Generality
The pacemaker is an electronic device that is implanted in the body to normalize a heart rhythm altered by particular diseases or heart disorders, such as bradycardia, heart failure or atrial fibrillation.
The procedure for implanting a pacemaker in the body is quite simple and low risk; furthermore, it does not require special preparation, except for complete fasting and post-intervention assistance by a family member.
Short recall: normal heart rhythm and arrhythmias
The heart is an organ formed by a muscle, called myocardium, which has the peculiar ability to generate and conduct impulses for the contraction of the atria and the ventricles. The source (or generator) of these impulses, comparable to electrical signals, is found at the level of the right atrium of the heart and is known as the atrial sinus node .
The atrial sinus node has the task of marking the right frequency of contraction of the heart, in such a way as to guarantee a normal heart rhythm (also called sinus rhythm ), of 60-100 beats per minute, and a correct blood supply.
A cardiac arrhythmia is an alteration of the sinus rhythm, due to which the latter can assume a slower, faster or irregular frequency. The onset of an arrhythmia influences the contraction of the myocardium and the distribution of blood towards the various organs of the body, generally causing shortness of breath, sense of fatigue, syncope, fainting and confusion.
What is a pacemaker?
A pacemaker (the Italian translation of which is a marker ) is a small electronic device that, once connected to a heart that is too slow, too fast or irregular, normalizes the contractions, generating adequate electrical impulses.
HOW IS A PACEMAKER MADE?
A classic pacemaker is composed of a pulse generator and one or more leads .
- The pulse generator emits electrical signals for adjusting and maintaining the right heart rate. It is powered by a battery and is stored inside a small metal container.
- Leads are the metal connections that, by joining the heart to the pulse generator, allow electrical signals to reach their destination.
In addition, many current pacemakers have a sensory system that senses the movements of an individual and communicates them to the pulse generator, for an appropriate change in heart rhythm. This allows the carriers of these devices to freely perform certain physical activities, during which, for physiological reasons, the number of contractions of the heart and the respiratory rate vary.
TYPES OF PACEMAKERS
Depending on the number and where the leads join the heart, a pacemaker can be single chamber, bicameral or biventricular.
| Main features of single-chamber, bicameral and biventricular pacemakers. | |||
| Single chamber pacemaker | Dual chamber pacemaker | Biventricular pacemaker | |
| Features | It has a single lead connected either to the right atrium or to the right ventricle. | It is equipped with two leads, one connected to the right atrium and one connected to the right ventricle. | It is equipped with three leads, one attached to the right atrium, one to the right ventricle and one to the left ventricle. |
Because it is installed
A pacemaker is installed to restore the rhythm of a sick heart, which beats too slowly or irregularly.
If cardiac disorders are transient and reversible, with short-term treatment, this device may represent a temporary solution ( temporary pacemaker ); vice versa, if heart diseases are long lasting and require constant treatment, the marker is a permanent solution ( permanent pacemaker ).
In this article, the attentions are directed to permanent pacemakers, therefore only the pathological conditions and the use modalities concerning this type of solution will be described in detail.
Some examples of situations that require a temporary pacemaker:
- Late effects of a heart attack
- Late effects of heart surgery
- Overdose of drugs with bradycardia effects (ie that slow down the heart rate)
PATHOLOGICAL CONDITIONS REQUIRING A PERMANENT PACEMAKER
A permanent pacemaker can be installed to limit the symptoms and complications of the following pathological conditions:
- Bradycardia . It is an alteration of the heart rhythm characterized by a marked reduction in the number of beats per minute. The heart of a bradycardic patient, in fact, hardly reaches 50 contractions per minute. Bradycardia is typical of advanced age, as it is due to the aging of the muscle tissue that constitutes the myocardium.
- Heart failure (or heart failure) . It is a serious clinical condition, which can be determined by various factors (for example hypertension) and is characterized by a reduced cardiac output (NB: cardiac output is the volume of blood expelled by the ventricles, when they contract). Patients with heart failure experience shortness of breath, fatigue, tachycardia (high heart rate), ankle swelling, etc.
