| Part one Animal experimental study of venous superdrainage and arterial pressurization on the survival of distal transregional flap(triangiosome).Objective In clinic,venous superdrainage or arterial pressurization is usually used to improve the blood supply of the distal end of the transregional flap,but the mechanism is not clear.In this study,the effect and mechanism of venous superdrainage and arterial pressurization on the survival of distal transregional flap was studied by the animal model of transregional flap.Methods A total of 60 SD female rats aged 6-8 weeks were randomly divided into three groups:experimental group 1(venous superdrainage group),experimental group 2(arterial pressurization group)and control group(n=20).On the basis of the preparation of the rat model of left unilateral triangiosome transregional multiterritory perforator flap(including three vascular areas of thoracodorsal perforator,posterior intercostal perforator and iliolumbar perforator),three types of transregional flaps pedicled with iliolumbar perforator were constructed.Venous superdrainage group:pedicled with the iliolumbar perforator,separated and ligated the posterior intercostal perforator and thoracodorsal artery to retain its accompanying vein.Arterial pressurization group,pedicled with the iliolumbar perforator,separated and ligated the thoracodorsal perforator and posterior intercostal vein to retain its accompanying artery.Control group:pedicled with iliolumbar perforator,separated and ligated the thoracodorsal and posterior intercostal perforators.All flaps were sutured in situ after operation and all rats were raised in single cage separately.7 days after operation,the survival area of flap in each group was marked.The Canon digital camera was used to take pictures on the same plane of the flap,then the image information was input into image J 6.0 software to calculate the gray value.Transcutaneous blood flow and oxygen pressure were measured by laser Doppler at 0 hour,6 hours,1 day,2 days,3 days and 7 days after operation.Lead oxide-gelatine mixture injection angiography was performed in all rats under abdominal anesthesia at the 7th day after operation,After 1 day of freezing treatment,the flaps were cut and paved again,then all flaps were photographed with full digital X-ray imaging system(FCR XG-1,Fujifilm).The vascular enlargement and patency in the area of perforator and choke vessels were observed.Results At the 7th day after operation,almost all the flaps in the experimental groups survived successfully.The necrosis area of transregional flap in the two experimental groups was significantly lower than that in the control group and the survival area in the venous superdrainage group was significantly higher than that in the arterial pressurization group.From 6 hours after operation,the transcutaneous blood flow and oxygen pressure in the experimental groups were significantly higher than those in the control group,and the transcutaneous blood flow and oxygen pressure in the venous superdrainage group was the highest among the three groups.At the 7th day after operation,Lead oxide-gelatine mixture injection angiography showed iliolumbar arteries and veins in each group had obvious diameter expansion.perforator in all groups.The microvascular anastomosis in the "choke vessels" in the venous superdrainage group was more abundant than that in the arterial pressurization group.In the control group,no obvious microvascular anastomosis was found at the distal end of the flap due to insufficient blood perfusion.Conclusion Both venous superdrainage and arterial pressurization can improve the blood perfusion of the distal end of the transregional flap,and the effect of venous superdrainage is more obvious.However,the mechanism of improving the survival rate of the distal end of the flap is different.Through changing the blood outflow channel,venous superdrainage increases the pressure difference between arterial perfusion of vascular pedicle and venous superdrainage.By gradually expanding the choke vessels,it reduces the arterial perfusion resistance to the distal end of flap,so as to improve the blood supply at the distal end of transregional flap and improve its survival area.Arterial pressurization can improve the blood supply of the distal end of flap by increasing the local arterial perfusion.However,the problem of blood reflux of the distal end of flap has not been effectively solved.The hemodynamic mechanism of two ways to change the distal microcirculation of transregional flap needs to be further explored.Part two The animal experimental study on the effect of venous anastomosis position on venous superdrainage and arterial anastomosis position on arterial pressurization in transregional flap.Objective Based on the conclusion of the first part,both venous superdrainage and arterial pressurization can improve the blood perfusion of the distal end of the transregional flap.In this experiment,the effects of venous anastomosis position on venous superdrainage and arterial anastomosis position on arterial pressurization were further studied on the animal model of transregional flap to find the factors and mechanism resulting in necrosis of the distal flap.Methods The model of transregional flap on the left back of SD female rats aged 68 weeks including mutiple angiosomes was established.Each flap consisted of three angiosomes:iliolumbar perforator,intercostal posterior perforator and thoracodorsal perforator.The choke vessels were between the two angiosomes.(1)The effect of venous anastomosis location on venous superdrainage:60 SD female rats were randomly divided into three groups:control group(n=20),experimental group 1(intercostal posterior vein group,n=20)and experimental group 2(thoracodorsal vein group,n=20).In control group,only iliolumbar perforator was preserved.In the intercostal posterior vein group,iliolumbar perforator and posterior intercostal vein were preserved,and other arteries and veins were ligated.In the thoracodorsal vein group,iliolumbar perforator and thoracodorsal vein were preserved,and other arteries and veins were ligated.