The influence of perivascular tissue on lateral thermal expansion during bipolar vessel sealing

Lateral heat propagation has been an unavoidable effect of bipolar sealing with the risk of damage to surrounding structures. It is presently unknown whether leaving the perivascular tissue in situ may be advantageous in the sense of an isolation effect.

Two groups were formed from ex vivo carotid specimens. Group A (n = 10) consisted of carotid artery with the perivascular connective tissue in place (mean preparation diameter: 10.57 ± 0.16 mm) and group B (n = 10) of skeletonized carotids (mean vessel diameter: 5.21 ± 0.12 mm). All specimens were fixed on a plastic plate and mounted vertically in a holder. Sealing was performed perpendicular to the axis of the specimens. The temperature during the sealing process was recorded by a thermal camera. Group comparison was performed by a nonparametric test and significance was set at p < 0.05.

Mean sealing time in group A was 3.71 ± 0.37 s compared to 3.42 ± 0.37 s (p = 0.009) in group B. The maximum temperature in the middle of the jaws was significantly different. Group A had a temperature of 71.4 ± 3.9 °C and group B had a temperature of 91.4 ± 7.4 °C (p < 0.0001). RILATE risk scores (percent of necrotic zone in relation to potential area of necrosis) at both upper and lower sides of instrumental jaws were significantly different. For group A, it was 14.9 ± 1.6 at the upper side of jaws, 20.4 ± 2.63 at the lower side of jaws and for group B, it was 21.9 ± 3.5 at the upper side of jaws, 30.2 ± 6.2 at the lower side of jaws.

Perivascular connective tissue acts as an insulator with respect to lateral heat propagation. Peak temperature between instrument jaws is significantly reduced with perivascular tissue in situ. This may result in a negative impact on sealing quality.