Implantable medical device power source depletion indicators

Claim 1

A programmable medical device including a) an atrial pulse providing means (161) for providing atrial stimulating pulses, said pulse providing means including an atrial capacitor (134), b) means for detecting ventricular depolarizations (12), c) means for applying external programming signals to the programmable device for programming variable operational parameters and variable modes (32, 124, 126), d) programmable digital control means (18) including, i) means for storing (Fig.2 - 212, 214) variable digital information derived from said externally applied programming signals relating to a variable desired interval between a detected ventricular depolarization and the production of an atrial stimulation pulse, ii) means for providing (Fig.2 - 216, 218, 222, 224, APT, P-pace) a triggering signal (PWA) for discharging the atrial capacitor at the end of said variable desired interval derived from said external programming signals, iii) means for providing and applying a control signal (SV1, SV2, Fig.2b - 218, 220, 222, 86, 88) to the means for detecting ventricular depolarizations (12) to disable this detecting means for a predetermined period of time, at the time when said atrial capacitor (134) is discharged by said triggering signal (PWA) so that the means for detecting ventricular depolarizations (12) cannot sense said atrial stimulation pulse and mistake it for a ventricular depolarization, and, iv) means for providing and applying a fast recharge control signal (FRV, Fig.2b - 156, 224) to initiate recharge of the atrial capacitor (134).