Hypertension is a complex cardiovascular disease. As long as hypertensive patients adhere to medication according to the doctor's advice, their blood pressure can be maintained at a stable level. However, there is a type of hypertension that is resistant to drug treatment, known as renal vascular hypertension or renal artery stenosis hypertension.
Renal vascular hypertension refers to high blood pressure caused by narrowing or occlusion of the renal artery or its major branches due to various reasons, leading to reduced renal blood flow or renal ischemia.
Renal vascular hypertension accounts for 1% to 5% of the hypertensive population. It is mainly caused by reduced renal blood flow due to renal artery stenosis, which can activate the renin-angiotensin system, leading to increased blood pressure and heart failure. Progressive luminal narrowing may cause renal ischemia, resulting in progressive renal parenchymal damage and reduced renal function, leading to renal failure. The incidence rate in asymptomatic individuals is 7%. The prevalence rate in people undergoing vascular imaging for other atherosclerosis is between 28% (coronary angiography patients) and 50% (peripheral vascular angiography patients). The most common cause of death in patients is cardiovascular events. The survival rate of patients also decreases significantly with the progression of atherosclerosis. Data shows that the 4-year follow-up survival rate of patients with renal artery stenosis ≥ 50% found in diagnostic cardiac catheterization patients is 65% compared to 86% in other patients (P <0.001).
The mechanism of renal vascular hypertension is as follows: due to renal artery stenosis or occlusion, renal ischemia or inadequate blood flow can occur, leading to decreased intrarenal pressure, which stimulates the juxtaglomerular cells in the kidneys to secrete large amounts of renin, leading to increased production of angiotensin II and aldosterone. Angiotensin II can cause systemic vasoconstriction, leading to increased blood pressure. On the other hand, increased aldosterone secretion can cause sodium and water retention in the body, which is also a cause of increased blood pressure. Therefore, the narrowing or occlusion of the renal artery is the fundamental cause of renal vascular hypertension. So, how does renal artery stenosis occur? The common causes are mainly two: one is the presence of atherosclerotic plaques in the renal artery, leading to renal artery stenosis. This situation is more common in the elderly. The other is multiple arteritis leading to renal artery stenosis. This situation is more common in people under 30 years old.
The clinical manifestations of renal vascular hypertension mainly include sustained elevation of blood pressure, especially a significant increase in diastolic pressure. In addition, due to high blood pressure, patients may also experience dizziness, headache, chest tightness, palpitations, nausea, vomiting, and decreased vision. In addition, back pain is a common symptom in patients with renal vascular hypertension. Some patients may also experience hematuria and proteinuria. Severe cases can also cause complications such as congestive heart failure, renal insufficiency, and malnutrition. Therefore, early detection and timely symptomatic treatment are important for renal vascular hypertension.
If any of the following conditions occur and antihypertensive medications are ineffective, renal vascular hypertension should be considered: 1) sudden onset of hypertension and rapid progression to accelerated hypertension (also known as malignant hypertension); 2) transition from benign hypertension to accelerated hypertension; 3) hypertension occurring before the age of 30 and the cause is unknown; 4) hypertension occurring after abdominal or lumbar injury or after unexplained abdominal pain; 5) diastolic pressure (lower pressure) is regularly above 100 mmHg, accompanied by decreased vision; 6) frequent unexplained dizziness or vertigo, and vascular murmurs can be heard in the epigastric region, periumbilical region, or costovertebral angle during abdominal examination.
If suspected of having this disease, specific examinations can be performed to assist in diagnosis, such as intravenous pyelography (IVP), radionuclide imaging (ECT), renin activity measurement, duplex ultrasound, spiral CT (computed tomography), magnetic resonance angiography (MRA), and abdominal aorta-renal artery angiography. Among them, abdominal aorta-renal artery angiography is the most valuable examination. This is because this examination can not only observe the abdominal aorta, bilateral renal arteries and their branches, and renal parenchyma, but also determine the location, extent, and degree of vascular stenosis. Renal artery stenosis can cause renal ischemia, and renal ischemia can reduce the production of antihypertensive substances in the kidneys (such as kinins and prostaglandins). On the other hand, hypertension can cause pathological changes in the small arteries of the kidneys, further aggravating renal ischemia, forming a vicious cycle, and causing sustained elevation of blood pressure in patients with renal vascular hypertension. Therefore, for patients with renal vascular hypertension, the use of antihypertensive drugs alone is not effective in treatment. However, once the diagnosis is confirmed, if the stenosis or occlusion of the renal artery can be relieved in a timely manner, the hypertension can be reversed. Currently, surgical treatment is the main approach to treating renal vascular hypertension.
The commonly used surgical methods in clinical practice mainly include abdominal aorta-renal artery bypass, renal artery angioplasty, renal artery endarterectomy, and interventional therapy. The appropriate surgical method can be selected based on the specific condition of the patient. If the above-mentioned surgeries cannot be performed, or if it is determined that the affected kidney has lost normal function but the other kidney has good function, nephrectomy of the affected side can be considered. Surgical treatment can effectively relieve renal ischemia, thereby reducing blood pressure and gradually restoring it to normal.
