Effect of sequence,timing of vascular anastomosis,and clamp removal on survival of microsurgical flaps

The effects of the timing and order of clamp removal in microsurgical transplants were studied in rat groin skin flap and rat latissimus dorsi muscle flap models. Forty rats were divided into four groups. In Group 1, the arterial pedicle of the skin flap was anastomosed first, and the clamp was released after the anastomosis was completed. The venous pedicle was then repaired after inflow was restored. In Group 2, the venous pedicle of the skin flap was anastomosed first. The venous clamp was not released until completion of the arterial anastomosis. In Group 3, the arterial pedicle was anastomosed first in the muscle flap. The venous anastomosis was then performed after the arterial clamp was released. In Group 4, the venous pedicle was anastomosed first, and both clamps were released simultaneously. The blood perfusion of the skin flaps was examined after both clamps were released in Groups 1 and 2. The flap survival status was examined 5 days postoperatively for skin flaps and at 3 days for muscle flaps. Skin flaps in an additional six rats were harvested for histology. The results showed that the flap blood flow for Group 1 was statistically significantly higher than for Group 2 flaps in the first 20 min after reperfusion. There was no significant difference of flow between these two groups during the 30 to 90 min after reperfusion. The difference in survival rates for the four groups was not significant. Histology revealed extensive congestion in the flaps from Group 1 after completion anastomoses, but the congestion was significantly decreased at 3 hr following reperfusion. In conclusion, a brief venous stasis during anastomosis, after establishment of arterial inflow, is not detrimental to flap survival. The sequence of anastomosis will not affect outcome for either the cutaneous flap or the muscle flap models. Early flap perfusion was increased when the arterial anastomosis was performed first.     

Muscle flap mass preservation with end-to-side neurorrhaphy: an experimental study

The authors examined the preservation of rat gracilis muscle flap mass after motor and sensory end-to-side neurorrhaphy. The rat gracilis muscle flap model was designed based on a previous study. Twenty-four Sprague-Dawley rats were divided into three groups. In Group 1 (n = 8), the flap was denervated by transecting the obturator nerve. In Group 2 (n = 8), the flap was reinnervated by coapting the proximal saphenous nerve to the distal obturator nerve. In Group 3 (n = 8), the flap was reinnervated by coapting the motor branch of the femoral nerve to the distal stump of the obturator nerve. At 6 months postoperatively, the gracilis muscle flaps were examined, harvested, and weighed individually. Results showed that the flaps with motor nerve reinnervation retained good bulk, with a weight of 634.0 +/- 65.1 gm, which was statistically significantly higher than the denervated group (457.5 +/- 125.3 gm, p < 0.01). However, muscle mass preservation in the sensory reinnervated group (606.9 +/- 209.1 gm) was not significantly different, compared to the denervated group. Histology revealed atrophic changes in the denervated group, compared to the sensory and motor-reinnervated groups. The authors concluded that muscle mass can be preserved by end-to-side nerve repair. Motor nerve reinnervation is able to better arrest atrophic changes of the muscle flaps.     

The deleterious effect of arteriovenous flow reversal during experimental free muscle transfer

Arteriovenous flow reversal (AVR) has been used experimentally to salvage ischemic limbs and to create novel skin flaps with some success. The clinical applicability of AVR in muscle by way of two arteriovenous anastomoses in the rabbit was investigated. Twenty-four rabbits were divided into two groups. In Group 1 (control), the rectus femoris muscle was harvested and transplanted in the opposite thigh, anastomosing the donor femoral artery to the recipient femoral artery, and the donor rectus femoris vein to the recipient femoral vein. In Group 2 (flow reversal), the same procedure was done except the donor artery was anastomosed to the recipient vein and vice versa. Six and 24 hr postoperatively, specimens were compared macroscopically and by weight and histology. Reversed flow muscles were significantly heavier than control muscles at 6 hr and at 24 hr. Histologically, 6 hr of AVR caused edema, intramuscular hemorrhage, neutrophil infiltration, and thrombosis of most vessels. By 24 hr muscle cell degeneration was well advanced. All control muscles were viable, with only mild edema and slight peripheral necrosis. Possible reasons for the failure of AVR in muscle are discussed. On the basis of these results, AVR in free muscle transfer is not advocated.     

Innervation of skin grafts over free muscle flaps.

