An Experimental Study On Retrograde Hydraulic Destroyment Of The Great Saphenous Vein Valves Of Rabbit Saphenous Reverse-flow Island Flap

Background The reverse-flow island flap play a significant role in repairing surface defects. The direction of blood flow within the flap vascular pedicle is opposite to physiological condition both in the artery and veins. Because of the blocking effect of venous valves,venous congestion is prominent after the operation. The insufficient venous return further leads to flap necrosis.Purpose In order to explore the features of hemodynamics after operation and the final survial of the reversed island flap with interventionof the hydraulic destroyment of the great saphenous vein valves. And to provide a reference for clinical application.Methods The saphenous reverse-flow island fasciocutaneous flap was successfully established in New Zealand White rabbit.Each rabbit lower limbs were divided into experimental and control groups randomly.In the experiment group,about 5ml dilute heparin was pressurized into the great saphenous vein antidromicly after the formation of the reverse flow island flap.And it must be seen the transparent liquid flowed into the distal vascular.Vascular pedicle in control group was without special treatment.Twenty one rabbits were randomly assigned for different examination:6 rabbits for venous pressure measurement,6 rabbits for ultrasonic test,and 9 rabbits for calculation of flap survival ratio and H-E staining.Venous pressure measurement:venous pressure within the great saphenous vein was measured by the JPY-01H pressure transducer instrumentation,which was connected to RM6240 multi-channel physiological measurement machine.Prior to measurement, the pipeline was filled with diluted heparin,and the standard atmospheric pressure was set as the standard of 0 cmH20.At 5min, 10min,15min,20min,30min,45min and 60min after the operation the pressure was recorded.The differences of the measurement data were compared with the paired t test by using GraphPad 6.0 statistic software.Ultrasonic test:polyethylene film was palced under the flap,and then each flap was sutured in situ.Bloodstream in the veins were monitored by color doppler ultrasound for seven days after operation to observe the blood regurgitation.Caculation of flap survival ratio and H-E staining:in the experimental and the control group,each end of the saphenous vein within the vascular pedicle ends was ligated,only the great saphenous vein was retained as the venous outflow channel.The rest of the treatments were the same.Ten days after the operation, survival ratios were compared with the paired t test.H-E staining of the survival flaps was performed to observe the angiogenesis and the microthrombus within the flaps.Results Venous pressure measurement:① after the operation,the intravenous pressure of the experimental group decreased immediately, While the decline of the control group was observed 20min late.②the intravenous pressure values of experimental group at each time were significantly lower than that of control group(p<0.05).③the decline value of each flap within 1 hour was caculated, the value of experimental group was 8.40±1.67 cmH2O,and of the control group was 4.62±2.10 cmH2O. There is no statistical difference between two groups(P=0.19).Ultrasonic test: reverse flow through the venous valves was observed earlier in the experimental group.on the First day after operation in experimental group the retragrade flow of the great saphenous vein was recorded.The great saphenous vein retragrade flow of the control group was recorded 3 days after operation.Calculation of flap survival ratio and H-E staining:①postoperative gross view:on thelst,3rd,5th,7th day after surgery,more severe tissue swelling and congestion was observed in the control group.②the survival ratios of each flap were caculated on the 10th day after operation, the value of experimental group and control group was 45.76±12.64%,and 92.16±2.73%.There is a statistical difference between the two groups(P<0.01).③HE staining of flaps:microvessel density of the experimental group is higher than the control group.And there is without observation of microthrombus in the micrangiums of the experimental group.