Patent ID: 8229556

Claim:
A method, comprising: sensing, within a patient using implantable electrodes, an electrical signal indicative of electrical activity of the patient's heart; identifying a tachycardia event based on the electrical signal; sensing, within the patient and during the tachycardia event, a mechanical response signal indicative of a mechanical response of the patient's heart to the tachycardia; developing a template indicative of the mechanical response of the patient's heart to tachycardia based on the mechanical response signal; sensing a second mechanical response signal indicative of the mechanical response of the patient's heart to a subsequent tachycardia event; determining regularity of the second mechanical response signal relative to a threshold established for the patient by comparing the template to the second mechanical response signal; determining a state of patient hemodynamics during the subsequent tachycardia event based at least in part on the regularity of the second mechanical response signal, wherein determining the state comprises determining whether the subsequent tachycardia event comprises a stable tachyarrhythmia or unstable tachyarrhythmia; selecting one or more therapies to treat the subsequent tachycardia event based at least in part on the determined state of patient hemodynamics; and delivering the selected one or more therapies to treat the subsequent tachycardia event, wherein the steps of developing the template, determining the regularity, determining the state of hemodynamics, selecting, and delivering are performed at least in part by circuitry.