Pre-arterialisation of an arterialised venous flap: clinical cases.

Many factors affecting the survival of arterialised venous flaps have been elucidated, both experimentally and clinically. The survival of large arterialised venous flaps has been reported, with varying results. Large arterialised venous flaps with preformed arteriovenous fistulae at the donor sites have been successfully performed in experimental animals. We report the results of repair of skin defects in the extremities with arterialised venous flaps in eight patients. The arteriovenous shunts were created at the donor sites at least 2 weeks before the flaps were harvested. The flap sizes ranged between 4 x 4cm and 9 x 10 cm. Flap survival was between 93% and 100% of the surface area, as shown by digitalised scanning. In addition to the known advantages of venous flaps, such as less bulk, preservation of the main arteries and ease of harvesting, pre-arterialisation makes designing the flap easier due to the noticeable superficial veins. Pre-arterialisation, when used in carefully selected cases, did not prolong the hospital course of the patients.     

Use of an arterialised venous skin flap in the replantation of an amputated thumb.

We report the replantation of an amputated thumb using a venous skin flap, harvested from the volar surface of the forearm, to make up the soft tissue defect, and to restore the vascular continuity to the thumb.     

Retrograde arterialized venous flap: an experimental study

An experimental model was established to study circulation in retrograde arterialized venous flaps (RAVF). Venous flaps measuring 7 x 4 cm with a matching venous system were harvested from both forearms of 10 fresh human cadavers. In each trial, both flaps were simultaneously perfused with heparinized human blood driven by a pulsatile circulation model. In each trial there was one flap with retrograde perfusion, and one flap with antegrade perfusion. Clinical assessment, measurement of outflow, and angiographic examination with digitally assisted assessment after 3 h of perfusion showed better results for retrograde perfusion in 8 of the 10 trials. This study indicates that blood circulation in the periphery of arterialized venous flaps can be enhanced by retrograde arterialization.     

Use of an arterialised venous skin flap in the replantation of an amputated thumb

We report the replantation of an amputated thumb using a venous skin flap, harvested from the volar surface of the forearm, to make up the soft tissue defect, and to restore the vascular continuity to the thumb.     

An arterialised venous flap using the long saphenous vein

Free arterialised venous flaps and an arterialised osteocutaneous venous flap, fed by an arterialised long saphenous vein, were used successfully in three cases. This flap has a larger skin territory than those previously reported and the incorporation of bone into such a flap has not been reported before.     

Microcirculation of a venous flap: an experimental study with microspheres in rabbits.

In recent years, it has been found that maintenance of venous circulation alone may support a small flap with no direct arterial inflow. The clinical application of a venous flap has potential in the field of microsurgery. The purpose of this study was to evaluate the haemodynamics within a pedicled venous flap in rabbits, compared with those of a composite graft. Pedicled venous flaps and composite grafts were raised from the abdominal walls of 30 adult New Zealand rabbits. Flap survival was measured and recorded and blood flow studies with microspheres were done for seven days. The viability of the pedicled venous flaps was much better than that of the composite grafts. At two weeks 24 of the venous flaps (80%) showed more than 75% surviving, but 29 (97%) of the composite grafts had less than 25% surviving. The results suggest that the blood flow through a patent vein maintained in a venous skin flap can provide enough nutrients for the flap to survive during the initial three days until neovascularisation. The venous flap receives more blood flow than a composite graft. We conclude that a venous flap depends on blood supply from the axial vein in addition to neovascularisation to maintain its survival.     

Role of perivenous areolar tissue in the viability of venous flaps: an experimental study on the inferior epigastric venous flap of the rat.

This study was performed to investigate how the perivenous areolar tissue affects survival of the rat inferior epigastric venous flap model designed by Yuen and Leung (1991). Five groups of flaps were studied; group A--flap based on an inferior epigastric vein and areolar tissue; group B--flap with a skeletonised vein; group C--control, nonvascularised flap; group D--flap based on perivascular areolar tissue alone; group E--flap with a skeletonised artery and vein. Each group included 40 flaps; 20 of them had a silicone sheet placed under the flap, the other 20 did not. All flaps of group E survived. The success rate of group A with and without a silicone sheet was 60% and 90% respectively. All flaps of the other groups (B, C, D) necrosed. Histological examination of the pedicle showed that many minute vascular channels (single-cell-layered capillaries) were present apart from the inferior epigastric vein. This result confirms the importance of the perivenous areolar tissue in perfusion of the skin island, at least, in the inferior epigastric venous flap in the rat.     

