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Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed for automatic capture verification using cardiac activation sequence information. Devices and methods sense composite cardi

Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed for automatic capture verification using cardiac activation sequence information. Devices and methods sense composite cardiac signals using implantable electrodes. A source separation is performed using the composite signals. One or more signal vectors are produced that are associated with all or a portion of one or more cardiac activation sequences based on the source separation. A cardiac response to the pacing pulses is classified using characteristics associated with cardiac signal vectors and the signals associated with the vectors. Further embodiments may involve classifying the cardiac response as capture or non-capture, fusion or intrinsic cardiac activity. The characteristics may include an angle or an angle change of the cardiac signal vectors, such as a predetermined range of angles of the one or more cardiac signal vectors.

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What is claimed is: 1. A method of classifying a cardiac response to one or more pacing pulses, comprising: sensing one or more intrinsic composite cardiac signals, each intrinsic composite cardiac signal indicative of intrinsic cardiac activity and sensed using at least three spatially distributed

What is claimed is: 1. A method of classifying a cardiac response to one or more pacing pulses, comprising: sensing one or more intrinsic composite cardiac signals, each intrinsic composite cardiac signal indicative of intrinsic cardiac activity and sensed using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more intrinsic composite cardiac signals, the source separation separating one or more components of the intrinsic composite signal according to correlation between components of common cardiac origin; producing one or more intrinsic cardiac signal vectors representative of all or a portion of one or more intrinsic cardiac activation sequences based on the separated one or more components of the intrinsic composite cardiac signal; sensing one or more paced composite cardiac signals, each paced composite cardiac signal indicative of cardiac activity following delivery of pacing energy and sensed using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more paced composite cardiac signals, the source separation separating one or more components of the paced composite signal according to correlation between components of common cardiac origin; producing one or more paced cardiac signal vectors representative of all or a portion of one or more cardiac activation sequences based on the separated one or more components of the paced composite signal; establishing a vector orientation criterion based on respective orientations of the one or more intrinsic cardiac signal vectors and the one or more paced cardiac signal vectors; delivering a cardiac pacing pulse; sensing one or more composite cardiac signals following delivery of the cardiac pacing pulse using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more composite cardiac signals, the source separation separating one or more components of the composite cardiac signal according to correlation between components of common cardiac origin; producing one or more cardiac signal vectors representative of all or a portion of one or more cardiac activation sequences based on the separated one or more components of the composite cardiac signal; and classifying a cardiac response to the pacing pulse as capture or non-capture based on at least a comparison of orientation of the one or more cardiac signal vectors with the vector orientation criterion. 2. The method of claim 1, wherein establishing the vector orientation criterion further comprises determining an angular range between the one or more intrinsic cardiac signal vectors and the one or more paced cardiac signal vectors, and wherein classifying the cardiac response as capture or non-capture comprises determining whether the orientation of the one or more cardiac signal vectors is within the angular range. 3. The method of claim 1, wherein classifying the cardiac response further comprises classifying the cardiac response as fusion or intrinsic cardiac activity based on the vector orientation criterion and orientation of the one or more cardiac signal vectors. 4. The method of claim 1, wherein classifying the cardiac response to the pacing pulse as capture or non-capture further comprises comparing an angle or an angle change of the one or more cardiac signal vectors with the vector orientation criterion. 5. The method of claim 1, wherein the vector orientation criterion comprises a range of angles, and wherein classifying the cardiac response comprises determining if the vector falls within the range. 6. The method of claim 1, wherein classifying the cardiac response to the pacing pulse as capture or non-capture further comprises using a morphology of one or more signals associated with the one or more cardiac signal vectors to facilitate classifying of the cardiac response as capture or non-capture. 7. The method of claim 1, wherein the classification of the cardiac response to the pacing pulse as capture or non-capture further comprises use of a morphological change, relative to a baseline, of the one or more signals associated with the one or more cardiac signal vectors. 8. The method of claim 1, wherein classifying the cardiac response to the pacing pulse as at least one of capture or non-capture further comprises discriminating between left ventricular non-capture and right ventricular non-capture in response to delivery of bi-ventricular pacing pulses based at least on orientation of the one or more cardiac signal vectors. 9. The method of claim 1, comprising recommending increasing pacing pulse energy based on the classified cardiac response to the one or more pacing pulses as non-capture. 10. The method of claim 1, comprising triggering one or more threshold tests or increasing one or more pacing amplitudes in response to classifying the cardiac response as non-capture. 