Interventional Cardiology

This is a procedure to examine blood flow to the heart and test how well the heart is pumping.A doctor inserts a thin plastic tube (catheter) (KATH’eh-ter) into an artery or vein in the arm or leg. From there it can be advanced into the chambers of the heart or into the coronary arteries.

This test can measure blood pressure within the heart and how much oxygen is in the blood. It’s also used to get information about the pumping ability of the heart muscle. Catheters are also used to inject dye into the coronary arteries. This is called coronary angiography (an”je-OG’rah-fe) or coronary arteriography (ar-te”re-OG’rah-fe). Catheters with a balloon on the tip are used in the procedure called coronary angioplasty (commonly referred to as percutaneous coronary intervention[PCI]). Catheterization of the heart may also be done on infants and children to examine for congenital (kon-JEN’ih-tal) heart defects.

Angioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel; typically as a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size using water pressures some 75 to 500 times normal blood pressure (6 to 20 atmospheres). The balloon crushes the fatty deposits, so opening up the blood vessel to improved flow, and the balloon is then collapsed and withdrawn.

A stent is a wire metal mesh tube used to prop open an artery during angioplasty. The stent is collapsed to a small diameter and put over a balloon catheter. It’s then moved into the area of the blockage. When the balloon is inflated, the stent expands, locks in place and forms a scaffold. This holds the artery open. The stent stays in the artery permanently, holds it open, improves blood flow to the heart muscle and relieves symptoms (usually chest pain). Within a few weeks of the time the stent was placed, the inside lining of the artery (the endothelium) grows over the metal surface of the stent.

When are stents used?
Stents are used depending on certain features of the artery blockage. This includes the size of the artery and where the blockage is.Stenting is a fairly common procedure; in fact,over 70 percent of coronary angioplasty procedures also include stenting.

What are the advantages of using a stent?
In certain patients, stents reduce the re-narrowing that occurs after balloon angioplasty or other procedures that use catheters. Stents also help restore normal blood flow and keep an artery open if it’s been torn or injured by the balloon catheter.

Can stented arteries reclose?
Yes. Reclosure (restenosis) is also a problem with the stent procedure. In recent years doctors have used new types of stents called drug-eluting stents. These are coated with drugs that are slowly released and help keep the blood vessel from reclosing. Stents that are not coated with drugs are called bare metal stents. As detailed below, it is very important that patients with either type of stent take their anti-clotting medicines as directed.

What precautions should be taken after a stent procedure?
Patients who’ve had a stent procedure must take one or more blood-thinning agents. Examples are aspirin and clopidogrel. These medications help reduce the risk of a blood clot developing in the stent and blocking the artery. Some recent studies have suggested that blood clots may develop later on (more than a year after stent placement) in the drug-eluting stents. Therefore it is really important to stay on your medications as long as your cardiologist recommends. Aspirin is usually recommended for life, and clopidogrel is generally used for one to 12 months (depending on the type of stent) after the procedure. Clopidogrel can cause side effects, so blood tests will be done periodically. If you are taking this medication, it is important that you don’t stop taking it for any reason without consulting your cardiologist who has been treating your coronary artery disease..

For the next four weeks a magnetic resonance imaging (MRI) scan should not be done without a cardiologist’s approval. Metal detectors don’t affect the stent.

Atherectomy (ath”er-EK’to-me) is a procedure to remove plaque from arteries. Plaque is the buildup of fat, cholesterol and other substances in an artery’s inner lining.

Coronary atherectomy removes plaque from the arteries supplying blood to the heart muscle. It uses a laser catheter, or a rotating shaver (“burr” device on the end of a catheter). The catheter is inserted into the body and advanced through an artery to the area of narrowing. Other devices are dissectional catheterectomy, catheters that shave off the plaque, or laser catheters that vaporize the plaque. Balloon angioplasty or stenting may be used after an atherectomy.

Persons with plaque buildups in the carotid (kah-ROT’id) arteries or major arteries of the neck are at higher risk for stroke. Carotid endarterectomy (end”ar-ter-EK’to-me) is an effective surgical procedure that can help them. It removes the plaque to reduce the risk of stroke.

The decision to use these procedures must be made by a physician.

Cardioversion refers to the process of restoring the heart’s normal rhythm by applying a controlled electric shock to the exterior of the chest. Abnormal heart rhythms are called arrhythmias or dysrhythmias. When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin its normal rhythm and pump more efficiently.

Cardioversion is used to treat many types of fast and/or irregular heart rhythms. Most often, cardioversion is used to treat atrial fibrillation or atrial flutter. Life-saving cardioversion can be used to treat ventricular tachycardia and ventricular fibrillation.

Abnormal heart rhythms are slightly more common in men than in women and the prevalence of abnormal heart rhythms, especially atrial fibrillation, increases with age. Atrial fibrillation is relatively uncommon in people under age 20.

Elective cardioversion is usually scheduled ahead of time. After arriving at the hospital, an intravenous (IV) catheter will be placed in the arm to deliver medications and fluids. Oxygen may be given through a face mask. In some people, a test called a transesophageal echocardiogram (TEE) may need to be performed before the cardioversion to make sure there are no blood clots in the heart.

A short-acting general anesthetic will be given through the IV to put the patient to sleep. During the 5 or 10 minutes of anesthesia, an electric shock is delivered through paddles or patches placed on the exterior of the chest and sometimes on the back. It may be necessary for the doctor to administer the shock two or three times to stop the abnormal heartbeat and allow the heart to resume a normal rhythm. During the procedure, the patient’s breathing, blood pressure, and heart rhythm are continuously monitored.

Pacemakers and Implantable Cardioverter Defibrillators (ICDs) are used to treat arrhythmias— a condition of heart rhythm problems that occurs when the electrical impulses that coordinate your heartbeats don’t function properly, causing your heart to beat too fast, too slow or irregularly. The Left Ventricular Assist Device (LVAD) helps maintain the pumping ability of your heart.