Renal artery stenting

Overview 

Renal artery stenting is a procedure used to treat blockages in the renal arteries, which are responsible for supplying blood to the kidneys. These blockages, caused by renal artery stenosis, reduce blood flow to the kidneys, affecting their function. By placing a stent to open the blocked artery, the procedure helps restore normal blood circulation, allowing the kidneys to perform their crucial role in regulating the body’s salt and fluid balance. 

When the kidneys are deprived of sufficient blood flow, they are unable to effectively filter the blood and remove excess salt and water from the body, leading to fluid retention. The kidneys also release renin, a hormone that controls salt retention and blood vessel stiffness. With reduced blood flow due to a narrowed renal artery, the kidneys falsely sense low blood pressure and release more renin, which raises blood pressure, even if it is already high. 

This condition is known as renal hypertension, a type of high blood pressure that can strain the heart and other organs. Left untreated, renal hypertension can lead to serious complications, including kidney failure, as the kidneys lose their ability to function properly over time. Stenting the renal artery helps to reduce the risks associated with this condition by improving blood flow and lowering blood pressure. 

Reasons for undergoing the procedure  

A healthcare provider may insert stents in one or both of your renal arteries if there’s a significant blockage that requires treatment. These renal stents help prevent further damage to your kidneys. However, not every blockage in the renal artery requires stenting. 

You may need a kidney stent if you have atherosclerosis (plaque buildup in your artery) causing a blockage greater than 60%, and if this condition cannot be managed with medication alone. You might also be a good candidate for renal artery stenting if your blood pressure remains uncontrolled despite taking high doses of three or more medications. 

In recent years, healthcare providers have performed renal artery stenting less frequently. This is due to several large trials showing no significant benefits from the procedure. However, it’s important to note that these trials excluded patients who may benefit the most, such as those who have: 

• A blockage of 60% or greater in both renal arteries. 
• A single renal artery with a blockage greater than 60%. 
• Flash pulmonary edema (sudden fluid buildup in the lungs). 
• Blood pressure that cannot be managed with three or more medications. 

Risk  

The risks associated with renal artery stenting include:  

• Bruising at the site where the sheath and catheter are inserted.  
• Bleeding at or around the insertion site.  
• Damage to the renal artery or kidney.  
• Blood clots that may form during or after the procedure.  
• Allergic reactions to the contrast dye used in imaging.  
• Stent misplacement or improper positioning.  
• Kidney failure as a potential complication.  

Before the procedure  

Before undergoing renal artery stenting, you will have a consultation with your healthcare provider to assess your overall health and vital signs, including temperature, pulse, and blood pressure. They will also conduct various tests to determine if renal artery stenting is appropriate for you. These tests may include:  

• Duplex doppler ultrasonography: This test uses sound waves to evaluate the size of the blockage and measure the speed of blood flow within your renal arteries.  
• Computed tomography angiogram (CTA): A CT scan, combined with contrast dye, creates detailed 3D images of your kidneys and highlights the renal arteries.  
• Magnetic resonance angiogram (MRA): Similar to an MRI, an MRA uses a magnetic field and radio waves to produce detailed images of your blood vessels, enhanced by contrast dye injected into your bloodstream.  
• Angiogram: This procedure involves inserting a catheter through your groin into the aorta, advancing it to your renal arteries, and injecting contrast dye to visualize blood flow and detect blockages.  

Inform your healthcare provider about all medications you are taking, including prescription, over-the-counter, and herbal supplements. Some medications, such as aspirin, anti-inflammatory drugs, and blood thinners, can increase the risk of bleeding, so consult your provider before discontinuing any medication. 

Additionally, disclose any allergies you have, including reactions to medications, skin cleansers like iodine or isopropyl alcohol, latex, and foods. Your healthcare provider will also provide specific instructions regarding eating and drinking before your procedure.    

During the procedure  

Renal artery stenting is performed during an angiogram procedure. Here’s a general outline of how the process works:  

• Your healthcare provider begins by making a small incision, typically less than an eighth of an inch, in your groin or arm. Through this incision, they insert a hollow tube known as a sheath into the artery. A second hollow tube, called a catheter, is then threaded through the sheath and guided to the affected renal artery.  
• Upon reaching the blocked area of the renal artery, the healthcare provider may use a balloon to inflate and open up the blockage. This creates space for the stent, which is a fine mesh metal tube. The stent is positioned across the blockage and deployed, pressing against the artery wall to push the blockage aside and expand the channel for improved blood flow to the kidney. The stent remains in place to keep the artery open.  
• After positioning the stent, the provider will deflate the balloon catheter, carefully remove it, and apply pressure to the incision site or use a specialized device to seal the artery opening. Finally, a bandage is applied to the incision site.  

After the procedure  

After undergoing renal artery stenting, you’ll typically spend a few hours recovering in the hospital, and in some cases, you may need to stay overnight. During this time, healthcare providers will monitor your overall condition, manage any pain, and keep an eye on your blood pressure. They may also make adjustments to your medications and will discuss these changes with you before your discharge. 

Once your healthcare team determines that you’re stable and no longer need continuous monitoring, they will discharge you. You will need to arrange for a family member or friend to drive you home.    

Outcome  

Renal artery stenting offers several benefits:  

• It’s a minimally invasive procedure with minimal risk of complications.  
• It improves blood flow through the affected renal arteries.  
• It may help lower blood pressure.  
• It can aid in preserving kidney function.  

Most people experience improvement within a few days after the stent placement. Your healthcare provider will advise on the level of activity you should maintain during your initial recovery period.  

You might need to take blood-thinning medications, such as aspirin or clopidogrel, to ensure proper blood flow and prevent clots until the stent area heals. The duration for taking these medications can vary, ranging from one month to a year, depending on your risk of bleeding. It’s crucial to follow your provider’s instructions and not discontinue these medications without consulting them first. Typically, you can resume work or school within a week. However, if your job involves heavy lifting or strenuous activity, you might need additional time off. Follow-up appointments are essential, as new blockages or restenosis can occur, necessitating ongoing monitoring by your healthcare provider.  

Contact your healthcare provider if you experience any of the following: 

• Fever 
• Difficulty breathing 
• Rash 
• Discoloration, swelling, pain, or oozing blood at the catheter insertion site 
• Pain, coldness, paleness, or weakness in the leg where the catheter was inserted 
• New or worsening abdominal pain, especially on the treated side 
• Lightheadedness or a significant drop in blood pressure (hypotension)