Periodic electrical lead intergrity testing system and method for implantable cardiac stimulating devices

DETAILED DESCRIPTION This invention provides a system for periodically testing the integrity of electrical leads used with implantable cardiac stimulating devices that deliver therapeutic shocks (such as cardioversion or defibrillation shocks) to cardiac tissue.
This invention is particularly advantageous in the context of implantable cardiac stimulating devices that provide multiple forms of therapy.
The electrical lead integrity testing system of the present invention detects electrical problems more effectively than known lead integrity testing systems which simply store data collected during the last therapeutic shock delivered for the physician to evaluate at the patient's next follow-up visit.
The electrical lead integrity testing system of the present invention advantageously minimizes the amount of energy consumed for testing purposes.
This is accomplished by applying low energy test pulses to the lead system, which have a significantly lower energy content than therapeutic shocks.
The lead integrity testing system generates data characterizing the impedance of the lead system as either acceptable or too high, even if a therapeutic shock has not been delivered since the last follow-up visit.
In this way, electrical lead fractures can be detected and the patient can be warned prior to delivery of a therapeutic shock.
Moreover, the present invention prevents damage to control and logic circuitry by electrically isolating high voltage operations from low voltage operations.
While maintaining electrical isolation between the high and low voltage circuits of the device, the present invention allows data obtained by the lead integrity testing circuitry located within the high voltage circuitry of the device to be communicated to the low voltage control and logic circuitry for analysis and processing.
This communication is accomplished without the need to add costly and bulky hardware to existing devices.
In addition, the present invention provides for periodic testing of lead integrity at intervals that can be programmed by the physician