What are angioplasty and stent placement?
The heart is a muscle that is always beating, necessitating a constant supply of blood and oxygen and nutrition. It gets this blood supply from three major arteries and their branches, called the coronary arteries. It is these same arteries that can become clogged over time with cholesterol-laden deposits, called atherosclerotic plaques. If these plaques grow over time to cause a severe narrowing of the coronary artery, then the blood supply to one or more of the walls of the heart can become compromised. Usually this is manifested as a stable condition called angina that occurs if the demand for blood is greater than the narrowed artery can supply; angina is typically experienced as chest discomfort that occurs with exertion; however, variants of this "typical" chest discomfort can occur, especially in women, in which symptoms can include shortness of breath, abdominal pain, palpitations, and sweats. If these symptoms occur, a cardiologist can perform a number of different kinds of stress tests, designed to bring out these symptoms of angina under very controlled and safe circumstances.
The doctor can then evaluate, usually with the aid of an imaging modality such as nuclear imaging or echocardiography (ultrasound of the heart), just how much of the heart lacks an adequate blood flow at the peak of stress, and just how severe that lack of blood flow is. In certain people with angina who have a mildly abnormal test, medical therapy with pills is likely to be as effective as the more invasive strategies. However, if the imaging reveals a moderate to severe limitation in blood flow at peak stress versus rest, then a procedure to open the blocked artery must be performed.
This procedure, called angioplasty with stent placement has evolved to become an extremely advanced procedure in recent years. First, a thin flexible plastic catheter is advanced through an artery at the top of the leg under x-ray until it gets to the heart. Dye is then injected into each of the coronary arteries and a movie is taken in order to determine exactly where and how severe the blockage or blockages are. If there are one or two tight discrete blockages, then a wire with a tightly wrapped tiny balloon can be advanced across the narrowed segment; the balloon is inflated under very high pressures, thereby crushing the cholesterol plaque up against the wall. The balloon is removed, and a tiny metal scaffold wrapped on a balloon, is then advanced into the area and blown up against the wall under high pressure. The balloon is removed, leaving the stent permanently embedded in the wall. The stent helps keep the artery open significantly better than balloon angioplasty alone.
What is coronary artery bypass graft surgery (CABG)?
In general, if all three of the main coronary arteries have multiple, severe blockages, then angioplasty traditionally was not possible, and only bypass surgery is proven to work. Today, if there are too many diffuse blockages in all three of the main coronary arteries, bypass surgery is still the only viable option. If, however, there are tight, discrete blockages in all three coronary arteries, then studies show that the five-year survival rate with multivessel angioplasty is equivalent to bypass surgery. The caveat is that the multivessel angioplasty patient will likely require several more angioplasty procedures during the next five years, but with much lower early risk. The bypass patient will have a higher early risk, but usually requires significantly fewer repeat procedures over the next five years. Diabetic patients are the exception—they tend to do better with bypass surgery than angioplasty. A recent study, the BARI trial, showed that diabetics tend to do better with bypass than angioplasty. It is hypothesized that diabetic blood vessels are more dysfunctional, and are more likely to block up again after angioplasty (a process called restenosis).
How effective are invasive treatments for heart attacks?
An acute myocardial infarction (MI, or heart attack) is a time-sensitive emergency. One of the coronary arteries has suddenly become blocked, and the part of the heart muscle supplied by that artery will start to die. Therefore, time is of the essence. Traditionally, "clot-busting" medications have been acutely injected immediately upon arrival to the emergency room in order to attempt to open the blood clot that has suddenly blocked up the cholesterol blocked artery. In the 1990s, as angioplasty and stenting technologies have dramatically improved, studies have started to show that immediate angioplasty, as long as it can be performed in a very timely fashion by experienced cardiologists, is superior to the immediate administration of "clot-busting" medications.
What is ultrafast CT?
Ultrafast CT scanning is a novel technology using advances in CT scanning that can non-invasively image the coronary arteries for the presence of calcification. Calcification occurs over the years because of cholesterol blockages. The absolute volume of calcium and how many coronary arteries can be counted. Normal percentile values for males and females of different ages are known; calcium scores above the 75th percentile for age and gender have a higher predictive value of both significant cholesterol blockages and future heart attacks. It is also now known that with aggressive cholesterol lowering medication, calcium scores can decrease from year to year. The test takes about 10 minutes and requires no intravenous medication at all.
Can vitamins or supplements help prevent heart attacks?
Although vitamins and supplements are widely used, the data demonstrating prevention of first heart attacks is limited. In the Nurses Health Study, an observational study of more than 100,000 post-menopausal women with no prior history of coronary artery disease, showed that those who took vitamin E had a lower risk of heart attack. Subsequent studies have raised significant doubt about the utility of vitamin E and other antioxidants in the primary prevention of heart attack. It is clearly known, however, that second heart attacks can definitely be prevented with the use of supplements such as fish oil (omega-3 fatty acids).
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