System and method for treating dilated cardiomyopathy using end diastolic volume (EDV) sensing

• US 6,314,322 B1
• Filed: 03/02/1998
• Issued: 11/06/2001
• Est. Priority Date: 03/02/1998
• Status: Expired due to Term

• Current Assignee: Abiomed, Inc. (Johnson & Johnson)
• Original Assignee: Abiomed, Inc. (Johnson & Johnson)
• Inventors: Rosenberg, Meir
• Primary Examiner(s): Layno, Carl
• Application Number:
  US09/032,697
• Time in Patent Office: 1,345 Days
• Field of Search: 607/6, 607/9, 607/5, 607/24, 607/119, 607/17, 600/374, 600/390
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• 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
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36528 the parameter being measured by means of ultrasound
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration

Abstract

A system for controlling end diastolic volume of the heart is disclosed. The system includes an EDV sensor constructed and arranged to measure a parameter related to the end diastolic volume of the heart, and a heart stimulator, responsive to the EDV sensor, constructed and arranged to invoke systole when the measured parameter reaches a predetermined level, the parameter reaching that level prior to termination of diastole. Preferably, the heart stimulator may be a pacemaker. The EDV sensor may be any sensor constructed to measure a parameter related to the end diastolic volume of the heart, or another selected physiological or patho-physiological condition of the heart, including a strain sensor, a stress sensor, a dimension sensor, an impedance sensor, an optical sensor, a microwave sensor, or another sensor constructed to measure a parameter related to the end diastolic volume of the heart, or another selected physiological or patho-physiological condition of the heart. A method for controlling end diastolic volume of the heart including the steps of measuring a parameter that is related to the end diastolic volume of the heart, and invoking systole before termination of diastole when the measured parameter reaches a predetermined level is also disclosed.

Claims

1. A system for controlling end diastolic volume (EDV) of a natural heart to treat dilated cardiomyopathy comprising:

an EDV sensor constructed and arranged to measure a parameter related to the end diastolic volume of the heart; and

a heart stimulator to treat dilated cardiomyopathy, responsive to said EDV sensor, constructed and arranged to invoke systole when said parameter reaches a selected level, said parameter reaching said selected level prior to termination of diastole, and thereby inducing early systolic ejection before a maximum diastolic volume is reached.

2. The system of claim 1, wherein said heart stimulator is a pacemaker.

3. The system of claim 1, wherein said EDV sensor comprises a strain sensor.

4. The system of claim 3, wherein said strain sensor includes an expandable element implanted on a wall of the heart.

5. The system of claim 4, wherein said expandable element at least partially encircles the heart.

6. The system of claim 1, wherein said EDV sensor includes a stress sensor.

7. The system of claim 6, wherein said stress sensor comprises:

a transmitter constructed and arranged to emit sound waves into the heart; and

a receiver constructed and arranged to detect sound waves reflected from the heart.

8. The system of claim 7, wherein said transmitter and said receiver comprise at least one piezoelectric crystal.

9. The system of claim 8, wherein said stress sensor further comprises:

a coupling medium attached to said piezoelectric crystal, said coupling medium being implantably attachable to a wall of the heart.

10. The system of claim 7, wherein said receiver is constructed and arranged to detect multiple sound waves reflected from tissue interfaces in the heart.

11. The system of claim 7, wherein said stress sensor is further constructed to measure stress within a myocardium of the heart, said stress sensor employing the following equation:

$\mathrm{\sigma <br><br>}=\frac{\mathrm{Pr}}{\mathrm{\tau <br><br>}}$

where σ

is the stress, P is ventricular pressure, r is ventricular radius and τ

is ventricular wall thickness.

12. The system of claim 11, wherein said stress sensor is further constructed to calculate said ventricular thickness (τ

) as a product of a time between a first reflected signal and a second reflected signal and speed of sound within the heart wall.

13. The system of claim 11, wherein said stress sensor is further constructed to calculate said ventricular radius (r) by employing the following equation:

$r=\frac{T_E-T_D}{4}<br><br>C_B$

where T_E is detected time of a third reflected signal, T_D is detected time of a second reflected signal, and C_B is speed of sound in blood.

14. The system of claim 1, wherein said EDV sensor comprises a dimension sensor.

15. The system of claim 14, wherein said dimension sensor comprises:

a band that at least partially encircles the heart to monitor a circumference of the heart.

16. The system of claim 14, wherein said dimension sensor includes a band that at least partially encircles the heart, said band including a selected fixed circumference.

17. The system of claim 16, wherein said band is expandable through a range of circumferences, said range including said selected circumference.

18. The system of claim 1, wherein said EDV sensor includes an impedance sensor.

19. A method for controlling end diastolic volume (EDV) of a natural heart to treat dilated cardiomyopathy, comprising the steps of:

measuring a parameter related to the end diastolic volume of the heart by employing a EDV sensor; and

invoking systole, by employing a heart stimulator to treat dilated cardiomyopathy, before termination of diastole when said parameter reaches a predetermined level, to induce early systolic ejection before a maximum diastolic volume is needed.

20. The method of claim 19, wherein said measuring step comprises measuring strain experienced by an expandable element implanted on a wall of the heart.

21. The method of claim 19, wherein said measuring step comprises the step of:

measuring stress in a wall of the heart.

22. The method of claim 21, wherein said stress measuring step includes the steps of:

emitting from a transmitter sound waves into the heart; and

detecting by a receiver sound waves reflected from the heart.

23. The method of claim 22, wherein said emitting and detecting steps include the step of:

introducing said sound waves into a coupling medium implantably attached to the heart wall.

24. The method of claim 22, wherein said detecting step comprises the step of:

detecting multiple sound waves reflected from tissue interfaces in the heart.

25. The method of claim 24, wherein said stress measuring step includes the step of:

calculating myocardium stress by employing the following equation;

$\mathrm{\sigma <br><br>}=\frac{\mathrm{Pr}}{\mathrm{\tau <br><br>}}$

where σ

is the stress, P is ventricular pressure, r is ventricular radius and τ

is ventricular wall thickness.

26. The method of claim 25, wherein said stress measuring step further includes the step of:

calculating said ventricular radius (r) by employing the following equation;

$r=\frac{T_E-T_D}{4}<br><br>C_B$

where T_E is detection time of a third reflected signal, T_D is detected time of a second reflected signal, and C_B is the speed of sound in blood.

27. The method of claim 25, wherein said measuring step further comprises the step of:

calculating said ventricular thickness (τ

) as a product of an elapsed time between a first reflected signal and a second reflected signal and speed of sound within the heart wall.

28. The method of claim 19, wherein said measuring step comprises the step of measuring a dimension of the heart.

29. The method of claim 19, wherein said measuring step comprises measuring impedance of a region of the heart.

30. A system for controlling end diastolic volume (EDV) of a natural heart comprising:

a stress sensor constructed and arranged to measure a parameter related to the end diastolic volume of the heart, said stress sensor including,

a transmitter constructed and arranged to emit sound waves into the heart, and

a receiver constructed and arranged to detect sound waves reflected from tissue interfaces in the heart; and

a pacemaker, responsive to said stress sensor, constructed and arranged to invoke systole when said parameter reaches a selected level, said parameter reaching said selected level prior to termination of diastole.