| 摘要 |
One embodiment of the present invention is a mode switching method and apparatus for an external, dual chamber cardiac pacemaker having multiple single chamber and dual chamber primary pacing modes and user adjustable atrial and ventricular sensitivities. The dual chamber demand pacing mode, e.ga. the DDD or DDI mode, is in effect as long as the atrial and ventricular pace pulse amplitudes are set by the user within an operative range. The pacing mode is switched to a single chamber demand mode when one of the atrial and ventricular pace pulse energies is set to an inoperative setting which preferably is a no output setting. If the atrial pace pulse amplitude is set to no output, then the mode is switched to a single chamber demand mode with ventricular sensing and pacing, preferably the VVI mode. If the ventricular pace pulse amplitude is set to no output, then the mode is switched to a single chamber mode with atrial sensing and pacing, preferably the AAI mode. In the implementation of the invention, the setting of atrial or ventricular pace pulse amplitude to the OFF position is detected, and the corresponding atrial or ventricular sense amplifier is effectively rendered inoperative, resulting in the mode switch. The mode switch back to the dual chamber demand pacing mode is effected by setting the atrial or ventricular pace pulse amplitude to any level other than the no output position. Preferably, the mode switch is back to the DDD mode, even if the preceding mode switch was from the DDI mode.
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