Abstract: A system, method, or device classifies an arrhythmia according to the temporal order in which a depolarization wave associated with a particular heart contraction is received at a plurality of electrodes. One or more antiarrhythmia therapies is mapped to each arrhythmia classification. When a particularly classified arrhythmia is detected, the correspondingly mapped therapy list is selected and an appropriate antiarrhythmia therapy delivered. In one example, the particular therapy delivered in response to an arrhythmia depends at least in part on its historical success in treating arrhythmias of that classification.

Abstract: A system and method for classifying cardiac complexes sensed during a tachycardia episode. A first cardiac signal and a second cardiac signal are sensed, where the first cardiac signal has a voltage. A first cardiac complex and a second cardiac complex of a cardiac cycle are detected in the first and second cardiac signal, respectively. A predetermined alignment feature is identified in the second cardiac complex. A datum is defined, or positioned, at a specified interval from the predetermined alignment feature of the second cardiac complex. Voltage values are then measured from the first cardiac complex at each of two or more measurement intervals from the datum. The voltage values are then compared voltage values measured from NSR cardiac complexes to classify the first cardiac complex is either a ventricular tachycardia complex or a supraventricular tachycardiac complex.

Abstract: An active implantable medical device, in particular a defibrillator/cardioverter, with a sophisticated discrimination of atrial fibrillations. This device is able to deliver therapy for defibrillation, cardioversion, and/or ventricular and/or atrial antitachycardiac pacing stimulation; sense the ventricular and atrial activity; identify a suspicion of and confirm the presence of episodes of tachycardia in the activity thus sensed; analyze the stability of detected RR intervals and the stability of the associated PR intervals; and, in the event of a detection of stable RR intervals and unstable PR intervals, discriminate between atrial fibrillation with fast ventricular rhythm and atrial fibrillation with ventricular tachycardia, and to control delivery of a differentiated therapy according to one case or the other. A bi-tachycardia discrimination also can be made.

Abstract: Implantable medical devices and methods of tachycardia detection that provide adjustable detection criteria based upon a hemodynamic parameter. In some embodiments, the apparatus and methods provide for detection and delivery of therapy for hemodynamically stable and hemodynamically unstable tachycardias by varying a number of intervals detected (NID) threshold based on hemodynamic measurements.

Abstract: An apparatus and method for detecting an atrial fibrillation through monitoring the R—R intervals of a patient's QRS complexes. Ratios of the current R—R interval are made to previous R—R intervals. Multiple moving averages are taken of the ratio results. The ratios are compared to a validating threshold and if the particular ratio is within a selected range, a moving average is calculated with inclusion of the present R—R interval. If the ratio is outside the range, a moving average is calculated without inclusion of the current R—R interval. The moving averages are combined and this difference average is compared to a trigger threshold. If the difference average exceeds the threshold, an atrial fibrillation is determined to exist, a memory trigger is provided, and the QRS complex data within a selected period of time about the atrial fibrillation event are recorded and removed from overwrite status in the memory.

Abstract: An apparatus for determining when a patient is susceptible to defibrillation comprises a plurality of electrodes (12, 14) for obtaining an ECG signal from a patient, and data processing means (30, 42) for determining a region of the ECG signal where the signal passes from a first threshold to a second threshold at least equal in magnitude but of opposite polarity to the first threshold while the gradient of the signal remains within certain limits, detecting the next following ECG signal peak, and providing an output signal upon such detection.

Abstract: An implantable cardiac stimulation device and method provides reliable sensing of cardiac events to support cardiac pacing or fibrillation detection. The device comprises a sensing circuit that senses the cardiac events in accordance with a plurality of threshold characterizing parameters. A parameter control adjusts the threshold parameters responsive to the rate of the sensed cardiac events in a manner which precludes positive feedback to prevent continued oversensing, undersensing, or noise sensing.