Resurfacing of skin defects of the hand using the arterialised venous flap

In 22 patients an arterialised venous flap, with arterial blood only flowing through the vein of the flap, was used to cover skin defects of the hand. There were 17 complete successes, four partial successes and one complete failure. The main indications for use of the arterialised venous flap are to cover extensive skin loss with exposed bone or tendon where conventional flaps cannot be applied and to reconstruct the digital arterial defect where both revascularisation and skin coverage are needed.     

静脉瘀血对静脉动脉化皮瓣微循环的影响

目的研究静脉瘀血对静脉动脉化皮瓣微循环的影响。方法３０只新西兰大白兔随机分为Ａ、Ｂ、Ｃ３组，Ａ组为动脉皮瓣，Ｂ组为静脉动脉化皮瓣，Ｃ组为静脉瘀血的静脉动脉化皮瓣，每组各１０只。术后３０分钟，１，２，３，４，５小时分别应用显微电视系统通过耳窗对各组皮瓣微循环进行动态观察，７天后记录皮瓣成活情况。结果静脉瘀血的静脉动脉化皮瓣微循环血流缓慢，微血栓逐渐增多，皮瓣成活率低。结论静脉瘀血可破坏静脉动脉化皮瓣静脉系统的代偿机制，影响皮瓣血液灌流，从而导致皮瓣成活率下降     

静脉瘀血对静脉动脉化皮瓣微循环的影响

目的研究静脉瘀血对静脉动脉化皮瓣微循环的影响。方法 30只新西兰大白兔随机分为 A、B、C 3组,A 组为动脉皮瓣,B 组为静脉动脉化皮瓣,C 组为静脉瘀血的静脉动脉化皮瓣,每组各10只。术后30分钟,1,2,3,4,5小时分别应用显微电视系统通过耳窗对各组皮瓣微循环进行动态观察,7天后记录皮瓣成活情况。结果静脉瘀血的静脉动脉化皮瓣微循环血流缓慢,微血栓逐渐增多,皮瓣成活率低。结论静脉瘀血可破坏静脉动脉化皮瓣静脉系统的代偿机制,影响皮瓣血液灌流,从而导致皮瓣成活率下降。     

Free transplantation of venous network pattern skin flap: an experimental study in rabbits

Free skin flaps using rabbit ear to replace rabbit scalp have been accomplished using only arteriovenous and venous-venous anastomosis, without arterio-arterial anastomosis. The technique produced excellent graft survival in 30 of 33 rabbits. Without the vascular anastomosis control grafts did poorly. The mechanism of flow reversed revascularization is discussed.     

Thigh adductor flap: an experimental model for free flap transfer in the rat.

A new model of rat muscle free flap transfer is presented. The flap is based on a long pedicle originating from the femoral vessels and continuing down to the distal saphenous margin at the ankle. The distal portion of the semitendinosus muscle is harvested along with the saphenous artery and great saphenous vein. A larger muscle flap may be harvested by including the distal portions of the posterior and anterior gracilis muscles. The flap can be transferred to remote sites on the animal, with a vascular pedicle of up to 3 cm in length. The diameters of the vessels repaired are of standard microsurgical size. This model has distinct advantages of simplicity, speed of dissection, high success rate after microvascular transfer, and versatility in placement of the muscle mass (due to the long pedicle).     

The importance of venous drainage in rat flaps: an experimental study

Venous drainage of musculocutaneous grafts prepared on the backs of rats survived successfully by preserving the draining vein. Even in musculocutaneous flaps, venous drainage at the distal part of the flap plays an important role in a successful take. An experiment was prepared in a rat model in which the iliolumbar veins were utilized as the draining veins, and musculocutaneous flaps, 4 x 10 cm in size, were created. In this experiment, it was shown that even in random pattern musculocutaneous flaps, necrosis can be prevented by preserving the draining vein.     

