Abstract: Methods for assessing, diagnosing and treating medical conditions using SvO2 and hematocrit measurements alone, or in combination with other measurements related to cardiac activity are provided. These includes methods for distinguishing true anemia from diluted anemia, methods for anemia detection, methods for measuring disease progression based on anemia trending, methods for managing therapy delivery, methods for managing heart failure drug therapies, methods for cardiac output optimization based on SvO2, methods for cardiac resynchronization therapy lead placement, method for detection of heart failure decompensation, and methods to monitor and treat systolic versus diastolic heart failure are provided.

Abstract: Techniques are provided for use by implantable medical devices for determining a preferred or optimal pair of electrodes for delivering biventricular pacing therapy. In one example, the implantable device is equipped with a right ventricular (RV) lead and a multi-pole left ventricular (LV) lead. Briefly, for each of a selected set of RV/LV electrode pairs, electrocardiac parameters are detected within a patient in which the device is implanted, including parameters representative of an intrinsic biventricular electrical separation between LV and RV and parameters representative of a mechanical contraction delay in the LV. An optimal RV/LV electrode pair is then determined for delivering biventricular pacing based on an analysis of the intrinsic biventricular electrical separation and the mechanical contraction delay. Pacing latency, pacing delay from LV to RV, and the maximum slope of an LV evoked response may be used as proxies or surrogates for mechanical contraction delay.

Abstract: A medical device is provided that comprises a lead assembly configured to be at least partially located proximate to the heart. The lead assembly includes an extra-cardiac (EC) electrode to be positioned proximate to at least one of a superior vena cava (SVC) and a left ventricle (LV) of a heart. The lead assembly includes a subcutaneous remote-cardiac (RC) electrode configured to be located remote from the heart such that at least a portion of the greater vessels are interposed between the RC electrode and the EC electrode to establish an extra-cardiac impedance (ECI) vector. The processor module measures extra-cardiac impedance along the ECI vector to obtain ECI measurements. The processor module assesses a hemodynamic performance based on the ECI measurements.

Abstract: A subcutaneous implantable cardiac device system applies defibrillation currents in pathways aligned with the heart's own electrical system to decrease defibrillation thresholds. In one implementation, one or more subcutaneous sensors detect ventricular fibrillation. Positioning of subcutaneous sensors and filtering result in improved sensing with reduced noise. A subcutaneous patch component of the system that is in communication with a subcutaneous pacemaker or cardioverter-defibrillator may perform the sensing and apply the defibrillation. The subcutaneous patch may include one or more electrodes that perform both sensing and defibrillation. Variations of the subcutaneous patch may include battery and capacitor for generating onboard defibrillation current and may also include a microprocessor for advanced programmable operation.

Abstract: Tachyarrhythmia is treated by applying anti-tachycardia pacing through at least one multi-site electrode set located on, in or around the heart. The electrode set is arranged and located such that an electrical activation pattern having a wave-front between substantially flat and concave is generated through a reentrant circuit associated with the tachyarrhythmia. The electrode set may be one of a plurality of predefined, multi-site electrode sets located on, in or around the atria. Alternatively, the electrode set may be formed using at least two selectable electrodes located on, in or around the atria.

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.

Abstract: Systems and methods are provided for detecting and responding to excessive heating of implantable medical device leads, such as leads used with pacemakers or implantable cardioverter-defibrillators (ICDs), during a magnetic resonance imaging (MRI) procedure. In one example, a critical temperature is determined for the lead that is representative, e.g., of the temperature at which tissue damage might occur or pacing/sensing might be significantly impaired. A temperature threshold is then set based on the critical temperature by subtracting a predetermined safety margin. Lead temperatures are then sensed during the MRI procedure. The lead temperatures are compared against the threshold and suitable warnings are transmitted to an external monitoring system if lead temperatures exceed their thresholds so that the attending personnel can take corrective action.

Abstract: An exemplary method includes detecting a change in state of a cardiac valve, detecting elongation of the left ventricle substantially along its major axis, determining a time difference between the change in state of the cardiac valve and the elongation of the left ventricle and, based at least in part on the time difference, deciding whether a diastolic abnormality exists. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: To provide radio-frequency (RF) bandstop filtering within an implantable lead, such as a pacemaker lead, one or more segments of the tip and ring conductors of the lead are formed as insulated coils to function as inductive band stop filters. By forming segments of the conductors into insulated coils, a separate set of discrete or distributed inductors is not required, yet RF filtering is achieved to, e.g., reduce lead heating during magnetic resonance imaging (MRI) procedures. To enhance the degree of bandstop filtering at the RF signal frequencies of MRIs, additional capacitive elements are added. In one example, the ring electrode of the lead is configured to provide capacitive shunting to the tip conductor. In another example, a capacitive transition is provided between the outer insulated coil and proximal portions of the ring conductor. In still other examples, conducting polymers are provided to enhance capacitive shunting. The insulated coils may be spaced at ¼ wavelength locations.

