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What is a Pacemaker, and how does it work?


A pacemaker is an electrical medical device usually the size of a matchbox. A surgeon implants it under the skin to help control irregular heartbeats called arrhythmias. Doctors may also use pacemakers to treat some types of heart failure.

Usually, the electrical signal that makes the heart beat begins in an area of the heart called the sinoatrial (SA) node. The SA node is your heart`s natural pacemaker. The SA node generates the electrical signals from the top of the heart to the bottom in a synchronized manner leading to a heartbeat.

In certain instances, there are issues with this electrical signaling, which can lead to a heartbeat that is too fast (tachycardia), too slow (bradycardia), or irregular. This situation is an arrhythmia. A pacemaker generates electrical impulses that help your heart beat at a regular rate, rhythm, or both.

Next, we will discuss pacemakers, including different types, the implantation, and the associated risks.

Pacemaker Types

There are two parts to modern pacemakers: the pulse generator, which contains the pacemaker’s battery and the electronics that generate electrical signals, and one or more wire leads, which are thin cables that transmit electrical signals from the pulse generator to the heart.

The leads carry the pacemaker’s electrodes. The electrodes, which often rest inside your heart and detect your heartbeat, transmit electrical signals if the heart’s beating is too fast or too slow.

Traditional pacemakers usually have one or two leads. A single-lead pacemaker sends electrical signals to the heart’s right atrium or the right ventricle. A dual chamber pacemaker sends electrical signals to the heart’s right atrium and the right ventricle.

Some patients need a particular type of pacemaker called a biventricular pacemaker (bivent).

A biventricular pacemaker has three leads, which transmit electrical signals to the right atrium, right ventricle, and left ventricle, allowing the two sides of the heart to synchronize. The implantation of a biventricular pacemaker is known as cardiac resynchronization therapy (CRT).

There are also wireless pacemakers, and the implanting usually occurs in the right ventricle. In this pacemaker, the pulse generator and electrodes combine into a single device the size of a pill.

To prevent life-threatening arrhythmias, particularly heartbeats that are too fast and unstable, doctors may use an implantable cardioverter defibrillator (ICD). If an ICD detects arrhythmias, it transmits electrical impulses to restore a normal heartbeat. Newer ICDs also have a pacemaker function.


Candidates for a Pacemaker

A cardiologist or physician will examine you to see if you are a good candidate for a pacemaker. One of the main reasons to recommend a pacemaker is that a heartbeat is too slow. However, doctors also use pacemakers for heartbeats that stop, are irregular or too fast, and for some heart failures.

Various factors can cause those symptoms, such as age-related changes to the heart tissue, heart damage due to prior heart surgery, heart disease or a previous heart attack, congenital heart conditions, or taking medications that slow heart rate.

Besides, health issues include inflammation of the heart tissue (pericarditis), heart muscle (myocarditis), and cardiomyopathy, which involves heart muscle changes that affect blood pumping.

Some other rare conditions, such as causing inflammation and scarring of the skin and internal organs (systemic sclerosis), causing swollen areas of tissue to appear in the organs of the body (sarcoidosis), or hypothyroidism in which the thyroid produces too little thyroid hormone.

Some signs that an individual may have an arrhythmia or heart failure requiring a pacemaker are fatigue, dizziness or lightheadedness, heart palpitations, chest pain or tightness, and shortness of breath or fainting.

Not all pacemakers are permanent. Temporary pacemakers can manage particular types of problems. For example, you may require a temporary pacemaker following a heart attack or surgery. You may also need one if an overdose of medicines has temporarily slowed your heart.

Pediatric Pacemakers

Criteria for receiving a pacemaker are different for children than for adults. For example, many children with pacemakers have bradycardia, which causes disturbing symptoms. In addition, children with bradycardia often have a history of congenital heart conditions or have had heart surgery that has affected electrical signaling in the heart.

Risks Associated with a Pacemaker

Every medical procedure has risks. However, risks associated with a pacemaker generally result from the implantation procedure. These risks include an allergic reaction to anesthesia, bleeding, bruising, blood clots, damaged nerves or blood vessels, an infection at the incision or leads, and the buildup of scar tissue around the pacemaker.

Additionally, it may include the pacemaker syndrome, when a pacemaker stimulates only one ventricle, causing fatigue, breath shortness, low blood pressure, and pacemaker-related cardiomyopathy.

We can add the risk of a collapsed lung (pneumothorax), fluid collection around the heart, and displaced leads that can cause a punctured heart. Usually, complications are temporal, and life-altering complications are unusual.

It is also possible, although unlikely, for a pacemaker to malfunction or stop working correctly. This event can happen if, for example, one or more leads move out of position, the battery of the pulse generator runs out of power, a potent magnetic field damages your device, or there is a programming error with it.

