Kaiser cardiologist Paul C. Ho listened to Bill Duncan's heart during a recent checkup.

Bypass debris trap
cuts cardiac risks

A new protection procedure
reduces heart attacks and deaths

By Helen Altonn

With four bypasses for plugged arteries, interventional cardiologist Paul C. Ho eventually may need a procedure that only he is certified to perform in Honolulu.

Ho, 39, directs Cardiac Catherization and Interventional Cardiology at Kaiser Permanente's Moanalua Medical Center.

He and his lab are the first in Hawaii certified by Medtronic Inc. to use a system it developed to protect coronary vessels from potentially damaging debris during vein graft angioplasty.

Bill Duncan, who will celebrate his 75th birthday Sept. 16, was one of Ho's first patients to benefit from the procedure.

Duncan, who had five coronary bypasses in April 1991, was cutting the grass at his Hawaii Kai home last October when suddenly he began having chest pains.

He stopped and rested a little, then began working again, he said. "It came on and off about three or four times. Stupidly, I didn't do what I was supposed to have done. I didn't take nitroglycerin."

Duncan called Kaiser the next day, went in for tests and on Oct. 17 had angioplasty for one vein graft blockage.

In an extra step to the procedure, Ho used special devices to trap debris knocked loose when the plaque was broken, and suck it out before it went downstream toward the heart vessels.

Bypass grafts using veins from the legs or body can develop repeat blockages in an average of five to 10 years, he said, adding that about 90 percent will close in 10 to 15 years.

"Heart disease knows no age, and as people live longer into the 70s and 80s, grafts are older and need to be looked at as plaque builds up again," said Coraleen T. Grothaus, coronary intervention coordinator, who works with Ho.

Vein graft blockages are removed in the same way blockages are removed from arteries -- with a balloon inflated to crack the blockage and a stent to support the artery or graft when it is opened.

However, vein grafts develop a lot of grungy material or cellular deposits that normally do not occur in arteries, Ho said.

"If you go in with a balloon or stent and knock these deposits loose, they go downstream, like trash in a river, toward the heart."

The debris, called emboli, can shower and plug up the tiny vessels or capillaries and stop blood flow to the artery, he said.

It is worse than a single blockage, Ho pointed out, because the deposits are too embedded in the capillary system to get out and can result in heart attack or death.

"So when we do balloon angioplasty and stenting in the vein graft, there is more risk than when we do it in native arteries," he said.

"The chance of having a heart attack and even death from vein graft intervention is much higher because essentially there are no methods of handling the debris."

But there is higher risk of heart attack and death if blockage in the vein graft is not removed, he said. "So the risk benefit favors the patient."

In the "coronary distal protection system," as it is called, a wire as thin as human hair with a soft balloon is threaded through a plastic tube or catheter from the groin through the aorta beyond the blockage to trap particles from the angioplasty. It is called a GuardWire because it guards the vessels from debris, Ho said.

The wire serves as a guide for the angioplasty balloon and stent, which are threaded over it through the tube to the blockage where the balloon is inflated.

"At the end of the procedure," Ho said, "we go in with an aspirator catheter or suction device, a little tube with a straw, and suck out the grungy stuff a couple times until we're comfortable that we've gotten it out."

It is a tedious, complicated procedure that can cause more damage if not done right, he said, pointing out excessive delays could impede the blood flow.

"We don't want to occlude (stop) the blood flow longer than a few minutes because the heart is starving for blood."

The entire procedure totals about half an hour, with removal of the debris taking three to six minutes, Ho said.

Duncan said he was "kind of amazed" when Ho told him about the extra protection. He said he is walking two miles a day now and back to cutting the grass, "but not as aggressively as I used to."

Ho said Medtronic's Percu-Surge system, approved a year ago by the Food and Drug Administration, is not foolproof but cuts risk of debris stopping blood flow about 50 percent.

Clinical trials with the system showed 57 percent reduction in deaths and 42 percent reduction in heart attacks, Medtronic reports.

"The data is so good, it's almost a mandate to use it in bypass grafts," Ho said.

An interventional cardiologist must do five cases with the system to be certified to use it without Medtronic's supervision, he said. Ho's lab, certified last October, has done 15 or more cases, he said.

Some cases also have been done at St. Francis and Tripler Army Medical Centers, according to Medtronic.

With more than 1,000 heart bypasses done in Hawaii annually, the number of repeated vein graft blockages is substantial, Ho said.

Referring to the baby boomers, he said: "I suspect the volume will continue to increase as people age, and we will do more bypasses.

"Our goal is to get everybody on board with this device so the procedure is safer."

Kaiser has five cardiologists, including a new interventional cardiologist being trained by Ho in the distal protection system.

Another interventional cardiologist will join the group at the end of the year and be trained in the procedure, he said.

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