DEVICE FOR STARTING OR STIMULATING HEART CONTRACTIONS

• US 3,669,120 A
• Filed: 07/09/1970
• Issued: 06/13/1972
• Est. Priority Date: 07/11/1969
• Status: Expired due to Term

• Current Assignee: Lars Stig Nielsen
• Original Assignee: Lars Stig Nielsen
• Inventors: Nielsen, Lars Stig
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/053,557
• Time in Patent Office: 705 Days
• Field of Search: 128/419P,419R,421,422
• US Class Current: 607/27
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371

Abstract

A Pacemaker of the demand type having an output control circuit arranged to control the produced pace impulses in such a manner that the amplitude of each impulse is slightly less than that of the preceding impulse. When the amplitude has decreased below the threshold value so that a heart impulse fails to occur within a predetermined period, a reset circuit will cause another pace impulse to be produced having a given initial amplitude.

Claims

1. A Pacemaker comprising a pair of electrodes adapted to be inserted in or near the heart of a patient, a pulse generator for producing heart stimulating pacing pulses of substantially fixed frequency, which pulses are applied to said electrodes, and a detector connected to the electrodes and to the pulse generator and adapted to detect the heart pulses that trigger muscular contractions of the heart and to control the pulse generator to produce a pacing pulse on the absence of a heart pulse for a predetermined period, characterized in that means are provided in operative relationship for gradual reduction of the amplitude of selected pacing pulses and means are operatively connected for producing predetermined initial amplitude, after the absence of a heart pulse for a certain period after the provision of a reduced pacing pulse.

2. A Pacemaker according to claim 1, characterized in that the amplitude reducing means reduces the amplitude of each pacing pulse by a fixed or relative value with respect to the preceding pacing pulse.

3. A Pacemaker according to claim 1, further comprising an output circuit connected to said electrodes and containing a condenser, an electronic switch connected in series with said condenser, and a charging circuit operatively connected for charging the condenser to a controllable potential.

4. A Pacemaker according to claim 3, characterized in that the amplitude reducing means include a dosage circuit containing a dosage condenser operatively connected so that the voltage of the dosage condenser controls the potential to which the output condenser is charged, and a charging circuit and a discharging circuit connected in circuit relationship with the dosage condenser.

5. A Pacemaker according to claim 4 and in which the pulse generator comprises a resetable astable multivibrator, characterized in that it comprises a first monostable multivibrator which is activated by said astable multivibrator after each completed cycle thereof to produce a trigger pulse, a second monostable multivibrator in operative circuit relationship with said first monostable multivibrator to be activated by the leading edge of said trigger pulse and to control the electronic switch of the output circuit, and wherein said amplitude producing means include a restoration circuit in operative circuit relationship with said first monostable multivibrator to be activated by the trailing edge of said trigger pulse in the absence of a detected heart pulse to adjust the dosage circuit to full pace pulse amplitude.

6. A Pacemaker according to claim 5, characterized in that the charging circuit of the dosage circuit comprises an electronic switch connected in series with the dosage condenser and further connected to said second monostable multivibrator so as to be controlled by the trigger pulses.

7. A Pacemaker according to claim 5, characterized in that the discharging circuit of the dosage circuit is connected in parallel with the dosage condenser and includes an electronic switch operatively connected to the restoration circuit as to be controlled thereby.