Deriving p-waves in electrocardiac signals having superimposed complexes
Abstract
An electrophysiology system that includes a processor configured to derive a hidden P-wave signal on a T wave within a premature atrial contraction ("PAC") beat, characterized in that the processor includes means of executable codes for: (a) select a QRS-T segment of a reference ECG signal; (b) allow a user to mark an initial point and an endpoint of the selected segment of the reference ECG signal; (c) define a reference pattern as a waveform segment between the marked start and end points of the selected segment of the reference ECG signal; (d) acquire the PAC beat in the signal processing unit from multiple conductors; and (e) process the PAC beat to derive the p-wave signal.

Term
Term ended
Projected expiry passed 7 November 2021, 4.9 years ago.
- Priority
- Filed
- Published
- Projected expiry
- Today
25 claims: 2 independent, 23 dependent
- 1ES 2 329 338 T3 REIVINDICACIONES 1. Un sistema de electrofisiología que incluye un procesador configurado para derivar una señal de onda-p oculta en una onda T dentro de un latido de contracción atrial prematura (“PAC”), caracterizado porque el procesador incluye medios de códigos ejecutables para:(a) seleccionar un segmento QRS-T de una señal ECG de referencia;(b) permitir a un usuario marcar un punto inicial y un punto final del segmento seleccionado de la señal ECG de referencia;(c) definir un patrón de referencia como un segmento en forma de onda entre los puntos inicial y final marcados del segmento seleccionado de la señal ECG de referencia;(d) adquirir el latido PAC en la unidad de procesamiento de señales desde múltiples conductores;y (e) procesar el latido PAC para derivar la señal de la onda-p.
- 2El sistema de la reivindicación 1, en el que el procesador comprende medios para sustraer el patrón de referencia desde un segmento predeterminado del latido PAC.
- 3El sistema de la reivindicación 1, en el que la señal ECG de referencia es un latido individual.
- 4El sistema de la reivindicación 3, en el que la señal ECG de referencia se obtiene a partir de un conductor intracardiaco.
- 5El sistema de la reivindicación 1, en el que la señal ECG de referencia es una señal derivada desde un promedio de latidos múltiples.
- 6El sistema de la reivindicación 1, en el que la señal ECG de referencia es un latido que precede inmediatamente al latido PAC.
- 7El sistema de las reivindicaciones 1 ó 6, en el que el procesador incluye, además, medios para permitir al usuario seleccionar como una señal ECG de referencia alternativa un segmento que precede o que sigue inmediatamente al segmento QRS-T.
- 8El sistema de la reivindicación 1, en el que el procesador incluye, además, medios para sincronizar el patrón de referencia y el latido PAC alineando sus segmentos en forma de onda respectivos.
- 9El sistema de la reivindicación 8, en el que la alineación se realiza utilizando un cálculo de coeficiente de correlación sobre el latido PAC adquirido para identificar el mejor ajuste entre los segmentos respectivos de la forma de la onda.
- 10El sistema de la reivindicación 8, en el que los segmentos respectivos de la forma de la onda son los complejos QRS del patrón de referencia y el latido PAC.
- 11El sistema de la reivindicación 10, en el que la alineación se realiza utilizando un cálculo de coeficiente de correlación sobre el latido PAC para identificar el mejor ajuste entre los complejos QRS del patrón de referencia y el latido PAC.
- 12El sistema de la reivindicación 9, en el que el procesador incluye, además, medios para permitir al usuario desviar la alineación, provocando de esta manera un cambio en el cálculo del coeficiente de correlación.
- 13El sistema de la reivindicación 9, en el que el procesador incluye, además, medios para permitir al usuario desviar el patrón de referencia hacia un segmento de la forma de la onda entre puntos inicial y final correspondientes de un latido diferente, provocando de esta manera un cambio en el cálculo del coeficiente de correlación.
- 14El sistema de la reivindicación 1, en el que el procesador incluye, además, medios para:adquirir y procesar repetidas veces al menos dos latidos PAC diferentes para derivar al menos dos señales de onda-p;y para comparar las señales de onda-p derivadas entre sí. ES 2 329 338 T3
- 15El sistema de la reivindicación 14, en el que los medios para comparación realizan un análisis de la forma de la onda de correlación cruzada.
- 16El sistema de la reivindicación 14, en el que el procesador incluye, además, medios para indicar selectivamente en un dispositivo de salida una calidad de una coincidencia como una función de la etapa de comparación para proporcionar de esta manera un indicador de si las ondas-p derivadas tienen o no el mismo origen focal.
- 17El sistema de la reivindicación 1, en el que el procesador incluye, además, medios para comparar la onda-p derivada con una biblioteca de ondas-p de origen focal conocido, y predecir el sitio más probable del origen como una función de la comparación.
