Method of examining dynamic cardiac electromagnetic activity and detection of cardiac functions using results thereof
View Patent ↗A method of examining cardiac electromagnetic activity over a heart for diagnosing the cardiac functions of the heart is disclosed. The method may include constructing a phase diagram of electromagnetic signals over a heart by collecting sets of time-dependent magnetic signals, determining the zeroth and the first derivations of each set of the magnetic signals at a given time, and categorizing the zeroth and the first derivations of the magnetic signals in either of the four phases: (+, +), (−, −), (+, −), (−, +). The method may also include monitoring a wave propagation of the magnetic signals.
1. A method of examining cardiac electromagnetic activity of a heart, the method comprising:
performing a magnetic measurement at a plurality of measurement positions of a subject to obtain a plurality of sets of spatially distributed, time-dependent magnetic signals, corresponding to the plurality of measurement positions;
constructing a fitting curve to each set of the spatially distributed, time-dependent magnetic signals;
determining zeroth and first derivations of the fitting curve each set of the spatially distributed, time-dependent magnetic signals at a given time;
categorizing the zeroth and the first derivations of the each set of the spatially distributed, time-dependent magnetic signals in one of four phases : (+, +), (−, −), (+, −), (−, +); and
mapping the resulting phase with regions of the heart.
2. The method of claim 1 , wherein the magnetic signals comprise a magnetic field component (B z ) normal to a surface of the subject.
3. The method of claim 1 , wherein the magnetic signals are two-dimensionally or three-dimensionally distributed over a heart of the subject.
4. The method of claim 1 , wherein the given time of the each set of the magnetic signals is at a turning point (TP) of the fitting curve at which a second derivation of the each set of the spatially distributed, time-dependent magnetic signals is zero.
5. The method of claim 4 , wherein the plurality of sets of spatially distributed, time-dependent magnetic signals is representative of an intramyocardial, electrical behavior of said subject, and exhibits features of at least a P-wave, a Q-wave, a R-wave, a S-wave and a T-wave, and the given time is at the turning point of a ST segment of the each set of the spatially distributed, time-dependent magnetic signals.
6. The method of claim 5 , wherein the each set of the magnetic signals is offset by zeroing an interval of the magnetic signals before the P-wave.
7. The method of claim 4 , wherein the first derivation of the each set of the magnetic signals is calculated at about 0.01 to about 0.15 second after the turning point.
8. A method of examining cardiac electromagnetic activity for diagnosing cardiac functions of a heart, the method comprising:
performing a non-contact magnetic measurement over a subject's thorax region at a plurality of measurement positions to obtain a plurality of sets of spatially distributed, time-varying magnetic signals of the heart of the subject, corresponding to the plurality of the measurement positions, wherein each set of the spatially distributed, time-varying magnetic signals is representative of an intramyocardial, electrical behavior of the subject and comprises features of at least a P-wave, a Q-wave, a R-wave, a S-wave and a T-wave;
offsetting the each set of the spatially distributed, time-varying magnetic signals;
constructing a fitting curve of polynomial function to each set of the off-set, spatially distributed, time-varying magnetic signals;
identifying a time point on the fitting curve that corresponds to a zero value of a second derivation of the each set of the off-set, spatially distributed, time-varying magnetic signals;
determining values of zeroth and first derivations for the fitting curve of the each set of the off-set, spatially distributed, time-varying magnetic signals at the time point corresponding to the zero value of the second derivation;
categorizing the zeroth and the first derivations of the each set of the off-set, spatially distributed, time-varying magnetic signals in one of four phases : (+, +), (−, −), (+, −), (−, +); and
mapping the resulting phases with regions of the heart.
9. The method of claim 8 , wherein the magnetic signals comprise a magnetic field component (B z ) normal to a surface of the subject.
10. The method of claim 8 , wherein a normally functioning region of the heart has the phases of (+, +) or (−, −), while an abnormally functioning region of the heart has the phases of (+, −), (−, +).
11. The method of claim 8 , wherein the step of offsetting is accomplished by zeroing an interval of the each set of the spatially distributed, time-varying magnetic signals before a P wave.
12. The method of claim 8 , wherein the first derivation of the magnetic signals is calculated at about 0.01 to about 0.15 second after the time point.
13. The method of claim 8 , wherein the phases (+, −) and (−, +) exist at an interface between the phase (+, +) and the phase (−, −).
14. The method of claim 8 , wherein the time point on the fitting curve that corresponds to the zero value of the second derivation of the each set of the off-set, spatially distributed, time-varying magnetic signals is at a ST segment.
15. The method of claim 8 , wherein the phases (+, +), (−, −), (+, −), (−, +) are used for defining a risk cutoff value for screening injured myocardium.
16. A method of examining cardiac electromagnetic activity of a heart of a subject for diagnosing cardiac functions, the method comprising:
performing a non-contact magnetic measurement over a thorax region of the subject at a plurality of measurement positions to obtain a plurality of sets of spatially distributed, time-varying magnetic field signals of the heart of the subject, wherein each set of the spatially distributed, time-dependent magnetic field signals at each measurement position exhibits features of at least a wave;
offsetting each set of the spatially distributed time-varying magnetic signals;
identifying a time (t max,chN ) corresponding to a local maximum (positive or negative) intensity of magnetic field of the wave of each set of the offset, spatially distributed time-varying magnetic signals at each measurement position; and
plotting a temporal evolution of the local maximum intensity of the magnetic field during a time interval of the wave to obtain a propagation behavior of the wave of the each set of the offset, spatially distributed time-varying magnetic signals.
17. The method of claim 16 , wherein each set of the spatially distributed, time-dependent magnetic field signals at each measurement position exhibits the features of at least a P-wave, a Q-wave, a R-wave, a S-wave, a T-wave or a combination thereof corresponding to that of an electrocardiography.
18. The method of claim 17 , wherein the wave is the T-wave.
19. The method of claim 17 , wherein for a normally functioning heart, a positive pole of the T-wave appears earlier than a negative pole of the T-wave.
20. The method of claim 17 , wherein for a normally function heart, a positive pole of the T wave originates close to an A-V node of the heart, and propagates toward a left ventricle, and continues to a left part of a cardiac apex of the heart.
21. The method of claim 17 , following an appearance of a positive pole of the T-wave at a left part of a cardiac apex of the heart, a negative of the T wave propagates from a right part of a cardiac apex toward a central part through a right ventricle.
22. The method of claim 17 , wherein for an abnormally functioning heart, a positive pole and a negative pole of the T wave originate from parts of the heart different from those of a normally functioning heart.
23. The method of claim 17 , wherein the each of the sets of the magnetic signals is offset by zeroing an interval of the magnetic signals before the P-wave.
24. The method of claim 16 , wherein the magnetic field signals comprise magnetic field components perpendicular (B z ) to a surface of the subject.
25. The method of claim 16 , wherein the propagation of the wave is applicable in diagnosing coronary artery diseases.
26. The method of claim 16 , wherein the propagation behavior of the wave is useful in localizing ischemic regions of the heart.