Zapping the Heart Back Into Rhythm

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Source: University of Michigan Health System

Zapping the Heart Back Into Rhythm

Description

If the electrical system in your house was going haywire, you’d call an

electrician right away to fix it. But what if the electrical system in your

heart was on the fritz?

Newswise — If the electrical system in your house was going haywire, you’d call

an electrician right away to fix it.

But what if the electrical system in your heart was on the fritz?

For 2.3 million Americans whose hearts beat too fast or don’t keep a regular

rhythm, the answer is usually medicines and occasional electric shocks. But

these can cause serious side effects and lose their power over time. That leaves

many patients with an irregular heartbeat that saps their strength and raises

their risk of having a stroke.

Now, a new option offered at the University of Michigan Cardiovascular Center

and a handful of other centers nationwide is proving to be a true, lasting cure

for the vast majority of people who receive it.

Called catheter ablation, the approach has cured more than 1,000 U-M patients

who have the most common form of irregular heart rhythm, called atrial

fibrillation or AF, and allowed them to return to an active life. U-M doctors

have cured 85 percent of patients with the kind of AF that comes and goes on its

own. And even patients whose hearts beat irregularly all the time can be cured

about 75 percent of the time.

Just like a house’s electrical wires, the heart has a system of nerves that use

a constant flow of electricity to control the pumping action of the heart’s

muscular walls. Normally, this keeps the heartbeat regular. But in atrial

fibrillation, it goes haywire — often because of other heart problems, but

sometimes for no apparent reason. Patients can feel weak or short of breath, and

lose their strength.

Now, just like an electrician looks inside a house’s walls to find the wires

that are causing a problem, U-M heart specialists can look into the heart’s

walls and find the source of a rhythm problem. Then, they “zap” tiny areas of

the heart muscle with intense radio waves, blocking the flow of electricity and

restoring a normal rhythm.

The catheter ablation technique doesn’t involve surgery, but rather a system of

tiny wires that are fed into the heart through a major blood vessel. Patients

only need a mild sedative, and go home from the hospital the next day.

U-M doctors are considered world leaders in catheter ablation for AF, with more

successfully treated patients than most centers. U-M doctors have also performed

research that shows how well the technique works and how it can be improved.

Fred Morady, M.D., leads the U-M catheter ablation team. “There are many

patients who don’t respond to medications or can’t tolerate them. In the last

few years, we’ve had the option of catheter ablation to cure their atrial

fibrillation,” he says.

Morady is the McKay Professor of Cardiovascular Diseases and directs the

Clinical Electrophysiology Service at the U-M Health System. He and other U-M

cardiologists have trained many other doctors to perform the technique so it can

be available to even more patients.

There’s a great need for more doctors who can perform catheter ablation, Morady

says. Atrial fibrillation is diagnosed in 160,000 more Americans each year, and

the number of people living with the condition is expected to double in the next

few decades as the Baby Boomer generation ages.

As people age, Morady explains, many factors can cause the heart’s electrical

system to go on the fritz and cause a rapid or irregular heartbeat. “Atrial

fibrillation is often a result of some other type of heart problem, such as high

blood pressure, problems with the mitral valve, and sometimes excessive thyroid

hormone levels,” he says. “There are also a fair number of patients who develop

it as purely an electrical problem with the heart, without any other evidence of

structural problems with the heart.” People who are overweight, or who have

breathing problems when they sleep are also at higher risk of developing atrial

fibrillation.

No matter what the cause, AF can make a person’s life miserable, keeping them

from participating in activities or working because of weakness, dizziness,

shortness of breath and less endurance. Then again, some people with AF have a

mild form of the condition and don’t know it.

Unlike other less common heart rhythm problems, AF doesn’t pose a risk of

killing a person directly. But because it keeps the heart from pumping blood

efficiently, blood clots can form in the chambers of the heart and travel to the

brain, causing a stroke that can kill or cause permanent disability. In fact, as

many as 15 percent of all strokes occur in people with AF.

In addition to disability and stroke, AF can lead to heart failure, because a

heart that beats too fast for many months without being controlled can become

weakened and enlarged.

Drugs that keep the heart’s rhythm steady, or keep it from beating too fast when

its rhythm gets out off kilter, can help decrease symptoms. Blood-thinning drugs

can prevent blood clots from forming. And cardioversion, or an electric shock to

the chest, can “re-set” the heart rate. But many patients get less and less

relief, and more and more side effects, from the various drugs as time goes on.

And cardioversion’s effects may only last a few months.

