Abstract: An oxygen sensor (1, 2, 3, 4, 5) comprises a working electrode (WE) and a comparatively larger Ag/AgCl reference electrode (RE). A floating voltage between the electrodes (WE, RE) is temporarily retained and a measurement voltage is applied to between the electrodes (WE, RE) during a first period to cause reduction of oxygen and production of an evoked current at the working electrode (WE). The temporarily retained floating voltage is then applied between the electrodes (WE, RE) during a second period to produce a current out from the working electrode (WE). The pO2 in a liquid medium is then representative of a measured net charge to the working electrode (WE) equal to a sum of a charge transferred to the working electrode (WE) during at least a last part of the first period and a charge transferred to the working electrode (WE) during at least a last part of the second period.

Abstract: An oxygen sensor (1, 2, 3, 4, 5) comprises a working electrode (WE) and a comparatively larger Ag/AgCl reference electrode (RE). A floating voltage between the electrodes (WE, RE) is temporarily retained and a measurement voltage is applied to between the electrodes (WE, RE) during a first period to cause reduction of oxygen and production of an evoked current at the working electrode (WE). The temporarily retained floating voltage is then applied between the electrodes (WE, RE) during a second period to produce a current out from the working electrode (WE). The pO2 in a liquid medium is then representative of a measured net charge to the working electrode (WE) equal to a sum of a charge transferred to the working electrode (WE) during at least a last part of the first period and a charge transferred to the working electrode (WE) during at least a last part of the second period.

Abstract: Systems and methods for optimizing the stimulation of a heart of a patient are disclosed herein. The method comprises delivering pacing therapy to the patient according to a pacing therapy setting schedule, using specific pacing intervals via specific electrode configurations. Further, sinus rate values are recorded over at least one cardiac cycle at each pacing therapy setting and it is determined whether a sinus rate value satisfies predetermined measurement conditions, wherein sinus rate values are used for trending the sinus rate over time if the measurement conditions are satisfied. The accepted sinus rate values, i.e. values that satisfy the measurement conditions, are trended over time, wherein each trended sinus rate value is created based on recordings from at least one cardiac cycle. A preferred pacing therapy setting is determined to be the pacing therapy setting that provides a lowest sinus rate.

Abstract: Systems and methods for optimizing the stimulation of a heart of a patient are disclosed herein. The method comprises delivering pacing therapy to the patient according to a pacing therapy setting schedule, using specific pacing intervals via specific electrode configurations. Further, sinus rate values are recorded over at least one cardiac cycle at each pacing therapy setting and it is determined whether a sinus rate value satisfies predetermined measurement conditions, wherein sinus rate values are used for trending the sinus rate over time if the measurement conditions are satisfied. The accepted sinus rate values, i.e. values that satisfy the measurement conditions, are trended over time, wherein each trended sinus rate value is created based on recordings from at least one cardiac cycle. A preferred pacing therapy setting is determined to be the pacing therapy setting that provides a lowest sinus rate.

Abstract: A first ventricle is stimulated at a stimulation site, a point of time for arrival at the AV node for at least one depolarization wave resulting from the stimulation is estimated and a first activation time interval substantially corresponding to the time interval required for at least one depolarization wave to travel from the stimulation site in the first ventricle to the AV node is computed. A similar process is used to compute a second activation time interval for the other ventricle. Based on these activation time intervals and a difference between the intervals, a pacing therapy can be determined.

Abstract: Systems and methods for optimizing the stimulation of a heart of a patient are disclosed herein. The method comprises delivering pacing therapy to the patient according to a pacing therapy setting schedule, using specific pacing intervals via specific electrode configurations. Further, sinus rate values are recorded over at least one cardiac cycle at each pacing therapy setting and it is determined whether a sinus rate value satisfies predetermined measurement conditions, wherein sinus rate values are used for trending the sinus rate over time if the measurement conditions are satisfied. The accepted sinus rate values, i.e. values that satisfy the measurement conditions, are trended over time, wherein each trended sinus rate value is created based on recordings from at least one cardiac cycle. A preferred pacing therapy setting is determined to be the pacing therapy setting that provides a lowest sinus rate.

Abstract: An implantable medical device comprises a connector connectable to an implantable oxygen sensor configured to generate a sensor signal representative of oxygen concentration in coronary sinus blood in a subject's heart. An ischemia detector is connected to the connector and configured to detect an ischemic event in the heart if the sensor signal indicates a temporary decrease in oxygen concentration in the coronary sinus blood below a normal level followed by a temporary increase in oxygen concentration in the coronary sinus blood above the normal level.

