Experimental Investigation into Bipolar Sealability of Elastin-Rich Tissue

Elastin-rich vessels such as the aorta pose a particular challenge for bipolar tissue sealing due to their high elasticity and low compressibility. It is unclear under which conditions a mechanically resilient seal can be achieved in such tissues. The aim of this experimental study was to investigate the sealability of elastin-rich aortic wall strips from pigs. The influence of compression pressure and impedance control on the resulting peel forces is analyzed.

Porcine aortas were harvested immediately postmortem, segmented, and histologically characterized (hematoxylin-eosin (HE) and elastin-Van Gieson (EVG). Mechanical compressibility was determined uniaxially on full-wall disks (Ø 10 mm) and compared with carotid arteries Ø < 5 mm. Aortic strips (5 × 25 mm) were sealed bipolarly, first with a commercially available instrument. Further seals were performed employing a specially developed device that allowed defined compression pressures (2.5-10 kg) and variable final impedance settings (250 vs. 500 Ω). Sealing quality was quantified via peel force measurements. Statistical analysis was performed by Mann-Whitney U tests.

The aortic wall showed a high elastin content (42.8 ± 3.4%) and low compressibility (only 44.9% at 490 N), significantly lower than in carotid arteries (92.8% at 490 N). The standard instrument produced no stable seals at all. However, defined compression in the special setup led to significant improvements: mean peel force increased from 0.09 N (2.5 kg) to 0.71 N (10 kg; +68.8%). Increasing the interval between the initial and final impedance setting (500 Ω) further increased the peel force by 25.5% (0.32 ± 0.05 N) at 2.5 kg compression. Combining compression of 5 kg and 500 Ω final impedance interval achieved the highest stability (0.91 ± 0.2 N; p < 0.001). Histologically, vessel wall structures were not destroyed by the process; they remained largely intact. Coagulation zones were limited to the contact areas.

Resilient bipolar sealing of elastin-rich aortic wall tissue is fundamentally possible but requires defined mechanical compression and adapted impedance control. As this study relied exclusively on ex vivo peel-force measurements, the findings should be interpreted as mechanistic rather than clinically validated. Functional assessments, such as burst pressure testing and evaluation in intact vessel segments, will be required in future work.