Abstract: An exemplary method includes accessing cardiac information acquired via a catheter located at various positions in a venous network of a heart of a patient wherein the cardiac information comprises position information with respect to time for one or more electrodes of the catheter; performing a principal component analysis on at least some of the position information; and selecting at least one component of the principal component analysis to represent an axis of a cardiac coordinate system. Various other methods, devices, systems, etc., are also disclosed.

Abstract: A system and method are provided for monitoring ischemic development. The system and method identify a non-physiologic event and obtain cardiac signals along multiple sensing vectors, wherein at least a portion of the sensing vectors extend to or from electrodes located proximate to the left ventricle. The system and method monitor a segment of interest in the cardiac signals obtained along the multiple sensing vectors to identify deviations in the segment of interest from a baseline. The system and method record at least one of timing or segment shift information associated with the deviations in the segments of interest; and identify at least one of size, direction of development or rate of progression of an ischemia region based on the at least one of timing or segment shift information.

Abstract: A method of synchronizing a heart rate with an activity rate of a patient includes determining the activity rate of the patient. The method also includes synchronizing a pacing pulse with a phase of the activity rate to improve a cardiac stroke volume of the patient. The synchronizing includes lowering the heart rate during down motion associated with the activity rate and increasing the heart rate during an up motion associated with the activity rate when a stride rate is slower than a target heart rate.

Abstract: An exemplary method includes selecting a first pair of electrodes to define a first vector and selecting a second pair of electrodes to define a second vector; acquiring position information during one or more cardiac cycles for the first and second pairs of electrodes wherein the acquiring comprises using each of the electrodes for measuring one or more electrical potentials in an electrical localization field established in the patient; and determining a dyssynchrony index by applying a cross-covariance technique to the position information for the first and the second vectors. Another method includes determining a phase shift based on the acquired position information for the first and the second vectors; and determining an interventricular delay based at least in part on the phase shift.

Abstract: A method is provided to determine pacing parameters for an implantable medical device (IMD) and collects heart sounds during the cardiac cycles. The method comprises changing a value for a pacing parameter between the cardiac cycles and analyzing a characteristic of interest from the heart sounds. The method comprises setting a desired value for the pacing parameter based on the characteristic of interest from the heart sounds. The system comprises inputs configured to be coupled to at least one lead having electrodes to sense intrinsic events and to deliver pacing pulses over cardiac cycles. The system has a sensor for collecting heart sounds during cardiac cycles and controller to control delivery of pacing pulses based on pacing parameters. The controller changes a value for at least one of the pacing parameters between the cardiac cycles and provides an analysis module to analyze a characteristic of interest from the heart sounds.

Abstract: Techniques are provided for use with an implantable medical device for detecting and assessing heart failure and for controlling cardiac resynchronization therapy (CRT) based on impedance signals obtained using hybrid impedance configurations. The hybrid configurations exploit right atrial (RA)-based impedance measurement vectors and/or left ventricular (LV)-based impedance measurement vectors. In one example, current is injected between the device case and a ring electrode in the right ventricle (RV) or RA. RA-based impedance values are measured along vectors between the device case and an RA electrode. LV-based impedance values are measured along vectors between the device case and one or more electrodes of the LV. Heart failure and other cardiac conditions are detected and tracked using the measured impedance values. CRT delay parameters are also optimized based impedance.

Abstract: Techniques are provided for use with implantable medical devices equipped to deliver paired postextrasystolic potentiation (PESP) pacing to control the paired pacing rate based on changes in patient activity. In one example, the current activity level of the patient is detected during paired pacing using an accelerometer. The cardiac output level needed to maintain the current activity level of the patient is determined with reference to pre-stored lookup tables relating activity levels with corresponding minimum necessary cardiac output levels for the particular patient. The minimum paired pacing rate sufficient to achieve the cardiac output level is then determined based, e.g., on stroke volume derived from cardiogenic impedance signals. Paired pacing is then delivered at the minimum paired pacing rate sufficient to achieve the needed cardiac output, thereby assuring that the paired pacing rate is sufficient to meet the current physiological demands of the patient without consuming too much oxygen.

