Renal artery stenosis facts. What are the renal arteries? Renal refers to anything related to the kidneys, renal artery and blood pressure control.
Renal arteries carry blood from the heart to the kidneys. They branch directly from the aorta the main artery coming off the heart on either side and extend to each kidney.
These arteries take a very large volume of blood to the kidneys to be filtered. The heart pumps out approximately 5 liters of blood per minute, and about What is renal artery stenosis?
Renal artery stenosis narrowing is a decrease in the diameter of the renal arteries. The resulting restriction of blood flow to the kidneys may lead to impaired kidney function renal failure and high blood pressure hypertensionreferred to as renovascular hypertensionor RVHT "reno" for kidney renal artery and blood pressure control "vascular" for blood vessel.
Renovascular hypertension is as likely to occur with bilateral stenosis when arteries to both kidneys are narrowed as with unilateral stenosis when the artery to one kidney is narrowed.
The decreased blood flow to the kidneys impairs renal function. Renal artery stenosis may cause renal failure in some patients. There is no predictable relationship between renal failure and renal artery stenosis. Some patients have very severe bilateral stenosis renal artery and blood pressure control normal renal function. Most cases of renal failure are related to diabeteshypertension, glomerular sclerosis, contrast nephropathydrug toxicity and other causes.
What are the causes of renal artery stenosis? The majority of renal artery stenosis is caused by atherosclerosis hardening and narrowing of blood vessel wall from the inside similar to the process that occurs in blood vessels in the heart and other parts of the body. How common is renal artery stenosis? Narrowing of the kidney arteries is more common renal artery and blood pressure control individuals 50 years of age and older.
This may be due to the fact that atherosclerosis is more common in this age group. In younger patients, the narrowing of the renal artery usually is due to the thickening of the artery fibromuscular dysplasia and it is more common in women than men. What are the symptoms of renal artery stenosis? In general, renal artery stenosis is not associated with any obvious or specific symptoms. Suspicious signs for renal artery stenosis include:. Typically, renal artery and blood pressure control, unilateral one-sided renal artery stenosis may be related to high blood pressure whereas bilateral two-sided renal artery stenosis is more often related to diminished kidney function.
What problems does renal artery stenosis cause? When the circulating spiriva and stroke volume becomes depleted as a result of, for example, dehydration or bleeding, the blood flow to the kidneys is likewise reduced. The normal physiologic reaction to a decrease in blood flow to the kidneys is a complex hormonal response by the kidneys, called the renin-angiotensin-aldosterone system.
This hormonal system is activated as a defense against low blood pressure and low circulating blood volume. The kidney senses a possible decrease in the circulating blood when blood flow through these vessels is reduced. As a result, there are increased blood levels of the hormone angiotensin 2, which causes narrowing of the small blood vessels in the kidneys.
This, together with increased blood aldosterone levels another hormonepromotes salt retention by the kidneys, and works to maintain blood pressure and restore blood volume. Accordingly, this hormonal system is protective in response to reduced circulation of blood to the kidneys that is caused either by volume depletion, as described, renal artery and blood pressure control, or by reduced blood pressure. This otherwise normal hormonal response can become abnormal pathologic when the decreased blood flow to the kidneys results from a narrowing of diseased renal arteries.
In this situation, the kidneys receive less blood flow, which then signals a sense of depletion of the circulating blood volume, despite the fact that the blood volume is actually normal. So, the diminished renal blood flow, by stimulating the production of angiotensin 2 and aldosterone, can lead to an abnormal increase of blood pressure renovascular hypertension.
Who should be screened for renal artery stenosis? A search for renal artery stenosis may be undertaken in patients with progressive kidney failure of unknown cause, or in individuals with difficult to treat high blood pressure hypertension that does not respond well to medications. The diagnosis of renal artery stenosis may be considered when any or all of the following are present:. How is renal artery stenosis diagnosed? Several tests exist to detect any evidence of renal artery stenosis.
They can be divided into imaging tests and pull up and dip bar plans tests. The imaging tests provide a picture of the blood vessel and its anatomy and reveal the degree of narrowing. The functional tests provide information about whether the narrowing is significant enough to cause the high blood pressure or kidney dysfunction. Each of these tests has advantages and shortcomings, renal artery and blood pressure control.
What are the common imaging tests to evaluate renal artery stenosis? An angiogram of the renal arteries is the best test available to detect the degree of narrowing.
However, angiography is not the primary test and is performed only for those patients who have evidence of stenosis on less invasive testing, such as ultrasoundCT Angio, or MR Angio, renal artery and blood pressure control. Angiography is a preliminary portion of a procedure, which will generally culminate in angioplasty and possibly stenting to treat a stenosis identified on less invasive testing. The angiogram of the renal arteries is similar to an angiogram of the heart and involves insertion of a catheter through the groin into the main artery the aortathat is advanced to the level of the renal arteries.
