Abstract: A new model is provided for understanding and exploiting impedance or admittance values measured by implantable medical devices, such as pacemakers or cardiac resynchronization devices (CRTs.) The device measures impedance along vectors extending through tissues of the patient between various pairs of electrodes. The device then converts the vector-based impedance measurements into near-field individual electrode-based impedance values. This is accomplished, in at least some examples, by converting the vector-based impedance measurements into a set of linear equations to be solved while ignoring far-field contributions to the impedance measurements. The device solves the linear equations to determine the near-field impedance values for the individual electrodes, which are representative of the impedance of tissues in the vicinity of the electrodes.

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 processor that determines impedance data reflective of the transvalvular impedance of a heart valve of a heart during a heart cycle. The determined impedance data are processed by a representation processor that estimates diastolic and systolic transvalvular impedance representations. A condition processor determines the presence of any heart valve malfunction, such as valve regurgitation and/or stenosis, of the heart valve based on the estimated diastolic and systolic transvalvular impedance representations.

Abstract: An implantable medical device measures an AV delay in connection with measurement of N physiological patient parameters. The parameters are used for identifying a sub-space of an N-dimensional parameter space. An expected AV delay is assigned to the identified sub-space based on the measured AV delay, where the parameter space with expected AV delays constitute decision support information to be used by the device for performing a selective heart pacing. This selective pacing is performed based on a priori probability determined using the support information and a measured set of N parameters. The a priori probability represents the probability of successful AV conduction at a current patient condition determined based on the measured parameters.

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.

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 implantable medical device applies an electric signal to at least a portion of a heart in a subject. A resulting electric signal is collected from the heart and is used together with the applied signal for determining a cardiogenic impedance signal. The impedance signal is processed in order to estimate an isovolumetric contraction time, an isovolumetric relaxation time and an ejection time for a heart cycle. These three time parameters are employed for calculating a Tei-index of the heart. The Tei-index can be used as myocardial performance parameter in heart diagnosis and/or cardiac therapy adjustment.

Abstract: An implantable heart stimulator has an impedance measurement a cardiogenic impedance waveform using an impedance configuration arranged to measure myocardial contractility of the heart. The heart stimulator further has a calculating unit that calculates an estimate value being related to at least two impedance values of the waveform, or of an average waveform of several consecutive waveforms, during a predetermined time period of the waveform, or average waveform, the calculated estimate value being an estimate of the left ventricular (LV) systolic pressure.

Abstract: An implantable medical device has an event detector that detects a predetermined cardiac event during a heart cycle of a subject. A reference time is assigned to this detected cardiac event. An onset detector detects the onset of ventricular filling of the heart during the heart cycle. The relative time of the detected filling onset is determined based on the assigned time reference. An increased risk of heart failure of the subject is automatically determined based on the determined relative time for the filling onset. Generally, a reduction in the relative time, as determined at different points in time, indicates an increased heart failure risk or the presence of a heart failure condition.

Abstract: An implantable medical device has a detector for detecting an arrhythmia event of a subject's heart and generating an arrhythmia signal based on the detected event. An impedance determining unit determines impedance data representative of blood aggregation level of blood present in a cavity, such as heart chamber, of the subject. An anti-arrhythmia unit of the device is arranged for applying electric anti-arrhythmia treatment to at least a portion of the heart. This unit is conditionally operable based on the arrhythmia signal and the impedance data. The risk blood aggregates and clots obstructing blood vessels following anti-arrhythmia treatment is significant reduces by conditioning the treatment based on the aggregation level representing impedance data.

Abstract: An implantable medical device comprises a signal generator for generating a current signal having a frequency in a frequency window slightly less than the ?-dispersion frequency of a tissue and applying the signal over the tissue. A signal measurer measures the resulting voltage signal and an impedance parameter is calculated from the applied and measured signal by a parameter determiner. A status monitor monitors the permeability status of cell membranes in the tissue based on this impedance parameter.

Abstract: In a method and system for monitoring mechanical properties of a heart in a subject, multiple cardiogenic impedance values reflective of the impedance of the heart in connection with a transition from inhalation to exhalation in the subject are determined. Correspondingly, multiple cardiogenic impedance values reflective of the impedance of the heart in connection with a transition from exhalation to inhalation are determined. The impedance values are collectively processed to form a trend parameter. The value determination and processing is performed over several respiratory cycles spaced apart in time to form a plurality of trend parameters over time. The mechanical properties of the heart are monitored by processing these different trend parameters. The data collection and optionally at least a part of the data processing is performed by an implantable medical device.

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 medical device and method to monitor pulmonary artery pressure of a patient, a first parameter related to the right ventricular straight volume of the patient's is detected, and a second parameter related to the right ventricular ejection rate of the patient's heart, or related to the workload of the patient's heart, is also determined. A pulmonary pressure index is determined by combining the first and second parameters, with variations of the pulmonary pressure index indicating variations in the pulmonary artery pressure. Pulmonary artery hypertension can be monitored with such a device and method.

Abstract: In a device and a method for providing correlated measures for predicting potential occurrence of atrial fibrillation, an impedance of the patient is measured to obtain impedance information; cardiogenic data is determined from the information; respiratory data is determined from the information; at least one hemodynamic measure is calculated from the cardiogenic data and at least one apnea measure is calculated from the respiratory data; the hemodynamic and apnea measures are correlated such that the correlated measures can be utilized for predicting potential occurrence of atrial fibrillation.

Abstract: In an implantable heart monitoring device and a monitoring method, an impedance is measured across at least part of an atrium, such that variation of the impedance is related to the volume change of the atrium. Values are stored at different occasions that indicate the rate of change of the measured impedance. The stored values are determined such that, when the device is used in a living being, the variation of the stored values will be related to the variation of the speed with which the atrium is filled with blood during the atrial diastole.

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: In a method and a device for trending and prediction of monitored conditions or diseases, an REM sleep detector is provided to allow data collected during REM sleep to be separated from other data so stable and uniform conditions for data collection are achieved. The REM sleep detector can advantageously be provided inside an implantable medical device.

Abstract: In an implantable medical device and method for monitoring a lung deficiency in a patient, a housing containing a control circuit. Is implanted in a patient. The control circuit is configured to analyze one or more signals that represent the breathing of the patient. The control circuit is also configured to monitor a relationship between an expiratory phase and an inspiratory phase of the breathing cycle, or an analogous relationship, and to monitor a change in the lung deficiency by monitoring a change in this relationship.

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.