Lateral Thoracic Artery Perforator Island Flap in Rat: Definition of Choke Vessels By Angiography and Immunohistochemistry

Perforator flaps have been used for last decade. However, experimental perforator flap models are limited. We described the experimental extended lateral thoracic artery perforator flap and standardized size of flap size.

The rats were randomly assigned to one of three groups: Group 1: vertical lateral thoracic artery perforator flap, group 2: horizontal lateral thoracic artery perforator flap, group 3: extended lateral thoracic artery perforator flap. Flap was raised on cranial perforator from dorsal branch of lateral thoracic artery (figure 1). On Day 7, the entire flaps along with the margins of necrosis were traced onto transparent sheets and full-thickness 1 cm skin samples from perforator zone, contralateral side and distal side were taken from flap for histopathological and immunohistochemical analysis. In group 1, 95.8% (±4.8) of  flap area were survived and , necrosis were seen in the 4.2% (±4.8) of total flap area . In group 2, 89.1% (±7.8) of  flap area were survived and , necrosis were seen in the 11.3% (±8.0)  of total flap area . In group 3, 92.3% (±5.0) of  flap area were survived and , necrosis were seen in the 7.7% (±5.0 of total flap area.

CD 11b, ICAM-1 and VEGFR-2 markers which has increased expression in 'choke zones' were analyzed. Immunologic markes were increased in perforator side, and controlateral side in group 1, the highest increase is observed in 'choke zone', and in perforator side compared to contralateral side in group 2 and 3(figure 2). In group 2 and 3  immunohistological findings are in compatible with harmony angiographic and the topographic findings. The increase in the 'choke zone' was statistically significant. The changes in choke vessel which are known to be quite important for flap viability is observed less condense in the contralateral back side

Lateral thoracic artery perforator flap  can be easily dissect and harvest from dorsal skin with a consistent percentage of necrosis.

Table 1. Flap total areas on the op Day and on Day 7 (mm² )

	Flap Total Area On the op. day	Flap Total Area On the Day 7	P
Group 1	4260,25±447,98	3665,5±273,05	0,003
Group 2	5177,63±742,34	4524,75±644,65	0,120
Group 3	7213±557,45	6526,38±466,66	0,028

Figure 1. Drawnings of flaps

Figure 2. Angiografic and immunohistologic analysis of groups.