- 18El sistema de la reivindicación 1, en el que la onda-p derivada es una onda-p espontánea derivada, y el procesador incluye, además, medios para adquirir y procesar repetidas veces la señal PAC mientras un catéter de proyección sincronizada está siendo maniobrado dentro o adyacente al atrio y el corazón está siendo sincronizado, para derivar una señal de onda-p sincronizada, y comparar la señal de onda-p sincronizada con una señal de onda-p espontánea, derivada libre de sincronización del corazón.
- 19El sistema de la reivindicación 1, en el que el procesador comprende, además, medios para determinar un valor integral de la zona de la señal de onda-p derivada.
- 20El sistema de la reivindicación 19, en el que el procesador incluye, además, medios para normalizar el valor integral sobre una longitud de la señal de onda-p derivada.
- 21El sistema de la reivindicación 20, en el que los puntos inicial y final marcados definen un segmento QRS de la señal ECG de referencia, y el procesador incluye, además, medios para medir el residuo QRS de la señal de ondap derivada para proporcionar un indicador de la calidad de la alineación entre el segmento QRS del latido PAC y un segmento WRS del patrón de referencia.
- 22El sistema de la reivindicación 21, en el que los medios de procesamiento comprenden medios para sustraer el patrón de referencia desde el segmento QRS del latido PAC y en el que el residuo QRS es un valor integral computado después de la etapa de procesamiento.
- 23El sistema de la reivindicación 1, en el que el procesador incluye medios para:adquirir y procesar repetidas veces latios PAC múltiples;calcular para cada latido PAC el valor integral del segmento QRS del patrón de referencia y el valor integral del latido PAC, determinar cualquier cambio en el porcentaje del valor punta absoluto de los valores integrales entre el patrón de referencia y el latido PAC, de manera que se identifica cualquier desviación de la línea de base.
- 24El sistema de una cualquiera de las reivindicaciones anteriores, que incluye, además:(a) una unidad de detección de señales, en la que el procesador está conectado para recibir señales electrocardiacas desde la unidad de detección de señales y configurada para procesar las señales electrocardiacas para derivar la señal de la onda-p a partir del latido PAC;y (b) un dispositivo de salida para presentar la señal de onda-p derivada.
- 25El sistema de la reivindicación 24, que comprende, además, un dispositivo de almacenamiento para almacenar las señales electrocardiacas procesadas.
Independent claims25
92 paragraphs in 5 sections, as filed
ES 2 329 338 T3
DESCRIPTION
System for processing electrocardiac signals that have overlapping complexes.
Field of the invention
This invention relates to a system for processing electrical signals obtained from the heart and, more particularly, to a system for processing electrocardiac signals having complex sub-components superimposed to allow tracking of native, synchronized and derived beat signals.
Background of the invention
Certain cardiac arrhythmias are triggered or initiated from a site in the heart tissue other than the sinusoidal node. These arrhythmias are generally classified as "focal" in nature. Treatment of focal arrhythmias generally involves locating the arrhythmogenic site and ablating it. One method of regional localization of the focal site is the use of a diagnostic 12-Lead ECG. The 12 Lead can be used in combination with synchronization via a roaming intracardiac catheter to synchronize the map of the heart. The theoretical basis for this method assumes that the synchronized 12 lead ECG will appear identical to the unsynchronized ECG if the cycle length (i.e., synchronized heart rate) and the synchronization site match the unsynchronized heart rate and focal site of source.
A problem with this method (in current practice) is the subjectivity involved in the visual comparison of an unsynchronized 12 Lead ECG and a synchronized 12 Lead ECG.
A second problem is the time-consuming nature of the procedure, in which a spontaneous ectopic beat is typically recorded and printed on paper. A roving projection catheter is positioned at a likely site of ectopia, synchronization is initiated, a recording is made, an impression is generated, and a visual comparison is made by aligning the impressions of the spontaneous and synchronized beats one over the other. This process is repeated in an iterative manner until the clinician determines that a good match has been found between the spontaneous ectopic beat and the synchronized beat.
A third problem arises when multiple arrhythmogenic foci are present and each focus produces a variant on the 12 Lead ECG. Improved discrimination between these foci would be advantageous during synchronized projection as well as during other EP procedures. (Ref.- Throne RD, Jenkins JM, Winston SA, et al. "Use of tachycardia templates for recognition of recurrent monomorphic VR." Comp. Cardiology 1989: 171-174.
A fourth problem involves the overlap of components of the P-wave and the T-wave of the ECG. The electrocardiogram typically includes an initial pulse, called a P-wave, emanating from the atrium, followed by what is called the QRS complex, emanating from the ventricles, which is followed by a T-wave resulting from the regularization of the ventricles (figure 1). So one heartbeat starts with the P-wave and ends with the T-wave, the next heartbeat starts with another P-wave.
The P-wave can be a valuable tool used by physicians to diagnose the condition of the heart. Therefore, physicians often monitor an electrocardiogram (ECG) of the heart to aid in the diagnosis of atrial and ventricular arrhythmias. This can be done in a number of ways, such as monitoring the 12 Lead (surface) ECG in combination with observing the bioelectrical activity recorded on intracardiac electrodes carried by a transthoracic catheter.