Abstract: A medical device system that receives cardiac data representing a plurality of stored arrhythmic episodes, and analyzing the cardiac data to identify and display a subset of stored arrhythmic episodes as a function of user-specified episode criteria. The medical device system presents a query window on an interactive display in order to receive user-specified episode criteria via one or more input fields. The medical device displays only those episodes matching the episode criteria such as arrhythmia type, zone of detection, date of occurrence and average heart rate in beats per minute (BPM).

Abstract: A system and method for prioritizing multiple health disorders for use in automated patient care is described. A plurality of monitoring sets are retrieved from a database. Each of the monitoring sets include stored measures relating to patient information recorded and derived on a substantially continuous basis. A patient status change is determined by comparing at least one stored measure from each of the monitoring sets to at least one other stored measure with both stored measures relating to the same type of patient information. Each patient status change is ordered in temporal sequence from least recent to most recent. A plurality of health disorder candidates categorized by quantifiable physiological measures of pathophysiologies indicative of each respective health disorder are evaluated and the health disorder candidate with the pathophysiology most closely matching those patient status changes which occurred least recently is identified.

Abstract: An automated system and method for diagnosing and monitoring the outcomes of atrial fibrillation is described. A plurality of monitoring sets is retrieved from a database. Each of the monitoring sets include recorded measures relating to patient information recorded on a substantially continuous basis. A patient status change is determined in response to an atrial fibrillation diagnosis by comparing at least one recorded measure from each of the monitoring sets to at least one other recorded measure. Both recorded measures relate to the same type of patient information. Each patient status change is tested against an indicator threshold corresponding to the same type of patient information as the recorded measures which were compared. The indicator threshold corresponds to a quantifiable physiological measure of a pathophysiology resulting from atrial fibrillation.

Abstract: A method of determining a state of ventricular fibrillation, includes: measuring the rhythm of the heart during ventricular fibrillation for a period of time; creating a phase space reconstruction of the measured ventricular fibrillation heart rhythm; determining a first value related to the rate of change of the leading edge of the phase space reconstruction over the period of time; and determining the state of ventricular fibrillation by relating the first value to the state of ventricular fibrillation. A defibrillation system for use in treatment of ventricular fibrillation includes at least one sensor to measure heart rhythm and at least one applicator to apply a defibrillation pulse to a patient (either a human or another member of the animal kingdom). The system further includes at least one processor in communication with the sensor and the applicator.

Abstract: The method and the device serve for detecting an anomaly in the cardiac activity of a patient and for carrying out a defibrillation. At least one sensor acquires at least one parameter that characterizes the cardiac activity of a patient. An automatic evaluation with respect to at least one parameter that characterizes the anomaly in the cardiac activity is carried out, and an alarm signal is generated if a limiting value for at least one parameter that characterizes the anomaly is exceeded. The defibrillator is realized in the form of a mobile unit and contains a voltage generator, a control unit and at least two electrodes.

Abstract: A cardiac rhythm management system that includes a pacemaker configured for resynchronization pacing and an external programmer with an associated display for displaying electrogram markers. The markers are designed to relate information to a user in a manner suited for biventricular or other resynchronization pacing.

Abstract: The present invention relates generally to analysis of electrocardiograms (ECGs) during atrial fibrillation. In particular, the invention relates to the use of such methods for the the creation and validation of cardiac models and use in the refined diagnosis of heart disease.

Abstract: Techniques for detecting atrial fibrillation via a ventricular lead are described. An implantable medical device according to the invention may monitor a ventricular depolarization rate via the ventricular lead in order to detect the effect of conducted atrial fibrillation of the ventricular rate. For example, the implantable medical device may detect an increase in the ventricular rate, or a decrease in the stability of the ventricular rate. The implantable medical device may also detect the effect of delivery of a pacing pulse on the length of an R-R interval subsequent to the delivery. A compensatory pause following delivery of a pacing pulse may indicate the presence of conducted atrial fibrillation. The implantable medical device may store information relating to detected episodes of atrial fibrillation for later review by a physician, so that atrial fibrillation may be diagnosed in situations where it might not otherwise be detected.