Skin grafts regain their sensory innervation from the graft bed by the regeneration of nerve endings. Although some clinical studies report sensory recovery in skin grafts implanted on free muscle flaps, the mechanism of recovery is obscure. The purpose of this study was to investigate nerve regeneration in experimental skin grafts on free muscle flaps to elucidate this phenomenon. Thirty-eight male Sprague-Dawley rats, weighing 450-550 g were used in the study. The rat gracilis muscle flap was the free flap model transferred from one groin to the other using microvascular anastomoses. Full-thickness skin grafts harvested from the abdomen were used to cover the free muscle flaps after transfer. Four study groups were formed: Group I (n = 10): Free muscle flaps were transferred without any nerve anastomosis; Group II (n = 10): Free flaps transferred with the anastomosis of the muscle's motor nerve to a sensory nerve at the recipient site; Group III (n = 10): Free flaps transferred with the anastomosis of the muscle's motor nerve to a motor nerve at the recipient site; Group IV (n = 8): Skin grafts were placed directly on the fascia layer over the medial hindlimb muscles and served as controls. The specimens were harvested for histologic examination after 12 weeks. Histologic examination was performed to visualise regenerating nerve endings using H&E, S100, Luxol Fast Blue and tyrosine hydroxylase staining. The specimens were categorically scored according to the staining pattern of neural structures around pilosebaceous units and statistical comparisons were performed by using paired t-test. Skin grafts in both Group II and Group III markedly received tyrosine hydroxylase at the base of their pilosebaceous units in many of the specimens and functional nerve twigs could also be traced from the muscle layer to the overlying skin graft. In contrast, the skin grafts in Group I did not show any nerve function in the central parts. The overall staining scores of Groups II, III and IV were significantly higher than Group I (P < 0.05; P < 0.001; P < 0.05, respectively). There was no statistically significant difference between other groups. No myelinated nerve fibres could be detected in any of the skin grafts with Luxol Fast Blue technique. It was concluded in the present study that skin grafts over reinnervated free muscle flaps can develop significantly better innervation than skin grafts over non-innervated muscle flaps. However, the activity in skin appendages indicating nerve regeneration may only imply a gross sensation and in the absence of any myelinated nerve fibres transmission of finer sensation cannot be expected in any of the study groups.     

Microvascular transfer of anterior and posterior gracilis muscles in rats

A microvascular free muscle flap in rats using the anterior and posterior gracilis muscles with femoral vessels as its pedicle is presented. The gracilis muscles form a single unit supplied by the muscular branch artery and vein, averaging 0.3 mm and 0.4 mm in diameter, respectively. These small sizes preclude their use in transplantation. However, the muscular branch vessels in continuity with the femoral vessels can be used for the vascular pedicle in this muscle transplant. This muscle flap was transplanted to the contralateral femoral vessels by end-to-end anastomosis in 15 rats. Thirteen animals survived and 11 flaps were viable at 3 days for a success rate of 85%. The gracilis flaps averaged 674 mg in weight, 1.87 cm X 1.36 cm in size, and 7.23 mm in pedicle length. This free muscle flap model is reliable, relatively easy to perform, and provides adequate muscle bulk for pharmacologic and biochemical studies in transplanted muscle. No lower extremity complications were noted following femoral vessel ligations.     

Effects of methylprednisolone on the viability of experimental flow-through venous flaps

In this study, the effects of a corticosteroid, methylprednisolone, on the survival of flow-through venous flaps were investigated in rabbits. Flow-through venous flaps, sized 3.0 x 4.5 cm, were raised in the rabbit-ear model. Animals were randomly distributed into three groups, and 30 flaps were raised as follows: Group 1 (n=10): control flow-through venous flaps (intramuscular saline injection 2 ml/d); Group 2 (n=10): flow-through venous flaps with daily intramuscular methylprednisolone injection (30 mg/kg/d); and Group 3 (n=10): negative control composite grafts with the flow-through vein ligated at both edges of the flap. All injections were done 24 hr and 1 hr preoperatively, and for 5 days postoperatively. Observations included gross and histologic examination, and percentage of survival of the flaps on the tenth day. Venous flaps of the animals receiving daily methylprednisolone injections (Group 2) were noted to have statistically significantly improved flap survival ( p<0.05), compared to the control group (Group 1). Flaps in Groups 1 and 2 demonstrated significantly higher survival rates, compared to the composite grafts ( p<0.01). Histologic examination of methylprednisolone-treated animals showed normal stratified squamous epithelium, while complete necrosis was noted in the composite grafts. Untreated flow-through venous flaps demonstrated patchy epidermal sloughing, crusting, and partial necrosis. These results suggest that the survival of potentially ischemic flow-through venous flaps can be enhanced in rabbits by daily methylprednisolone treatment in the perioperative period. Increased tolerance to ischemia and modulation of venous flap microcirculation might be possible mechanisms for this salutary effect.     

