What is renovascular hypertension?

Mechanism of occurrence

Why is hypertension called renovascular? The explanation is simple: this word has a Latin origin, the first root (-ren-) means a kidney, and the second (-vas-) is a vessel. Hence, the term itself refers to the vessels passing through the kidneys.

Renovascular hypertension is a characteristic symptom of renal hypertension, a secondary disease against the background of pathological disorders in the renal area. The appearance of such a symptom indicates a violation of the blood supply in these important organs.

Symptomatic hypertension is less common than essential (primary). The secondary disease accounts for about a tenth of all cases. The renal form of hypertension takes up most of them.

Renovascular hypertension results from narrowing of the artery in the kidney. Why does the pressure rise?

1. The fact of narrowing of the vessel provokes a deterioration in the blood supply to the kidneys. The body's response is to increase the production of a special hormone - renin. Its task is to compensate for the decreased blood flow.
2. Under the influence of renin, the peripheral vessels are narrowed in order to increase the blood flow in the large arteries. But compensation does not occur, it is not possible to establish local blood circulation due to the narrow passage in the main artery. Since the desired result has not been achieved, and the production of renin continues, the small vessels are narrowed more and more.
3. The excessive presence of renin in the blood causes an increased activity of angiotensin, which spasms the systemic arteries, increasing blood pressure in the periphery. In addition, angiotensin affects the release of the hormone aldosterone by the adrenal glands.
4. Aldosterone traps sodium in the blood cells of a healthy kidney, which, in turn, interferes with fluid excretion from the body, so urine is not completely excreted. The result is a deterioration in the functioning of the kidneys, the appearance of edema, which also provokes an increase in the resistance to blood flow in the peripheral vessels.

All these processes force the pressure to be kept at a high level for a long time.

Stages of development

Renovascular hypertension can be the result of damage to one or both kidneys. A permanent increase in pressure is characterized as a benign or malignant process.

Benign renovascular hypertension is said to be when the pathology develops gradually, smoothly, without pronounced symptoms. The tonometer readings in this case will change as follows: the systolic level is raised to moderate levels (130-140), while the diastolic level reaches significant high levels (up to 110 inclusive). Dyspnea, general weakness, and chronic fatigue complement the clinical picture.

If we are talking about malignant renovascular hypertension, then in this case, a sharp deterioration in the patient's well-being can be noted. It is manifested by the following symptoms: excruciating headache with bouts of nausea and even vomiting, severe dizziness, decreased vision. The lower pressure rises to 120.

There are three main stages in the development of renal hypertension:

• The stage of full compensation for pathological disorders in the vessels.
• The stage of partial compensation, when signs of renovascular hypertension appear, which are difficult to respond to therapeutic intervention; the damaged organ begins to shrink to a small size, the amount of urine excreted decreases.
• The stage of the absence of effective compensation, the pressure is constantly at a high level, the treatment has no effect, there is significant swelling in the tissues of the organ, the kidney is further reduced in volume and almost does not function.

Renovascular hypertension, characteristic of the last stage, requires urgent measures to eliminate it. Otherwise, the consequences can be the most sad, up to and including death.

Types of pathology

The nature of symptomatic hypertension developing against the background of renal diseases can be of two types: parenchymal and vasorenal.

The first type is noted with damage to the renal parenchyma. The parenchyma of an organ is called the tissue that fills it. The cells of the renal tissue are represented by the medulla and cortex located in the capsule, from all sides they are surrounded by intertwined capillaries. The parenchyma is responsible for the main function - the elimination of urine from the body, and also cleanses the blood from toxic substances.

When inflammation of the renal tissue occurs, diseases such as chronic pyelonephritis, kidney stones, tuberculosis, the formation of renal cysts, hydronephrosis, dystrophic changes caused by organ trauma are diagnosed. The development of hypertension is noted at the stage of an already formed chronic process - renal failure. Such problems arise more often in young people. The increase in pressure is malignant and can lead to impaired brain and cardiac functions.