Abstract: Determining termination of an identified tachyarrhythmia episode may involve analysis of a relative decrease in tachyarrhythmia rate, a normalization of electrogram morphology criteria, or both. An implanted medical device may obtain a tachyarrhythmia rate and a morphology of a cardiac waveform. The device may compare the tachyarrhythmia rate to a threshold tachyarrhythmia rate and the morphology to a template morphology, and classify the heart beat as indicating termination of the tachyarrhythmia episode when the tachyarrhythmia rate is less than the threshold tachyarrhythmia rate, the morphology categorizes as normal, or both. For arrhythmias with no therapy delivered, observation of arrhythmia behavior at the point of termination may lead to improved classification. In addition, observation of a relative decrease in tachyarrhythmia rate immediately after therapy application can lead to application of slower but more specific criteria for redetection.

Abstract: A system for diagnosing and monitoring outcomes of atrial fibrillation for remote patient care is presented. A database stores monitoring sets containing recorded measures relating to patient information recorded on a substantially continuous basis. A server retrieving and processing a plurality of the monitoring sets includes a comparison module receiving a diagnosis of atrial fibrillation and determining patient status changes in response to the atrial fibrillation diagnosis by comparing periodically recorded measures from each of the monitoring sets to other recorded measures from another of the monitoring sets with both recorded measures relating to a same type of patient information; and an analysis module evaluating on a periodic basis each patient status change for an absence, an onset, a progression, a regression, and a status quo of atrial fibrillation against a predetermined indicator threshold corresponding to the same type of patient information as the recorded measures which were compared.

Abstract: Ablation of the pulmonary veins causes damage to the tissue which may affect the viability of the tissue. By placing a stent, a vascular endoprosthesis, within a target pulmonary vein it is possible to protect the functionality of the veins after the ablation procedure. Placement of a stent, endoprosthesis or mere circuit interrupting structure into a target pulmonary vein, without ablation, prevents aberrant electrical activity in the pulmonary veins from interfering with the electrical activity of the left atrium. The stent, endoprosthesis or circuit interrupting structure may also be coated or comprised of a drug-eluting compound, loaded with a drug which inhibits arrhythmia.

Abstract: Implantable medical devices (IMDs) are adapted for developing a vectorcardiograph (VCG) from signals across pairs of electrodes. Sense amplifiers of the IMD are calibrated to correlate the signals to reference sagittal, horizontal and frontal planes of the body. Polar coordinate data is plotted over the time of occurrence of the sensed PQRST electrogram as at least one of an x-axis vector projected into the reference sagittal plane as a sagittal VCG, a y-axis vector projected into the reference horizontal plane as a horizontal VCG, a z-axis vector projected into the reference frontal plane as a frontal VCG, and an xyz-vector in 3-D space. The VCG loops plotted by each of the vectors can also be derived. Thresholding and template matching techniques determine one or more of the maximum vector magnitude and orientation, average axis vector magnitude and orientation, the loop shape, and the loop area representing a particular heart rhythm.

Abstract: Devices, systems, and methods for localizing and/or treating arrhythmias of a patient's heart, which are particularly useful for localizing focal atrial fibrillation, allow locating arrhythmogenic regions of a chamber of the heart using heart cycle signals measured from a body surface of the patient. Non-invasive localization of the ectopic origin or exit site allows focal, circular, and/or perimeter treatment to be directed so as to inhibit complex arrhythmias without having to rely on wide-spread and time consuming sequential searches and/or on massively invasive simultaneous electrocardial sensors. The invention recognizes that effective localization of these complex arrhythmias can be significantly enhanced by techniques and structures which separate heart cycle signals originating from differing chambers and/or regions of the heart tissue.

