Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-05-14
2001-06-12
Getzow, Scott M. (Department: 3737)
Surgery
Diagnostic testing
Cardiovascular
Reexamination Certificate
active
06246903
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electrocardiography in general and, in particular, to variability evaluation of electrocardiograms.
BACKGROUND OF THE INVENTION
An electrocardiogram, or “ECG”, is a graphical record of the electric potentials produced by activity of the heart. In the same way that heart activity is cyclical, the electrical potentials produced by activity of the heart are also cyclical, and measurement thereof has resulted in the well known characteristic ECG waveform. It is known that the portions of this waveform correspond to different events which together form the cyclical activity of the heart, and the known, basic P, Q, R, S, T, U waves are so-called, due to six commonly identified transition points on an ECG waveform; portions of the waveform bounded by these points being understood as representing activities of specific intra-heart organs. By way of example, the QRS portion (i.e. that portion of the waveform defined between the QRS nodes), known also as the QRS complex, occurs at the time that the ventricles of the heart contract, or “systole.” The so-called “T wave” is caused by repolarization of the electrical system following contraction, or “diastole.” It is understood that changes observed in any of these waves can be used for various cardio-diagnostic purposes, by way of example, the S-T elevation is taken as one of the classic signs of heart infarcation.
It is, in fact, known that current interpretation of the electrocardiogram is very limited, due to the fact that the heart is known to be a very complex organ, and each operating cycle thereof is not limited merely to a small number of events, such as the electrocardiogram might indicate. The occurrence of this very large number of heart events is well known, and, by way of example, is discussed in a book entitled
CLINICAL SCALAR ELECTROCARDIOGRAPHY
; by Lipman, Massie and Kleiger; and bearing Library of Congress Catalog Card Number 72-188577.
It is further known to extract useful information concerning certain heart organ functions by assessing variability of data contained therein. An indication of the state of the art is provided by U.S. Pat. No. 5,188,116 and 5,419,338.
The '116 publication, entitled “Electrocardiographic Method and Device,” is directed to method and apparatus for detecting heart disease from an electrocardiogram (ECG). The method comprises the steps of acquiring the ECG signals, correcting for signal variability caused by breathing and calculating the level of remaining variability due to myocardial function. The apparatus comprises a signal input system, a storage system, a microprocessor and an output system. The microprocessor has program logic for processing signal data in accordance with the method
The '338 publication, entitled “Autonomic Nervous System Testing by Bi-Variate Spectral Analysis of Heart Period and QT Interval Variability,” discloses apparatus and a method for testing the autonomic nervous system of a mammal through bi-variate analysis of heart Period (RR) and QT interval variability obtained through data processing of electrocardiographic data. The method and apparatus enable both the parasympathetic and sympathetic controls on the heart to be evaluated for imbalances therebetween, which may indicate a predisposition for sudden cardiac death.
Neither of the above methods provides an overall approach which enables the determination of the overall state of the heart of a subject relative to a norm, the mapping of various heart functions, and the determination of a trend, such that even if a subject is seen to have a serious heart condition, it is possible to establish whether his condition is improving or deteriorating.
SUMMARY OF THE INVENTION
It is thus an aim of the present invention to provide a novel method and a device for the measurement of heart activity and in-depth quantitative prognostic evaluation of the results of the ECG. The method and device are based on high resolution sampling of ECG readings, accurate establishment of multiple characteristic points, statistical evaluation of the intervals, and mapping of the evaluated data.
There is thus provided, in accordance with a preferred embodiment of the invention, a method of providing an indication of the physiological state of the heart of a mammal by the steps of detecting periodic activity of internal heart organs in a sequence of heart cycles; observing a predetermined physical quantity characteristic of a selected activity; evaluating predetermined statistical parameters of the predetermined physical quantity for a selected number of the sequence of heart cycles; and comparing the evaluated statistical parameters with reference values thereby to provide an indication of the state of the selected activity.
Additionally in accordance with a preferred embodiment of the invention, the step of observing includes the step of measuring the time period taken by each activity, and the step of evaluating includes the step of evaluating predetermined statistical parameters of the time periods of a selected activity in a selected number of the sequence of heart cycles.
Further in accordance with a preferred embodiment of the invention the step of evaluating includes evaluating a first statistical parameter indicating the state of the selected activity at the time of performing the step of detecting, and the step of comparing includes comparing the evaluated first parameter with a reference range, and further includes the step of determining a relationship between the evaluated first statistical parameter and the reference range, thereby to also determine the physiological state of the mammal at the time of performing the step of detecting.
Additionally in accordance with a preferred embodiment of the invention, the step of evaluating also includes evaluating a second statistical parameter indicating a trend in the state of the selected activity, and the step of comparing also includes comparing the evaluated second parameter with a reference range, and further includes the step of determining a relationship between the evaluated second statistical parameter and the reference range, thereby to also determine the trend in the state of the selected activity.
Further in accordance with a preferred embodiment of the invention the step of comparing further includes the step of providing a visual reference system which includes first visual indications corresponding to the reference range, including a plurality of reference axes, each corresponding to a different predetermined heart activity, and the step of determining a relationship includes the sub-steps of:
providing on the reference axes second visual indications corresponding to values of a predetermined statistical quantity for each heart activity; and visually comparing the second visual indications with the first visual indications, thereby to determine a relationship therebetween.
Additionally in accordance with a preferred embodiment of the invention, the reference system is a multi-axis reference system which has a plurality of axes radiating from an origin, wherein each axis defines a scale on which is indicated a range of possible values of the predetermined statistical quantities corresponding for a predetermined heart activity, and wherein the first visual indications of the reference system are closed-shape line markings provided concentrically about the origin, thereby to define two or more reference regions, wherein visual indications within a first region indicate a first state of health of the heart of the mammal, and visual indications within a second region indicate a second state of health of the heart of the mammal, different from the first state of health,
and the step of comparing the second visual indications with the first visual indications includes determining where the second visual indications fall relative to the reference regions, thereby to visually determine the state of health of the heart of the mammal.
Further in accordance with a preferred embodiment of the invention the step of prov
Cardiosol Ltd.
Fitch Even Tabin & Flannery
Getzow Scott M.
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