The kidney is an important organ in the human body, its most important role is to excrete some metabolic wastes in the blood through urine, in addition to regulating the body’s endocrine, hematopoietic and blood pressure. The renal artery is a very important blood vessel that directly divides from the trunk aorta, supplying blood to the kidneys, and is an important way to feed and maintain the kidneys. Therefore, the narrowing or occlusion of the renal artery will have a great impact on the function of the kidney.
First of all, patients will suffer from hypertension due to renal artery stenosis, which is medically called renal hypertension, sometimes called malignant or intractable hypertension. This type of hypertension is often as high as 180, 190 or even 200 mmHg or more, and is difficult to control with medication. Subsequently, patients will suffer from gradual narrowing or occlusion of blood vessels, resulting in the function of the entire kidney being affected, elevated blood creatinine, and even kidney atrophy.
I. Why do you suffer from renal artery stenosis?
Renal artery stenosis can occur in people of all ages, with middle-aged and elderly people being the most common. Among them, renal artery stenosis in middle-aged and elderly people is mostly caused by atherosclerosis, while renal artery stenosis in young people is mostly caused by aortitis or myofibrillar dysplasia.
Clinically, renal artery stenosis due to atherosclerosis is more common, and the lesion is characterized by atherosclerotic plaque causing renal artery stenosis or occlusion. Most of these lesions occur at the opening of the renal artery and are relatively limited. In addition to this, young people or children may have narrowing of the renal arteries due to a specific disease called myofibrillar dysplasia in medical terms.
Another disease that causes narrowing of the renal arteries is aortitis, which is mostly seen in young women. In addition, there are many other causes of renal artery stenosis, the most common clinically is the stenosis caused by atherosclerotic plaque.
Second, what are the risks of renal artery stenosis to the human body?
Mild renal artery stenosis is not enough to cause kidney function hazards. When the stenosis becomes severe, generally greater than 70%, it will cause a reduction in blood flow to the kidneys, and kidney function will be affected. The more severe the stenosis, the greater this effect will be and the greater the threat to the kidneys.
In addition, when the renal artery stenosis reaches a certain level, the kidney will be ischemic, causing the kidney to produce a substance that causes a reflex increase in the patient’s blood pressure, medically called changes in the renal angiotensin-aldosterone system, resulting in a state of hypertension that is difficult to control with medication in severe cases. In clinical practice, we call this renal hypertension.
Therefore, renal artery stenosis has two main dangers: one is the effect on the kidney function itself; the other is renal hypertension.
There have been clinical cases in which some elderly people usually have hypertension, diabetes and atherosclerosis, but they do not pay attention to the examination of the blood vessels of the whole body. The kidney artery stenosis was not discovered in time, and suddenly for a period of time, the blood pressure showed signs of malignancy, which could not be controlled even by taking antihypertensive drugs. The checkups were only about blood tests and liver function, but the examination of blood vessels was neglected, resulting in serious damage to the kidney function. The narrowing of blood vessels became more and more serious, and the kidneys also atrophied, and finally uremia appeared.
Third, what tests can help to confirm the diagnosis of renal artery stenosis?
In addition to clinical symptoms such as hypertension and changes in kidney function that can prompt us to think about the possibility of renal artery stenosis, many cases do not have any symptoms in the early stages of the disease, and are sometimes found to have renal artery plaque or stenosis during a physical examination. So what tests are available to help detect or confirm the diagnosis of renal artery stenosis?
First, renal artery ultrasound, which is convenient, non-invasive and accurate. An experienced ultrasonographer can determine the degree of stenosis of the renal arteries, the location of the stenosis, the blood flow rate at the stenosis site, and the size of the kidney more precisely.
Second, CT angiography, commonly known as CTA, this test requires the use of an angiographic contrast agent.
It is damaging to the kidneys, so drinking a lot of water and urinating more often in the hours before and after the test will help to excrete the contrast agent from the body as soon as possible, thus reducing the damage to the kidneys from the contrast agent.
Third, nuclear magnetic, nuclear magnetic angiography is also a better examination method, but the contrast agent of nuclear magnetic also has certain damage to the kidneys and should also be alert.
Fourth, arteriography, arteriography is a damaging test that requires arterial puncture and cannulation, which needs to be done under the supervision of an X-ray machine and also requires contrast agent, so this method is not used as a preliminary test and is generally only used when the patient is ready for balloon dilation or during stent placement surgery.
Fourth, how to treat renal artery stenosis?
Renal artery stenosis, in terms of treatment, can be divided into two categories.
One type is the surgical intervention approach, which is the adoption of surgical procedures or endovascular interventions (balloon dilation or stent implantation).
In the other category, there is the conservative treatment with medications.
At present, it is considered that surgical intervention is required when the degree of renal artery stenosis reaches 70% or more. Otherwise, further increase in the degree of stenosis will certainly seriously affect the renal blood supply, leading to impairment of renal function and causing severe hypertension, etc. If the degree of renal artery stenosis is relatively mild, with less than 70% stenosis, and the renal blood flow is not greatly affected, it can be closely observed and controlled by taking medications.
The main cause of renal artery stenosis is atherosclerosis, so in the treatment, we also need to take some drugs to control the progress of atherosclerosis, such as, controlling blood lipids, antiplatelet, etc. At the same time, we need to quit smoking, control high blood pressure, high blood sugar and other risk factors that induce atherosclerosis, eat a healthy and reasonable diet, avoid eating foods or drugs that are harmful to the kidneys, etc.
There are two main types of surgical treatment for renal artery stenosis, one is minimally invasive endovascular treatment, which is commonly known as renal artery stenting. The purpose of placing a stent is to prop up the stenosis by a special alloy stent to restore effective blood flow to the kidney and achieve the goal of treating renal artery stenosis. This treatment is minimally invasive and usually involves an arterial puncture in the femoral artery, delivery of the stent to the lesion through a guidewire and catheter, and firm fitting of the stent to support the narrowed renal artery through balloon dilation. The procedure is minimally invasive but technically demanding.
Another type of surgical treatment is surgery. Surgical treatment requires an experienced vascular surgeon. Surgery is a more invasive treatment. It is performed by directly stripping the plaque from the stenotic area of the renal artery or by vascular bypass, with the help of the body’s own veins or artificial vessels, which are grafted to both ends of the stenotic lesion, one end to the aorta and the other to the renal artery. Due to the deep location of the kidney, surgical treatment is more invasive and usually used only when minimally invasive endoluminal treatment is not suitable.
V. What do I need to pay attention to after renal artery stenting?
After renal artery stenting is not a safe deposit box, there are still many issues that need to be paid attention to.
(1) Continue to insist on treatment for the cause, such as treatment of atherosclerosis, aortitis, etc.
(2) Continue to take antiplatelet drugs in addition to medications for the original disease to prevent restenosis and thrombosis of the stent.
(3) Continue to control hypertension and protect the kidneys.
(4) Be sure to review regularly to keep abreast of the patency of the kidney stent and changes in renal function, and to solve problems in time to prevent future problems.
VI. Summary
Renal artery stenosis is a “hidden killer” that causes hypertension and renal function damage, but as long as we understand the characteristics of this “killer”, we can detect renal artery stenosis early and treat it in time to protect our kidney function.