Renal artery stenosis is a narrowing of the renal artery. This artery supplies the associated kidney with oxygen-rich blood. This so-called stenosis can occur on one or both sides and can lead to high blood pressure due to various mechanisms.
Here you will find further information and selected doctors for renal artery stenosis.
The kidneys are paired abdominal organs - there is one on each side. Normally, they are each supplied with oxygen-rich blood by one renal artery, the renal artery. This artery branches off from the main artery(aorta) on both sides at the level of the first or second lumbar vertebra.
The kidney is important for purifying the blood and controlling blood pressure. If the blood pressure drops, for whatever reason, the kidney counteracts this by various mechanisms in order to raise the blood pressure again. Only when the blood pressure is sufficiently high can the kidney perform its filter function (purification of the blood) properly.
Renal artery stenosis refers to the narrowing of the renal artery. This means that less blood and therefore less oxygen reaches the affected kidney. In addition, the pressure downstream of the narrowing is lower, which simulates a drop in blood pressure throughout the body. The kidney therefore tries to increase the blood pressure, which leads to normal pressure in the kidneys, but to increased blood pressure ("high blood pressure" or arterial hypertension) in the entire body.
Renal artery stenosis is widespread in industrialized countries. Almost half of all people over the age of 75 are affected. According to estimates and studies, up to five percent of all cases of high blood pressure are due to renal artery stenosis.
The location of the kidneys and the urinary system © SciePro | AdobeStock
If the stenosis develops after the age of 50, it is usually due to atherosclerosis. This is the deposition of connective tissue, calcium, fat and blood clots in the arterial blood vessels, but it is also referred to as vascular calcification. These plaques make the vessel wall more rigid and the vessel diameter smaller, so that the blood can no longer flow properly.
There are various risk factors that can promote the development of atherosclerosis. These include
In younger patients, renal artery stenosis develops primarily due to fibromuscular dysplasia(FMD). Here, the arterial wall thickens for as yet unknown reasons. Renal artery stenosis can also be caused by vascular inflammation such as panarteritis nodosa or Takayasu's arteritis.
The main symptom of renal artery stenosis is arterial hypertension. As this is caused by kidney disease, it is also known in medicine as renal hypertension. However, the filter function of the kidney is also impaired by upstream renal artery stenosis, which is reflected in symptoms such as
can become noticeable.
Arterial hypertension due to renal artery stenosis is primarily mediated by the Goldblatt mechanism. Due to the stenosis, less blood reaches the kidney, so that the blood pressure in the blood vessels of the organ is lower. Special receptors in the kidney constantly measure the pressure in the renal arteries. If this is too low, the kidney releases the hormone renin.
This activates the so-called renin-angiotensin-aldosterone mechanism. This results in a gradual increase in arterial blood pressure by
The blood pressure in the body then rises so that more blood enters the kidneys. As a result, the pressure in the renal vessels rises to a roughly normal level due to the stenosis. However, arterial hypertension is present in the remaining vessels of the body.
However, high blood pressure only develops when the blood vessel is more than 75 percent obstructed.
High blood pressure can manifest itself through various symptoms such as
become noticeable. Blood pressure is often not or hardly noticed, which is the most dangerous aspect of this disease. Untreated high blood pressure can lead to permanent damage to all tissues and organs, for example the eyes, blood vessels or the brain.
If a blood clot (thrombus) becomes lodged in the artery and causes a complete blockage, a kidney infarction occurs.
Due to the lack of blood flow and supply of nutrients and oxygen, parts of the kidney tissue are destroyed. A pronounced kidney infarction manifests itself through symptoms such as
If no other organic cause of high blood pressure is found, renal artery stenosis is suspected. Other indications of stenosis of the renal arteries include
During the physical examination, a stethoscope is used to listen to the patient's abdomen and back. This reveals a flow noise in almost half of all patients with renal artery stenosis.
To confirm the suspected diagnosis, imaging procedures such as
are used.
The DSA procedure in particular allows a precise assessment of the vascular condition. However, this procedure requires greater effort and is also comparatively stressful. It is therefore only used if magnetic resonance imaging or ultrasound do not provide a clear result.
If renal artery stenosis is caused by atherosclerosis, patients should always avoid risk factors. These include smoking, for example. A long-term change to a healthier lifestyle is required. In addition, antihypertensive medication is essential to reduce the elevated blood pressure to normal levels.
If the blood pressure cannot be lowered despite the medication, dilatation of the constriction using a balloon catheter should be discussed. This is called percutaneous transluminal angioplasty (PTA).
PTA with stent implantation in a narrowed blood vessel © Christoph Burgstedt | AdobeStock
A metal mesh tube (stent) that remains permanently in the vessel can keep the renal artery open.
If the vascular bottleneck is bridged using a prosthesis, this is known as a vascular bypass. In contrast to PTA, however, this requires the abdominal wall to be opened.
Without treatment, the renal artery can become increasingly narrow and the stenosis can develop into renal insufficiency over time.
Without treatment, high blood pressure often leads to cardiovascular disease and damage to all tissues. It should definitely be treated with medication, whereby several drugs are often necessary.
Fibromuscular renal artery stenosis in younger women usually normalizes in over 70 percent of patients after treatment. The prognosis here is significantly better than for patients with renal artery stenosis caused by vascular calcification (atherosclerosis).
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