Abstract: Techniques are provided for estimating optimal atrioventricular pacing delay values for use in pacing the ventricles based on features of an intracardiac electrogram (IEGM) signal. Briefly, atrioventricular pacing delay pacing values are set based upon the location of atrial repolarization events within the IEGM. In one example, the end of an atrial repolarization is identified, then the interval from the atrial depolarization to the end of the atrial repolarization is measured. The atrioventricular pacing delay is then set by subtracting an offset value from that interval so as to time delivery of V-pulses prior the end of atrial repolarization. In this manner, atrioventricular pacing delay values are set based only IEGM signals and hence can be set to optimal/preferred values by the device itself without requiring surface electrocardiogram (EKG) signals and Doppler echocardiography or other cardiac performance monitoring techniques.

Abstract: Embodiments of the present invention relate to implantable systems, and method for use therein, that can detect T-wave alternans. In accordance with specific embodiments of the present invention, intrinsic premature contractions of the ventricles are detected, and at least one metric of T-waves is measured in a specified number of beats that follow each detected intrinsic premature contraction of the ventricles. A determination of whether T-wave alternans are present is made based on the measured T-wave metrics. In alternative embodiments, rather than waiting for intrinsic premature contractions of the ventricles, premature contractions of the ventricles are caused on demand by inducing premature atrial contractions. In still other embodiments, a patient's vagus nerve is stimulated to simulate premature contractions of the ventricles. This abstract is not intended to be a complete description of, or limit the scope of, the invention.

Abstract: An exemplary method to reduce risk of ventricular oversensing includes sensing, in vivo, amplitude of electrical cardiac activity, comparing sensed amplitude to a low sensitivity threshold where if the comparing indicates that sensed amplitude does not meet or exceed the low sensitivity threshold then further comparing the sensed amplitude to a high sensitivity threshold and if the further comparing indicates that sensed amplitude meets or exceeds the high sensitivity threshold then determining that ventricular fibrillation may exist. Various exemplary devices, systems, methods, etc., are disclosed.

Abstract: A device and methods for automatically evaluating one or more patient physiological parameters and, upon determination that certain therapies are indicated, delivering therapeutic mechanical stimulations to tissue of the patient. The mechanical stimulations generally include vibrations delivered at frequencies somewhat higher or lower than an intrinsic frequency and the therapeutic vibrations are delivered to drive the intrinsic frequency towards a desired value. The device and methods more closely emulate natural physiologic feedback mechanisms and can reduce undesired side effects of other known therapies. The device can include a small and efficient electrical motor which is interconnected with a crank and link mechanism to generate oscillatory motion which is conducted to a flexible wall of a bio-compatible housing of the device.

Abstract: Techniques are described for efficiently detecting and distinguishing among cardiac ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. In one example, a preliminary indication of an episode of cardiac ischemia is detected based on shifts in ST segment elevation within the IEGM. In response, the implanted device then records additional IEGM data for transmission to an external system. The external system analyzes the additional IEGM data to confirm the detection of cardiac ischemia using a more sophisticated analysis procedure exploiting additional detection parameters. In particular, the external system uses detection parameters capable of distinguishing hypoglycemia, hyperglycemia and hyperkalemia from cardiac ischemia, such as QTmax and QTend intervals. Alternatively, the more sophisticated analysis procedure may be performed by the device itself, if it is so equipped. Other examples described herein pertain instead to the detection of atrial fibrillation.

Abstract: Methods and systems for performing pacing interval optimization are provided. One or more optimum pacing interval is determined for each of a plurality of different ranges of heart rate, different levels of autonomic tone, different body temperature ranges, or combinations thereof. The information (e.g., measures of hemodynamic response) collected to perform pacing interval optimization can be collected and stored in a table over disjoint periods of time. Such measures of hemodynamic performance are preferably relative measures, but can alternatively be absolute measures.

