Renal artery aneurysm - causes, symptoms, diagnosis and treatment

A renal artery aneurysm is a protrusion of the renal vessel wall. It can be true and false. Clinically, it does not manifest itself in any way at the early stages, later pain in the lumbar region and symptoms of general intoxication appear, the functions of the urinary system are disrupted. Pathology can be complicated by necrosis, infectious processes, internal bleeding. The diagnosis is established based on the data of instrumental methods: ultrasound, angiography, radiography. Treatment is mainly surgical with the removal of an arterial defect. With the formation of massive necrotic or purulent foci, nephrectomy is indicated.

General information

Aneurysm of the renal artery is a local expansion of the vessel by two or more times compared to its normal diameter. The disease is extremely rare in clinical practice. This is partly due to the fact that in most patients the pathology is asymptomatic or with scant manifestations, which complicates statistical analysis. The prevalence among all aneurysms is 0.1-0.15%. In 80% of patients, protrusion of the renal artery wall is combined with renal hypertension. There are no definite patterns between the presence of the disease and the sex or age of the patients. In women, the risk of developing an aneurysm increases during pregnancy, when hormonal changes can affect the elastic properties of the vessel walls.

Reasons

The immediate cause of the formation of protrusion is a violation of the structural integrity of the vascular wall, which occurs in response to the effects of damaging agents. Factors that increase the likelihood of aneurysm formation are considered to be old age, poor nutrition, bad habits, metabolic disorders in diabetes mellitus. The main etiofactors of the occurrence of defects are:

• Atherosclerosis. Violation of the balance of transport and utilization of lipoproteins in the systemic bloodstream leads to atherogenesis with damage to the intima of the vessels. Fatty acids permeate the inner layer of the artery, causing proliferation, cell death, and transformation of the intercellular substance. Migration of leukocytes into the lesion causes an inflammatory reaction. Pathological processes together cause a decrease in the elastic strength of the wall, especially when atherosclerosis is combined with arterial hypertension.
• Infectious diseases. They provoke the start of the development of a mycotic (secondary infectious) aneurysm. The bacterial process in the vessel wall causes inflammatory and immune responses that potentiate the dissolution of elastic structures of the renal artery, increase the risk of aneurysms. The most common infections complicated by vascular protrusions are syphilis, tuberculosis, suppuration of atherosclerotic plaque.
• Congenital pathologies. An aneurysm may be a consequence of a violation of the intrauterine development of the vascular wall or one of the manifestations of a hereditary disease (Marfan syndrome). In both cases, the presence of a defect in the muscular layer of the renal arteries is revealed. Insufficient production of collagen fibers weakens the muscle layer, especially in places of bifurcation, bends.
• Injury of the renal artery. It is usually found in the anamnesis in patients with a false aneurysm. Injury occurs when a mechanical factor affects the renal vessels - open, with knife and gunshot wounds, or closed. Invasive medical interventions with the introduction of probes, catheters, stands into the lumen of the vessel are singled out separately.

Pathogenesis

The basis of the mechanism of aneurysm development is the loss of elastic properties of the medial layer of the renal artery wall, leading to its inability to resist blood pressure. Structural disorders can be congenital (with Marfan syndrome) or acquired (with atherosclerosis, arteritis, infectious diseases). Initially, the inner layer of the vessel breaks while preserving the integrity of the remaining layers. The blood enters the formed defect, under its pressure, a longitudinal stratification of the classical baggy shape is gradually formed at the site of the local lesion. With diffuse circular damage to the artery, the protrusion has a fusiform shape. With false aneurysms, the site of the vessel expansion is formed from connective tissue without the participation of the muscle layer.

The immediate collapse of the aneurysm leads to massive bleeding. Microfractures can be thrombosed, after which a retroperitoneal hematoma is formed with subsequent encapsulation. When an infection enters the hematoma area, suppuration of adipose tissue occurs, without medical help, the risk of sepsis is high. Compression of the renal calyx-pelvic system by protrusion of a large size worsens the passage of urine, provokes stagnation, which increases the likelihood of pyelonephritis.

Classification

The division of renal vascular aneurysms into separate types is based on the features of their location, causes, and pathogenesis. By localization, there are protrusions of the actual trunk of the renal artery and its small branches, by etiology - congenital, atherosclerotic, inflammatory, post-traumatic lesions and aneurysms that have arisen as a result of medical manipulations. The most important from a clinical point of view is the classification according to the structure of the vessel wall in the expansion zone:

• True. They are more common in the area of the main artery or its middle branches, reaching a diameter of 10 cm. This type of aneurysm is combined with structural changes in the vascular wall, especially against the background of atherosclerosis or congenital anomalies of elastic components. Extrarenal localization is characteristic. Multiple true aneurysms in the form of a "string of beads" with a low risk of rupture are possible.
• False. They are a complication of blunt or penetrating injuries of the lumbar region, accompanied by injury to the vessels of the kidneys. They are diagnosed immediately after receiving damage or in a short period after it (1-2 days). Another variant of development is iatrogenic, as a result of medical endovascular manipulations in the lumen of the renal artery.

Symptoms

An aneurysm of small size proceeds for a long time without clinical manifestations. The detection of pathology is possible with a routine examination of the kidneys by instrumental methods or the diagnosis of other diseases. Gradually, the aneurysm increases, begins to put pressure on the surrounding organs, tissues. The patient has a feeling of bursting, pulling pain in the lower back on the side of the lesion.