Abstract: A signal indicative of left atrial pressure in the heart of a patient is analyzed to identify a signal component that is related to the respiration of the patient. An indication relating to the left atrial pressure may be generated based on the presence, absence, or magnitude of the respiratory component. In some embodiments the indication may be used to indicate high left atrial pressure. In some embodiments the indication may be used to indicate heart failure. In some embodiments the indication may be used in conjunction with verifying the operation of a left atrial pressure sensor. In the event of high left atrial pressure or an incorrect pressure reading an appropriate warning may be generated. In the event of an incorrect pressure reading the left atrial pressure sensor may be recalibrated.

Abstract: Diastolic function is monitored within a patient using a pacemaker or other implantable medical device. In one example, the implantable device uses morphological parameters derived from the T-wave evoked response waveform as proxies for ventricular relaxation rate and ventricular compliance. In particular, the magnitude of the peak of the T-wave evoked response is employed as a proxy for ventricular compliance. The maximum slew rate of the T-wave evoked response following its peak is employed as a proxy for ventricular relaxation. A metric is derived from these proxy values to represent diastolic function. The metric is tracked over time to evaluate changes in diastolic function. In other examples, specific values for ventricular compliance and ventricular relaxation are derived for the patient based on the T-wave evoked response parameters.

Abstract: Methods for monitoring a patient's level of B-type natriuretic peptide (BNP), and implantable cardiac systems capable of performing such methods, are provided. A ventricle is paced for a period of time to provoke a ventricular evoked response, and a ventricular intracardiac electrogram (IEGM) indicative of the ventricular evoked response is obtained. Based on the ventricular IEGM, there is a determination of at least one ventricular evoked response metric (e.g., ventricular evoked response peak-to-peak amplitude, ventricular evoked response area and/or ventricular evoked response maximum slope), and the patient's level of BNP is monitored based on determined ventricular evoked response metric(s). Based on the monitored level's of BNP, the patients heart failure (HF) condition and/or risks and/or occurrences of certain events (e.g., an acute HF exacerbation and/or an acute myocardial infarction) can be monitored.

Abstract: An exemplary method includes accessing cardiac information acquired via a catheter located at various positions in a venous network of a heart of a patient where the cardiac information comprises position information, electrical information and mechanical information; mapping local electrical activation times to anatomic positions to generate an electrical activation time map; mapping local mechanical activation times to anatomic positions to generate a mechanical activation time map; generating an electromechanical delay map by subtracting local electrical activation times from corresponding local mechanical activation times; and rendering at least the electromechanical delay map to a display. Various other methods, devices, systems, etc., are also disclosed.

Abstract: A method of identifying a potential cause of pulmonary edema is provided. The method includes obtaining one or more impedance vectors between predetermined combinations of the electrodes positioned proximate the heart. At least one of the impedance vectors is representative of a thoracic fluid level. The method also includes applying a stimulation pulse to the heart and sensing cardiac signals of the heart that are representative of an electrophysiological response to the stimulation pulse. The method further includes monitoring the cardiac signals and at least one of the impedance vectors with respect to time to identify the potential cause of pulmonary edema.

Abstract: An exemplary method generates a map of a pacing parameter, a sensing parameter or one or more other parameters based in part on location information acquired using a localization system configured to locate electrodes in vivo (i.e., within a patient's body). Various examples map capture thresholds, qualification criteria for algorithms, undesirable conditions and sensing capabilities. Various other methods, devices, systems, etc., are also disclosed.

