Renal Angiogram / Stenting
When your physician recommends intervention as part of your treatment plan he/she is recommending treatment be done using catheters placed through the skin and threaded to the area of blockage or narrowing. A procedure that is done by placing a needle through the skin into a blood vessel is known as a percutaneous procedure. As the catheter is threaded through the blood vessels, the procedure becomes a transluminal procedure (treating from within). This method of treatment is known as a percutaneous transluminal intervention.
What is Stent?
The stent is without question the most exciting invention to appear in cardiology since balloon angioplasty. Over 100,000 patients had these metal coils embedded in their heart the first year the stent was approved for use. Stenting of the Renal Artery may assist in improved blood pressure management, this will be discussed with you by your physician.
Stents come in several designs. Some may look like a small metal coil, some like a slotted tube, and others appear more like a mesh tube. A stent is very tiny. It is usually less than an inch in length, as narrow as a piece of spaghetti and weighs as little as a straight pin. Yet when expanded, it possesses the capacity to stretch to the vessels largest diameter. As the obstructing cholesterol deposit (plaque) is compressed along the sides of the vessel during an angioplasty, a stent is placed to prevent recoil of the plaque. The stent remains snugly nestled in place against the wall of the vessel acting as scaffolding that supports the artery’s walls. All stents are made of metal.
How is a Stent Implanted?
The stent is usually mounted on a balloon catheter that is passed over a guide wire to the site of narrowing in the artery. Once the catheter is in place, the balloon is inflated expanding the stent and pressing it against the wall of the artery. This catheter is then deflated and removed leaving the stent securely snuggled against the wall of the artery. Another balloon may be used to fully expand the stent once it is in place. One or more stents may be needed to span the length of the narrowing. These stents remain in the artery permanently. Within a few weeks a thin layer of tissue will begin to grow over the stent covering it completely making it a permanent part of the wall of the artery.
Can the Artery Narrow Again?
There are two main causes for restenosis within a stent: blood clot formation and regrowth of tissue. During the first few weeks or months after a stent is implanted, blood clots may form and stick to the surface of the stent. If this happens there will be limited flow in the area of the stent causing you to have symptoms like before the stent was implanted. To help prevent blood clots from forming on the stent, you will go home on antiplatelet therapy (blood thinners).
Over time, narrowing within the stent can occur due to tissue regrowth. This is known as in-stent restenosis. This restenosis develops when excess tissue (scar tissue) forms during the healing process. This excess tissue then acts as a new blockage and symptoms will return same as before the stent was placed. The drug eluting stents help reduce the rate of in-stent restenosis by slowly releasing the drug which reduces the growth of tissue around and within the stent as healing occurs. Your physician will determine which type of stent is best suited for your blockage.
Should restenosis occur, whether it is due to clot formation or tissue regrowth, the treatment is the same. The patient is taken back to the cath lab to determine the cause. Often ballooning within the stent is all that is needed to open the vessel. Other times cutting balloons or other atherectomy catheters are used to clear the area within the stent then ballooning and/or restenting can be done. For many patients this second intervention within the stent seems to remain open without reoccurring restenosis.
Antiplatelet Therapy (Blood Thinners)
Platelets are tiny blood cells that aid in blood clotting. These cells are sticky and when clumped together form blood clots. Antiplatelet drugs work by inhibiting platelet function thus making these cells less sticky. Studies have shown that when people with known atherosclerotic disease (hardening of the arteries or cholesterol blockage) have been placed on antiplatelet drugs there is a significant reduction of strokes, heart attacks, and unstable angina.
During the first 24 hours of stent implantation the patient may receive IV antiplatelet therapy along with oral antiplatelet therapy. You should expect to go home on oral antiplatelet therapy following stent implantation. The most common of these drugs are Aspirin, Plavix, and Ticlid. Aspirin and Plavix are the most commonly used antiplatelet drugs (bloodthinners) following coronary intervention.
You will be on aspirin and Plavix (clopidogrel) for at least 1-3 months following stent implantation and in most cases from 6-12 months. Your physician will determine the length of your antiplatelet therapy depending on the type and number of stents implanted. You will most likely be asked to continue taking a small dose of aspirin the rest of your life unless there are known contraindications to its use. Never stop taking your Plavix and/or aspirin without discussing it with the members of your health team. If you are concerned about the cost of taking Plavix, please let the health care team know immediately. Always remember to tell your physician that you are taking Plavix. If you are in need of elective surgery (this includes oral surgery and eye surgery) you will need to be off Plavix at least 5 days prior to the surgery. Check with your surgeon to see how long before surgery he wants you off the Plavix and how long after surgery before you can restart it. Then always check withyour cardiologist to make sure it is safe to be off Plavix that long or should other arrangements be made. Never assume it will be OK to stop the Plavix just because another physician has requested you to do so without fully understanding the risks of complications that can occur while being off Plavix.
Even though you are walking around with a foreign object inside your body, the body rarely rejects it. You won’t set off alarms at the airport or be launched skyward if you’re caught in an electromagnetic field. In fact most magnets will not dislodge a stent because they are so tiny. But you will be advised not to undergo any MRI or MRA testing within the first 3 months of stent implantation without first checking with your cardiologist.