IMPLANTABLE MEDICAL DEVICE AND POWER SOURCE DEPLETION CONTROL THEREFOR
 Inventor: Lodewijk-Jozef Herpers,
 Assignee: Medtronic, Inc., Minneapolis, Minn.
 Appl. No.: 235,069
 Filed: Feb. 17, 1983
 Int. CV D61N1/36
 U.S. CI 128/419 PG; 128/419 PT
 Field of Search 128/419 PG, 419 PS,
 References Cited
U.S. PATENT DOCUMENTS
3,738,371 6/1973 Raddi 128/419
3,789,854 2/1974 Lee 128/419
3,901,247 8/1975 Walmsley 128/419
4,091,817 5/1978 Thaler 128/419
4,102,345 7/1978 Cannon 128/419
4,120,307 10/1978 Jirak 128/419 PT
4,190,055 2/1980 Walters et al 128/419 PT
4,248,238 2/1981 Joseph 128/419 PG
FOREIGN PATENT DOCUMENTS
2014858 9/1979 United Kingdom .
Primary Examiner—-William E. Kamm
Attorney, Agent, or Firm—Joseph F. Breimayer; John L.
Rooney; Robert C. Beck
A programmable pulse generator capable of operating in several atrial and ventricular pacing modes having atrial and ventricular sense amplifiers and output circuits, programmable memory and clock controlled digital timing circuits and a depletable power source. Endof-life sensing circuits detect first and second end-of-life depletion levels. Magnet activated end-of-life test circuitry responds to the presense of none, one or both of the end-of-life depletion level signals to alter the operating modes and pacing rates to indicate the orginally programmed mode and the level of depletion to an observer. Preferably, the pulse generator is operated in the asynchronous DOO or VOO modes and at non-programmed test rates to provide the indication.
30 Claims, 7 Drawing Figures