Evaluation of a temporary arteriovenous shunt to establish neovascularization in a musculocutaneous flap: An experimental study

Vascular endothelial growth factor (VEGF) is a potent promoter of angiogenesis that has been shown to enhance revascularization of ischemic tissues, including skin flaps. This study was designed to investigate the value of a single topical application of recombinant human VEGF to accelerate flap viability in a rat model of a non-ischemic prefabricated flap. Prefabricated flaps were created in 48 Sprague-Dawley rats. An autologous tail artery loop was anastomosed to the femoral artery and vein, and implanted subcutaneously in the lower abdomen. Flaps were divided into two groups of 24 each. At the time of loop implantation the control group received 0.9 percent NaCl or a 16 percent vol/wet polyvinyl alcohol (PVA) solution: the treatment group received VEGF in 0.9 percent NaCl or VEGF in PVA. The PVA gel was used to facilitate topical application In each group, 3- x 4-cm flaps nurtured by the tail artery pedicle were elevated and resutured into place after 3, 4, and 5 weeks. The percentage of surviving skin of each flap was determined by planimetry 7 days after flap elevation. Mean skin survival areas at 3, 4, and 5 weeks were control group 0 percent. 8 percent and 17.5 percent; and VEGIF-treated group, 6 percent, 40 percent, and 66.7 percent respectively VEGF significantly improved flap survival by 5 weeks (p = 0.02). These results suggest that VEGF can accelerate maturation of prefabricated flaps. This approach could expand the application of flap prefabrication as a resource for reconstructive surgery.

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Accelerated Flap Prefabrication with Vascular Endothelial Growth Factor

Reis²,

Zhang³

et al. 2000

“…During the same period, several articles have appeared reporting the use of arteriovenous anastomoses as an adjunct procedure. [3][4][5][6][7][8][9][10] However, somewhat confusing usage of the terms involved has also been noted (see above).…”

Section: Discussionmentioning

confidence: 99%

Different Types of Arteriovenous Anastomoses between Femoral Artery and Vein Distal to the Island Groin Flap

Yenidünya¹,

Yenıdünya²,

Suse³

et al. 2002

An experimental study was done in rats in which the animals were randomly divided into four groups. Each group included bilateral standard island groin flaps. The right side flap was used as control. On the left side, after elevation of the flap, different types of arteriovenous connections were constructed distal to the pedicle between the femoral artery and vein. The connection type was a type-C (end-to-end) anastomosis in Group 1; a type-X (side-to-side) anastomosis in Group 2; a type-T a (artery-end-to-vein-side) anastomosis in Group 3; and a type-Tv (vein-end-to-artery-side) anastomosis in Group 4. Flow values in the flaps were measured externally and repeatedly using a laser Doppler flowmeter. Extremity changes, signs of congestive heart failure, flap weights (measured at the end of the study), thrombosis at the anastomosis or distal to it, edema in the flaps, subcutaneous venous stasis, and aneurysm formation in the anastomoses were observed. Histopathologic evaluations were also done. Only the side-to-side anastomosis group showed any aneurysm formation in the distal vein, as well as extremity changes and signs of congestive heart failure in some of the animals. Only the artery-end-to-vein-side group showed distal thromboembolism in some animals. All flaps survived, but there was prominent edema in the flaps of Group 2 and Group 4 animals in decreasing order. All the study flaps demonstrated subcutaneous venous stasis and capsule formation. The authors concluded that although any arteriovenous communication located distal to the pedicle of an island skin flap that connects the arterial to the venous system, bypassing microcirculation, may have some beneficial effects, it is not devoid of some possibly hazardous developments, including edema formation and venous stasis.

“…Several investigators have produced variations of these models of flap prefabrication in both laboratory and clinical settings. [1][2][3][4][5][6] Despite advances in our understanding of the prefabrication process, the clinical utility of flap prefab-rication is still limited by the amount of viable tissue that can be successfully transferred. Based on reports from prior investigations of arteriovenous (A-V) fistulas providing adequate neovascularization to support a free flap, 3,7 we have developed the tail artery interpositional loop (TAIL) flap model.…”

mentioning

confidence: 99%

Effect of VEGF on Tail Artery Interpositional LOOP (TAIL) Flap: A Rodent Model for Flap Prefabrication

Stebbins

Fan²,

Silver³

et al. 2005

The authors introduce an experimental model of flap prefabrication, the tail artery interpositional loop (TAIL) flap. In this model, an arterial segment from a rat tail is used to create an arteriovenous (A-V) fistula. This fistula is positioned beneath the abdominal skin flap to vascularize the overlying tissue, and a barrier of Silastic sheeting is placed below the fistula to prevent vascular ingrowth from the underlying bed. The efficacy of this new model was tested by investigating the effect of a single topical application of recombinant human VEGF (165). Treatment and control groups each contained 20 animals. In the control group, mean survival skin areas at 1, 2, 3, and 4 weeks were 12.5 percent, 27 percent, 35 percent, and 50 percent, respectively. In the VEGF (165)-treated group, survival rates were 14.8 percent, 37 percent, 48 percent, and 74.3 percent, respectively. Statistically significant differences were noted between the two groups at the 2-week ( p = 0.047), 3-week ( p = 0.048), and 4-week ( p = 0.023) time intervals. The authors conclude that the TAIL flap is a novel and useful animal model to study flap prefabrication.