Utilization of the delay phenomenon improves blood flow and reduces collagen deposition in esophagogastric anastomoses

Abstract

Objective: Complications of anastomotic healing are a common source of morbidity and mortality after esophagogastrostomy. The delay phenomenon is seen when a skin flap is partially devascularized in a staged procedure prior to its definitive placement, resulting in increased blood flow at the time of grafting. This effect may be applied to esophagogastrectomy, potentially reducing anastomotic complications.

Summary background data: The purpose of this investigation was to apply the delay principle to the gastrointestinal tract, investigate mechanisms by which it occurs and examine the effects of delay on anastomotic healing.

Methods: Thirty-seven opossums were assigned to Sham (n = 5), Immediate (n = 14), and Delay (n = 18) groups. Each underwent laparotomy and measurement of baseline gastric fundus blood flow. The Delay and Immediate animals underwent ligation of the left, right, and short gastric vessels and subsequent measurement of gastric fundus blood flow. The Delay group underwent repeat measurement of blood flow, esophagogastrectomy, gastric tubularization, and esophagogastrostomy 28 days after vessel ligation. The Immediate group completed the procedure immediately after vessel ligation. The anastomoses in both groups were harvested 32 days after esophagogastrostomy. The Sham group underwent blood flow measurement on initial laparotomy, followed by harvesting of esophagogastric junction 60 days later. Sections taken through the anastomoses were examined with trichrome-staining and immunohistochemistry (IHC) for actin. Collagen content of the gastric submucosa 5 mm below the anastomosis was quantified, and preservation of the muscularis propria and muscularis mucosa was determined histologically. Capillary content of the esophagogastric junction was quantified using IHC for vascular endothelium in the Delay and Sham groups.

Results: Blood flow decreased by 73% following vessel ligation in Delay and Immediate groups. The Delay group had over 3 times the gastric blood flow of the Immediate group at the time of anastomosis at 16 (interquartile range [IQR] 11-17) versus 5, (IQR 5-6) mL/min/100 g (P = 0.000003). Two Immediate animals developed anastomotic leak and died; the Delay group had no complications. Submucosal collagen content in Sham, Delay, and Immediate groups were 57% (IQR 52-62), 65% (IQR 57-72), and 71% (IQR 60-82), respectively (P = 0.0004). The median distance of full-thickness atrophy of the muscularis propria was 0.10 mm (IQR 0-0.60 mm) in the Delay group and 0.53 mm (IQR 0.03-0.80 mm) in the Immediate group (P = 0.346). Five percent of the Delay group had atrophy of the muscularis mucosa, whereas 19% of Immediate animals had atrophy of this layer (P = 0.023). Compared with the Sham group, all Delay animals developed dilation of the right gastroepiploic artery and vein. A median of 27 (IQR 23-33) capillaries per 20x field was observed in the Sham fundus and 38 (IQR 31-46) in the Delay fundus (P = 0.037).

Conclusions: The delay effect is associated with both vasodilation and angiogenesis and results in increased blood flow to the gastric fundus prior to esophagogastric anastomosis. Animals undergoing delayed operations have less anastomotic collagen deposition and ischemic injury than those undergoing immediate resection. Clinical application of the delay effect in patients undergoing esophagogastrectomy may lead to a decreased incidence of leak and stricture formation.

Figures

FIGURE 1. Timeline of interventions for the Delay, Immediate, and Sham groups.

FIGURE 10. Representative trichrome-stained section of the anastomosis in an Immediate animal. Broken line represents anastomosis between the esophagus (E) and the gastric tube (G). N denotes a needle hole. The inset depicts a higher magnification to show structures of interest: muscularis propria (MP), intact muscularis mucosa (black arrowheads), and areas of atrophy in the muscularis mucosa (white arrowheads).

FIGURE 2. Postligation visceral angiography in a Delay animal. Arrowheads identify the right gastroepiploic artery (RGE), the single remaining artery supplying the gastric pedicle after ligation of the left, right, and short gastric vessels.

FIGURE 3. Esophagogastrostomy. A hand-sewn anastomosis was performed at the distal end of the gastric pedicle. A marking suture was placed 5 mm distal to the tip of the gastric fundus (prior to resection) and remained in place throughout the entire study period. The pyloris indicates the distal end of the gastric tube.

FIGURE 4. Time courses of gastric fundus blood flow in the Delay and Immediate groups. Blood flow was measured by laser Doppler flowmetry. Solid line indicates median blood flow. Shaded boxes indicate interquartile range. Comparisons between baseline and postligation blood flow and between the postligation and next scheduled measurement of blood flow were statistically significant.

FIGURE 5. Median blood flow at time of esophagogastrostomy in the Delay and Immediate groups.

FIGURE 6. Anastomotic leakage at the esophagogastrostomy. This animal, which had been assigned to the Immediate group, developed sepsis and expired. The anastomosis was harvested, and the luminal side of the longitudinally opened specimen is displayed. The site of leakage is indicated between the esophageal (top) and gastric (bottom) conduit.

FIGURE 7. Collagen density in the submucosa of the gastric fundus. Using digital colorimetric quantification, measurements of collagen density were taken in 3 representative regions of interest 5 mm distal to the anastomosis. Overall measurements using every measured value in each group are given. When only the highest measurement in each animal was considered, the same trends persisted. A significant difference was noted between the Delay and Immediate groups, and a trend toward significance was noted between the Sham and Delay groups.

FIGURE 8. Right gastroepiploic (RGE) artery and vein, examined at baseline before ligation and after a delay period of 28 days. Qualitatively, the artery appears consistently more distended after the delay period compared with baseline. SG indicates short gastric vessels.

FIGURE 9. Capillary identification with immunohistochemistry for vascular endothelium. Representative transverse sections of gastric fundus from the Sham and Delay groups are shown. Arrowheads indicate structures identified as capillaries. In the Sham group, esophagogastric junctions were harvested 60 days after initial the laparotomy. In the Delay group, esophagogastric junctions were harvested after a 28-day period of delay.