Introduction
An aneurysm is ballooning the artery at its weakest point in the artery wall. An aneurysm's wall can be so thin that it can rupture easily. An aneurysm that has ruptured can cause internal bleeding and stroke. Sometimes, it can be fatal or life-threatening. A false aneurysm at the weakest point or an injured spot of the artery wall is called a pseudoaneurysm. A pseudoaneurysm may not involve all the artery wall layers and can be found between the layers.
What Are Renal Artery Pseudoaneurysms?
Renal artery pseudoaneurysm is a rare vascular lesion. When the renal artery enlarges more than twice its normal diameter, it is called a renal artery aneurysm. It usually occurs following a surgical procedure in the kidney like a partial nephrectomy (a procedure where the surgeon removes the damaged tissues, leaving behind the healthy tissues) or percutaneous nephrostomy (inserting a small thin tube through the skin into the kidney to drain the urine).
How Was Renal Artery Pseudoaneurysm Discovered?
Published the first report on renal artery aneurysms in 1770 by Rouppe. It was associated with the death of a sailor who fell onto his right flank. Large false aneurysms were discovered on autopsy. In most cases, aneurysms in the renal artery were discovered while treating for some other condition as they remain asymptomatic.
What Is the Pathophysiology Behind Renal Artery Pseudoaneurysm?
Renal artery aneurysm can be formed as a surgical procedure complication like a partial nephrectomy. It can cause complications in a kidney transplant procedure. Very rarely, renal artery pseudoaneurysms can cause infections. The pseudoaneurysm in the renal artery differs from a true aneurysm in the renal artery. A pseudoaneurysm might not involve all the layers of the arterial wall. The weakening and ballooning occur in all the layers of a true aneurysm.
In fibrous dysplasia, the degenerative changes weaken some parts of the artery, leading to the condition. This can also be associated with stenosis or narrowing of the renal artery. The aneurysm is usually found at the bifurcation of the artery in such cases. Ehlers-Danlos syndrome is when medium-sized and larger arteries become fragile due to pro-collagen deficiency. (Pro-collagen helps to maintain the elasticity of the arteries). It is an autosomal dominant condition. The anastomotic leaks after surgery to the area can cause the blood to collect in the form of a saccular pouch at the weak area.
What Are the Causes of Renal Artery Pseudoaneurysms?
A pseudoaneurysm can be extra-parenchymal(not related to the functional tissues of an organ) or intra-parenchymal (related to the functional tissues of the organ). Its causes can include;
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Blunt Abdominal Trauma: This usually occurs due to a motor vehicle accident, assault, or falls.
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Anastomotic Areas: An anastomotic area is where two artery branches meet. Weakening of this area can cause the formation of pseudoaneurysms.
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Iatrogenic Injuries During Endovascular Procedures: Small injuries or perforations during endovascular procedures can cause the weakening of certain areas in the blood vessel, causing a pseudoaneurysm.
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Spontaneous: Sometimes pseudoaneurysms arise independently due to certain weak spots in the arterial wall.
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Dissection: Dissection, if deeper than required, can weaken the blood vessel wall, giving a high risk to the formation of pseudoaneurysms.
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Mycotic: These are aneurysms associated with bacterial, fungal, or viral infections.
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Kawasaki Disease: It is a condition that causes inflammation of the arteries. This can cause weakening of the blood vessels, leading to the formation of pseudoaneurysms.
What Are the Signs and Symptoms Associated With Renal Artery Pseudoaneurysm?
Renal artery aneurysms remain asymptomatic in most cases. Hence it is not easily diagnosed in most cases. It is accidentally diagnosed while checking for some other conditions in the abdominal region. The symptoms that are observed commonly in symptomatic patients can include;
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Increased blood pressure (hypertension is the most common symptom in ninety percent of cases where renal artery pseudoaneurysm is symptomatic).
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Pain in the abdominal region.
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Hematuria (the presence of blood in urine).
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Rarely rupture of the aneurysm.
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If the aneurysm ruptures, it can be fatal and cause death.
How Is Renal Artery Pseudoaneurysm Diagnosed?
The following studies should be performed before any surgical intervention for a renal artery aneurysm:
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Complete Blood Count (CBC): A complete blood count is necessary before any surgical procedure.
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Chemistry Panel: They include a group of tests done routinely to determine a person's general health status. They help evaluate the organs' functioning properly (like the body's electrolyte balance tests). The tests are usually performed on a blood sample. Blood urea nitrogen (BUN) and creatinine levels must be checked to determine whether the kidneys function correctly.
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Coagulation Profile: They help to understand if a wound formed will heal properly and the possibility of ant clot formation.
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Urinalysis: This is another test to evaluate the body's functioning through a urine sample.
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Ultrasonography: The least invasive imaging study that can be done is ultrasonography (US) with duplex examination. The duplex examination uses the Doppler-shift measurement to find the direction and velocity of blood flow. This is useful for identifying renal artery stenosis also. The US can also determine how functional a kidney is by measuring its size. (Doppler shift is the change in frequency of a wave measured by an observer moving relative to the source of the wave).
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Computed Tomography (CT): CT is the test of choice for diagnosis and follow-up of renal artery pseudoaneurysm. Its anatomic resolution is superior to that of the ultrasound tests.
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Magnetic Resonance Angiography (MRA): This procedure produces images similar in quality to those obtained with arteriography (a procedure like an X-ray used to visualize arteries). However, this technology is neither economical nor as well known as US or CT.
How Is Renal Artery Pseudoaneurysm Managed?
The conditions where medical intervention is required can include;
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Rupture.
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Symptomatic.
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Renal artery pseudoaneurysms pregnant women.
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Diameter greater than two cm.
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Enlarging pseudoaneurysms in the renal artery.
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Renal artery pseudoaneurysm associated with dissection.
Regular review visits with ultrasonography (US) or CT is required in patients who are treated expectantly. The use of robot-assisted laparoscopic approaches is currently being explored. Surgical management of the condition is required if bleeding or rupture occurs.
Conclusion
The condition has low morbidity and mortality rates following elective repair. The prognosis after the rupture has been increasing in the past few decades. However, mortality following a rupture in pregnancy is still high. Studies show that surgical repair appears to have longer-term durability.