(2)The effect of arterial anastomosis position on arterial pressurization:60 SD female rats were randomly divided into three groups:control group(n=20),experimental group 1(intercostal posterior artery group,n=20)and experimental group 2(thoracodorsal artery group,n=20).In control group,only iliolumbar perforator was preserved.In the intercostal posterior artery group,iliolumbar perforator and posterior intercostal artery were preserved,and other arteries and veins were ligated.In the thoracodorsal artery group,iliolumbar perforator and thoracodorsal artery were preserved,and other arteries and veins were ligated.At the 7th day after operation,the survival of the transregional flap was observed and the necrotic area of the flap was marked,then the canon digital camera was used to take pictures on the same plane of the flap and analyze it with software.Under the 40x eyepiece of stereomicroscope(Leica-DFC320,Leica company),the microvascular enlargement of"choke vessels 1" and "choke vessels 2" in each group during operation and 7 days after operation was observed and photographed,After unifying the field size and pixels,the pictures were imported into scion image beta 4.02 software to measure the relative diameter of blood vessels(expressed in pixels)and calculate the enlargement ratio of choke vessels 1.At the 7th day after operation,blood samples were collected from the tail vein of rats in each group,and then the serum was separated by centrifugation and the content of lactic acid in rats was detected by automatic biochemical analyzer.Results The main results were as follows:(1)7 days after operation,flaps in the two experimental groups survived well,and the survival area of both groups was significantly higher than that in the control group,in which the thoracodorsal vein group was better than the intercostal posterior vein group.Compared with the immediate results of operation,choke vessels in each group were enlarged 7 days after operation under the 40x eyepiece of stereomicroscope.Compared with the control group,the microvascular enlargement of choke vessels 1 in the experimental groups was obvious,and the microvascular enlargement of thoracodorsal vein group was the most obvious.At the 7th day after operation,the lactic acid value of the experimental groups was significantly lower than that of the control group,and the lactic acid value of the thoracodorsal vein group was the lowest.(2)At the 7th day after operation,the flap in the thoracodorsal artery group survived well.However,there was partial necrosis in the intercostal posterior artery group and control group,but the distal flap survival rate in the intercostal posterior artery group was still better than that in control group.Compared with the control group,the microvascular enlargement of choke vessels 1 in the experimental groups was obvious,and the microvascular enlargement of the thoracodorsal artery group was the most obvious.At the 7th day after operation,the lactic acid value of the experimental groups was significantly lower than that of the control group,and the lactic acid value of the thoracodorsal artery group was the lowest.Conclusion The main results are as follows:(1)The farther the venous anastomosis is from the vascular pedicle,the more obvious the effect of venous superdrainage is,and the higher the survival rate of the distal transregional flap is.The farther the vein anastomosis position of venous superdrainage is from the vascular pedicle,the greater the pressure difference between arterial perfusion of the vascular pedicle and venous superdrainage.After all choke vessels in the transregional flap are gradually enlarged,the normal arterio-venous reflux can be formed to ensure the survival of the distal end of the flap.(2)The farther the arterial anastomosis is from the vascular pedicle,the more obvious the effect of arterial pressurization is,and the higher the survival rate of the distal transregional flap is.As the vascular pedicle artery perfusion needs to cross two choke vessels,the local arterial perfusion can be directly promoted through arterial anastomosis at the distal end of the flap.Its effect of arterial pressurization is obvious and it’s beneficial to the distal survival of the transregional flap.Part Three Clinical study on distal survival of transregional flap in the lower leg for skin defect of foot and ankle by venous superdrainage or arterial pressurizationObjective Based on the experimental conclusions on the survival of the distal end of transregional flap by venous superdrainage and arterial pressurization.In clinic,the skin defect of foot and ankle was repaired by transregional flap through venous superdrainage with distal venous anastomosis or arterial pressurization with distal arterial anastomosis.Compared with the traditional surgical treatment,the clinical application value of venous superdrainage and arterial pressurization in the design of transregional flap was analyzed.Methods From May 2016 to July 2019,29 patients with skin defect of foot and ankle were randomly divided into group A and B.15 patients in group A were treated with transregional flap by venous superdrainage or arterial pressurization,while 14 patients in group B were treated with traditional distally pedicled transregional flap without anastomosis of distal deep or superficial vein and perforating artery.The necrosis,color,texture,sensation and function of the distal flap were observed in the two groups.The patients were followed up for six months.The data of the two groups were statistically analyzed by SPSS 20.0.Results There was no significant difference in preoperative baseline data between the two groups(P>0.05).In group A,there was minimal necrosis at the distal end of 1 Sural neurocutaneous flap pedicled with peroneal perforator in group A.Arterial pressurization was performed without ligating the small saphenous vein at the distal end of the flap.It was considered that the venous pressure at the distal end of the flap was too high,which limited the vein reflux.The wound healed after regular dressing change finally.Partial necrosis at the the distal end of the flap occurred in 2 cases and complete necrosis occurred in 1 case in group B.There were 2 cases of perforator pedicled propeller flap distally pedicled with peroneal artery,1 case of perforator pedicled propeller flap distally pedicled with posterior tibial artery.Two cases of distal partial necrosis healed by regular debridement and dressing change 3 weeks later.One case of distal complete necrosis healed after two surgical debridement and autologous medium thickness skin grafting.There was significant difference on the follow-up effect between the two groups(P<0.05).Conclusion When the transregional flap is designed to repair the wound defect of foot and ankle,the venous superdrainage of distal venous anastomosis and the arterial pressurization designed by distal arterial anastomosis or central designed vascular pedicle of the flap can obviously improve the distal blood supply of the transregional flap and prevent the distal necrosis of the flap.In principle,the distance between the perforator pedicle and the distal end of the transregional flap should not exceed two choke vessesls.The retrograde superficial vein(such as great and small saphenous veins,etc)is usually not recommended during operation. |
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