[Mechanism of induction and termination of ventricular fibrillation--significance of dispersion of ventricular repolarization].
It has been known for many years that ventricular fibrillation may be induced and terminated by electrical field stimuli. Recent experimental studies have shown that both fibrillation and defibrillation have a common electrophysiologic mechanism that is based on the interaction between the electrical field stimulus and ventricular repolarization. Ventricular fibrillation will be induced if the field stimulus is applied with the area of vulnerability, this area of vulnerability is defined two dimensionally by the shock coupling interval and shock strength, and is modified by the configuration of the shock. A field shock that is applied within the area of vulnerability causes heterogeneity of ventricular repolarization immediately after the shock (postshock dispersion), thereby enabling the development of circuit movements and reentry, and resulting in ventricular fibrillation. High energy shocks, however, that are applied above the area of vulnerability (i.e., above the upper limit of vulnerability) will not induce ventricular fibrillation due to homogeneous prolongation of repolarization and a resulting small postshock dispersion. In analogy, ventricular fibrillation will continue after unsuccessful low-energy defibrillation shocks due to high postshock dispersion, whereas a high-energy shock will synchronize ventricular repolarization, thereby causing small postshock dispersion and termination of ventricular fibrillation. This paper describes the relation between fibrillation, defibrillation and ventricular repolarization based on experimental findings. A possible clinical application of these findings is that the upper limit of vulnerability may be used as a surrogate for the defibrillation threshold. Thus, defibrillation threshold testing may not be necessary during future implantations of automatic cardioverter defibrillators.
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Medizinische Klinik II Kardiologie & Pulmologie Universitätsklinikum Benjamin Franklin der Freien Universität Berlin Hindenburgdamm 30 D-12200 Berlin.
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D017147:Defibrillators, Implantable; D004554:Electric Countershock; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D011379:Prognosis; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000628:therapy
Mechanismus der Induktion und Terminierung von Kammerflimmern--Bedeutung der Dispersion der ventrikulären Repolarisation.