Ischemic conditioning (delay phenomenon) improves esophagogastric anastomotic wound healing in the rat

Abstract

BACKGROUND AND OBJECTIVES: Esophagogastric anastomotic leaks are a major source of morbidity after esophagectomy. Occult ischemia of the mobilized gastric fundus is an important etiological factor for this failure of healing. To test the hypothesis that ischemic conditioning (delay phenomenon) could improve esophagogastric anastomotic healing, anastomotic healing was studied in a rodent model of partial gastric devascularization. METHODS: Thirty-four Sprague-Dawley rats (two groups of 17 rats) underwent partial gastric devascularization and creation of esophagogastric anastomoses. In the acute ischemia group, devascularization and anastomosis were done at the same laparotomy. In the ischemic conditioned group, devascularization was done 3 weeks before anastomosis. Gastric tissue perfusion was assessed by laser-Doppler flowmetry before and after devascularization in both groups, and 3 weeks after devascularization in the ischemic conditioned group. All rats were killed 4 days after anastomosis, and the wounds assessed for dehiscence, breaking strength, and hydroxyproline concentration. RESULTS: Gastric tissue perfusion, measured in tissue perfusion units (TPU) decreased immediately after devascularization (before: 73.6 +/- 12.1 TPU; after: 25.0 +/- 6.5 TPU; P < 0.001). After 3 weeks, gastric tissue perfusion returned to baseline values in the ischemic conditioned rats (before: 72.3 +/- 11.0 TPU; 3 weeks, 71.1 +/- 15.1 TPU; P < 0.80). Ischemic conditioned rats had fewer anastomotic leaks (2 vs. 9, P < 0.023) and higher anastomotic wound breaking strengths (2.35 +/- 1.05 N vs. 1.56 +/- .76 N, P < 0.02) than the acute ischemic rats. Anastomotic would hydroxy-proline concentration was not significantly different in the two groups (acute ischemic--0.111 +/- .033 mumol/mg, ischemic conditions--0.097 +/- .026 mumol/mg, P < 0.20). CONCLUSIONS: In this rodent model of partial gastric devascularization, ischemic conditioning (delay phenomenon) ameliorated the harmful effect of ischemic on esophagogastric anastomotic wound healing.