US Patent 7499751 Cardiac signal template generation using waveform clustering

Cardiac devices and methods using cardiac waveform clustering for template generation are described. A method of characterizing a cardiac response involves delivering pacing pulses to heart, the pulses having an energy greater than a capture threshold. Cardiac signals are sensed following the pulses. Cardiac signal characteristics, waveforms, and/or features are clustered into a plurality of clusters. A cardiac response template is formed using one or more of the plurality of clusters.