Implantable device for delivering cardiac drug therapy

• US 8,275,456 B2
• Filed: 06/20/2006
• Issued: 09/25/2012
• Est. Priority Date: 11/12/2002
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Girouard, Steven D., Zhu, Qingsheng
• Primary Examiner(s): Lavert, Nicole F
• Application Number:
  US11/425,263
• Publication Number:
  US 20060247686A1
• Time in Patent Office: 2,289 Days
• Field of Search: 600/509, 600/517, 607/3
• US Class Current: 607/3
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/358 Detecting ST segments
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/36507 controlled by gradient or slope of the heart potential
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/36592 controlled by the heart rate variability

Abstract

An implantable medical device in which an electrogram is recorded and analyzed in order to detect changes indicative of cardiac ischemia. Cardiac ischemia may be detected by recording an electrogram from a sensing channel of the device and comparing the recorded electrogram with a reference electrogram. If cardiac ischemia is detected, a cardiac drug such as a thrombolytic agent is delivered.

Claims

1. An implantable cardiac device, comprising:

a sense amplifier for receiving an electrogram signal from an electrode;

circuitry for storing a reference electrogram;

circuitry configured to record an electrogram received by the sense amplifier and to detect a change in the recorded electrogram indicative of cardiac ischemia by comparing the recorded electrogram with the reference electrogram, wherein the circuitry is further configured to perform the comparison by passing the recorded electrogram through a matched filter that cross-correlates the recorded electrogram with the reference electrogram;

a minute ventilation sensor for measuring a patient'"'"'s respiratory rate;

a drug delivery apparatus for delivering a quantity of a cardiac drug; and

,

circuitry configured to actuate the drug delivery apparatus and further configured to initiate drug delivery only if both of the following conditions are met;

     1) cardiac ischemia is detected from the recorded electrogram, and

     2) the measured respiratory rate is above a specified threshold.

2. The device of claim 1 wherein the drug delivery apparatus includes a catheter.

3. The device of claim 2 wherein the drug delivery apparatus includes a drug reservoir and a pump for pumping a quantity of drug into a lumen of the catheter.

4. The device of claim 3 further comprising a header and wherein the pump and drug reservoir are located in the header of the device.

5. The device of claim 1 wherein the circuitry configured to detect a change in the recorded electrogram quantifies the degree of ischemia and further wherein the circuitry configured to cause delivery of a cardiac drug does so only when the degree of ischemia is above a programmable threshold value.

6. The device of claim 1 wherein the cardiac drug is a thrombolytic drug.

7. The device of claim 1 further comprising an accelerometer for measuring a patient'"'"'s activity level and wherein the circuitry configured to actuate the drug delivery apparatus does so only if the measured activity level is below a specified threshold value.

8. The device of claim 1 further comprising a pulse generator for delivering pacing pulses and wherein the circuitry configured to record an electrogram is configured to record an evoked response to a pacing pulse.

9. A method for operating a cardiac device implanted in a patient, comprising:

sensing intrinsic cardiac activity;

recording an electrogram from the sensed cardiac activity;

detecting cardiac ischemia by comparing the recorded electrogram with a reference electrogram, wherein the comparison is performed by passing the recorded electrogram through a matched filter that cross-correlates the recorded electrogram with the reference electrogram;

measuring the patient'"'"'s respiratory rate; and

,

delivering a cardiac drug and initiating cardiac drug delivery only if both of the following conditions are met;

     1) cardiac ischemia is detected from the recorded electrogram, and

     2) the measured respiratory rate is above a specified threshold.

10. The method of claim 9 further comprising delivering the cardiac drug through a catheter.

11. The method of claim 10 further comprising pumping the cardiac drug from a reservoir.

12. The method of claim 11 wherein the reservoir is located in a header of the cardiac device.

13. The method of claim 9 further comprising quantifying the degree of ischemia and delivering a cardiac drug only when the degree of ischemia is above a programmable threshold value.

14. The method of claim 9 wherein the cardiac drug is a thrombolytic drug.

15. The method of claim 9 further comprising:

measuring the patient'"'"'s activity level; and

,

delivering a cardiac drug only when an ischemic condition is detected from the recorded electrogram and the measured activity level is below a specified threshold value.

16. The method of claim 9 wherein the recorded electrogram is an evoked response to a pace.