Identification of Unequal Flow-Carrying Capabilities of Choke Vessels in Rat Abdominal Flaps

Background Although the angiosome concept is a well-accepted theory, unexpected necrosis suggests that other factors can influence the flap survival. Our study uses the rat model to explore the flow capacity of the choke vessels across 2 angiosomes. Methods The medioventral line of Sprague-Dawley rats' abdominal flap was equally divided into 4 sections, which were preserved in 7 different groups (n = 6/group): A, no dissection; B to D, preserve the inferior 1/4, 2/4, and 3/4 sections; E to G, preserve the superior 1/4, 2/4, and 3/4 sections. The ratio (%) of the survival area of the distal/proximal territory was calculated. Indocyanine green, lead-oxide gel imaging, hematoxylin and eosin, and CD31 histology tests were performed. Results Compared with 96.0 +/- 1.4% flap survival in group A, groups B, C, and D had distal territory flap loss (34.8% +/- 4.1%, 65.0% +/- 3.7%, and 94.3% +/- 3.1% respectively). Group E lost the majority of the distal territory (3.5% +/- 2.4%), whereas groups F and G (15.5% +/- 3.8% and 79.2% +/- 3.3%, respectively) had larger flap survival. Except for groups A and D, each of the other 2 groups showed statistically significant results (P < 0.001). Indocyanine green indicated no blood flow at the superior 1/4 part. Lead-oxide gel and histology showed that the choke vessels residing along the medioventral line had no significant difference. Conclusions Choke vessels do not carry blood flow equally. Two categories of choke vessels-"resting" and "active"-are proposed. The "active" form has variable flow carrying capabilities when the flap is harvested in different designs.