Reconstruction of soft tissue after complicated calcaneal fractures.

A total of 35 flap reconstructions were done to cover exposed calcaneal bones in 31 patients. All patients had calcaneal fractures, 19 of which were primarily open. Soft tissue reconstruction for the closed fractures was indicated by a postoperative wound complication. A microvascular flap was used for reconstruction in 21 operations (gracilis, n = 11; anterolateral thigh, n = 5; rectus abdominis, n = 3; and latissimus dorsi, n = 2). A suralis neurocutaneous flap was used in eight, local muscle flaps in three, and local skin flaps in three cases. The mean follow-up time was 14 months (range 3 months-4 years). One suralis flap failed and was replaced by a latissimus dorsi flap. Necrosis of the edges that required revision affected three flaps. Deep infection developed in two patients and delayed wound healing in another four. During the follow-up the soft tissues healed in all patients and there were no signs of calcaneal osteitis. Flaps were considered too bulky in five patients. Soft tissues heal most rapidly with microvascular flaps. In the long term, gracilis muscle covered with free skin grafts gives a good contour to the foot. The suralis flap is reliable and gives a good final aesthetic outcome. Local muscles can be transposed for reconstruction in small defects.     

The gracilis myocutaneous free flap in swine: An advantageous preclinical model for vascularized composite allograft transplantation research

Vascularized composite allotransplantation (VCA) has become a clinical reality, prompting research aimed at improving the risk‐benefit ratio of such transplants. Here, we report our experience with a gracilis myocutaneous free flap in Massachusetts General Hospital miniature swine as a preclinical VCA model. Fourteen animals underwent free transfer of a gracilis myocutaneous flap comprised of the gracilis muscle and overlying skin, each tissue supplied by independent branches of the femoral vessels. End‐to‐end anastomoses were performed to the common carotid artery and internal jugular vein, or to the femoral vessels of the recipients. Thirteen of fourteen flaps were successful. A single flap was lost due to compromise of venous outflow. This model allows transplantation of a substantial volume of skin, subcutaneous tissue, and muscle. The anatomy is reliable and easily identified and harvest incurs minimal donor morbidity. We find this gracilis myocutaneous flap an excellent pre‐clinical model for the study of vascularized composite allotransplantation. © 2012 Wiley Periodicals, Inc. Microsurgery 2013.     

Reconstruction of recurrent pressure sores using free flaps.

The authors describe two successful reconstructions of recurrent pressure sores with free fasciocutaneous flaps. In Case 1, a free lateral thigh flap pedicled on the first and third direct cutaneous branches of the deep femoral vessels was used to cover a large recurrent sacral pressure sore. The vascular pedicle was dissected to the deep femoral trunk proximally and anastomosed to the inferior gluteal vessels. In Case 2, a free medial plantar flap was transferred to a recurrent ischial pressure sore. The vascular pedicle was dissected to the posterior tibial vessels proximally. The long vascular pedicle of the flap was passed through the femoral subcutaneous tunnel, and end-to-side microvascular anastomoses were performed to the superficial femoral trunk without any vein grafts. The authors advocate the use of free tissue transfer for recurrent pressure sore reconstruction.     

Evaluation of Role of Arterialization of Venous Flaps in Abdomen in Rats

Introduction  Reconstruction forms the primary tenet in plastic surgery. Venous flaps are a known option but the survival is limited. Arterialization of venous flap can enhance its survival. While various techniques of arterialization of venous flaps are described, there are very few studies comparing them. Material and methods  The current study was conducted among 34 rats weighing 160 to 200 grams. The rats were divided into four groups. Group I—islanded epigastric flap was raised with superficial caudal epigastric vessels as pedicle. Group II—arterialized flow through venous flap was raised with superficial caudal epigastric vein (SCEV) as afferent and lateral thoracic vein as drainage vein. Side-to-side anastomosis was done between femoral artery and vein, lateral to the origin of superficial caudal epigastric artery. Group III—after raising the flap, as in group II, femoral vein was ligated proximal to superficial caudal epigastric vessels. Group IV—an arterialized flow through venous flap was raised with superficial caudal epigastric vein as afferent and lateral thoracic vein as drainage vein. End-to-side anastomosis was done between femoral artery and superficial caudal epigastric vein. Animals that died before completion of the study were excluded. The color changes of flaps were noted. Flap survival was expressed as a percentage of the total flap surface area. The patency of anastomosis was seen on postoperative day 5. Results  There was no total flap failure. On statical analysis, the flap survival area on day 5 between Group I and Group IV was not significant ( p value 0.431). The survival area in Group I (78.85 ± 10.54%) was comparable to Group IV (65.71 ± 20.70%). Group II and III had poor results as compared with Group I. In four rats, thrombosis of arteriovenous anastomosis was noted with flap survival area of 30 to 33%. Conclusion  It was noted that epigastric venous flaps with end-to-side anastomosis between femoral artery and superficial caudal epigastric vein (group IV) have survival area comparable to islanded flaps.     

