In 1977 in Zurich, Switzerland, a young German physician named Andreas Gruentzig inserted a catheter into a patient's coronary artery and inflated a tiny balloon, opening a blockage and restoring blood flow to a human heart. Today more than 1 million coronary angioplasties are performed each year worldwide, making it the most common medical intervention in the world.

First introduced by Dr. Charles T. Dotter in 1964, transluminal angioplasty is a mechanical solution to a biological problem. Plaque build-up in the coronary arteries reduces blood flow to the heart. If untreated, such blockages can cause symptoms ranging from mild chest pain to a heart attack. Angioplasty removes or compresses plaque nonsurgically. Dotter, a vascular radiologist at the University of Oregon in Portland, used multiple catheters of increasing diameter to open blocked arteries and improve blood flow in patients with arteriosclerosis in peripheral (leg) arteries.

In balloon angioplasty, a physician threads a catheter -- a long, flexible, hollow tube -- through an entry site in the groin, arm or wrist into an artery. The catheter is pushed up to the left or right coronary artery. Special dyes and X-rays allow the physician to see the blockage and watch the procedure as it happens. Through this hollow catheter, the physician inserts a tiny balloon until it reaches the blockage site. Once there, the balloon is inflated, usually several times, to compress the plaque against the artery wall, much like footsteps in snow.

Although this procedure was first envisioned as simply an alternative to open heart bypass surgery in only a handful of patients, today angioplasty accounts for more than half of the treatments for coronary artery disease. Biomedical engineering and advances in technology have not only optimized basic balloon angioplasty, but also added the use of stents, lasers and other interventional devices that restore normal blood flow while minimizing damage to the heart muscle.

Stents are now used in more than half of angioplasty interventions. These are tiny metal structures, which, like the balloons, come in a variety of sizes and designs. The stent is mounted on an angioplasty balloon and delivered to the diseased area. When the balloon inflates, the stent opens along with it. When the balloon is deflated and withdrawn, the stent remains in place, serving as a permanent scaffolding for the newly widened artery. Within a few weeks, the endothelium, the artery's natural lining, grows over the stent, anchoring it in place.

Stents have virtually eliminated many of the complications of regular balloon angioplasty, such as abrupt and unpredictable closure of the vessel, which requires emergency bypass surgery.

An additional development in the last several years has introduced lasers to the procedure. Some catheters have been fitted with special lasers that can photo-dissolve the tissue obstructing the arteries. Another companion device now available is the rotational atherectomy catheter, an olive-shaped diamond burr that rotates at extremely high speed. If the plaque is too hard or calcified to be pushed by the balloon, a cardiologist can use the device like a sander to pulverize the obstruction into harmless microscopic particles that are washed away by the blood.

Biomedical engineering research continues to improve angioplasty and address ongoing problems associated with the procedure. One problem occurring about one-third of the time is restenosis, in which the body's immune system responds to the angioplasty as if it were an injury, resulting in scare tissue buildup and further blockage. The use of stents has lowered the rate of restenosis, and new types of devices that release clot-deterring medicine or even certain forms of radiation are being developed to reduce this problem even further. One solution is to combine a stent with gene therapy. Several investigations are in progress to determine the effective dose levels and optimum delivery systems of gamma or beta radiation, which have been shown to suppress restenosis.

With the invention and refinement of intravascular coronary ultrasound (IVUS), it is now possible to thread a tiny ultrasound camera into the coronary arteries to give a valuable cross-sectional view from the inside out, showing the physician where the normal artery wall ends and the plaque begins. Research conducted using IVUS has also shown that one of the causes of restenosis may be inadequate dilation.

A recounting of the first angioplasty procedure in 1977 (about 2.5 min.).