Arrhythmia, an irregular heartbeat, can be a serious problem or just a nuisance. Precise diagnosis, including electrophysiology (EP) studies, is key to determining if and how to treat the problem. For serious cases, implantable devices or radiofrequency ablation can mean the difference between life and death.

Rene Valentin occasionally has a sharp pain in his chest that he says feels "almost like gunshots." But it is a "friendly fire" of sorts: A tiny implanted defibrillator, programmed to shock his racing heart back to a regular rhythm, has done its job.

The 63-year-old man's struggle with arrhythmia-an irregular heartbeat-reached a dramatic peak in July 2000. He had a heart attack while driving his truck, crashing it into a pillar at the Newark train station. The heart attack induced sudden cardiac death, in which the heart develops a potentially lethal arrhythmia. Fortunately for the Newark man, he spontaneously came out of the arrhythmia and was taken to University Hospital.

Doctors believed that there was a strong possibility that Mr. Valentin could experience another such episode, but the next time not be as lucky. So, an implantable cardioverter defibrillator (ICD)was placed in Mr. Valentin's heart. Similar to a pacemaker, a battery-operated ICD contains a microprocessor and leads that monitor and record heart rate.

Implantable cardioverter defibrillators (ICD) can deliver potentially life-saving electrical shocks to counteract lethal arrhythmias.

"When the heart is beating abnormally-either too fast or too slow-the goal is to get it back to normal sinus rhythm as quickly as possible," says Dr. Joaquim Correia, director of arrhythmia services at The New Jersey Cardiovascular Institute (NJCI) at University Hospital and Mr. Valentin's cardiologist. "The ICD continuously monitors the heart's rhythm, and it delivers potentially life-saving electrical shocks when the rate reaches a pre-programmed level."

Mr. Valentin's ICD has "fired" a few times, leading doctors to perform two angioplasty procedures to open narrow arteries. However, today, he says he feels well and maintains a positive outlook. "I do a lot of walking, take my medicine, and follow the doctor's orders," says Mr. Valentin, who works for the Union City Parking Authority. "And I don't worry."

When the Heart's Electrical System "Misfires"

Normally, electrical impulses pass through the heart, causing it to contract and pump blood to other parts of the body. When this complex system is damaged or "misfires," it is known as arrhythmia: the heart works too hard, not efficiently enough, or skips a beat. These irregular heartbeats run the gamut in severity, from life-threatening, leading to sudden cardiac death, to those that are merely a "nuisance."

The most common form of arrhythmia, affecting more than 2 million people each year, is atrial fibrillation.

Two general categories of arrhythmia are bradycardia-the heart is beating too slow-and tachycardia, when the heart beats too quickly. Frequently, the arrhythmia is identified by where it originates in the heart. For example, an atrial tachycardia refers to rapid electrical impulses that begin in the heart's upper chambers. The most common form of arrhythmia, affecting more than 2 million people each year, is atrial fibrillation. Atrial fibrillation is a type of supraventricular tachycardia, in which chaotic electrical activity causes the atria to quiver rapidly.

Symptoms of arrhythmia include heart palpitations, which are described by patients in various ways-a fluttering in the chest, skipping a beat, or a pounding in the chest; dizziness; fainting spells; and shortness of breath. Sometimes, however, arrhythmias don't cause any unusual feelings.

Arrhythmia in the Young and Physically Fit

The largest group at risk for arrhythmia is the most obvious: people with existing heart conditions. And as people age, they face a greater likelihood of developing an irregular heartbeat. But arrhythmia can and does occur in younger people, sometimes causing sudden cardiac death.

Arrhythmia can be part of another condition, such as Wolff-Parkinson-White Syndrome or Inherited Long QT Syndrome. With WPW, a type of pre-excitation syndrome, an otherwise healthy person has an extra electrical pathway from the atria to the ventricles. Long QT Syndrome occurs when the time the heart takes to "recharge" after each beat is longer than normal. Unfortunately, both of these conditions can cause arrhythmia (although some WPW patients don't have this symptom) and go undetected until there is a sudden cardiac death.

However, there are important clues that can bring these conditions to light before tragedy strikes. Some WPW patients experience the typical symptoms of arrhythmia, such as palpitations and dizziness. Fainting and a family history of unexplained sudden death of a young person are two other risk indicators. Tilt-table testing in the electrophysiology lab can help determine the cause of fainting. The patient, whose heart rate and rhythm and blood pressure are constantly monitored and recorded during the procedure, is secured onto the table. The table is set at different positions until the patient is standing upright at a 70-80 degree angle; sometimes a medicine is administered by IV to make the patient's heart rate increase.

