DR. ZIAD ISSA: Despite the prevalence of heart disease, many patients are living longer thanks to advancements in new technology. Today, more than two million Americans rely on a pacemaker or defibrillator to regulate their heart beat. As the patient population continues to increase, many questions have surfaced from patients and loved ones about implanted cardiac devices.
Q. When would a patient receive a pacemaker?
A. A normal heartbeat starts by an electrical signal generated by the heart's natural pacemaker, which is responsible for the regular, rhythmic heartbeat. The electrical signals travel via specialized electrical cables to stimulate the pumping chambers to beat. When the natural pacemaker fails to generate electrical signals at a normal rate or the electrical signals fail to reach the pumping chambers of the heart due to nonfunctioning electrical, a very slow heart rate can result and can cause a variety of symptoms. This includes lack of energy, easy fatigability, dizziness, or fainting. In these situations, implantation of an artificial cardiac pacemaker is required.
Q. When would a patient receive a defibrillator?
A. The heart's natural pacemaker is the only source of electrical signals in the normal heart. Occasionally, part of the pumping chambers of the heart acquire the ability to generate electrical signals which cause the heart to beat at a dangerously fast rate, causing dizziness, fainting, or even cardiac arrest and death. Defibrillators are implanted in patients who already experienced or are at risk of developing life-threatening fast heart rhythms.
Q. How do pacemakers and defibrillators work?
A. Pacemakers and defibrillators are small units; each contains a pulse generator, which houses a battery and a computer chip. The generator is placed in a pocket under the skin below the collarbone. The device is connected to the heart via thin flexible wires known as leads, which are advanced into the heart through veins.
Pacemakers are electronic clocks, which sense when the heart rate is slow and send a small electrical impulse (not felt by the patient) to stimulate the heart to beat. Defibrillators, in addition to having pacemaker capability, can also send high-energy electrical pulses (shocks that are usually felt by the patient) to stop dangerous fast heart rhythms.
Q. How long does a pacemaker or defibrillator last?
A. Pacemakers can last 6 to 12 years or more before battery depletion. Defibrillators last a few years shorter. When the battery is depleted, the old pulse generator is removed and a new one is connected to the already existing leads. In contrast, the leads of pacemakers and defibrillators can last for a longer time without the need for replacement. However, leads may occasionally malfunction or become infected, in which case new leads need to be implanted. The old leads may need to be removed in various cases including infection, malfunction, and if abandoned leads cause occlusion of the veins it is necessary to implant new leads.
Q. How are the leads removed?
A. Because scar tissue binds the lead within the heart and veins, lead extraction demands expertise and specialized tools to avoid serious complications. Prairie Cardiovascular Consultants is using laser-powered equipment to free the leads from the surrounding binding tissue and facilitate their removal.
Ziad F. Issa, M.D. is the clinical cardiac electrophysiologist at Prairie Cardiovascular Consultants, Prairie Heart Institute and St. John's Hospital. He serves as a clinical assistant professor at Southern Illinois University. Issa specializes in management of heart rhythm disorders. Patients interested in learning more about pacemakers and defibrillators can visit http://www.prairiecardiovascular.com or call 217-788-0706.
