Biomedical subjects

A Hedjiedj

Publications and source records attributed to A Hedjiedj.

4 recordsLinked to original sources

PubMed2006

The behavior of dual-chamber pacemakers exposed to a conducted low-frequency disruptive signal.

This paper presents a study of the behavior of dual-chamber cardiac pacemakers submitted to low-frequency conducted disruptions. The disruptive signal is sinusoidal, operating at 50 Hz, 60 Hz, 10 kHz and 25 kHz. The behavior of the pacemakers is described by statistical data obtained with a telemetry system and by visualization of the pacemaker signal during the application of the interfering signal. The pacemakers were tested in two configurations. The first one consists of direct application of the interfering signal between the pacemaker terminals. In the second, these attempts are completed by in vitro tests using an electromagnetic model which allow us to take into account the interface which constitutes the human body. The pacemaker under test is inserted into a gelatine phantom mimicking the electrical conductivity of tissues. This study allowed us to define the pacemaker detection thresholds for the two test configurations. For the in vitro approach, which constitutes a complementary approach to a realistic implantation situation, oversensing is noticed for 10 kHz and 25 kHz interfering signal frequencies. Detection thresholds vary from a few tens to a few hundreds of mV, depending on the interfering signal frequency, the device and its programmed detection sensitivities.

Data Interpretation, Statistical↗

PubMed2003

[Relevance of in vitro studies for the immunity of cardiac implants in an electromagnetic field environment]].

The object of this article is to show the contribution of the vitro experimental approach, based on the basic rules of electromagnetic compatibility (EMC), as a complementary tool to the clinical studies. Results can be obtained by a experimental approach in vitro with electromagnetic phantoms associated to a bench of "standard" test to allow a possible comparison between various studies. After describing the protocol developed for the cardiac implants (pacemakers and defibrillators), examples of partial results are presented by way of illustration.

Defibrillators, Implantable↗

PubMed1995

Intracardiac high-frequency catheter ablatherapy: technical aspects.

Arrhythmia and conduction disorders can be treated by intracardiac ablation. The paper presents an original intracardiac catheter ablation method using a high-frequency (HF) electromagnetic power source. A high-frequency signal is emitted through an electrophysiological catheter introduced into the femoral vein and passed along the course of that vein into the heart. To prevent impedance rise, a problem encountered with other techniques, HF signal wave trains are used for half-period impedance match control and, where necessary, automatic impedance adjustment. Fully automated impedance matching combined with frequency-specific catheter design prevents power reflection between load and source. Resulting lesions can be controlled as to location, area and depth. In addition, HF pulses can be released independently of cardiac rhythm. Additional comprehensive animal experimentation is currently going forward.

Animals↗

PubMedDate not supplied

A methodological approach for the characterization of cardiac pacemaker immunity to low frequency interferences: case of 50 Hz, 60 Hz, 10 kHz and 25 kHz led disruptions.

The goal of this work is the implementation of a metrological set up dedicated to the characterization of cardiac pacemakers' immunity at low frequency electromagnetic disruptions. The studied frequencies are 50 Hz, 60 Hz, 10 kHz and 25 kHz. The assessment methodology that is applied is in accord with the electromagnetic compatibility. The tests are carried out on single-chamber pacemakers. The first approach, consisting of the application of the interfering signal directly between the housing and the electrode, enabled us to point out the influence of a preset detection sensitivity on the signal levels induced between the terminal and the pacemaker's housing. These attempts are completed by in vitro tests using an electromagnetic model which allows one to take into account the interface which constitutes the human body, and thus to get closer to a real life situation. The visualization of the pacemaker generated signal illustrates the performance of the pacemaker according to different test configurations. It is an initial approach meant to create a base for the creation of a metrological protocol.

Electromagnetic Fields↗