Abstract: Techniques are presented for providing adjustable cardiac resynchronization with an implanted medical device such as a pacemaker. For example, cardiac resynchronization may be provided during some time periods but not during other time periods, or cardiac resynchronization may be provided in response to selected sensed events. Adjustable cardiac resynchronization is applicable to therapy such as bi-ventricular pacing, in which both ventricles of the heart are paced in response to sensed atrial events.

Abstract: A method and apparatus for deriving trend data indicative of the state of heart failure in a cardiac pacing system capable of delivering electrical stimulus to first and second ventricular sites that includes a timing circuit to begin measuring a time interval from a first ventricular event occurring at a selected one of the first and second ventricular sites, a sensing circuit coupled to the timing circuit to detect a second ventricular depolarization in the other of the first and second ventricular sites, and a storage device coupled to the timing circuit to store one or more elapsed conduction times that may be utilized as an indicator of the state of heart failure.

Abstract: Techniques are presented for providing adjustable cardiac resynchronization with an implanted medical device such as a pacemaker. For example, cardiac resynchronization may be provided during some time periods but not during other time periods, or cardiac resynchronization may be provided in response to selected sensed events. Adjustable cardiac resynchronization is applicable to therapy such as bi-ventricular pacing, in which both ventricles of the heart are paced in response to sensed atrial events.

Abstract: Multi-site cardiac pacing systems that pace and sense in at least a first site in the heart and sense conducted electrical signals at a second site in the heart and measure and accumulate electrical conduction times between the first and second sites to derive trend data indicative of the state of heart failure. Preferably the sites are right heart chamber and left heart chamber sites, e.g., right and left atrial sites or right and left ventricular sites. In a ventricular embodiment, a V-V conduction time is measured from a ventricular sense (VS) event or a ventricular pace (VP) pulse delivered to a selected one of first and second ventricular sites to the VS event at the other one of the first and second ventricular sites. The measured V-V conduction time can be one or more of a VS-VS conduction time, a VP-VS conduction time and a VS/VP-VS conduction time.