| 摘要 |
A cardiac stimulator apparatus for effecting cardioversion or defibrillation in the event of pathologic tachycardia or ventricular fibrillation in which the rate of heart depolarization signals is compared to a predetermined heart rate value indicative of the onset of tachycardia while, simultaneously, the heart's pre-ejection period is monitored to sense whether an increase in heart rate above the predetermined value is accompanied by a decrease in the pre-ejection period. If not, a pathologic rather than a physiologic episode is diagnosed and a cardioversion pulse protocol is initiated. By also monitoring the mechanical pulse of the heart, if an inordinately high heart rate is accompanied by a low or non-existing mechanical pulse, ventricular fibrillation is diagnosed and the cardioverter is triggered to shock the heart back into sinus rhythm. If the mechanical pulse rate tracks the electrical rate of depolarization, tachyarrythmia is confirmed. The diagnosis may be further confirmed by taking into account the rate at which the heart rate increases. |