That’s why catheter ablation is such an exciting option, says Morady — its

effects are permanent. And unlike open-heart surgical options that have been

used on some AF patients in the past, catheter ablation only requires a small

incision in the groin, to insert the wires (or catheter) into the blood vessel

that leads to the heart. Then, an X-ray machine takes real-time pictures as the

doctor threads the catheter up to the heart, through the heart’s outer muscle,

and through the wall that separates the two upper chambers of the heart — the

left atrium and right atrium. Patients have a sedative that allows them to

remain awake but groggy, and keeps them from remembering the experience.

“We use the wires to map out the electrical circuits of the heart, and then to

deliver radiofrequency energy to destroy some of the areas that are causing the

atrial fibrillation,” Morady explains.

This “zapping” of small patches of heart muscle heats up an area the size of a

pea, effectively burning the muscle tissue so it can’t conduct electricity.

“Everywhere that we find a spot, the energy heats the tissue and destroys that

small area. We typically have to burn 40 to 60 spots before the AF resolves,” he

says. Many of those spots are in the area where the veins that bring blood from

the lungs enter the heart, but others are on the walls of the atrium itself.

The U-M team customizes the treatment to each patient’s individual electrical

situation, and the entire procedure takes about three hours. Sometimes, patients

need to return for a second treatment, or need to receive a single cardioversion

shock to permanently eliminate their AF.

In all, Morady says, there’s still a need for research on how well catheter

ablation compares with long-term drug therapy in reducing larger risks — and the

procedure isn’t yet recommended for people who are still keeping their heart

rhythm under control with medication. But the importance of this new option for

atrial fibrillation is growing, and is sure to grow as doctors gain more

experienced and achieve higher success rates, and new doctors learn the

technique.

One patient’s catheter ablation success story:

Jerry of Fort Wayne, Indiana had tried many medications in his three-year

struggle with atrial fibrillation. The condition had first made itself known to

him when he was out deer hunting in the fall of 2001, and was helping a friend

carry his prize back to the truck. All of a sudden, he felt like he couldn’t

catch his breath and had to stop. Later that day, his wife took him to the

emergency room, thinking he had had a heart attack.

“They put me on a medicine which would slow my heart down to a regular, normal

heartbeat, and they also told me that in a certain amount of time my body would

get immune to that and my heart would go back out of rhythm. And that’s exactly

what happened,” he says. Even stronger medication and cardioversion shocks

didn’t help.

Just as was resigning himself to a life of inactivity at the age of 67, a

young cardiologist who had trained at U-M heard about his case. He referred him

to Morady, who agreed he was a good candidate for catheter ablation. After two

procedures and one cardioversion in late 2004, he’s completely symptom-free and

back in action — and praising U-M’s care.

“What amazed me about Dr. Morady was that he took time to walk you through each

procedure,” says. “He’s one of the best doctors I think I’ve ever met.”

Facts about atrial fibrillation and catheter ablation:

• At least 2.3 million Americans have atrial fibrillation, the most common form

of heart rhythm irregularity, and 160,000 more are diagnosed each year. The

number of people living with AF is expected to double in the next three decades

as the Baby Boomer generation ages.

• AF occurs when there are problems with the electrical system in the muscle of

the heart’s upper chambers, or atria. This can cause the heart to beat too fast,

or in an irregular pattern.

• Although AF doesn’t kill, it can cause weakness and shortness of breath

because the heart can’t pump blood very well. It can also cause blood clots to

form and travel to the brain, causing a stroke. People with atrial fibrillation

have five times the normal risk of stroke.

• Typical treatments for AF include medications to prevent problems with heart

rhythm, to prevent blood clots from forming, or to slow down the heart rate of a

person while their rhythm is off. Cardioversion, or electric shocks, can also be

used to re-set heart rhythm. But none of these treatments is a cure, and all of

them can lose effectiveness over time.

• Catheter ablation is a minimally invasive technique that can cure many AF

patients who are no longer helped by medications or can’t take AF medications.

It delivers tiny but powerful jolts of radiofrequency energy to the wall of the

heart, blocking the flow of electricity.

Find out more on the web at:

U-M Health Topics A to Z:

Atrial fibrillation http://www.med.umich.edu/1libr/aha/aha_atfibril_car.htm

Options for the treatment of atrial fibrillation

http://www.med.umich.edu/1libr/aha/Pt_ed_A1204.pdf

American Heart Association: Arrhythmias:

http://www.americanheart.org/presenter.jhtml?identifier=8