In some focal arrhythmias, the atrial heart tissue begins to beat very rapidly as the focal origin moves from the sinusoidal node to an ectopic site. Sometimes this higher heart rate is sustained for three or more beats and is called tachycardia. Other times, the higher rhythm is intermittent and can be as short as a heart beat. In any case, the first beat of the atrial arrhythmia is usually initiated by what is called a Premature Atrial Contraction (“PAC”) which can result in the P-wave of a successive heart beat that overlaps with a T-wave of the preceding beat (Figure 2). This is not only a physiologically compromised state for the heart, but the physician can no longer use the P-wave to diagnose the heart because it is obscured by the T-wave.
Accordingly, it will be apparent that there continues to be a need for a method that allows a physician to synchronize projection more efficiently and, furthermore, to monitor the P-wave of a patient's heartbeat, even when the P-wave overlaps. with a preceding T-wave. The present invention meets these needs.
And although the subtraction of the T-wave is a useful method in electrophysiology procedures to unmask the morphology of the P-wave ECG of a PAC through the subtraction of a QRS-T pattern of a PAC, the deviation of the line ECO base caused by breathing or body movement can cause certain variations in the results of the T-wave subtraction. Therefore, there continues to be a further need in the art to quantitatively measure the quality of T-wave subtraction results, among other reasons to monitor variations in respiration on T-wave subtraction. The present invention also satisfies this need.
ES 2 329 338 T3
US Patent No. 6,840,038, issued to Xue, describes a method and apparatus for averaging and analyzing high resolution P-wave signals. Xue isolates the signals from the P-wave by replacing the QRST portion of the signal with a straight line, thus acting on the assumption that the P portion is not superimposed on QRST portions. US Patent No. 5,772,604 issued to Langberg teaches isolating atrial fibrillatory baseline signals by subtracting a QrSt pattern. In this method, Premature Atrial Contraction (“PAC”) is not recognized or isolated, since there are no PAC beats associated with arrhythmia, in which there are no P waves.
Article by MLYNASH et al .: Automated QRST subtraction algorithm for analysis of T wave obscured ectopic atrial beats, BMES / EMBS CONFERENCE OF THE FIRST JOINT ATLANTA, GA, USA October 13-16, 1999, Vol. 1, pages 265 XP010357259 , Piscataway. NJ, USA, IEEE describes an electrophysiology system that includes a processor configured to derive a p-wave signal hidden in a T wave within a premature atrial contraction ("PAC") beat, wherein the processor includes means of executable codes for:
selecting a reference ECG signal QRS-T segment;
acquiring the PAC beat in the signal processing unit from multiple leads; and processing the PAC beat to derive the signal from the p-wave.
Summary and objects of the invention
In accordance with the present invention, an electrophysiology system is provided that includes a processor configured to derive a p-wave signal hidden in a T wave within a premature atrial contraction ("PAC") beat, characterized in that the processor includes executable code means for:
(a) selecting a QRS-T segment of a reference ECG signal;
(b) allowing a user to mark a start point and an end point of the selected segment of the reference ECG signal;
(c) defining a reference standard as a waveform segment between the marked start and end points of the selected segment of the reference ECG signal;
(d) acquiring the PAC beat in the signal processing unit from multiple leads; and (e) processing the PAC beat to derive the signal from the p-wave.
The present invention provides a physician assistant with a method of objectively and efficiently performing real-time synchronized projection and other cardiac analyzes, through the processing of incoming electrical signals representing cardiac activity to display a derived P-wave without overlap with a preceding T-wave during a CAP, and to allow the physician assistant to objectively compare derived P-waves to determine whether they emanate from the same focus. As a direct consequence of the cardiac signal processing of the present invention, otherwise masked signals and correlations between heartbeats and heartbeat segments are identified through calculations on acquired signals and / or new signal leads. The physician assistant can be guided through visual aids such as bar graphs or overlapping cardiac signals of the quality of the signal matches. These signal coincidences can aid in the diagnosis of a patient and in the effectiveness of an ongoing treatment, for example, an ablation procedure.
Due to the timing and amplitude relationships between beats in a heart, the possibility exists that individual waveforms can be obscured or hidden. If a singular, unadulterated sub-component waveform is identified, and if this sub-component has similar time-synchronization characteristics that allow it to synchronize with the composite waveform, then a subtraction process can be performed to derive in this way the other sub-component waveform (s). Subcomponent waveforms, whether derived, native state, or synchro-induced, can be quantitatively compared with each other using correlation analysis. This analysis can be performed retrospectively or in real state.
The present invention provides programmed systems and machines, which allow superior signal processing over prior art electrophysiology signal processors and can achieve estrus using a standard 12 lead ECG.
