IMPLANTABLE CARDIAC PACEMAKER WITH BATTERY VOLTAGE-RESPONSIVE RATE

• US 3,825,016 A
• Filed: 02/28/1972
• Issued: 07/23/1974
• Est. Priority Date: 02/28/1972
• Status: Expired due to Term

• Current Assignee: Denis John Becker, Peter Gilbert Lale
• Original Assignee: Denis John Becker, Peter Gilbert Lale
• Inventors: Lale, Peter Gilbert, Becker, Denis John
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/229,687
• Time in Patent Office: 876 Days
• Field of Search: 128/419P,421,422
• US Class Current: 607/29
• CPC Class Codes: A61N 1/3708 for power depletion

Abstract

An implantable cardiac pacer including a voltage level detector for responding when the voltage of the pacer power source falls below a predetermined level. Response of the voltage detector gives a warning to the wearer in the form of increased pulse output rate.

Claims

1. An implantable cardiac pacer including a power source, pulse generating means connected to the power source to derive power therefrom for generating stimulating pulses at a first rate which is approximately equal to the normal heart beat rate and for generating stimulating pulses at a second rate appreciably higher than said first rate, output electrode means coupled to said pulse generating means to which the output of said pulse generating means is supplied, a pulse rate control circuit means which forms part of the pulse generating means normally controlling said pulse generating means for generating pulses at said first rate and which in the absence of an input thereto permits said pulse generating means to generate stimulating pulses at said second rate, and voltage detector means connected to the power source and responsive to the output voltage of the power source, the voltage detector means being coupled to the pulse rate control circuit means to supply an input to the pulse rate control circuit means only on detection of an output voltage at least as high as a predetermined voltage to cause the pacer to generate stimulating pulses at said first rate, whereby when said voltage detector means fails to detect the predetermined voltage, it fails to generate an input for the pulse rate control circuit and the pulse generating means generates stimulating pulses at said second rate.

2. An implantable cardiac pacer as claimed in claim 1 wherein the first rate is substantially 70 pulses per minute and the second rate is substantially 90 pulses per minute.

3. An implantable cardiac pacer as claimed in claim 2 which is a demand pacer and which has input electrode means which receive sinus signals from the heart, a trigger circuit means coupled between said input electrode means and said pulse rate control circuit to actuate said pulse rate control circuit to inhibit operation of said pulse generating means on receipt of such sinus signals to prevent generation of stimulating pulses, a feedback circuit means coupled between the output of said pulse generating means and said trigger circuit for controlling said pulse rate control circuit for controlling said pulse generating means in response to output pulses fed back through said feedback circuit means for generating pulses at said first rate, said voltage detector means being connected in said feedback circuit means for blocking supply of said output pulses through said feedback circuit means upon failure to detect the predetermined voltage.

4. An implantable cardiac pacer as claimed in claim 3 in which said voltage detector means comprises a direct-coupled amplifier in series in the feedback circuit means and including an output transistor, an internal feedback circuit means from the output transistor to the amplifier input, whereby feedback by way of the internal feedback circuit means is effective to maintain a constant bias at the output transistor, regardless of supply voltage, so that output pulse amplitude from the amplifier is dependent on supply voltage, said trigger circuit being responsive only to those output pulses from said amplifier which are above a predetermined amplitude.