Medtronic, Inc.

Peter M Van Dam

Mattias Rouw

Willem Boute

Gustaaf A P Stoop

Joanneke Gerrigje Groen

Geeske Van Oort

Peter W Wohlgemuth

Peter Oosterhoff

Diederick M Keizer

Josephus P A Smit

Jos P A Smit

Suzanne Mouton

Gustaaf AP Stoop

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. When a cardiac rate exceeds a predetermined threshold, the implantable medical device modifies the pacing protocol parameters to promote AV synchrony.

Implantable medical device with ventricular pacing management of elevated heart rates

There is provided an implantable cardiac pacing system or other cardiac monitoring system having an enhanced capability to classify intracardiac signals through a combination of DSP techniques and software algorithms. The implantable device has one or more DSP channels corresponding to different signals which are being monitored. Each DSP channel most preferably amplifies the incoming signal, converts the signal from analog to digital form, digitally filters the converted signals to provide a filtered signal, operates on the filtered signal to provide a slope signal, determines from the filtered and slope signals when an intracardiac event has been detected, signal processes the filtered and slope signals for a predetermined analysis interval after threshold crossing, and generates a plurality of wave parameters corresponding to the signal. The generated wave parameters are further operated on by a programmable algorithm to classify the detected event based upon DSP-generated parameters, and then monitor or detect the onset, development or presence of an undesired heart condition in a patient. The system may further provide for the delivery of treatment, storage of intracardiac data, or provision of a warning to a patient or physician in response to the detection of such a heart condition.

Cardiac pacing system with improved physiological event classification and heart monitoring based on DSP

A method of classifying arrhythmias using scatter plot analysis to define a measure of variability of a cardiac rhythm parameter such as for example, without limitation, R-R interval, A-A interval, and the slope of a portion of a cardiac signal, is disclosed. The variability measurement is derived from a scatter plot of a cardiac rhythm parameter, employing a region counting technique that quantifies the variability of the cardiac rhythm parameter while minimizing the computational complexity. The method may be employed by an implantable medical device or system, such as an implantable pacemaker or cardioverter defibrillator, or by an external device or system, such as a programmer or computer. The variability measurement may be correlated with other device or system information to differentiate between atrial flutter and atrial fibrillation, for example. The variability information may also be used by the device or system to select an appropriate therapy for a patient.

Method of and apparatus for classifying arrhythmias using scatter plot analysis

An implantable medical device and associated method perform ECG morphology monitoring. A subcutaneous ECG signal and a posture signal are sensed in a patient. A cardiac condition is detected in response to the ECG signal and the posture signal. In one embodiment, multiple ECG morphology templates corresponding to each of a number of different patient postures are acquired and stored for use in detecting a cardiac condition.

Template matching method for monitoring of ECG morphology changes

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device determines a course of action based upon the presence or absence of sensed ventricular activity. The device further determines whether that activity is properly conducted or the result of a PVC or nodal rhythm.

Implantable medical device with ventricular pacing protocol

Systems and methods for distinguishing a valid sensed cardiac signal from an invalid signal, such as a myopotential. In one embodiment, sensing an electrical signal with one electrode causes a timing window to commence. When the electrical signal is sensed by another electrode in the timing window, the sense is deemed valid. When the electrical signal is not sensed by the other electrode in the timing window, the sense is deemed invalid. Therapy may be adjusted when an inordinate number of senses are invalid.

Distinguishing valid and invalid cardiac senses

There is provided a system and method of rate responsive pacing, having an intrinsic QT rate sensor. The system has the capability of sensing the QT interval of intrinsic cardiac signals and constructing from such intrinsic QT data a QT reference curve. The QT reference curve is used for comparison with beat-to-beat QT interval data, in order to provide sensor information for controlling pacing rate. The system of this invention preferably utilizes DSP circuitry for determining the occurrence of a Twave event and the timing of the Twave, from which the QT interval is calculated. The system also provides for compensation of any QT interval which is calculated following ventricular pacing, so that the QT sensor is operative at all times and throughout the entire rate range experienced by the patient. The system thereby provides an enhanced QT rate responsive pacing arrangement, and avoids the need of overdrive pacing in order to obtain QT reference data.

Rate responsive pacing system with QT sensor based on intrinsic QT data

The invention presents a medical device system and method for determining the degree of heart failure of a patient, utilizing information representative of dynamic variations in patient QT, or segments of QT, over time. The dynamic variations in QT that are measured relate to characteristics of the variation of QT with rate when rate is increasing and when it is decreasing. The dynamic variations include QT dynamic range, QT hysteresis, and QT directrix, each providing important information relating to the patient's variation of QT with heart rate, or QT(RR). QT and dynamic variations of QT can be measured in both left and right ventricles, and taken over the patient's normal rate range. The dynamic data is measured and stored periodically and compared with historical data to determine progression toward heart failure. In another embodiment, the QRST signals are divided into segments, namely QRS width; ST segment; and T wave width, and variations of these segments are analyzed to provide additional information indicative of the patient's heart condition. Preferably the system utilizes a microprocessor programmed to carry out an algorithm that weighs detected variations in QT, QT segments and/or QT dynamic parameters with time to track cardiac changes.

Pacemaker utilizing QT dynamics to diagnose heart failure

There is provided a system for regulating ventricular rate in the presence of abnormally high atrial rates, e.g., during episodes of atrial fibrillation. During such an episode, the system, preferably incorporated into an implantable pacemaker, applies subthreshold bursts of stimulus pulses to or proximate to the patient's AV node so as to inhibit conduction of electrical signals through to the ventricle during the bursts. The bursts are timed in relation to the last conducted ventricular signal, and in terms of burst length, to provide a rate of conducted signals through the AV node which results in a substantially regular and reduced ventricular rate. During the inhibition mode of operation, the system monitors to determine the efficacy of inhibition, by tracking the percentage of ventricular senses that occur during the burst periods. When inhibition is found to be below an acceptable percentage, the system carries out an inhibition test and re-adjusts the burst parameters to provide bursts of optimized stimulation energy.

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Doesburg, Netherlands

Peter M Van Dam