pressure decreased by 5 minutes with intravenous enalaprilat and by 20 minutes with oral captopril, and it continued to decrease gradually for at least 2 hours. No significant syncopal symptoms were observed with either inhibitor. Plasma renin activity increased by 5 and 15 minutes with enalaprilat and captopril, respectively. Plasma aldosterone levels decreased by 10 minutes with enalaprilat and by 30 minutes with captopril, and these changes increased in magnitude during the 2 hours of observation. To achieve the maximum diagnostic effectiveness from the renal venous renin ratio, single dose angiotensin converting enzyme inhibitors warrant consideration for routine use. Intravenous enalaprilat may be preferable because of certain achievement of an effective blood level.

The renin-angiotensin systems

The renin-angiotensin systems are important regulators of cardiovascular homeostasis and participate in a variety of pathological conditions. Recent advances have not only clarified the functioning of the systemic renin cascade but have also indicated the importance of the generation of angiotensin in tissues.

Essential hypertension: cost-effective evaluation and treatment

The widespread prevalence of hypertension in the United States and the enormous expense and effort associated with its treatment necessitate a cost-conscious approach to evaluation and therapy. In the past, we have devoted too many resources to testing for rare diseases suspected of causing hypertension when it has been demonstrated that secondary causes are rare. Devoting resources to the effective treatment of essential hypertension itself should be a priority, because such treatment has been shown to reduce morbidity and mortality associated with hypertension and related cardiovascular diseases. Clinical and epidemiologic studies have demonstrated that treatment for hypertension should not be initiated unless diastolic blood pressure readings are 90 mm Hg or greater on three successive office visits. Treatment should be carried out in a step-wise fashion, using a non-pharmacologic approach only in situations in which hypertension is mild, target organ disease is absent, and compliance is favorable. Diuretics should be used as step-one drug therapy in most situations, because they are effective in the majority of patients, convenient to use, easy to titrate, and comparatively inexpensive. They do not cause salt and water retention, and side effects are usually minimal. When the use of diuretics is contraindicated, beta blockers are suitable alternatives, equally effective in most respects. When beta blockers or other non-diuretic drugs are used as step-one therapy and an additional drug is needed, diuretics can be used advantageously in conjunction with the step-one drug.

Assessment of medical certificates with a diagnostic outcome method

This study which focused on the 169 approved certificates for patients applying for the right for "free" medication in a sickness insurance district during one year in Finland shows two interesting findings. These, cannot of course be generalized because of the low number of observations and of doctors involved (total of 17, of whom three had written the majority of the certificates): the strict application of the official criteria to the certificates would have caused 93% of them to be turned down as very deficient, i.e. not qualifying for insurance fund coverage of medication costs, compared with the 33% when using the generally accepted and tested valid criteria. The proportion of the false negatives when using the minimum number of the official criteria would have been 89%. However, all the 169 certificates had been accepted by the sickness insurance board on the advice of the physician member of the board; It was also found that the control of the BP after a treatment period of four months or longer before qualifying for "free" medication was far from adequate according to these data. Indeed, the longer the treatment period the worse the level of control. Although this does not tell anything about the level of control after granting the right for "free" medicines, it raises very serious questions and obviously needs a thorough clarification. If this finding were to be generalised which as yet it is not, it would mean that the whole system of free medication for chronic hypertension became questionable and that urgent measures would be needed to correct this weakness. The problem is of considerable importance from the economic point of view.

Renal revascularization in the azotemic hypertensive patient resistant to therapy

We undertook this study to assess the frequency of renovascular hypertension in patients with azotemia and hypertension refractory to drug therapy and to determine the effects of renal revascularization on blood pressure and renal function in these subjects. Thirty-nine of 106 consecutive patients admitted for diagnostic evaluation of severe hypertension proved to have renovascular hypertension. Of 21 hypertensive patients with renal insufficiency, 10 appeared to have renovascular hypertension with either bilateral atherosclerotic renovascular disease or unilateral renal arterial stenosis in a solitary functioning kidney. Medical therapy in the hospital often induced further deterioration of renal function despite enhanced blood-pressure control. However, surgical revascularization or percutaneous transluminal angioplasty produced improvement or stabilization of renal function and control of blood pressure in all patients with azotemia who were treated in this manner, despite longstanding hypertension. The benefits of therapy have persisted for 10 to 42 months of follow-up. These studies indicate that refractory hypertension in association with renal insufficiency is a relatively common clinical presentation for renovascular hypertension and bilateral renal-artery disease. Diagnostic evaluation and consideration of renal revascularization appear warranted in such patients, both for the control of the hypertension and for improvement in renal function.

