CARDIAC PACER WITH EXTERNALLY CONTROLLABLE VARIABLE WIDTH OUTPUT PULSE

• US 3,713,449 A
• Filed: 08/31/1970
• Issued: 01/30/1973
• Est. Priority Date: 08/31/1970
• Status: Expired due to Term

• Current Assignee: Med-El Incorporated
• Original Assignee: Pieter M.J. Mulier
• Inventors: Mulier, Pieter M. J.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/068,347
• Time in Patent Office: 883 Days
• Field of Search: 128/419P,419R,421,422 331/111
• US Class Current: 607/11
• CPC Class Codes: A61N 1/362 Heart stimulators heart defibrillators A61N1/39

Abstract

An implantable cardiac pacer having electrode means adapted to be connected to the hart and electrical circuitry connected to the electrodes for providing hart stimulation pulses. The electrical circuitry includes a pulse generator for providing a timed pulse and means for selectively varying the pulse width. The electrical circuitry also includes means for providing a substantially constant voltage or current output pulse, regardless of change in load impedance. The circuitry is encapsulated in a substance substantially inert to body fluids and tissue, and the means for varying the pulse width is preferably controlled by a nonmechanical contact with a device external to the encapsulating substance.

Claims

1. In an implantable cardiac pacer, including electrical circuit means for providing stimulation pulses to electrode means adapted to be connected to a heart, the circuitry encapsulated in means substantially inert to body fluids and tissue, the improvement comprising:

remotely controllable first means connected to the electrical circuit means for selectively varying the width of the stimulation pulses from values sufficient to achieve cardiac capture to values at which cardiac capture is lost;

the electrical circuit means including second means for providing the stimulation pulses at a generally constant level;

said first and second means encapsulated in the means substantially inert to body fluids and tissue; and

further means external to the means substantially inert to body fluids and tissue for varying the remotely controllable first means.

2. The apparatus of claim 1 in which the further means and the first means include means for producing magnetic coupling therebetween.

3. The apparatus of claim 1 in which the second means is for providing the stimulation pulses at a generally constant current.

4. The apparatus of claim 1 in which the second means is for providing stimulation pulses at a generally constant voltage.

5. An improved implantable medical-electrical apparatus comprising:

electrical circuit means for providing timed stimulation pulses to electrode means adapted to be connected to a portion of a body in which the apparatus is implanted;

the electrical circuit means including pulse generator means having timing circuit means for controlling stimulation pulse width and rate;

the timing circuit means including a portion having remotely controllable selectively variable electrical characteristics for selectively varying the stimulation pulse width from values sufficient to achieve cardiac capture to values at which cardiac capture is lost;

means adapted to be placed external to the body for selectively varying the electrical characteristics of the portion of the timing circuit means; and

the electrical circuit means including further circuit means for maintaining the stimulation pulses at a substantially constant voltage level.

6. The apparatus of claim 5 in which the further circuit means is for maintaining the stimulation pulses at a substantially constant current level.

7. The apparatus of claim 5 in which the timing circuit means comprises R-C time constant means.

8. The apparatus of claim 7 in which the portion of the timing circuit means comprises variable resistance means.

9. The apparatus of claim 8 in which the variable resistance means and the means external to the body include means for producing magnetic coupling therebetween.