Impact of Pulmonary Vein Cryoballoon Ablation on Bronchial Injury

Introduction: There is a paucity of data on the mechanisms of cough and hemoptysis that sometimes ensue from cryoballoon ablation of pulmonary veins (Cryo-PV). This study specifically examined the impact of ultra-cold (≤−60 °C, 3 minutes), prolonged (>−55 °C, 6 minutes), and conventional (>−55 °C, 3 minutes) Cryo-PV on lung/bronchial injury. Methods and Results: Four healthy adult swine underwent Cryo-PV. Each animal received Cryo-PV to the inferior common trunk and the right superior PV. In 2 animals, 1 PV was treated with 2 ultra-cold (Cryo-A_Ultra-cold) and the other with 2 conventional (Cryo-A_Conventional) cryoapplications. In the other 2 animals, 1 PV was ablated using 2 prolonged (Cryo-B_Prolonged) and the other with 2 conventional (Cryo-B_Conventional) applications. The nadir cryoballoon temperatures were lower in Cryo-A_Ultra-cold versus Cryo-A_Conventional (−66 ± 6 °C vs. −45 ± 5 °C; P = 0.001), but did not differ between Cryo-B_Prolonged and Cryo-B_Conventional (−46 ± 3 °C vs. −49 ± 3 °C; P = 0.123). Post-ablation bronchoscopy revealed immediate mucosal edema and erythema with/without bleeding in the adjacent bronchi in 100% of Cryo-A_Ultra-cold and 50% of Cryo-A_Conventional/Cryo-B_Conventional and Cryo-B_Prolonged. At 4 hours post-ablation, there were marked increases in bronchoalveolar macrophages (P <0.001), lymphocytes (P = 0.035) and neutrophils (P = 0.001). Furthermore, Cryo-A_Ultra-cold yielded the largest increase in the macrophage (P = 0.005) and neutrophil (P = 0.034) cell counts. While similar trends were seen in Cryo-B_Prolonged, these did not reach statistical significance. Conclusion: Cryo-PV can elicit acute bronchial inflammation, bleeding, and mucosal injury. While this was further augmented by ultra-cold cryoapplications, it was also evident to a lesser degree with prolonged and even conventional cryoapplications. The mechanism for this appears to be direct collateral injury.