Impact of Pulmonary Vein Cryoballoon Ablation on Bronchial Injury

Pulmonary Vein Cryoablation and Bronchial Injury IntroductionThere 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 degrees C, 3 minutes), prolonged (>-55 degrees C, 6 minutes), and conventional (>-55 degrees C, 3 minutes) Cryo-PV on lung/bronchial injury. Methods and ResultsFour 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 degrees C vs. -45 +/- 5 degrees C; P = 0.001), but did not differ between Cryo-B-Prolonged and Cryo-B-Conventional (-46 +/- 3 degrees C vs. -49 +/- 3 degrees 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. ConclusionCryo-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.