One embodiment provides a system for tracking ectopic beats comprising a signal detection unit, a signal processor, and an output device. The signal detection unit is configured to capture a first ECG signal. The signal processor is connected to receive the first ECG signal from the signal detection unit and is configured to allow a user to mark a point
ES 2 329 338 T3 initial and an end point of the first ECG signal for use in defining a waveform segment as a reference standard, to acquire data from multiple leads, and to identify the best fit between the pattern of reference and data acquired using a correlation coefficient calculation. The output device has the best fit identified.
Another embodiment provides a system for deriving a p-wave signal from a premature atrial contraction ("PAC") beat, comprising a signal detection unit, a signal processor, and an output device. The signal processor is connected to receive electrocardiac signals from the signal detection unit and is configured to process the electrocardiac signals to derive the p-wave signal from the PAC beat. The output device displays the derived p-wave signal.
In a particular embodiment of the above system, the processor is configured to execute the steps of (a) selecting a QRS-T segment of a reference ECG signal; (b) allowing a user to mark a start point and an end point of the selected segment of the reference ECG signal; (c) defining a reference standard as a waveform segment between the marked start and end points of the selected segment of the reference ECG signal; (d) acquiring the PAC beat in the signal processing unit from multiple leads (preferably with no more than 12 leads); and (e) processing the PAC beat to derive the signal from the p-wave.
Another embodiment provides an electrophysiology computer system that includes a processor that is configured to derive a hidden p-wave signal within a premature atrial contraction ("PAC") beat. The processor executes the steps of (a) selecting a QRS-T segment of a reference ECG signal; (b) allowing a user to mark a start point and an end point of the selected segment of the reference ECG signal; (c) defining a reference standard as a waveform segment between the marked start and end points of the selected segment of the reference ECG signal; (d) acquiring the PAC beat in the signal processing unit from multiple leads; and (e) processing the PAC beat to derive the signal from the p-wave.
In a particular embodiment of the above system, the processor uses a calculation of the correlation coefficient to perform a subtraction of the reference pattern from a predetermined segment of the PAC beat. In more particular embodiments, the processor is configured to compare p-waves derived from multiple beats with each other, to indicate or lower a common focal origin among several derived p-waves to predict the most likely site of the origin of a focus. using a library (preferably 12 leads) of p-waves of known focal origin, to derive synchronized p-waves for comparison with spontaneous p-waves, to determine an integral value of the QRS area of a derived p-wave signal, to normalize integral values above a length of the derived p-wave signal, to process the QRS segment of a beat separately to arrive at other determinations that refer to the data of the heartbeat, and to make combinations of the above.
Another embodiment provides an electrophysiology computer system including a processor that is configured to execute steps in substantially the same way as the processor deriving an ondap shape from a PAC beat, but it is more generally configured to derive an unsynchronized sub-component from a first heartbeat signal having a composite waveform that includes a synchronous sub-component that overlaps the non-synchronous sub-component. The processor executes the steps of selecting a synchronous sub-component of a second heartbeat signal, which corresponds to the synchronous sub-component of the first heartbeat signal; allow a user to mark a start point and an end point of the selected synchronous segment; defining a reference standard as a waveform segment between the marked start and end points of the selected synchronous sub-component; acquiring the composite waveform of the first heartbeat signal in the signal processing unit from multiple leads; and processing the beat of the composite waveform to derive the non-synchronous sub-component.
Also described is a method that is not part of the claimed invention for tracking ectopic beats through pattern matching, which includes the steps of:
(a) capturing a first ECG signal in a signal processing unit; (b) allowing a user to mark the start point and end point of the first captured ECG signal; (c) defining a reference standard as a segment of the waveform between the marked start point and end point of the first ECG signal; (d) acquiring data in the signal processing unit; and (e) using a correlation coefficient calculation on the acquired data to identify the best fit between the reference standard and the acquired data.
In addition, a method that is not part of the claimed invention for deriving a p-wave signal from a premature atrial contraction ("PAC") beat is also described, which can assist a person in the diagnosis of a heart. . This method includes the steps of (a) selecting a QRS-T segment from a reference ECG signal; (b) allowing a user to mark a start point and an end point of the selected segment of the reference ECG signal; (c) defining a reference standard as a waveform segment between the marked start and end points of the selected segment of the reference ECG signal; (d) acquiring the PAC beat in the signal processing unit from multiple leads; and (e) processing the PAC beat to derive the signal from the p-wave.
In a particular example of the above methods, the PAC beat is processed using a correlation coefficient calculation to perform a subtraction of the reference pattern from a predetermined segment of the beat.
ES 2 329 338 T3
PAC. In addition, the above methods may include the additional steps of: comparing p-waves derived from multiple beats with each other; indicate or less a common focal origin between several derived p-waves; predicting the most probable site of origin of a focus using a library (preferably 12 leads) of p-waves of known focal origin; I will derive the synchronized p-waves for comparison with spontaneous p-waves; determining an integral value of the QRS area of a derived p-wave signal; normalizing the integral values over a length of the derived p-wave signal; processing the QRS segment of a beat separately to arrive at other determinations related to the heart beat data; and perform combinations of the previous stages.
