The cardiology exams

THE IMPLANTATION OF A PACEMAKER
(and of an AUTOMATIC IMPLANTABLE DEFIBRILLATOR)

- A few explanations
- Mode and principle of the cardiac stimulation
- Implantation of the cardiac pacemaker
- Possible complications
- Your cardiac pacemaker carrier's follow-up
- What can cause your cardiac pacemaker to malfunction

MODE AND PRINCIPLE OF THE CARDIAC STIMULATION

1 - Cardiac stimulation mode:

It essentially depends on the area of the damaged nervous tissue. If this tissue is injured at the level of the atrium, then an isolated stimulation of the atrium is sufficient. If the nervous tissue is damaged at the level of the ventricles, an electric stimulation of this cavity is necessary,whereas it is unnecessary to stimulate the atrium. These cardiac pacemakers are called mono- chambers.

But in fact, some aspects must be taken into account:

The physicians know well that the nervous tissues wear out with age, in particular the area situated between the atrium and the ventricle (the atrioventricular node). Thus, an isolated stimulation of the atrium risks not inducing any stimulation of the ventricle if this area does not normally transmit the nervous impulse.

On the other hand, physicians prefer to respect a synchronization between the atrium and the ventricle, so that the heart contracts as efficiently as possible.

For those reasons, the physician has the possibility to put a stimulation into the atrium and the ventricle in place, which is synchronized between these two cavities. These cardiac pacemakers are called dual chamber pacemakers.

2 – Principles:

The cardiac stimulation includes:

1 - A case, containing a battery with a limited life span, whose role is to provide the electric impulses while taking into account the heart natural activity.

This case is thus capable of listening to the heart natural activity, and of stimulating the adapted cavity;

Displaying a cardiac pacemaker case.

2 - One or several stimulation probes, which will be placed into the adapted cardiac cavities.

Displaying a cardiac stimulation probe.

3 - Coding the pacemaker:

An international code has been established according to the different cardiac stimulation modes, permitting to understand the pacemaker’s working mode very quickly.

The first letter defines the site of stimulation: A for the atrium, V for the ventricle, and D for the two cavities;

The second letter, according to the same code as previously, defines the site of detection.

The working mode is defined by the third letter: I for inhibiting, T for triggering and D for both.

A cardiac pacemaker inducing an electric impulse in the ventricle detects the ventricle natural activity and inhibits if a spontaneous activity of the ventricle occurs, is thus called VVI.

A pacemaker stimulating the two cavities (atrium and ventricle), “listens” to the two cavities, and corresponds to both working modes, is called DDD.

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File last modified on june 9, 2006