title: Genesis of arrhythmias and mechanism of electrical defibrillation of the heart.
abstract: Atrial arrhythmias were induced in experiments on dogs by electrical stimulation or by local application of aconitine and methacholine to the atrium. The action of the defibrillator discharge on these arrhythmias was studied. The defibrillator discharge abolished the arrhythmias maintained by the circus movement of the excitation wave over the atria but did not abolish sinus tachycardia or ectopic aconitine tachysystoles. The threshold of the defibrillating effect depends on the existence of micro-or macro-reentries. Thmechanism of defibrillation consists of excitation of the atrial myocardium with a consequent decrease in the pathway for the circulation of excitation to below the critical size for maintaining the circus movement of the excitation wave. The axtion of the defibrillator does not inihibit the automatism of the nomotopic and heterotopic cardiac pacemakers.
mesh_terms: D031841:Aconitum; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology* / Q000628:therapy; D004285:Dogs; D004554:Electric Countershock; D004558:Electric Stimulation; D006325:Heart Atria / Q000503:physiopathology; D008688:Methacholine Compounds
chemical_list: D008688:Methacholine Compounds