An experimental study of the flow-through venous flap: investigation of the width and area of survival with one flow-through vein preserved.

A quantitative analysis was undertaken to investigate the width and area of survival of flow-through venous flaps in 20 ears of 10 rabbits. The 3.0- x 3.0-cm flap models, which included one flow-through vein, were prepared with additional circulation from the graft bed and surrounding tissue excluded, as far as possible. The flaps were divided as follows: Group A--composite grafts (n = 10), and Group B--flow-through venous flaps (n = 10). All flaps in Group A became necrotic and all those in Group B showed partial survival along the flow-through vein. The average survival width was 1.10 +/- 0.48 cm, and the survival rate was 44 +/- 19.3 percent. Microangiograms revealed patency of the flow-through vein in all flaps of Group B. Histologically, there tended to be progressively more fibrous tissue in the area further away from the flow-through vein. The model is useful to investigate the width and area of survival in flow-through venous flaps.     

Optimizing the use of local muscle flaps for knee megaprosthesis coverage

Primary muscle flap cover of megaprostheses following limb salvage surgery for tumors around the knee serves to decrease infection rates, provide additional soft tissue cover over the implant, and act as a bed for split-skin grafting. The purpose of this study is to demonstrate the role of supplementary muscle flaps such as the hemisoleus, gracilis, and semimembranosus in augmenting coverage provided by gastrocnemius muscle flaps. Between August 1999 and August 2006, 10 patients underwent resection of distal femur (n = 5) or proximal tibia (n = 5) sarcomas, followed by bone reconstruction with a modular megaprosthesis and soft tissue coverage with local pedicled flaps. The average age was 31 years (range, 13 to 47), with pathologic diagnoses inclusive of osteosarcoma (n = 7), chondrosarcoma (n = 2), and recurrent giant cell tumor (n = 1). For proximal tibial tumors, both bellies of the gastrocnemius with hemisoleus for additional soft tissue cover were used. For distal femoral tumors, 1 gastrocnemius belly sutured to the extensor mechanism and gracilis or semimembranosus provided adequate soft tissue cover. All flaps survived without complications, all wounds healed well, and all patients were ambulant after surgery. The role of supplementary muscle flaps was demonstrated in specific situations, where coverage of the subcutaneous area of the midtibia was deficient and where a significant amount of the vastus medialis or gastrocnemius has been resected. Technical refinements included primary skin grafting to relieve tension during skin closure and excision of the aponeurosis over the gastrocnemius and hemisoleus to increase the reach and surface area of the muscle flap.     

Effects of VEGF administration following ischemia on survival of the gracilis muscle flap in the rat.

The incidence of free flap transplantation failure is only 3% to 5%, yet still occurs in cases in which the flap suffers prolonged ischemia. The purpose of the current study was to determine the effects of vascular endothelial growth factor (VEGF)--a potent angiogenic agent with a suspected role in the protection of endothelium--on flap survival in a model of ischemia-reperfusion injury. The model chosen was the rat gracilis muscle flap. A total of 36 adult male Sprague-Dawley rats were divided into three groups (N = 12). One experimental group received VEGF treatment and the other received heparin. A third group was treated with saline and served as the control. The gracilis muscle flap was dissected and isolated based on a vascular pedicle originating at the femoral vessels. Following 3.75 hours of ischemia, induced by clamping the femoral vessels, either VEGF, heparin, or saline was infused directly into the pedicle of the flap via a cannula. The flaps were evaluated both grossly and histologically after 72 hours of reperfusion. Eleven of the 12 flaps from the VEGF group survived, whereas the survival rate was 6 of 12 and 5 of 12 flaps for the heparin- and saline-treated groups respectively. Flap survival was significantly greater in the VEGF-treated group compared with the heparin- and saline-treated groups (p < 0.025, p < 0.01 respectively). Furthermore, there was no significant difference between the heparin and saline groups. These results indicate that VEGF plays a role in reducing the damage that occurs in ischemia-reperfusion injury, and that the use of VEGF holds promise as a potential therapy for increasing flap survival.     

Quadriceps femoris muscle flap: largest muscle flap model in the rat.

