Abstract: An exemplary method includes providing information (e.g., a left atrial pressure, a NYHA class, echocardiographic information, etc.), based at least in part on the information, determining a weight and, based at least in part on the weight, determining a threshold for use in intrathoracic impedance monitoring. Such an exemplary method may include comparing an intrathoracic impedance to the threshold, comparing an intrathoracic impedance change to the threshold, or comparing a product of intrathoracic impedance and time to the threshold. Various exemplary methods, devices, systems, etc., are disclosed.

Abstract: A first cardiac signal associated with an activity of a first implant site of a heart during a cardiac cycle is sensed. A second cardiac signal is sensed using an intrapericardial lead located on an epicardial surface proximate a second implant site of the heart. The second cardiac signal is associated with an activity of the second implant site during the cardiac cycle. A timing delay between the activity of the first implant site and the activity of the second implant site is obtained and analyzed to determine if the intrapericardial lead location is appropriate. The preceding is repeated until an appropriate intrapericardial lead location is determined. Other measurements obtained during implant determine whether the intrapericardial lead location is at or near slow conduction zone and whether the intrapericardial lead is placed at the location having the greatest mechanical delay. Post implant measurements determine whether the intrapericardial lead has migrated.

Abstract: Techniques are provided for configuring filters for reducing heating within pacing/sensing leads of a pacemaker or implantable cardioverter-defibrillator that might occur due to induced currents during a magnetic resonance imaging (MRI) procedure or in the presence of other sources of strong radio frequency (RF) fields. In particular, techniques are provided for selecting inductors and capacitors for use in LC filters while taking into account the tolerances of the component devices, as well as the target impedance of the components and the particular RF frequencies to be filtered.

Abstract: A leadless intra-cardiac medical device (LIMD) configured to be implanted entirely within a heart of a patient includes a housing configured to be securely attached to an interior wall portion of a chamber of the heart, and a stabilizing intra-cardiac (IC) device extension connected to the housing. The stabilizing IC device extension may include a stabilizer arm, and/or an appendage arm, or an elongated body or a loop member configured to be passively secured within the heart.

Abstract: A leadless intra-cardiac medical device includes a housing that is configured to be implanted entirely within a single local chamber of the heart. A first electrode is provided on the housing at a first position such that when the housing is implanted in the local chamber, the first electrode engages the local wall tissue at a local activation site within the conduction network of the local chamber. An intra-cardiac extension is coupled to the housing and configured to extend from the local chamber into an adjacent chamber of the heart. A stabilization arm of the intra-cardiac extension engages the adjacent chamber. A second electrode on the intra-cardiac extension engages distal wall tissue at a distal activation site within the conduction network of the adjacent chamber.

Abstract: Techniques are provided for corroborating a preliminary detection of pulmonary fluid overload within a patient made initially based on transthoracic impedance. In one example, corroborative parameters pertaining to hematocrit, device pocket fluid accumulations, heart rate variability (HRV) and mean atrial tachycardia/atrial fibrillation (AT/AF) times are evaluated to confirm the fluid overload. Techniques are also provided for generating proxies for evaluating hematocrit and device pocket fluid accumulation based on certain impedance measurements. Still further, techniques are provided for predicting a possible pulmonary fluid overload based on trends in HRV or mean AT/AF times. System and method examples are set forth herein.

Abstract: A leadless intra-cardiac medical device is configured to be implanted entirely within a heart of a patient. The device includes an intra-cardiac extension and a housing. The intra-cardiac extension includes a loop body having at least one loop segment retaining at least one coil group that is configured to one or both of receive and transmit radio frequency (RF) energy, wherein the loop body is configured to extend into a first chamber of the heart. The housing is in electrical communication within the loop body, and includes a transceiver, control logic and an energy source. The housing is configured to be securely attached to an interior wall portion of a second chamber of the heart, wherein the transceiver is configured to communicate with an external device through the RF energy.

Abstract: A leadless intra-cardiac medical device (LIMD) includes an electrode assembly configured to be anchored within a first wall portion of a first chamber of a heart. The electrode assembly includes an electrode main body having a first securing helix, an electrode wire segment extending from the body, and a first segment-terminating contact positioned on the electrode wire segment. The device further includes a housing assembly configured to be anchored within a second wall portion of a second chamber of the heart. The housing assembly includes a body having a second securing helix, a housing wire segment extending from the body, and a second segment-terminating contact positioned on the housing wire segment. The device also includes a connector block that electrically connects the electrode wire segment to the housing wire segment by retaining the first and second segment-terminating contacts.

Abstract: A filter circuit embedded into a header of an implantable medical device attenuates energy that may otherwise enter the implantable medical device. At MRI frequencies, the impedance of the filter circuit is much higher than the impedance of the feedthrough capacitor of the implantable medical device. Thus, MRI-induced current that would otherwise enter the implantable medical device is limited by the filter circuit. Consequently, localized device heating that may otherwise occur during MRI scanning is significantly reduced by operation of the filter circuit. In some implementations, the header embedded filter circuit is electrically isolated from the header housing. In this way, localized heating of the header housing also may be avoided.

Abstract: An intra-pericardial medical device is provided that comprises a lead body having a proximal portion, a distal end portion, and an intermediate portion extending between the proximal portion and the distal end portions. An intra-pericardial medical device further includes the control logic housed with the lead body and an energy source housed within the lead body. A stimulus conductor is included and extends along the lead body. An electrode is joined to the stimulus conduct near the distal end portion, where the electrode configured to deliver stimulus pulses. A telemetry conductor is provided within the lead and extends from the proximal portion and along the intermediate portion of the lead body. The telemetry conductor is wound into a series of coil groups to form inductive loops for at least one of receiving and transmitting radio frequency (RF) energy.