- Diseases of the atrial sinus node . They are anomalies that affect the atrial sinus node, which is the natural generator of cardiac electrical impulses. In these circumstances, the rate at which the heart beats becomes slower.
- Long QT syndrome . It is a disease characterized by irregular conduction of electrical impulses that stimulate the myocardium. People with this disease are prone to syncope and an increased heart rate (tachycardia).
- Atrial fibrillation . It is an arrhythmia that is located at the level of the atria and that makes the heart rhythm very rapid and irregular. The characteristic symptoms are palpitation, vertigo, syncope and shortness of breath. Possible complications, even fatal ones, are linked to a severe reduction in cardiac output.
- Atrioventricular block . As you can guess from the name, it is caused by an interruption between the atrium and the ventricle, electrical signals that contract the heart. This results in a lack of synchrony between the various cardiac cavities.
Preparation for the Intervention
What exams must be taken before surgery?
To determine whether or not a pacemaker is installed, the cardiologist submits the cardiac patient (ie heart patient) to a whole series of tests, including electrocardiogram, echocardiogram, cardiac holter and exercise test. These diagnostic tests are used to outline the health conditions of the cardiac organ, and the severity of the ailments in progress.
ELECTROCARDIOGRAM
The electrocardiogram ( ECG ) measures the electrical activity of the heart through the application, on the chest and on the limbs, of some electrodes. From the recording of how the signal for cardiac contraction is conducted, the cardiologist is able to find the presence of alterations of the sinus rhythm.
The ECG is a fairly simple exam, does not require special preparation, is not invasive and provides a fairly clear idea of the origin of the heart disorder.
ECHOCARDIOGRAM
The echocardiogram is an ultrasound examination that describes, in detail, the anatomy of the heart. The test therefore allows the identification of heart valve defects, myocardial malformations, cardiac output problems, etc.
Echocardiogram, like ECG, is a simple and non-invasive exam.
CARDIAC HOLTER
The cardiac holter, also known as Holter cardiac electrocardiogram, works like a normal ECG, with the only difference being that the patient's monitoring lasts for 24-48 hours, without interruption.
This investigation is particularly useful when arrhythmias occur sporadically.
NB during the entire execution of the cardiac Holter, the patient is invited to note on which occasions and after which activities the symptoms of the heart disease afflicting him appear.
EFFORT TEST
The exercise test is an evaluation of how an individual's heart works during a physical activity.
It provides that, during a very simple exercise test, some vital parameters are measured, such as heart rate, blood pressure and breathing.
How do you prepare for surgery?
Pacemaker surgery is performed under local anesthesia .
This means that the patient:
- On the day of the operation, he presents himself to complete fast since at least the previous evening.
This precautionary measure is adopted because, in the event of complications related to the intervention, it allows immediate recourse to general anesthesia (for which one must absolutely be on an empty stomach).
- At the time of your resignation, be returned home with a relative or a trusted friend.
The use of anesthetics slows reflexes and is a cause of confusion, therefore it could be dangerous to drive or not be assisted in case of special needs.
Failure to observe these precautions obliges medical personnel and the operating surgeon to postpone the procedure on another occasion.
NB: complete fasting means abstention from both solid foods and beverages (except for water, which can be taken up to a couple of hours before surgery).
Procedure
The installation of a pacemaker is a relatively simple surgery, which lasts 30 to 90 minutes and takes place with the conscious patient.
The area of the body that is anesthetized is located at the level of the clavicle and just below it: here, in fact, the leads (to be connected to the pacemaker) and the actual pacemaker will be inserted.
Once the various connections have been made, programming of the electronic device is provided, which basically consists in establishing how the newly implanted pulse generator must work.
After programming, the patient is kept under observation for a whole day (ie 24 hours); therefore, resignations generally take place the day after the intervention.
ANESTHESIA AND SEDATION
As anticipated, anesthesia is local; therefore, the anesthetic drugs are injected at the point where the leads and the pacemaker will be inserted.
Once anesthesia has occurred, the administration of sedatives begins, which serve to calm the patient and facilitate the entire procedure. Sedation drugs are injected through a needle-cannula, inserted into a vein in the arm.