Abstract: A conducting sheath is provided along at least a portion of an implantable medical device lead, and preferably along substantially its entire length, for mitigating heating problems arising during magnetic resonance imaging (MRI) procedures, particularly problems arising due to a problem described herein as the “coiling effect.” During device implant, the clinician may elect to wrap or coil excess proximal portions of leads around or under the medical device being implanted. Thereafter, during MRI procedures, shunt capacitance may develop between the housing of the implantable device and insulated coils within the proximal portions of the lead that are near the device, resulting in greater lead heating during the MRI. The conducting sheath helps suppress induced currents and also reduces or eliminates shunt capacitance. The conducting sheath may be, for example, formed using a metal mesh or a conducting polymer tube incorporating non-ferrous metal powders. The sheath may be formed in ¼ wavelength segments.

Abstract: An exemplary method includes implementing a cardiac pacing therapy capable of delivering bi-ventricular stimulation, deciding if the therapy calls for bi-ventricular stimulation and, if the therapy calls for bi-ventricular stimulation, comparing an interventricular conduction delay to a threshold and based on the comparing, deciding whether to enable a capture detection algorithm. Various other exemplary methods, devices, systems, etc. are also disclosed.

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: Techniques are provided for use by implantable medical devices for controlling ventricular pacing using a multi-pole left ventricular (LV) lead. In one example, a single “V sense” test is performed to determine intrinsic interventricular conduction time delays (?n) between the RV electrode and each of the LV electrodes of the multi-pole lead. Likewise, a single “RV pace” test is performed to determine paced interventricular conduction time delays (IVCD_RLn) between the RV electrode and each of the LV electrodes. A set of “LV pace” tests is then performed to determine paced interventricular conduction time delays (IVCD_LRn) between individual LV electrodes and the RV electrode. Optimal or preferred interventricular pacing delays are determined using the intrinsic interventricular conduction delay (?n) values and a set of interventricular correction terms (?n) determined from the results of the RV pace test and the set of LV pace tests. With these techniques, overall test time can be reduced.

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: Techniques are provided for use by implantable medical devices for controlling multi-site left ventricular (MSLV) pacing using a multi-pole left ventricular (LV) lead. In various examples, a reduced number of “V sense”, “RV pace”, and “LV pace” tests are performed to determine preferred or optimal interventricular pacing delays (VV) for use with MSLV pacing. Additionally, techniques are described for sorting the order by which LV sites are to be paced during MSLV pacing. Furthermore, techniques are described for detecting and addressing circumstances where AV/PV delays are longer than corresponding AR/PR delays during MSLV.

Abstract: An implantable medical lead is described herein wherein the lead includes a tubular body, an electrode, a lead connector end and a helical conductor. The tubular body includes a proximal end and a distal end. The electrode is coupled to the body near the distal end. The lead connector end is coupled to the body near the proximal end. The helical conductor coil extends through the body from the lead connector end to the electrode. In extending through the body, the helical conductor coil first extends distally for a distance, then proximally for the distance, and then distally for the distance within a single helical layer of the helical conductor coil. The electrode may be a ring electrode.

Abstract: An implantable lead comprises a lead connector and an electrode configured to perform at least one of a sensing operation and delivery of electrical energy. The implantable lead also includes a lead body having a proximal end portion and a distal end portion with the connector located at the proximal end and the electrode located at the distal end. The lead body of the implantable lead has a length that includes a lumen that extends longitudinally between the distal and proximal end portions. The implantable lead further includes a coil conductor that has spiral sections wound within the lumen and extend from the lead connector along the lumen. The coil conductor couples the lead connector to the electrode. The coil conductor has an insulation material provided on at least a segment of the coil conductor. The insulation material has a dielectric constant set such that the coil conductor forms a distributed band stop filter when exposed to a known RF magnetic field.

Abstract: An exemplary method includes detecting a change in state of a cardiac valve, detecting elongation of the left ventricle substantially along its major axis, determining a time difference between the change in state of the cardiac valve and the elongation of the left ventricle and, based at least in part on the time difference, deciding whether a diastolic abnormality exists. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: An implantable lead includes a lead body, having a distal end and a proximal end, configured to be implanted in a patient. An electrode assembly is provided at the distal end of the lead body, wherein the electrode assembly includes an electrode that is configured to deliver stimulating pulses. The electrode extends between a base and a tip at a distal end of the electrode. A shielding member is provided on the electrode assembly and is positioned to cover at least a portion of the electrode to electrically shield the electrode from RF fields. Optionally, the shielding member may include a shielding conductor that wraps about and extends longitudinally along a length of the electrode from the base to the tip. The shielding conductor may extend from the proximal end of the lead body at least to the distal end of the lead body.

Abstract: An exemplary method includes providing surface ECG information acquired using a multi-lead ECG system, providing geometric information acquired using a magnetic resonance imagine system, X-ray imaging system or an ultrasound system and determining one or more stimulation sites for stimulation of the left ventricle based at least in part on the ECG information and the geometric information. Various other exemplary methods, devices, systems, etc., are also disclosed.