Method and apparatus for monitoring left ventricular work or power
A body implantable system employs a lead system having at least one electrode and at least one thermal sensor at a distal end. The lead system is implanted within a patient's heart in a coronary vein of the left ventricle. The thermal sensor can be attached to a catheter that is disposed within an open lumen of the lead system. The thermal sensor senses a coronary vein temperature. The coronary vein temperature can be measured at a detector/energy delivery system and used as an activity indicator to adaptively control pacing rate. The measured coronary vein temperature can be also used with a left ventricular flow measurement to determine hemodynamic efficiency of the heart. A detected change in hemodynamic efficiency can be used by the detector/energy delivery system to modify the delivery of electrical pulses to the lead system.
1. A body implantable system, comprising:
a lead system comprising an elongated body, an open lumen, and at least one electrode at a distal end of the lead system;
a sensing catheter movably disposed within the open lumen of the lead system, a distal tip of the sensing catheter extending beyond a distal tip of the lead system, the sensing catheter comprising at least one thermal sensor at a distal end of the sensing catheter; and
a detector/energy delivery system coupled to the lead system, the detector/energy delivery system sensing ventricular rhythms from the at least one electrode and sensing blood temperature from the at least one thermal sensor, the detector/energy delivery system delivering an electrical signal to the at least one electrode.
2. The system of claim 1 , wherein the thermal sensor comprises a thermistor.
3. The system of claim 1 , wherein the thermal sensor comprises a MEMS temperature sensor.
4. The system of claim 1 , wherein the thermal sensor comprises a thermocouple.
5. The system of claim 1 , wherein the thermal sensor comprises a fiber optic temperature probe.
6. The system of claim 1 , wherein the detector/energy delivery system modifies the delivery of electrical signals based on the sensed blood temperature.
7. The system of claim 1 , further comprising a flow sensor for sensing a cardiac output, and wherein the detector/energy delivery system further senses a left ventricular flow rate from the flow sensor.
8. The system of claim 7 , wherein the flow sensor comprises a ventricular impedance sensor.
9. The system of claim 7 , wherein the detector/energy delivery system determines a hemodynamic efficiency of the heart using the sensed left ventricular flow rate and the sensed blood temperature.
10. The system of claim 7 , wherein the detector/energy delivery system modifies the delivery of electrical signals based on the sensed left ventricular flow rate and the sensed blood temperature.
11. The system of claim 1 , further comprising a ventricular thermal sensor for sensing a blood temperature entering the left ventricle, the ventricular thermal sensor coupled to the detector/energy delivery system, and wherein the detector/energy delivery system further senses a temperature difference between the ventricular thermal sensor and the at least one thermal sensor at a distal end of the sensing catheter.
12. The system of claim 11 , wherein the detector/energy delivery system determines a hemodynamic efficiency of the heart using the sensed temperature difference.
13. The system of claim 11 , wherein the detector/energy delivery system modifies the delivery of electrical signals based on the sensed temperature difference.
14. The system of claim 1 , further comprising an activity sensor coupled to the detector/energy delivery system.
15. The system of claim 14 , wherein the activity sensor comprises an accelerometer.
16. The system of claim 14 , wherein the activity sensor comprises a minute ventilation sensor.
17. The system of claim 14 , wherein the detector/energy delivery system updates a long term average blood temperature measurement from the at least one thermal sensor, the long term average blood temperature updated at a state of rest as sensed by the activity sensor.