Patent EP-2241348-A2 (EP)
Inventor: VOLLKRON MICHAEL
IPC: A61B5/053
Filed: 2010-03-16
Abstract: The cardiac monitor (20), which is connected or to be connected with a sensor for pressure- and volume data or equivalent substitute variables of the heart, comprises an evaluation unit for processing the input signals indicating the temporal progression of pressure- and volume data or equivalent substitute variables of the heart, an input for marker signals, which represent the defined results within the respective cardiac cycles including the time points of their occurrence, and an electrocardiogram signal input for an intracardiac or surface electrocardiogram signal. The cardiac monitor (20), which is connected or to be connected with a sensor for pressure- and volume data or equivalent substitute variables of the heart, comprises an evaluation unit for processing the input signals indicating the temporal progression of pressure- and volume data or equivalent substitute variables of the heart, an input for marker signals, which represent the defined results within the respective cardiac cycles including the time points of their occurrence, and an electrocardiogram signal input for an intracardiac or surface electrocardiogram signal. The evaluation unit is designed, so that it carries out a segmentation of the individual concluded cardiac cycles corresponding to the input signals and subsequently verifies the obtained segments of the input signals if a respective segment of the input signals represents a pressure-volume (pV) diagram, which corresponds to the specified quality requirements. The evaluation unit is designed to evaluate the successive signal value pairs of the input signals with respect to a peripheral direction of the pV-diagram represented by the signal value pairs, to determine the peripheral direction of the pV-diagram represented by the signal value pairs by evaluating the direction of two-dimensional vectors, in which a middle point of two-dimensional coordinate system generates with an origin in the center of the respective pV-diagram, to determine a vector for each measuring point (signal value pair) from the middle point of the coordinate system to a respective measuring point determined at the peripheral direction of the successive measuring points, to apply the peripheral direction of the pV-diagram represented by the signal value pairs, to detect invalid signal value pairs and optionally to correct the invalid signal value pairs for creating a corrected pV-diagram, and to reject the signal value pairs, which have a deviated peripheral direction for creating the corrected pV-diagram. The evaluation unit is designed to carry out the segmentation of the input signals based on the marker signals to be received over the marker signal input, and to carry out the segmentation of the input signals based on morphological features of the pV-diagram represented by the signal value pairs, to carry out an approximation of the pV-diagram by replacement functions such as ellipse, rectangle and/or trapezoid for obtaining the corrected pV-diagram, to automatically detect and correct the intersection points of the pV-diagram, which yields by connecting the successive signal value pairs for creating the corrected pV-diagram and/or for creating the corrected pV-diagram by calculating an envelope curve that encloses all measuring points and/or to approximate a sequence of signal value pairs representing the pV-diagram by parameter-optimized functions for obtaining the corrected pV-diagram. The evaluation unit is designed to carry out the segmentation of the input signals based on intracardiac signals to be received over the electrocardiogram signal input, to determine a maximum envelope curve that does not enclose measuring point of signal segment represented by the pV-diagram or to determine a minimum envelope curve that encloses most measuring points of signal segments represented by the pV-diagram. The evaluation unit is designed to compare the corrected pV-diagram with the original uncorrected pV-diagram before a further evaluation, and to determine the comparison based on the quality criteria such as the number of corrected or rejected signal value pairs, differences in morphology, surface difference, ratio of circumference to surface, gravitational point displacement or distance between final and starting point depending on a respective comparison results if the respective corrected pV diagram suits or does not suit for the further evaluation. The evaluation unit is configured to derive a value for parameters from pV diagram represented by the respective signal value pairs in the case of further evaluation, where the parameters are contractility index, end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, effective arterial elastance, external work, potential energy, pressure-volume surface, ratio of external work and potential energy, arterial-ventricular coupling, end-systolic pressure and preload-recruitable stroke-work. The cardiac monitor is connected with a cardiac stimulator and is formed to influence the delivery of stimulation pulses by the cardiac stimulator. The evaluation unit is designed to stimulate the local changes of the filling conditions or contractility index by a variation of stimulation parameters such as atrioventricular delay time, interventricular delay time or cardiac cycle duration in the case of further evaluation for determining a respective residual volume Vo, or to apply the derived parameters for simultaneous optimization of the atrioventricular delay time, interventricular delay time and/or the stimulation frequency, in which the atrioventricular delay time, interventricular delay time and/or the stimulation frequency are varied until a global optimum of derived parameter is reached. The evaluation unit is configured to apply an automatic detection of transient changes in the contractility index, the preload or the postload for updating a current value of the residual volume Vo in the case of further evaluation. The values of derived parameters are determined and stored over a time, where the progressions are used for observing the patients or used as input parameter for prediction algorithms.