Compatibility of transvenous implantable cardioverter defibrillator and vagus nerve stimulation device: a case report.

Background: Vagus nerve stimulation (VNS) is an established therapy for drug-resistant epilepsy and depression. While VNS co-existence with cardiac pacemakers is considered safe, its interaction with implantable cardioverter defibrillators (ICDs) remains poorly understood. The concern revolves around the potential for VNS stimulation to interfere with ICD function, potentially resulting in inappropriate therapy or changes in cardiac pacing. Case summary: We present the case of a 50-year-old woman with drug-resistant epilepsy who underwent VNS device implantation and subsequent transvenous ICD placement for primary prevention post-myocardial infarction. These devices were thoughtfully situated contralaterally, with a minimum 10 cm separation. Comprehensive testing and follow-up demonstrated no interactions during device programming or serial assessments. Simultaneous interrogation of both devices with their respective telemetry wands caused chaotic artefacts in all channels on the ICD, likely due to electromagnetic interference. Importantly, this interference did not affect ICD sensing. Discussion: The co-existence of VNS and ICD in a patient is an emerging scenario with limited previous reports, yet our findings align with prior cases involving VNS and pacemakers. Emphasizing the need for optimal device separation and meticulous evaluation, particularly at maximum VNS output and ICD sensitivity settings, ensures their safe and feasible co-existence. As the use of VNS alongside cardiac implantable electronic devices becomes more common, a diligent evaluation for potential interactions is imperative. Our case highlights the successful co-existence of VNS and ICD, underscoring the importance of careful monitoring and evaluation to guarantee the safe utilization of these two devices.

Iatrogenic pacemaker-induced ventricular arrhythmia: a case report.

Background: Minimizing right ventricular (RV) pacing to reduce the progression of heart failure is an established practice. Proprietary algorithms to reduce unnecessary RV pacing have been incorporated into both simple and complex cardiac pacemaker devices, for reducing the possibility of heart failure and arrhythmias. Case summary: We present a case of a 43-year-old male implanted with a dual-chamber primary prevention implantable cardioverter-defibrillator (AUTOGEN EL, Boston Scientific) for sudden cardiac death. At the time of implant, the patient had hypertrophic cardiomyopathy with mild left ventricular (LV) systolic impairment, and sinus rhythm with intact atrioventricular (AV) conduction. The patient developed progression of his disease with symptoms (dyspnoea) and LV impairment. This led to a decision to activate the minimal RV pacing algorithm (RYTHMIQ™). A deterioration in AV conduction caused intrinsic ventricular beats to fall in the atrial blanking period, and subsequent VVI backup pacing resulted in R on T pacing. This induced ventricular arrhythmia. RYTHMIQ™ was subsequently deactivated, and the patient has had no further device-induced arrhythmias. Discussion: Numerous studies have demonstrated the adverse effect of RV pacing on LV function. Minimizing RV pacing is, therefore, encouraged in individuals with intact AV conduction. However, underlying conduction abnormalities must be assessed prior to activating algorithms designed to minimize RV pacing. This case demonstrates the importance of careful intracardiac electrogram interpretation and individual case-based device programming, to avoid device-induced complications.

Optically tunable silicon photonic crystal microcavities.

We demonstrate the use of silicon photonic crystal based microcavity structures to perform light modulation at potentially giga-Hertz speeds through the use of optically induced plasma dispersion. The cavity configurations considered have the potential to operate at low pump power when the Q of the cavity involved is maximized.

All-optical switching in silicon photonic crystal waveguides by use of the plasma dispersion effect.

Silicon photonic crystals offer new ways of controlling the propagation of light as well as new tools for the realization of high-density optical integration on monolithic substrates. However, silicon does not possess the strong nonlinearities that are commonly used in the dynamic control of optical devices. Such dynamic control is nevertheless essential if silicon is to provide the higher levels of functionality that are required for optical integration. We demonstrate that the combination of the refractive index change caused by the presence of photoexcited carriers, or so-called plasma dispersion, and photonic crystal properties such as photonic bandgaps, constitutes a powerful tool for active control of light in silicon integrated devices. We show close to 100% modulation depth near the photonic crystal band edge.