March 2, 2000 (Atlanta) -- Pacemakers and defibrillators already allow some people with serious heart disease to climb mountains and run marathons. Experts say such implanted devices will become even more advanced in the next decade, becoming smaller and more responsive -- perhaps even sounding alarms to warn of dangerous heart rhythms.
Both kinds of devices can help patients manage irregularities in the electrical circuitry of the heart known as arrhythmias. "Arrhythmias are common and can either be too slow or too fast," says Paul Walter, MD, director of pacemaker and arrhythmia services at the Emory Clinic and professor of cardiology at Emory University School of Medicine in Atlanta.
Abnormal heart rhythms often go unnoticed, but can cause dizziness, fainting, or palpitations, which are sensations of the heart beating forcefully or irregularly in the chest. "Pacemakers are prescribed for slow and irregular heartbeats," Walter says. "They're designed to sense interruptions in rhythm and deliver precisely timed electrical impulses for a more normal heartbeat."
Walter says pacemaker technology is continually evolving. "Pacemakers of the future will be more responsive to muscle activity and have more memory," he says. "They might also include alarm systems to warn patients of dangerous rhythms, which could be extremely important in the prevention of strokes."
Manufacturers say these and other enhancements are likely within the next 10 years.
"Responsiveness to muscle activity and breathing will continue to improve with every generation of the device," says Dan Schaber, vice president of bradyarrhythmia therapy at Medtronic Inc. Enhancements in the devices' memory, he says, mean they will eventually be able to provide physicians with patients' yearly average heart rates, to aid medical decision-making.
Wally Strauss, MD, 73, a retired internist, tells WebMD that a progressively low heartbeat would have ended his life were it not for the pacemaker he received in 1994. "I was terribly fatigued when my heart rate dropped to the thirties," he says "But my pacemaker allows me to be hyperactive. In fact, I'm training to climb Mt. Kosciusko in Australia this spring."
Heart rhythms that are too fast can also be managed with implanted devices, experts say. Implantable defibrillators give a small electric shock to the heart when the heart rhythm becomes dangerously fast or irregular.
"Fast rhythms can sometimes cause an abrupt loss of heart function or sudden cardiac arrest," says Gary Lubben, vice president of ventricular tachyarrhythmia therapy at Medtronic. "And because survivors are at risk for future episodes, an implanted defibrillator is like having an emergency room in the chest."
Lubben tells WebMD that the latest models are the size of a pager and can be implanted without opening the chest cavity. The new generation of defibrillators can also carry out some of the regulating functions of a pacemaker.
Dennis Halsey, a 50-year-old mechanical engineer, had a defibrillator implanted after having a sudden cardiac arrest during a basketball game. "Luckily, I was resuscitated by a teammate who specializes in emergency medicine," he says. "Doctors don't know what caused it and it can happen again. So they implanted a defibrillator just in case."
Halsey tells WebMD that he now runs up to 1,500 miles per year. "After the heart attack, I got serious about running and have since competed in five marathons." Halsey, who has a best time of three hours and 52 minutes, says, "The defibrillator has given me the freedom to do what I want to do without medications. And I feel a whole lot safer, too."
Experts say pacemakers might someday be used to treat cardiac disorders other than arrhythmias. "The new devices can pace different areas of the heart simultaneously," says Schaber. "And this could prove to be particularly helpful in managing congestive heart failure." Walter tells WebMD that clinical trials to study this have already begun.
British cardiologists envision even smarter implanted devices someday. "Pacemakers that can direct an ambulance to a symptomatic patient could become a reality in the next century," says Richard Vincent, MD, a professor of cardiology at Sussex University in Brighton.
At the British Association Science Festival last fall, Vincent said that voice recognition in pacemakers could be another valuable enhancement. "What I envision is something like a learning phase at first," says Vincent. "Then the device would optimize pacemaking for routine activities in response to verbal cues."
Biomedical engineers applaud the concept, but doubt it will become reality in the near future. "The concept of voice recognition in pacemaker technology has a lot of merit," says Mike English, a research engineer at Sussex University. "But voice transmission through the skin is technically complex and probably a ways off."
- Today's pacemakers are implanted devices that help maintain a normal heartbeat in patients who have irregular heart rhythms. Restoring a regular heart rhythm can help people stay active and live a normal life. In some extreme cases, pacemakers allow once-weakened patients in otherwise good condition to do things such as run marathons.
- Someday, pacemakers may be able to orchestrate a rhythm in different regions of the heart at the same time, which could treat diseases like heart failure. This application is being studied now.
- Future pacemakers might be able to react to a person's muscle activity and warn of harmful rhythms. Eventually, the devices might even be able to recognize the user's voice and summon an ambulance.