Implantable cardiac stimulation device having reduced shelf current consumption and method

A processor controlled implantable cardiac stimulation device having a processor, a real-time clock circuit, a watch dog timer circuit having a duty cycle, a telemetry circuit capable of operation in either an active mode or a standby mode, and ancillary circuits that sense cardiac activity and provide stimulation pulses to a heart, the device comprising:

• a power source for providing power to all of the circuits of the device;
• and
• a shelf mode circuit that disables power to the ancillary circuits, decreases the duty cycle of the watch dog timer, sets the processor into a static state, and sets the telemetry circuit to the standby mode in response to shelf mode commands received by the telemetry circuit to set the device from an active powered mode to a shelf mode and reduce shelf current consumed by the device;
• wherein the device is an implantable defibrillator having a plurality of capacitors requiring periodic reforming and wherein the device includes a reform circuit that periodically charges the capacitors;
• and
• wherein the reform circuit causes the shelf mode circuit to return the device to the active powered mode prior to reforming the capacitors and causes the shelf mode circuit to reassert the shelf mode after charging the capacitors.

An implantable cardiac stimulation device including processing means for controlling operation of the device, real-time clock means for providing clock signals to the processing means, watch dog timer means operable at a duty cycle rate for detecting malfunction of the processing means, telemetry means for receiving external commands when in an active state and wake-up commands when in a standby state, therapy means for sensing cardiac activity and providing stimulation pulses to a heart, and depletable power supply means for supplying power to the processing means, the real-time clock means, the watch dog timer means, the telemetry means and the therapy means, an arrangement for placing the device into a shelf mode from a fully activated powered mode and reducing shelf current consumed by the device, the arrangement comprising shelf mode establishing means for disabling supply of power to the therapy means, decreasing the duty cycle of the watch dog timer means, setting the processor into a static state, and setting the telemetry means to the standby state responsive to shelf mode commands received by the telemetry means for placing the device into the shelf mode;

• wherein the watch dog timer means remains operational at the reduced duty cycle to detect processor errors during the shelf mode;
• and
• wherein a transmitting circuit of the telemetry means is disabled during the standby state and a receiving circuit of the telemetry circuit remains active during the standby state.

An implantable cardiac stimulation device including processing means for controlling operation of the device, real-time clock means for providing clock signals to the processing means, watch dog timer means operable at a duty cycle rate for detecting malfunction of the processing means, telemetry means for receiving external commands when in an active state and wake-up commands when in a standby state, therapy means for sensing cardiac activity and providing stimulation pulses to a heart, and depletable power supply means for supplying power to the processing means, the real-time clock means, the watch dog timer means, the telemetry means and the therapy means, an arrangement for placing the device into a shelf mode from a fully activated powered mode and reducing shelf current consumed by the device, the arrangement comprising shelf mode establishing means for disabling supply of power to the therapy means, decreasing the duty cycle of the watch dog timer means, setting the processor into a static state, and setting the telemetry means to the standby state responsive to shelf mode commands received by the telemetry means for placing the device into the shelf mode;

• wherein the device is an implantable defibrillator having a plurality of capacitors requiring periodic reforming and wherein the arrangement includes reform means for periodically charging the capacitors;
• and
• wherein the reform means causes the shelf mode establishing means to return the device to the fully active powered mode prior to reforming the capacitors and causes the shelf mode establishing means to reassert the shelf mode after charging the capacitors.

In a processor controlled implantable cardiac stimulation device having a real-time clock circuit, a watch dog timer circuit having a duty cycle, a telemetry circuit capable of operation in either an active mode or a standby mode, ancillary circuits that sense cardiac activity and provide stimulation pulses to a heart, and a power source that provides power to all of the circuits, a method of setting the device from an active powered mode to a shelf mode for reducing shelf current consumed by the device, the method including the steps of:

• receiving a shelf mode command signal with the telemetry circuit;
• and
• responsive to receiving the shelf mode command signal, placing the device into the shelf mode by disabling power to the ancillary circuits, decreasing the duty cycle of the watch dog timer, setting the processor into a static state and setting the telemetry circuit in the standby mode;
• wherein the watch dog timer remains operational at the decreased duty cycle to detect processor errors during the shelf mode;
• and
• wherein a transmitting circuit of the telemetry circuit is disabled during the standby mode and a receiving circuit of the telemetry circuit remains active during the standby mode.

In a processor controlled implantable cardiac stimulation device having a real-time clock circuit, a watch dog timer circuit having a duly cycle, a telemetry circuit capable of operation in either an active mode or a standby mode, ancillary circuits that sense cardiac activity and provide stimulation pulses to a heart, and a power source that provides power to all of the circuits, a method of setting the device from an active powered mode to a shelf mode for reducing shelf current consumed by the device, the method including the steps of:

• receiving a shelf mode command signal with the telemetry circuit;
• and
• responsive to receiving the shelf mode command signal, placing the device into the shelf mode by disabling power to the ancillary circuits, decreasing the duty cycle of the watch dog timer, setting the processor into static state and setting the telemetry circuit in the standby mode;
• wherein the device is an implantable defibrillator having a plurality of capacitors requiring periodic reforming and wherein the method further includes the step of charging the capacitors at periodic intervals;
• and
• wherein the reforming step includes the steps of returning the device to the active powered mode prior to reforming the capacitors and replacing the device in the shelf mode after charging the capacitors.