Trial helping halt cardiac arrest

PeaceHealth takes part in test of implantable defibrillator less risky than traditional version

By Marissa Harshman, Columbian Health Reporter

Published:

 

Cardiac arrest is different than a heart attack.

Cardiac arrest occurs when irregular heart rhythms (too fast, too slow, chaotically) cause the heart to stop beating. Without medical attention, the person will die within a few minutes. People are less likely to die if they have early defibrillation, which sends an electric shock to restore the heart rhythm to normal.

Most heart attacks occur when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. That often leads to an irregular heartbeat that causes a severe decrease in the pumping function of the heart. A blockage not treated within a few hours causes the affected heart muscle to die.

Source: National Institutes of Health

The new implantable device was created by Dr. Gust Bardy and is now being manufactured by Boston Scientific.

During the trial, Dr. Robert Swenson, cardiologist at The Vancouver Clinic and president of the Heart and Vascular Center at PeaceHealth Southwest Medical Center, implanted the device in two patients and monitored them for about three years ago. Across the country, the study had about 130 participants, Swenson said.

Last year, the device was approved for routine use and should be available for widespread use this spring, Swenson said.

But while the manufacturer gears up production, a limited number of devices have been available. Since PeaceHealth Southwest was a part of the study, the cardiologists there have had access to the device in the interim, Swenson said.

In the past three months, Swenson has implanted six of the new devices in patients.

--Marissa Harshman

Cardiac arrest is different than a heart attack.

Cardiac arrest occurs when irregular heart rhythms (too fast, too slow, chaotically) cause the heart to stop beating. Without medical attention, the person will die within a few minutes. People are less likely to die if they have early defibrillation, which sends an electric shock to restore the heart rhythm to normal.

Most heart attacks occur when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. That often leads to an irregular heartbeat that causes a severe decrease in the pumping function of the heart. A blockage not treated within a few hours causes the affected heart muscle to die.

Source: National Institutes of Health

The new implantable device was created by Dr. Gust Bardy and is now being manufactured by Boston Scientific.

During the trial, Dr. Robert Swenson, cardiologist at The Vancouver Clinic and president of the Heart and Vascular Center at PeaceHealth Southwest Medical Center, implanted the device in two patients and monitored them for about three years ago. Across the country, the study had about 130 participants, Swenson said.

Last year, the device was approved for routine use and should be available for widespread use this spring, Swenson said.

But while the manufacturer gears up production, a limited number of devices have been available. Since PeaceHealth Southwest was a part of the study, the cardiologists there have had access to the device in the interim, Swenson said.

In the past three months, Swenson has implanted six of the new devices in patients.

–Marissa Harshman

The technology to prevent sudden cardiac arrest is evolving in Clark County.

PeaceHealth Southwest Medical Center is one of only a few dozen hospitals across the country that participated in a trial of a new implantable defibrillator. And by participating in the trial, PeaceHealth Southwest’s Heart and Vascular Center is among the first hospitals in the country to routinely offer the new device to patients.

The device, called S-ICD, delivers the same lifesaving shock as traditional implantable defibrillators but is not intravenous and doesn’t attach directly to the heart.

“It’s more like when you get paddles from a paramedic,” said Dr. Robert Swenson, cardiologist at The Vancouver Clinic and president of PeaceHealth Southwest’s Heart and Vascular Center.

Preventing cardiac arrest

Cardiac arrest occurs when irregular heart rhythms (too fast, too slow, chaotic) cause the heart to stop beating.

Most people who experience cardiac arrest won’t survive, Swenson said. In a county the size of Clark, one or two people die each day from cardiac arrest, he said.

Implantable defibrillators can help to prevent sudden cardiac arrest. Defibrillators monitor the heart for irregular rhythms. When one is detected, the defibrillator shocks the heart back to normal rhythm.

“When it does that, it hurts,” Swenson said. “But it saves lives.”

Traditional implantable defibrillators are placed in the chest, beneath the collarbone. The wires attached to the device run through the large vein along the collarbone and attach to the heart. The shock travels through those wires, directly shocking the heart.

The problem is, while durable, those plastic-covered metal wires occasionally need to be replaced. Removing them, however, is not easy because scar tissue forms between the wire and the vein, Swenson said. Pulling too hard can rip the vein open, he said.

Most often, cardiologists just run additional wires and leave the original in place, Swenson said.

Another risk with the traditional device, Swenson said, is the possibility of infection in the bloodstream. Since the wires run through a vein, it’s easy for bacteria on the wires to spread throughout the body via the bloodstream, he said.

The new implantable device reduces those risks, Swenson said.

Rather than being placed below the collarbone, the new device is implanted on the side of the chest, beneath the armpit. The wire runs beneath the skin to the bottom of the sternum. From there, the wire runs along the breast bone. The shock travels through the muscle to the heart rather than directly shocking the heart.

Since the wires don’t run through veins, they can be easily removed if an infection occurs, and they don’t carry the risk of infection spreading through the bloodstream, Swenson said.

The new devices, however, currently have a shorter lifespan than the traditional devices, Swenson said.

The current devices last about eight years, while the new devices only last about five years, Swenson said. Replacing the devices is a quick one-day procedure, he said.

Defibrillator implants

At PeaceHealth Southwest’s Heart and Vascular Center, cardiologists implant about 30 defibrillators each month.

“The vast majority of those are those who haven’t had cardiac arrest,” Swenson said.

Most patients who receive defibrillators have had previous heart attacks or have other heart disease that has caused damage to the heart, Swenson said. People who show other signs of electrical abnormalities in the heart are also good candidates for defibrillators, he said.

Ridgefield resident Ken Schrecengost, 76, had a defibrillator implanted last fall, a year and a half after a major heart attack.

In February 2012, Schrecengost woke up to an unusual feeling in his chest. He took some ibuprofen, and later some Pepto-Bismol, before heading to Longview, where he works as the oral health coordinator at Lower Columbia College Head Start.

After working several hours with the odd feeling in his chest, Schrecengost called his physician’s office. They told him to get to an emergency room immediately. He was flown via helicopter to Oregon Health and Science University in Portland, where he was rushed into a cath lab. There, a cardiologist inserted a balloon stent to open a severely clogged artery.

The prolonged time of blocked blood flow concerned Schrecengost. He wondered how much heart muscle had been damaged.

Initially, it didn’t appear too damaged. But during a follow-up visit six months later, Schrecengost learned his heart attack had reduced his heart’s ability to pump blood. That, Swenson told him, put him at much higher risk for sudden cardiac arrest.

In October 2013, Schrecengost had the new device implanted.

“You hope it never goes off,” he said. But since nearly 95 percent of people who experience cardiac arrest without a defibrillator die, Schrecengost is glad he has the device, should he need it.

“It’s a very good protective device,” he said.

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