Other methods include the determination of integrals that refer to a section of the QRS-T segment and the processing of these integrals. A QRS segment integral can be used as a measure of QRS residual, which is an indicator of the quality of alignment or synchronization between the QRS pattern and the QRS PAC. In addition, the deviation from the baseline can be monitored as a percentage change from the absolute peak (integral) value between the standard and the CAP. These methods are implemented by appropriately configured computer processors.
Still another method works in substantially the same way as when deriving a p-wave from a PAC beat, but more generally includes selecting the synchronous sub-component of the heartbeat signal, allowing a user to mark a starting point, and an end point of the selected synchronous sub-component, define a reference pattern as a segment of the waveform between the marked start and end points of the selected synchronous sub-component, acquiring the composite waveform in the signal processing unit from multiple leads, and processing the beat of the composite waveform to derive the non-synchronous sub-component.
In a method that is not part of the claimed invention, a pattern optimization method that dynamically employs different patterns can be used. The QRS beats that precede or follow a CAP can be selected manually or by the addition of a programmed machine selecting and setting a new pattern for use in subsequent calculations. The method is implemented by appropriately configured computer processors.
Other features and advantages of the invention can be more clearly understood from the following detailed description of exemplary embodiments and from the accompanying drawing figures.
Description of the figures in the drawings
Figure 1 is a schematic diagram of a normal heart beat.
Figure 2 is a schematic diagram of a premature atrial contraction (PAC).
Figure 3 is a schematic diagram of T-wave subtraction.
Figure 4 is a block diagram of a system programmed to practice a method in accordance with a preferred embodiment of the present invention.
Figure 5 shows a flow chart showing the process for adapting the pattern according to the preferred embodiment.
Fig. 6 is a flow chart showing the process for T-wave subtraction according to the preferred embodiment.
Figure 7 is a representative computer display interface for T-wave subtraction that can be viewed by an operator.
Figure 8 is a representative computer screen interface for tailoring the pattern that can be displayed to an operator.
Figure 9 illustrates a methodology for determining the integrals of a section of the QRS-T segment after the subtraction process.
Detailed description of the preferred embodiments
In order to aid understanding of the methods that can be practiced in accordance with preferred embodiments of the present invention, various pertinent aspects are described below in the respective headings.
Pattern Match / Synchronized Projection
Any recorded ECG waveform can be used as a reference for comparison with another recorded ECG waveform or with a real-time ECG waveform. The comparison is made in a process of
ES 2 329 338 T3 two stages, in which a reference pattern is first selected by the user to describe the beginning and end of a segment of the ECG waveform that can be used as a comparison pattern. The user then selects pre-recorded data or from a real-time data stream. A properly configured computer processor can find the best match against the reference standard over the specified region, or in the case of real-time analysis, can find the best updated match over a defined period of time, for example every second. The "best match" criteria uses a correlation coefficient calculation across all twelve ECG leads and finds the best alignment. A visual display showing the aligned reference beat (pattern) superimposed on the beat being analyzed gives the user information regarding the accuracy of the match. A correlation coefficient calculated for each ECG lead gives a quantitative indicator of the match. A composite average is also calculated and plotted in a single enhanced color bar chart indicator, which is especially useful when you are matching the pattern in real time. The composite average can be updated as a moving average over a selected number of beats.
Pattern matching can be used to compare two spontaneous beats, or it can be used to synchronize the projection, that is, to compare a synchronized beat with a spontaneous beat. A Region of Interest Indicator (ROI) can be manipulated by the user to exclude certain portions of the waveform from analysis. This is useful during synchronized projection where synchronization artifacts on surface conductors can be excluded from the analysis region. The ROI indicator can also be used to specify a preference for a T-wave or wave match, as they can sometimes be morphologically very similar.
T-wave subtraction
In one example, which is not part of the claimed invention, a method is described whereby an ECG having a P-wave and an overlapping T-wave is processed to eliminate the T-wave and thus visualize the P-wave without overlap so that a doctor can look at the P wave when making a heart diagnosis.
See Figure 1, which depicts a three-beat ECG, in which distinctive P and T waves can be identified. Figure 2 shows a rhythm in which the P-wave from the third beat (P ') arrives early and is obscured by the T-wave from the second beat. This results in what is called a full P over T. and is referred to as a QRS-TP 'in the figure.
In general, according to the method, the QRS-T segment of a beat lacking a PAVC is selected as a pattern. This pattern is subtracted from the QRS-TP 'signal in the PAC to be studied, providing the P-wave. The QRS-T signal used as the pattern can be from a single beat or it can be derived from an average of multiple beats. The QRS-T (or mean) signal used as the pattern is selected so that the preceding QRS-QRS interval is equal to (or approximately equal to) the QRS-QRS interval immediately preceding the QRS-TP 'signal to be studied. Preferably, the beat immediately preceding the CAP can be used for the selected QRS-T pattern, since the cycle length and hemodynamic conditions of this beat are closest to those of the next beat containing the CAP and the complete P over T. (See Figures 2 and 3).
