Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-02-03
2001-05-22
Getzow, Scott (Department: 3762)
Surgery
Diagnostic testing
Cardiovascular
Reexamination Certificate
active
06236883
ABSTRACT:
Throughout this invention, various publications may be referenced by Arabic numerals in brackets. Disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this invention pertains. Full citations for these publications may be found at the end of the specification.
BACKGROUND OF THE INVENTION
A great deal of information is present in extracellular electrogram morphology about the physiology of conduction of the cardiac impulse (1-4). For this reason, the characteristics of electrograms in reentrant circuits are of interest and have been investigated because they might provide information on mechanisms of slow conduction and block that cause reentry. Particular attention has been paid to the occurrence, location and causes of low amplitude or long duration potentials, double potentials and fractionated electrograms (5-13). In addition, it has been reasoned that if electrogram characteristics in reentrant circuits are specific they might provide an easy and rapid means for locating those circuits without complete activation mapping (12-14). This might facilitate ablation of such circuits with surgical or catheter techniques (12-15). However, specific electrogram characteristics in reentrant circuits have not yet been identified.
The analysis of electrogram morphology in reentrant circuits has only been done for individual complexes. It has not been determined whether there are special and specific dynamic electrogram characteristics, that is, beat-to-beat changes in electrogram shape during the course of tachycardia. We have shown that large dynamic changes in electrogram morphology as quantified by an adaptive template matching technique (16) occur specifically at functional lines of conduction block that bound the central common pathway of figure of eight reentrant circuits (17), in a canine model of ventricular tachycardia. This characteristic provides information about possible mechanisms for block, as well as suggesting that this methodology might be applied to the localization of some ventricular reentrant circuits causing clinical tachycardia. A preliminary report has also been published in abstract form (18).
SUMMARY OF THE INVENTION
This invention provides a method comprising the steps of identifying and localizing reentrant circuits from electrogram features using feature detection and localization (FDL) algorithms.
This invention provides the above method further comprising the steps of:
a) using a contoured array of electrodes arranged in concentric circular patterns to obtain signals from the hearts surface to determine the direction and velocity of the activating wavefront at the catheter location;
b) obtaining and preprocessing analog electrogram signals and multiplexing and storing the signals, in analog or digital form;
c) creating real-time maps and generating other textual information that are displayed on a computer screen, based on reentrant circuit features algorithms.
This invention provides the above method for quantifying dynamic, beat-to-beat changes in electrogram morphology.
As used herein, “dynamic, beat-to-beat changes” means the differences in electrogram shape which occur over the course of two or more cardiac cycles.
This invention provides the above method, wherein signal segments are adaptively matched for best overlap.
This invention provides the above method for quantifying the linear parameter of electrogram shape. One embodiment of the linear parameter is scale. One embodiment of the scale is amplitude. Another embodiment of the scale is duration. Another embodiment of the linear parameter is shift. One embodiment of the shift is phase lag. Another embodiment of the shift is the average baseline.
This invention provides the above method for quantifying the piecewise linear parameter of electrogram shape. In one embodiment the piecewise linear parameter is scale. In one embodiment the scale is amplitude. In another embodiment the scale is duration. In another embodiment the piecewise linear parameter is shift. In one embodiment of the above method, the shift is average baseline. In another embodiment of the above method, the shift is phaselag.
This invention provides a method of quantifying non-linear parameters of electrogram shape. In one embodiment the non-linear parameters are the low pass filter coefficients. In another embodiment the non-linear parameters are the high pass filter coefficients. In another embodiment the non-linear parameters are the notch pass filter coefficients. In another embodiment the non-linear parameters are the bandpass pass filter coefficients. In another embodiment the non-linear parameters are the exponential or other nonlinear coefficients.
This invention provides the above method which uses the mean square error criterion or other criteria for adaptation of weights. In one embodiment, the mean square error measures cycle-to-cycle changes in intrinsic electrogram shape.
This invention provides the above method wherein each electrogram on each cardiac cycle is compared to a reference electrogram or template electrogram. In one embodiment, the reference or template electrogram is obtained from a representative cycle. In another embodiment, the reference or template electrogram is obtained from an average of multiple cycles. In another embodiment, the above method is used to obtain information about changes which occur in electrogram morphology over multiple cardiac cycles from one cardiac cycle to the next.
In one embodiment, the above method uses the differential steepest descent method or other adaptive method to compute the weight update.
In one embodiment, the magnitude and direction for weight adjustment are determined by calculating a derivative or other function of the error based on finite difference changes or other changes in the weighting. In one embodiment, a method is used to minimize the misadjustment of the weight update. In one embodiment, the convergence coefficient is optimized in order to minimize the misadjustment of the weight update. In one embodiment, the convergence coefficient is incremented up or down in order to minimize the mean square error or other error for function during weight update.
In one embodiment, the length of segment is maximized to minimize the misadjustment of the weight update. The maximum length can range of 50 to 1000 milliseconds.
This invention provides the above method wherein the finite difference is optimized to minimize the misadjustment of the weight update. In one embodiment, the finite difference is incremented to minimize the mean square error or other error function during weight update.
In one embodiment of the above method, functional lines of block in reentrant circuits are located by analyzing ATM algorithms. In one embodiment, the data is obtained during sustained monomorphic ventricular tachycardia.
As used herein, “ventricular tachycardia” means an abnormal heart rhythm in which the heart beats more rapidly than normal, which can be caused by a reentrant circuit.
In another embodiment of the above method, functional lines of block in reentrant circuits can be located by analyzing ATM variances or other weight variabilities from data obtained during unsustained monomorphic ventricular tachycardia.
In another embodiment of the above method, functional lines of block in reentrant circuits can be located by analyzing ATM variances or other weight variabilities from data obtained during polymorphic ventricular tachycardia.
In another embodiment of the above method, functional lines of block in reentrant circuits can be located by analyzing ATM variances or other weight variabilities from data obtained during sinus rhythm.
As used herein, “sinus rhythm” means the normal rhythm of the heart in which the regular beating of the heart initiates in a specialized heart cell in a region of the heart called the sinoatrial node.
In another embodiment of the above method, functional lines of block in reentrant circuits can be located by analyzing ATM varia
Ciaccio Edward J.
Wit Andrew L.
Cooper & Dunham LLP
Getzow Scott
The Trustees of Columbia University in the City of New York
White John P.
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