If your pacemaker is malfunctioning, you may notice that your arrhythmia or heart failure symptoms begin to worsen. If this happens, it is crucial to make an appointment with your physician or cardiologist so they can verify to see if your pacemaker is working correctly.


Preparing for a Pacemaker

Before getting a pacemaker, you will need several tests which can ensure that a pacemaker is a suitable choice for you.

Among those tests, we find the electrocardiogram, placing sensors on your skin to measure your heart’s electrical signals, and the echocardiogram, using sound waves to measure the size and thickness of the heart muscle.

In addition, the Holter monitor tracks your heart rhythm for up to 48 hours, and the stress test monitors your heart rate while exercising.

Your physician or cardiologist will review the results of these tests, and your medical records, to conclude if a pacemaker is a suitable option for you. It is important to understand that not everybody with arrhythmia or heart failure needs a pacemaker.

For example, a cardiologist may not recommend a pacemaker if an arrhythmia is asymptomatic or occurs with only mild symptoms. Another example of when a pacemaker is unnecessary is when the symptoms are due to a reversible cause, such as infection or drug toxicity.

If a pacemaker is suitable for you, you will need to plan for surgery; essential factors to consider include fasting before your procedure; this means that you cannot eat or drink anything besides water six hours prior to the process or potentially longer.

Also, your doctor will instruct you about which medicines and supplements to take and not to take before the procedure and which soap you should use to reduce the chances of developing a potentially serious infection.

Finally, you will have to plan to wear comfortable, loose-fitting clothes on that day; you will have to change clothes for the hospital gown for surgery.

Pacemaker Surgery

Most lead pacemakers implantations are through a transvenous procedure, which means the doctors insert the leads and electrodes through your veins and into your heart. Usually, they use the veins in the neck, chest, or thigh.

Transvenous insertion often follows the next steps: first, you will take a sedative to relax and receive a local anesthetic to sedate the incision area; you will be awake during the procedure. Next, your surgeon makes a small incision, usually near your collarbone.

Then, they will guide the wire leads through the incision and into a primary vein. An x-ray will help them conduct the leads through the vein to your heart. Once the leads reach the heart, doctors will place the electrodes on your heart muscle. Then, they will connect the other end of the wire lead to the pulse generator that contains the battery and electrical circuits.

After the leads and electrodes are in place, the surgeon will implant the generator under the skin near the collarbone. At the end of the procedure, the surgeon will test the pacemaker to ensure it is working correctly before closing the incision with stitches.

Inserting a pacemaker in this manner generally takes about one hour. However, it can vary depending on the number of leads. For example, the placement of a biventricular pacemaker, which has three wire leads, usually takes longer than a placement of a single-lead pacemaker. But, again, the surgeon will let you know what to expect.

A less common way to implant a pacemaker is through the epicardial method, where electrodes attach to the surface of the heart instead of inside, requiring general anesthesia. For example, as a precaution during heart surgery, when the structure of the heart or veins makes it challenging to use the transvenous method, or when they place a pacemaker in an infant or child.

The insertion of wireless pacemakers goes through a thin tube called a catheter. Then, a live

x-ray machine guides the catheter and wireless pacemaker through a vein in the thigh to the heart. This process generally lasts less than one hour.

Before you go home, your physician will ensure the pacemaker’s programming is working correctly for your heart’s needs and may recommend a chest x-ray. The physician can reprogram the device as required at follow-up appointments.

You will probably feel pain or discomfort after the procedure and may need to take over-the-counter medications for relief.

It is also indispensable to make sure you take care of the incision at home. The surgeon will instruct you on how to clean the wound and prevent infection.

Most likely, you will return to your daily activities in the days following the placement of the pacemaker. However, it would help if you continued avoiding rigorous exercise for about six weeks, particularly raising the arm on the pacemaker’s side.

Because the pacemaker sends minimal electrical signals, you are unlikely to feel them, but if you do, the cardiologist can adjust the programming to minimize this. Also, as the pulse generator is under the skin, you may feel it when lying down in some positions.

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Modern Heart and Vascular, a preventive cardiology medical practice, has several offices around Houston. We have locations in Humble, Cleveland, The Woodlands, Katy, and Livingston.

We are Modern Heart and Vascular Institute, a diagnostic and preventative medicine cardiology practice.

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At the Modern Heart and Vascular Institute, we offer state-of-the-art cardiovascular care with innovative diagnostic tools and compassionate patient care. Our priority at Modern Heart and Vascular Institute is prevention. We help patients lead healthier lives by avoiding unnecessary procedures and surgeries.

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This article does not provide medical advice. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you need cardiovascular care, please call us at 832-644-8930.

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