The QRS complex is used as a means to synchronize and align the QRS-T pattern and the PAC beat for subtraction. The alignment is automated by the algorithm for best match based on the composite correlation coefficient through the 12 Lead CECG. The physician assistant has the option of shifting the pattern match left or right on a sample-by-sample basis with the resulting composite correlation coefficient updated at each new position. The physician assistant has the option of selecting the previous or next QRS-T segment as the reference standard. The software will automatically locate the previous or next beat based on the current reference pattern and using the corresponding QTS-T segment of that beat as the new reference pattern in the derived O-wave calculation.
Different screen views showing the derived P-wave, alone or superimposed on the original PAC beat or the reference pattern are available as an aid to the physician assistant.
P-waves that have been derived using the T-wave subtraction method can also be subjected to signal processing to eliminate unwanted artifacts caused by respiration or noise.
3. Derived P-Wave Pattern Matching
Once a derived P-wave has been identified from the tachycardia or premature atrial beat (CAP), this derived P-wave can be compared to a previously captured reference standard.
3rd. More specifically, one or more spontaneous P-waves can be identified using the subtraction method described above and compared to another using waveform correlation analysis. This can be used to determine if the spontaneous P-waves have the same focal origin. This can be done in real time or in review from logged data.
ES 2 329 338 T3
3b. In addition, one or more derived spontaneous P-waves can be identified and compared to a library of P-waves of known focal origin to predict the most likely site of origin.
3c. In addition, once the derived spontaneous P-wave has been identified by the T-wave subtraction method, as described above, then the physician assistant can initiate the atrial synchronization projection according to the Match-with-the method. synchronized pattern / projection, also described above. The roving synchronization projection catheter is maneuvered within the atrium (or adjacent vessels, such as the pulmonary veins) until the derived synchronized P-wave is nearly identical to the derived spontaneous P-wave. This comparison of derived P-waves can be performed on recorded data or in real time.
More generally, two or more waveforms X, Y, ..., can form a composite waveform that, due to time synchronization and amplitude relationships, causes the individual waveforms to be obscured or hidden. . The composite waveform includes a synchronous sub-component that overlaps a non-synchronous sub-component. If a singular, unadulterated subcomponent waveform can be identified (for example, X or Y), and if it has similar time-synchronization characteristics that allow it to be synchronized with the composite waveform (i.e., that this identified sub-component is the synchronous sub-component), then it can be subtracted from the composite waveform to derive the other sub-component waveform (s) (i.e., the (the) non-synchronous sub-component (s). The sub-component waveforms, whether derived, native, or synchronized-induced, can be quantitatively compared with each other using correlation analysis. This analysis can be done retrospectively or in real time. One skilled in the art will appreciate that a number of algorithms can be used to compare waveform, including, but not limited to, binary area and integral methods; Either of these methods can help the purpose of aligning synchronous components of composite waveforms and / or comparing derived results.
A method that is not part of the claimed invention in accordance with that more general teaching is generally carried out as described above. Specifically, this method acts in substantially the same way as when deriving a p-wave from a PAC beat, but more generally includes selecting the synchronous subcomponent of the heartbeat signal, allowing a user to mark a starting point, and an end point of the selected synchronous sub-component, define a reference pattern as a segment of the waveform between the marked start and end points of the selected synchronous sub-component, acquiring the composite waveform in the signal processing unit from multiple conductors, and processing the composite waveform to derive the non-synchronous sub-component.
Referring now to the drawings, and particularly to Figure 4, there is shown a system 10 for receiving and processing electrical signals in accordance with an illustrative embodiment of the present invention. In an illustrative embodiment, system 10 includes a signal detection unit 12, which can take different forms, such as a standard 12 lead ECG, intracardiac lead, or a combination thereof. The signal detection unit is electrically connected to a signal processing device 14, which receives the detected signals from the unit 12 and processes the signals, as described in more detail below. The signal processing device ("signal processor" or "processor") 14 is preferably connected to a suitable display 16 which will present the processed signals to a physician or other interested person. Information can be stored and recalled from memory device 18. Preferably, signal processing device 14 and display 16 comprise the EP LabSystem (trademark) of CR Bard, Inc., Murria Hill, New Jersey, or Similary. The EP LabSystem (trademark) supports a variety of data collection and processing functions that are standard in electrophysiology procedures, and you can have your hardware (i.e. processor 14) configured to implement the subtraction and bypass methods listed above, for example, via software (eg modules, procedures, functions or objects) or firmware. Processor 14 communicates with memory or storage 18 that configures the processor to implement the above subtraction and bypass methods (as well as the comprehensive techniques described above).
In an illustrative example, the special features of the system of the present invention are implemented, in part, by a processor using program information stored in a memory of signal processing device 14. Processor 14 can access one or more files, as necessary, to implement the required functions, as described in more detail in connection with Figures 5 and 6.
