Catheter Based Treatment for Coronary Artery Disease
Dateline: 10/19/97
It is the era of miniaturization ... and medicine too follows the times. Minimal invasiveness is the watch-word. The rapidity of developments in catheter delivered treatment methods for coronary artery disease is truly mind-boggling. Why don't you judge for yourself ?
What is an Angioplasty ?
Literally, angioplasty means "fixing" an artery. In heart disease, it is used to describe a method to repair, or dilate, narrowed coronary arteries in a non-surgical, minimally invasive manner. The procedure - called PTCA for Percutaneous Transluminal Coronary Angioplasty - was introduced in the 1980s by Dr.Andreas Gruentzig. It has rapidly evolved, until today, multiple modifications allow usage of PTCA for almost all coronary artery narrowings.
Balloon Angioplasty
In this technique, through a simple needle stick, a tube called a catheter is passed into a groin artery and guided to the heart. A small balloon is threaded over this catheter into the narrowed coronary artery and the balloon is inflated. The area of narrowing is dilated, thus restoring normal blood flow through it. Sounds simple, isn't it ? In fact, as the procedure is performed under local anesthesia, the patient can actually observe the entire process on the video monitor....if indeed he or she is so inclined !
What next...?
Certain conditions prevented simple balloon dilation. For instance, some arteries were so narrow that the balloon could not be passed across it. Guess what the "tube-pushers" did next....Give up ? No way...They decided to cut or grind their way through !
Tunnelling through....Atherectomy
Tiny metal drills were fitted onto the tip of catheters. When they reach the area of severe narrowing, these drills rotate at extremely high speeds. They abrade the plaque, and create a channel through which a balloon can then be passed.
Or blazing a trail...Lasers
Alternatively, using laser energy transmitted to the tip of a catheter, a trail can be cut through the toughest plaque. A balloon can then pass easily. Of course, there is the risk of cutting right through the artery wall, and that could be catastrophic. "Smart" lasers have been invented, which measure the depth of the artery wall, and stop before they puncture the wall.
New techniques....New problems
Anything achieved is necessarily at a price. Since severely blocked arteries were now being opened up using drills and lasers, new difficulties arose. The artery which was drilled through had a tendency to suddenly collapse and get totally occluded as soon as the balloon was removed. And such a situation is obviously dangerous, as blood supply to the heart is suddenly cut-off, resulting in a heart attack. To avoid this situation, cardiologists came up with the idea of using "stents" to keep angioplastied arteries open. I'll write more about stents in another article.
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