System for cardiac pacing

• US 4,895,152 A
• Filed: 07/14/1988
• Issued: 01/23/1990
• Est. Priority Date: 12/11/1985
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Telectronics Incorporated
• Inventors: Schroeppel, Edward A., Callaghan, Frank J.
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/219,806
• Time in Patent Office: 558 Days
• Field of Search: 128/419 PO, 128/419 PT, 128/984, 128/786, 128/903
• US Class Current: 607/13
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

A system is provided for cardiac pacing, in which the output levels of the electrical stimulus pulses are responsive to the detection or non-detection of cardiac pacer evoked potentials. A pulse generator is provided for emitting electrical stimulus pulses at variable output levels. A pulse to pulse interval and an evoked response sensing period are provided. At the beginning of the pulse to pulse interval, an electrical stimulus having a first output level is emitted. If no evoked response is sensed during the sensing period, then an electrical stimulus at a selected maximum output level is emitted and, thereafter, the next electrical stimulus pulse is emitted at a second output level that is greater than the first output level. If a predetermined number of evoked responses are sensed during the sensing periods following the emission of stimulation pulses at other than the maximum output level, then the output level of the next electrical stimulus is decreased, but not to below a selected minimum output level.

Claims

1. The method of cardiac pacing and sensing which comprises the steps of:

providing a pulse generator for emitting an electrical stimulus;

providing a cardiac pacing lead for connection to said pulse generator and having a first electrode at its distal end and a spaced, second electrode free of electrical connection to said first electrode;

providing an output capacitor;

positioning said lead in a heart chamber;

periodically emitting an electrical stimulus having a first polarity from said first electrode to stimulate cardiac contraction;

discharging an electrical charge, having a polarity that is opposite to the first polarity of the electrical stimulus, from said output capacitor through the heart muscle via said first electrode immediately following the emission of said electrical stimulus, whereby the post stimulation potential of said first electrode is reduced and sensing of an evoked response is enhanced;

thereafter sensing said evoked response by said second electrode carried by said lead and spaced from said first electrode and free of electrical connection thereto; and

transmitting said sensed evoked response to a point of use.

2. A method as described in claim 1, including the steps of providing telemetering means, digitizing the sensed response, storing the digitized response, and transmitting the stored digitized response, upon command of a programmer, to said telemetering means for observing the stored response externally.

3. The method of cardiac pacing and sensing which comprises the steps of:

providing a pulse generator for emitting an electrical stimulus;

providing a cardiac pacing lead for connection to said pulse generator and having a tip electrode at its distal tip and a spaced ring electrode free of electrical connection to said tip electrode;

providing an output capacitor;

positioning said lead in a heart chamber;

periodically emitting an electrical stimulus having a first polarity from said tip electrode carried on the distal tip of said lead to stimulate cardiac contraction;

discharging an electrical charge, having a polarity that is opposite to the first polarity of the electrical stimulus, from said output capacitor through the heart muscle via said first electrode immediately following the emission of said electrical stimulus, whereby the post stimulation potential of said first electrode is reduced and sensing of an evoked response is enhanced;

thereafter detecting an electric potential response evoked by said stimulus pulse, indicating said muscular contraction, by a ring electrode carried by said lead and spaced from said tip electrode and free of electrical connection thereto; and

transmitting said digital response to a point of use.

4. A method as described in claim 3, including the steps of providing telemetering means, digitizing the sensed response, storing the digitized response, and transmitting the stored digitized electric potential response, upon command of a programmer, to said telemetering means for observing the stored electric potential response externally.

5. The method of cardiac pacing and sensing which comprises the steps of:

providing a pulse generator for emitting an electrical stimulus;

providing a cardiac pacing lead for connection to said pulse generator and having a tip electrode at its distal tip and a spaced ring electrode free of electrical connection to said tip electrode;

providing an output capacitor;

positioning said lead in a heart chamber;

periodically emitting an electrical stimulus having a first polarity from said tip electrode carried on the distal tip of said lead to stimulate cardiac contraction;

discharging an electrical charge, having a polarity that is opposite to the first polarity of the electrical stimulus, from said output capacitor through the heart muscle via said tip electrode immediately following the emission of said electrical stimulus, whereby the post stimulation potential of said first electrode is reduced and sensing of an evoked response is enhanced;

thereafter detecting an electric potential response evoked by said pulse, indicating said muscular contraction, by said ring electrode; and

telemetering the detected electric potential response to an external receiver.

6. Apparatus for cardiac pacing and sensing, which comprises;

a cardiac pacing lead having a tip electrode on its distal end and a ring electrode spaced from said tip electrode;

said cardiac pacing lead being adapted for positioning within a heart chamber;

an output capacitor coupled to said tip electrode;

means for transmitting to said tip electrode an electrical stimulus having a first polarity to stimulate cardiac contraction;

means for discharging an electrical charge, having a polarity that is opposite to the first polarity of the electrical stimulus, from said output capacitor through the heart muscle via said first electrode immediately following the emission of said electrical stimulus, whereby the post stimulation potential of said first electrode is reduced and sensing of an evoked response is enhanced;

sensing means, coupled to said ring electrode, for detecting said evoked response; and

means for transmitting the detected evoked response to a point of use.

7. Apparatus as described in claim 6, including means for providing a charge dump signal;

said discharging means comprising a FET and a resistor that is shorted by the FET in response to said charge dump signal to provide rapid discharge of said capacitor.