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Background: Radiofrequency catheter ablation is the preferred treatment choice for ventricular arrhythmias (VAs) originating from right ventricular outflow tract (RVOT) in symptomatic patients and is usually performed under fluoroscopy guidance. Zerofluoroscopy (ZF) ablations using 3D mapping system applied for treatment of various types of arrhythmias are trending and practiced in many centers around the world, but rarely done in Vietnam. The objective of this study was to evaluate the efficacy and safety of zero-fluoroscopy ablation of RVOT VAs, compared with fluoroscopyguided ablation without a 3D electroanatomic mapping (EAM) system. Methods and Results:We conducted a nonrandomized, prospective single-center study including 114 patients with RVOT VAs that had electrocardiographic features of typical left bundle branch block, inferior axis QRS morphology, and a precordial transition ≥ V 3 , from May 2020 to July 2022. The patients were assigned (without randomization) to two different approaches of either zero-fluoroscopy ablation under the guidance of the Ensite system (ZF group) or fluoroscopy-guided ablation without a 3D EAM (fluoroscopy group) in a 1:1 ratio. After a follow-up time of 5.0 ± 4.9 months and 6.9 ± 9.3 months in the ZF and fluoroscopy groups, respectively, the results showed a higher success rate in the fluoroscopy group than in the complete ZF group (87.3% vs 86.8%), although the difference was not statistically significant. No major complication was noted in both the groups. Conclusion:ZF ablation for RVOT VAs can be done safely and effectively using the 3D electroanatomic mapping system. The results of ZF approach are comparable to that of the fluoroscopy-guided approach without a 3D EAM system.

In the continuing debate regarding the mechanism of atherosclerotic plaque formation in arteries, one question remains unanswered: While all arteries in a patient are exposed to the same systemic risk factors (hypertension, diabetes, aging, nicotine of cigarettes, etc.), why do plaques frequently present in the coronary arteries, and to a lesser extent in the arteries of the lower extremities, and still less in the carotid or renal arteries? Over the past five years, in order to find an answer to the above question, there has been a radical shift in our research strategy: The principles of fluid dynamics in industrial and domestic pipes/pipelines were employed to decipher changes in the cardiovascular system. The types of flow under investigation included laminar, entrance, turbulent, and helical flows in systole and diastole, as well as the interface between antegrade and retrograde flows resulting in water hammer shock and cavitation phenomena. We aim to highlight the similarities and differences among flow types in arteries and pipes and apply the same methodologies to study the formation, growth, and rupture of coronary plaques leading to inactive and active clinical syndromes and the beneficial mechanism of percutaneous coronary interventions (PCI). In this article, we list the questions and the answers based on the primary data of several completed studies and the preliminary results of ongoing projects from a fluid mechanics perspective. The angiographic coronary images of recirculation flow, vortex formation, collision, hammer water shock, and cavitation will be showcased in detail, and their videos in slow motion are uploaded in the addendum for further in-depth review.