Prolonged indwelling time of temporary vascular shunts is associated with increased endothelial injury in the porcine mesenteric artery.

BACKGROUND

Temporary intravascular shunts (TIVS) have been used as a damage control surgery (DCS) adjuncts in superior mesenteric artery (SMA) injuries, both experimentally and clinically. However, no study to date has evaluated the relationship between shunt indwelling time and resultant endothelial cell (EC) injury. We hypothesized that prolonged use of TIVS in SMA injuries would jeopardize EC integrity.

METHOD

After laparotomy, the SMA was clamped and transected while pigs were hemorrhaged to 40 mm Hg for 30 minutes. A TIVS was inserted between transected ends of the SMA without systemic anticoagulation. Totally, 24 animals were resuscitated and randomized to different shunt indwelling time groups: A, 3 hours; B, 6 hours; C, 9 hours; and D, 12 hours. Patency of shunts was monitored and recorded. Continuous wave Doppler was used as a determinant of adequacy of flow through the shunts. Transmural SMA biopsies from areas of TIVS placement were examined with electron microscopy for histopathologic injury after staining with hematoxylin and eosin and immunofluorescence using a validated histopathologic injury score (minimum-maximum score: 0-4).

RESULTS

Severity of endothelial injury was observed to be directly related to shunt indwell time. SMA transmural biopsies harvested from group D animals showed the most profound injury, demonstrating extensive EC denudations and marked intimal rupture (injury grade, 3.4 ± 0.2). Sections from group A animals revealed the mildest EC injury (1.3 ± 0.3 vs. group D p < 0.01). No significant difference was detected between group A and B. EC injury grade in group C (2.7 ± 0.6) was higher than that in group B (1.8 ± 0.6) but did not reach statistical significance (p = 0.58).

CONCLUSION

When possible, vascular reconstruction following use of shunts should include an interposition graft after debridement of the arterial edges having interfaced with the shunt. Finally, to minimize intimal injury to the native vessel, this model suggests that indwell times of shunts should be <9 hours.