TELEMETRY SYSTEM FOR AN IMPLANTABLE CARDIAC DEVICE

摘要

A telemetry system and method of monitoring cardiac activity or providing therapy to the heart for an implantable cardiac device reduces power consumption of the cardiac device and assures accurate transmission of data. The system includes a receiver and a transmitter in an external programmer and a receiver section and transmitter section in the cardiac device. The cardiac device is implanted beneath the skin of a patient and includes circuit means which monitors activity of the heart of the patient and generates data indicative of the monitored activity. The receiver section and the transmitter section of the cardiac device are coupled to the circuit means for communicating with the external programmer. The receiver section and the transmitter section of the cardiac device generally remain in a de-energized state. The receiver section is energized at spaced apart time intervals to detect an initiation signal transmitted by the external programmer. If the initiation signal is detected, the receiver section and the transmitter section of the cardiac device are fully activated. Command transmissions from the external programmer and data transmissions from the cardiac device include means for verifying the accuracy of transmission. Portions of transmissions may be retransmitted to correct transmission errors. The external programmer includes a signal strength indicating means for providing an indication of received signal strength which the user can use to position the receiver and transmitter in the external programmer for optimum received signal strength. The antenna or antennas are disposed in the header of the implanted device to facilitate communication at high speed.