Abstract: A method and system for discrimination of supraventricular tachycardia and ventricular tachycardia events. Morphological features points are extracted from normal sinus rhythm (NSR) complexes and used to generate a NSR template. A numerical convolution is performed using the NSR template and the feature points for each sensed NSR to give a NSR filter output. Using a plurality of NSR complexes, a median NSR filter output template is determined, where the median NSR filter output template has a median value for each value in the NSR filter output. The median NSR filter output template is then used during a tachycardia event to distinguish tachycardia events as either ventricular tachycardia events or supraventricular tachycardia events.

Abstract: An algorithm for detection of tachycardias and for discriminating between supraventricular tachycardia (SVT) and ventricular tachycardia (VT) when a 1:1 tachycardia condition is present that can be implemented in an implantable cardiac rhythm management device. Variability measures of AV and VA intervals during the tachycardia are computed and used to distinguish between SVT and VT.

Abstract: A method of generating a template in an implantable medical device for implantation within a patient, and a processor readable medium for performing the method, that includes generating a template corresponding to a supraventricular rhythm of the patient, determining whether the template is valid, and monitoring the template to determine whether the template is an accurate representation of the supraventricular rhythm. The template is created from non-paced R waves that are below a predetermined heart rate, and a statistical validation of the template is performed by evaluating the template based on matches against ongoing slow heart rhythm. The quality of the template is continuously monitored, similar to the statistical validation, with the exception that one thousand beats are evaluated and once more than thirty out of the last one hundred beats do not match the template within the threshold, an attempt is made to create a new template.

Abstract: Detection of arrhythmias is facilitated using irregularity of ventricular beats measured by delta-RR (&Dgr;RR) intervals that exhibit discriminatory signatures when plotted in a Lorenz scatter-plot. An “AF signature metric” is established characteristic of episodes of AF that exhibit highly scattered (sparse) distributions or formations of 2-D data points. An “AFL signature metric” is established characteristic of episodes of AFL that exhibit a highly concentrated (clustered) distribution or formation of 2-D data points. A set of heart beat interval data is quantified to generate highly scattered (sparse) formations as a first discrimination metric and highly concentrated (clustered) distributions or formations as a second discrimination metric. The first discrimination metric is compared to the AF signature metric, and/or the second discrimination metric is compared to the AFL signature metric.

Abstract: A cardiac lead has an end adapted for contact with cardiac tissue that has a number of dot-like electrodes which are separated from each other by electrically insulating material, and which are positioned at respective locations adapted for simultaneous contact with the cardiac tissue. The dot-like electrodes produce respective unipolar signals. At least one difference signal from the unipolar signals of a pair of the dot-like electrodes. The difference signal is edited in circuitry of a cardiac assist device and is compared to a threshold. If the threshold is exceeded, a signal indicating a cardiac rhythm abnormality, such as fibrillation, is generated for triggering electrical therapy delivered to the cardiac tissue by the cardiac assist device.

Abstract: A magnetic field distribution measurement device (1) provides a non-contact magnetic field measurement on a subject's chest at a plurality of coordinates and forms therefrom time-series magnetic field distribution data. A first arithmetic device (2) in response generates image data representing a three-dimensional, intramyocardial current density distribution. A second arithmetic device (3) receives a plurality of tomographic image data separately obtained by a tomographic diagnosis apparatus and processes the data to generate three-dimensional, anatomical image data. A display device (4) receives these data and displays on an anatomical image an image representing an intramyocardial current density. This can facilitate identifying an anatomical, positional relationship of an abnormal, electrical reentry circuit caused in heart muscle. Furthermore, the anatomical image may be replaced with an image representing a normal stimulation propagation circuit and serving as a template.

Abstract: Systems, devices, structures, and methods are provided to present a visual display based on data from an implantable medical device. The display includes a chart showing the frequency of a detected type of arrhythmia over a predetermined period of time.

Abstract: An automated system and method for diagnosing and monitoring the outcomes of atrial fibrillation is described. A plurality of monitoring sets is retrieved from a database. Each of the monitoring sets include recorded measures relating to patient information recorded on a substantially continuous basis. A patient status change is determined in response to an atrial fibrillation diagnosis by comparing at least one recorded measure from each of the monitoring sets to at least one other recorded measure. Both recorded measures relate to the same type of patient information. Each patient status change is tested against an indicator threshold corresponding to the same type of patient information as the recorded measures which were compared. The indicator threshold corresponds to a quantifiable physiological measure of a pathophysiology resulting from atrial fibrillation.

