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: 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: 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 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 analyte measuring system has an implantable medical device having a signal source arranged for generating a current signal and electrodes for applying the current signal to a surrounding tissue in a subject body. The device measures a resulting voltage signal with the electrodes and calculates an impedance signal therefrom. The system comprises a signal processor arranged for generating an estimate of a concentration of an analyte in the tissue based on a spectrum analysis of the determined impedance signal.

Abstract: Implantable heart stimulator connectable to an electrode arrangement has a pulse generator adapted to deliver stimulation pulses to a heart of a subject; an impedance measurement unit adapted monitor at least one heart chamber of the heart of the subject to measure the impedance in the at least one monitored heart chamber for generating an impedance signal corresponding to the measured impedance. The impedance signal is applied to a processor where the signal is processed, according to specified criteria, and a fractionation index value is determined represented by the curve length of the impedance signal during a predetermined measurement period. The fractionation index value is a measure of different degrees of mechanical dyssynchrony of the heart.

Abstract: In a method and implantable medical device for ventricular tachyarrhythmia detection and classification, upon detection of a ventricular tachyarrhythmia based on an electrocardiogram signal, cardiogenic impedance data representative of ventricular volume dynamics are collected and used for classifying the detected tachyarrhythmia as stable or unstable. In the latter case but typically not in the former case, defibrillation shocks or other forms of therapy are applied to combat the unstable ventricular tachyarrhythmia.

Abstract: An implantable cardiac device has a heart stimulator for electrically stimulating the heart of a patient, detector that measures a physiologic parameter that is affected by the status of a cardiovascular disease associated with sympathetic activation, a signal processor that determines at least one of a low frequency, LF, and a very low frequency, VLF, Mayer wave component in the measured parameter, and analyzer that automatically analyzes the determined Mayer wave component in relation to a predetermined reference value to determine the status of the cardiovascular disease. The detector is a cardio-mechanical parameter detector that measures, as said physiologic parameter, a mechanical change in at least one of the four chambers of the heart. In a corresponding method for monitoring the status of a cardiovascular disease associated with sympathetic activation of a patient having an implantable electric heart stimulator a physiologic parameter affected by the cardiac disease is measured.

Abstract: In a method and an apparatus for creating hemodynamic sensor signal templates using an implantable medical device connectable to a patient heart activity of the patient is sensed in order to identify a paste or sensed sequence of events of a heart cycle. Hemodynamic sensor signals for consecutive heart cycles are sensed and the sensed hemodynamic sensor signals for consecutive heart cycles are stored. The sensed sensor signals are classified dependent on at least one predetermined heart event sequence condition. A template may be created using the classified sensor signals.

Abstract: In an implantable heart stimulator and a method for operation thereof, stimulation pulses are delivered to a heart. The amplitude of the delivered stimulation pulses can be selectively set. For setting the amplitude, threshold searches are performed at selected time intervals. Each threshold search determines a threshold value required for achieving capture. The amplitudes of the respective stimulation pulses are set to a value that exceeds the determined threshold value by a safety margin. The safety margin is selected as a function of the selected time intervals.

Abstract: In a method and medical device for detecting an ischemic episode and to determine a location of ischemia in a heart of a patient, an impedance measuring circuit measures the impedances in the tissue between electrodes of at least one electrode configuration according to a predetermined measurement scheme and an ischemia detector evaluates the measured impedance values using at least one reference impedance image of the heart to detect changes in the measured impedances that are consistent with an ischemia and to determine a location of the ischemia to at least one region of the image.

Abstract: An implantable heart monitoring system includes a housing configured for implantation in a subject, at least one sensor member implanted relative to the heart of the subject to detect an electrical signal related to cardiac activity of the heart, a control circuit in the housing, and a memory accessible by the control circuit.

Abstract: A method for detecting a condition of a heart of a patient using an implantable medical device, including the steps of sensing acoustic signals indicative of heart sounds of the heart of the patient; extracting signals corresponding to a first heart sound (S1) and a second heart sound (S2) from sensed signals; calculating an energy value corresponding to a signal corresponding to the first heart sound (S1) and an energy value corresponding to the second heart sound (S2); calculating a relation between the energy value corresponding to the first heart sound and the energy value corresponding to the second heart sound for successive cardiac cycles; and using at least one relation to detect the condition or a change of the condition. A medical device for determining the posture of a patient and a computer readable medium encoded with instructions are used to perform the inventive method.

Abstract: In a biventricular heart stimulator and a method for controlling such a biventricular heart stimulator, successive stimulation pulses are delivered to the ventricles of a heart such that stimulation pulses in a single heartbeat cycle are respectively first delivered to the first ventricle and then to the second ventricle. Capture or loss of capture in response to stimulation pulses delivered to one ventricle is detected. As a result of a detected loss of capture, preventative measures are taken for preventing loss of capture in the other ventricle.

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: A method for operating an implantable medical device to control a stimulation therapy includes the steps of: sensing an acoustic energy; producing acoustic signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; extracting a signal corresponding to a first heart sound (S1) from a measured acoustic signal; calculating an energy value corresponding to the extracted signal; storing the energy value corresponding to the first heart sound; and initiating an optimization procedure, the optimization procedure comprising the steps of: iteratively controlling a delivery of the pacing pulses based on successive energy values corresponding to successive first heart sound signals and determining an optimal PV interval or AV interval with respect to the energy values. A medical device and a computer readable medium to implement the method.

Abstract: An implantable cardiac stimulation device has an atrial detector that detects atrial events of a patient's heart, and a memory in which sequences of IEGM signals are stored, having a predetermined length, and an analyzing unit that analyzes the sequences to determine if the stored sequences contain atrial events having a lower amplitude than the current sensitivity setting of the atrial detector. A control unit is connected to the atrial detector to adjust the sensitivity setting thereof to a threshold that is determined based on the aforementioned analysis of the IEGM signals.

Abstract: In an apparatus and method for detecting incipient heart failure of a patient. Impedance signals reflecting volume changes of the right ventricle and/or the right atrium of a heart of the patient are obtained. The impedance signals are processed to determine a first impedance parameter substantially reflecting a volume of the right ventricle, and a heart failure status is determined based on the first impedance parameter, wherein a decreasing first impedance parameter is determined to be an indication of a deterioration of the heart failure status.