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.