Abstract: Techniques are provided for use by implantable medical devices for controlling ventricular pacing, particularly during atrial fibrillation. In one example, during a V sense test for use in optimizing ventricular pacing, the implantable device determines relative degrees of variation within antecedent and succedent intervals detected between ventricular events sensed on left ventricular (LV) and right ventricular (RV) sensing channels. Preferred or optimal ventricular pacing delays are then determined, in part, based on a comparison of the relative degrees of variation obtained during the V sense test. In another example, during RV and LV pace tests, the device distinguishes QRS complexes arising due to interventricular conduction from QRS complexes arising due to atrioventricular conduction from the atria, so as to permit the determination of correct paced interventricular conduction delays for the patient. The paced interventricular conduction delays are also used to optimize ventricular pacing.

Abstract: To provide radio-frequency (RF) bandstop filtering within an implantable lead for use in reducing lead heating during magnetic resonance imaging (MRI) procedures, parallel inductive-capacitive (LC) filters are provided within the lead. In one example, the ring electrode of the lead is configured to function as one of the capacitive elements of the parallel LC filter to help provide LC bandstop filtering along the ring conductor of the lead. In another example, capacitive plates are provided that sandwich an inductor mounted near the tip of the lead to provide parallel LC bandstop filtering along the tip conductor of the lead.

Abstract: An exemplary method includes delivering a cardiac pacing therapy that includes an atrio-ventricular delay and an interventricular delay, providing a paced propagation delay associated with delivery of a stimulus to a ventricle, delivering a stimulus to the ventricle, sensing an event in the other ventricle caused by the stimulus, determining an interventricular conduction delay value based on the delivering and the sensing, determining a interventricular delay (?Sur) based on the interventricular conduction delay and the paced propagation delay and determining an atrio-ventricular delay based at least in part on the interventricular delay (?Sur). Other exemplary methods, devices, systems, etc., are also disclosed.

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 by implantable medical devices for controlling ventricular pacing, particularly during atrial fibrillation. In one example, during a V sense test for use in optimizing ventricular pacing, the implantable device determines relative degrees of variation within antecedent and succedent intervals detected between ventricular events sensed on left ventricular (LV) and right ventricular (RV) sensing channels. Preferred or optimal ventricular pacing delays are then determined, in part, based on a comparison of the relative degrees of variation obtained during the V sense test. In another example, during RV and LV pace tests, the device distinguishes QRS complexes arising due to interventricular conduction from QRS complexes arising due to atrioventricular conduction from the atria, so as to permit the determination of correct paced interventricular conduction delays for the patient. The paced interventricular conduction delays are also used to optimize ventricular pacing.

Abstract: A method is disclosed that includes selecting an electrode configuration from a plurality of electrode configurations associated with electrodes of an implantable lead, sensing activity of the right ventricle and the left ventricle, determining an interval between sensed activity of the right ventricle and sensed activity of the left ventricle and determining whether the selected electrode configuration is suitable based at least in part on the interval. In one embodiment, an implantable device performs such a method to improve patient response to the CRT therapy, for example, by selecting a different electrode configuration if the current configuration is not suitable. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: Systems and methods are provided for reducing heating within pacing/sensing leads of a pacemaker or implantable cardioverter-defibrillator that occurs due to induced radio frequency (RF) currents during a magnetic resonance imaging (MRI) procedure, or in the presence of other sources of strong RF fields. For example, bipolar coaxial leads are described wherein the ring conductor of the lead is disconnected from the ring electrode via a switch in response to detection of MRI fields to convert the ring conductor into an RF shield for shielding the inner tip conductor of the lead so as to reduce the strength of RF currents induced therein and hence reduce tip heating. Other exemplary leads are described wherein a band stop filter is instead used to block RF signals to likewise convert the ring conductor into an RF shield. The switches and band stop filters also help to prevent MRI-induced stimulation.

Abstract: Exemplary techniques and systems for interpolating left ventricular pressures are described. One technique interpolates pressures within the left ventricle from blood pressures gathered without directly sensing blood pressure in the left ventricle.

Abstract: Techniques are provided for use in a pacemaker or implantable cardioverter/defibrillator (ICD) for distinguishing cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals sensed within a patient, such as hypoglycemia, hyperglycemia or other systemic conditions. In one example, the device detects changes in morphological features of cardiac signals indicative of possible cardiac ischemia within the patient, such as changes in ST segment elevation within an intracardiac electrogram (IEGM). The device determines whether the changes in the morphological features are the result of spatially localized changes within a portion of the heart and then distinguishes cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals based on that determination. In another example, the device exploits the interval between the peak of a T-wave (Tmax) and the end of the T-wave (Tend).

Abstract: An exemplary method includes detecting a QRS complex using cutaneous electrodes, during the QRS complex, detecting an R-wave of a ventricle using an intracardiac electrode, determining if the R-wave occurred during a first, predetermined percentage of the QRS complex width and, based at least in part on the determining, deciding whether a patient is likely to respond to cardiac resynchronization therapy. Such a method may set the predetermined percentage to approximately 50%. An exemplary model includes a parameter for a percentage for the timing of an EGM R-wave with respect to the total width of an ECG QRS complex. Various other exemplary methods, devices, systems, etc. are also disclosed.