These tests are most commonly performed through the groin, but arteries in other parts of the body, such as the arms, can be used equally well. A dye is injected, and x-ray images are taken to see the caliber of the blood vessel and extent of the stimulus plan and student loan. An angiogram is considered an invasive test insertion of the catheter renal artery and blood pressure control the body and therefore is not widely used because of the risk of complications.
This test also may not determine if narrowing is truly significant to cause the problem or not, and so it may be necessary to combine this with a functional test. An additional advantage of an angiogram is that if a treatable narrowing is seen, it may be fixed at the same time via angioplasty or by placing a stent described in more detail below. Other less invasive imaging tests are available to detect renal artery stenosis, but they are not generally as accurate as the angiogram and could potentially miss some cases of correctable disease.
The most commonly used additional imaging tests are:. Contrast dye is injected into the blood via a vein in the arm, and pictures of the specific area of the body in this case the renal arteries are taken and analyzed. The accuracy specificity and sensitivity of this test is reasonable.
This test cannot be done in patients with metal implants, pacemakers, or claustrophobia fear of closed spaces. It may be used in people with mild to moderate, but not severe, kidney problems, renal artery and blood pressure control.
Computed tomographic angiography is similar to a computed tomography CT scan and has reasonable accuracy. This is also done by injecting a contrast dye into the blood and taking pictures of the renal arteries. This is not recommended in people with moderate to severe kidney problems as it may make the problem worse.
Doppler ultrasound is the least invasive imaging test for renal artery stenosis. It is performed similarly to a regular ultrasound by placing a probe on the abdomen to visualize the flow across the renal arteries and also to measure any narrowing. Its accuracy is similar to the other tests above, but its advantage is that it can measure the size of the narrowing as well as the flow across it.
The disadvantage of this test is that it is time-consuming and may take up to a couple of hours to complete. It is also very operator-dependent, meaning that the accuracy of the result is dependent upon the expertise and experience of the ultrasound technician. What functional tests are used for the diagnosis of renal artery stenosis? The main functional tests for renal artery stenosis include the plasma renin activity test and captopril renogram.
These tests have been largely replaced gojo antibacterial foam soap the imaging tests described above because they are less accurate, but they may be still performed to help establish the diagnosis of renal artery stenosis. The plasma renin activity measures the activity of the hormone renin described above.
Activity of renin is generally higher in the kidney with renal artery stenosis compared to the other kidney. This response may be exaggerated by administration of captopril Capotenan ACE inhibitor medication used to treat high blood pressure.
The renogram measures the activity of the kidneys after injection of a radioactive material that is taken up by the kidney. By administering captopril prior to the test, the activity may become more enhanced on the normal kidney compared to the one with renal artery stenosis. This may indicate a significant renal artery narrowing on the side with less activity. What are medical treatments for renal artery stenosis?
In bilateral both-sided and unilateral one-sided renal artery stenosis associated with high blood pressure, controlling the blood pressure with usual blood pressure medications is the first and the safest treatment. This approach may lead in some patients to worsening of their kidney function. Therefore, kidney function needs to be followed closely and if worsening of kidney function is evident, these medications renal artery and blood pressure control need to be stopped.
It is worth noting that if renal artery stenosis is found incidentally when performing a test for another disease and there is no evidence of kidney dysfunction or high blood pressure, then no treatment may be necessary. Sometimes even significant stenosis may not renal artery and blood pressure control associated with high blood pressure or kidney dysfunction. In these situations, periodic monitoring of blood pressure and kidney function may be advised. What surgical procedures are available for renal artery stenosis?
If the results of any of these screening tests suggest an abnormality of the renal artery, an x-ray angiography is then performed. Usually right at the time of the angiography, an angioplasty is done. In this procedure a tiny balloon is inflated in the interior space in the artery the lumen to dilate the narrowed artery.
Additionally, as part of the angioplasty procedure, a stent tubular device to prevent recurrence of the narrowing may be placed in the artery. In rare cases, vascular surgery on the blood vessels may be done for renal artery stenosis.
In these situations, typically another vascular surgery near the renal renal artery and blood pressure control, for example the aorta, is the main procedure. If renal artery and blood pressure control artery stenosis is also present, then a bypass renal artery surgery may be done at the same time.
These invasive procedures are extreme anger and associated mental illness reserved for cases that do not respond to medical treatment and where it has been determined that the stenosis is renal artery and blood pressure control or contributing to the uncontrolled high blood pressure. These invasive procedures may only be done if it is thought that the kidney dysfunction or elevated blood pressure can be effectively treated with the procedures.
Which patients can benefit from surgical procedures for renal artery stenosis? In patients with renal failure due to bilateral renal artery stenosis narrowing on both kidneysangioplasty procedures for both renal arteries may improve or stabilize kidney function. Similarly, in hypertensive patients with unilateral one-sided renal artery stenosis, angioplasty procedures of the involved renal artery may cure or improve the high blood pressure.