Ventricular pacing

1. An implantable medical device comprising:

a signal generator configured to:

provide a first electrostimulation energy to a first electrode disposed in a right ventricle of a heart, the first electrostimulation energy having a first potential relative to a reference potential at a first reference electrode; and

provide a second electrostimulation energy to a second electrode disposed in the right ventricle of the heart, the second electrostimulation energy having a second potential relative to the reference potential at the reference electrode;

wherein the first and second electrostimulation energies comprise at least partially overlapping, opposite polarity electrostimulation energies with respect to the reference potential; and

wherein one of the first and second electrodes is configured to be secured to a target location near a bundle of His.

2. The implantable medical device of claim 1 , comprising the first electrode the second electrode, and the first reference electrode.

3. The implantable medical device of claim 2 , wherein the signal generator is configured to be coupled to at least one of the first and second electrodes being disposed in the right ventricle and being secured to the septum of the heart.

4. The implantable medical device of claim 2 , wherein the signal generator is configured to be coupled to at least one of the first and second electrodes being disposed in the right ventricle and being secured near the tricuspid valve of the right ventricle.

5. The implantable medical device of claim 2 , wherein the signal generator is configured to be coupled to the first reference electrode being disposed remote from the heart.

6. The implantable medical device of claim 2 , wherein the signal generator is configured to be coupled to the first reference electrode disposed on a housing of the implantable medical device.

7. The implantable medical device of claim 2 , wherein the signal generator is configured to be coupled to a first reference electrode being disposed in one of a left ventricle, a tissue of the free wall of the left ventricle, on the epicardial surface of the left ventricle, or in a coronary sinus.

8. The implantable medical device of claim 2 , comprising a second reference electrode and a switch configured to select one of the first and second reference electrodes.

9. The implantable medical device of claim 1 , comprising an electrode configured to be disposed in an atrium of the heart to facilitate atrial-ventricular sequential pacing.

10. The implantable medical device of claim 1 , comprising a defibrillation lead system with at least one shock electrode and circuitry configured for energizing the defibrillation lead system for defibrillation therapy.

11. The implantable medical device of claim 1 , wherein the signal generator is configured to provide the first and second electrostimulation energies to a selected area near or at the septum of the heart for treating a bundle branch block.

12. The implantable medical device of claim 1 , wherein the one of the first and second electrodes is sized and shaped to be secured to the septum of the heart at the bundle of His, and wherein the other one of the first and second electrodes is sized and shaped to be secured at or near an apex of the right ventricle of the heart.

13. A method for providing a therapy to treat a bundle branch block of a heart, the method comprising:

generating a pacing signal that includes first and second signal components having opposite polarity and at least partially overlapping in time, wherein the first and second signal components have a potential relative to at least one of multiple reference electrodes placed subcutaneously in or near the heart;

applying the pacing signal to the heart using first and second electrodes in or near a right ventricle of the heart and at least one of the multiple refrence electrodes; and

identifying a patient physiological response to the applied pacing signal;

wherein identifying the patient physiological response includes identifying a ventricular contraction of the heart in the presence of a bundle branch block.

14. The method of claim 13 , wherein applying the pacing signal to the heart comprises:

applying a first pacing signal to the heart using a first one of the multiple reference electrodes; and

applying a second pacing signal o the heart using a different second one of the multiple reference electrodes;

wherein identifying the patient physiological response to the applied pacing signal comprises identifying a patient physiological response that corresponds to each of the first and second pacing signals.

15. The method of claim 13 , wherein applying the pacing signal to the heart using the first and second electrodes comprises applying the pacing signal to a target location near a bundle of His using one of the first and second electrodes secured to the target location.

16. The method of claim 13 , wherein applying the pacing signal includes applying a pacing signal that includes a biphasic component and has a magnitude of less than about 20 volts.

17. The method of claim 13 , wherein applying the pacing signal comprises using at least one of the first and second electrodes near the tricuspid valve.

18. The method of claim 13 , comprising using a refrence electrode more proximate to a signal generator than the heart, wherein the signal generator is configured to generate the pacing signal.

19. The method of claim 13 , wherein generating the pacing signal that includes first and second signal components includes generating a pacing signal that includes first and second signal components that have different signal magnitudes.

20. An implantable medical device configured to treat a bundle branch block, the implantable medical device comprising:

a signal generator configured to:

provide a first electrostimulation energy to a first electrode that is configured to be secured to a heart wall near a bundle of His of the heart and near the tricuspid valve of the heart, the first electrostimulation energy having a first potential relative to a reference potential at a reference electrode; and

provide a second electrostimulation energy to a second electrode disposed in or near the right ventricle of the heart, the second electrostimulation energy having a second potential relative to the reference potential at the reference electrode;

wherein the first and second electrostimulation energies comprise at least partially overlapping, opposite polarity electrostimulation energies with respect to the reference potential, and wherein one of the first and second electrostimulation energies comprises a biphasic signal component.