Abstract: An atrial fibrillation monitor provides hand-contacting electrodes to allow daily ECG measurements of a patient without cumbersome electrode connection to the patient. ECG data may be diagnosed by the monitor to indicate likelihood of atrial fibrillation and an indication provided to the patient ECG data based on that indication may be forwarded to a physician or other healthcare professional for a review.

Abstract: A method and system for discrimination of supraventricular tachycardia and ventricular tachycardia events. Morphological features points are extracted from normal sinus rhythm (NSR) complexes and used to generate a NSR template. A numerical convolution is performed using the NSR template and the feature points for each sensed NSR to give a NSR filter output. Using a plurality of NSR complexes, a median NSR filter output template is determined, where the median NSR filter output template has a median value for each value in the NSR filter output. The median NSR filter output template is then used during a tachycardia event to distinguish tachycardia events as either ventricular tachycardia events or supraventricular tachycardia events.

Abstract: Thousands of patients prone to irregular and sometimes life threatening heart rhythms have miniature heart-monitoring devices, such as defibrillators and cardioverters, implanted in their chests. These devices detect onset of abnormal heart rhythms and automatically apply one or more shocks to their hearts. When properly sized and timed, the shocks restore normal heart function without human intervention. A critical part of these devices is the monitoring circuitry, which includes a microprocessor and stored instructions, or algorithms, that govern how the devices interpret and react to electrical signals indicative of abnormal heart rhythms. Often, the algorithms are too simple or too complex. Algorithms that are too simple lead to unnecessary shocking of the heart, while those that are too complex consume considerable battery power. Accordingly, the inventor devised a relatively simple and accurate algorithm for determining appropriate therapy options.

Abstract: An apparatus and method for detecting an atrial fibrillation through monitoring the R-R intervals of a patient's QRS complexes. Ratios of the current R-R interval are made to previous R-R intervals. Multiple moving averages are taken of the ratio results. The ratios are compared to a validating threshold and if the particular ratio is within a selected range, a moving average is calculated with inclusion of the present R-R interval. If the ratio is outside the range, a moving average is calculated without inclusion of the current R-R interval. The moving averages are combined and this difference average is compared to a trigger threshold. If the difference average exceeds the threshold, an atrial fibrillation is determined to exist, a memory trigger is provided, and the QRS complex data within a selected period of time about the atrial fibrillation event are recorded and removed from overwrite status in the memory.

Abstract: A method and apparatus for assessing the risk of atrial fibrillation in a patient by calculating the relative frequency of short and long intervals between successive heart beats during sinus rhythm is presented. An imbalance of short over long sinus intervals has been found to indicate a higher risk of atrial fibrillation. An implantable cardiac device may be configured to automatically deliver interventional therapy to restore sinus interval balance when such an imbalance is detected.

Abstract: By redistributing the running totals for various preliminary classifications to other preliminary classifications based upon the values of the most recent cardiac events, the present invention biases the running totals (thereby biasing the duration criteria) to help overcome common discrimination problems which permits the stimulation device to make a correct and final therapy decision more quickly. To identify a patient's heart rhythm, various electrical events such as P-waves and R-waves, and their timing, relationship, and stability, are detected and a preliminary classification is made for each detected event. Running totals of the numbers of all events detected within each of the preliminary classifications are maintained, along with sliding totals covering only the most recently detected events. Then, the arrhythmia is identified based upon an analysis of both the running totals and the sliding totals.

