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.

Perforator Detection by Thermographic Imaging Augmented With Tourniquet-Reperfusion: A Modified Approach and Preliminary Report in Distal Lower Leg Reconstruction.

BACKGROUND: Dynamic infrared thermography provides a new imaging method of perforator detection. This study introduces an augmented technique to improve its accuracy by tourniquet-reperfusion and reports its preliminary use in the distal lower leg reconstruction. METHODS: A tourniquet (450 mm Hg) was applied for 3 minutes on proximal thighs. After the tourniquet release, the rewarming rate and pattern of hotspots were observed by thermography to delineate the location and quality of perforators. The results were compared with those detected by computed tomographic angiography. Clinically, the local transferred posterior tibial artery or peroneal artery propeller perforator flap was performed in 9 patients for the distal lower leg reconstruction. RESULTS: There was a 20- to 140-second "perforator observing window" after the tourniquet release. Tourniquet-reperfusion augmented thermal imaging method (TRATIM) had a sensitivity of 90.3% and a positive predictive value of 93.3%. The TRATIM and computed tomographic angiography had an excellent concordance with a kappa index value of 0.839 (P < 0.001). Based on the TRATIM, 9 propeller perforator flaps were successfully designed and raised for the distal lower leg resurfacing. All flaps survived entirely, except one with size of 1.0 cm × 2.0 cm that had terminal necrosis. CONCLUSIONS: The TRATIM is a quick, easy, cheap, and reliable approach for perforator detection in the lower leg. With the aid of TRATIM, a customized propeller perforator flap could be raised efficiently for the distal lower leg reconstruction.

Comparison of arterial supercharging and venous superdrainage on improvement of survival of the extended perforator flap in rats.

BACKGROUND: Arterial supercharging and venous superdrainage have been the commonly used vascular augmentation techniques for resolving partial loss of flaps in reconstructive surgery. It remains controversial which one of them is more effective in improving flap survival. The purpose of this study was to compare the effect of distal venous superdrainage and arterial supercharging on the survival of an extended dorsal perforator flap in rats. MATERIALS AND METHODS: Sixty Sprague-Dawley rats were randomly divided into three groups (n = 20 in each group). An extended dorsal perforator flap with the size of 3 × 12 cm based on the deep circumflex iliac artery and vein was elevated in each rat. In arterial supercharging group, the thoracodorsal artery was retained as the distal supercharging vessel; In venous superdrainage group, the thoracodorsal vein was retained as the distal superdrainage vessel. In control group, no other arteries and veins were retained except the main vascular pedicle. On the seventh day after operation, the survival area of flap was calculated as a percentage of viable area to the total flap. Vascular changes in the choke zones were assessed by angiography. Microvascular density and diameter were assessed via immunohistochemistry staining of CD31 on the fifth day after operation. RESULTS: The flap survival area in arterial supercharging group was significantly higher than that in venous superdrainage group (98.9 ± 0.8% vs. 81.5 ± 3.5%, p < .001). By gross observation, the extent of dilation of choke zone vessels in venous superdrainage group was smaller compared with that in arterial supercharging group. The density of CD31-positive vessels and the diameter of choke zone vessels in arterial supercharging group were significantly larger than that in venous superdrainage group (23.4 ± 4.6 mm-2 vs. 13.1 ± 4.2 mm-2 , p < .05; and 37.5 ± 5.8 µm vs. 27.8 ± 4.9 µm, p < .05). CONCLUSION: Compared with venous superdrainage, distal arterial supercharging in the potential territory resulted in better survival of an extended dorsal perforator flap in a rat model.