229-01: Hepatic capsule enhancement during MR-guided ablation of atrial flutter: a mechanistic insight into procedural pain

Abstract

Introduction: Radiofrequency (RF) ablation for atrial flutter can be associated with chest and shoulder tip pain. However, the pain mechanism is not well understood, and may be related to pericardial irritation, somatic nerve stimulation or hepatic ablation. Live MR-guided ablation of atrial flutter enables real-time assessment of collateral injury and provides a unique insight into the phenomenon. Methods: An MR-guided RF ablation system (Imricor Medical Systems and Philips Research) was used to treat atrial flutter within an MRI scanner under general anaesthesia. 9 patients underwent a point-by-point ablation, mean ablation time 18.1 (±7.2) min (35–45 W, irrigated). Real-time imaging was performed during ablation, with immediate imaging post-procedure (<30 min, T2-weighted and LGE) and late LGE scar imaging at 3 months. Results: All patients had evidence of mild T2W enhancement at the diaphragmatic surface of the left lobe of the liver. 7 (78%) had acute enhancement of the hepatic capsule on LGE. There was significant anatomical variability of the left hepatic vein in terms of calibre (median 4mm, range 1.4–9mm) and proximity to cavotricuspid isthmus (6mm, range 3–18 mm). The presence of a large vein in close proximity to the CTI was associated with a reduction in acute hepatic capsule enhancement, with no enhancement detected within 4mm of the vein. Hepatic capsule enhancement persisted at 3months, but there was no late scar within liver parenchyma.