Abstract: The present invention relates generally to medical devices for electrode positioning during implantation procedures. A cardiac signal measuring device measures cardiac signals sensitive to inherent differences between cardiac tissue and blood using at least one electrode of a medical lead arranged at a distal tip of the medical lead and at least a second electrode arranged at a distance from the distal electrode and being connectable to the measuring unit. An analyzing module acquires cardiac signals measured during predetermined measurement sessions. The analyzing module determines at least one cardiac signal value based on the cardiac signals for each measurement session and analyzes changes of the cardiac signal values between different measurement sessions to determine a position of the electrode relative a tissue border. A maximum of the change of the cardiac signal values between two successive measurement sessions indicates that the electrode has reached the tissue border.

Abstract: The present invention relates generally to implantable medical devices and more particularly to systems and methods for stimulating a heart of a patient. A first ventricle is activated by delivering stimulation to at least one stimulation site, a point of time for arrival at the AV node for at least one depolarization wave resulting from the stimulation in the first ventricle is estimated and a first activation time interval substantially corresponding to the time interval required for at least one depolarization wave to travel from the stimulation site in the first ventricle to the AV node using the estimated point of time for arrival of the depolarization wave and a point of time for delivery of stimulation is computed. Thereafter, the other ventricle is stimulated by delivering stimulation to at least one stimulation site.

Abstract: An implantable device monitors and treats heart failure, pulmonary edema, and hemodynamic conditions and in some cases applies therapy. In one implementation, the implantable device applies a high-frequency multi-phasic pulse waveform over multiple-vectors through tissue. The waveform has a duration less than the charging time constant of electrode-electrolyte interfaces in vivo to reduce intrusiveness while increasing sensitivity and specificity for trending parameters. The waveform can be multiplexed over multiple vectors and the results cross-correlated or subjected to probabilistic analysis or thresholding schemata to stage heart failure or pulmonary edema. In one implementation, a fractionation morphology of a sensed impedance waveform is used to trend intracardiac pressure to stage heart failure and to regulate cardiac resynchronization therapy. The waveform also provides unintrusive electrode integrity checks and 3-D impedancegrams.

Abstract: In a method and a device for determining the posture of a patient, a bio-impedance measurement device, having a number of electrodes configured to interact with the patient in a number of different electrode configurations, is operated to initiate a patient posture determining session by measuring an impedance value of the patient with the electrodes in at least one configuration among the number of configurations. A reference impedance value from among a number of stored reference impedance values for the at least one configuration is selected. The number of stored reference impedance values are respectively associated with different postures of the patient, and the posture associated with the selected reference impedance value represents a candidate posture. The measured impedance value is compared with the selected reference impedance value, thereby obtaining a comparison result.

Abstract: An implantable medical device, IMD, (100) is connectable to at least one ventricular lead (210) having a ventricular basal electrode (214) and a ventricular apical electrode (212). The IMD (100) comprises a pulse generator (120) for generating pacing pulses applied to a heart (10) through the ventricular lead (210). The operation of this pulse generator (120) is controlled by a controller (130) that is configured to control the pulse generator to first deliver a pacing pulse to the ventricular basal electrode (214) to stimulate the basal portion of the ventricle (12, 14) before a pacing pulse is delivered to the apical portion of the ventricle (12, 14) by the ventricular apical electrode (212). This pulse sequence achieves a biologically more correct cardiac stimulation and a contraction pattern that reduces the risk for valvular regurgitation.

Abstract: Techniques are provided for controlling therapy provided by the implantable cardiac stimulation device based on cardiogenic impedance. A cardiogenic impedance signal (or intracardiac impedance signal) is an impedance signal representative of the beating of the heart of the patient in which the device is implanted. The cardiogenic impedance signal is sensed along a sensing vector passing through at least a portion of the heart so that the sensed impedance is affected by the mechanical beating of the heart along that sensing vector. Pacing therapy is automatically and adaptively adjusted based on the cardiogenic impedance signal. For example, pacing timing parameters such as the atrioventricular delay and the inter-ventricular delay may be adjusted. Preferably, the adjustments are adaptive, i.e. the adjustments are performed in a closed-loop so as to adapt the adjustments to changes in the cardiogenic impedance signal so as to optimize therapy.

