Methods for measuring impedances associated with the heart

• US 8,868,186 B2
• Filed: 10/30/2007
• Issued: 10/21/2014
• Est. Priority Date: 05/14/2001
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Kroll, Mark W.
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US11/928,296
• Publication Number:
  US 20080058669A1
• Time in Patent Office: 2,548 Days
• Field of Search: 600/547, 600/549, 600/554, 600/455, 600/374, 607/28, 607/9, 607/23, 607/5, 607/3, 607/8, 607/20, 607/24
• US Class Current: 607/28
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61N 1/0504 Subcutaneous electrodes
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An exemplary method includes introducing current between a first pair of electrodes configured for placement internally in a patient, triggering a potential measurement between a second pair of electrodes configured for placement internally in a patient wherein communication of a signal through the patient allows for proper triggering, measuring potential between the second pair of electrodes and, based at least in part on the measuring and the introducing, determining a cardiac condition. Other exemplary methods, devices, systems, etc., are also disclosed.

Claims

1. A method comprising:

introducing current between a first pair of electrodes configured for placement internally in a patient, the first pair of electrodes being from a unitary subcutaneous cardiac defibrillation device, wherein the unitary subcutaneous cardiac defibrillation device is leadless and comprises a housing containing a power supply, capacitor, and operational cardiac defibrillation circuitry;

triggering a potential measurement between a second pair of electrodes configured for placement internally in a patient, wherein the second pair of electrodes is from an implantable cardiac device, wherein wireless communication between the unitary subcutaneous cardiac defibrillation device and the implantable cardiac device allows for proper triggering, wherein the implantable cardiac device comprises a subcutaneous housing and a lead connected to the housing, wherein the lead is implanted within the heart, wherein at least one of the second pair of electrodes is disposed on the lead, and wherein the unitary subcutaneous cardiac defibrillation device is discrete from the implantable cardiac device;

measuring potential between the second pair of electrodes; and

based at least in part on the measuring and the introducing, determining a cardiac condition wherein the unitary subcutaneous cardiac defibrillation device performs the introducing and the implantable cardiac device performs the measuring.

2. The method of claim 1 wherein the communication includes communicating a timing signal to synchronize two timers.

3. The method of claim 1 wherein the communication includes communicating a trigger signal that thereby commences the measuring.

4. The method of claim 1 wherein the communication occurs through use of an external device.

5. The method of claim 1 wherein the determining includes determining a cardiac condition selected from a group consisting of chamber volume, cardiac output, and ventricular wall thickness.

6. The method of claim 1 where the introducing comprises establishing a current path between the first pair of electrodes, and wherein the measuring comprises measuring potential between a right ventricular electrode and the housing of the implantable cardiac device.

7. The method of claim 1 wherein the implantable cardiac device is a multi-chamber stimulation and shock therapy device.

8. A method comprising:

introducing current between a first pair of electrodes configured for placement internally in a patient, the first pair of electrodes being from a unitary subcutaneous cardiac defibrillation device, wherein the unitary subcutaneous cardiac defibrillation device is leadless and comprises a housing containing a power supply, capacitor, and operational cardiac defibrillation circuitry;

triggering an impedance measurement between a second pair of electrodes configured for placement internally in a patient, wherein the second pair of electrodes is from an implantable cardiac device, wherein wireless communication between the unitary subcutaneous cardiac defibrillation device and the implantable cardiac device allows for proper triggering, wherein the implantable cardiac device comprises a subcutaneous housing and a lead connected to the housing, wherein the lead is implanted within the heart, wherein at least one of the second pair of electrodes is disposed on the lead, and wherein the unitary subcutaneous cardiac defibrillation device is discrete from the implantable cardiac device;

measuring impedance between the second pair of electrodes; and

based at least in part on the measuring and the introducing, determining a cardiac condition wherein the unitary subcutaneous cardiac defibrillation device performs the introducing and the implantable cardiac device performs the measuring.

9. The method of claim 8 wherein the communication includes communicating a timing signal to synchronize two timers.

10. The method of claim 8 wherein the communication includes communicating a trigger signal that thereby commences the measuring.

11. The method of claim 8 wherein the communication occurs through use of an external device.

12. The method of claim 8 wherein the determining includes determining a cardiac condition selected from a group consisting of chamber volume, cardiac output, and ventricular wall thickness.

13. The method of claim 8 wherein the wireless communication conducts signals through body tissue and/or fluid.

14. The method of claim 8 wherein the introducing comprises establishing a current path between the first pair of electrodes, and wherein the measuring comprises measuring impedance between a right ventricular electrode and the housing of the implantable cardiac device.

15. The method of claim 8 wherein the implantable cardiac device is a multi-chamber stimulation and shock therapy device.