Abstract Background Advancements in multimodal treatments for chronic thromboembolic pulmonary hypertension (CTEPH) have significantly improved patient survival. Consequently, current therapeutic goals have shifted towards further symptom alleviation. Balloon pulmonary angioplasty (BPA) has rapidly gained global acceptance as an effective treatment option for inoperable CTEPH. Recent studies suggest that achieving complete revascularization, including occluded lesions, via BPA enhances hemodynamic outcomes and increases the attainment of WHO functional class I status. When collateral circulation is visible, it indicates the presence of occluded pulmonary arteries. However, when the proximal occlusion cannot be visualized or accessed, conventional antegrade BPA fails due to the inability to advance a guidewire into the lesion. As a result, these patients remain without effective treatment options. Transcollateral retrograde BPA emerges as a novel strategy for such lesions, though hardly any centers have sufficient experience. Purpose To evaluate factors influencing the success of transcollateral retrograde BPA. Methods A retrospective review was conducted on 593 BPA sessions performed on 122 consecutive patients at a Japanese expert center. Among these, cases in which transcollateral retrograde BPA was attempted were identified, excluding those via extra-pulmonary collateral routes (e.g., bronchial or internal thoracic arteries). The focus was on procedures via pulmonary artery-to-pulmonary artery collateral pathways. Results Out of 3,149 targeted lesions (segments) across 593 sessions, 29 lesions were approached via collateral routes. After excluding three lesions via extra-pulmonary collaterals, 26 BPA procedures were evaluated. The procedural success rate was 12 out of 26 (46%). Failure was predominantly attributed to two major challenges: (1) Guidewire passage through severely tortuous, narrow, or capillary-like collateral channels, and (2) Penetration of the hardened, elongated proximal occlusion. Conclusions Transcollateral retrograde BPA offers a viable option for lesions that cannot be treated by conventional antegrade BPA. Despite its potential, the current success rate remains suboptimal, highlighting the need for further refinement. Improving procedural success requires addressing challenges such as the pre-procedural selection of the optimal collateral pathway.Study flowchart Transcollateral retrograde BPA
Ikeda et al. (Sat,) studied this question.