Abstract: In a method for automatic creation of a template for a morphology sensitive detector for an implantable cardiac stimulating device and a cardiac stimulating device operating according to the method, a predetermined length of the heart signal is recorded and filtered, all deflections exceeding a predetermined amplitude are identified and stored based on the condition that selected deflections must be separated at least by a predetermined amount of time, all selected deflections are categorized into separate classes, and the most representative class or classes for creation of the template is selected.

Abstract: Nonlinear-dynamical control, also known as chaos control, can modulate human cardiac electrophysiological dynamics by stabilizing an unstable target rhythm. Intracardiac, repolarization alternans detection methods are disclosed that operates on the basis of amplitude or repolarization duration detection. Also disclosed are control methods for stabilizing repolarization alternans.

Abstract: A method of identifying and measuring altemans in an electrocardiographic (ECG) signal representative of the electric activity of a heart of a patient. The ECG signals from the patient are divided into individual cardiac cycles and the amplitude of four segments of the repolarization portion and the depolarization portion of each cardiac cycle are measured. The amplitude for each of the repolarization segments are measured from a reference baseline that is determined by a first base segment occurring immediately prior to the repolarization portion of the present cardiac cycle and a second base segment occurring immediately before the depolarization portion of the next cardiac cycle in the sequence. Based upon the amplitude measurements over the repolarization and the depolarization portions of each cardiac cycle, digital signal processing is applied to the measurements to generate eigenvariables.

Abstract: A method for curvature based complex identification and classification comprises sensing a cardiac signal and computing curvatures at sample points on the sensed cardiac signal. Then to extract features from the computed curvatures, and compare the extracted features with a set of predetermined templates, and then to classify the sensed cardiac signal based on the outcome of the comparison.

Abstract: A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is vertical to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential value of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

Abstract: Techniques for monitoring the magnitudes of representative filtered EGM signals over time. In a typical implementation, a group of digital peak values is generated in a time period and a representative digital peak value is selected for the time period. By comparing representative peak values for several time periods, changes in signal efficacy can be identified.

Abstract: A method for curvature based complex identification and classification comprises sensing a cardiac signal and computing curvatures at sample points on the sensed cardiac signal. Then to extract features from the computed curvatures, and compare the extracted features with a set of predetermined templates, and then to classify the sensed cardiac signal based on the outcome of the comparison.

Abstract: A cardiac rhythm management system includes a sensing circuit to sense a cardiac signal and a sensing processor to detect cardiac depolarizations (beats) by utilizing certain morphological context of the sensed cardiac signal. The sensing processor samples the sensed cardiac signal, computes curvatures from the sampled cardiac signal to generate a cardiac curvature signal corresponding to the cardiac signal, derives cardiac signal features reflecting morphologically significant points along the cardiac signal from the cardiac curvature signal, and detects cardiac depolarizations based on an analysis of the cardiac signals features.

Abstract: An electrocardiogram processing technique for measuring T-wave alternans by which the alternating electrocardiogram signals are aligned to a target cubic spline. The target cubic spline is calculated on base of three isoelectric points namely a point before the P-wave, a point before the QRS-complex and a point after the T-wave. The aligned signals may then be further analyzed for variations such as T-wave alternans which are only present in alternating beats and which have diagnostic significance.

Abstract: The present invention provides a noninvasive localization, characterization and classification apparatus and method for cardiac arrhythmias. The invention enables discrete isolation of the intricate spatial and temporal detail in morphology of the atrial activity of interest from superimposed ventricular activity of a preceding heartbeat in a particular arrhythmia. An adaptive QRST subtraction template is used that is modulated for discrepancies in voltage and rate between the QRST template and arrhythmia signal. The QRST template modulation is accomplished by using one or more fiducial points and windows that are annotated in both the QRST template and the arrhythmia signal. The invention includes, but is not limited to, the isolation of atrial activity that are commonly known as: (1) P waves in case of focal atrial fibrillation, atrial tachycardia, and orthodromic AV reentrant tachycardia; (2) fibrillation waves in case of chronic atrial fibrillation; and (3) flutter waves in case of atrial flutter.

