| 摘要 |
<p>A defibrillator has a signal generator implemented to deliver output shock waveforms and housed in a case adapted to be implanted in the left pectoral region of a cardiac patient. The case is implemented to interact with internal circuitry of the generator to maintain the case active as an electrode. An electrical transvenous lead has a proximal electrode for electrical connection to the internal circuitry of the signal generator and a distal end adapted to be positioned in the right ventricle (RV) of the patient's heart. The lead includes a sensing tip for contacting the RV to sense the patient's ECG signal and a shocking coil arranged to be located in the RV when the transvenous lead is implanted in the patient. The internal circuitry of the signal generator includes triggerable output circuit for developing an output shock waveform when triggered in response to detection of ventricular fibrillation of the patient's heart from the sensed ECG signal. The internal circuitry also includes a timer responsive to the sensed ECG signal for timing the application of the shock waveform developed by the output circuit across the transvenous lead and the active case with a predetermined delay relative to the occurrence of an R-wave of the sensed ECG signal next following detection of fibrillation until at least about 50 % of the R-R cycle length of the ECG signal has elapsed, to optimize the timing of delivery of an electric field vector derived from the shock waveform across a myocardial mass of the patient's heart between the shocking coil and the active case.</p> |