Abstract: An implantable cardiac stimulation device determines sudden cardiac death susceptibility of a heart. The device comprises a first measuring circuit that measures intrinsic rest rate of the heart, a second measuring circuit that measures heart rate response of the heart and a third measuring circuit that measures heart rate recovery of the heart. The device further comprises a comparator that compares the measured intrinsic rest rate, the measured heart rate response, and the measured heart rate recovery to respective first, second, and third standards and a response circuit that provides a predetermined response when the comparisons of the measured intrinsic rest rate, the measured heart rate response, and the measured heart rate recovery to the respective standards indicate a susceptibility of sudden cardiac death.

Abstract: An implantable medical device includes a pressure input, an excitation source, a detector module, and a processor. The pressure input is configured to be joined to a pressure sensor located proximate to a cardiac chamber of the heart. The pressure input receives pressure measurements representative of a pressure in the cardiac chamber. The excitation source is configured to deliver stimulation pulses to the heart. The detector module communicates with the pressure sensor to receive and compare the pressure measurements to a pressure threshold. The processor instructs the excitation source to deliver the stimulation pulses at a pressure-based rate based on the comparison of the pressure measurements to the pressure threshold.

Abstract: Techniques are described for delivering inotropic electrical therapy to myocardial tissue using an implantable cardiac stimulation device such as a pacemaker. In one example, electrical stimulation is applied by a pacemaker to the heart of a patient while taking into account dynamic trans-cardiac impedance waveforms measured within the patient. In another example, a series of subthreshold inotropic stimulation pulses are delivered just prior to delivery of a suprathreshold depolarizing pulse that triggers systole. Additional subthreshold inotropic stimulation pulses can also be delivered following the suprathreshold pulse. Preferably, the magnitudes of the inotropic pulses are incrementally increased prior to systole then decremented thereafter, thereby gradually recruiting myocardium that has differing thresholds for depolarization. Both techniques seek to improve myocardial contractility of diseased tissue by improving calcium flux.

Abstract: An implantable system applies tiered antitachycardia pacing (ATP) that may be combined with pre-pulsing therapy in order to reduce pain. In one implementation, an exemplary system applies a progression of increasingly potent pacing vectors, progressing in an initial tier from small electrodes inside the heart to later tiers that increasingly use a large electrode surface outside the heart. In the latter tiers, a pre-pulse may be added prior to each ATP pulse to reduce the sensation of pain.

Abstract: A shielded electrode assembly for sensing electrical signals within a nerve is disclosed. The assembly comprises a generally tubular, electrically insulating shield body, which may be reversibly secured to the nerve. An electrically conducting mesh is positioned on at least a portion of an outer surface of the shield body, defining a region of the assembly within which external electromagnetic radiation is significantly attenuated. The conducting mesh is formed by photolithography, providing substantially precise control over the mesh aperture and thus the frequency of radiation which is shielded. A plurality of electrodes are placed within the shielded region and configured so as to contact the nerve. This design allows the electrodes to sense nerve signals within an environment which is at least partially shielded from electromagnetic radiation, facilitating nerve sensing with reduced need for filtering or signal processing.

Abstract: An implantable therapy system including implantable stimulation and control components. The implantable components operate under a set of variable parameters that can be adjusted for improved performance for an individual patient. The implantable components are adapted to self-evaluate the patients physiologic performance and autonomously adjust an existing set of parameters to improve performance throughout an implantation period without requiring intervention of a clinician, for example with a physicians programmer. The implantable components can compare a patient's exhibited activity to a desired template of that activity to determine when adjustments are indicated. The template can be based on observations of one or more third parties exhibiting normal activity. The implantable components can adjust the operating parameters to improve synchrony of multiple heart chambers and/or to increase a peak contractility.

