Tissue Tracking Imaging for Identifying the Origin of Idiopathic Ventricular Arrhythmias: A New Role of Cardiac Ultrasound in Electrophysiology

Several strategies for mapping ventricular outflow tract tachycardia have been reported as useful indices for differentiating between those originating from the right and the left side. Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an ultrasonographic technique that measures the myocardial motion amplitude towards the transducer in each region during systole, identifying regional myocardial displacement on the basis of myocardial velocities using color Doppler myocardial imaging principles. In this technique, the origin of the arrhythmia could be recognized as the site where the earliest color-coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary studies this modality was found to be useful in differentiating out flow tract ventricular tachycardias. ECCS was always found below or at the level of the pulmonary valve in all arrhythmias which could be ablated from the right ventricular outflow tract, while in those where the origin was above the pulmonary valve could be ablated from the left sinus of valsalva. These results indicate that TTI can provide detailed and accurate information on the arrhythmia origin of OT-VT and may be useful for differentiating between an OT-VT originating from the LV epicardium remote from the LSV and that from the LSV. Newer advances in echocardiographic technologies like high resolution, high frame rate real time three dimensional echocardiography with speckle tracking may further improve the precise localization of arrhythmias in the future

Tunable thermochromic properties of V 2 O 5 coatings

Thermochromic Di vanadium pentaoxide (V2O5) coatings displaying a variety of colours were synthesised. Tuning of thermochromic behaviour was achieved via a controlled oxidative annealing under ambient air of the as-grown VOx films. Adjusting the oxygen deficiency in V2O5, allows tuning the colour of the films and as a consequence its thermochromic behaviour. Non oxygen deficient V2O5 did not feature any measurable thermochromis

Light modulation in phase change disordered metamaterial - A smart cermet concept

Cermet coatings are popular solar selective absorbers as they allow capturing most of the solar energy while minimising radiative losses. Embedded metallic nanoparticles in dielectric matrices promote multiple internal reflection of light and provide an overall low emissivity. VO2 in the metamaterial state is regarded in this study as a responsive mixed phase comprising metallic rutile VO2 inclusions in semiconducting monoclinic VO2 phase mimicking cermet. The smart cermet responds to thermal stimuli by modulating the size of the metallic inclusions and thereby enabling the manipulation of their interaction with light. The highly reliable and reproducible response of the smart cermet corroborates with the observed ramp reversal memory effect in VO2. We demonstrate a thermally controlled 85% emissivity switch taking advantage of the narrow hysteresis and tuning abilities of the disordered metamaterial

Vanadium Oxide as a Key Constituent in Reconfigurable Metamaterials

Tunable materials are paving the way towards improved functionality of metamaterials. Vanadium oxide (VO2) with its prototypical near-room-temperature transition between phases featuring greatly contrasting electrical and optical behavior is an appealing candidate as an active component in metamaterials. However, it is seldom known that VO2 in itself has metamaterial characteristics. VO2 under certain temperature conditions demonstrates a phase coexistence enabling highly tunable electrical and optical properties. In this chapter, we describe how VO2 in its hysteretic region behaves as a smart responsive Metasurface with cutting edge applications