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: A quantitative method and apparatus for measuring a cardiac function interval. Beat-to-beat data representative of a cardiac interval is collected over an extended period of time. A series of bins, each of which has a defined value range, is defined. The collected data is organized into the bins in accordance with the value of the data and the value range of the bin. The percentage of data in each bin may be calculated based upon the quantity of data in each bin.

Abstract: A medical device and method for predicting cardiac arrhythmias, by gathering electrocardiographic data such as intervals between heart beats (RR-series) or other signal, mathematically decomposing or compressing the signal into several elements or components that contain the most significant information and tracking the changes in the several elements. The signal may be divided into time windows, and the signals decomposed into a plurality of coefficients or components such as Karhunen Loeve Transformation (KLT) coefficients that are predictive of the occurrence of a cardiac arrhythmia. The electrocardiographic data may be generated real-time, on-line, or be prerecorded data.

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: The invention relates to a method of measuring a vital function and a measuring device implementing the method. The measuring device receives for example heart pulses as signal episodes. The measuring device calculates a coherent average of the signal episodes in an averaging unit to determine the wave form of the signal episode. The measuring device also preferably comprises an adapted filter the impulse response of which is based on the coherent average of the signal episode.

Abstract: A cardiac rhythm management system recognizes patterns of interval durations, distinguishing between events in different heart chambers even though signals associated with those different heart chambers are processed using a commonly shared sensing circuit. A therapy delivery algorithm ignores intervals between cardiac events occurring in different heart chambers when determining a cardiac rate upon which the delivery of therapy is based. This reduces the risk of inappropriate delivery of therapy to the patient. Delayed conduction left ventricular beats are not erroneously recognized as a subsequent right ventricular beat, preventing such short intervals from inappropriately triggering a defibrillation countershock. The system detects cardiac events, obtains a current interval between a current cardiac event and a previous cardiac event, and classifies the current interval into at least first and second categories, based on a duration of the current interval.

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 compression algorithm for the compression of ECG recordings uses the Karhunen-Loeve Transform (KLT) to transform a set of N sampled ECG beats from a matrix of N.times.M samples into a new form, from which a selected subset can be retained for storage, transmission, or analysis. In order to reduce computation time and storage space, a multirate downsampling operation may be applied, which retains the appropriate spectral information in each block. The downsampled beats are then padded to make them of uniform size, and a Karhunen-Loeve Transform is applied to the sample set. Coefficients from the Karhunen-Loeve Transform of the sample set are retained for reconstruction according to one of two criteria. The average variance of the reconstructed sample set may be controlled, or different numbers of coefficients may be retained for each beat. The KLT compressed data may be reconstituted by reverse KLT transforming the data.

Abstract: An implantable apparatus for the detection and monitoring of spontaneous cardiac electrogram features in a comprises a cardiac monitoring device and a plurality of subcutaneous cardiac sensing electrodes electrically connected to the monitoring device. The sensing electrodes are configured for sensing cardiac electrogram features when implanted in spatially separate locations in a patient. A storage device contained within the monitoring device is operably associated with the subcutaneous electrodes and stores the cardiac electrogram features. Preferably, the plurality of subcutaneous electrodes are carried by a single elongate lead. A downloading device such as telemetry apparatus or transcutaneous electrical connectors may be provided so that the stored information can be downloaded to a separate apparatus external to the patient. In a preferred embodiment, the apparataus is a defibrillator. Methods of using such apparatus are also disclosed.

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: A medical device and method for predicting life-threatening cardiac arrhythmias (LTCA) by gathering electrocardiographic data such as intervals between heart beats (RR-series) or other signal, mathematically decomposing or compressing the signal into several elements or components that contain the most significant information and tracking the changes in the several elements. The signal may be divided into time windows, and the signals decomposed into a plurality of coefficients or components such as Karhunen Loeve Transformation (KLT) coefficients that are predictive of the occurrence of LTCA. The electrocardiographic data may be generated real-time, on-line, or be prerecorded data.

Abstract: The invention disclosed herein relates to an implantable medical device for detection and treatment of syncope comprising an algorithm for determining the presence of syncope based on physiological activity associated with the onset of a syncopal episode, and a means for infusion a drug. Drug infusion therapy may be used along or in combination with pacing. The physiological activities detected and used by the device are selected from the group including changes in heart rate, heart rate variability, QT interval, PR interval, pressure, blood flow, vagal nerve activity, temperature, pH, and AV conduction times, respiration rate, position, motion, and combinations thereof. Drugs which may be used with the invention include pharmaceutical compositions which are capable of both endocardial administration and treatment of syncope, such as compositions comprising beta-blockers.

Abstract: Abnormal cardiac activity in a patient may be detected by acquiring an electrocardiogram waveform associated with a first level of physiologic activity of the patient and an electrocardiogram waveform associated with a second, different level of physiologic activity of the patient. QRS complexes of the electrocardiogram waveforms are compared to identify an abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity. The abnormal portion of the QRS complex is processed to detect abnormal physiologic activity.

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 apparatus for analyzing QT dispersions in ECG lead signals, comprising acquiring a plurality of ECG lead signals, filtering said signals to remove noise without distorting the T-wave morphology, determining critical T-wave marker points, and calculating QT dispersion and their heart rate corrected values from the determined markers. The apparatus comprises a processor programmed to perform these functions.

Abstract: A method and apparatus for processing biological signals on an event basis. An event low pass filter (LPF) is provided which passes variations in event features below an event cut-off value, which is analogous to the time-based cutoff frequency. An event high pass filter (HPF) is provided which passes variations in event features that are above an event-rate cutoff. An event variability detector is provided which determines the variation of a discrete variable from values at prior events. An event discriminator is provided for filtering out contributions of unrelated events that are superimposed on a discrete periodic measurement of interest. In all of these techniques, sampling of a biological signal is performed in coincidence with a biological event which does not occur at a constant frequency. In accordance with another aspect, an algorithm is provided using event-based techniques for discriminating abnormal rhythms from normal sinus rhythm on the basis of atrial rate, ventricular rate, and A-V intervals.

Abstract: The method for assessing risk of an adverse clinical event includes detecting a physiologic signal in the subject and determining from the physiologic signal a sequence of intervals corresponding to time intervals between heart beats. The long-time structure of fluctuations in the intervals over a time period of more than fifteen minutes is analyzed to assess risk of an adverse clinical event. In a preferred embodiment, the physiologic signal is an electrocardiogram and the time period is at least fifteen minutes. A preferred method for analyzing the long-time structure variability in the intervals includes computing the power spectrum and fitting the power spectrum to a power law dependence on frequency over a selected frequency range such as 10.sup.-4 to 10.sup.-2 Hz. Characteristics of the long-time structure fluctuations in the intervals is used to assess risk of an adverse clinical event.