Interventional cardiology is a specialty area within the larger field of cardiology. Interventional cardiologists are specialists in cardiovascular disease who have had one to two years of education and training specifically in the use of catheters – thin, flexible tubes – to perform cardiovascular procedures. These procedures, such as angioplasty and stenting, are performed by guiding tools through the body’s arteries. For many patients, these minimally invasive interventional procedures are an appropriate alternative to open surgery.
See below for a list of tools and devices commonly used for interventional procedures. If you are a patient considering an interventional procedure, learning about the tools and devices that may be used can be part of your personal toolbox for understanding your procedure.
A catheter is a slender, plastic tube that can be placed at the beginning of a blood vessel to deliver treatments inside that blood vessel. During a diagnostic angiogram, x-ray dye flows through the catheter into the arteries so that your cardiologist can view images of any blockages in the artery. During angioplasty, a balloon or another device is mounted on the catheter’s tip and guided to the narrowed section of the artery over a guide wire. The device on the catheter is then used to reopen the artery for blood flow.
A guide wire is a long and flexible fine metal wire used to place balloons or stents. The guide wire is threaded through a blood vessel to the site where treatment will be delivered. A balloon or stent is then fed over the guide wire until it is in the desired position. A guide wire does just as it name implies: it helps your interventional cardiologist guide other devices into place.
Angioplasty balloons are inflatable portions of catheters. An interventional cardiologist threads a balloon catheter over a guide wire to the site of a blockage in a blood vessel. The balloon portion is then inflated and deflated several times to push the blockage (formed of a fatty substance called plaque) aside and restore blood flow in the artery.
A cutting balloon is a catheter device with a special balloon tip containing small blades that are activated when the balloon is inflated. Used to treat plaque that is resistant to a traditional balloon, the small blades score the plaque, and then the balloon compresses the fatty matter into the wall of the artery.
A stent is a small, metal mesh tube that is placed by a catheter and permanently embedded within the artery. A stent acts as a tiny scaffold to prop an artery open and prevent it from collapsing. Your doctor may choose from two types of stents: bare metal and drug-eluting, depending on the size of the artery and the location of the blockage and other factors specific to your condition.
Vascular closure devices
After an interventional procedure, your doctor will close the puncture site in your skin where catheters were inserted into your artery. Common examples of closure devices for artery access through the groin include a collagen plug or a stitch. If the interventional procedure is performed through an access point in the wrist, the closure device generally consists of bands that go around the wrist, with either air (for compressive purposes) or compounds that stop bleeding in the band.
Sometimes the fatty substance called plaque that builds up in arteries - eventually restricting blood flow - is hardened through the presence of calcium in the blockage. If a plaque is severely calcified, a standard angioplasty balloon may not be able to cross the blockage and push it to the sides of the artery upon inflation. Rotational atherectomy is a procedure that can be performed to drill through tough blockages, using a tiny rotating cutting device to open a narrowed artery and improve blood flow. The pieces of plaque dislodged by the rotational atherectomy device are small enough to be absorbed by the blood stream.
Intravascular ultrasound (IVUS)
Intravascular ultrasound (IVUS), like any form of ultrasound, uses sound waves to create images of a part of the body. IVUS is used to gather images of the inside of arteries to find out if a blockage is present, and if so, to what extent.
During an IVUS test, a catheter with an ultrasound probe at the end is threaded over a guide wire in the artery to the area to be tested. The ultrasound catheter sends out sound waves and receives echoes from the sound waves as they bounce back from the body’s tissues. These echoes are translated by a computer into images of the artery. IVUS is useful in assessing lesions that appear borderline severe on an angiogram test. IVUS can measure the amount of plaque inside vessels as well as how much cross-sectional area is left in the blood vessel for blood to flow through. IVUS also helps to optimize angioplasty and stent procedures in complex blockages and is widely available.
Fractional flow reserve (FFR)
Fractional flow reserve (FFR) is a procedure for measuring how much blood flow is restricted by a blockage in an artery. A special, pressure-sensing guide wire is fed through a catheter to the site of a stenosis, or blockage, in an artery.
The wire, when placed across the blockage, measures the flow and pressure of blood before and after the blockage. If the blood pressure in the artery on the side of the artery beyond the blockage is found to be significantly reduced, that blockage may be a good candidate for angioplasty and stenting to clear the blockage and prop the artery open.
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Dr. Morton J. Kern, University of California, Irvine, describes tools and techniques physicians use to make certain a procedure is necessary.
Optical coherence tomography (OCT) imaging
Optical coherence tomography (OCT) is an imaging method for taking high-resolution pictures of blood vessel walls. OCT, which was recently approved for cardiac use in the United States provides interventional cardiologists with detailed images of plaques, build-up of cholesterol and other materials in blood vessel walls that can rupture, causing a blood clot to form at the site and block off critical blood flow. Like IVUS, this detailed information about plaque build-up in arteries can help interventional cardiologists determine where best to place stents and to optimize angioplasty and stent procedures. It is now increasingly available in the United States.