Most kidneys work efficiently in cleaning the blood of its impurities while keeping the body's fluids and electrolytes in balance. But sometimes the arteries of the kidneys can narrow or become blocked - which can do incredible damage to this sophisticated filtration system and prevent the kidneys from receiving an adequate blood supply. What are renovascular diseases and can they be cured? The following information will help you talk to your urologist.
What are renovascular diseases?
Renovascular diseases are disorders primarily affecting the arteries of the kidneys and resulting in hypertension and kidney dysfunction.
What are the types of renovascular diseases?
There are primarily two diseases of the renal (kidney) arteries: atherosclerotic renal artery stenosis (AS-RAS) and fibromuscular dysplasia (FMD).
Atherosclerosis (hardening of the arteries) accounts for approximately 90 percent of renovascular disease cases and it may also involve the smaller branches of the renal artery. The prevalence of AS-RAS increases with age, particularly in patients with diabetes, aortoiliac occlusive disease, coronary artery disease or hypertension. Of patients with AS-RAS, progressive abnormal narrowing of the renal artery has been reported in 51 percent five years after the diagnosis has been made and anywhere from 3 to16 percent of the arteries become totally blocked. Shrinkage of the kidney occurs in approximately 20 percent of patients. AS-RAS is a common and progressive disease, particularly in patients with diabetes or other manifestations of hardening of the arteries. Nevertheless, it is likely that many cases are never detected because hypertension or kidney failure does not develop.
FMD is a collection of vascular diseases that affects the various linings of the renal artery and accounts for approximately 10 percent of cases of renal artery stenosis. FMD is more common in women and individuals between the ages of 25 and 50 and frequently involves the main renal artery and its branches. It is characterized by a beaded appearance on kidney angiograms. In contrast to atherosclerosis, FMD rarely leads to total renal artery blockage. The cause of FMD is unknown, although many theories have been advanced including those involving a genetic predisposition, smoking, hormonal factors and disorders of the blood supply to the renal artery itself.
What are the signs of a problem?
Although renovascular disorders often contribute to accelerated or malignant hypertension, it is not readily distinguishable from other forms of hypertension.
Certain classic features – like no family history of hypertension, recent onset of hypertension or the onset of hypertension before the age of 50 – are more suggestive of renovascular hypertension than other forms of high blood pressure.
How are renovascular diseases diagnosed?
Patients with certain clinical features associated with renal artery stenosis are often considered for further evaluation. The evaluation may include studies to assess overall kidney function and/or assess differential blood flow.
Renal angiograms may also be used since they can provide a silhouette of the renal artery that can confirm the diagnosis. A renal angiogram can also identify the cause of the renal artery stenosis, evaluate the extent of the disease and detect associated aneurysms or diseases that block the aorta.
What are some treatment options?
Treatment consists of medication to control hypertension and may also include aspirin and cholesterol-lowering drugs, as well. If the patient is a smoker, it is suggested that he/she stop smoking immediately. High blood pressure pills are very effective in controlling blood pressure, but progressive artery constriction may result in loss of kidney tissue and progressive kidney failure, especially if renal artery stenosis affects both kidneys.
Balloon angioplasty for mural dysplastic disease is approximately 85 percent effective in curing hypertension and preventing progressive kidney failure. In atherosclerotic disease, balloon angioplasty has been supplemented with renal artery stent placements. Research has shown this to be effective for the short term but may not be appropriate for the long term.
Surgical revascularization is indicated when antihypertensive medications, balloon angioplasty and stent placement fail to control the patient's hypertension. Surgical revascularization is also indicated when there is progression of kidney failure. There are a whole host of surgical procedures available, such as aortorenal bypass grafts and extra anatomic bypass procedures. Occasionally, some patients require a surgical procedure called bench surgery. This procedure consists of removal of the kidney with renal artery reconstruction outside the body and then transplantation of the kidney back into the patient after the renal vessels have been reconstructed. Depending upon the nature and severity of the disease, bypass surgery controls the blood pressure in 90 to 95 percent of patients and stabilizes or prevents progressive kidney failure in 85 to 90 percent of patients if the patients are surgically treated before their serum creatinine reaches the level of 3.0.
What can be expected after treatment?
Following treatment, the patient can expect their blood pressure to be improved or cured, as well as an improvement in kidney function. Over a period of 40 months, disease may recur in 15 percent of the patients with mural dysplasia who have undergone balloon angioplasty. Of the patients with atherosclerotic renal artery stenosis treated with balloon angioplasty and stent, 44 percent may note failure to control the blood pressure or progression of kidney failure. Therefore, careful post-treatment follow up is required.
Frequently asked questions:
Can renovascular disease lead to kidney failure?
Yes. Signs of oncoming kidney failure can be: puffy eyes, hands and feet; loss of appetite; nausea and vomiting; a bad taste in the mouth; weight loss; generalized and persistent itchy skin; muscle twitching or cramping; and a yellowish-brown tint to skin color. As the kidney failure gets worse and the toxins continue to build up in the body, seizures and mental confusion can occur.
What are some complications of renovascular disease?
Some complications can include: heart disease, stroke, heart attack, congestive heart failure, blood vessel damage, kidney failure/damage and loss of vision.
Can renovascular disease be prevented?
No. However, its onset may be slowed down by controlling conditions that can cause it, such as hypertension. Eating a healthy diet is always recommended.