gms | German Medical Science

Objectives/Interrogation: Experimental evidence suggests the positive effect of botulinum toxin A (BTX-A) on pedicled flaps' viability, but few focus on how to identify preoperatively the delay effect induced by BTX-A.

Methods: Fifty-two Sprague-Dawley rats were divided into the control and delay groups. A pedicled flap of 11×3 cm was marked on the rat unilateral dorsum. In the delay group, 15 IU of BTX-A was injected subcutaneously along the flap boundary and then the flaps were elevated at 2, 3 and 4 weeks after BTX-A injection, respectively. Before flap harvest, both the infrared (IR) thermal imaging and temperature of the flap donors were recorded, and both the number of the dilated choke vessels and microvessel density in the choke zones were evaluated by postmortem arteriography and CD31 staining. The survival area of the flaps was measured on postoperative day 7.

Results and Conclusions: After BTX-A injection, IR thermography of the flap donors showed that the independent white hotspots of the angiosomes enlarged and fused; both the temperature of the flap donors and number of the dilated choke vessels in the choke zones increased significantly within 3 weeks, but no significant difference was detected between the 4-week delay group and the control. The microvascular density manifested a continuously increased trend over time. No significant difference was detected in the survival area of the flaps among the delay groups, although it increased significantly when compared to the control.

Combined use of IR thermography and temperature of the flap donors can identify preoperatively the maximal delay effect of BTX-A.