Method and apparatus for administering cardiac electrotherapy dependent on mechanical and electrical cardiac activity

• US 5,271,392 A
• Filed: 01/27/1992
• Issued: 12/21/1993
• Est. Priority Date: 08/24/1990
• Status: Expired due to Term

• Current Assignee: Bozidar Ferek-Petric
• Original Assignee: Siemens-Elema AB (Siemens AG)
• Inventors: Ferek-Petric, Bozidar
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US07/827,055
• Time in Patent Office: 694 Days
• Field of Search: 128/419 D, 128/419 PG
• US Class Current: 607/14
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585

Abstract

A method for administering cardiac electrotherapy and an implantable electrotherapy apparatus employ myocardial tensiometry to measure contractions of the heart muscle. The system includes a tensiometric element disposed at a location subject to bending due to cardiac contractions, the tensiometric element consisting either of piezoelectric material or variable resistivity material, the mechanical stresses to which the tensiometric element is subjected causing the element to produce a voltage or a resistivity variation comparable in frequency and amplitude to the contractions. The tensiometric element may be in the form of a strip disposed on a surface of a patch electrode, of the type suitable for use in an implantable defibrillator, or may be a strip or a tube located at the bend of a J-shaped pacing lead, of the type implantable in the atrium or in the ventricle in a cardiac pacemaker system. Electrical cardiac activity due to repolarization of the cardiac tissue is also sensed, and the frequency of the electrical activity, the frequency of the mechanical activity due to the cardiac contractions, and the amplitude of the voltage signal produced by the tensiometric element are used to control the administration of electrotherapy to the cardiac tissue.

Claims

1. A method for administering electrotherapy to cardiac tissue, said cardiac tissue exhibiting mechanical activity having a mechanical frequency and electrical activity having an electrical frequency, said method comprising the steps:

sensing in vivo the electrical frequency of said electrical activity;

tensiometrically sensing in vivo the mechanical frequency of said mechanical activity and generating a voltage amplitude corresponding to said mechanical activity;

comparing the sensed electrical and mechanical frequencies;

if the sensed electrical and mechanical frequencies are equal, comparing the equal frequencies to a minimum tachycardia frequency;

if said equal frequencies exceed said minimum tachycardia frequency, comparing said voltage amplitude with a maximum pathological tachycardia voltage; and

if said voltage amplitude is less than said maximum pathological tachycardia voltage, administering anti-tachycardia electrotherapy to said cardiac tissue.

2. A method as claimed in claim 1 wherein the step of administering anti-tachycardia electrotherapy to said cardiac tissue is further defined by administering an anti-tachycardia pacing sequence to said cardiac tissue.

3. A method as claimed in claim 1 comprising the additional steps of:

sensing said electrical frequency with an adjustable sensitivity; and

if the sensed electrical frequency is higher than the sensed mechanical frequency, decreasing said sensitivity.

4. A method as claimed in claim 1 comprising the additional steps of:

sensing said electrical frequency with an adjustable sensitivity; and

if the sensed mechanical frequency is higher than the sensed electrical frequency, increasing said sensitivity.

5. An apparatus for administering electrotherapy to cardiac tissue, said cardiac tissue exhibiting mechanical activity having a mechanical frequency and electrical activity having an electrical frequency, said apparatus comprising:

means for sensing in vivo the electrical frequency of said electrical activity;

tensiometric means for sensing in vivo the mechanical frequency of said mechanical activity and for generating a voltage amplitude corresponding to said mechanical activity;

means for comparing the sensed electrical and mechanical frequencies;

means for comparing the sensed electrical and mechanical frequencies to a minimum tachycardia frequency if the sensed electrical and mechanical frequencies are equal;

means for comparing said voltage amplitude with a maximum pathological tachycardia voltage if the sensed electrical and mechanical frequencies are equal and exceed said maximum tachycardia frequency; and

means for administering anti-tachycardia electrotherapy to said cardiac tissue if said sensed voltage amplitude is less than said maximum pathological tachycardia voltage.

6. An apparatus as claimed in claim 5 wherein said means for administering anti-tachycardia electrotherapy to said cardiac tissue is a means for administering an anti-tachycardia pacing sequence to said cardiac tissue.

7. An apparatus as claimed in claim 5 wherein said means for sensing in vivo the electrical frequency of said cardiac activity includes an amplifier having an adjustable sensitivity;

and

means for decreasing the sensitivity of said amplifier if the sensed electrical frequency is higher than the sensed mechanical frequency.

8. An apparatus as claimed in claim 5 wherein said means for sensing in vivo the electrical frequency of said cardiac activity includes an amplifier having an adjustable sensitivity, and means for increasing the sensitivity of said amplifier if the sensed mechanical frequency is higher than the sensed electrical frequency.