Implantable cardioverter defibrillator with automatic switching to a pre-set pacing mode following delivery of a shock

An implantable cardiac stimulator comprising:

• a pacing pulse generator configured to deliver pacing pulses to at least one chamber of a heart;
• a high energy pulse generator configured to deliver at least one shock selected from the group consisting of cardioversion shocks and defibrillation shocks to at least one chamber of the heart;
• sensing circuitry configured to interact with the heart to sense intrinsic cardiac activity and cardiac activity resulting from capture following a delivered pacing pulse;
• and
• a control unit connected to said pacing pulse generator, said high energy pulse generator and said sensing circuitry that normally operates said pacing pulse generator in a first mode, including executing an autocapture mode, and that automatically switches said pacing pulse generator from operating in said first mode to operate in a second mode following delivery of a shock by said high energy pulse generator for a post-shock duration and, in said second mode, said control unit operating said pacing pulse to deliver pacing pulses with fixed settings for said pacing pulses and the control circuit does not operate the pacing pulse generator in the autocapture mode during the post-shock duration;
• and
• said sensing circuitry also being configured to measure signal characteristics of said intrinsic cardiac activity signal following said shock, and wherein said control unit is configured to switch said pacing pulse generator back to said first mode after said post-shock duration, wherein the post-shock duration is extendable by said control unit, dependent on said characteristics of the sensed intrinsic cardiac activity following said shock, until the control unit determines that resumption of said autocapture mode in said first mode will be unaffected by said delivery of said shock.