Renal hypertension is the result of damage to the walls of the renal vessels, which narrow and reduce the passage for blood flow.This happens for various reasons, the most common of which is the occurrence of blood clots or atherosclerotic plaques that block the lumen in the artery.

Causes

The causes of vascular renal hypertension can be the following pathological conditions:

• Atherosclerotic changes in the great vessels.
• Fibromuscular hyperplasia; the proliferation of tissues that make up the structure of the vascular walls, while the muscle layer is replaced by a cicatricial neoplasm; the vessels are narrowed due to the sealing of the walls.
• Takayasu's syndrome (a non-specific form of aortarteritis).
• Panarteritis of the aorta and its branches.
• Renal artery embolism.
• Congenital stenosis of the renal arteries.
• Congenital malformations of the kidney.
• Local clamping of blood vessels by malignant formations, cysts, aneurysms.
• A sclerotic change in a vessel after a cancer tumor is treated with radiation.

Vascular atherosclerosis is one of the main factors causing a persistent increase in renal pressure. Excess cholesterol accumulates on the walls of blood vessels, forming cholesterol plaques, almost halving the lumen at the mouth of an artery or in a nearby area. The development of atherosclerosis can be triggered by an addiction to tobacco products, abundant fatty foods, and the age factor. Men begin to suffer from atherosclerosis earlier than women, around the age of 40.

The origin of fibromuscular hyperplasia (dysplasia) is explained by a congenital predisposition of an unexplained etiology. Hyperplasia is an excessive proliferation of tissues that form an organ. Inflammation of muscle fibers in the vascular wall is accompanied by their growth and transformation into scar tissue. In addition, microaneurysms may appear. The consequence of such changes is the compaction of blood vessels, narrowing of the lumen in them. The aorta takes on a characteristic bead-like appearance: this is how the alternating narrow and widened sections of the vessel look like.

Takayasu's syndrome is associated with genetic disorders and belongs to the group of autoimmune diseases. Distinctive features: the aorta narrows, the inflammatory process can occur from both sides until the opening in the vessel is completely blocked, the pulse in the hands becomes confused or completely absent. The disease affects the inner surface of the aorta and its branches, they thicken due to the formation of granulomas on the walls, aneurysm appears, blood flow is disturbed. Renovascular arterial hypertension occurs against the background of a long course of the pathological process (about 5-6 years).

Panarteritis is a disease caused by inflammatory processes affecting all structural elements of the artery. The cause of this pathology can be infections of various etiologies.

Embolism of the renal arteries is a blockage of a vessel with a thrombotic formation that moves along with the blood. In the appearance of such formations (blood clots), cardiac pathologies are most often to blame. Microtrobms are formed in the tissues of the heart and, breaking off with a sharp intensified contraction, are thrown into the blood. From there, they enter the renal vessels, causing the formation of a secondary thrombus that blocks the passage of blood flow. This phenomenon is accompanied by vasorenal arterial hypertension.

Congenital stenosis of the arteries is a defect formed at birth, characterized by the presence of narrow areas in the vessel. This pathology, like the others, causes circulatory disorders and increased blood pressure.

Congenital malformations of the kidneys include a large number of pathologies, here are some of them: abnormal development of blood vessels, the absence of one kidney or a doubling of one of them, the formation of a third kidney, enlarged or reduced kidney sizes, irregular organ shape or location, the presence of abnormal changes in the structure renal tissue. All these anomalies contribute to the occurrence of renovascular hypertension.

Compression of the renal artery by volumetric neoplasms from the outside: these can be aneurysms, cysts, tumors. As a result of this pressure, the permeability of the vessel decreases, which causes persistent hypertension.

The effects of radiation therapy in the treatment of cancerous tumors can be negative for the blood vessels, causing the formation of scar tissue on the walls and further blockage of the lumen.