Abstract: The present invention relates generally to medical devices for electrode positioning during implantation procedures. A cardiac signal measuring device measures cardiac signals sensitive to inherent differences between cardiac tissue and blood using at least one electrode of a medical lead arranged at a distal tip of the medical lead and at least a second electrode arranged at a distance from the distal electrode and being connectable to the measuring unit. An analyzing module acquires cardiac signals measured during predetermined measurement sessions. The analyzing module determines at least one cardiac signal value based on the cardiac signals for each measurement session and analyzes changes of the cardiac signal values between different measurement sessions to determine a position of the electrode relative a tissue border. A maximum of the change of the cardiac signal values between two successive measurement sessions indicates that the electrode has reached the tissue border.

Abstract: A method for operating an implantable medical device to obtain substantially synchronized closure of the mitral and tricuspid valves based on sensed heart sounds includes sensing an acoustic energy; producing signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; calculating a pulse width of such a signal; and iteratively controlling a delivery of the ventricular pacing pulses based on calculated pulse widths of successive heart sound signals to identify an RV interval or VV interval that causes a substantially synchronized closure of the mitral and tricuspid valve. A medical device for optimizing an RV interval or VV interval based on sensed heart sounds implements such a method and a computer readable medium encoded with instructions causes a computer to perform such a method.

Abstract: An implantable medical device applies an electric signal over two electrodes and measures the resulting electric signal over a candidate pair of neighboring electrodes on a lead for a first heart ventricle or over a candidate electrode of the lead and a case electrode. An impedance signal is determined for each candidate pair or electrode based on the applied signal and the measured resulting signal. A time difference between start of contraction in a second ventricle and the timing of local myocardial contraction as identified from the impedance signal at the site of the candidate pair or electrode is determined for each candidate pair or electrode. An optimal pacing electrode is selected to correspond to one of the electrodes of the candidate pair having the largest time difference or the candidate electrode having largest time difference.

Abstract: An implantable device monitors and treats heart failure, pulmonary edema, and hemodynamic conditions and in some cases applies therapy. In one implementation, the implantable device applies a high-frequency multi-phasic pulse waveform over multiple-vectors through tissue. The waveform has a duration less than the charging time constant of electrode-electrolyte interfaces in vivo to reduce intrusiveness while increasing sensitivity and specificity for trending parameters. The waveform can be multiplexed over multiple vectors and the results cross-correlated or subjected to probabilistic analysis or thresholding schemata to stage heart failure or pulmonary edema. In one implementation, a fractionation morphology of a sensed impedance waveform is used to trend intracardiac pressure to stage heart failure and to regulate cardiac resynchronization therapy. The waveform also provides unintrusive electrode integrity checks and 3-D impedancegrams.

Abstract: The present invention relates generally to methods and systems for optimizing stimulation of a heart of a patient. Hemodynamical index signals reflecting a mechanical functioning of a heart of a patient are recorded at different hemodynamical states. Corresponding hemodynamical reference signals at corresponding hemodynamical states are recorded. At least one hemodynamical index parameter is extracted from the recorded hemodynamical index signals. The at least one hemodynamical index parameter is a measure of the mechanical functioning of the heart and a hemodynamical index model is created, wherein the hemodynamical index model is based on the at least one hemodynamical index parameter and a comparison between output results from the hemodynamical index model and corresponding hemodynamical reference signals. From this hemodynamical index model, a hemodynamical index can be derived, which then can be used in determining patient customized cardiac pacing settings of the cardiac stimulator.

Abstract: An implantable medical device has an impedance determiner for determining a cardiogenic impedance signal based on electric signals sensed by connected electrodes. A parameter calculator processes the impedance signal to calculate an impedance parameter representative of the cardiogenic impedance in connection with the diastolic phase of a heart cycle. This parameter is then employed by the device for monitoring acute decompensated heart failure status of a subject.

Abstract: An ischemia detecting system has an implantable medical device connectable to an LV cardiac catheter with sensors for generating sensor signals representative of the concentration of a constituent in coronary venous blood at different sites in the coronary venous system. The sensor signals are co-processed by the system to detect an ischemic region of the subject's heart based on a relation between the sensor signals. The detection of the particular ischemic cardiac region is possible by conducting the concentration monitoring on either sides of a branching vein in the coronary venous system and co-processing the sensor signals.