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Biomedical subjects

G Flachenecker

Publications and source records attributed to G Flachenecker.

8 recordsLinked to original sources
PubMed1988

Ambulatory monitoring of the ST segment, using direct-recording Holter systems.

Direct-recording ambulatory electrocardiographic monitoring systems may produce serious errors not only because of their restricted bandwidth, but even more because of the "half-wavelength-to-head-contact effect." This article describes an easy measurement procedure and a mathematic model of the storage medium. The frequency response is calculated by way of five data from a single measurement. Some errors of typical recorders are discussed with the help of synthesized electrocardiographs. Measurements by six different recorders are listed.

Ambulatory Care↗
PubMed1988

[Silent myocardial ischemia in long-term ECG: is the standard of the American Heart Association for ST segment analysis adequate?].

Ambulatory ECG recording for ST-segment monitoring to detect episodes of silent ischemia has become of increasing clinical interest. Of the available Holter systems with different recording techniques, the direct recording (AM) systems are most commonly used. It still remains uncertain whether the recorded ECG signals are sufficient for the monitoring of transient ST-segment changes. A mathematical model was developed to allow a full description of a direct recording Holter system. As a representative, we used the Medilog I system which has been experimentally tested by Bragg-Remschel. Using the mathematical model, the ST-segment deformation was calculated at different heart rates for critical regions of the frequency response curve. Deviations of about +/- 30% occurred at different heart rates as compared to the original ST-segment signal. This is due to the half wavelength-to-head contact effect, inherent in direct recording systems. At present, ECG analysis for quantitation of ST-segment changes is already limited by upper and lower cutoff frequencies. In addition, system inherent amplitude and frequency of an induced sine wave need to be considered for correct measurements.

American Heart Association↗
PubMed1979

High frequency current effects during transurethral resection.

Transurethral resection has been simulated electrically to detect the current pathways and locations of heat production inside the patient. Different electrical behavior was noted with instruments using electrically insulated or metal sheaths. Conductive lubricating jelly should be used with the metal sheath and non-conducting jelly should be used with the insulated sheath.

Electric Conductivity↗
PubMed1977

[Capacitive effects during transurethral resections with high-frequency currents (author's transl)].

The cutting probe of transurethral resection devices has to be fed through a line inside of the shaft. The capacitive high-frequency currents between this feeder and the shaft flow through the urethra and may cause destructive heat within the urethra if a metallic shaft is used. This paper shows that no danger is caused from these capacitive currents as long as the capacity between feeder and shaft is less than 120 pF.

Electric Injuries↗
PubMed1977

[The significance of the characteristics of lubricating jellies in use during transurethral prostate resections with metallic sheaths (author's transl)].

If a metallic sheath is used during a transurethral resection of the prostate with high-frequency currents, the lubricating jelly has to exceed a prescribed conductivity, in order to prevent dangerous current-density spots within the urethra. Furthermore, the mechanical behaviour of the lubricating jelly and the mode of its application have to be considered carefully.

Burns, Electric↗