Exercise-responsive cardiac pacemaker lead

• US 4,726,383 A
• Filed: 10/02/1986
• Issued: 02/23/1988
• Est. Priority Date: 05/19/1982
• Status: Expired due to Term

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Fearnot, Neal E., Cook, William A., Geddes, Leslie A.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/915,887
• Time in Patent Office: 509 Days
• Field of Search: 128/692, 128/784-786, 128/419 PG
• US Class Current: 607/21
• CPC Class Codes: A61N 1/3655 controlled by body or blood temperature

Abstract

An exercise-responsive cardiac pacemaker is provided which physiologically controls the stimulation rate of a heart by sensing the venous blood temperature in the right ventricle of the heart. A temperature sensing means which includes a thermistor produces an output signal which is sent to an algorithm implementing means for implementing the output signal by an algorithm which represents the mathematical function between venous blood temperature in the right ventricle and heart rate in a normally functioning heart. The algorithm implementing means produces an output signal which is variable between a maximum and minimum level corresponding to the desired maximum and minimum levels of heart rate in a normally functioning heart. The algorithm implementing means is also programmable by telemetry after implantation. A cardiac pacemaker is connected to the algorithm implementing means and is responsive thereto in order to variably control the stimulation rate of the heart.

Claims

1. A catheter-based sensor and stimulus means for an exercise responsive cardiac pacemaker including pacing circuitry for providing electrical stimulation of a heart based upon the level of muscular exertion, comprising:

a thermistor for sensing blood temperature, said thermistor having a pair of electrical leads;

a stimulus means for applying an electrical stimulus to a heart;

a catheter associated with said thermistor and said stimulus means, said catheter having at least one lumen therethrough; and

an electrical conductor means for operatively connecting said stimulus means and said thermistor to control circuitry for said exercise responsive cardiac pacemaker in such manner that the frequency of said electrical stimulus is controlled by said blood temperature as sensed by said thermistor, said electrical conductor means including a bifilar coil wire connected to said stimulus means, a pair of bifilar coil wires associated with said electrical leads of said thermistor, and a pair of rigid conductive tubing sections joining said pair of bifilar coil wires to said pair of leads, respectively,

wherein said thermistor is coated with glass, encased within epoxy and received in a lumen of said catheter which is at least partially filled with an elastomer, said stimulus means is mounted on the distal end of said catheter, and wherein said thermistor is received within said lumen and located relative to said stimulus means such that when said stimulus means is positioned within said heart for electrical stimulation thereof, said thermistor is centrally positioned within the right ventricle of said heart.

2. The apparatus of claim 1 wherein said catheter includes first, second and third lumens, said first lumen for operatively coupling therethrough said stimulus means with said control circuitry and said second and third lumens for operatively coupling therethrough said thermistor and said control circuitry.

3. The apparatus of claim 2 wherein said stimulus means is an electrode.

4. A catheter based sensor and stimulus means for an exercise responsive cardiac pacemaker including pacing circuitry for providing electrical stimulation of a heart based upon the level of muscular exertion, comprising:

a glass bead thermistor having a pair of electrical leads, said thermistor being located in the flow path of blood;

a stimulus means for applying an electrical stimulus to the heart;

a catheter associated with said thermistor and said stimulus means, said catheter having at least one lumen therethrough; and

an electrical conductor means for operatively connecting said stimulus means and said thermistor to control circuitry for said exercise responsive cardiac pacemaker in such matter that the frequency of said electrical stimulus is controlled by said blood temperature as sensed by blood thermistor, said electrical conductor means including a pair of electrical wires associated with said electrical leads of said thermistor and a pair of rigid conductor tubing sections joining said pair of electrical wires to said pair of leads, respectively,

wherein said thermistor is received in a lumen of said catheter which is at least partially filled with elastomer, said stimulus means is mounted on the distal end of said catheter, and wherein said thermistor is received within said lumen and located relative to said stimulus means such that when said stimulus means is positioned within said heart for electrical stimulation thereof, said thermistor is located in the flow path of blood.

5. The apparatus of claim 4 wherein said stimulus means is mounted on the distal end of said catheter and said thermistor is received within said lumen.

6. The apparatus of claim 5 wherein said thermistor is located relative to said stimulus means such that when said stimulus means is positioned within said heart for electrical stimulation thereof, said thermistor is centrally positioned within the right ventricle of said heart.

7. The apparatus of claim 6 wherein said catheter includes first, second and third lumens, said first lumen for operatively coupling therethrough said stimulus means with said control circuitry and said second and third lumens for operatively coupling therethrough said thermistor and said control circuitry.

8. The apparatus of claim 7 wherein said stimulus means is an electrode.