What is a pacemaker check

Pacemaker

English: pacemaker or artificial cardiac pacemaker

1 definition

A Pacemaker is an implanted, electronic device that ensures a stable heart rate in patients with bradycardia. The device stimulates the myocardium with a current surge at a preset frequency of approx. 70 / min. Newer types of pacemakers can adapt the rate control to body activity (rate-adaptive pacemakers).

2 General

Within the conduction system of the heart there are so-called pacemaker cells in the sinus node. At rest, these normally cause the heart muscle to contract at around 60-80 beats per minute. Due to various circumstances it can happen that the conduction of the excitation of the sinus node is disturbed and the heart switches to the secondary pacemaker, the AV node. However, this only causes a contraction of approx. 40-50 beats per minute.

If this fails too, the heart switches to its tertiary pacemaker, the bundle of His. Here the frequency is even lower (approx. 20-40 beats / min). If the heart rate at rest is less than 60 beats per minute (adult, not athlete), the indication for the implantation of a pacemaker is given. Furthermore, newer pacemakers have the option of recording cardiac arrhythmias in the wearer (event recorder).

3 implanted (permanent) pacemaker

The device is usually implanted in a subcutaneous pocket caudal to the collarbone. The device is connected to probes located intracardially. Pacemakers are coded with the NBG code in order to make statements about their type and function.

The following must be given:

  • Stimulation location (A - atrium, V - ventricle, or D - double)
  • Sensing location (as with the stimulation location)
  • Operating mode (I - inhibition, T triggering or D - both)
  • Special function (R - rate modulation)

3.1 Stimulation and Sensing

According to this coding principle, one-chamber systems with stimulation and sensing in a cardiac cavity (e.g. VVI pacemaker, AAI pacemaker) can be distinguished from two-chamber systems (e.g. DDD pacemaker).

3.2 Operating mode

Two fundamentally different modes of operation are possible with a pacemaker:

  • Inhibition - The pacemaker controls the frequency by delivering impulses, but is inhibited in its impulse delivery in the case of the heart's own impulses.
  • Triggering - The pacemaker continuously emits impulses, even when the heart is performing its own action. Here, however, the pacemaker is programmed in such a way that the impulses emitted fall during the heart's own actions during the refractory period, i.e. do not hinder the self-action.

3.3 Rate adaptation

Rate adaptive pacemaker systems (e.g. VVI-R, DDD-R) can adapt the heart rate to physical stress. Here, physical activity is recorded by sensors for minute ventilation and body movements, and the pacemaker's stimulation frequency is increased.

3.4 Examples

4 transcutaneous pacemakers

External pacemakers are usually only used for a short time (max. A few days) and are used in patients with severe bradycardia to bridge the gap until a permanent pacemaker is implanted. The current surges occur here through a thicker layer of tissue and therefore require a higher current strength.

5 transvenous pacemaker

Here, an electrode is inserted into the heart through a central venous catheter and the myocardium is stimulated there. The frequency is controlled by an external stimulator. Like the transcutaneous pacemaker, this method is only selected temporarily, usually to bridge the gap until a permanent pacemaker is implanted.

6 epimyocardial pacemaker

An epimyocardial pacemaker is applied prophylactically during or after cardiac surgery (e.g. ACVB). The conduction system can be influenced and / or injured by the intervention.

7 implantable cardioverter defibrillator (ICD)

An implantable cardioverter defibrillator (ICD) is a defibrillator system that is implanted like a pacemaker. With a strong current surge, for example in the case of ventricular fibrillation, the heart can be brought into the starting rhythm by cardioversion or defibrillation.

Such devices are often incorrectly referred to as pacemakers. However, this is not the case, as the ICD is only used in an acutely life-threatening situation, such as ventricular fibrillation, ventricular flutter or PVT, and is not used to set the heart rate.

8 indications

The indication for pacemaker therapy must be made individually. In the case of bradycardias of various origins, bradycardia-related symptoms such as dizziness and syncope are important indications. Furthermore, pauses of more than 3 seconds objectified in the long-term ECG are an indication, even for asymptomatic patients.

Most often, dual-chamber rate adaptive systems are implanted because they provide the best results.

9 pacemaker controls

A pacemaker should be checked in the first 3 months after implantation. Among other things, the chronic stimulus threshold can be determined and necessary changes to the programming can be made. If the situation is stable, a six-monthly to annual check should be carried out in the following period.

The service life of a pacemaker is linked to the capacity of the built-in battery. It is reduced if the probe position is inadequate (higher currents required) and frequently required stimulation. As a rule, it is necessary to change the unit after 8-10 years.

The pacemaker controls are not invasive. The devices are read and programmed transcutaneously. Every patient with a pacemaker should receive a pacemaker card in which the device type, the indication for therapy and the check-up appointments are entered.