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: Devices and methods for testing a pulmonary vein to determine whether or not ablation would be effective in terminating atrial fibrillation. The devices and methods include a catheter having an expandable balloon attached to the distal end of the catheter. The balloon has pores on the distal end of the balloon for administering a fluid into the target pulmonary vein. The fluid inhibits the electrical impulses generated by the target pulmonary vein. Once the electrical impulses of the target pulmonary vein have been inhibited it can be determined whether or not the atrial fibrillation continues to occur. If the atrial fibrillation has been eliminated, then ablation or other therapy is appropriate. Thus, the devices and methods limit unnecessary treatment of a pulmonary vein.

Abstract: Detecting atrial and ventricular tachyarrhythmias involves classifying atrial interval rates in an atrial window having a first length and ventricular interval rates in a ventricular window having a second length. The second length of the ventricular window differs from the first length of the atrial window to enhance detection of ventricular arrhythmias relative to atrial arrhythmia detection. The atrial and ventricular interval rates in the respective windows are classified as fast or acceptable with respect to predefined thresholds. A ventricular episode is declared in response to satisfying the ventricular window according to a second satisfaction criterion. An atrial episode is declared in response to satisfying the atrial window according to a first satisfaction criterion.

Abstract: A system for on-line psycho-physiological profiling and support implementing a personalization engine operating in a plurality of network systems. An implanted medical device (IMD) in data communication with the personalization engine provides physiological, therapy and diagnostic data pertinent to the patient. Based on one or a combination of explicit, implicit and transactional input from the patient and in consideration of the IMD data underlying therewith, the patient is guided to consult with the most pertinent database.

Abstract: A system and method for treating atrial fibrillation using atrial pacing pulses to convert an atrial fibrillation to non-fibrillation atrial arrhythmia prior to delivering a low energy cardioversion/defibrillation shock. The system and method treats atrial fibrillations by first applying a plurality of pacing pulses to the atria which converts the atrial fibrillation to non-fibrillation atrial arrhythmia. Ventricular intervals are concurrently sensed and analyzed while the plurality of electrical pacing pulses are being applied. Upon detecting a period of stable ventricular intervals, the system then proceeds to deliver a low-energy cardioverting/defibrillating pulse of electrical energy across the atria of the heart.

Abstract: The present invention provides a method and apparatus for providing arrhythmia discrimination. Heart signals are monitored to determine when an arrhythmia state is being experienced by an individual. Once the arrhythmia state is detected, the heart of the patient is stimulated to produce stimulated heart signals. These stimulated signals are then monitored and compared with predetermined criteria in order to determine the type of arrhythmia being experienced as well as whether or not the arrhythmia requires treatment.

Abstract: An implantable medical device and method are provided for assessing autonomic tone and risk factors associated with arrhythmias and, based on this assessment, an early recurrence of ventricular tachycardia or ventricular fibrillation is predicted. Specifically, changes in R-R interval, heart rate variability, patient activity, and myocardial ischemia are measured prior to and after a detected an arrhythmia episode. A recurrence score is calculated as a weighted sum of measured parameters and compared to a prediction criterion. The prediction criterion may be a preset threshold score or an individualized episode template based on previously calculated recurrence scores associated with recurring episodes. Stored parameters and episode-related data may be downloaded for offline analyses for optimizing prediction criteria and monitoring patient status.

Abstract: A system and method for storing episodic data collected by an implantable medical device. If there are no unallocated storage locations, collected data associated with an episode is stored in locations that are freed from allocations to previous episodes. The least recently allocated of the storage locations allocated to episodes of a lower priority type may be freed first in order to maintain storage of higher priority episodic data. The method and system also allows a specified ratio of stored data allocated to episodes of one priority type to that of another priority type to be maintained.

Abstract: The invention is for a method for predicting an imminent episode of ventricular tachyarrhythmia by an analysis of the variations in the heart beat frequency during otherwise normal appearing sinus rhythm in the normal beat frequency range. The analysis is based on detecting a prolonged pattern of increasing heart beat rate. When the method is implemented by hardware it can initiate, or cause to be initiated, preventive therapies. A further implementation can cause the patient or attendant to be notified of imminent ventricular tachyarrhythmia. Both implantable and external devices are considered.

