Clinical experience of box lesions in pulmonary vein isolation in patients with a common inferior pulmonary vein

Objective A common pulmonary vein (CIPV) is a rare anatomical variant. Individualized strategy in pulmonary vein isolation (PVI) should be recommended in light of the anatomical feature of pulmonary veins (PV) . This study was to report about our experiences concerning Box lesion in achieving PVI in patients with confluent inferior pulmonary veins. To study the safety, feasibility and efficiency of the Box lesions. Methods Five patients with coalescence of inferior PV in Wuhan Asia Heart Hospital from Jan 2018 to Nov 2018 were enrolled in the study. All of the five patients who underwent PV isolation guiding by a 3D mapping system were diagnosed as presenting coalescent inferior PV. Ablation procedure was performed as described previously. The Box lesion was obtained by encircling all PV by an irrigating ablation catheter guided by a 3D mapping system. The radiofrequency ablation (RF) energy was delivered as power-coupled mode with the power limit of 25-35 W, 43℃ and flow-rate of 30 ml/min. Complete isolation of pulmonary veins was deemed as the endpoint of ablation. The general information of patients and data of measurement during radiofrequency ablation (RFCA) , including complications, immediate PVI effect, operation time, fluoroscopy time and radiation dose were collected. We followed up these patients at 1 month, 3 months and 6 months after RFCA to record all symptoms, Electrocardiogran (ECG) data and complications. Results There were 4 cases of paroxysmal atrial fibrillation and 1 case of persistent atrial fibrillation. The CHA2DS2-VASC score was 3.8±1.8, and the HAS-BLED score was 1.8±0.6. The left-right diameter of CIPV was (32.7±1.71) mm, and the upper-down diameter of CIPV was (25.7±4.50) mm Complete PVI was achieved in all of these five patients. Operation time was 82-188 (141.8±33.8) min, fluoroscopy time was 15-46 (25.8±13.1) min and radiation dose was 277-654 (439.6±144.7) mGy. No minor or major complications were observed peri-procedures. During 6-10 months of follow-up, no event of atrial fibrillation was detected. Conclusion Box lesion is a safe and effective treatment option in achieving complete PVI in patients with confluent inferior pulmonary veins. Key words: Atrial fibrillation; Common inferior pulmonary vein; Radiofrequency ablation