33 results about "T wave alternans" patented technology

Various techniques are provided for assessing the reliability of left atrial pressure (LAP) estimates made by an implantable medical device based on impedance values or related electrical values. In one example, various cardioelectric and cardiomechanical parameters are used to corroborate LAP estimation in circumstances where the LAP estimates deviate from an acceptable, satisfactory or otherwise healthy range. The cardioelectric parameters include, e.g.: ST elevation; heart rate (HR); heart rate variability (HRV); T-wave alternans (TWA); QRS waveform parameters; P-wave duration; evoked response (ER) parameters; and intrinsic PV/AV/VV conduction delays. The cardiomechanical parameters include, e.g.: heart rate turbulence (HRT); cardiogenic impedance signals; heart sounds; and non-LAP blood pressure measurements, such as aortic pressure measurements. The device compares the cardioelectric and cardiomechanical parameters against corresponding baseline values to determine whether variations in the parameters corroborate the LAP estimates. If not, the LAP estimates are selectively cancelled or suspended, or the overall procedure is re-calibrated.

A system to detect the presence or absence of T wave alternans is described based on statistical tests and periodicity transform. T wave and ST segment boundaries are detected in multi-lead ECG signals acquired from the regular clinical leads. Once the fiducial point and the above boundaries are delineated, computation of regular parameters like T wave amplitude, area under the T waves or segments of T wave, ST segment slope and/or the curvature of T wave are performed. Each parameter forms a rolling array of values with each successive beat. The array of values, or the time series, is used to make the decision about the T wave alternans. Two different methods are employed based on periodicity transforms and statistical tests. A set of numerical values (e.g. norm of the projection on to p-2 space, sums of adjacent terms after the trend removal, t-value, and number of deviations from alternans pattern) are all computed and compared to threshold values. Threshold values are computed from past information and experience with clinical databases and simulations. Final system comprises a software module, which can be part of the existing ECG monitoring programs as well as external defibrillator modules, apart from being stand-alone algorithms.

The invention discloses a dynamic electrocardiogram (ECG) T wave alternate quantitative analysis method based on models, which belongs to the technical field of biomedical signal processing. The dynamic electrocardiogram (ECG) T wave alternate quantitative analysis method includes steps of preprocessing 12 lead ambulatory electrocardiograms of a patient at first and removing random disturbance including baseline drift, power frequency disturbance, myoelectricity noise and the like; building various channel electrocardiosignal state space models and realizing robust estimation to electrocardiosignal waveforms by the aid of a dynamic multi-scale state estimation theory; applying a multi-sensor data fusion method to realize T wave fusion extraction and realizing T wave quantitative description; and finally realizing quantitative analysis for T wave alternate signals according to the analytic function of T waves. The dynamic electrocardiogram T wave alternate quantitative analysis method has the advantages that on the basis of the electrocardiosignal state spatial models, T wave quantitative analysis is realized at first, then dynamic electrocardiogram T wave alternate real-time detection and analysis are realized, and accordingly the dynamic electrocardiogram T wave alternate quantitative analysis method is convenient for catching T wave alternate electrocardio abnormal conditions suddenly caused in daily life and increases detecting level and diagnosis ability to patients in danger of sudden cardiac death.

The invention discloses an electrocardiosignal analysis method of a T wave alternans scatter diagram method based on morphology. Aiming at the defects of difficulty in detection of each heart beat T wave alternans amplitude value and complexity in calculation of T wave alternans detection by the spectrum analysis method, the T wave alternans scatter diagram method based on morphology is provided to provide a new effective quantitative index of T wave alternans detection for development of domestic related clinical researches. The method includes: using the T wave window analysis method for sampling T waves of 128 continuous heart beats selected from the American MIT-BIH standard heart beat irregularity database and the European ST-T electrocardio database, making a differential scatter diagram by the aid of the sample points, using vector angle index of the scatter diagram for quantitative analysis of T wave alternans to obtain a vector angle index range for judging whether T wave alternans exists or not, and comparing a T wave alternans detection result obtained by means of the vector angle index of the scatter diagram with the T wave alternans detection result obtained by means of the T wave alternans amplitude of the spectrum analysis method to judge reliability in detection of T wave alternans by the vector angle index.

Embodiments of the present invention relate to implantable systems, and methods for use therein, that can detect T-wave alternans and analyze the detected alternans to provide information regarding cardiac instabilities and predict impending arrhythmias.

The invention discloses a method for detecting TWA (T wave alternans) in the electrocardiogram and belongs to the technical field of medical testing. The method comprises the following steps of: eliminating data sections with excessively high noise from selected electrocardiosignals by judging in the earlier stage so as to obtain relatively stable data suitable to analyze and carrying out analysis by taking M beats as an analysis window; firstly, extracting a T wave matrix for the M beats of electrocardiosignals and then carrying out data fitting on T waves in the T wave matrix to obtain a novel T wave matrix; respectively calculating alternans correlation indexes by a correlation analysis method to obtain an ACI (Allowable Concentration Index) of the integral analysis window); then judging whether the TWA exists in the integral analysis window by the correlation analysis method; if the TWA exists in the integral analysis window, respectively carrying out least square linear fitting on sectional odd and even beats of the existing TWA and calculating an actual TWA quantity; and if the TWA does not exist in the integral analysis window, intercepting a next analysis window to carry out analysis. According to the invention, the TWA signals can be effectively detected from the time domain angle and the TWA quantity is accurately quantized.

