Mechanism for detecting coronary ischemia

1. A system for detecting myocardial ischemia comprising:

an implantable device having one or more leads connected thereto;

at least one electrode on a lead of the device, the electrode configured to stimulate the heart;

at least two oximetry sensors on one or more leads of the device, the at least two oximetry sensors configured to measure oxygen saturation in a coronary sinus; and

a microprocessor in the implantable device programmed to:

run a stress test on the heart by stimulating the heart with the electrode;

record data obtained from the at least two oximetry sensors during the stress test;

determine whether there is myocardial ischemia based upon the recorded data; and

determine a location of the myocardial ischemia based upon a difference in the oxygen saturation measured at the at least two oximetry sensors.

2. The system of claim 1 , wherein the microprocessor is configured to determine whether there is myocardial ischemia by determining whether data recorded from the sensor during the stress test has exceeded a threshold value.

3. The system of claim 2 , wherein the microprocessor is further configured to establish a baseline from the recorded data and set the threshold value using the baseline.

4. The system of claim 1 , further comprising an alarm connected to the implantable device and configured to transmit a warning signal if myocardial ischemia is detected.

5. The system of claim 1 , wherein the implantable device is a pacemaker or defibrillator.

6. The system of claim 1 , further comprising a heating or cooling element on the lead.

7. A method of detecting myocardial ischemia comprising:

measuring oxygen saturation of blood in a coronary sinus with at least two oximetry sensors on one or more leads of an implantable device;

recording data obtained from the sensor in a memory of the implantable device to establish a baseline;

performing a stress test with the implantable device;

measuring the oxygen saturation with the sensors during the stress test;

comparing the oxygen saturation measured during the stress test with the baseline to detect whether there is myocardial ischemia; and

determining a location of the myocardial ischemia based upon a difference in the oxygen saturation measured at the at least two oximetry sensors.

8. The method of claim 7 , wherein performing a stress test comprises pacing the heart with an electrode coupled to the device at a rate of at least 100 beats per minute.

9. The method of claim 7 , wherein performing a stress test comprises pacing the heart at a first rate for a set period of time and then, if no ischemia has been detected, increasing the rate of pacing.

10. The method of claim 9 , further comprising stopping the stress test if the pacing rate is greater than a predetermined amount and no ischemia has been detected.

11. The method of claim 1 , further comprising placing the at least two sensors at predetermined locations in the coronary vessel that are proximate to branches in the vessel.

12. The method of claim 1 , wherein the characteristic is temperature, and wherein the method further comprises heating blood in the coronary vessel using a heating or cooling element on the lead and comparing the measured temperature at the at least two sensors.

13. The method of claim 7 , the method further comprising implanting the lead in the coronary sinus.

14. The device of claim 1 , wherein the at least two oximetry sensors are on a single lead.

15. The method of claim 7 , wherein the at least two oximetry sensors are on a single lead.