NEW CARDIAC CT SCANS

Heart disease remains the leading cause of death in the United States, claiming over one million lives each year. Atherosclerosis is the progressive narrowing of arteries by fatty plaque. In the heart, this involves the coronary arteries. Progressive narrowing of the coronary arteries leads to severe chest pains (angina pectoris), heart attack (myocardial infarction), and/or death. Fortunately, with a combination of lifestyle changes, medications, angioplasty, stents, and coronary bypass, the disease can be treated with excellent long-term results. Unfortunately, waiting for symptoms to occur before administering any treatment is often too late. In one half of all coronary patients the first symptom is either a myocardial infarction or sudden death. Identifying patients with an earlier stage of the disease leads to a dramatic improvement in quality of life and survival.

Until now, the most accurate procedure in measuring the degree of coronary plaque was the coronary angiogram (heart catheterization). This involves threading a tube from the groin or arm into the openings of the coronary arteries and injecting the arteries with a contrast agent to visualize the inside of the vessels. This procedure, in general, is quite safe. However, the potential complications of having a catheter in the heart, the discomfort, the 6-8 hour hospital stay, and the cost (at least $7000-$8000), makes it a less useful screening tool for the general population or patients with mild disease. To find disease in these patients, other less invasive but less successful tools have been used for imaging the coronary arteries. These tools have not been fast or accurate enough to photo or image coronary arteries or the constantly beating heart.

Computed Tomography (CT) scans are a specialized form of an X-ray exam. In the past few years, newer generation CT scans have been able to image the heart to a better degree and measure calcium in the walls of coronary arteries. It is thought the presence of calcium in the wall may be an early sign of atherosclerosis. Unfortunately, these CT scans don't measure the degree of obstruction present within the vessel. High amounts of calcium do not always mean severe coronary blockage and vice versa. These machines were still unable to accurately visualize the coronary arteries and plaques themselves.

The latest advance in CT scanning has been the addition of "multi-detector rows." First dual and now 4-slice multidetector scanners are being used. The larger the number of slices, the more of the heart can be imaged in a given time span, making it easier to capture a true picture of a moving target. The newest generation, 8-slice CT scans are now fast enough to accurately look at a large portion of the coronary arteries themselves, using CT angiography.

Unlike standard coronary angiography, CT coronary angiography can be performed more quickly, comfortably and affordably. The scan can be done at an outpatient facility. It only requires the starting of an I.V. and less than 15 minutes in the scanner and the patient will then be able to immediately depart. Not only will the patient have a coronary calcium score but also a complete 3-D reconstruction of the coronary vessels. No longer will angiograms have to be done in the hospital. In addition to angiography, the faster scanner will allow better visualization of the cardiac structures, helping to treat complex congenital heart and other cardiac diseases.

The 8-slice CT scan is a revolutionary tool in the evaluation and treatment of cardiac patients. This will be an incredible aid in diagnosing the presence of coronary atherosclerosis and also in monitoring the patient as therapy is initiated and modified. Following coronary bypass procedures or intracoronary stents, the 8-slice scan will become the procedure of choice in following the grafts and stents through time for renarrowing. And with the 8-slice scanner, any other artery or vein in the body can be visualized as safely and quickly.

This scanner will also be able to visualize other organs with improved sensitivity. Recent data suggest lung screening for cancer may be most accurate with the 8-slice machine. Brain images may be as good as an MRI without worrying about pacemakers, artificial hips or other metallic implants. Virtual colonoscopy may be close to actual colonoscopy in detecting cancer.

In October 2001, the first of the newest 8-slice multidetector CT scans in the world will be coming to our city. Sacramento Heart has been selected as the first of five test sites in the country, working with General Electric in evaluating and advancing the capabilities of this machine. We feel privileged to have been selected and to be able to offer this leading edge technology to our patients. For further information call the Sacramento Heart Center at 830-2080.

Dr. Philip M. Bach, MD, FACC is affiliated with the Sacramento Heart Center. For more information about the Sacramento Heart Center, visit their web site at www.sacheart.com or call (916) 830-2080 and request information be mailed to you. Please address your cardiology-related questions to "Ask the Cardiologist", 500 University Avenue, Sacramento, CA 95825. Selected questions will be answered in future articles.