Referring now to Figure 5, the operation of signal processing device 14 of the present invention is described in conjunction with the above structural description of system 10. As illustrated in Figure 5, the process begins when a physician wishes to create a reference standard, and this is done by capturing a reference ECG signal, as indicated in step 5032. Preferably, the reference ECG signal is captured using a standard 12-lead device and one or more intracardiac leads. As explained above in connection with Figure 2, the components of the QRS-T signal of a beat that does not show P-wave on T-wave are selected as a pattern and it is this set of components of electrocardiac signals that is captured in step 502. Such a beat can be captured in sinusoidal rhythm or during a focal arrhythmia, such as a tachycardia. In addition, it is contemplated that the reference pattern results from signals captured, or on the surface, from intracardiac conductors that may be placed in a variety of locations within the
ES 2 329 338 T3 heart or a combination of surface signals and intracardiac conductors. The QRS-T signal that is used as the pattern can be captured from an average of multiple heartbeats.
In step 504, the start and end points of the reference standard are marked by the physician using an interface with the signal processing unit 14. The marked points define the wave segment of the ECG wave that should be used as a pattern. comparison.
At step 506, the physician selects whether recorded data or real-time data should be used in the pattern match analysis. (This step can be performed at any time prior to the waveform match analysis in step 508, for example, prior to performing steps 502 and 504). If recorded data is to be used in the pattern match analysis, then a specific region of previously recorded data is provided to the signal processing unit for comparison with the reference standard. On the other hand, if real-time data is to be used in pattern match analysis, it reproports a stream of data from ECG leads to signal processing unit 14 for a defined period of time for comparison with the reference standard.
At step 508, signal processor 14 finds the "best match", in other words, the best alignment between the selected region or selected time period and the reference standard.
At step 510, the screen 16 is updated to indicate to the physician (or others) the result of the pattern match. Results can be qualitatively displayed as superimposed ECG waveform signals, namely the reference beat (pattern) superimposed on the analyzed beat to show the degree of alignment between them.
In step 512 a test is performed to determine if the user had selected real-time processing in step 506. If so, then the flow loops return to step 508 to perform the pattern match analysis again and to update the screen accordingly. Otherwise, if previously recorded segments are being analyzed, the user is given the option to save the analysis (as tested in step 514), and the correlation analysis is saved, as indicated in step 516. The analyzes in real time they can also be saved, if desired.
Referring now to Figure 6, the operation of signal processing device 14 of the present invention is described in conjunction with the above structural description of system 10. As illustrated in Figure 6, the process begins at step 602 when A clinician captures a PAC and wants to subtract a QRS-T reference pattern from the PAC. The QRS-T reference pattern is marked by the physician at step 604 (as described above) and a region that includes the PAC is selected by the physician at step 606 for analysis. The QRS portion of the reference pattern is aligned for optical fit with the QRS complex immediately preceding the CAP at step 608. When the best fit has been found, the processor 14 subtracts the QRS-T reference pattern from the QRS-segment. TP 'of the CAP at step 610.
The difference is the derived P-wave that is output to screen 16 in step 612. This is illustrated on the computer screen shown in Figure 7, in which the leftmost window represents the selected QRST reference pattern. between two vertical lines (a dashed line in front of the second mark 14 at the top (highlighted by an arrow), and a second solid line just after the second mark 14). The rightmost window shows the original PAC waveform with the derived P-wave superimposed over the top of the portion of the ECG that occurs in the first 15 seconds. The derived and superimposed P-wave appears as a second graph superimposed on the ECG signals. Visual aids can be provided to automatically align and superimpose waveforms for visual comparison on a computer screen or printout.
Figure 8 illustrates an exemplary screen for pattern matching (without subtraction) that can be viewed by an operator. The leftmost window represents markers that signify the presence and use of the reference standard; the reference pattern begins at the leftmost vertical line (highlighted by the arrow) and ends at the second vertical line. In this example, the reference pattern marks the beginning and end of a P-wave; however, any waveform segment can be used if the region of interest has been marked for use as a pattern. The larger display advantage to the right shows the correlation value for each channel of the 12 Lead ECO compared to the reference standard. The rightmost bar graph is inactive in this example, because the analysis region is taken from recorded data rather than real-time data collected during a medical procedure.
The data can be saved, printed, or both, if desired, in response to a user input to do so, as tested in step 614 and executed in step 616.
From the foregoing, it will be apparent to those skilled in the art that the present invention provides a system for reliably and efficiently coating a P-wave from a waveform having overlapping P-and T-waves. In addition, the pattern matching capabilities of the invention provide the added benefit of quickly and objectively comparing components of the ECG waveform, in their native or derived state. The correlation, subtraction, and derivation methods described here should also be understood to apply to data
ES 2 329 338 T3 that can be acquired from conventional 12 lead surface ECG signals as well as from intracardiac signals or combinations of both surface and intracardiac signals.
Two waveforms may be highly correlated with each other, but still poorly matched in absolute terms due to amplitude variation and drift caused by the effects of respiration. This can be a problem when the waveforms are aligned and then one is subtracted from the other. This is the reason why immediately adjacent beats are usually desirable as the reference (QRS-T) and PAC (QRS-T-P '). This is not always possible and is not practicable when performing sync projection in real time.