Ironically, young athletes-those who are in good physical condition-can also develop arrhythmia, particularly bradycardia, as a better conditioned heart beats more slowly. Sudden cardiac death is very rare in athletes (about 1:200,000), but the fact that it occurs has resulted in recommendations being issued by the American Heart Association. Generally, they call for high school and college competitive athletes to have a pre-participation cardiac screening every two years. Further evaluation, including stress testing and an ECG, would be conducted if problems such as chest pain, dizzy spells, and palpitations were discovered.

Sleuthing by Wire

There are several tests that are used to diagnosis arrhythmia. An electrocardiogram creates an image of the heart and how it pumps. Patients may be asked to wear a recording Holter monitor for a short period of time, typically 24 hours. Even then, there's no guarantee that an arrhythmic episode will occur when the monitor is being worn. Under the controlled environment of an electrophysiology lab, arrhythmias can be "triggered" and then "mapped," providing the physician with valuable information from which to make a diagnosis and a treatment plan.

Electrophysiology is a specialized field that studies the relationship of the body's function (in this case, the heart) to its electrical system. During an electrophysiology study, the patient is given a local anesthetic, and electrode catheters are fed through a small opening in the groin or neck to the heart. The heart's electrical impulses are recorded and mapped. The electrophysiologist can "pace" the heart to evoke an arrhythmia episode.

New Alternatives for Arrhythmia

Once an arrhythmia is diagnosed, says Dr. Correia, medication is often the first course of treatment. "While they are helpful for many patients, some of these drugs have significant side effects, such as thyroid and liver abnormalities. Others, like calcium channel blockers, can cause constipation and low blood pressure," he says. "And quinidine, one of the older drugs, can result in some people having a shorter life span, but a better quality of life during that time. It's not a choice doctors like to make." Sometimes, a patient's arrhythmia cannot be well controlled by medication.

During the 1980s, pacemakers and ICDs emerged as valuable alternatives to medication. And yet today, "they've undergone a huge transformation," notes Dr. Correia. "These devices, which used to be as large as a deck of cards, are now smaller than a matchbook. We have dual-chamber pacemakers and rate-responsive pacing defibrillators, the latter which can be set to 'overdrive,' making the heart go a little faster to see if it will then adjust back to a slower rhythm on its own. This results in fewer 'shocks.'"

The surgical techniques have kept pace with the technology, as well. The traditional, "open" surgery to implant a defibrillator was often hard on the patient, requiring a hospital stay of five to seven days. Today, electrophysiologists can insert an ICD through the skin in under an hour; arrhythmia is induced under controlled conditions to test if the defibrillator is working as programmed. The patient, who is given a local anesthetic, is typically walking around an hour after the surgery and can go home that day. People who have ICDs sometimes have mixed feelings about the device. On one hand, should their heart reach the rate where the defibrillator is activated, they will receive electrical shocks. On the other hand, they have immediate, potentially life-saving treatment. "When someone comments about the pain, I'm sympathetic, but I also say, 'Look, you're here,'" says Dr. Correia.

A Permanent Cure

There's another option for some arrhythmia patients, one that is up to 95 percent effective: radiofrequency ablation. The word ablation means "elimination," and that's what this technique does to tissue involved in certain types of arrhythmia. As with an electrophysiology study, radiofrequency ablation involves the threading of electrode catheters, guided by fluoroscopy, into the heart. The electrophysiologist "maps" the electrical signals and determines where the offending tissue is located. Then, radiofrequency energy is directed to that precise spot, destroying the tissue.

"Usually, the best news a doctor can deliver to a patient is, 'You have an illness that we can't cure. But we can prescribe medicine that you'll have to take for the rest of your life," says Dr. Correia. "With radiofrequency ablation, the arrhythmia goes away and never comes back."

Radiofrequency ablation currently is used to treat ventricular tachycardia, AV nodal reentry tachycardia, supraventricular tachycardia, and atrial flutter, and shows promise for the treatment of atrial fibrillation. It has also proven effective for patients with Wolff-Parkinson-White Syndrome. The patient's piece of additional tissue can be destroyed using radiofrequency ablation, never to reoccur.

"I performed this technique on a WPW patient who has since moved away from our area," recalls Dr. Correia. "Every year around the holidays, she sends me something clever-usually something with a wolf on it-to remind us both that her 'Wolff' is gone forever."

For more information, contact the New Jersey Cardiovascular Institute at (973) 972-5742 or click on: www.TheUniversityHospital.com/njci.