Smaller electrolytic capacitors for implantable defibrillators

• US 6,275,729 B1
• Filed: 10/02/1998
• Issued: 08/14/2001
• Est. Priority Date: 10/02/1998
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Poplett, James M., Tong, Robert R., Barr, Alexander Gordon, OʼPhelan, Michael J.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/165,848
• Time in Patent Office: 1,047 Days
• Field of Search: 607/5, 29/250.3
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3975 Power supply A61N1/378 takes precedence
• CPC Class Codes: A61N 1/3981 High voltage charging circuitry
• CPC Class Codes: H01G 9/02 Diaphragms; Separators
• CPC Class Codes: H01G 9/045 based on aluminium
• CPC Class Codes: H01G 9/06 Mounting in containers
• CPC Class Codes: H01G 9/145 Liquid electrolytic capacitors H01G11/00 takes precedence

Abstract

Implantable defibrillators are implanted into the chests of patients prone to suffering ventricular fibrillation, a potentially fatal heart condition. A critical component in these devices is an aluminum electrolytic capacitors, which stores and delivers one or more life-saving bursts of electric charge to a fibrillating heart. These capacitors make up about one third the total size of the defibrillators. Unfortunately, conventional manufacturers of these capacitors have paid little or no attention to reducing the size of these capacitors through improved capacitor packaging. Accordingly, the inventors contravened several conventional manufacturing principles and practices to devise unique space-saving packaging that allows dramatic size reduction. One embodiment of the invention uses thinner and narrower separators and top and bottom insulative inserts to achieve a 330-volt operating, 390-volt surge, 190-microfarad, 30-Joule aluminum electrolytic capacitor which is 33 percent smaller than conventional capacitors having similar electrical traits.

Claims

1. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes;

at least one cylindrical electrolytic capacitor that has a nominal capacitance of at least 190 micro-farads, a voltage rating of at least 300 volts, and a total volume less than about 6 cubic-centimeters.

2. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes;

at least one aluminum electrolytic capacitor comprising a cylindrical active element that includes a capacitive assembly having one or more separators and one or more foil members, with one or more of the separators having a width and one or more of the foil members having a width that is at most 3.5 millimeters less than the width of one or more of the separators; and

at least one aluminum electrolytic capacitor comprising a cylindrical active element having a top and a bottom portion;

a cylindrical case at least partly encasing the active element and having a bottom interior surface adjacent the bottom portion of the active element and an opening adjacent the top portion of the active element;

a header positioned at least partly within the opening of the case; and

one or more insulative inserts positioned between the top portion of the active element and the header or between the bottom interior surface of the case and the bottom portion of the active element.

3. The system of claim 2 wherein one or more of the separators has a nominal thickness of 0.000787, 0.0005, or 0.00025 inches and comprises paper and wherein the separators are impregnated with a non-polymer-based electrolyte.

4. The system of claim 2, wherein the one capacitor further includes:

at least one foil that comprises;

first and second opposing sides each having one or more of cavities having an average depth less than one-half the foil thickness; and

two or more perforations through the foil.

5. The system of claim 4, wherein the average depth of the cavities is about one-third or one-fourth of the foil thickness.

6. The system of claim 4 wherein the average cross-sectional area of the perforations is about 2 to 100 times larger than the average cross-sectional area of the cavities.

7. The system of claim 4, wherein the one or more perforations include at least three perforations, wherein each of the perforations has an associated average maximum cross-sectional area between 500 square-microns and 32 square-millimeters, inclusive, and wherein at least one of the perforations has no alignment or mounting member extending through it.

8. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more capacitors, with each capacitor including;

one or more separators having a width;

and one or more foil members having a width that is at most 3.5 millimeters less than the width of one or more of the separators, with each of the one or more foil members comprising

first and second opposing sides each having one or more of cavities having an average depth less than one-half the foil thickness; and

one or more perforations through the foil.

9. The system of claim 8 wherein the average depth of the cavities is about one-third or one-fourth of the foil thickness.

10. The system of claim 8 wherein the perforations have an average cross-sectional area larger than an average cross-sectional area of the cavities.

11. The system of claim 8 wherein the average cross-sectional area of the perforations is about 2 to 100 times larger than the average cross-sectional area of the cavities.

12. The system of claim 8, wherein the perforations include at least three perforations, wherein each of the perforations has an associated average maximum cross-sectional area between 500 square-microns and 32 square-millimeters, inclusive;

and wherein at least one of the perforations has no alignment or mounting member extending through it.

13. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more electrolytic capacitors comprising;

a cylindrical active element having a top and a bottom portion, and including one or more foils each comprising;

first and second opposing sides, with each side having one or more of cavities having an average depth less than one-half the foil thickness; and

one or more perforations through the foil;

a cylindrical case at least partly encasing the active element and having a bottom interior surface adjacent the bottom portion of the active element and an opening adjacent the top portion of the active element;

a header positioned at least partly within the opening of the case; and

one or more insulative inserts positioned between the top portion of the active element and the header or between the bottom interior surface of the case and the bottom portion of the active element.

14. The system of claim 13, wherein the one or more perforations include at least three perforations, wherein each of the perforations has an associated average maximum cross-sectional area between 500 square-microns and 32 square-millimeters, inclusive, and wherein each of the three perforations has no alignment or mounting member extending through it.

15. The system of claim 13, wherein the one or more perforations include at least three perforations, wherein each of the perforations has an associated average maximum cross-sectional area between 500 square-microns and 32 square-millimeters, inclusive, and wherein the three perforations are not colinear.

16. The system of claim 13 wherein the header has a thickness less than about 2.5 millimeters.

17. The system of claim 16 wherein the case includes a circumferential seating groove which has been partially or completely flattened to reduce case height.

18. The system of claim 16 wherein the cylindrical active element has a mandrel or mandrel region which has a width or diameter less than about 2.5 millimeters.

19. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more cylindrical electrolytic capacitors comprising a cylindrical active element having a mandrel or mandrel region which has a width or diameter less than about 2.5 millimeters.

20. The system of claim 19, wherein each active element further comprises:

one or more anode foils, with each anode foil comprising;

first and second opposing sides each having one or more of cavities having an average depth less than one-half the foil thickness; and

one or more perforations through the foil.

21. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more capacitors, with each capacitor including;

one or more separators having a width;

and one or more foil members having a width that is at most 3.5 millimeters less than the width of one or more of the separators.

22. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more capacitors, with each capacitor including;

one or more separators having a width;

and one or more foil members having a width that is at most 3.5 millimeters less than the width of one or more of the separators, with each of the one or more foil members comprising

first and second opposing sides each having one or more of cavities having an average depth less than one-half the foil thickness; and

means, including one or more perforations through the foil, for allowing flow of a liquid through the foil, with at least one of the perforations having no mounting member extending through it.

23. An implantable cardiac rhythm management system comprising:

one or more leads for sensing electrical signals of a patient or for applying electrical energy to the patient;

a monitoring circuit for monitoring heart activity of the patient through one or more of the leads; and

a therapy circuit for delivering electrical energy through one or more of the leads to a heart of the patient, wherein the therapy circuit includes one or more capacitors, with each capacitor including;

one or more separators having a width;

and one or more foil members having a width that is at most 3.5 millimeters less than the width of one or more of the separators, with each of the one or more foil members comprising;

means, including one or more perforations through the foil, for allowing flow of a liquid through the foil, with at least one of the perforations having no mounting member extending through it;

first and second opposing surfaces; and

means, between the first and second opposing surfaces, for enhancing durability of the foil.