A methodology for monitoring the quality of T-wave subtractions is described below with reference to Figure 9. At step 902, a subtraction process is performed (as illustrated in Figures 3 and 6 and described above). to subtract a QRS-T pattern from a PAC (QRS-T-P ') and thus derive a waveform. The method of Figure 9 is performed by then providing comprehensive calculations that allow a number of measurements of interest to medical assistants, including, but not limited to: measurement of the QRS residue and the quality of the T-wave subtraction process; baseline deviation measurement, if any; and optimization of the selection of templates to be used in the subtraction process.
In step 904, the area of a derived waveform is measured. In step 906, the integral value is divided by the length of the derived waveform to normalize its value. In addition, in step 908, the amplitude of the normalized integral value is measured and represented as a voltage at the input of the ECG channel. This value of tension is called the QRS residue.
As described above, correlation analysis is used to align the QRS segment of a reference ECG pattern with the QRS segment of a PAC beat. Therefore, a further improvement can use the correlation coefficient in combination with the so-called QTS residue of the derived waveform to give an indication of the quality of the match between two beats selected for subtraction. Together, they provide an indicator of the quality of alignment or synchronization between the QRS pattern and the QRS PAC. For perfect alignment and good subtraction results, the derived QTS segment should be flat indicating a high correlation with the pattern and the QRS residue should be very small indicating a small difference in absolute amplitudes (including deviation).
Therefore, having described various embodiments of the present invention, it will be understood that the arrangement and system described above are merely illustrative of the principles of the present invention, and that other arrangements and systems may be contemplated by those skilled in the art. material without departing from the scope of the invention, as described by the claims.
Contents5
7 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7
37 members in 8 offices
Priority claims4
| Document | Office | Kind | Date |
|---|---|---|---|
| 20000247269P | United States of America | – | |
| 24726900 | United States of America | P | |
| 20010295217P | United States of America | – | |
| 29521701 | United States of America | P |
Members37
| Document | Office | Kind | |
|---|---|---|---|
| US2002065459A1 | United States of America | A1 | |
| US2002091330A1 | United States of America | A1 | |
| WO02058550A2 | World Intellectual Property Organization (WIPO) | A2 | |
| AU2002248161A1 | Australia | A1 | |
| WO02058550A3 | World Intellectual Property Organization (WIPO) | A3 | |
| WO03022148A1 | World Intellectual Property Organization (WIPO) | A1 | |
| WO02058550A8 | World Intellectual Property Organization (WIPO) | A8 | |
| EP1331876A2 | European Patent Office (EPO) | A2 | |
| EP1420690A1 | European Patent Office (EPO) | A1 | |
| US2004122332A1 | United States of America | A1 | |
| US2004127805A1 | United States of America | A1 | |
| EP1495716A2 | European Patent Office (EPO) | A2 | |
| JP2005501642A | Japan | A | |
| EP1510172A2 | European Patent Office (EPO) | A2 | |
| JP2005506097A | Japan | A | |
| EP1495716A3 | European Patent Office (EPO) | A3 | |
| EP1510172A3 | European Patent Office (EPO) | A3 | |
| US6941166B2 | United States of America | B2 | |
| US6944495B2 | United States of America | B2 | |
| US6968227B2 | United States of America | B2 | |
| US7272437B2 | United States of America | B2 | |
| EP1495716B1 | European Patent Office (EPO) | B1 | |
| AT422329T | Austria | T | |
| ATE422329T1 | Austria | T1 | |
| DE602004019362D1 | Germany | D1 | |
| ES2321190T3 | Spain | T3 | |
| EP1510172B1 | European Patent Office (EPO) | B1 | |
| EP1331876B1 | European Patent Office (EPO) | B1 | |
| DE60139162D1 | Germany | D1 | |
| DE60139497D1 | Germany | D1 | |
| ES2327734T3 | Spain | T3 | |
| ES2329338T3This record | Spain | T3 | |
| EP1420690B1 | European Patent Office (EPO) | B1 | |
| AT470393T | Austria | T | |
| ATE470393T1 | Austria | T1 | |
| DE60142362D1 | Germany | D1 | |
| ES2345139T3 | Spain | T3 |
Numbers
- Publication
- 2329338
- Application
- 1997039
Titles2
- Spanish
- SISTEMA PARA PROCESAR SEÑALES ELECTROCARDIACAS QUE TIENEN COMPLEJOS SUPERPUESTOS.
- English
- SYSTEM FOR PROCESSING ELECTRICAL SIGNALS THAT HAVE SUPERPOSED COMPLEXES.
Classification
- CPC, 5
- A61B5/35
- A61B5/7445
- A61N1/371
- A61B5/364
- A61B5/363
- IPC, 4
- A61B5 00
- A61B5 363
- A61B5 364
- A61N1 37