Occlusion assessment tools
A stepwise protocol was employed to evaluate the performance of the baseline and injection tools for the assessment of PV occlusion. (Figure 1) In occlusion assessment step 1, the baseline tool was employed and resulted in 3 outcomes: 1) 3 points: the occlusion wheel showed all green; 2) 2 points: the occlusion wheel showed 1/4 red; 3) 1 point: the occlusion wheel showed > 1/4 red. If> 2 points were acquired in the baseline tool, then come to the next step, otherwise the CB should be adjusted to achieve a better contact and reassessed with the baseline tool until> 2 points were obtained.
Occlusion assessment step 2 (the injection tool) and step 3 (pulmonary venography) were performed simultaneously, with 4ml of contrast medium injected through the central lumen of CB. The injection tool resulted in 2 outcomes: 1) 1 point: the last quarter of the injection curve remained in the upper half; 2) 0 point: the last quarter of the injection curve fell into the lower half. Pulmonary venography resulted in 4 outcomes as previously reported11, 13: 1) grade IV: complete occlusion; 2) grade III: minimal leak; 3) grade II: moderate leak; 4) grade I: severe leak. If > grade III was achieved, cryoapplicants could be delivered, otherwise the operator should seek to readjust the CB and perform these steps again, or employ the “pull-down” technique or segmental cryoablation.