[Anti-bradycardia pacemaker therapy: rational choice of system in relation to hemodynamic and prognostic aspects]

Currently, the most important indications for pacemaker treatment include high-grade AV-block, the sinus node syndrome, atrial fibrillation with slow ventricular rate as well as the hypersensitive carotid sinus. In the Federal Republic of Germany, 88.5% of the units employed were fixed-rate ventricular single-chamber systems (VVI), in less than 10% dual-chamber systems (DDD) and in 2.4% fixed-rate atrial single-chamber systems (AAI) as well as rate-adaptive systems (VVIR, AAIR). In 1986, a total of 32,000 pacemakers were implanted in the Federal Republic and about 105,000 in the USA. State-of-the-art: Miniaturization of single-chamber systems to less than 20 grams and dual-chamber systems to less than 30 grams has been associated with markedly improved lead technology which has lowered energy requirements. The development of atrial-independent, variable rate systems has enabled rate adaptation in patients who are not candidates for DDD-stimulation or in whom the atrial rate is inadequate. With Holter functions various physiological parameters can be continuously monitored and their response as well as biorhythmicity are analyzed.

The following guidelines are those of the working group "Cardiac Pacing" of the German Society for Heart and Circulatory Research for the choice of pacemaker systems which are considered to provide the best respective physiologic form of stimulation with the goal of rendering optimal hemodynamics. For characterization of the pacemaker modes, the five-letter NASPE/BPEG code is used. The possibility for single modes, AV-synchrony and rate adaptation as central factors for physiologic stimulation forms is shown in Table 2. Those systems are designated as "physiologic" which reestablish AV-synchrony, that is, pacing modes in which the atria are incorporated With the VAT-, VDD- and DDD-modes there is an additional atrial-triggered rate modulation. In AAI- order DDD/I-modes rate adaptation is independent of the atria (AAIR, DDD/IR) via physiologic parameters while rate-adaptive VVI stimulation does not enable AV-synchrony. Atrioventricular conduction disturbances: Pacemaker treatment is carried out for prevention of Adams-Stokes symptoms and for improvement of the hemodynamic situation. Prognostic implications of pacemaker treatment: With pacemaker treatment the one-year mortality of patients with Adams-Stokes symptoms and/or complete AV-block can be lowered to 5 to 19% from 50 to 70%.(ABSTRACT TRUNCATED AT 400 WORDS)