Abstract: A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is vertical to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential value of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

Abstract: In order to reduce bias associated with conventional ECG analysis, the present invention provides a method and apparatus to improve diagnosis of acute cardiac syndromes (ACS), such as acute myocardial infarction and acute cardiac ischemia (unstable angina), in specified groups of patients using ECG signals and automatic detection analysis. Specific criteria are developed and utilized based on a prespecified group selection for the particular patient. After identifying group membership for the particular patient, ECG data are acquired from a patient experiencing ACS symptoms. Known criteria typically used for assessing ACS are then modified for the particular group membership. Such criteria significantly reduce the bias found in a baseline group for which the known criteria were established.

Abstract: One embodiment enables detection of MI/I and emerging infarction in an implantable system. A plurality of devices may be used to gather and interpret data from within the heart, from the heart surface, and/or from the thoracic cavity. The apparatus may further alert the patient and/or communicate the condition to an external device or medical caregiver. Additionally, the implanted apparatus may initiate therapy of MI/I and emerging infarction.

Abstract: A method of obtaining information that corresponds to the R—R interval of electrocardiogram from the pulse-wave of a human body. The method is comprised of steps of detecting the pulse-wave of a human body in a predetermined period, differentiating the detected pulse-wave to provide a speed-pulse-wave, measuring intervals of peaks of the speed-pulse-wave, and substituting the intervals of peaks of the speed-pulse-wave for the R—R interval of the electrocardiogram.

Abstract: In a method for automatic creation of a template for a morphology sensitive detector for an implantable cardiac stimulating device and a cardiac stimulating device operating according to the method, a predetermined length of the heart signal is recorded and filtered, all deflections exceeding a predetermined amplitude are identified and stored based on the condition that selected deflections must be separated at least by a predetermined amount of time, all selected deflections are categorized into separate classes, and the most representative class or classes for creation of the template is selected.

Abstract: Disclosed is a completely implantable system that can detect the occurrence of a myocardial infarction, i.e., a heart attack, and automatically inject a thrombolytic and/or anti-thrombogenic agent into the bloodstream to promptly dissolve the thrombus that caused the myocardial infarction and prevent the formation of additional thrombi. It is well known that a myocardial infarction can be detected from a patient's electrocardiogram by noting an ST segment voltage deviation. Upon detection of a myocardial infarction, an ST segment deviation electronic detection circuit within the implanted device can produce an output signal that can cause a thrombolytic and/or anti-thrombogenic agent contained within an implanted, pressurized reservoir to immediately and automatically release medications into the patient's bloodstream. A patient warning system is also provided by an audio alarm or an electrical tickle within the human body indicating that a myocardial infarction has been detected.

Abstract: We show how to determine whether there has been an axis shift in an electrocardiogram waveform and how to use this for filtering out bad electrocardiogram information and to modify an adaptive filter that can be used to adapt the filtering of such electrocardiogram information to make it available for determining physiologic conditions even after an axis shift.

Abstract: Method of analyzing biological signals representative of voltage changes, including obtaining an analog biological signal representative of voltage changes, using digital processing software to digitize the biological signal, displaying the processed biological signal in analog form on a display in a time compressed format, wherein an amount of compression for the time compressed formal is selected such that graphical patterns are made perceivable on the display that signify an abnormality in the biological signal, and visually analyzing the biological signal on the display to characterize the abnormality.

Abstract: The present invention relates to classification and localization of arrhythmias. More specifically, a system and method is provided for developing a database of body surface ECG P wave maps for classification and localization of left-sided atrial arrhythmias. The invention includes generating and receiving P wave data in a subject by left atrial pacing or receiving P wave data in a subject during spontaneously occurring or induced left atrial arrhythmias; computing (e.g. potential or integral) maps of the P wave data; classifying the maps specific to a left atrial ectopic origin; verifying the classification procedure; averaging the classified maps into mean maps; and storing and accessing the mean maps in the database. The mean maps of the P wave data in the database can be used to automatically classify and localize P wave data from a patient obtained during a left atrial arrhythmia such as atrial tachycardia, focal atrial fibrillation or orthodromic atrioventricular reentrant tachycardia.