INSERTION OF ELECTROCATETERS
Leads are the thin metal wires, about 50-60 centimeters long, that connect the heart to the electrical pulse generator.
Their introduction occurs in one of the large veins that pass near the clavicle (usually the brachiocephalic vein or the external jugular vein ) and requires extreme caution.
To be able to direct them to the correct destination (ie the heart), they must bring with them a contrast liquid, visible to X-rays.
NB: the number of leads and the precise location to reach depend on the type of pacemaker used.
INSTALLATION OF THE PACEMAKER
The metal casing containing the pulse generator (in fact, the most representative part of a pacemaker) must be inserted a little lower than the clavicle, by means of a subcutaneous incision .
Its installation takes place after the introduction of the leads, to which it must be properly connected.
Almost rectangular in shape, it measures about 3-4 centimeters, generally weighs 20-21 grams and has a battery life of 7-8 years.
What to do in case of intense pain?
The subcutaneous incision, in the first days after the operation, can be painful.
If the sensation is particularly marked, it is possible to take painkillers, such as ibuprofen or paracetamol .
PROGRAMMING OF THE PACEMAKER
Once the leads and the metal container have been installed and connected, the pacemaker must be programmed .
The programming is performed using a special computerized instrument and depends on the heart problem that afflicts the patient.
Once set, the pulse generator should be checked periodically to see if it is working properly.
Deepening: "rate-responsive" programming
In the past, pacemakers normalized heart rhythm without giving the heart any physiological variation. This prevented the patient from performing any physical activity, even the most moderate.
Today, medical technology has made great strides, allowing the creation of intelligent, self-programmable pacemakers also based on the physiological changes caused by physical activity and movement (for example: the increase in the respiratory rate, the raising of the heart rate and increase in blood temperature).
This type of setting is called "rate-responsive" programming, or frequency response programming .
RESIGNATION
Discharges usually take place the day after the operation, as the first 24 hours are essential to understand if the pacemaker has been programmed correctly.
During hospitalization, the patient is monitored in his vital parameters (heart rate, blood pressure etc.) and assisted in case of any need.
POST-INTERVENTION PRECAUTIONS
Some electronic instruments, such as mobile phones or appliances, and some medical diagnostic procedures, such as nuclear magnetic resonance or radiotherapy, can interfere with the pacemaker and alter its functioning.
Therefore, it is good practice:
- Avoid placing the mobile phone near the pacemaker;
- Communicate, before each electromagnetic diagnostic test or before the start of a radiotherapy treatment, of being a carrier of a pacemaker;
- Avoid approaching the microwave oven, refrigerator, television, electric razor, etc. too frequently and / or frequently.
Moreover, in the first 30 days after the operation, it is advisable to avoid excessive efforts, such as lifting weights.
The metal detector
The metal detectors of airports and shops, while not interfering with the pacemaker, warn of their presence and trigger the alarm connected to them.
To avoid these annoying situations, it is good to communicate your condition to security personnel and to undergo alternative checks.
Results
Current pacemakers are very effective devices, which generally work according to the intended purposes.
Moreover, following the precautionary measures illustrated by the cardiologist and going periodically to the controls of the device, it is possible to prevent most of the malfunctions.
WHAT TO DO IN CASE OF BATTERY EXHAUST?
A pacemaker battery typically lasts 7-8 years; after which it must be changed.
The change requires an even simpler and faster surgical intervention of the system described above, as the only essential operation is to replace the old battery with a new one. The electrodes and the metal container of the pacemaker, in fact, can remain the same.
risks
What risks do you run with a pacemaker implant?
The implantation of a pacemaker is a fairly safe procedure. However, like any surgical operation, it can hide pitfalls and result in:
- Infections of various kinds, at the point where the pacemaker is inserted.
- Allergic reactions to contrast fluid or anesthetic drugs used during the procedure.
- Damage to blood vessels, crossed by leads, or nerves placed near the pacemaker.
- A lung collapse .
- Myocardial hemorrhagic lesions, caused by the housing of the leads. In these situations, action must be taken immediately, stopping the wound and draining the spilled blood.
- Swellings, hematomas and bleeding, at the level of where the pacemaker is located.
