Vulnerability to Fibrillation and the Ventricular-Excitability Curve1
نویسندگان
چکیده
P REVIOUS reports have given a description of the cyclic changes in excitability of both auricle and ventricle of the dog’s heart (I, 2). It was found that the dog’s auricle is ‘vulnerable’ to fibrillation throughout the major dip area of the excitability-recovery curve (3). A study of ventricular vulnerability has now been made. Cats and turtles were used almost exclusively in this investigation because their smaller hearts could be defibrillated more easily than the ventricle of the dog. The secondary purpose of this study was to determine whether or not the phenomena of the recovery of excitability are similar in the hearts of different vertebrates.
منابع مشابه
Vulnerability of the dog ventricle and effects of defibrillation.
Vulnerability to ventricular fibrillation has been studied in 20 dogs by means of test stimuli of known strength and duration in order to ascertain the relationship between the vulnerable period and the recovery of excitability and to determine the effects of countershock defibrillation. The relative refractory period is found to be the only portion of the cycle during which fibrillation could ...
متن کاملVulnerability to fibrillation and the ventricular-excitability curve.
P REVIOUS reports have given a description of the cyclic changes in excitability of both auricle and ventricle of the dog’s heart (I, 2). It was found that the dog’s auricle is ‘vulnerable’ to fibrillation throughout the major dip area of the excitability-recovery curve (3). A study of ventricular vulnerability has now been made. Cats and turtles were used almost exclusively in this investigati...
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Lethal ventricular arrhythmias have occurred in patients taking thioridazine. Therefore, we studied two canine models to determine if thioridazine alters vulnerability to ventricular fibrillation. In 30 chloralose-anesthetized dogs, the repetitive response threshold was used to assess vulnerability during right ventricular stimulation with transvenous catheter electrodes. Placebo, 10 mg/kg of t...
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BACKGROUND In Langendorff-perfused hearts and in hearts on cardiopulmonary bypass, chemical ablation of the subendocardium of both ventricles decreases ventricular vulnerability to fibrillation. It was hypothesized that the effects of ablation are a result of the elimination of the subendocardial Purkinje fiber network. This hypothesis has been supported by recent observations that the supernor...
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• Asynchrony of recovery from the refractory state has been emphasized repeatedly as a major factor in the induction of ventricular fibrillation by strong stimuli applied during the "vulnerable" period. The role of asymmetry of refractoriness, excitability, and conduction has been appraised thoroughly by Brooks et al. Some of the postulates proposed in their discussion have been tested and supp...
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