Shortcomings of Balloon Angioplasty: Firstly, the opening created by the procedure is not very smooth since the balloon does not evenly expand all areas with different degrees of hardness (atheroma (fatty collection) is soft, plaques are hard and a mixture of the two have a medium and uneven degree of hardness). This produces a channel with an irregular shape and a rough surface that is covered with superficial or deep cracks. The irregular surface and the cracks on the inner surface of the artery blockage increases the risk of total arterial blockage in some patients. The picture on the left (below) shows a blockage prior to angioplasty, while the picture in the middle demonstrates the artists rendition of the angioplasty results.
     
Secondly, some of the compressed material tends to "spring back" to some degree. This is known as "recoil." Recoil causes the channel to become smaller shortly after being enlarged by balloon expansion. Moreover, within days, the material in the expanded channel starts to multiply. This build-up narrows the previously opened channel. In 30-60% of cases, the build-up of material can be large enough to cause the severity of the blockage to return to its original or even worse state. This occurs over a 6 week to 6 month duration of time and is known as restenosis.
The picture on the left (below) shows a cross-section of a coronary artery at the level of a blockage or stenosis. The diagram on the extreme right shows an increased opening after the blockage was treated with a coronary stent.
   A stent is a metal "mesh" that is mounted on an angioplasty balloon. When the balloon is inflated, it expands the stent and opens up the diseased segment into a rounder, bigger and smoother opening (compared to angioplasty, which is shown in the middle picture as having a more "frayed" appearance). Stents induce a more predictable and satisfactory result, reduces the risk of the artery abruptly closing off during the procedure and also decreases the chance of restenosis (recurrence of the blockage) by nearly 50%.
     
  Like angioplasty, coronary stents physically opens the channel of diseased arterial segments, relieves the recurrence of chest pain, increases the quality of life and reduces other complications of the disease. Since it is performed through a little needle hole in the groin (or sometimes the arm) it is much less invasive than surgery and can be treated with another needle or percutaneous procedure should the patient develop disease in the same, or another, artery in the future.

How is coronary artery stenting performed

How is Coronary Artery Stenting performed? Prior to performing stenting, the location and type of blockage plus the shape and size the coronary arteries have to be defined. This helps the cardiologist decide whether it is appropriate to proceed with angioplasty or to consider other treatment options such angioplasty, atherectomy, medications or surgery. Cardiac catheterization (cath) is a specialized study of the heart during which a catheter or thin hollow flexible tube is inserted into the artery of the groin or arm. Under x-ray visualization, the tip of the catheter is guided to the heart. Pressures are measured and an x-ray angiogram (angio) or movie of the heart and blood vessels is obtained while an iodine-containing colorless "dye" or contrast material is injected into the artery through a catheter. The iodinated solution blocks the passage of x-rays and causes the coronary arteries to be visualized in the angios. In other words, coronary arteries are not ordinarily visible on x-ray film. However, they can be made temporarily visualized by filling them with an iodine containing contrast solution that blocks x-ray. This is similar to creating a shadow of an object on a screen by using it to block the light. 

Tip of catheter being inserted into the opening of a coronary artery   As discussed in the cardiac cath section, a sheath is introduced in the groin (or occasionally in the arm). Through this sheath, a long, flexible, soft plastic tube or guiding catheter is advanced and the tip positioned into the opening or mouth of the coronary artery. In the picture below, the catheter tip is positioned in the mouth of the left main coronary artery.
The tube measures 2 to 3 mm in diameter. The tip of the catheter is directed or controlled when the cardiologist gently advances and rotates the end of the catheter that sits outside the patient.
Once the catheter tip is seated within the opening of the coronary artery, x-ray movie pictures are recorded during the injection of contrast material or "dye."

This page was reviewed and updated on August 28, 2011

After evaluating the x-ray movie pictures, the cardiologist estimates the size of the coronary artery and selects the type of balloon catheter and guide wire that will be used during the case. Heparin (a "blood thinner" or medicine used to prevent the formation of clots is given. In most cases, coronary stenting is preceded by angioplasty. This is known as "pre-dilation." It helps open up the blockage area, and makes it easier to deliver the stent. If pre-dilation is not used, the procedure is called "primary stenting".
  The guide wire which is an extremely thin wire with a flexible tip is inserted into the catheter. The tip of the wire is then guided across the blockage and advanced beyond it. This wire now serves as a "guide" or rail over which the balloon catheter is passed. The tip of the stent balloon catheter is then positioned across the lesion. The balloon is situated on the tip of the catheter shaft and is inflated by connecting it to a special hand-held syringe pump. A mixture of saline and contrast material is used to inflate the balloon. The balloon catheter has metallic markers (at either side of the balloon). The unexpanded stent is mounted just inside these visible metallic markers that helps the cardiologist know the location of the otherwise poorly visible stent.
 Inflation is initially carried out at a pressure of 1 - 2 times that of the atmosphere and then increased to 8 - 12 and sometimes as high as 20 atmospheres, depending upon the type of stent that is used. The handheld inflation syringe has markers that are used to determine the pressure. The balloon is kept inflated for 30 to 60 seconds and then deflated. The expanded stent is embedded into the wall of the diseased artery, holding it open. If not satisfied by the results, the cardiologist will further expand the stent using another balloon (frequently it is the same balloon catheter that was used for "pre-dilation.".
 
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