Abstract: An electro-mechanical activation probe obtains information pertaining to both myocardial electrical activity and myocardial mechanical activity at each of a plurality of locations relative to the myocardium of a heart chamber. For each location, the temporal difference between a feature of the electrical activity, such as the QRS complex of an IEGM, and a feature of the mechanical activity, such as the onset of myocardial contraction, is compared to obtain a mechanical activation delay. A stimulation electrode is then positioned at one of the locations based on the comparison. The electrode may be positioned at the location having the greatest mechanical activation delay. Other mechanical activity, such as contractual force, may be used in conjunction with the mechanical activation delay to determine the optimal electrode location.

Abstract: An implantable stimulation device that maps the location of irritable foci causing an atrial arrhythmia is provided by certain embodiments disclosed herein. The device may, for example, collect intra-cardiac data from a plurality of electrodes spatially distributed throughout a chamber of the heart. This data may be compared with data related to the location of each electrode and the electrical properties of the heart to approximate a point of origin for the atrial arrhythmia. Further embodiments may provide methods and systems for using this information to provide more efficient treatment of the atrial arrhythmia. For example, an optimized ATP pulse train may be determined based on the location of one or more irritable foci. Such an ATP pulse train may be applied to more efficiently terminate the atrial arrhythmia.

Abstract: An economical, repeatable, and non-invasive method and apparatus for the calibration of implantable pressure sensors that can minimize patient discomfort and risk of infection. In one embodiment, a calibration system for calibrating a first pressure sensor coupled to a management device and implanted into a human patient is provided. The calibration system includes a mouthpiece, a pump, a second pressure sensor, and a computer. The pump provides a positive pressure into an airway of the human patient via the mouthpiece. The second pressure sensor measures the airway pressure of the human patient, and the computer is coupled to the pump and monitors pressures measured by the first and second pressure sensors. Here, the computer also calculates one or more calibration constants based on the pressures measured by the first and second pressure sensors and provides the calibration constants to the management device to calibrate the first pressure sensor.

Abstract: An implanted cardioverter defibrillator (ICD) delivers an electrical therapy signal to the heart of a patient. When ventricular fibrillation or another condition of the heart requiring high voltage therapy is sensed, the therapy signal is delivered to the heart. When a partial short-circuit or other low impedance condition occurs, an over-current protection circuit will stop delivery of a shocking pulse. The ICD will then reduce the voltage of the shocking pulse and try again to deliver electrical therapy. This process is repeated until a voltage level is found that is able to deliver the electrical therapy without causing an over-voltage condition. Alternate lead configurations may also be tried in an attempt to find a signal path that is not affected by the low impedance or short-circuit condition.

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: Disclosed herein is an implantable pulse generator. The implantable pulse generator includes a header, a can and a feedthru. The header includes a lead connector block electrically coupled to a first conductor. The can is coupled to the header and includes a wall and an electronic component electrically connected to a second conductor and housed within the wall. The feedthru is mounted in the wall and includes an electrically insulating core, a PCB, a shield, a chip capacitor, a power circuit and a ground circuit. A first side of the PCB abuts against the core and a second side of the PCB abuts against an edge of the shield. The chip capacitor is mounted on the second side of the PCB. The chip capacitor is enclosed in a volume defined by an interior of the shield and the second side of the PCB. A first electrical contact of the chip capacitor is electrically coupled to the power circuit, which extends between the first and second conductors.

Abstract: A method of analyzing myocardial instability includes obtaining a physiological parameter representative of myocardial behavior over a set of cardiac cycles and determining reversal points in the physiological parameter over the set of cardiac cycles. The method also includes identifying myocardial instability based on the reversal points in the physiological parameter. A reversal point may correspond to a value of the physiological parameter, during a current cardiac cycle, that exceeds or is less than the values of the physiological parameter during prior and subsequent cardiac cycles. Optionally, the method includes calculating differences between values of the physiological parameter for consecutive cardiac cycles and detecting the reversal points when a current difference exceeds or is less than differences for prior and subsequent cardiac cycles.

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.