Renal Aneurysm - Causes, Diagnosis, and Treatment

What Is a Renal Artery?

The renal artery is the artery of the kidneys as it carries the blood from the heart to the kidneys. The kidneys are the organs that filter the blood and remove toxins. A human has two renal arteries, the right, and the left. The right renal artery transports blood to the right kidney, whereas the left renal artery carries blood to the left kidney. The renal arteries form an integral part of the circulatory system as they carry a huge amount of blood from the aorta to the kidneys. In simple terms, approximately more than half a cup of blood passes through the kidneys from the renal artery every minute. Normally, healthy kidneys filter 150 quarts of blood daily.

What Is a Renal Artery Aneurysm?

The balloon or bulge formed in the renal artery wall is the renal artery aneurysm. No symptoms are associated with renal artery aneurysms because they are incidentally discovered during radiological examinations of other medical conditions. It might be present congenitally due to the weakness in the walls of the arteries or acquired during an individual's lifetime. It can also occur due to trauma, infection, and other injuries. A renal aneurysm is mostly small and requires no major treatment or surgical intervention. However, the problem arises when the renal aneurysm is large and might rupture the arteries. Surgical intervention might be required to repair the defect in such a situation.

Where Is the Renal Artery Located, and What Are Its Branches?

The renal arteries are paired, meaning each is connected to their respective kidneys to carry blood. A renal artery is about half to two inches long and initiates at the abdominal aorta. It is a branch of the aorta that supplies the vessel in the abdomen. The renal artery enters the kidney and lies at a specific site known as the hilum. The hilum is nothing but the entry and exit point of small nerves and vessels that supply the kidneys. The branches of the renal artery supply the following structures:

1. Nephrons - The renal artery supplies blood to the small filtration units in the kidney known as the nephrons.

2. Glomeruli - The network of tiny blood vessels known as the glomerulus is present in each nephron. It allows water and toxins to move into the tubules known as the nephrons. The proteins and other blood cells remain in the glomeruli.

3. Tubules - As the tubules filter blood and remove the waste, the blood vessels near the tubules reabsorb the filtered fluid along with other nutrients and fluids.

4. Renal Veins - The filtered blood exits the kidneys through the renal vein to circulate through the body.

What Are the Causes of Renal Artery Aneurysms?

Nothing has been known about the exact cause of renal artery aneurysms. However, studies report that hardening of the arterial walls results in degeneration and atherosclerosis, leading to aneurysms. It might also be related to a condition known as fibromuscular dysplasia, a disease wherein the arteries become narrow. Females between the age of 40 to 60 are more likely to experience these conditions. Some risk factors for renal artery aneurysms are pregnancy, polyarteritis nodosa, or the large size of the aneurysm. Patients suffering from these conditions must be considered for surgery as any delay might exacerbate their condition. Studies also report that renal artery aneurysms might also develop due to the following conditions:

1. Chronic and untreated high blood pressure or hypertension.

2. Blunt or penetrating trauma.

3. Radiation or recent surgery.

A computed tomography scan might evaluate patients with hypertension, blood in the urine, and pain in the upper abdomen or sides. The scan provides the best view of the aneurysm and its arteries.

What Are the Signs and Symptoms of a Renal Artery Aneurysm?

Usually, the patient remains asymptomatic for prolonged periods in renal artery aneurysms. However, large renal artery aneurysms might cause hypertension, flank pain (pain in the sides), and decreased kidney function. In addition, some patients might experience hematuria (blood in the urine). If the aneurysm ruptures, it can lead to blood loss, death, and kidney failure.

How Is a Renal Artery Aneurysm Diagnosed?

There are no specific tests to diagnose renal artery aneurysm as it does not produce any major signs or symptoms. Most of them are incidentally diagnosed while other medical conditions are being investigated. Renal duplex ultrasound is also done to diagnose renal artery aneurysms. Duplex ultrasound is similar to a normal ultrasound, the only difference being that the former allows the doctor to visualize the structure of the arteries. In contrast, the latter only provides images of the organs.

How Is a Renal Artery Aneurysm Treated?

The treatment of renal artery aneurysm is recommended for patients with refractory medical hypertension, renal artery stenosis (narrowing of the arteries), or other symptoms related to the aneurysm. Surgical repair should be considered when the aneurysm is more than 3 centimeters, grows rapidly, and affects a woman of childbearing age. A renal artery aneurysm can be repaired by open surgery or endovascular repair. The minimally invasive procedure inside the blood vessels is an endovascular repair procedure. The advantage of endovascular repair surgery over open surgery is that there is a lower risk of major adverse effects and a shorter recovery time. 98 % of aneurysms occur outside the kidneys. However, open surgery is the standard gold repair method if the aneurysm affects more than one artery branch.

What Can Be Expected in Renal Artery Aneurysm Repair Surgery?

The renal artery aneurysm is treated with endovascular repair. In that case, the patient can be expected to stay in the hospital for a day and return to his normal activities within a week. However, the patient might need to stay in the hospital for three to five days if an open surgery is done. Sometimes, the doctor might not operate on the smaller aneurysms and ask the patient to wait for a few days. Dissection can also be done for larger aneurysms.

How Can a Patient Protect the Renal Artery?

The patient need not be worried about the renal artery aneurysm if the blockage is less than 60 %. This is because they can be treated with the following lifestyle and dietary modifications:

• The patient must consume a healthy diet free from fats, cholesterol, salt, and sugar.

• Exercise regularly to maintain a healthy body weight.

• Patients with kidney disease must limit the consumption of potassium and proteins.

• The patient must control his diabetes, blood pressure, and cholesterol levels.

• Avoid smoking and tobacco consumption.

Conclusion:

Renal artery aneurysm typically affects the arteries that supply the blood to and away from the kidneys. It usually affects elderly females but can occur in males, also. The patient might remain unaware of the condition for prolonged periods as they do not experience any symptoms. However, the patient need not worry and seek medical attention at the earliest to learn more about the management of renal artery aneurysms.