Abstract: Techniques are provided for use by a pacemaker or other implantable medical device for detecting and tracking trends in cardiopulmonary fluid transfer rates—such as heart-to-lung fluid perfusion rates and lung-to-lymphatic system fluid excretion rates—and for detecting heart failure, dyspnea or other cardiopulmonary conditions. In one example, the device periodically measures transthoracic admittance values. A first exponential time-constant (k1) is determined using curve-fitting from admittance values obtained while the patient is in a sleep posture. Time-constant k1 is representative of the fluid perfusion rate. A second exponential time-constant (k2) is determined based on admittance values obtained while the patient is standing/walking/sitting. The second exponential time-constant (k2) is representative of the fluid excretion rate from the lungs.

Abstract: Disclosed herein is a method of optimizing the implantation of an implantable medical lead into a patient to optimize electrotherapy administered via the lead. The method includes: inserting the lead into the patient, the lead including a first electrode; providing a second electrode in the patient, wherein the second electrode is not part of the lead; generating an electrical vector between the first electrode and second electrode, the electrical vector being generated as the lead is being implanted; analyzing the electrical vector as the lead is being implanted; and optimizing the implantation of the lead based off of the analysis of the electrical vector to optimize electrotherapy administered via the lead.

Abstract: Diastolic function is monitored within a patient using a pacemaker or other implantable medical device. In one example, the implantable device uses morphological parameters derived from the T-wave evoked response waveform as proxies for ventricular relaxation rate and ventricular compliance. In particular, the magnitude of the peak of the T-wave evoked response is employed as a proxy for ventricular compliance. The maximum slew rate of the T-wave evoked response following its peak is employed as a proxy for ventricular relaxation. A metric is derived from these proxy values to represent diastolic function. The metric is tracked over time to evaluate changes in diastolic function. In other examples, specific values for ventricular compliance and ventricular relaxation are derived for the patient based on the T-wave evoked response parameters.

Abstract: An implantable medical device (“IMD”) processes and analyzes valuable clinical information regarding cardiac performance. A database or correlator is pre-customized to the specific patient, by correlating signals received by a remote accelerometer associated with heart movements with accurate heart sounds recorded from a microphone to provide a more effective and customized basis for estimating heart sound. The information is then used to better control an implantable medical device.

Abstract: Selection of an appropriate rate programming control (RPC) setting in an implantable medical device (IMD), uses analysis of VA coupling surrogate conditions. The VA coupling surrogate conditions are derived from signals such as cardiogenic impedance, blood pressure, and the pulsatile components of PPG. By analyzing a waveform of the measured surrogate condition, the IMD estimates wall stiffness, through the slope of the waveform, and peripheral arterial pressure, through the reflection time between the main wave and reflection wave of the waveform. These values are plotted against each other on a VA coupling coordinate plane. Based on the location and orientation of the resulting VA coupling plot, the IMD selects an appropriate RPC setting.

Abstract: Techniques are provided for detecting a clinically-significant pulmonary fluid accumulation within a patient using a pacemaker or other implantable medical device. Briefly, the device detects left atrial pressure (LAP) within the patient and tracks changes in the LAP values over time that are indicative of possible pulmonary fluid accumulation within the patient. The device determines whether the changes in LAP values are sufficiently elevated and prolonged to warrant clinical intervention using, e.g., a predictor model-based technique. If the fluid accumulation is clinically significant, the device then generates warning signals, records diagnostics, controls therapy and/or titrates diuretics. False positive detections of pulmonary edema due to transients in LAP are avoided with this technique. Pulmonary artery pressure (PAP)-based techniques are also described.

Abstract: A system and method for treating an arrhythmia in a heart are provided. The system includes an electronic control unit configured to monitor movement of one or more position sensor over a period of time. The position sensors may, for example, comprise electrodes or coils configured to generate induced voltages and currents in the presence of electromagnetic fields. The positions sensors are in contact with portions of heart tissue and changes in position are representative of motion of that tissue. The electronic control unit is further configured to generate an indicator, responsive to the movements of the sensors over the period of time, of a characteristic of the heart affected by delivery of ablation energy to heart tissue. In this manner, the effectiveness and safety of cardiac tissue ablation for treatment of the arrhythmia can be assessed and a post-ablation therapy regimen determined.