C-THV measures of self-expandable valve positioning and correlation with implant outcomes.

BACKGROUND: Accurate positioning of the valve device during transcutaneous aortic valve implantation (TAVI) is of crucial importance. The Paieon C-THV navigation system has been designed to correctly guide device deployment during TAVI. OBJECTIVES: Using this navigation system we aimed to determine the correlation between the anatomic measures of the native aortic valve and the deployed self-expandable valve positioning and to explore the impact upon procedural outcomes. METHODS: We analyzed data of 68 patients with severe symptomatic aortic stenosis undergoing TAVI, using the catheter-based Medtronic-CoreValve self-expandable system. Patients were subdivided into two groups according to whether the C-THV system was used (50) or not (18) during the implantation process. Analysis of geometrical outcomes vs. clinical outcomes including postprocedural electrical conduction defect and/or para-valvular leaks was performed. RESULTS: Taking the target implantation line as a reference; relatively lower vs. higher implantations correlated with a higher frequency of any new onset electrical conduction defect (ECD). The mean corresponding distance from valve inferior edge below the virtual aortic annulus line was 3.0 ± 1.6 mm vs. 1.2 ± 1.3 mm in patients with (38.5%) vs. without any new onset ECD, respectively (P = 0.05). The use of C-THV navigation seemed to correlate with higher valve implants but it had no impact on the occurrence of postprocedural paravalvular leaks. CONCLUSIONS: Self-expandable valve implants guided by C-THV navigation seems to be associated with more precise implants and lower risk for postprocedural electrical conduction defects, due to higher location in relation to the target line.

Cardiac spiral wave drifting due to spatial temperature gradients - A numerical study.

Cardiac rotors are believed to be a major driver source of persistent atrial fibrillation (AF), and their spatiotemporal characterization is essential for successful ablation procedures. However, electrograms guided ablation have not been proven to have benefit over empirical ablation thus far, and there is a strong need of improving the localization of cardiac arrhythmogenic targets for ablation. A new approach for characterize rotors is proposed that is based on induced spatial temperature gradients (STGs), and investigated by theoretical study using numerical simulations. We hypothesize that such gradients will cause rotor drifting due to induced spatial heterogeneity in excitability, so that rotors could be driven towards the ablating probe. Numerical simulations were conducted in single cell and 2D atrial models using AF remodeled kinetics. STGs were applied either linearly on the entire tissue or as a small local perturbation, and the major ion channel rate constants were adjusted following Arrhenius equation. In the AF-remodeled single cell, recovery time increased exponentially with decreasing temperatures, despite the marginal effect of temperature on the action potential duration. In 2D models, spiral waves drifted with drifting velocity components affected by both temperature gradient direction and the spiral wave rotation direction. Overall, spiral waves drifted towards the colder tissue region associated with global minimum of excitability. A local perturbation with a temperature of T = 28 °C was found optimal for spiral wave attraction for the studied conditions. This work provides a preliminary proof-of-concept for a potential prospective technique for rotor attraction. We envision that the insights from this study will be utilize in the future in the design of a new methodology for AF characterization and termination during ablation procedures.

Medical iPad use in the cardiac catheterization and echo laboratories.

The present study aims to describe a dedicated cardiac imaging application on a tablet and to assess the accuracy and reproducibility of this novel application for measurement on angiography and echocardiography data sets. Tablet devices have recently been used in radiological image interpretation and enable transfer of images. It allows the clinician to look up clinical information, search the Internet and communicate with colleagues and family. The study group consisted of 30 patients who had both echocardiographic and angiographic examinations. For each patient, a few measurements (i.e. length, area and angle) were performed using the iPad, and compared to the McKesson workstation, which is routinely used in the hospital. In order to show the equivalence between these two methods, a linear regression was fitted and the distribution of differences between measurements was examined. In addition, the variability of the measurements was compared between two different reviewers (inter-observer test) and between the measurements of the same reviewer at two different time settings (intra-observer test) by calculating the intraclass correlation coefficient (ICC). In all comparisons, the linear regression showed high correlation coefficient (r > 0.9), and the distribution of differences was around zero, implying that the two methods lead to equivalent results. The absolute mean difference between the two different observers demonstrated high agreement between the two observers' repeated measurements. The same conclusions can be deduced from the same observer's repeated measurements. The ICC indicates the resemblance between the two sets, and could be considered almost perfect (ICC > 0.968 for all cases). The newly developed cardiology iPad application offers the opportunity to accurately present the cardiac procedure in a visual, clear and professional manner.

Hemorrhage control of liver injury by short electrical pulses.

Trauma is a leading cause of death among young individuals globally and uncontrolled hemorrhage is the leading cause of preventable death. Controlling hemorrhage from a solid organ is often very challenging in military as well as civilian setting. Recent studies demonstrated reversible vasoconstriction and irreversible thrombosis following application of microseconds-long electrical pulses. The current paper describes for the first time reduction in bleeding from the injured liver in rat and rabbit model in-vivo. We applied short (25 and 50 µs) electrical pulses of 1250 V/cm to rats and rabbit liver following induction of standardized penetrating injury and measured the amount of bleeding into the abdominal cavity one hour post injury. We found a 60 and 36 percent reduction in blood volume in rats treated by 25 µs and 50 µs, respectively (P<0.001). Similar results were found for the rabbit model. Finite element simulation revealed that the effect was likely non-thermal. Histological evaluation found local cellular injury with intravascular thrombosis. Further research should be done to fully explore the mechanism of action and the potential use of short electric pulses for hemorrhage control.