Cardiac Pacemaker, Types and Operation

A pacemaker is an electronic device designed to solve certain cardiac rhythm problems by generating electrical impulses capable of stimulating and producing the contractions of the heart according to the needs of the patient whose autonomic cardiac impulse generation system is damaged by different causes. The pacemaker consists of a metal casing little larger than a wristwatch, containing complex electronic circuits and a battery (generator), and one or more electrodes (wires) which, from the generator, reach the inside of the heart through veins and transmit the impulses generated inside the casing to the heart.

Cardiac problems that require the placement of a pacemaker

In general, pacemakers are indicated for cardiac rhythm disorders that produce an abnormal decrease in heart rate, and there are two main causes: Dysfunction of the sinus node (where cardiac impulses originate) producing absence or decrease of beats, or failure in the conduction of impulses to the cardiac muscle. Additionally, some atrial arrhythmias with slow ventricular response can produce cardiac symptoms that resolve with the placement of a pacemaker. Finally, there are arrhythmias that produce a very fast heart rate. In such cases, a part of the autonomic conduction system can be “burned” to prevent tachycardia, after implantation of a pacemaker to ensure contraction of the ventricles.

Pacemakers, risks and complications

Early complications are very rare. At the time of pacemaker insertion, arterial and venous lacerations, pneumothorax and ventricular perforation with or without cardiac tamponade can occur, with an incidence of less than 1%. Later, dislocation of an electrode may occur, requiring repositioning, thrombosis of the veins in the arm, and wound problems, the most important of which is infection, requiring removal of the system. These later complications are also very rare.

Duration of a pacemaker

Depending on the type of pacemaker installed, and the patient’s need for it, the average life span of pacemakers varies between approximately 6 and 11 years: On the one hand, more sophisticated pacemakers generally consume more energy and their battery lasts less time. On the other hand, if all the beats are produced by the pacemaker stimulus (the patient does not produce beats spontaneously), the battery will obviously run out sooner. Once it is detected that the remaining life of the pacemaker is less than 3-4 months in the controls carried out periodically by means of an external device to the pacemaker itself, it is indicated to change the generator, which is done electively, and consists of surgically exposing the device under local anesthesia, disconnecting the generator from the electrode, and connecting a new generator to the same electrode, closing the wound when it is verified that the system is working correctly.

Read Now 👉  The Importance of Anticoagulation Therapy Control in Artificial Heart Valves

Pacemaker placement

As mentioned above, when a type of arrhythmia susceptible to treatment with a pacemaker is detected, it is essential to specify the type of device to be implanted in order to guarantee the most physiological functioning of the heart. Once the type of pacemaker has been decided, one or two electrodes with radioscopic control must be installed in the heart through the veins near the clavicle by means of a small incision under local anesthesia. Once the electrodes are installed, the electrical parameters of the electrodes are checked to ensure that they are adequate, they are connected to the generator and the surgical wound is closed.

Pacemaker, postoperative care

Before the intervention, coagulation should be normalized as far as possible (most patients requiring pacemakers are treated with anticoagulants or antiplatelet agents) to reduce hemorrhagic complications and wound hematomas that could be a problem by themselves and by suffering secondary infection. After implantation, patients should be reviewed on an outpatient basis to adapt the energy consumption of the pacemaker to the parameters analyzed with the external programmer/analyzer, and to prolong the life of the device as much as possible. The vast majority of patients with pacemakers resume normal activities within a week. However, they should avoid any rough physical contact with the pacemaker area as this may damage the lead or the device. Diathermy treatments, MRI scans (except in compatible models), and transurethral needle ablation should be avoided. In general, it is recommended that, before undergoing any clinical procedure, the specialist who is going to perform it should be informed that the patient has a pacemaker, since some procedures may affect the pacemaker’s functioning.

Finally, patients who have a pacemaker implanted should be provided with a “pacemaker patient guide” published by the Spanish Agency of Medicines and Health Products, which will clarify practically all their doubts.