An apparatus for coupling to a plurality of electrodes implantable at a plurality of tissue sites of a heart chamber of a subject. The apparatus including a stimulus circuit configured to provide an electrical cardiac pacing stimulation to the plurality of electrodes, a switching circuit configured to select electrodes of the plurality of electrodes for electrical coupling to the stimulus circuit, and a control circuit including a heart rate sub-circuit configured to determine heart rate; and a pacing site activation sub-circuit configured to selectively change which electrodes of the plurality of electrodes are used to provide the electrical cardiac pacing stimulation therapy according to the determined heart rate.

A method for determining the degree of parallel activation of a heart undergoing pacing includes calculating vectorcardiogram (VCG), or electrocardiogram (ECG), or electrogram (EGM) waveforms from right ventricular pacing (RVp) and left ventricular pacing (LVp). A synthetic biventricular pacing (BIVP) waveform is generated by summing the VCG of the RVp and LVp, or by summing the ECG of the RVp and the LVp, or by summing the EGM of the RVp and the LVp. A corresponding EGM or ECG or VCG waveform from real BIVP is calculated. The method includes comparing the synthetic BIVP waveform and the real BIVP waveform and calculating time to fusion by determining the point in time in which the activation from RVp and LVp meets and the synthetic and the real BIVP curves start to deviate. A delay in time to fusion indicates a higher degree of parallel activation.

Methods, apparatus, and systems are provided to control contraction of the heart. At least one sensing element receives signals indicating electrical activity of sinus rhythm of the heart. Based on the received signals, the progress of contraction of the heart is determined. Based on the progress of contraction, the chamber of the heart may then be stimulated at a plurality of locations. In another embodiment, a plurality of electrodes are implanted in the left ventricle to stimulate at multiple locations in the left ventricle for the purpose of improving hemodynamic performance and increasing cardiac output in a patient who is suffering from congestive heart failure.

Methods and devices are provided for, under control of one or more processors within an implantable medical device (IMD), delivering cardiac resynchronization therapy (CRT) at one or more pacing sites. The processors obtain cardiac signals, associated with a candidate beat, from multi-site left ventricular (MSLV) electrodes distributed along a left ventricle and analyze the cardiac signals to collect at least one of a MSLV conduction pattern or a MSLV morphology. The processors compare at least one of the MSLV conduction pattern or MSLV morphology to one or more associated templates. The processors then label the candidate beat as a pseudo-fusion beat based on the comparing and adjust the CRT based on the labeling.

Systems and methods for dynamically controlling HBP delivery based on patient AV conduction status are disclosed. An exemplary medical system includes an electrostimulation circuit to generate HBP pulses to stimulate a His bundle or a bundle branch of the heart. An AV conduction monitor circuit continuously or periodically assesses AV conduction status, and detects an indication of presence or absence of AV conduction abnormality. If an AV conduction abnormality is indicated, a control circuit may control the electrostimulation circuit to deliver the HBP pulses. Ventricular backup pacing may be delivered if HBP fails to capture and elicit ventricular activation. When the AV conduction become normal, the control circuit may withhold HBP delivery and promote patient intrinsic ventricular activation.

According to some embodiments, a device operates by comparative morphological analysis of depolarization signals collected in spontaneous rhythm on separate respective channels, with two temporal components combined into a single 2D parametric VGM vectogram characteristic. Similarity quantification methods evaluate a variation over time of a descriptor parameter of a current VGM compared to a stored previous reference VGM. This variation is compared with predetermined thresholds to diagnose an occurrence of remodeling or reverse remodeling in a patient, and/or to detect a lead failure or an occurrence of ischemia. The descriptor parameter is a function of a velocity vector of the VGM, a comparison relating to a correlation coefficient between respective magnitudes of a current VGM velocity vector and of a reference VGM velocity vector, and an average angle between these respective velocity vectors.

A system is provided for controlling a left univentricular (LUV) pacing therapy using an implantable medical device (IMD). The system also includes one or more processors configured to determine an atrial-ventricular (AV) conduction interval (AR.sub.RV) between the A site and a first RV sensed event at the RV site, determine an inter-ventricular (VV) conduction interval (R.sub.LV-R.sub.RV) between a paced event at the LV site and a second RV sensed event at the RV site, and set a ventricular refractory period (VRP) based on at least one of the AV conduction interval or the VV conduction interval and a predetermined offset. The one or more processors are also configured to blank signals over the RV sensing channel during the VRP.

Computer implemented methods, devices and systems for monitoring a trend in heart failure (HF) progression are provided. The method comprises sensing left ventricular (LV) activation events at multiple LV sensing sites along a multi-electrode LV lead. The activation events are generated in response to an intrinsic or paced ventricular event. The method implements program instructions on one or more processors for automatically determining a conduction pattern (CP) across the LV sensing sites based on the LV activation events, identifying morphologies (MP) for cardiac signals associated with the LV activation events and repeating the sensing, determining and identifying operations, at select intervals, to build a CP collection and an MP collection. The method calculates an HF trend based on the CP collection and MP collection and classifies a patient condition based on the HF trend to form an HF assessment.

An implantable device comprises a plurality of electrode pairs, a sensing unit, and a pacing unit. The electrode pairs comprise a first electrode pair. The first electrode pair is configured to implant at or near a first location of a heart. The sensing unit is configured to sense electrical activity in the heart, determine that the electrical activity indicates an abnormal rhythm, determine a feature of the electrical activity, and select the first electrode pair from the electrode pairs based on the feature. The pacing unit is configured to cause, in response to the abnormal rhythm and the feature, the first electrode pair to provide a first electrical pulse at a first time.

The embodiments described herein relate to a self-positioning, quick-deployment low profile transvenous electrode system for sequentially pacing both the atrium and ventricle of the heart in the “dual chamber” mode, and methods for deploying the same.