Device and system for visual three-dimensional presentation of ECG data
View Patent ↗The invention relates to the analysis of ECG data by exploiting computerized three-dimensional spatial presentation of the measured data using the vector concept. A three-dimensional presentation of the human heart may be correlated with waveforms specific for standard ECG or derived ECG signals based on the dipole approximation of the heart electrical activity. The three-dimensional heart model may be rotated, and the ECG signals are interactively linked to the model. In the visualization process, different types of signal presentation may be used, including graphical presentation of the heart vector hodograph, graphical presentation of the signal waveform in an arbitrary chosen point on the heart, and graphical presentation of the map of equipotential lines on the heart in a chosen moment. Additional tools for analyzing ECG data are also provided which may be interactively used with the display tools.
1. A device for analyzing cardiac electrical activity comprising:
a data input for obtaining ECG data measured from a plurality of sites on the surface of a patient's body;
a signal processing module coupled to the data input and which computes a normalized time variable heart vector that represents size and orientation of a time varying electrical dipole approximating the electrical activity of a patient's body, wherein the normalized time variable heart vector is normalized by a normalization factor computed by computing a lead normalization factor from each of at least three actual ECG lead sites on the surface of a patient's body; wherein each lead normalization factor is a function of measured voltage over time from the actual lead site, the time variable heart vector, and a lead vector corresponding to the actual lead site; and the normalization factor is selected from within the range defined by the lead normalization factors; and
an output coupled to the signal processing module and which reports the normalized time variable heart vector.
2. The device of claim 1 , wherein the time variable heart vector is normalized without changing the direction of the time variable heart vector.
3. A device for visualizing cardiac electrical activity comprising:
a data input which obtains ECG data measured from a plurality of lead sites on the surface of a patient's body;
a signal processing module coupled to the data input and which generates a model heart and derives a normalized time variable heart vector wherein the time variable heart vector is normalized by a normalization factor computed by computing a lead normalization factor from each of at least three actual lead sites; wherein each lead normalization factor is a function of measured voltage over time from the actual lead site, the time variable heart vector, and a lead vector corresponding to the actual lead site; and the normalization factor is selected from within the range defined by the lead normalization factors;
a display coupled to the signal processing module and which displays the cardiac electrical signal using a representation of a three dimensional image of the model heart; and
a user input coupled to the signal processing module and which allows a user to select a perspective view of the model heart and the corresponding cardiac electrical signal.
4. An article of manufacture encoded with computer readable information produced by the method including:
obtaining ECG data measured at a plurality of actual lead sites on the surface of a patient's body;
computing from the ECG data measured at the plurality of actual lead sites, a time variable heart vector that represents size and orientation of a time varying electrical dipole that approximates electrical heart activity and that has an origin near the center of the patient's heart;
computing a normalization factor by computing a lead normalization factor from each of at least three actual lead sites; wherein each lead normalization factor is a function of measured voltage over time from the actual lead site, the time variable heart vector, and a lead vector corresponding to the actual lead site; and the normalization factor is selected from within the range defined by the lead normalization factors; and
producing information concerning a normalized time variable heart vector by scaling the time variable heart vector by the normalization factor.
5. A system using ECG data measured at a plurality of actual lead sites on the surface of a patient's body to produce a representation of cardiac electrical activity on a display screen, the system comprising:
a signal processing module which computes a time variable heart vector from the ECG data measured at the plurality of actual lead sites, wherein the heart vector represents size and orientation of a time varying electrical dipole that approximates electrical heart activity and that has an origin near the center of the patient's heart; further where the signal processing module computes a normalized heart vector from the heart vector and a normalization factor, wherein the normalization factor is computed by computing a lead normalization factor from each of at least three actual lead sites; wherein each lead normalization factor is a function of measured voltage over time from the actual lead site, the time variable heart vector, and a lead vector corresponding to the actual lead site; and the normalization factor is selected from within the range defined by the lead normalization factors;
an interactive visualization module coupled to the signal processing module and comprising:
a display, wherein the visualization module provides a three dimensional heart representation on the display, wherein the heart representation is oriented in the same coordinates as the heart vector; and
an input coupled to the signal processing module and which indicates on the display a designated position on the heart representation;
further, wherein the signal processing module produces information concerning an electrical potential corresponding to the designated position.