The differences in histological changes among pulmonary vessels divided with an energy device.

OBJECTIVES: Histological changes after division of the pulmonary artery (PA) and the pulmonary vein (PV) using a vessel-sealing device are not fully understood. The goal of the present study was to clarify histologically and immunohistochemically how division with the device affects the wall layers of the pulmonary vasculature.

METHODS: This prospective cohort study analysed outcomes of 20 patients who underwent anatomical lung resection. After a single proximal ligation, the PA and the PV (diameter 2-7 mm) were divided using a LigaSure Blunt Tip (LSB). Histological findings and thermal damage were evaluated in vascular specimens from resected lungs.

RESULTS: The PA has a well-developed media with rich elastic fibres and a thin adventitia, whereas the PV has a thinner media and a thicker adventitia with abundant collagen fibres. Vascular division of the PAs and PVs appeared complete to the naked eye. However, in all divided PAs, the area adjacent to the sealed zone comprised only adventitia and thin disrupted media. Additionally, thermal energy generated by the LSB resulted in a wide area of thermal necrosis over the histologically fragile region in all cases. Conversely, the wall layers of all divided PVs were completely fused without disruption. Thermal spread and disruption did not significantly differ between small (2-4 mm) and large (5-7 mm) PAs [187 (150-253) vs 236 (190-275) μm, P = 0.22; 180 (138-200) vs 210 (161-305) μm, P = 0.22]. Histological changes differed significantly between the pulmonary vessels after division using the LSB.

CONCLUSIONS: Surgeons should consider that dividing the pulmonary vessels with a vessel-sealing device might have more histological impact on the layers of the wall of the PA than on those of the PV, although it remains unclear whether these findings constitute a clinical risk.