The Effect Of Expansion Prefabrication On Crossing Area Supply Axial Pattern Flap

【Objects】(1) To establish an experimental model for axial pattern flap with acrossing area supply and to provide a macroscopic anatomic evidence for relative flapresearch. (2) To explore the effects of tissue expansion on the anastomoses and thesurvival of the axial pattern flap with a crossing area supply. Further purpose of theresearch is to improve the survival of crossing area axial pattern flap and to provide anew idea for the development of original crossing area axial flap. (3) The theory ofbridging effect of expansion prefabrication in crossing area axial pattern flap is to beconfirmed and generalized clinically【methods】(1) The integument arteries of minipig torso were observed and analyzedthrough gross anatomy, angiography and 3D reconstruction to search for an ideal axialflap model with a crossing area supply. An square axial flap measured 20cm×20cmthat included superior epigastric vessels was elevated based on the deep iliaccircumflex vessels. Anatomic territories of deep iliac circumflex artery was observedangiographically. (2) The identical square flaps as above were designed bilaterally onown control and divided into expansion group and control group(experiment A),expansion group and delay group(experiment B). Angiographic analysis, histologicalexamination, blood perfusion examination and gross survival observation were carriedon. (3) 4 cases of cervico-mandibular adhesion caused by scars were underwenttransferring operation of crossing area axial flap based on the branch of transversecervical artery after expansion prefabrication.【results】(1) The cephalo-dorsum skin and superficial fascia of minipig torso isdominantly supplied by small segmental perforators, including posterior perforators ofintercostal arteries and thoracodorsal artery perforators, whereas at the ventri-caudalpart, bigger direct skin arteries and perforators are the dominant supplies. Theyinclude perforators of superior epigastric artery, lateral perforators of intercostalarteries and deep lilac circumflex artery. The anatomic territory of deep iliac circumflex artery bordering on superior epigastric artery is about 20cm×7～10cm,1/3～1/2 of designed flap. (2) Angiography showed that in expansion group, deepiliac circumflex artery and superior epigastric artery are fully perfused with abundantanastomoses and big calibers, that in delay group, the two arterial systems werevisualized but with relatively less anastomoses, smaller calibers and smaller territory,and that in control group, the superior epigastric artery is hardly visualized. (3) Theblood perfusion of distal and proximal part of all flaps descend firstly and then ascend.There were no significant differences among proximal part of all flaps. In experimentA, the blood perfusion of distal part of the flap in expansion group was significantlysuperior to the control group 48 hours postoperatively. In experiment B, the bloodperfusion of distal part of the flap in expansion group was similar to the delay group.(4) The results of histological comparison showed a hypervascularity phenomenonin the expanded part of the flap, but at the corresponded part of delay and controlgroup, there were far less vessels at the subdermic layer, in the distal part, congestionoccurred more frequently in the control and delay group than in the expansion group.(5) The survival rate in expansion group is significantly higher than the controlgroup in experiment A. The survival rate in expansion group is significantly higherthan the delay group in experiment B. (6) All the narrow pedicled, thin flaps with acrossing area supply survived thoroughly and no ischemia and congestion wereobserved.【conclusions】(1) A 3-D structure model of minipig integument vessels canprovide a direct evidence for the design and development of flaps. A flap that includedsuperior epigastric vessel based on the deep iliac circumflex vessel is an idealexperimental model for the crossing area supply axial pattern flap. (2) The mechanismof improvement of flap survival is bridging effect:①Expansion prefabrication canchange choke anastomoses into real anastomoses, make the crossing area supplyeasier, bridge two neighboring axial vessels and improve the flap survival;②expansion procedure is also a delay procedure;③expansion can lead to aneovascularity result and a dilation of the vessel caliber, so the perfusion of the skin is improved;④Expansion can ameliorate venous drainage. The probable mechanism isrelated to the valve imcompetence and the opening of communicating vein bypassingthe vavles. (3) The research of bridging effects of expansion on the axial pattern flapwith a crossing area supply and the probable mechanism can provide a guidance forthe clinical application and development of the axial pattern flap with a crossing areasupply. (4) The positive effect of expansion prefabrication on the crossing area axialflap is confirmed and it can be applied clinically.