DEAR DOCTOR K: I recently had an angiogram, and during the procedure the doctor found a blockage. He performed an angioplasty and placed a stent. He said my angina should go away, and it has, but I really don't understand what he did. Can you explain it?

DEAR READER: In a previous column I discussed coronary angiography. That diagnostic test allows doctors to detect blockages from plaques of atherosclerosis in arteries that supply blood to your heart. As in your case, if a doctor finds a blockage during an angiography, he or she may perform an angioplasty and place a stent to open up the blockage. (These procedures are often performed immediately after a heart attack.)

As we described yesterday, to do the angiogram your doctor pushed a soft tube (a catheter) from an artery in your leg or arm up to your heart. Squirting dye through the catheter into the arteries of the heart revealed at least one blockage. Your doctor decided there was a good chance the blockage could be opened by an angioplasty, using the catheter. (Not all blockages can be reached or safely opened by a catheter.)

Here's how an angioplasty works: Inside the catheter used to perform the angiogram is a thinner catheter that has an inflatable balloon near its tip. And inside that catheter is an even thinner wire with a soft tip.

The doctor watches an X-ray machine that shows where the tip of the wire is.


Once the catheter reaches the heart, the doctor guides the wire down the artery until the wire tip is beyond the blockage.

Once the wire has crossed the blockage, the doctor slides the catheter with the little uninflated balloon at its tip down the wire until the balloon is right where the blockage is. Then the physician inflates the balloon. This cracks and compresses the plaque, squashing it against the wall of the artery and making the inside of the artery wider. As a result, blood flows through the area more easily. (I've put a video with an animation describing angioplasty on my website,

Doctors' early experience with angioplasty found that the widening of an artery was often temporary. A few months later, the artery was blocked again. That led to the development of stents.

Stents are amazing little devices. The tubes start with a very narrow center that just fits over the uninflated balloon. When the balloon is inflated at the blockage, the stent also expands. It stays expanded, keeping the plaque squashed against the wall of the artery, allowing good blood flow through the artery. The doctor withdraws the catheter and the deflated balloon, but leaves the expanded stent in place. Most stents are coated with a drug that helps to prevent renarrowing of the artery.

You say you're feeling better. But don't get complacent. Make sure to eat healthfully, exercise regularly and take medications as prescribed.

