Hypertension, renal insufficiency, and edema may be caused by renal artery stenosis!

Author: Zou Yinghua, Chief Physician, Peking University First Hospital

Reviewer: Shen Chenyang, Chief Physician, Beijing Tiantan Hospital, Capital Medical University

Everyone knows that humans have two kidneys, one on each side, and one kidney is enough to sustain life. It is for this reason that stenosis of one renal artery is not easy to detect.

Renal artery stenosis simply means that the renal artery has become thinner. In medicine, it mainly refers to the local narrowing of the renal artery.

Figure 1 Original copyright image, no permission to reprint

1. What are the causes of renal artery stenosis?

The cause of renal artery stenosis is the same as that of other arteries in the body, such as coronary arteries, cerebral blood vessels, and lower limb blood vessels. The main cause of stenosis is atherosclerosis. More than 90% of renal artery stenosis is caused by atherosclerosis.

Simply put, atherosclerosis is the deposition of lipids or cholesterol in the intima or on the surface of the intima of the blood vessel wall. The more lipids or cholesterol deposited, the more plaques are formed. The plaques will rupture and fall off, causing vascular embolism after falling off. At the same time, because the surface of the plaque is not smooth after rupture, blood clots are easily formed, aggravating the stenosis of the blood vessels.

Of course, there are some other rare causes, such as Takayasu arteritis, which is mainly seen in young women; and another part is fibromuscular dysplasia, a congenital disease. These two together account for less than 10%.

The most common disease among the middle-aged and elderly is renal artery stenosis caused by atherosclerosis. Atherosclerosis has both congenital and acquired factors. The so-called congenital factors are genes, or heredity. If parents or grandparents have a high incidence of atherosclerosis, then the risk of the disease is high. Bad congenital factors, coupled with acquired factors, such as eating and drinking too much, not being able to control your diet, smoking, diabetes, high blood lipids, high blood pressure, etc., will promote the occurrence of atherosclerosis.

2. What symptoms may occur in renal artery stenosis?

The early symptoms of renal artery stenosis are relatively hidden, but they will become apparent to a certain extent.

First, high blood pressure. High blood pressure is very common in adults. According to a survey in our country, the incidence of high blood pressure in people over 18 years old is over 20%, which is very high. However, not all of them are caused by renal artery stenosis, only a part of them is. Generally speaking, high blood pressure develops very quickly, the blood pressure is very high, and the medication control effect is not good. In this case, the renal artery should be checked to see if there is stenosis.

Second, renal function declines, which is medically called renal insufficiency. Early renal artery stenosis often does not cause renal function decline. When renal artery stenosis is more serious, especially bilateral renal artery stenosis, it will cause renal function decline and complete loss of renal excretion function. Toxins, metabolic wastes in the body cannot be excreted from the body. At this time, dialysis has to be used to replace renal excretion.

Third, edema. Patients with renal artery stenosis will experience water accumulation in the lower limbs, head and face, and even inside the body, which is edema. For example, after undergoing renal artery stenosis surgery, they will urinate a lot that night, even 4000ml or 5000ml of urine, and they will be much lighter when they weigh themselves the next day.

Renal artery stenosis may occasionally cause symptoms of angina pectoris, such as chest tightness and shortness of breath. If suspected symptoms of angina pectoris occur and examination of the heart shows no abnormalities, you should consider the possibility of renal artery stenosis.

Simply put, renal artery stenosis has three main symptoms: first, high blood pressure; second, renal insufficiency; and third, water and sodium retention, which are actually the main hazards caused by renal artery stenosis.

According to investigations, if renal artery stenosis is not intervened, more than 50% of renal artery stenosis will worsen during the three-year follow-up period, and about 10% of the renal arteries will be closed, which means they are completely blocked. It will be very difficult to reopen them after they are closed. The kidneys will atrophy and renal function will decline, eventually leading to renal insufficiency, which is uremia.

3. What tests can be used to diagnose renal artery stenosis?

From the doctor's perspective, color ultrasound is still the preferred clinical examination method. Color ultrasound is non-destructive, has no radiation, and is easy to obtain. Its disadvantage is that it is greatly affected by the doctor's skills and the doctor's own understanding of the disease.

If the color Doppler ultrasound does not report stenosis, or the prompt is negative, but the clinical symptoms are very similar to renal artery stenosis, further examination will be performed.

The next step is direct imaging, the most commonly used of which is CT angiography, called CTA, which can see the renal artery. However, it also has disadvantages, that is, it requires the creation of contrast agents. Patients with renal insufficiency are recommended to do magnetic resonance imaging.

4. How to treat renal artery stenosis?

Renal artery stenosis is like other vascular stenosis. Mild stenosis mainly refers to stenosis of less than 50%. It does not affect renal function or cause symptoms. Excessive intervention is not recommended, mainly improving lifestyle habits and drug treatment.

Improve your lifestyle, such as quitting smoking, increasing physical exercise, eating less greasy food, and reducing fat intake. For drug treatment, primary diseases such as diabetes and hypertension should be actively controlled and treated, including the use of antithrombotic drugs.

Severe stenosis of more than 70% of the renal artery may result in, first, concurrent hypertension, especially hypertension that is not effectively treated with medication; second, recent deterioration of renal function due to renal artery stenosis; third, edema caused by renal artery stenosis may lead to heart problems, such as symptoms similar to angina pectoris and myocardial infarction. These patients should be actively intervened to relieve the renal artery stenosis, such as surgery or interventional treatment.

The location of the renal artery is quite special, it is behind the peritoneum and very close to the aorta. The main trunk of the renal artery is very short, with an average length of less than four centimeters. In the past, surgeons performed bypass surgery or endarterectomy, but these operations are very, very rare.

Since the advent of intravascular technology, also known as interventional treatment technology, stent implants can solve the problem of narrowed blood vessels. This technology is now very mature and open surgery is basically no longer required.

Figure 2 Original copyright image, no permission to reprint

Only individual patients who are unable to undergo interventional treatment will consider surgical intervention. Currently, endovascular treatment is the preferred treatment for renal artery stenosis.