Percutaneous Transluminal Angioplasty of the Renal Artery

Introduction

Atherosclerosis is the leading cause of renal artery stenosis in ninety percent of the cases. The narrowing of the renal artery or the blockage of the renal artery is termed renal artery stenosis. Atherosclerosis is the narrowing of the blood vessels due to the deposit of fat, cholesterol, and other materials on the wall of the blood vessel. Fibromuscular dysplasia is the cause of the remaining ten percent of renal artery stenosis cases. Fibromuscular dysplasia is common among young women but rarely advances to renal artery stenosis. The common progression of fibromuscular dysplasia is seen as renovascular hypertension. When the blood flow to the kidneys is compromised, the blood pressure increases by hormonal regulation of the affected kidney. This is called renovascular hypertension.

What Is Renal Artery Stenosis?

The narrowing of one or both renal arteries is termed renal artery stenosis. It is caused by atherosclerosis and fibromuscular dysplasia. Other less common causes include thromboembolic disease (a clot in the blood vessel that hinders the blood flow), arterial dissection(a tear in the lining of the artery), infrarenal aortic aneurysm (a ballooning or a weak spot in the artery below the kidney), vasculitis (an inflammation of the blood vessel), neurofibromatosis (an autoimmune disorder that causes tumors to arise from nerves), etc. Renovascular hypertension is one of the most common aftereffects of renal artery stenosis. Other associated complications can include chronic kidney disease and end-stage renal disease. Renal artery stenosis is usually characterized by severe hypertension that is not manageable by medication.

What Is Percutaneous Transluminal Angioplasty of the Renal Artery?

Percutaneous Transluminal Angioplasty of the renal artery has gained prominence as a peripheral vascular intervention, especially in treating renovascular hypertension. It was in 1964 that Charles Dotter developed percutaneous transluminal angioplasty as a mode of treatment for peripheral vascular atherosclerosis. It was initially developed as a catheter-based procedure. Later, in 1974, Andreas Gruntzig developed a balloon catheter that was soft, flexible, and had a double lumen. This was initially used for coronary angioplasty and revolutionized the percutaneous transluminal angioplasty procedure. Ever since the procedure has been evolving to develop into a versatile and dependable vascular intervention technique. It is used alone or in combination with renal stenting PTA has gained prominence as a treatment of renal artery stenosis, which can cause renovascular hypertension or impair the functions of the kidney.

What Are the Indications for Percutaneous Transluminal Angioplasty of the Renal Artery?

The indications for percutaneous transluminal angioplasty of the renal artery include:

• Sudden onset of renovascular hypertension.

• Renovascular hypertension in a person without a family history of hypertension.

• Renovascular hypertension in a person without other known medical factors.

• Malignant hypertension (sudden increase in blood pressure that can cause organ damage).

• Hypertension refractory to pharmacotherapy (hypertension that is difficult to control in spite of medication).

• The patient is not taking medicines properly.

• Hypertension in a patient with abdominal bruit (abdominal bruit is a swishing sound on auscultation with a stethoscope, suggestive of renal artery stenosis).

• Hypertension in a patient who advances to kidney failure while on captopril.

• Sudden onset of hypertension in a young woman who is not taking any oral contraceptives.

• Progressive impairment of renal function.

• A spike or uncontrollable hypertension.

Other relative indications can include:

• Congestive heart failure.

• Unstable angina (chest pain).

• Renal insufficiency (Impairment of the function of the kidney due to poor blood supply).

• High-grade renal artery stenosis in patients undergoing infrarenal abdominal aortic aneurysm repair.

What Are the Contra-Indications for Percutaneous Transluminal Angioplasty of the Renal Artery?

Contra-indications for percutaneous transluminal angioplasty can include:

• Advanced stage of the disease (creatinine level greater than 3-4 mg/dl or kidney smaller than 8 cm).

• Limited life expectancy.

• Recent history of myocardial infarction, or bleeding disorders.

• Pregnant women.

How Is Percutaneous Transluminal Angioplasty of the Renal Artery Done?

A catheter used in angioplasty has a balloon at its end, which inflates to widen the artery that is narrow. It is a minimally invasive procedure, with the patient awake during the procedure. A contrast dye will be given, which makes the area being imaged stand out. It is not a very painful procedure, though there can be mild discomfort during the procedure.

A very small incision is made in the groin, through which the catheter is inserted. The catheter is directed toward the renal artery using images produced on the computer. A guide wire with a balloon at its tip is placed on the area of stenosis, and the balloon is inflated to remove the blockage or widen the narrow area. If the procedure requires a stent (which is a fine wire mesh), it is then passed through the catheter and pressed on the walls of the artery. The stent is left behind to leave the artery open for blood flow.

Anticoagulants (medicines to thin the blood) might be given for a few days to maintain the blood flow around the area where the stent is placed.

What Are the Risks Associated With the Procedure?

The risks associated usually outweigh the benefits after the procedure is done. However, the patient should be aware of the risks associated with the procedure. The risks associated with a percutaneous transluminal angioplasty can include:

• An allergic reaction to the dye used.

• Infection of the area where the dye is injected.

• Bruising in the area where the catheter is inserted.

• Bleeding at the insertion site.

• Blood clots.

• Damage to the renal artery.

• Very rarely, kidney failure.

• Very rarely, death.

• An extremely less chance of cancer in the area. This can depend on the number of images taken during the procedure.

• Azotemia (accumulation of urea and other nitrogen-containing substances in the body).

• Cholesterol emboli.

• Restenosis.

• Occlusion of the renal artery.

• Very rarely, dissection of the renal artery(laceration in the artery).

Conclusion

The prognosis after the procedure is excellent if the patient selection is apt and experienced hands perform the procedure. The procedure is widely used and is still developing to be a versatile and dependable vascular intervention technique. Review visits after the procedure should be strictly adhered to prevent complications and to diagnose and treat the complications (if any) at the earliest.