Renal artery dissection is a serious condition that affects the blood supply to the kidneys. It occurs when a tear develops in the inner lining of one of the renal arteries, which are the blood vessels that deliver oxygenated blood to the kidneys. This tear allows blood to flow between the layers of the artery wall, potentially reducing or blocking blood flow to the kidney. When blood flow is compromised, it can significantly impact the kidney’s ability to filter waste and regulate blood pressure.
Understanding Renal Artery Dissection
The kidneys receive their blood supply directly from the abdominal aorta, the body’s largest artery, via the renal arteries. Typically, there is one renal artery for each kidney, originating around the L1-L2 vertebral level.
A dissection begins with a tear in the innermost layer of the artery, known as the intima. Blood then pushes through this tear, creating a new channel, or “false lumen,” within the artery wall. This false lumen can expand, compressing the true lumen and thereby restricting blood flow to the kidney.
Renal artery dissections can occur spontaneously or be traumatic. Traumatic dissections often result from injuries such as falls or motor vehicle accidents, where forces cause damage to the renal artery. Spontaneous dissections, however, are often linked to underlying conditions that weaken the arterial wall.
Causes and Risk Factors
Several factors can contribute to the development of renal artery dissection. Fibromuscular dysplasia (FMD) is a non-inflammatory condition where the artery walls develop abnormally, leading to areas of narrowing and enlargement that can predispose to dissection. Atherosclerosis, commonly known as hardening of the arteries, involves the buildup of fatty plaques that can weaken vessel walls and is another frequent cause.
High blood pressure, or hypertension, is a risk factor, as it places increased stress on arterial walls. Certain connective tissue disorders, such as Marfan syndrome and Ehlers-Danlos syndrome, weaken blood vessels, making them more susceptible to tears. Vasculitis, inflammation of blood vessels, can also increase the risk. Pregnancy, especially in those with underlying connective tissue disorders, has been associated with an elevated risk of vascular dissection, including in the renal arteries. Additionally, blunt trauma to the abdomen or back can directly injure the renal artery, leading to dissection.
Recognizing Symptoms
The symptoms of renal artery dissection can vary. Acute presentations include sudden, severe pain in the flank (side) or abdomen, which may radiate to the epigastrium. This pain is frequently accompanied by a sudden onset or worsening of high blood pressure.
Other acute indicators are nausea, vomiting, and the presence of blood in the urine, known as hematuria. In cases where the dissection develops more slowly, symptoms might be subtle or chronic. These can manifest as persistent high blood pressure that is difficult to control with medication, or a gradual decline in kidney function. Some individuals may even remain asymptomatic, with the dissection being discovered incidentally during imaging for other conditions.
Diagnosis and Treatment
Diagnosis
Diagnosis involves imaging tests and blood work. Imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Angiography (MRA), and Doppler ultrasound are used to visualize the renal arteries and detect tears or blockages. CTA provides detailed cross-sectional images with contrast dye, MRA uses magnetic fields for vessel imaging, and Doppler ultrasound assesses blood flow. Conventional angiography, an invasive procedure, is considered the gold standard for definitive diagnosis, offering precise visualization and allowing for pressure measurements. Blood tests, such as kidney function tests (e.g., serum creatinine and urea nitrogen) and lactate dehydrogenase (LDH) levels, can indicate kidney damage or infarction.
Treatment
Treatment approaches depend on the severity of the dissection and the patient’s overall condition. Medical management involves controlling blood pressure with antihypertensive medications and managing pain. Anticoagulation therapy, using medications like warfarin or aspirin, may be prescribed to prevent blood clot formation within the dissected artery. Patients with uncontrolled hypertension or declining kidney function may require more aggressive interventions.
Interventional procedures, such as angioplasty and stenting, are minimally invasive options. During angioplasty, a balloon is inflated to widen the narrowed artery, and a stent—a small mesh tube—may then be placed to keep the artery open and stabilize the tear. This approach is preferred for atherosclerotic lesions or dissection flaps. In more complex or severe cases, surgical repair may be necessary. Bypass surgery involves grafting a healthy blood vessel, often from the patient’s leg or a synthetic tube, to create a new pathway for blood to flow around the dissected segment, restoring blood supply to the kidney.
Potential Complications
If not properly managed, renal artery dissection can lead to several complications. Uncontrolled hypertension, sometimes referred to as renovascular hypertension, is a common complication, as restricted blood flow to the kidney can trigger hormonal responses that elevate systemic blood pressure. This persistent high blood pressure can further damage the kidneys and other organs.
Acute kidney injury can develop rapidly if blood flow to the affected kidney is severely compromised or completely blocked. Over time, chronic kidney disease may ensue, potentially progressing to end-stage renal disease if both kidneys are affected or the damage is extensive. Reduced blood supply can also lead to kidney atrophy, where the affected kidney shrinks due to lack of nourishment. In some severe instances, complete loss of function in the affected kidney may occur. The dissection may also extend to other arteries.