Types of pacemakers

There are several types of medical devices for maintaining heart rate. All of them perform the main function - the preservation of the physiological work of the heart. Each of the pacemakers has its own characteristics of functioning. When the heart rhythm is disturbed, the device sends an electric charge to the muscle, which restores the required heart rate. If the organ is working normally, the ECS controls it, but for any violations it instantly works, correcting the pathological condition.

Consider the main types of pacemakers :

• Temporary - used when urgent heart rhythm correction is needed (acute myocardial infarction, bradycardia, tachyarrhythmia). Necessary for the diagnosis of the heart, as well as in the preoperative period.
• Outdoor - refers to the temporary, used to correct heart rhythms for various indications. The design of this device consists of three-dimensional electrodes that are placed on the chest and the cardiac projection area (between the spine and the left scapula). Suitable for the diagnosis of disease state and as a preventive measure.
• Implantable - a miniature device with titanium or any other alloy inert to the body. Implanted in the subclavian region under the pectoralis major muscle. The operation is performed under local anesthesia, and the electrodes are led to the chambers of the heart through the subclavian vein.
• Single-chamber - one of the most common types of pacemakers with a single electrode in the heart ventricle. The first models worked only at a given frequency of reductions. While modern devices are focused on changing heart rate with such a need.
• Two-chamber - consists of two electrodes, which are placed in the ventricle and atrium. This creates a physiological synchronous contraction of the heart chambers. This type of EX-is considered the most comfortable for patients, compared to single-chamber.
• Three and four-chamber - stimulate a given sequence of heart chambers. They provide physiological intracardiac hemodynamics and eliminate the desynchrony of the heart chambers in severe pathologies.

In addition to the above classification, devices are divided by functionality:

• Pacemakers - set the heart right rhythm.
• Cardioverter defibrillators - set the rhythm, stop arrhythmia attacks and perform ventricular fibrillation.

Devices vary in cost. The more modern the model, the higher its price. There are such price categories:

• Imported models with many functions, usually three and four-chamber, wireless. Provide a full lifestyle. But because of the increased energy consumption, they have a shorter lifetime.
• The best option for the criterion of price and quality. Most often these are two-chamber and latest single-chamber POS versions.
• Outdated models are distinguished by their reliability and relatively low cost. Lose in their functionality, comfort of use and appearance.

The choice of the optimal pacemaker option is done by the doctor together with the patient. The doctor selects the model of the device, guided not only by medical indications, but also by the capabilities and wishes of the patient.

Single-chamber pacemaker

An artificial heart rate driver with an active electrode that stimulates only one organ chamber (ventricle or atrium) is a single-chamber pacemaker. The device is quite simple and has several varieties:

• Frequency-adaptive - automatically increases the frequency during exercise.
• Without frequency adaptation - the stimulation is carried out with a constantly set frequency.

The main disadvantage of this device is that the atrium retains its rhythm, while the contractions of the ventricle and the atrium may not coincide. Because of this, blood from the ventricle is thrown into the atrium and blood vessels. That is, the device does not provide a consistent work of the ventricle and atrium.

The main indication for the installation of the mechanism is the stimulation of the right ventricle:

• Permanent atrial fibrillation.
• Sick sinus syndrome.

During implantation, the electrode can be installed both in the left and in the right ventricle. But today single-chamber devices are limited in use, since there are more modern models with enhanced functionality.

In addition, even the simplest dual-chamber EKS can operate in single-chamber stimulation mode. As for the cost of a single-chamber device, the simplest model will cost about $ 200, and more modern ones from $ 500.

Dual-chamber pacemaker

A device that perceives and stimulates two chambers of the heart, both with and without frequency-adaptive adaptation, is a two-chamber pacemaker. One electrode is inserted into the cavity of the atrium, and the second into the right ventricle. Due to this, all blood pumping units are stimulated, ensuring consistent work and correct blood flow in the heart.

Bifocal pacing is of the following types:

• Atrioventricular - endocardial electrodes are installed in the right atrium and right ventricle.
• Biatrial - one electrode is inserted into the right atrial appendage, and the second is required for synchronized electrical stimulation of the left atrium, in the coronary sinus.

The main difference between the two-chamber apparatus and its predecessor, the single-chamber apparatus, is that when the atrial and ventricle contractions coincide, the injection of blood into the atrium and blood vessels is excluded. The ECS aligns and controls atrial and ventricular rhythms, setting the natural rhythm of contractions — first the atria, then the ventricles.

Also note that the device operates in DDDR or DDR mode. That is, the device changes not only the frequency of rhythm-driving, but also the duration of the delay in AB contractions. ECS provides a complete filling of blood vessels, even in violation of the conductive functions of the body.

The main indications for dual chamber pacemaker:

• Bradycardia with a pulse lower than 40 beats per minute.
• Morgagni-Adam-Stokes syndrome.
• AV blockade 2 and 3 degrees.
• Incomplete blockades.
• Syndrome of a carotid sine.
• Severe violations of the contractile function of the myocardium during physical activity.
• Pathologies with a decrease and an increase in heart rate.
• Chronotropic incompetence (insufficient increase in heart rate during exercise and excessive reduction at rest).