Abstract: A portable device (8) for recognizing Acute Myocardial Infarction by the patient himself without the help of medical doctors or technicians is described. The invention performs a real-time analysis of the ST segment (9) in an ambulatory electrocardiographic measurement environment to help the patient decide by himself that he is suffering an Acute Myocardial Infarct. The device (8) is capable of warning the user that he/she may be suffering a heart attack when the ST segment (9) is found to be depressed or elevated. The CARDIOST features a simple-to-use portable electrocardiographic amplifier (15) and a microcontroller unit (17) to analyze the ST segment (9) on the signal received from the electrocardiographic amplifier (15).

Abstract: We show how to determine whether there has been an axis shift in an electrocardiogram waveform and how to use this for filtering out bad electrocardiogram information and to modify an adaptive filter that can be used to adapt the filtering of such electrocardiogram information to make it available for determining physiologic conditions even after an axis shift.

Abstract: Angiotensin II receptor antagonists are useful for decreasing QT dispersion or inhibiting the progression of QT prolongation in patients. Also disclosed is a method for monitoring the reduction in die risk of experiencing an adverse cardiac event, such as sudden cardiac death, myocardial infarction or arrhythmias, using QT dispersion in patients treated with a therapeutically effective amount of an angiotensin II antagonist.

Abstract: Disclosed is a system for detecting a myocardial infarction (i.e., a heart attack) at the earliest possible time and promptly warning the patient that he should immediately seek medical care. Specifically, a first embodiment of the present invention has an implantable electronic system that can sense a change in the patient's electrogram that is indicative of a myocardial infarction. If a myocardial infarction is sensed, the device would then cause an implantable or externally located alarm means such as an audio sound to be actuated to warn the patient of his condition. The patient could then promptly seek medical care, for example, at a hospital emergency room. Having been trained to recognize such an alarm, most patient would neither fail to recognize such an indication of a myocardial infarction nor would they ignore such an alarm signal if it were to occur.

Abstract: A system and a method for classifying cardiac complexes based on cardiac information derived from two or more cardiac signals. Two or more cardiac signals containing cardiac complexes are monitored. A cardiac complex in the two or more cardiac signals is isolated in an analysis window. The morphology of the cardiac complex in each of the two or more cardiac signals is then compared to the morphology of a template cardiac complex representing a predetermined cardiac condition. Based on this comparison, the cardiac complex is classified as either belonging or not belonging to the predetermined cardiac condition.

Abstract: A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is normal to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential values of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

Abstract: A pacing system and method for determining a heart failure condition such as left ventricular dysfunction in a patient are provided, based upon obtaining information from cardiac signals, which information is processed and examined for an indication of the onset or progression of LVD. Since LVD is generally characterized by conduction disorders and other body responses calling for different heart rates during exercise, an examination of sensed cardiac signals is utilized to obtain data reflective of an LVD condition. In one embodiment, a QT rate responsive pacemaker is utilized, wherein variations in QT interval corresponding to heart rate are detected and stored, and then periodically analyzed to detect changes of sufficient magnitude to indicate onset of LVD. In another embodiment, changes in lower natural rate at nighttime or rest are monitored and analyzed for detection for a trend indicating LVD.

Abstract: In determining whether a patient has ischemia or other conditions discernible in the variation occurring in the ST portion of the electrocardiogram signal, we filter out bad ST change parameters that are not changing at a rate representative of human ischemia ST change parameter rates of change. This can be used for driving therapy systems to alleviate cardiac ischemia. This filtering can be enhanced by using multiple cardiac electrical vectors for the electrogram signal vectors, and using a determination of Axis shift to modify filter parameters and the expected ranges of precursors to the ST change parameter (an ST change variable) to eliminate bad cardiac cycles, that is cardiac cycle information that may be misleading.

Abstract: In using electrogram signals to determine physiologic conditions like ischemia, the bad cardiac cycle information due to noise, axis shifts in the cardiac electrical axis, and the like must be removed if the electrogram signal can be made to be a good indicator. If this is accomplished through the adaptive filtering techniques shown here, the signal can be used to drive a closed loop therapy system responsive to those physiologic conditions discernible from good cardiac cycle electrocardiogram signals.