The invention relates to a non-invasive attached telemetering electrocardiographic recording method having an ultra-long record period and an ultra-high storage capacity. By using the method, characteristic values of electrocardiographic waves can be safely, stably and clearly acquired under the natural physiological state of a human body within a long period (more than 15 days), microvolt-level measurements of T-wave alternans can be acquired, and the collection, processing and high-capacity storage of electrocardiographic waves can be completed; and multiple electrocardiographic recording pasters can be used to realize the simultaneous recording of multi-channel body surface electrocardiograms, and a computer data processing and analysis system can complete the data monitoring and analysis, image display, data storage and printing and output of the recorded signals and realize the networking transmission of the electrocardiosignals. The clinical indications of the device include: symptoms related to suspected arrhythmia; determination of arrhythmia property, and completion of reasonably evaluating anti-arrhythmia treatment and monitoring myocardial ischemia; evaluation of anemic heart disease treatment measures; instructions to acute myocardial infarction patients before leaving hospital and during convalescence; and installation, detection and function assessment of sudden cardiac death and heart pacemakers.

The invention disclosed includes a method and apparatus for calculation of T-wave alternas in electrocardiographic (ECG) signals; said method comprises the following method steps: (a) collecting and storing an ECG signal; (b) detecting each heartbeat T-wave in the ECG signal using an automatic detection and segmentation algorithm; (c) classifying said heartbeat T-wave as an even or odd heartbeat T-wave; (d) initializing said method by taking the first even and the first odd heartbeat T-wave as their respective initial average; (e) processing all the heartbeat T-waves in the ECG signal to generate an even heartbeat T-wave weighted average and odd heartbeat T-wave weighted average; and (f) calculating TWA using a distance metric between the even heartbeat weighted average and the odd heartbeat weighted average, said distance metric including curve matching Continuous Dynamic Time Warping (CDTW).

A system and method for use in an implantable cardiac device that delivers electrical therapy to a patient's heart determines if a T wave alternan pattern of the patient's heart exists. The system includes a sensing circuit that generates an electrical signal representing electrical activity of the patient's heart. A morphology detector measures a magnitude of a T wave characteristic of each T wave in the electrical signal of a predetermined number of cardiac cycles of the heart. A discriminator then determines, responsive to the measured T wave characteristic magnitudes, if a T wave alternan pattern exists. A T wave alternan pattern may be determined to exist if the number of measured T wave characteristic magnitudes greater than and less than a T wave characteristic magnitude baseline are substantially equal and each greater than a given number.

Embodiments of the present invention relate to implantable systems, and method for use therein, that can detect T-wave alternans. In accordance with specific embodiments of the present invention, intrinsic premature contractions of the ventricles are detected, and at least one metric of T-waves is measured in a specified number of beats that follow each detected intrinsic premature contraction of the ventricles. A determination of whether T-wave alternans are present is made based on the measured T-wave metrics. In alternative embodiments, rather than waiting for intrinsic premature contractions of the ventricles, premature contractions of the ventricles are caused on demand by inducing premature atrial contractions. In still other embodiments, a patient's vagus nerve is stimulated to simulate premature contractions of the ventricles. This abstract is not intended to be a complete description of, or limit the scope of, the invention.

The method and system comprise receiving digitized ECG data including a plurality of alternating consecutive odd and even beats (302), calculating a variability for at least one odd or even beat (304), and excluding certain beats from T-wave alternant measurements according to an exclusion procedure (310).

The invention discloses a T wave dynamic modeling and multi channel estimation fusion method. Aiming to solve the problems of T wave asymmetry, beat-to-beat dynamic change, myoelectricity pulses in highly dynamic monitoring environment and electrode pulse noise interference, a T wave state space model adaptive to the beat-to-beat dynamic estimation is provided, on the basis of extended Kalman filter, a multi-channel T wave estimation fusion frame is established, T wave parameters with eight independent channels are combined, and T wave robustness estimation in strong noise background can be implemented. The method has the advantages that the sectional characteristics of electrocardiosignals are utilized completely, an analysis module adaptive to asymmetrical T wave estimation is established, the T wave analysis presentation is utilized, the T wave data with eight independent channels are fused completely, the robustness of the T wave beat-to-beat dynamic estimation is improved, and necessary theoretical and technical basis is provided for beat-to-beat detection and estimation of T wave alternating signals in the highly dynamic monitoring environment.

The invention discloses a multifunctional puncture system for the department of pediatrics. The multifunctional puncture system is characterized in that an image processing module is built in a CT imaging module and comprises an image capture unit, a data acquisition unit, a data conversion unit, an identification pattern generation unit, an image processing unit and a detection optimization module; a puncture module is provided with an intelligent electrocardiogram analysis module and an emotion sensing module; the intelligent electrocardiogram analysis module comprises an intelligent analysis unit as well as an electrocardiogram signal noise analysis unit and a T-wave alternans scatter diagram electrocardiogram signal analysis unit which are connected with the intelligent analysis unit. CT detection is performed on a puncture part, internal images are displayed on the CT imaging module during detection, a puncture operation can be performed on a patient visually with a puncture needle, physical signs are monitored in the whole operation process by means of the CT imaging module, the intelligent electrocardiogram analysis module and the emotion sensing module, and smooth finishing of the puncture operation is facilitated.

A T-wave alternans (TWA) measuring apparatus is configured to group electrocardiogram (ECG) waveforms in increments of a first beat, to test a statistical intergroup difference for the correponding first groups, and to determine that a heartbeat condition is unstable, when a significant statistical difference exists between the first groups. The apparatus is further configured to determine the magnitude of TWA when it is determined that the heartbeat condition is unstable. The ECG waveforms may further be grouped in increments of a second beat number to generate second groups, and to determine that the heartbeat condition is unstable when a significant statistical difference exists between the first groups but not between the second groups.