Renovascular hypertension

Definition

Renovascular hypertension (high blood pressure) is caused by narrowing of the arteries that carry blood to the kidneys.

Causes, incidence, and risk factors

Renovascular hypertension is a form of secondary hypertension. Most forms of hypertension are considered "essential," and the cause is unknown. But a small number of high blood pressure patients have "secondary hypertension," which means an underlying disease is identified as the cause.

During renovascular hypertension, one or both of the kidney arteries become narrow. This reduces blood flow to the kidneys, and the affected kidney or kidneys mistakenly respond as if the patient's blood pressure is low. They secrete hormones that tell the body to retain salt and water. This causes an increase in blood pressure.

Many different diseases can cause narrowing of the renal arteries. Renal artery stenosis is one of the most common.

Symptoms

Usually, high blood pressure causes no symptoms. Occasionally, you may experience a mild headache. If your headache is severe, or if you experience any of the symptoms below, see a doctor right away. These may be a sign of malignant hypertension.

• tiredness
• confusion
• vision changes
• crushing, angina-like chest pain
• heart failure
• blood in urine
• nosebleed
• irregular heartbeat
• ear noise or buzzing

Certain signs and symptoms may point towards the diagnosis of renovascular hypertension. These include:

• Severe, difficult-to-control hypertension. Renovascular hypertension is often severely high and difficult to treat.
• A "whooshing" noise, or bruit, which may be heard when placing a stethoscope over the abdominal (flank) area.
• Episodes of heart failure (flash pulmonary edema).
• Rapid progression of kidney failure.
• Acute renal failure which occurs when starting ACE-I or ARB type medicines.
• Sudden aggravation of hypertension in an elderly patient whose blood pressure was previously well controlled.

Signs and tests

Elevated blood pressure measurements, repeated over time, confirm hypertension.

There may also be signs of complications, such as:

• Left ventricular hypertrophy (swelling of the heart)
• Hypertensive retinopathy
• Presence of a bruit

Visualization methods to see artery narrowing (atherosclerosis or renal stenosis) include:

• Renal arteriography (injection of dye into the renal artery so that a narrowing of the artery can be seen on an x-ray)
• Doppler ultrasound of the renal arteries
• Magnetic Resonance Angiography (MRA)
• Angiotensin converting enzyme (ACE) inhibition renography

Blood tests may also be performed to check renin and aldosterone levels.

Treatment

The first treatment step involves controlling the high blood pressure with medication.

Medications that may be used in an attempt to control blood pressure include diuretics, beta blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs) and alpha blockers.

Response to medications is highly individual. Blood pressure should be monitored frequently. Medication and dosage may need frequent adjustment.

Further mangement of the disease depends on its underlying cause. In some cases, surgical reconstruction of a damaged artery may be performed. Patients with fibromuscular dysplasia, a vascular disease that causes narrowing of the renal arteries, may benefit from percutaneous transluminal renal angioplasty (PRTA) using a stent. This cures hypertension in a good percentage of patients, and makes it easier to control in the rest.

Most nephrologists will attempt to a surgical bypass of the renal arteries (revascularization) to restore blood flow in patients who have severe, refractory hypertension, episodes of flash pulmonary edema or rapid progression of renal failure.

Expectations (prognosis)

Renovascular hypertension in the elderly is a difficult clinical problem. It requires careful review and monitoring with frequent tests, sometimes invasive, to arrive at the best individualized solution, whether medical therapy or surgery.

Complications

• early death
• hypertensive heart disease
• heart attack
• congestive heart failure
• blood vessel damage
• kidney damage
• kidney failure
• stroke
• loss of vision

Calling your health care provider

Call for an appointment with your health care provider if hypertension is suspected.

Call your health care provider if renovascular hypertension has been diagnosed and symptoms occur, worsen, or do not improve with treatment. Also call if new symptoms develop.

Prevention

Preventing atherosclerosis may prevent the development of renal artery stenosis.

Lifestyle changes may reduce the risk of hypertension. Lose weight if you are overweight. Excess weight adds to efforts of the heart. Exercise to improve cardiac fitness (check with the health care provider before beginning a rigorous exercise program).

Dietary adjustments may help to control hypertension. Modify your sodium intake. (Sodium intake may have little effect in people without hypertension but may have a profound effect in those with hypertension). Salt, MSG, and baking soda all contain sodium.

Illustrations

Hypertensive kidney

Page Content:

Renal hypertension; Hypertension - renovascular ; renovascular hypertension; renal hypertension; renal vascular hypertension