Abdominal bruits in renovascular hypertension

Computer-aided auscultation to diagnose Renal Artery Stenosis

Renal Artery Stenosis (RAS) is the most common cause of secondary hypertension, and early diagnosis is important since correct and timely treatment may cure hypertension and prevent loss of renal function. This study investigates a new approach to diagnosing renal artery stenosis by computer analysis of the phonogram recorded with an electronic stethoscope. Phonograms recorded from five positions over the renal arteries were obtained, three from patients with confirmed RAS and 15 from healthy subjects. Two features describing the power ratios between the systolic and diastolic periods in two different frequency bands were extracted. It was possible to discriminate all three RAS subjects from the healthy subjects in the frequency band 0.4-1.1 kHz. However, the number of subjects is insufficient to draw statistically significant conclusions about the performance of the system.

Endocrine causes of hypertension in pregnancy--when to start looking for zebras

Hypertension is a common medical disorder in pregnancy that may predate or first appear in pregnancy. Endocrine disorders rarely are the cause of the elevated blood pressure. However, it is essential to have a high index of suspicion because they carry much higher fetal and maternal morbidity and mortality risks. Endocrine disorders presenting as hypertension are primarily the result of autonomous production of renin, aldosterone, cortisol, or catecholamines. This report discusses the physiological changes in pregnancy, presentation, investigation, and management of these disorders.

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.

Noninvasive diagnosis of renovascular disease

OBJECTIVE

To present the epidemiologic and clinical features of renovascular disease and discuss various diagnostic approaches.

DESIGN

We describe the findings in patients with fibromuscular dysplasia or atherosclerotic disease of the renal arteries and review pertinent studies from the literature.

RESULTS

Renovascular disease is an important cause of resistant hypertension and progressive renal insufficiency, particularly in the elderly population. Improved blood pressure control and renal function after revascularization have generated intense interest in identifying those patients likely to benefit from this intervention. Fibromuscular dysplasia and atherosclerotic renal artery stenosis account for most cases of renovascular disease. Both entities produce resistant hypertension; the latter is the more common cause of progressive renal insufficiency--occasionally leading to end-stage renal disease. Angiotensin-converting enzyme inhibitor-related renal dysfunction, otherwise unexplained renal insufficiency, and recurrent pulmonary edema are increasingly recognized clinical manifestations of renovascular disease. Traditional screening tests such as intravenous pyelography, intravenous digital subtraction angiography, radionuclide scintirenography, and measurement of the peripheral venous plasma renin activity have limited accuracy for diagnosing renal artery stenosis and do not accurately predict the blood pressure response to revascularization. In comparison, recently developed noninvasive tests such as captopril renography, renal artery duplex sonography, and magnetic resonance angiography seem to be more accurate and, in the case of captopril renography, may be more predictive of the blood pressure response to revascularization.

CONCLUSION

Future directions in the area of renovascular disease should include a direct comparison among these new noninvasive diagnostic techniques, with a particular focus on the identification of those patients most likely to benefit from revascularization in terms of both blood pressure control and improved renal function.

Surgical correction of renovascular hypertension

The role of surgical revascularization in the management of patients with renal artery disease has changed in recent years. This has occurred owing to the advent of transluminal angioplasty as an effective method of treatment for certain patients, improved results of surgical revascularization in older patients with atherosclerosis, an enhanced appreciation of advanced atherosclerotic renal artery disease as a correctable cause of renal failure, and the development of more effective surgical techniques for patients with severe aortic atherosclerosis and branch renal artery disease. Surgical revascularization is at present the treatment of choice for patients with branch renal artery disease, ostial atherosclerotic renal artery disease, a renal artery aneurysm, and patients in whom renal angioplasty has been unsuccessful. Excellent clinical results continue to be achieved with surgical revascularization in properly selected patients.

Evaluation and preparation for surgical treatment of renal artery disease

The diagnosis of renovascular disease and renovascular hypertension is outlined. A comparison and analysis of the advantages of three forms of treatment are made. These include medical management, percutaneous transluminal coronary angioplasty, and surgical intervention. Selection of patients for revascularization to preserve renal function is discussed, and guidelines for determining renal salvageability are presented. Surgical revascularization is the treatment of choice for patients with ostial atherosclerotic renal artery disease, branch renal artery disease, or a renal artery aneurysm.

Predictive value of angiotensin II blockade with (sarcosine-1, threonine-8) angiotensin II in renovascular hypertension

Administration of an angiotensin II antagonist, (sarcosine-1, threonine-8) angiotensin II, was used to diagnose renovascular hypertension in 22 patients before renal revascularization or nephrectomy. Positive and negative responses to infusion occurred in 12 and 10 patients, respectively. Postoperatively, hypertension was cured in 13 patients, improved in 6 and unchanged in 3. The over-all accuracy of the infusion test in predicting the outcome of surgical therapy was 59 per cent, the false positive rate was 8.3 per cent and the false negative rate was 80 per cent. A similar high incidence of false negative results has been observed with differential renal vein plasma renin assays. The most accurate prediction of the blood pressure response to surgical therapy is obtained by considering multiple factors rather than a single test.

The current status of surgical therapy for renal artery disease

The first reports of surgically curable hypertension in the late 1930s led to enthusiasm among clinicians for removing kidneys with arterial stenosis in hypertensive patients. The development of vascular surgical techniques in the 1950s made it possible to achieve successful renal revascularization in many of these cases. However, the cause and effect relationship between a stenotic renal artery lesion and hypertension was poorly understood and many patients treated surgically had no improvement of blood pressure postoperatively. Continued experience in this field during the past two decades has significantly improved our understanding of the natural history and functional significance of renovascular disorders. Patients with renovascular hypertension can now be identified with a high degree of accuracy and successful renal revascularization is possible in most cases. Nevertheless, multiple factors must be weighed in determining whether medical or surgical therapy is more appropriate for a given patient. These include the causal relationship of renovascular disease to hypertension, the adequacy of blood pressure control with medical therapy, the natural history of untreated renovascular disease with particular regard for the risk of sustaining impaired renal function, the medical condition of the patient, the morbidity and results of surgical therapy, and the availability of other therapeutic options such as percutaneous transluminal dilatation.