Renovascular hypertension
Encyclopedia
Renovascular hypertension (or "renal hypertension
") is a syndrome
which consists of high blood pressure
caused by narrowing of the arteries supplying the kidneys (renal artery stenosis
). It is a form of secondary hypertension
- a form of hypertension whose cause is identifiable.
Cause:
It induces renin secretion that causes the angiotensin
conversion, causing aldosterone
release and then water retention and potassium depletion.
of radiographs. Treatment may involve angioplasty
and stent
ing of the renal arteries. The syndrome may be related to other diseases of the epithelium
.
Suggestive clinical features include onset of hypertension <30 or >50 years of age, abdominal or femoral bruits, hypokalemic alkalosis, moderate to severe retinopathy, acute onset of hypertension or malignant hypertension
, and hypertension resistant to medical therapy.
The "gold standard" in diagnosis of renal artery stenosis is conventional arteriography. Magnetic resonance angiography
(MRA) is used in many centers, especially among patients with renal insufficiency at higher risk for contrast nephropathy. MRA may overestimate the severity of stenosis relative to angiography. In patients with normal renal function and hypertension, the captopril (or enalaprilat) renogram may be used. Lateralization of renal function [accentuation of the difference between affected and unaffected (or "less affected") sides] is suggestive of significant vascular disease. Test results may be falsely negative in the presence of bilateral disease.
) axis; ACE inhibitor
s and angiotensin II receptor blocker
classes of antihypertensives are contraindicated as they might compromise the renal function especially if the stenosis is bilateral. Nitroprusside, labetalol
, or calcium antagonists are generally effective in lowering blood pressure acutely, although inhibitors of the RAA axis [e.g., ACE inhibitors, angiotensin II receptor blockers (ARBs)] are most effective long-term treatment, if disease is not bilateral.
Surgical revascularization appears to be superior for ostial lesions characteristic of atherosclerosis
. The relative efficacy of surgery compared with angioplasty (especially with stenting) for fibromuscular dysplasia or for non-occlusive, non-ostial atherosclerotic disease is unclear. Angioplasty (with or without stenting) tends to be temporarily effective for some cases. However, as of early 2011, six randomized controlled trials have failed to demonstrate any real benefit in blood pressure control or preservation of renal function when using endovascular (angioplasty or stenting) procedures compared to medical therapy alone.
ACE inhibitors or ARBs are ideal agents for hypertension associated with renal artery stenosis, except in patients with bilateral disease (see "Ischemic Nephropathy" below) or disease in a solitary kidney (including an allograft).
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Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
") is a syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
which consists of high blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
caused by narrowing of the arteries supplying the kidneys (renal artery stenosis
Renal artery stenosis
Renal artery stenosis is the narrowing of the renal artery, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney...
). It is a form of secondary hypertension
Secondary hypertension
Secondary hypertension is a type of hypertension which by definition is caused by an identifiable underlying secondary cause. It is much less common than the other type, called essential hypertension, affecting only 5% of hypertensive patients. It has many different causes including endocrine...
- a form of hypertension whose cause is identifiable.
Cause:
It induces renin secretion that causes the angiotensin
Angiotensin
Angiotensin, a peptide hormone, causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure. Angiotensin also stimulates the release of aldosterone, another hormone, from the adrenal cortex...
conversion, causing aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
release and then water retention and potassium depletion.
Diagnosis and presentation
Techniques have been developed to diagnose renal hypertension using digital image processingDigital image processing
Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing...
of radiographs. Treatment may involve angioplasty
Angioplasty
Angioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size...
and stent
Stent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
ing of the renal arteries. The syndrome may be related to other diseases of the epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
.
Suggestive clinical features include onset of hypertension <30 or >50 years of age, abdominal or femoral bruits, hypokalemic alkalosis, moderate to severe retinopathy, acute onset of hypertension or malignant hypertension
Malignant hypertension
Malignant hypertension or hypertensive emergency is severe hypertension with acute impairment of an organ system and the possibility of irreversible organ-damage...
, and hypertension resistant to medical therapy.
The "gold standard" in diagnosis of renal artery stenosis is conventional arteriography. Magnetic resonance angiography
Magnetic Resonance Angiography
Magnetic resonance angiography is a group of techniques based on Magnetic Resonance Imaging to image blood vessels. Magnetic resonance angiography is used to generate images of the arteries in order to evaluate them for stenosis , occlusion or aneurysms...
(MRA) is used in many centers, especially among patients with renal insufficiency at higher risk for contrast nephropathy. MRA may overestimate the severity of stenosis relative to angiography. In patients with normal renal function and hypertension, the captopril (or enalaprilat) renogram may be used. Lateralization of renal function [accentuation of the difference between affected and unaffected (or "less affected") sides] is suggestive of significant vascular disease. Test results may be falsely negative in the presence of bilateral disease.
Treatment
Renal hypoperfusion activates renin-angiotensin-aldosterone (RAARAA
-RAA:* Research on Armenian Architecture* Ralph Appelbaum Associates* Recreation and Amusement Association, a system of brothels set up by the Japanese government for US occupation forces* Recreational Aircraft Association* Recreational Aviation Australia...
) axis; ACE inhibitor
ACE inhibitor
ACE inhibitors or angiotensin-converting enzyme inhibitors are a group of drugs used primarily for the treatment of hypertension and congestive heart failure...
s and angiotensin II receptor blocker
Angiotensin II receptor antagonist
Angiotensin II receptor antagonists, also known as angiotensin receptor blockers , AT1-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system...
classes of antihypertensives are contraindicated as they might compromise the renal function especially if the stenosis is bilateral. Nitroprusside, labetalol
Labetalol
Labetalol is a mixed alpha/beta adrenergic antagonist, which is used to treat high blood pressure.-Indications:...
, or calcium antagonists are generally effective in lowering blood pressure acutely, although inhibitors of the RAA axis [e.g., ACE inhibitors, angiotensin II receptor blockers (ARBs)] are most effective long-term treatment, if disease is not bilateral.
Surgical revascularization appears to be superior for ostial lesions characteristic of atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
. The relative efficacy of surgery compared with angioplasty (especially with stenting) for fibromuscular dysplasia or for non-occlusive, non-ostial atherosclerotic disease is unclear. Angioplasty (with or without stenting) tends to be temporarily effective for some cases. However, as of early 2011, six randomized controlled trials have failed to demonstrate any real benefit in blood pressure control or preservation of renal function when using endovascular (angioplasty or stenting) procedures compared to medical therapy alone.
ACE inhibitors or ARBs are ideal agents for hypertension associated with renal artery stenosis, except in patients with bilateral disease (see "Ischemic Nephropathy" below) or disease in a solitary kidney (including an allograft).
Source
- Harrison's Manual of Medicine: Renovascular Disease - Renal Artery Stenosis
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See also
- Hypertensive nephropathyHypertensive nephropathyHypertensive nephropathy is a medical condition referring to damage to the kidney due to chronic high blood pressure....
- Renal artery stenosisRenal artery stenosisRenal artery stenosis is the narrowing of the renal artery, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney...
- Renal failureRenal failureRenal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
- Fibromuscular dysplasiaFibromuscular dysplasiaFibromuscular dysplasia, or fibromuscular dysplasia of arteries, often abbreviated as FMD, is a disease that can cause narrowing of arteries in the kidneys, the carotid arteries supplying the brain, and, less commonly, the arteries of the abdomen...