Abstract: Disclosed is a completely implantable system that can detect the occurrence of a myocardial infarction, i.e., a heart attack, and automatically inject a thrombolytic and/or anti-thrombogenic agent into the bloodstream to promptly dissolve the thrombus that caused the myocardial infarction and prevent the formation of additional thrombi. It is well known that a myocardial infarction can be detected from a patient's electrocardiogram by noting an ST segment voltage deviation as compared to the voltage of the patient's TP or PQ segments. Upon detection of a myocardial infarction, an ST segment deviation electronic detection circuit within the implanted device can produce an output signal that can cause a thrombolytic and/or anti-thrombogenic agent contained within an implanted, pressurized reservoir to immediately and automatically release medications into the patient's bloodstream.

Abstract: Method and apparatus for detecting changes in electrocardiogram signals. A first cardiac electrogram signal is sensed, where the first cardiac electrogram signal has a voltage and includes a first cardiac complex. A ventricular activation is detected in the first cardiac complex and a first timer is started, where the first timer times a first specified time. A first voltage value is measured from the first cardiac electrogram signal at the first specified time after the ventricular activation. A second voltage value is also measured from a defined portion of the first cardiac electrogram signal. A comparison value is then calculated from the first and second voltage values measured from the first cardiac electrogram signal. The first voltage value is recorded when the comparison value is greater than or equal to a predetermined value.

Abstract: An automatic sensing system for an implantable cardiac rhythm management device comprises a variable gain amplifier and associated filters where the gain of the amplifier is adjusted as a function of the peak amplitude of a cardiac depolarization signal (either a P-wave or an R-wave) and especially the relationship of the peak value to a maximum value dictated by the circuit's power supply rail. The trip point comparator has its trip point adjusted as a function of the difference between the detected peak value of the signal of interest and the peak value of noise not eliminated by the filtering employed.

Abstract: Noise is reduced from a received ECG signal representative of activity of the heart of a patient. A collection of beats from the ECG signal is selected and transformed into a multi-dimensional representation. A multi-dimensional filter function is applied to the multi-dimensional representation to enhance a signal-to-noise ratio of the collection of beats.

Abstract: A method and system for determining Acute Myocardial Infarction. The method and system work by determining whether or not at least one pre-specified component wave is present within each successive heartbeat waveform (e.g. the S wave component of the QRSTU waveform) appearing within each electrocardiographic lead. After it has been determined whether or not the pre-specified component wave is present within the heartbeat waveforms under consideration (each lead will generally have some representation of each successive heartbeat waveform present within it), a wave amplitude ratio (e.g. the ST complex amplitude divided by the S wave component amplitude at some specified instant in time) is calculated. Thus, for each successive heartbeat waveform there will generally be at least one wave amplitude ratio calculated for each electrocardiographic lead, since the same heartbeat waveform generally appears, in some form, within each electrocardiographic lead.

Abstract: A ventricular tachycardia (VT) complex is distinguished from a sinus tachycardia or a supraventricular tachycardia. A template based on morphology of a normal sinus rhythm is collected. A test signal is compared against the template to determine how closely the test and template signals correspond based on morphology. The comparison is done based on peak information in the template and the test signal. A score is generated to indicate the degree of similarity between the template and the test signal. The peak information is extracted as follows. First, a group of three consecutive peaks having a largest cumulative peak amplitude is located in the template and in the test signal. The polarity, position and area of each peak within the group is then determined. The area of each peak is normalized. The polarities, positions and normalized areas represent the peak information that is used for comparison.

Abstract: The present invention is a method and apparatus for processing a sensed atrial electrogram in conjunction with a sensed ventricular electrogram. The present invention permits accurate discrimination of atrial P-waves from far field ventricular events such as far field R-waves and avoids oversensing such far field ventricular events as atrial sense events and undersensing atrial events occurring within a fusion beat masked by a far field ventricular event in the atrial electrogram. Atrial channel trigger signals are generated in response to sensed P-waves and far field R-waves in the atrial electrogram, and ventricular trigger signals are generated in response to sensed R-waves in the ventricular electrogram.