Abstract: An active implantable medical device, in particular a pacemaker, defibrillator and/or cardiovertor of the multisite type, capable of detecting an induced tachycardia. Such a device is to be coupled to electrodes placed in at least two cardiac sites of the same cardiac chamber type, e.g., at least two ventricular sites, right and left, at least two atrial sites, right and left, or at least two sites of the same cavity (atria or ventricular). The device has a cardiac signal collection circuit to detect a depolarization potential, and a stimulation circuit to apply stimulation pulses to at least certain of the aforesaid sites.

Abstract: An implantable cardiac stimulation device and method utilizes electrogram spectral analysis to administer electrical stimulation therapy to a heart to treat accelerated arrhythmias of the heart. The device includes an arrhythmia detector that initially detects an accelerated arrhythmia of the heart. An acquisition system then acquires an electrogram of the heart having both atrial and ventricular depolarization components. A processor then spectral analyzes the electrogram to provide spectral data related to the accelerated arrhythmia. The spectral data may be used for arrhythmia discrimination, arrhythmia tolerance discernment, and/or by a pulse generator to control stimulation therapy delivery timing.

Abstract: An animal model of atrial fibrillation and a method of identifying an animal exhibiting an atrial fibrillation phenotype. The method includes providing an animal having a minK (−/−) genotype; recording electrocardiograms from the animal over an extended time period; and identifying an atrial fibrillation pattern in the electrocardiograms to thereby identify the animal as exhibiting an atrial fibrillation phenotype. A method of screening candidate substances for activity in the treatment of atrial fibrillation using an animal model is also disclosed, as is a method of treating atrial fibrillation using a candidate compound identified as having activity in the treatment of atrial fibrillation.

Abstract: A method and apparatus are provided for improving the detection of certain cardiac rhythms by combining dual chamber interval-related detection methods with electrogram morphology analysis. A prioritized set of rules are defined wherein each rule is directed at identifying a particular arrhythmia or type of arrhythmia. Each rule includes clauses that may be related to sensed event intervals and interval patterns and at least one rule includes at least one clause relating to the EGM morphology.

Abstract: A method for monitoring the condition of a heart failure patient using respiration patterns is provided. An implantable or other ambulatory monitor senses the patient's respiratory patterns to identify the presence of periodic breathing or Cheyne-Stokes respiration. In a first embodiment, mechanical changes of the thorax due to breathing are detected and this data is used to recognize hyperventilation and apnea or hypoventilation. In a second embodiment of the invention, Cheyne-Stokes respiration is recognized by detecting changes in blood or tissue pH or CO2 concentration and partial pressure. In another embodiment of the invention, changes in pulse amplitude associated with Cheyne-Stokes respiration are detected. Alternating loss and return of respiration-induced amplitude modulation or pulse-interval variation may also be used to identify the presence of Cheyne-Stokes respiration.

Abstract: A method and apparatus are provided for differentiating among atrial-flutter, atrial-fibrillation and other cardiac rhythms. The method includes the steps of estimating a spectral entropy of atrial cardiac activity from an electrocardiogram of a patient and determining that the patient has atrial fibrillation when the spectral entropy is greater than a predetermined value.

Abstract: A system and method for discriminating cardiac rhythms occurring in an antegrade direction from cardiac rhythms occurring in a retrograde direction. Atrial and ventricular contractions are sensed, from which atrial and ventricular cycle lengths are determined. Ventricular contractions are also analyzed to determine the occurrence of a tachycardia episode that has a one-to-one association of atrial contractions to ventricular contractions. During a tachycardia episode having a one-to-one association of atrial contractions to ventricular contractions, the atrial cycle lengths are paired with the ventricular cycle lengths, where for each of the atrial cycle lengths the atrial cycle length is paired with at least one ventricular cycle length started before the first atrial contraction of each of the atrial cycle lengths and paired with at least one ventricular cycle length started after the first atrial contraction of each of the atrial cycle lengths.