Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2001-05-22
2003-05-13
Getzow, Scott M. (Department: 3762)
Surgery
Diagnostic testing
Cardiovascular
C607S009000
Reexamination Certificate
active
06564091
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to storing cardiac rhythm information.
BACKGROUND OF THE INVENTION
The most precise possible detection of cardiac rhythm information over sufficiently long periods of time and, if possible, in various physical and psychical situations of a patient, is—as has been known for a long time—an indispensable diagnostic aid for the cardiologist. In particular, monitoring of the temporal developments in the intervals between atrial events (the so-called PP intervals), as well as between ventricular actions(in particular the so-called RR intervals), as well as the time intervals between subsequent atrial and ventricular actions (of the PR intervals) or between ventricular and atrial actions (of the RP intervals), allows valuable conclusions as to specific arrythmiae.
Whereas in the out-patient and clinical practice of the cardiologist, the detection and recording of cardiac rhythm information is carried out, as a rule, by means of high-resolution ECG devices detecting as many details as possible so as to furnish to the physician valuable wave-shape data of the cardiac signals apart from the above-mentioned time intervals, the cardiac rhythm data detected on a patient over a certain period of time has to be processed and stored with a lowest possible expenditure in processing capacity and storage space for certain important applications. This requirement exists in particular with implanted cardiological devices which have been known and practically used for a prolonged period of time in the form of heart pacemakers for the treatment of bradycardia and/or tachycardia arrythmiae, as well as automatic defibrillators or cardioverters, or also as combined pacemakers/cardioverters or implanted drug dosing pumps.
Highly developed devices of this kind namely are equipped with one sensor or several sensors for detecting diagnostically relevant cardiac rhythm information in the patient's body, and with associated signal shaping and processing steps, as well as an evaluation and control unit making a selection between a number of pre-programmed operation parameters or therapy variants, and therapy parameters with dependence on the detected cardiac rhythm information, according to an algorithm stored in the device. In particular, stimulation devices count among these which are automatically activated or switched from one mode to another, depending on the detected cardiac state of the patient. Thus, with certain types of automatic implantable defibrillators and antitachycardia pacemakers, a continuous detection of the time intervals between atrial actions and/or ventricular actions is carried out over a sufficiently long period of time, so as to be able to recognize life-endangering acceleration of the cardiac rhythm as early as at its initial stage, and to respond thereto by means of an appropriate stimulation therapy.
So as to be able to reliably detect the mentioned life-endangering states (in particular atrial or ventricular fibrillation) in the various known signs of disease, on the occasion of which the mentioned automatic cardiac rhythm correction means are used, detection and storing must extend over a considerable period of time or a considerable number of cardiac actions.
Even when only the time intervals between the P and/or R waves of the heart signal are detected and stored, and the detection, processing and storage of wave-shape data is completely renounced of, a considerable processor and storage capacity will be required for this purpose in the implanted device. This is of less importance with respect to the costs of the processors and memory modules which, as a matter of course, become higher with increased capacity demand. Rather, it is of importance with respect to the power consumption and therewith, the lifetime of the battery. Despite considerable progress in primary cell technology and corresponding capacity enhancements of the lithium cells used in implanted devices, the power consumption for processing and storing the time intervals between heart actions leads to an essential decrease in the battery life, and therewith of the device lifetime in known heart pacemakers,
Previously, several proposals have been made for compression methods which were specifically provided for a preprocessing of ECG information prior to processing or storing or, it general, for signal compression for implantable battery-operated devices.
Thus, in EP 0 263 599 A2, an ECG data compression is so proposed that a time marker is stored whenever the amplitude of the ECG input signal has changed by a certain amount as compared to the preceding recording date. In addition, art identification marker is stored upon a change of the sign of the increase of the ECG signal.
In EP 0 526 973 B1, the averaging for cardiac signals by means of a combined use of a temporal data compression and a sampling correlation is described,
In U.S. Pat. No. 5,724,032, a method and an apparatus for compressing and displaying the cardiac rate within the scope of a fetal cardiac rhythm monitoring are described. This solution is based on the principle of the “maximum absolute difference”, i.e. the data sampled within a certain interval are compared with an initial value, and the value having the highest absolute difference as compared to the initial value is selected and stored as a representation of the data sampled in said interval. This method is directed to a high degree of maintenance of highly frequent signal components which are valuable within the scope of clinical diagnosis.
In EP 0 540 144 B1, a method and an apparatus for ECG data compression are described, wherein the RR time intervals between subsequent ventricular actions along with sampling values obtained at certain intermediate moments of time are stored. Hereby, a reconstruction of the shape of the R waves becomes possible.
From the Applicant's DE 196 99 41 C2, a method and at device are known for storing signals in an implantable medical device, in particular for a compressed storing of ECG signal shape information. Hereby, the temporal signal course is sampled at predetermined time intervals and a subset of the sampling points is stored which is selected by means of a selection criterion—specifically the first differentiation of the temporal signal course as per time.
From EP 0 884 851 A2, a system and a method for data compression and for a non-linear sampling for implantable battery-operated devices are known which are also provided for an implantable pacemaker. The method resides essentially in the generation of a time-variable threshold value signal by means of which the physiological (analog) signal is compared with certain clock intervals. Hereby, a non-linear sampling is caused, and the thereby obtained data is finally subjected to a further compression.
From I. Provaznik, J. Kozumplik, “Wavelet transform in electrocardiography-data compression” Int. J. Med. Inf. 45 (1997), 111, an imaging diagnostic method on the basis of the Run-Length Encoding principle is known that is based on the decomposition of the ECG signal into a set of basic functions which completely cover the time-frequency domain. This method, as well as other, similar methods, is provided for ECG processing and recording in the out-patient and clinical area.
From U.S. Pat. No. 5,709,216, it is known to realize a data reduction of the measured values sampled in an implantable medical device by means of a method for variably resolving a data reduction, so as to reduce the storage space required. Hereby, for example, cardiac action intervals being physiological data, are converted into a digital value, whereby the digital representation is divided into portions, and individual subportions are allocated various resolution values.
From U.S. Pat. No. 5,819,740, a system and a method for compressing digitalized signals in implantable battery-fed devices are provided, by means of which especially an efficient telemetric transmission to an external receiver is supposed to be secured. In this solution, the method of determining a delta value or
Biotronik Mess-und Therapiegerate GmbH & Co. Ingenieurburo Berli
Getzow Scott M.
Kinberg Robert
Venable LLP.
LandOfFree
Method and memory means for storing cardiac rhythm information does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and memory means for storing cardiac rhythm information, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and memory means for storing cardiac rhythm information will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3021630