Implantable medical device charge balance assessment

1. A method for charge balance assessment in an implantable medical device, the method comprising:

delivering, via a current source, at least one electrical signal to tissue of a patient through an electrode; and

assessing, via a charge balance determination unit, whether a net charge remains on the electrode a predetermined period of time after the delivery of the electrical signal;

wherein said predetermined period of time is at least one hour.

2. The method of claim 1 , wherein assessing whether a net charge remains on the electrode comprises measuring a voltage differential between a charge balancing capacitor associated with the electrode and a reference voltage, and estimating the net charge remaining based on the measured voltage differential.

3. The method of claim 2 , wherein measuring the voltage differential comprises measuring a voltage differential across a resistor coupled to a charge balancing capacitor associated with the electrode and a reference voltage, and estimating the charge balance based on the measured voltage differential.

4. The method of claim 2 , wherein measuring the voltage differential between a charge balancing capacity and a reference voltage comprises measuring said differential from at least one of:

a) the proximal side of the charge balancing capacitor; and

b) the distal side of the charge balancing capacitor.

5. The method of claim 2 , wherein said reference voltage is selected from the group consisting of:

a) another electrode;

b) a common conductor of the implantable medical device; and

c) ground.

6. The method of claim 2 , wherein said reference voltage is selected from the group consisting of:

a) another electrode; and

b) a common conductor of the implantable medical device.

7. The method of claim 1 , further comprising generating a response based on the step of assessing whether a net charge imbalance remains on the electrode.

8. The method of claim 7 , wherein generating a response comprises at least one of:

a) generating a notification to one of the patient and a physician that a net charge remains on the electrode when the predetermined period of time has elapsed;

b) changing the electrical signal delivered by the electrode;

c) modifying a path by which the electrical signal is delivered such that an electrode other than the electrode carrying a net charge is used for delivering the electrical signal;

d) disabling delivery of the electrical signal by way of the electrode carrying a net charge;

e) switching from passive charge balancing to active charge balancing; and

f) increasing the active charge balancing to eliminate the net charge.

9. The method of claim 7 , wherein generating a response comprises at least one of:

a) generating a notification to one of the patient and a physician that a net charge remains on the electrode when the predetermined period of time has elapsed;

b) disabling delivery of the electrical signal by way of the electrode carrying a net charge; and

c) switching from passive charge balancing to active charge balancing.

10. The method of claim 1 , wherein delivering at least one electrical signal comprises delivering said at least one electrical signal via a plurality of electrodes, and the method further comprising assessing whether a net charge remains on each of said plurality of electrodes.

11. The method of claim 1 , further comprising selecting at least one electrode from among a plurality of electrodes through which to deliver the at least one electrical signal to tissue, and assessing whether a net charge remains on each said selected electrode.

12. The method of claim 1 , further comprising transmitting from the implantable medical device to an external programming device a signal indicative of whether a net charge remains on the electrode.