When the protrusion is located in the kidney, the ureter is compressed, which significantly impairs the functioning of the organ. This can lead to the development of kidney failure, kidney infarction. Clinically, this disorder is manifested by symptoms of intoxication: nausea, vomiting, weakness, headache, dizziness. With the baggy form of an aneurysm, the risk of blood clots with subsequent necrosis of the renal tissue is especially high. The necrosis that has begun causes intense pain, which is given to the lower abdomen, genitals, hip. The general condition of the patient is rapidly deteriorating.

Rupture of vascular protrusion is considered the most dangerous complication of an aneurysm, leading to shock and death in 70% of cases. Signs of internal bleeding are sharp pain in the lower back, abdomen, which increases with any physical exertion, weakness, pallor of the mucous membranes and skin, dry mouth, shortness of breath, tachycardia, headaches, a sharp decrease in blood pressure. A patient with such symptoms needs immediate surgical care.

Complications

The formation of an aneurysm in an arterial vessel of significant diameter is always considered a life-threatening condition due to a possible rupture and the development of massive intracavitary bleeding. The loss of 0.5 liters at the initial stages is practically not clinically manifested, with the loss of 2 liters, hypovolemic shock and death of the patient may occur. With a protrusion size of 8-10 cm, the time interval between these two volumes of blood is calculated in minutes. There is a high risk of developing pyelonephritis, especially in the presence of hydronephrosis. The formation of retroperitoneal hematomas can be complicated by suppuration and the formation of abscesses. The appearance of a zone of turbulent blood flow in the place of protrusion becomes a predisposing factor of thrombosis. A blood clot can lead to blockage of the renal artery and a kidney infarction.

Diagnostics

Aneurysm is detected by urologists-nephrologists, vascular surgeons in the presence of appropriate symptoms, is diagnosed using instrumental methods. With small sizes, it can be asymptomatic, it is detected by chance. Physical and laboratory methods are not informative enough at the onset of the disease, they can only indirectly indicate the presence of inflammation or confirm an imbalance of the lipid spectrum. The key diagnostic measures are:

• Physical examination. At the stage of aneurysm formation, it does not provide significant data, it is possible to detect soreness on palpation, a positive symptom of Pasternatsky. This method plays a key role in the early detection of a rupture of the renal artery with massive abdominal bleeding. Examination reveals pallor of the skin, mucous membranes, acrocyanosis, dry tongue, shortness of breath, lethargy, a combination of rapid heart rate and low blood pressure.
• Ultrasound examination. It is able to visualize the state of the renal vessels, the presence of formations pulsating in time with the heart rhythm. The combination of ultrasound with Dopplerography makes it possible to differentiate between an aneurysm and a tumor of a vessel or parotid tissue. The neoplasm is indicated by the presence of its own vessels, a denser structure.
• X-ray examination. Urography is more often performed with the use of a contrast preparation and reveals indirect signs of protrusion of the vascular wall — deformation of the renal pelvis, uneven filling of cups. Possible irregularity of the contours of the kidney, an increase in the organ. With the formation of necrotic foci, an altered parenchymal structure is visible on the X-ray.
• Angiography of the renal arteries. The contrast agent injected with this method of examination allows you to evaluate the vascular network of the organ, determine the localization of the aneurysm with high accuracy, its type, size, confirm or deny bleeding. Kidney angiography makes it possible to clarify the degree of stenosis, the presence of blood clots, thromboembolism.
• Laboratory methods. They become very important for internal bleeding. In the general blood test, anemia is noted – a decrease in the total amount of hemoglobin, peripheral blood erythrocytes. Due to the loss of red blood cells, hematocrit decreases. The changes in the coagulogram are non-specific.

Treatment of renal artery aneurysm

If pathology is detected in the early stages, when the size of the protrusion does not exceed 0.5-1 cm, and there are no clinical symptoms of the disease, a wait-and-see tactic with dynamic monitoring and monthly ultrasound monitoring is recommended. If during the next appointment the patient shows signs of an aneurysm enlargement, changes in well-being appear, indicating a deterioration in the course of the process, surgical treatment is indicated. The following methods are used:

• Intravascular surgical interventions. They are a priority in the treatment of local extensions of the renal artery, allow to minimize tissue injury, improve the prognosis. Prosthetics of the vessel with the reconstruction of the wall with an autograft, the imposition of a clip-clamp, endovascular strengthening of the defect zone with a high-strength material that prevents the progression of the disease is possible. If it is impossible to restore the normal structure, the artery is "turned off" from the general blood flow, creating new ways of blood movement (bypass surgery).
• Nephrectomy. An extreme measure applied according to strict indications when it is impossible to eliminate pathology and its complications by minimally invasive methods. It consists in the complete removal of the affected kidney by open or mini-access. Kidney infarction, severe purulent processes with massive irreversible damage to the renal parenchyma are considered as indications for surgery.

After surgery, a course of antibiotic therapy with broad-spectrum drugs is indicated. Additionally, physiotherapy is prescribed - UHF, magnetic therapy. The duration of the recovery period depends on the volume of the intervention, with endovascular operations to strengthen the vascular wall is about 7 days, after bypass surgery up to 1 month, after nephrectomy - up to 2 months. A gentle diet is recommended with a restriction of salt to 2 g per day, liquids up to 1-1.5 liters, with the exception of fatty dishes.

Prognosis and prevention

With timely detection of a renal artery aneurysm, properly performed surgical intervention, the prognosis is favorable. The risk of relapse depends on the etiology of the process, the therapy of diseases that served as triggering factors for the formation of a vessel defect. Since the most common cause of loss of elastic properties of the vascular wall is atherosclerosis, prevention is aimed at preventing and correcting metabolic disorders. Patients should adhere to a diet low in salt and fat, plenty of vegetables and fruits, take anti-atherosclerotic drugs.