[Anti-tachycardia stimulation in supraventricular and ventricular tachycardia with and without cardioverter/defibrillator].
Reentry is the underlying electrophysiologic mechanism in most of the clinically occurring tachycardias. It has been known for 25 years that a reentrant circuit can be interrupted by correctly timed stimuli during programmed stimulation. Although there has been a continuous technological progress in pacemaker technology in the last ten years, application of pacemaker therapy for the treatment of atrial as well as of ventricular tachyarrhythmias did not increase significantly. Prophylactic permanent pacing preventing the onset of tachyarrhythmias has not become an accepted therapeutic approach and is still a matter of research. Antitachycardia pacing designed to interrupt a reentrant circuit uses single or multiple extrastimuli which invade the excitable gap of the reentrant circuit so that antegrade and retrograde conduction within the circuit becomes impossible. The excitable gap, however, is not a fixed electrophysiological parameter, but its width depends mainly on the influence of the sympathetic and parasympathetic nervous system. Therefore, a variety of stimulation programs delivered by the implanted pacemaker had to be invented in order to adapt to the constantly changing electrophysiologic parameters. It becomes obvious that application of burst stimulation is more effective than delivery of single or double extra stimuli and that tachycardia rate-related pacing is more reliable than fixed-rate pacing for tachycardia interruption. The most effective termination mode seems to be self-adaptive auto-decremental pacing with constantly decreasing intervals between multiple stimuli and addition of further impulses for each new termination attempt. The risk of acceleration of tachycardia or induction of non-clinical tachyarrhythmias is higher with burst-stimulation than with single or double extra stimuli. Fast tachycardia rates are more prone to acceleration than slower ones. Tachycardia detection algorithms are based mainly on rate, sudden onset and rate stability of the tachycardia. In order to reliably distinguish pathologic tachycardias from sinus or physiologic tachycardias, other than rate-detection parameters will be applied in the future. These are endocardial electrogram signal-analysis, frequency content of the endocardial signals as well as biological sensors. A prerequisite for successful permanent antitachycardia pacing is a thoroughly performed preoperative electrophysiologic study in order to identify the most reliable and effective tachycardia termination mode. This requires multiple induction of the clinical tachycardia under various conditions, different activity or posture states as well as under the influence of antiarrhythmic drugs.(ABSTRACT TRUNCATED AT 400 WORDS)
Klein
H
H
Abteilung Kardiologie, Medizinischen Hochschule Hannover.
D004554:Electric Countershock / Q000295:instrumentation*; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008838:Microcomputers; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012984:Software; D013610:Tachycardia / Q000503:physiopathology / Q000628:therapy*; D013617:Tachycardia, Supraventricular / Q000503:physiopathology / Q000628:therapy*
Antitachykarde Stimulation bei supraventrikulären und ventrikulären Tachykardien mit und ohne Kardioverter/Defibrillator.