| Autor: |
Geddes, L., Niebauer, M., Babbs, C., Bourland, J., Geddes, L A, Niebauer, M J, Babbs, C F, Bourland, J D |
| Zdroj: |
Medical & Biological Engineering & Computing; 1985, Vol. 23 Issue 2, p122-130, 9p |
| Abstrakt: |
The efficacy (threshold average current density) and safety factor (overdose current density for a 50 per cent decrease in myocardial contractility) were determined for the rectangular, trapezoidal and damped sine wave defibrillating current waveforms using a new blood-perfused, isolated, working canine heart in an isoresistive and isotonic volume conductor. This preparation permits the achievement of defibrillation with the heart in as uniform a current density field as possible and eliminates myocardial deterioration due to the traditional loss of coronary perfusion during ventricular fibrillation. Since the heart is isolated, it is not subject to any neural influences. It was found that, for a given pulse duration, the threshold average current density (efficacy) values were very similar among the three current waveforms. It was also found that the safety factors for the three current waveforms ranged from 3·2 to 5·3, the conventional 4-6 ms damped sine wave having a safety factor of 5·0±0·9 (1SD). [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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