Citations

Background/Objectives: Radiofrequency (RF) wire energy can be used for tissue ablation across many conditions. Adjusting RF generator parameters allows RF energy to puncture tissue with minimal adjacent damage. When RF energy is applied to tissue, however, microbubbles are produced, obstructing intravascular ultrasound (IVUS). Mitigation of RF-generated microbubbles has been studied for ablation but not for puncture. Methods: This paper describes an in vitro bench study using ex vivo bovine live tissue. A model was created with bovine liver tissue and an IVUS catheter submerged in a saline bath. Tissue was punctured with an RF guidewire to recreate microbubbles. Following the puncture, various methods were applied: altering the mechanical index of the IVUS, applying a VF10-5 Linear probe (Siemens), and applying a L12-3 Linear probe (Philips). Regions of interest (ROIs) were selected to track pixel brightness as a proxy for microbubbles. Results: The control increased ROI brightness by 1.5%. Altering the mechanical index of IVUS reduced ROI brightness by 1.2%. VF10-5 probe application increased ROI brightness by 1.2%. L12-3 probe application reduced ROI brightness by 33.0% (p = 0.046, n = 3, one-sample t-test). Brightness reduction was most pronounced at the site of initial RF wire puncture, where microbubbles accumulated. Tip visualization improved, allowing for more precise wire trajectory adjustments. Conclusions: External US with an L12-3 probe was able to dissipate microbubbles effectively to improve IVUS guidance following RF wire puncture in an in vitro exploratory bench model.

Abstract Aims This study aimed to establish 2D and M-mode echocardiographic reference values for cardiac chambers, outflow tracts, and great vessels for school children living at high altitudes, differentiated between males and females. Methods and results This post hoc analysis included children with normal echocardiography from a cluster randomized cross-sectional survey of rheumatic heart disease among school children in Peru. The echocardiograms were acquired with a portable machine and the images were analysed centrally with a standardized methodology. Body surface area (BSA) was used as an independent variable to predict the mean values of echocardiographic measurements for both male and female groups. Reference values are presented on z-scores and nomograms based on sex. Propensity score matching was used to compare sexes. A total of 985 students aged 5–16 years were included. The Haycock formula provided the best fit and was used when presenting data as predicted values for a given BSA. The z-score and nomograms for all essential parameters of cardiac chambers, great vessels, and functional surrogates are presented based on sex. The majority of the parameters were significantly different per sex after propensity score matching. Conclusion Normal reference values and nomograms of cardiac chambers, outflow tracts, and great arteries in healthy school children living at high altitudes based on sex were reported. These data partly addressed the existing gaps in paediatric echocardiographic nomograms.