The ideal rotation flap: an experimental study.

BACKGROUND/PURPOSE: Numerous modifications exist and opinions vary between surgeons with regard to the design of the ideal rotation flap. A literature review revealed inconsistencies as well as three different designs of rotation flap (standard rotation flap, Ahuja's modified rotation flap, divine rotation flap) based on entirely different concepts. It is not clear which of these designs serves its purpose best in wound reconstruction since they have not been previously examined experimentally and directly compared. The aim of this study is to determine the optimal rotation flap design in wound reconstruction. Several modifications of the standard rotation flap are examined and the three different rotation flap designs are directly compared. METHODS: This study tests the ability of various rotation flaps to close triangulated defects on sheets of neoprene, a synthetic rubber compound. Section A examines four important features in the design of the standard rotation flap: triangulation of a lesion, rotation flap circumference, pivot point and the back cut. Section B compares the standard rotation flap, Ahuja's modified rotation flap and the divine rotation flap. Tension resulting from wound closure is measured and the length of scar calculated. RESULTS/CONCLUSION: The standard rotation flap remains superior in comparison to the modified rotation flap and the divine rotation flap. Triangulation of a lesion should be performed with care and, in particular, the apex of the triangle should coincide with the geometrical pivot point. A flap circumference more than five times the width of the defect is of minimal benefit. The back cut is an effective modification and should be used if necessary.     

Transfer of a pedicled venous flap containing perivenous areolar tissue and nerve: an experimental study.

In this paper, we evaluated experimentally the feasibility of transferring a pedicled venous flap with perivenous areolar tissue into an ectopic site and investigated the role of each vein, the perivenous areolar tissue and nerve in the viability of pedicled venous flaps. Three groups of flaps were created using a rabbit-ear model: Group 1 (n = 11), containing perivenous areolar tissue and a draining vein; Group 2 (n = 10), perivenous areolar tissue, a draining vein and nerve; Group 3 (n = 10), only perivenous areolar tissue. Macroscopic, angiographic and histological assessments were performed 14 days after transfer. The total survival areas including superficial necrosis of Groups 1, 2 and 3 were 52.7%, 82.5% and 0%, respectively. There were significant differences in mean survival area and mean total survival area including superficial necrosis between Group 1 and Group 2 (P < 0.05). In contrast, all flaps in Group 3 became necrotic. These data suggest that a preserved vein is the necessary condition, and additional arterial flow through the preserved nerve and a small vascular network within the areolar tissue may play an important role in flap survival.     

An experimental study of the venous flap: investigation of the recipient vein

In previous studies using rabbit ears, total venous perfusion flaps (TVPF) were used that did not contain in the experimental model any chosen arteries truly representative of clinical venous flaps. We discovered that the TVPF could survive even under conditions of poor blood circulation. In the present study, conditions of the recipient veins were investigated using flow-through veins in TVPFs of rabbit ears and human dorsal digital veins. The research suggested that conditions for TVPF survival are a high density of the venous network in the flap and the presence of venous oscillation, high oxygen tension, and effective blood flow in the recipient vein.     

Comparison of venous drainage in reverse-flow island flaps: an experimental study of the rabbit saphenous fasciocutaneous flap

The mechanism of venous drainage in reverse-flow island flaps was investigated using the saphenous fasciocutaneous flap in New Zealand White rabbits. Ten animals were allocated into two groups of 10 flaps. In group I (left limb), the distal vascular pedicle (one saphenous artery and two venae comitantes) was not disturbed, maintaining the communicating and collateral branches intact. In group II (right limb), it was separated microsurgically from each other for 3 cm. Intravenous pressure was measured at 5, 15, 30, and 60 minutes after tourniquet release. The values of group II at 30 and 60 minutes were significantly lower (p<0.01) than those of group I. Ten days after flap elevation, the mean survival area of group I (95%) and group II (100%) was not significantly different. Histological examination of the vascular pedicle showed the saphenous veins in group II were more dilated than those of group I. These findings suggest that venous retrograde return in reverse-flow island flaps can be achieved more easily through a "direct incompetent valves route" than through a "circuitous communicating and collateral bypass route."