Cardiac catheterization refers to a variety of invasive procedures used for the diagnosis of heart disease, including coronary artery disease.
Coronary intervention (angioplasty) refers to a variety procedures used for the treatment of coronary artery disease. For many patients these treatments may provide an alternative to medical or surgical therapy.
The heart consists of four muscular chambers that act in concert to pump blood throughout the body. The blood is pumped through a system of blood vessels called arteries and veins. The heart muscle itself is supplied with blood through some of these vessels which are called coronary arteries.
Coronary artery disease is a condition that occurs when the coronary arteries become narrowed and obstructed due to growth of atherosclerotic plaque within the vessel. This plaque is most typically composed of a combination of scar tissue, fat deposits, calcium and sometimes thrombus (blood clot). Obstructing plaque decreases the amount of blood that can be delivered to the heart muscle. Such a decrease in blood flow may be the cause of chest discomfort (angina pectoris), shortness of breath (congestive heart failure, dyspnea) or even permanent damage to part of the heart muscle (heart attack, myocardial infarction).
Cardiac catheterization and coronary intervention is performed in the cardiac cath lab with the use of catheters. Catheters are long thin flexible tubes that are inserted into the heart and allow for the injection of contrast dye and the creation of xray images of the coronary arteries. They can also be used to measure pressure in the heart and lungs, sample blood oxygen levels and deliver stents and other treatment devices. The catheters are inserted into a blood vessel through very small (1/10 of an inch) incisions in either the groin or wrist. Once the catheters are inserted into the vessel they are advanced to the heart and the procedure is performed with x-ray guidance. The procedures usually last from 30 to 90 minutes depending on the particular situation. They are performed with the use of local anesthesia and intravenous sedation so that there is minimal or no discomfort.
Both routine and very advanced techniques to diagnose and treat coronary artery disease are employed on a regular basis at the Hartford Cardiac Lab.
Coronary angiography. The most common technique for diagnosing blocked coronary arteries is called coronary angiography. During this procedure contrast dye is injected through a catheter into a coronary artery and an x-ray image of the artery is created. This image can reveal the presence or absence of atherosclerotic blockages in the coronary arteries. If blockage(s) are present, these images will help determine what the most appropriate treatment should be.
Intravascular ultrasound. Intravascular ultrasound is a more advanced technique for imaging the arteries. It allows for a more precise image of the inside of the artery that cannot be obtained with routine coronary angiography. It can also give information on the composition of the obstructing plaque and the severity of the narrowing, information that is often useful for guiding therapy.
Pressure Wire Assessment. Another advanced technique is the use of a pressure wire. This device is used to measure the pressure on both sides of a vessel blockage thereby allowing for a more precise calculation of how severely narrowed the vessel is. This information often helps to guide further therapy.
Balloon angioplasty. Balloon angioplasty was the original coronary intervention technique, developed in 1977, and provided a therapeutic alternative to the medical and surgical treatments of coronary artery disease. The balloon catheter consists of a catheter with a tubular balloon situated on one end. The balloon typically ranges in size from 15-20mms (0.5-1.0 inches) in length and 2-4mms in width. During angioplasty the balloon is situated at the site of blockage and inflated, stretching the artery open. The balloon is then removed leaving a widened, unobstructed vessel behind. This technique is now most often used in conjunction with the placement of a coronary stent (see below).
Coronary stenting. The most common technique for the treatment of blocked coronary arteries is the placement of a coronary stent. A stent is a small, metal, tubular mesh that commonly measures 2-4 mms in diameter and 10-20 mms in length. It is wrapped around the balloon of a balloon catheter and is delivered to the blocked segment of the artery. The balloon is inflated thereby deploying the stent. The balloon catheter is then removed leaving the stent behind. The stent acts as a scaffolding to keep the artery open.
Coronary thombectomy. Some coronary blockages may have blood clot (thrombus) associated with them. Blood clot increases the risk of an angioplasty procedure and decreases the likelihood of obtaining a good result. To treat this, specially designed thrombectomy catheters that employ a suction mechanism can be used to remove the clot prior to balloon angioplasty and stenting.
Coronary atherectomy. Some coronary blockages are stiff and calcified thus preventing the full expansion of balloons and stents. To treat this, drill-like devices are used that can remove the hard dense plaque thus allowing full deployment of stents. One such device is the rotational atherectomy catheter. This catheter employs a diamond-tipped brass burr that can drill though dense, calcified, rocklike plaque. This not only widens the artery but allows easier placement of a stent.
A newer and more advanced atherectomy device, the Diamondback catheter, is being used at Hartford hospital. This device employs an innovative jump-rope like action of a diamond dust-embedded brass burr to open up blocked arteries. This new device has the potential to greatly simplify the atherectomy procedure.
Cutting balloon. Another device for the treatment of very stiff coronary blockages is the cutting balloon. This device employs very thin razor blades that are attached to the balloon surface. When the balloon is inflated in a coronary lesion, the razors split the plaque thus allowing both easier stretching of the narrowed artery and easier placement of a stent.
Acute Myocardial Infarction Angioplasty. Acute myocardial infarction (heart attack) occurs due to the sudden closure of a coronary artery, usually precipitated by the formation of a blood clot. Such a situation constitutes a medical emergency as it is important to transfer the patient to a cath lab as quickly as possible to reopen the blocked artery. This requires a complex coordinated team effort consisting of both emergency room and cath lab personnel. Hartford Hospital has a vast experience in this field and has been a regional leader in the treatment of emergency acute myocardial infarction angioplasty for over two decades.
Chronic Total Occlusions Angioplasty. Chronic total occlusions are arteries that have been completely blocked for very long periods of time. These arteries have historically been very difficult to treat and until recently surgery was the only reasonable option.
Over the past several years, complex cath lab techniques have been developed by which these arteries can now be opened with the use of balloons and stents thereby avoiding the need for surgery.
Hartford Hospital has been a regional leader and referral center for the treatment of chronic total occlusions.