renovascular hypertension


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Renovascular Hypertension

 

Definition

Renovascular hypertension is a secondary form of high blood pressure caused by a narrowing of the renal artery.

Description

Primary hypertension, or high blood pressure, affects millions of Americans. It accounts for over 90% of all cases of hypertension and develops without apparent causes. It is helpful for the clinician to know if a secondary disease is present and may be contributing to the high pressure. If clinical tests indicate this is so, the term used for the rise in blood pressure is secondary hypertension.
Renal hypertension is the most common form of secondary hypertension and affects no more than one percent of all adults with primary hypertension. There are two forms of renovascular hypertension.
In atherosclerotic renovascular hypertension disease, plaque is deposited in the renal artery. The deposits narrow the artery, disrupting blood flow. Atherosclerotic renovascular hypertension is most often seen in men over age 45 and accounts for two-thirds of the cases of renovascular hypertension. In most patients, it affects the renal arteries to both kidneys.
Renovascular hypertension caused by fibromuscular dysplasia occurs mainly in women under age 45. It is also the cause of hypertension in 10% of children with the disorder. In fibromuscular dysplasia, cells from the artery wall overgrow and cause a narrowing of the artery channel.
The risk of having hypertension is related to age, lifestyle, environment, and genetics. Smoking, stress, obesity, a diet high in salt, exposure to heavy metals, and an inherited predisposition toward hypertension all increase the chances that a person will develop both primary and renovascular hypertension.

Causes and symptoms

Narrowing of the renal artery reduces the flow of blood to the kidney. In response, the kidney produces the protein renin. Renin is released into the blood stream. Through a series of steps, renin is converted into an enzyme that causes sodium (salt) retention and constriction of the arterioles. In addition to atherosclerotic and fibromuscular dysplasia, narrowing of the renal artery can be caused by compression from an injury or tumor, or by blood clots.
Renovascular hypertension is suspected when hypertension develops suddenly in patients under 30 or over 55 years of age or abruptly worsens in any patient. Symptoms are often absent or subtle.

Diagnosis

No single test for renovascular hypertension is definitive. About half of patients with renovascular hypertension have a specific cardiovascular sound that is heard when a doctor listens to the upper abdomen with a stethoscope. Other diagnostic tests give occasional false positive and false negative results. Most tests are expensive, and some involve serious risks.
Imaging studies are used to diagnose renovascular hypertension. In intravenous urography, a dye is injected into the kidney, pictures are made, and the kidneys compared. In renal arteriography, contrast material is inserted into the renal artery and cinematic x rays (showing motion within the kidney) are taken. Studies of kidney function are performed. Tests are done to measure renin production. The results of these tests taken together are used to diagnose renovascular hypertension.

Treatment

Renovascular hypertension may not respond well to anti-hypertensive drugs. Percutaneous transluminal angioplasty (PTA), where a balloon catheter is used to dilate the renal artery and remove the blockage, is effective in improving the condition of about 90% of patients with fibromuscular dysplasia. One year later, 60% remain cured. It is less successful in patients with atherosclerosis, where renovascular hypertension recurs in half the patients. Where kidney damage occurs, surgery to repair or bypass the renal artery blockage is often effective. In some cases, the damaged kidney must be removed.

Alternative treatment

Alternative treatment stresses eliminating the root causes of hypertension. With renovascular hypertension, as with primary hypertension, the root causes generally cannot be totally reversed by any method. Lifestyle changes are recommended. These include stopping smoking, eating a diet low in animal fats and salt, avoiding exposure to heavy metals, stress control through meditation, and anger management. Herbal medicine practitioners recommend garlic (Allium sativum) to help lower blood pressure. Constitutional homeopathy and acupuncture also can be helpful in lowering blood pressure.

Prognosis

PTA is effective in many younger patients with fibromuscular dysplasia. Older patients are less responsive to this treatment. Surgery is also more risky and less successful in older patients.

Prevention

Renovascular hypertension is possibly preventable through lifestyles that prevent atherosclerosis and primary hypertension. It is unknown how to prevent fibromuscular hyperplasia

Resources

Organizations

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

re·no·vas·cu·lar hy·per·ten·sion

hypertension produced by renal arterial obstruction.

renovascular hypertension

Atherosclerotic renal artery disease, atherosclerotic renovascular disease, renal hypertension Nephrology Systemic HTN due to renal artery obstruction by ASHD, fibroplastic disease, aneurysms, embolism High risk ASHD, smoking, white, abdominal bruits, peripheral vascular disease, late–> age 60, onset of HTN Clinical Hemorrhage in cerebellum, pons, internal capsule, basal ganglia Treatment–medical Empirical, a function of disease severity and response to therapy–eg, diuretics, β blockers, vasodilators, ACE inhibitors Treatment-interventional Percutaneous transluminal angioplasty of renal artery, 60-70% success in atherosclerosis; 90% success in fibromuscular hyperplasia. See Goldblatt kidney, Hypertension.

re·no·vas·cu·lar hy·per·ten·sion

(rē'nō-vas'kyū-lăr hī'pĕr-ten'shŭn)
Hypertension produced by renal arterial obstruction.
References in periodicals archive ?
The findings of the present study show that the placement of solid plexiglass clips on the left renal arteries results in renovascular hypertension associated with attenuated release of NO and increased oxidative stress.
Results of surgical treatment for renovascular hypertension in children: 30-year single centre experience.
Renovascular hypertension is most commonly caused by artherosclerosis or fibromuscular dysplasia.
The patients formed two groups: group A, consisting of 14 patients with renovascular hypertension and systolic dysfunction of left ventricle and group B, consisting of 14 geriatric patients, with normal blood pressure values.
Increased oxidative stress in experimental renovascular hypertension," Hypertension, vol.
Renovascular hypertension was associated with a 3-4-fold increase in ACE activity in the non-clipped and clipped kidneys, respectively.
Renin and aldosterone are characteristically increased (but are sometimes normal), and the aldosterone/ renin ratio is normal or low, in cases of secondary hyperaldosteronism that may occur in hypertensive patients who have been treated with thiazide diuretics and patients with renovascular hypertension or the rare reninoma.
Identifiable Causes of Hypertension Chronic kidney disease Coarctation of the aorta Cushing's syndrome and other glucocorticoid excess states including chronic steroid therapy Drug induced or drug related Obstructive uropathy Pheochromocytoma Primary aldosteronism and other mineralocorticoid excess states Renovascular hypertension Sleep apnea Thyroid or parathyroid disease Adopted from the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure Table 7.
Other clinical conditions that have been identified as contributing to the development of flash pulmonary edema include: a) myocardial ischemia, b) acute aortic insufficiency, c) acute mitral regurgitation, d) mitral stenosis, and e) renovascular hypertension (Walker, Walker, & Nielsen, 2001), but this paper will primarily focus on diastolic heart failure as it relates to development of flash pulmonary edema because diastolic heart failure has received less attention and yet is believed to be highly prevalent.
Based on the literature, successful revascularization is rare after 19 hours of renal ischemia, although there is at least one report of restored renal function postrevascularization with a prolonged ischemia time of 48 hours (7) The reported risk of renovascular hypertension after revascularization range from 3 to 33%.
A knowledge of the variations of renal vascular anatomy has importance in exploration and treatment of renal trauma, renal transplantation, renovascular hypertension, renal artery embolization, angioplasty or vascular reconstruction for congenital and acquired lesions, surgery for abdominal aortic aneurysm and conservative or radical renal surgery (Sampaio & Aragao, 1990).