Gaining a Better Understanding of Pacemakers and Defibrillators

Pacemakers and defibrillators have become so common. Everyone has questions and concerns about these. Here are some frequently asked questions and answers.

What are pacemakers and defibrillators used for?

Pacemakers are used when the heart rate is too slow or stops and the patient is symptomatic: dizziness or blackouts usually. Conversely, defibrillators are for the opposite: The heart is racing and in cardiac arrest. The defibrillator shocks the heart into rhythm. These are installed in survivors of cardiac arrest, or with weak hearts more likely to have a cardiac arrest (an ejection fraction less than 30%) or with familial or other disposition for sudden cardiac death.

So pacemakers beat at a constant rate?

Most times, no. Most pacemakers will have a lead in the right upper chamber (atrium) and one in the right lower (ventricle). If the patient has a normal rhythm and only needs the pacemaker sometimes, the pacer senses this. It can track the atrium and raise the rate in response to the atrium.

What about defibrillators? Can they pace?

Most defibrillators will have a backup pacing function that can beat about 40 beats per minute. In some patients with a normal conducting system who need shock only in the event of a cardiac arrest, there are subcutaneous (under the skin) defibrillators that will only shock, no pacing. In patients who also need pacing for a slow heartbeat, some will have two-lead pacemakers incorporated in them.

What are three-lead pacemakers/defibrillators?

Three-lead, or biventricular, pacemakers are pacemakers placed in patients with a weak heart and a left bundle branch block (a conduction problem on EKG). In these patients, besides the heart being weak, it is also dyssynchronous; one side of the left ventricle gets current a fraction before the other. This pacemaker will help with this.

BIO: Dr. Kollagunta Chandrasekhar, better known as Dr. Sekhar (pronounced Shaker) has been practicing cardiology in Winter Haven for 20 years. Dr. Sekhar is the Chief of Sta at Bay Care Winter Haven Hospital as well as the Director of the Heart Function Clinic and the Cardiac Rehabilitation program at Bay Care Winter Haven Hospital and the Chairman of Cardiology at Advent Hospital in Lake Wales. He is a member of the Heart Failure Society of America, the American Heart Association, the American College of Physicians, and the American Society of Nuclear Cardiology. To schedule an appointment, please call (863) 508-1101.

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