| 摘要 |
A medical interventional device is adapted to be implanted in a patient's body to provide a number of different controllable therapeutic functions including cardiac pacing, antitachycardia pacing, cardioversion and defibrillation. A sensor generates an electrical signal representing sensed variations of a physiologic parameter of the patient indicative of the substantially instantaneous hemodynamic condition of the patient. The physiologic parameter sensed may be any of blood pressure, blood oxygen content, minute ventilation, central venous temperature, pulse rate, blood flow, physical activity, or other parameter for that purpose. A computer calculates the mean and standard deviation of the generated signal over a predetermined time interval, and especially the quotient of the standard deviation and the mean from which to determine a sudden hemodynamic change such as a precipitous drop in cardiac output. The device accepts this as an indication of syncope warranting intervention with a defibrillating protocol, and triggers such response.
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