Role of balloon dilatation in the treatment of renovascular hypertension

Renal angioplasty is now well established as a treatment for renovascular hypertension. In patients with fibromuscular dysplasia, the technique is usually technically successful, and the therapeutic effect on blood pressure is as good as with surgical revascularization. In patients with atheroma, the success rate is lower, mainly because of technical problems associated with inability to pass the catheter across the stenosis. In patients in whom this can be done, the results are similar to those of surgery. In our experience, the rate of restenosis is acceptably low, and in most patients, improvement has been maintained over two years. Selection of suitable patients is based on screening from the clinical history and examination, combined with renin-sodium profiling. Renal vein renin measurements have been found reliably to predict the therapeutic outcome of angioplasty, and the incremental method of Vaughan has been preferable to use of the ratio between the two renal veins. In patients with high renin-sodium profiles or in those with normal profiles and a clinical suspicion of renovascular hypertension, renal vein renin values would be determined next, usually with digital intravenous angioplasty. A single test dose of captopril may also be useful as a screening test. If these procedures do indicate the presence of renovascular hypertension, the patient is admitted to the hospital, and arteriography and angioplasty are performed at the same session.

Effects of percutaneous transluminal angioplasty on renal plasma flow

Percutaneous transluminal angioplasty is being used with increasing frequency for the treatment of renal artery stenosis. Several noninvasive techniques that utilize radioactive tracers have been used for monitoring the effects of angioplasty and progression of disease. Forty-one patients were studied before and after renal angioplasty by using renograms and fractionated measurements of effect renal plasma flow. Although there were striking examples of improvement in effective renal plasma flow following angioplasty, this was not a consistent finding. There was a tendency for effective renal plasma flow to revert to the baseline level on follow-up studies. Cure of hypertension was more likely in patients without renal insufficiency and in patients with shorter periods of sustained hypertension. Fractionated effective renal plasma flow studies did not reliably differentiate patients who were cured from those who were improved nor were we able to delineate clearly those requiring repeat dilatation. Nevertheless, this technique is useful for noninvasively measuring fractionated renal function in the immediate postoperative or postdilatation recovery period and for detecting the difference between occlusion of the renal artery and transient renal insufficiency due to contrast material. Also, long-term measurement of fractionated function has value in following potential progression of the basic disease process.

Percutaneous transluminal angioplasty: experience in balloon dilatation of peripheral coronary and renal arteries

Balloon catheter dilatation (percutaneous transluminal angioplasty) of peripheral, coronary and renal arteries is reported, comprising 80 arteries in 62 patients. The clinical success rate was 79% complete relief of symptoms, 9% partial relief. Recurrence was 7% in a follow-up period of one month to 20 months, mean 6 months. There was a 6% incidence of complications requiring surgery. This and other recent reports indicate that, provided the current high patency rate continues on long-term follow-up, percutaneous angioplasty has a major contribution to make in the management of arterial disease. Advantages include relatively low morbidity and cost, and short rehabilitation time. It can be repeated if necessary, and in the event of failure surgical treatment is seldom precluded. Close co-operation between disciplines is essential for optimum case selection and if complications arise.

Renovascular hypertension in black patients

In a 10-year period, 7200 of 19,000 black hypertensive adults in the University of Cincinnati Medical Center were referred to the Hypertension Service. In selected patients, intravenous urograms (1038) and renal arteriograms (238) were performed; 47 cases of renovascular hypertension (0.65% of the referred group and 0.25% of the entire sample) were identified. Atherosclerosis (32 patients) and fibromuscular dysplasia (11) were the most common causes of renal artery obstruction. Other lesions included traumatic thrombosis (2), Leriche syndrome (1), and postrenal transplant anastomotic thrombosis (1). Twenty-four patients were operated on (6 cured, 14 improved, 4 dead) and 23 treated medically (18 improved, 2 unimproved, 3 dead). Surgical mortality was 0. Follow-up exceeded 5 years in 25 patients. Extrarenal vascular lesions were found in 30 patients and accounted for six of seven deaths. Renal vein renin ratios greater than 1.5:1 (affected to unaffected side) predicted successful surgery in 14 patients, but eight of nine operated patients with ratios less than 1.5:1 also had favorable results. Factors in addition to renin assay were weighed before surgery was recommended. Since renovascular hypertension is rare in adult blacks, intensive investigation for this entity is justified only in patients with distinct suggestive findings. Treatment results in blacks are similar to those in white cohorts.