What is it about ?
The heart consists of a left atrium, a right atrium, a left ventricle, and a right ventricle. These cavities are separated by partitions. Blood enters the heart through the atria. The ventricles eject blood into the body.
The heart works autonomously, that is, it beats without intervention on our part. The heart muscle (myocardium) contracts under the effect of an electrical stimulation (stimulus). This stimulus is created in a node of nerves called the sinus node, located in the heart wall of the right atrium. This sinus node is the natural pacemaker. From the sinus node, current travels to the heart muscle through a special electrical conduction system. Thus, the electrical impulses pass through the entire myocardium. These impulses stimulate this muscle, which contracts.
Normally, this is done on a regular basis, at a rate of between 60 and 100 beats per minute (rhythm or heart rate) while resting.
The pacemaker records the heartbeat and gives impulses when the rate drops below a certain threshold. The pacemaker consists of two parts:
- the pulse generator which is implanted under the skin of the chest, just below the left collarbone;
- electrodes that are introduced into the heart through a vein.
There are different types of pacemakers that can be programmed in different ways. Some pacemakers register body movements or breathing and adapt the frequency of stimulation to physical activity.
In whom is it indicated to implant a pacemaker?
It is indicated to implant a pacemaker in case of:
- too slow heartbeat with symptoms (bradycardia symptomatic): the main reason for implanting a permanent pacemaker is the presence of specific elements demonstrating a relationship between a slow heart rate and symptoms (dizziness, fainting). It is important to rule out other causes of a slow heart rate first and treat them if necessary.
- impairment of the conduction node located in the atria (sinus node dysfunction): heartbeat too slow, with symptoms of dizziness, fainting or heart failure, or insufficient heart response during exertion.
- disruption of conduction from the atria to the ventricles (atrioventricular block).
The type of stimulation (stimulus) is chosen based on the symptoms and examinations described below. Either the atria alone are stimulated, or the ventricles alone, or the atria and ventricles at the same time. The goal is to prevent cardiac arrest
How does the doctor decide whether it is appropriate to have a pacemaker implanted in you?
The doctor begins by listening carefully to your symptoms. THE’electrocardiogram (ECG) is the main tool for detecting cardiac electrical conduction disorders. The ECG can be observed at a distance for a period of time or during a stress test. These examinations are carried out in the hospital by a cardiologist. Most often, it is not necessary to perform an invasive examination.
How is the follow-up of a patient who wears a pacemaker?
This follow-up is mainly carried out by the cardiologist. A check-up is carried out a few months after implantation, then every year or every two years. The doctor then performs an ECG, and reads and interprets the pacemaker’s memory. It also checks the battery life; the normal lifespan is 7-8 years.
If you find that the heart rate is too slow, contact the cardiologist. This may be because the battery is getting low. The doctor will then check if the electrodes are still working correctly, and he will determine the stimulation threshold. The stimulation threshold is the minimum energy required to generate a heartbeat. If the threshold is increased, it may be because the tip of the electrode has moved or because scar tissue has grown around it. The doctor will also monitor the remaining electrical activity of the heart itself.
When is an additional check-up or an emergency appointment necessary?
In the following cases:
- bleeding at the site of the procedure;
- shortness of breath, possible consequence of pneumothorax;
- contractions of the muscles of the diaphragm or around the pulse generator;
- pain around the pulse generator;
- signs of infection (redness, warmth) around the pulse generator;
- dizziness or loss of consciousness recurring;
- ECG abnormalities that indicate a disturbance in pacemaker function.
What instruments interfere with a pacemaker?
Pacemakers are equipped with an internal security system against external interference. This system is activated when the device detects strong external influences.
Mobile phones and electrical devices in the home or office have no effect on the operation of the pacemaker. However, it can be affected during an examination or operation in the hospital. For example, MRI and ultra-short wave therapy should be avoided.
You should also take precautionary measures during an operation; it is better to check the pacemaker after the procedure.
How is the pacemaker removed?
Pacemakers are generally not reused. After death, they must be removed before the funeral and properly disposed of (small hazardous waste). Especially for incineration, it is important to remove the pacemaker as the battery can explode when heated. In some cases, the data stored in memory is used to determine the cause of death.
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