Method and apparatus for storing signals in an implantable medical device

Abstract

A method of storing signals having a course over time in an implantable medical device, and / or transmitting the signals out of the device and out of the patient's body, with the course over time being detected in the device, particularly at predetermined time intervals with a constant sampling interval, and a sequence of signal samples being obtained therefrom, of which a partial quantity is stored and / or transmitted as the result of a selection made with a predetermined selection criterion, with the selection criterion being the first derivation of the course over time of the signals according to time, and with the selection being made such that the first derivation of the straight-line connection between an nth and the (n−1)th signal sample is determined and compared to the first derivation of the straight-line connection between the (n−1)thnth signal sample and the last-stored and / or last-transmitted signal sample, and the nth(n−1)th signal sample is then stored and / or transmitted as the new last signal sample exactly when these first derivations differ by more than a predetermined value.

Description

BACKGROUND OF THE INVENTIONThe invention relates to a method of storing signals having a course over time in an implantable medical device, and / or transmitting the signals out of the device and out of the patient's body, with the course over time being detected in the device, particularly at predetermined time intervals with a constant sampling interval, and a quantity of signal samples being obtained therefrom, of which a partial quantity is stored and / or transmitted as the result of a selection made with a predetermined selection criterion, and an apparatus for executing the method.The detection and evaluation of physiologically-relevant signals in the body with suitable detection or monitoring devices are in step with the continuously-expanding use of implantable medical devices such as cardiac pacemakers or defibrillators. The operation of the implantable device is controlled on the basis of the results of, for example, the detection and evaluation of the course over time of car...

AI Technical Summary

Benefits of technology

It is an object of the invention to disclose a method of the generic type described at the outset, and an apparatus for executing the method, that permit processing of the (physiological) signals detected with an implantable medical device for reliably controlling the device, and / or for diagnostic purposes, with a comparatively low storage and processing outlay and current consumption.

In these connections, the method permits a considerable increase in the control intelligence of implanted pacemakers, defibrillators, cardioverters or medication-dosing devices, based on significantly-expanded possibilities, to a true signal-form processing in addition to standard processing of singular, logical or scalar measurement and comparison variables.

The method permits a time-near transmission of the detected and compromised data without costly buffer storage of comprehensive data sets. Because the method requires a reference to the last signal sample that was accessed as being worth storing or transmitting, in the case of time-near transmission at least the last-transmittal signal sample is to be held in internal intermediate storage.

The method can be implemented particularly simply and cost-effectively with the hardware used in modern defibrillators and pacemakers if the sampling is connected to a digitization of the amplitude values; it is particularly advantageous for adequate storage and further evaluation, especially of cardiac signals, if the digitizing of smaller amplitude values is effected with higher resolution than that of large amplitude values.

Problems solved by technology

These techniques have not yet been able to gain a foothold in the field of storage and transmission of physiological data, particularly in implantable devices, partly because of the high cost of the device technology and partly because of the specifics of the signals occurring here and the information to be obtained over the course of the signal processing.

The system only serves in a first screening as the precursor of the later, more precise detection of arrhythmia states, and is not suited for obtaining precise diagnostic information, and is especially ill-suited for controlling implanted devices.

If this method is intended to effect a resolution that permits the reliable, autonomous control of a combination anti-arrhythmia device, a large amount of storage space is required for storing the precise times at which the signal changes occur, and the time-data conditioning for the actual (particularly comparative) evaluation requires a substantial outlay.

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