What is a Pacemaker - Doctablet

What is a Pacemaker, Functions, Implantation and Different Types

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Arrhythmia, Cardiology

Pacemakers are designed to treat the heart when it develops dangerously slow heart rhythms, regardless of the cause. The technology behind pacemakers has advanced significantly since it was initially developed in the 1950s. The function of the original pacemaker was to deliver a tiny, regular electrical impulse to the heart muscle that would allow it to beat at a normal rate so it could keep up with the body’s demands. The first pacemakers were rudimentary, performing mostly this basic function and little else. Modern pacemakers do much more than this.

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What can Pacemakers Do?

  • Sense the heart’s own pacemaker signal and deliver it to the ventricle in a timely manner to create or replicate optimal heart beat.

  • Turn itself off and just listen to the heart’s function, only kicking in if it is needed

  • Sense your physical activity with an accelerometer, and speed up the heart to keep up with your demands.

  • Identify arrhythmias and modify its functions to adjust to them

Modern devices can also communicate wirelessly to a control center, where any abnormal activity can be monitored.
The parts that make up a pacemaker

Depending on what the body needs, a pacemaker can last up to twenty years inside the body, although most pacemakers last an average of ten years. Battery life is constantly monitored by the doctor that cares for your device. There are four main companies that make pacemakers are Medtronic, Boston Scientific, Biotronic and Saint Jude. All pacemakers offer similar capabilities, but it is important you know what brand of pacemaker you have, as this will be important every time your device needs to be interrogated.

Pacemaker Surgery Incition

How a Pacemaker is Implanted

Pacemakers are implanted inside the body with surgery. The surgery is considered minimal and requires only conscious sedation rather than general anesthesia. Most pacemakers are implanted in less than an hour. The device is usually placed underneath the skin on the upper left side of the chest. To do this, a small incision about two inches is made in the area, and a pocket is carved between the muscle and the skin. From there, the cephalic vein is usually accessed. The cephalic vein is one of the major veins of the shoulder responsible for collecting blood from the arm and delivering it to the heart. The wires from the pacemaker are threaded into this vein all the way into the heart. Once in the heart, the wires are screwed into the heart muscle. Most pacemakers have two wires that reach the heart: one that tracks the activity of the atrium, and another one that reaches the ventricles and delivers an electrical pulse to them.  The most important risks related to getting a pacemaker are infection, hematoma formation within the pocket created to implant the device, and perforation of the heart muscle. 

After a Pacemaker is Placed

After a pacemaker is placed, the person can experience discomfort and mild swelling in the area. This is not unusual and usually resolves after a week. It is advised you avoid lifting the left arm above your shoulder for one month after surgery to allow the device to heal and settle into the body.  It is important you set up regular follow-up with a pacemaker center after your pacemaker has been placed. This is usually set up for you before you leave the hospital after your surgery, but it can also be done at your doctor or cardiologist’s office, depending on what is available. Once your incision is healed, you will be set up with a remote pacemaker monitoring service. Once you have become comfortable with the device, the machine is fully automatic and requires little attention. A card will be provided to you to carry that identifies you as having a permanent pacemaker in case a security check requires it. Today, most pacemakers are MRI-compatible and suffer no interference from other electrical devices, like microwave ovens or computers.

Special Pacemakers Available Today

Lead-less Pacemakers

Pacemaker technology has advanced today to allow for devices that are small enough to be implanted directly into the heart without the need for wires. These devices are an option for elderly patients who are at higher risks of complications related to standard pacemaker implantation because of conditions like diabetes, peripheral vascular disease, renal disease requiring dialysis and chronic skin infections. Once in, these devices cannot be taken out of the heart, so they remain an option only for older patients. Yet, even while incredibly small, their battery has the capacity to pace the heart for eight to ten years, and if necessary, up to four additional devices can be placed within the right ventricle.  The Medtronic Micra is an example of such a device currently available on the American market. The Micra can be implanted using a minimally invasive approach through the groin in a procedure that takes fifteen to twenty minutes to complete.
Lead-less Pacemaker Size

Cardiac Resynchronization Therapy Pacemakers

Another significant advance in the world of pacemakers is the use of what is known as cardiac resynchronization (CRT) devices. Rather than simply pace the heart, CRT pacemakers help coordinate the contraction of the two ventricles so they occur simultaneously rather than apart. Discordant cardiac contraction, a situation where the ventricles squeeze with different timing from one another, is caused by conditions like heart failure, cardiomyopathy and advanced conduction disease. The restoration of coordinated ventricular contraction these devices offer has the potential to improve heart failure symptoms and reduce the mortality associated with heart failure.  Resynchronization is achieved by the implantation of an additional wire in the left ventricle. With this wire in place, the pacemaker can deliver an electrical impulse to both lower chambers at once, making them contract at the same time.
Cardiac Resynchronization Animation
About the Authors
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Jose Taveras M.D. F.A.C.C.

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Dr Taveras works as a cardiologist caring for spanish speaking communities in the Bronx. He completed a dual residency in Internal Medicine and Pediatrics and then served as chief resident of internal medicine at the St. Vincent’s Catholic Medical Center of New York. He went on to specialize in cardiovascular disease at NYU Winthrop Hospital , under the mentorship of Dr. Kevin Marzo, chief of Cardiology at Winthrop. He is board certified in both internal medicine and cardiovascular diseases, and sub specializes in echocardiography, nuclear cardiology and computed tomography of the heart. Apart from his work in community outreach, Dr. Taveras' career focuses on innovation and technology. Dr. Taveras is a fellow of the American College of Cardiology. 

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Jorge Romero M.D. F.A.C.C. F.H.R.S.

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Jorge Romero, MD, is an Attending Physician and Assistant Professor of Medicine in the Arrhythmia Service of the Cardiology Division at the MontefioreEinstein Center for Vascular Care. He specializes in the treatment of complex arrhythmias, particularly in catheter ablation of ventricular tachycardia and atrial fibrillation using cutting-edge technology. Dr. Romero is a member of the American Heart Association (AHA), and a fellow of the Heart Rhythm Society (FHRS) and the American College of Cardiology (FACC).

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