Pacemakers

A pacemaker is a small device used to treat some arrhythmias. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Pacemakers send electrical pulses to help your heart beat at a normal rate and rhythm. Pacemakers can also be used to help your heart chambers beat in sync so your heart can pump blood more efficiently to your body. This may be needed if you have heart failure. 

You may need a temporary (short-term) or permanent (long-term) pacemaker. A temporary pacemaker is normally inserted through a vein in the neck and remains outside your body. A permanent pacemaker is placed in your chest or abdomen. This topic focuses on permanent pacemakers. 

To get a pacemaker, you may need to stay in the hospital for a few hours or overnight. Once you are back home, your doctor may check your pacemaker remotely and schedule regular visits with you to check its activity. 

Many people with pacemakers can return to their regular activities within a few days. You may need to avoid certain electrical devices or devices that have strong magnetic fields. 

How they work

Traditional transvenous pacemakers

Traditional pacemakers (also called transvenous pacemakers) have three main parts. 

• A pulse generator creates the electrical pulses. 
• Wires (also called leads) are implanted inside the veins and carry the pulses to your heart. 
• Electrodes sense your natural heartbeat. When your heartbeat is slower than normal, the electrodes deliver electrical impulses to your heart to make it beat normally. 

The device can send data to your doctor remotely. Your doctor will use these recordings to set up your pacemaker so it works better for you.

A traditional pacemaker generator is placed outside of your heart, either in your chest or abdomen. It is connected via wires to electrodes inside one to three heart chambers. 

Single- and double-lead pacemakers send pulses to the right side of the heart. A biventricular pacemaker sends pulses to both ventricles and an atrium. The pulses help coordinate electrical signaling between the two ventricles to help your heart pump blood. This type of pacemaker is also called a cardiac resynchronization therapy (CRT) device. 

Wireless pacemakers

Wireless, or leadless, pacemakers are smaller than traditional types (about the size of a large pill capsule). The pulse generator and electrodes are all in one device that is placed inside a chamber of your heart through a small tube inserted in one of your veins. No surgery is needed. Once in place, the pacemaker then sends pulses to the right ventricle. 

Your doctor may recommend a wireless pacemaker if you have a slow heartbeat, or if you have an electrical block, which is when the flow of electricity to the heart is delayed between the upper and lower chambers of your heart. Depending on the type, this kind of pacemaker may sense the right atrium (upper chamber), which allows it to match the signals that it sends to the ventricle. This helps the two chambers beat in sync.

Other types of pacemakers

In another type of pacemaker, the electrodes are placed on the surface of your heart rather than inside your heart. This type of pacemaker requires surgery. 

Doctors also treat life threatening arrhythmias with a similar device called an implantable cardioverter defibrillator (ICD). The device constantly tracks your heart rate. If your heart shows an irregular and very fast rhythm, the ICD delivers an electric shock to reset your heart rhythm to prevent sudden cardiac arrest.

Who Needs Them

Pacemakers are used to treat certain types of arrhythmias, as well as heart failure, a condition that occurs when the heart cannot pump enough blood to the body. Not everyone with an arrhythmia needs a pacemaker.

Pacemaker for arrhythmias

The most common reason people get a pacemaker is their heart beats too slowly (called bradycardia), or it pauses, causing fainting spells or other symptoms. In some cases, the pacemaker may also be used to prevent or treat a heartbeat that is too fast (tachycardia) or irregular.

These problems may be caused by: 

• Problems with electrical signaling in your heart 
• Beta blockers, which are medicines to lower blood pressure but also can slow your heartbeat too much. A pacemaker helps prevent a slow heartbeat when you need to keep taking this medicine. 
• Certain congenital heart defects 
• Heart attack
• Heart transplant

Pacemakers for a weak heart

Pacemakers may also be used to help your heart chambers beat in sync if your heart isn’t pumping enough blood to your body. This can happen because of: 

• Certain congenital heart defects 
• Enlarged or thick heart muscle that makes it harder to pump blood out of your ventricles.
• Heart attack 
• Heart failure

What to Expect

The procedure may be planned ahead of time, or it may be done during an emergency (temporary pacemaker). You will be given medicine to make parts of your body numb or make you sleep during the procedure. 

You may receive antibiotics to prevent infection and blood thinning medicine to prevent blood clots during the procedure. Different types of pacemakers require different procedures to place them. 

Wired transvenous pacemakers

Many traditional, and all temporary, pacemakers are transvenous pacemakers, meaning the wires and electrodes are threaded through your veins. A doctor will thread the electrodes and wires through the veins in your neck, chest, or thigh, to the chambers of your heart. The electrodes are put in your heart muscle. The doctor may use echocardiography or X-ray to guide the process. 

Once the wires are in place, your doctor will make a small cut into the skin of your chest or abdomen. He or she will slip the device with the generator just under the skin, then connect it to the wires that lead to your heart. Your doctor will test to see if it the device works properly and then sew the cut up. The entire surgery may take up to a few hours.

You probably will not be allowed to move your arm for at least 12 hours after the procedure. This will help prevent disturbing the lead and the device and let your chest heal. 

Epicardial pacemakers

With epicardial pacemakers, the electrodes are attached to the surface of the heart rather than inside its chambers. This is a surgical procedure done under general anesthesia. Your doctor will make a cut below your ribs or armpit to place the pacemaker. Epicardial pacemakers are used as a standard precaution during heart surgery. 

They may also be used: 

• When a vein is blocked by a blood clot or plaque 
• When it would be difficult to insert the wires inside your heart chamber because of the structure of your heart or veins 
• When they are needed by newborns or children, who are the most common users 
• If you have a heart infection 

Wireless pacemakers

Wireless pacemakers are a newer type of pacemaker. The pulse generator and electrodes are all in one small device that is placed inside the heart. 

A doctor will thread a tube (called a catheter) through a vein in your thigh up to your heart. The catheter moves the pacemaker using X-ray images to place it in a heart chamber. 

The procedure often takes less than an hour, and you may be able to leave the hospital the same day. Typically, the recovery time is faster and the risk of infection is lower. The battery life of the device is between 8 and 13 years. 

Source: https://www.nhlbi.nih.gov/health/pacemakers

LINKS

• https://www.mayoclinic.org/tests-procedures/pacemaker/about/pac-20384689
• https://my.clevelandclinic.org/health/treatments/17360-permanent-pacemaker
• https://medlineplus.gov/ency/article/007369.htm
• https://www.bhf.org.uk/informationsupport/treatments/pacemakers
• https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/pacemaker-insertion
• https://www.nhs.uk/conditions/pacemaker-implantation/
• https://www.healthline.com/health/heart-pacemaker
• https://www.heart.org/en/health-topics/arrhythmia/prevention–treatment-of-arrhythmia/pacemaker