In addition to the above indications, the device is implanted if necessary, additional functions, for example, recording electrocardiography. The device allows you to lead a full active lifestyle with a minimum of contraindications. But it should be noted that the additional set of functions leads to a rapid discharge of the battery EX. At the price of the device is 1.5-2 times more expensive than single-chamber.

[1], [2], [3], [4], [5], [6]

Three-chamber pacemakers

The latest generation of EKSs that stimulate the three sections of the heart in a specific sequence are three-chamber pacemakers. The device provides physiological movement of blood through the chambers of the body.

The device consists of three electrodes, one is mounted in the atrium, and the other two in the left and right ventricle. Due to this, cardioresynchronization occurs, which creates a normal movement of blood in all parts of the heart. The device is able to work in single and dual-chamber stimulation.

Indications for use:

• Violation (resynchronization) of cardiac activity.
• Dysynchrony of cardiac chambers in bradyarrhythmia or severe bradycardia.
• Rigid sinus rhythm caused by the depletion of the reserves of the organ.

As a rule, three-chamber devices have a touch sensor and partial adaptation functions. Sensors collect information on respiratory rate, nervous system activity and body temperature. Analysis of the data allows you to choose the optimal mode of operation of the device. The cost of the device depends on its manufacturer and functionality. In comparison with previous generations of EKS, three-chamber mechanisms have the highest price.

Temporary pacemaker

One of the treatment-and-prophylactic methods for preventing deaths due to a heart rhythm disorder is wearing a temporary pacemaker. External artificial pacemaker is installed by resuscitator in such cases:

• Arrhythmia.
• Absolute blockade.
• Slow heart rate in combination with fainting.
• Myocardial infarction.
• Ventricular tachycardias on the background of bradycardia and other life-threatening pathologies.

Temporary cardiac rhythm stimulation is not performed in the absence of good venous access, with hemorrhagic diathesis and anticoagulant therapy.

The device is installed in the ambulance carriage or in intensive care. During the introduction of a temporary pacemaker, the doctor places a catheter in the peripheral vein, providing monitoring conditions for cardiopulmonary resuscitation. The electrode is inserted through the internal jugular or subclavian vein.

After the patient's condition returns to normal, a comprehensive examination of the body is carried out and, if indicated, implantation of a permanent pacemaker is performed.

Pacemaker Defibrillator

An EX with a function to detect and eliminate ventricular fibrillation is an implantable pacemaker, a defibrillator (ICD).

The main indications for the use of ICD:

• Life threatening arrhythmia.
• Heart attacks damaging the electrical system of the heart.
• Sudden cardiac arrest in history and the risk of its recurrence.
• Congenital heart defects.
• Long QT syndrome.
• Brugada syndrome.

The device saves lives, as in 5% of cases, ventricular fibrillation without electropulse treatment is fatal. That is, the device starts the heart when it stops and normalizes the heart rate.

Pacemaker Defibrillator Operation Principle

The feature of the artificial pacemaker with defibrillatory functions is that the device controls heartbeats and, if necessary, normalizes them. ECS has wires with electrodes that are inserted into the heart chambers. The device gives electrical signals that allow you to track heart rate.

If an arrhythmia is fixed, then low-energy discharges occur, normalizing the work of the organ. The rhythm is restored and the device operates in monitoring mode. High-energy pulses can cause pain.

External pacemaker

An external device designed to prevent deaths is an external pacemaker. The device is installed at the termination of the heart or life-threatening slowing of the heart rate.

The device is necessary in case of blockages of a temporary nature, acute myocardial infarction with transient cardiac rhythm and conduction disturbances, as well as overdose with drugs.

External EKS has volume electrodes with high resistance. They are placed on the anterior and posterior chest wall. The device gives long high-amplitude pulses - 20-40 ms to 200 mA. This procedure of stimulation of the heart is quite painful in comparison with the endocardial, but allows you to avoid infectious complications, thrombosis and bleeding, pneumothorax or heart perforation.

[7], [8], [9], [10], [11], [12], [13]

Wireless pacemaker

In 2016, the FDA approved the serial production of the world's first wireless pacemaker Micra. The device was developed by Medtronic and is a real breakthrough in the management of patients with heart disease.

Artificial heart rate driver allows you to control any violations. The mechanism is placed directly in the heart, but without any additional wires. Implantation is carried out through the femoral artery into the right ventricle of the organ. The Micra installation takes about 30 minutes and the battery is replaced without surgery.

Indications for device installation:

• Atrial fibrillation.
• Atrial fibrillation.
• Bradycardia-tachycardia syndrome.

The device is absolutely safe for patients, but nevertheless there is a risk of complications: EX-bias, heart attack, deep vein thrombosis of the lower extremities, pulmonary embolism and more. These complications occurred in 7% of patients and required hospitalization for further treatment.

Despite all the advantages of this device, there are contraindications for its installation. Wireless EXs are not implanted if there are other devices in the body that may affect the operation of the device. The device is not placed if the patient's veins cannot accommodate a 7.8 mm guide housing. Contraindications include obesity, individual intolerance to heparin anticoagulants and the materials from which the instrument case is made.