Method and apparatus for assessing ventricular contractile status

• US 6,994,676 B2
• Filed: 04/30/2003
• Issued: 02/07/2006
• Est. Priority Date: 04/30/2003
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Mulligan, Lawrence J., Gebhardt, Ursula
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US10/426,425
• Publication Number:
  US 20040220638A1
• Time in Patent Office: 1,014 Days
• Field of Search: 607 18- 19, 607/23, 600/508, 600/513, 600/527, 600/481, 600485-486, 600/488
• US Class Current: 600/508
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy

Abstract

Methods and devices for improving ventricular contractile status of a patient suitably exploit changes in ventricular pressure and/or dP/dt_max to provide and/or optimize a response to a patient. The ventricular pressure may be appropriately correlated to intracellular calcium regulation, which is indicative of contractile status. To assess ventricular contractile status, the device suitably observes a cardiac perturbation of the patient and measures force interval potentiation following the perturbation. The contractile potentiation can then be stored and/or quantified in the implantable medical device to determine the ventricular contractile status of the patient, and an appropriate response may be provided to the patient as a function of the ventricular contractile status. Examples of responses may include administration of drug or neuro therapies, modification of a pacing rate, or the like. Force interval potentiation may also be used to optimize or improve a parameter for a response provided by the implantable medical device.

Claims

1. A method of assessing ventricular contractile status of a patient in an implantable medical device, the method comprising the steps of:

observing a cardiac perturbation of the patient at the implantable medical device;

measuring the contractile potentiation following the perturbation at the implantable medical device;

quantifying the contractile potentiation in the implantable medical device to determine the ventricular contractile status of the patient; and

wherein the quantifying step comprises calculating a recirculation fraction as a function of the measured potentiation.

2. The method of claim 1 wherein the identifying step comprises inducing the perturbation in the patient from the implantable medical device.

3. The method of claim 1 wherein the cardiac perturbation comprises an extra-systolic beat.

4. The method of claim 1 wherein the cardiac perturbation comprises a premature ventricular contraction.

5. The method of claim 1 wherein the quantifying step comprises calculating a potentiation ratio as a function of the measured potentiation.

6. The method of claim 1 wherein the quantifying step comprises

calculating a potentiation ratio as a function of the measured potentiation.

7. The method of claim 1 further comprising The step of storing data representing the contractile potentiation in the implantable medical device.

8. The method of claim 7 further comprising the steps of repeating the observing, measuring, quantifying and storing steps to identify changes in ventricular contractile status over time.

9. A method of assessing ventricular contractile status of a patient in an implaritable medical device, the method comprising the steps of;

observing a cardiac perturbation of the patient at the medical device;

measuring ventricular contractile potentiation following the perturbation at the medical device;

processing the contractile potentiation in the medical device to determine a representation of the ventricular contractile status of the patient;

storing the representation in a digital memory located within the implantable medical device; and

repeating the observing, measuring, processing and storing steps to identify changes in the ventricular contractile status over time.

10. The method of claim 9 wherein the representation comprises a recirculation fraction.

11. The method of claim 9 wherein the representation comprises a potentiation ratio.

12. A medical device implanted in a patient, the device comprising:

means for observing a cardiac perturbation in the patient;

means for measuring contractile potentiation following the perturbation;

means for quantifying the contractile potentiation to obtain a data representation of the ventricular contractile status of the patient; and

means for inducing the cardiac perturbation in the patient from the implantable medical device,

wherein the data-representation comprises a recirculation fraction.

13. A medical device implanted in a patient, the device comprising:

means for observing a cardiac perturbation in the patient;

means for measuring contractile potentiation following the perturbation;

means for quantifying the contractile potentiation to obtain a data representation of the ventricular contractile status of the patient; and

means for storing the data representation.

14. The medical device of claim 13 wherein the data representation comprises a potentiation ratio.