11. The method of claim 1, wherein classifying the cardiac response to the pacing pulse as at least one of capture or non-capture further comprises discriminating between one or more of capture, non-capture, fusion, and pseudofusion. 12. A cardiac system adapted to facilitate classification of a cardiac response to a pacing pulse, comprising: a plurality of implantable electrodes configured for sensing a composite signal, thereby providing a plurality of sensed composite cardiac signals; a housing configured for implantation in a patient; a controller configured to receive signals sensed by the implantable electrodes; memory; and a signal processor in communication with the memory, at least one of the controller and the signal processor configured to execute stored program instructions to cause the cardiac system to: perform a source separation for each composite cardiac signal of the plurality of sensed composite cardiac signals by separating one or more components of each composite cardiac signal of the plurality according to correlation between components of common cardiac origin, the plurality of composite cardiac signals comprising an intrinsic composite cardiac signal not associated with pacing energy delivery, a paced composite cardiac signal sensed following delivery of pacing energy, and a capture composite cardiac signal sensed following delivery of a pacing pulse, each source separation producing one or more cardiac signal vectors associated with all or a portion of a respective one of a plurality of cardiac activation sequences; establish a vector orientation criterion based on respective orientations of the cardiac signal vectors produced from the source separations of the intrinsic composite cardiac signal and the paced composite cardiac signal; compare orientation of the one or more cardiac signal vectors produced from the source separation of the capture composite cardiac signal with the vector orientation criterion; and classify the cardiac response to the pacing pulse as capture or non-capture using the comparison of the one or more cardiac signal vectors and the vector orientation criterion. 13. The system of claim 12, wherein the signal processor is provided in a patient-external device or system, the signal processor and the controller coupled to respective communication devices to facilitate wireless communication between the signal processor and the controller. 14. The system of claim 12, further comprising a lead configured for subcutaneous non-intrathoracic placement in a patient and coupled to the controller, wherein at least one of the plurality of implantable electrodes is supported by the lead. 15. The system of claim 12, wherein the signal processor is configured to execute stored program instruction to perform the source separations of the composite cardiac signals by using eigen values. 16. The system of claim 12, wherein one or both of the controller and the signal processor are configured to execute stored program instructions to cause the system to establish the vector orientation criterion as a vector orientation angular range based on an angle between respective orientations of the cardiac signal vectors produced from the source separation of the intrinsic composite signal and the raced composite signal, and classify the cardiac response to the pacing pulse as capture or non-capture by determining whether the orientation of the one or more cardiac signal vectors is within the vector orientation angular range. 17. The system of claim 12, wherein the signal processor is configured to execute stored program instruction to perform the source separations of the composite cardiac signals by implementing a blind source separation algorithm. 18. The system of claim 12, wherein the at least one of the controller and the signal processor is configured to execute stored program instructions to classify the cardiac response as capture, non-capture, fusion, or intrinsic cardiac activity. 19. The system of claim 12, wherein the cardiac system is configured to support one or more of atrial pacing, ventricular pacing, and bi-ventricular pacing and the signal processor is configured to execute store program instructions to cause the system to facilitate classification of the cardiac response to pacing pulses delivered in accordance with one or more of an atrial pacing therapy, a ventricular pacing therapy, and a bi-ventricular pacing therapy. 20. An implantable cardiac device, comprising: means for sensing a plurality of composite cardiac signals using a plurality of implantable cardiac electrodes; means for performing a respective source separation for each of a plurality of sensed composite cardiac signals by separating one or more components of each composite cardiac signal of the plurality according to correlation between components of common cardiac origin, the plurality of sensed composite cardiac signals comprising an intrinsic composite signal not associated with pacing energy delivery, a paced composite cardiac signal sensed following delivery of pacing energy, and a capture composite cardiac signal sensed following delivery of a pacing pulse, each source separation producing one or more cardiac signal vectors associated with all or a portion of a respective one of a plurality of cardiac activation sequences; means for establishing a vector orientation criterion based on respective orientations of the cardiac signal vectors produced from the source separation of the intrinsic composite signal and the paced composite signal; means for comparing orientation of the one or more cardiac signal vectors produced from the source separation of the capture composite signal with the vector orientation criterion; and means for classifying the cardiac response to the pacing pulse as capture or non-capture using the comparison of the one or more cardiac signal vectors and the vector orientation criterion the one or more cardiac signal vectors. 21. The device of claim 20, wherein the classifying means comprises means for detecting a change in the one or more cardiac signal vectors produced from the source separation of the capture composite signal relative to a baseline of the vector orientation criterion.