Symptoms

The manifestation of renovascular hypertension combines signs of increased blood pressure and concomitant renal disease. The main symptoms include:

• steady uncontrolled pressure increase;
• dizziness, "flies" before the eyes;
• severe pain in the back of the head;
• possible nausea or vomiting;
• clouding of consciousness;
• weakness, loss of strength;
• distracted attention, forgetfulness;
• an increase in diastolic pressure;
• an increase in the volume of the myocardium;
• a sharp painful syndrome in the lumbar region;
• listening to the renal arteries, a characteristic noise can be noted;
• violation of visual function;
• an increase in signs of renal failure;
• the development of severe complications affecting the heart muscle, head could.

Complications of renovascular hypertension

Renovascular hypertension is a dangerous condition, especially a malignant form of pathology. A prolonged increase in pressure entails irreversible changes in the main organs; in an acute course, urgent measures must be taken to assist the patient. Sometimes it’s just minutes. Failure to timely emergency treatment can cost a person his life or lead to disability.

The severe consequences of a sustained rise in pressure include the following:

• damage to the visual organs leading to loss of vision (retinal hemorrhage, retinal detachment);
• acute and chronic heart failure;
• myocardial infarction;
• cerebral hemorrhage, edema and hypoxia of cerebral tissue, leading to a stroke;
• renal failure.

To prevent dangerous conditions, timely diagnosis of the disease is necessary, which serves as a platform for the development of renovascular hypertension.

Diagnostics

To carry out reliable diagnostics, one must have an idea of ​​the clinical manifestations of the disease: does the patient have signs of an acute course of heart failure, manifestations of impaired blood flow in the brain, does he have frequent hypertensive crises.

Next, the doctor turns to laboratory blood tests (they perform an analysis for cholesterol, determine the level of renin, potassium, aldosterone, creatinine) and urine (detect the presence of protein and blood cells).

Among instrumental studies, the following methods are applicable:

• electrocardiogram;
• ultrasonography;
• dopplerography;
• radiography by radioisotope method;
• computed tomography of the kidneys;
• radionuclide urography;
• angiographic method for examining arteries in the kidney area.

The main directions of all ongoing studies are to identify the initial causes of renovascular hypertension and assess the quality of the kidneys.

Treatment

After establishing the exact cause of persistent high blood pressure and determining the nature of the manifestation of this symptom (malignant or benign), one of the possible types of treatment is used. Renovascular hypertension can be treated conservatively or operatively.

If a benign type of pathology is ascertained, drug (conservative) treatment can help the patient. The complex of drugs prescribed in this case:

• diuretics (Furosemide, Hypothiazide);
• alpha and beta blockers;
• calcium channel blockers (Amlodipine, Diltiazem);
• ACE inhibitors and drugs that block angiotensin receptors (Losartan, Irbesartan);
• means for reducing blood viscosity ("Aspirin", "Dipyridamole").

But more often than not, these measures are not enough, they are applicable during the period before the operation or after it.

Surgery is usually recommended when renovascular hypertension is detected. It involves two types of operations: open angioplasty and balloon angioplasty.

Reconstruction of damaged vessels using open-cavity surgery includes the following areas: elimination of the defective area, replacement with a prosthesis. The material for vessel reconstruction is synthetic prostheses and prostheses based on the patient's own veins or arteries.

The essence of balloon angioplasty is to insert a catheter subcutaneously into a damaged artery. There is a silicone balloon at the tip of the catheter. The device reaches the constricted area and is then inflated, after which the balloon inserts a small prosthesis into the artery. This method does not require general anesthesia or large incisions. However, it is not suitable for all cases. If vascular stenosis is observed at the entry point of the artery into the kidney, or an almost complete narrowing of the vascular lumen is found, open surgery is prescribed.

In some cases, removal of the tumor or other formations is required to treat renovascular hypertension. Sometimes one of the kidneys has to be sacrificed.

Thus, there can be many reasons for the appearance of such a syndrome as renovascular arterial hypertension. Identifying them is the first step towards eliminating persistent pressure build-ups. The second step is to fight the disease that caused the development of a dangerous symptom. Early diagnosis and timely treatment will help avoid serious consequences.