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The indications for the implantation of a permanent pacemaker should be clear cut. A poor indication, or the choice of an inappropriate system may have disastrous consequences (see p. 187, pacemaker syndrome), and discredit the treatment. When considered for a patient suffering from an incurable illness, each case must be evaluated individually, including the patient, family and referring physician in the decision making process.

The various pacing modes have been classified according to an international code which allows the immediate understanding of the overall function of a pacemaker. A three letter code was originally used. Technological advances have mandated the addition of a fourth and fifth letter.

The formation and propagation of the electrical signal which signals the contraction of the heart muscle, stems from the activity of nodal tissue, made of distinct myocardial cells, organized within specialized anatomical structures (Figs. 1.1, 1.2).

This chapter repeats elements already presented in previous sections, this time in the perspective of the usual practical and clinical considerations that apply to the long-term surveillance of pacemaker patients.

The myocardial cellular membrane may be viewed as an electrical capacitor. When an electrical stimulus is applied to it, an action potential is triggered. Given a sufficient current strength, above the depolarization threshold, activation will propagate by contiguity to the entire myocardium and provide the signal for myocardial contraction. Thus, cardiac stimulation requires the formation of a localized and transient electrical field to depolarize a few cells in the vicinity of the electrode. This role is assumed by the pacing system which consists of a battery, interfaced with an electronic circuitry which delivers electrical current to the myocardium via a lead whose extremity includes an electrode in contact with endocardium or epicardium.

The examination of the main functions of a pacemaker will be presented with the assistance of examples, and a practical and clinical goal in mind. The complex functions already presented in Chap. 3 and its appendix will not be reviewed here. The gathering of information necessary for a reliable device examination and optimal programming implies a thorough knowledge of the implanted model and its programmer (Figs. 8.1, 8.2). Before proceeding with testing, it is most important to print the current values of the various parameters in order to easily retrieve them in case one wishes to restore them at the end of the test, as well as the power consumption of the device with respect to the programmed parameters. Consequently, all data retrieved from telemetry must be printed since they may be erased during the reprogramming needed to test the sensing and pacing functions.