Anatomical reconstructions of the human cardiac venous system using contrast-computed tomography of perfusion-fixed specimens

Virtual Reality-based Methods for Training Novice Electrophysiology Trainees-A Pilot Study

Developing an accurate and detailed 3-dimensional (3D) mental model of cardiac anatomy is critical for electrophysiology (EP) trainees. Due to its immersive nature, virtual reality (VR) may provide a better learning environment than traditional teaching methods for assimilating 3D cardiac anatomy. The purpose of this pilot study was to evaluate the technical feasibility of an interactive, remote VR-based method for teaching cardiac anatomy to novice EP trainees. We created a shared, remote VR environment that allows the shared viewing of high-resolution 3D cardiac models. Eighteen trainees accepted for pediatric and adult EP fellowships were recruited. We performed a cohort study comparing the traditional teaching methods with the VR learning environment. Participants completed a demographic questionnaire and a satisfaction survey. The adult EP trainees were given a multiple-choice pre- and post-test exam to assess their anatomical knowledge. Both the adult and pediatric EP trainee cohorts rated the VR experience positively and preferred the VR environment to the more traditional teaching method. All the participants expressed interest in incorporating the VR learning environment into the EP fellowship curriculum. The usability of the system was relatively low, with approximately one-third of participants rating the system as hard to use. The impact of the VR session on exam performance was mixed among the adult cohort. We demonstrated the feasibility of gathering geographically dispersed EP fellows in training with a shared VR-based environment to teach cardiac anatomy. Although we were not able to demonstrate a learning benefit over the traditional lecture format in the adult cohort, the training environment was favorably received by all the participants.

Overcoming High Impedance in the Transitional Area of the Distal Great Cardiac Vein during Radiofrequency Catheter Ablation of Ventricular Arrhythmia

(1) Background: Radiofrequency catheter ablation (RFCA) is an essential treatment for ventricular arrhythmia (VA). However, high impedance in the transitional area of the distal great cardiac vein (TAODGCV) often leads to ablation failure. This study aimed to explore the factors influencing impedance and identify effective ways to reduce impedance. (2) Methods: A total of 156 patients with VA arising from the TAODGCV received RFCA therapy at our center from October 2009 to August 2021 and were retrospectively analyzed. Local impedance variation during RFCA was monitored, recorded, and analyzed. (3) Results: The impedance increased from the proximal to distal portions of the TAODGCV and decreased by increasing the saline flow rate at the same site. To overcome high impedance, we implemented the following strategies: (1) Reset the upper limit impedance to 300 Ω and accelerate the saline flow rate to 60 mL/min (effective in 118 of 144 patients); (2) turn off the upper limit impedance (effective in eleven of 21 patients); (3) use high-flow-rate irrigation devices (effective in five of 15 patients); and (4) increase the upper limit temperature (effective in six of ten patients). (4) Conclusions: In the TAODGCV, local impedance is mainly influenced by the target site location and saline flow rate. We concluded several methods to overcome the high impedance and contribute to a successful ablation.

Morphometric Characterization of Human Coronary Veins and Subvenous Epicardial Adipose Tissue-Implications for Cardiac Resynchronization Therapy Leads

Subvenous epicardial fat tissue (SEAT), which acts as an electrical insulation, and the venous diameter (VD) both constitute histomorphological challenges for optimal application and lead design in cardiac synchronization therapy (CRT). In this study, we characterized the morphology of human coronary veins to improve the technical design of future CRT systems and to optimize the application of CRT leads. We retrospectively analyzed data from cardiac computed tomography (CT) of 53 patients and did studies of 14 human hearts using the postmortem freeze section technique and micro CT. Morphometric parameters (tributary distances, offspring angles, luminal VD, and SEAT thickness) were assessed. The left posterior ventricular vein (VVSP) had a mean proximal VD of 4.0 ± 1.4 mm, the left marginal vein (VMS) of 3.2 ± 1.5 mm and the anterior interventricular vein (VIA) of 3.9 ± 1.3 mm. More distally (5 cm), VDs decreased to 2.4 ± 0.6 mm, 2.3 ± 0.7 mm, and 2.4 ± 0.6 mm, respectively. In their proximal portions (15 mm), veins possessed mean SEAT thicknesses of 3.2 ± 2.4 (VVSP), 3.4 ± 2.4 mm (VMS), and 4.2 ± 2.8 mm (VIA), respectively. More distally (20-70 mm), mean SEAT thicknesses decreased to alternating low levels of 1.3 ± 1.1 mm (VVSP), 1.7 ± 1.1 mm (VMS), and 4.3 ± 2.6 mm (VIA), respectively. In contrast to the VD, SEAT thicknesses alternated along the further distal vein course and did not display a continuous decrease. Besides the CRT responsiveness of different areas of the LV myocardium, SEAT is a relevant electrophysiological factor in CRT, potentially interfering with sensing and pacing. A sufficient VD is crucial for successful CRT lead placement. Measurements revealed a trend toward greater SEAT thickness for the VIA compared to VVSP and VMS, suggesting a superior signal-to-noise-ratio in VVSP and VMS.