The purpose of this paper is to present a new muscle flap in the rat: the quadriceps femoris muscle flap based on a pedicle consisting of the femoral vessels. In order to establish the anatomic details of this model, seven rats were explored bilaterally, and the regional anatomy of the thigh was examined. The technical aspect of the model was established by the unilateral harvesting of 18 quadriceps femoris muscles. Findings were that this muscle is primarily supplied by a muscular branch originating at the superficial circumflex iliac artery. The average muscle weight was 6 g and the average pedicle length with femoral vessels was 6 mm. Eight of the harvested flaps were transplanted to the contralateral thigh, and the pedicle was anastomosed to the femoral vessels. The other ten flaps were resutured back to their beds. At 72 hr postoperatively, all flaps were viable with the exception of one of the transplanted flaps which was found to be necrotic. The quadriceps femoris muscle flap is technically both a reliable and simple model. With an average weight of 6 g, this flap is by far the largest described in the rat, and offers a convenient model for testing flap-related techniques and outcomes.     

Vascular resistance in human muscle flaps

Important differences in free muscle flap survival have been reported in the setting of long arterial and venous vein grafts. The authors provide insight into the etiology of flap failure by addressing the following question: Do differences in flap type result in clinically significant different vascular resistances and consequently anastomotic patency? A total of 15 human flaps were studied intraoperatively: 9 gracilis, 3 rectus abdominis, and 3 latissimus dorsi. The muscle was isolated on a single pedicle and hemodynamic stability was ensured. The venous pedicle was then divided. A timed collection of effluent was used to determine flow. Vascular resistance was calculated by dividing the change in pressure by the flow, and standardizing this for temperature and hematocrit. Average vascular resistance and standard deviation for the gracilis, rectus, and latissimus flaps was 10.34 +/- 7.77 mmHg per milliliter per minute, 2.79 +/- 1.50 mmHg per milliliter per minute, and 3.17 +/- 1.05 mmHg per milliliter per minute respectively. An inverse relationship between muscle vascular resistance and flap mass was found (p < 0.001). This indicates that larger muscles have less vascular resistance. The decreased resistance gives rise to higher flow rates and, as a result, potentially improved vein graft patency. The clinical implication is that a larger flap should be used when high flow-through is critical. The role of flap vascular territory makeup continues to be pursued.     

Internal jugular vein versus external jugular vein anastamosis: implications for successful free tissue transfer

BACKGROUND: Microvascular free flaps are becoming the reconstructive option of choice for many head and neck defects. Many previous studies have examined factors predicting free flap survival. No study has compared differences in free flap survival when anastomosed to the internal or external jugular systems. METHODS: Retrospective review of all free flaps performed at an academic medical center by a single head and neck microvascular surgeon during the period July 1995 to December 1999. Flaps were closely monitored postoperatively and taken back to the operating room urgently for arterial insufficiency or venous congestion. RESULTS: On hundred fifty-six free flaps were performed during this time period. Sixty-five free flaps were anastomosed to the external jugular (EJ) vein and 86 to the IJ system (62 to the proximal common facial vein, 17 end-side on the IJ, and 7 to other branches). Five had either two venous anastomoses or were anastomosed to other veins and were excluded from statistical analysis. Six (4%) vascular thromboses occurred; 5 were venous and 1 arterial. Success by group was 99% for IJ anastomosis (1 arterial thrombosis) and 92% for EJ anastomosis (5 venous thromboses, p =.03). Urgent anastomotic revision and reperfusion salvaged 5 of the 6 flaps (overall success 99%). CONCLUSIONS: Although the overall success rate (96% success with 99% success with salvage) is comparable to other large series, microvascular free flaps anastomosed to the external jugular vein failed at a significantly higher rate than those anastomosed to the IJ system. This suggests that the IJ system should be used as a recipient vessel when feasible.     

Free-flap coverage technique with double vascular bypass in the lower limb]

In thirteen patients, the repair of a soft tissue defect of the lower limb required a free tissue transfer revascularized by microvascular grafts. The indication of vascular grafting was either the absence of vessels or inadequate recipient vessels. Proximal anastomoses were performed on the femoral artery and the femoral vein or the long saphenous vein. All the transfers were done in one stage procedure. In two cases, a transitory arteriovenous shunt was established. Three flaps out of thirteen have been lost by thrombosis. The discussion concerns the causes of the failures and the indication of the establishment of a transitory or a temporary arterioveinous shunt prior to free flap transfer.     

Clinical experience with non-penetrating vascular clips in free-flap reconstructions.

To date, the gold standard for performing a microvascular anastomosis has been the penetrating suture with attached needle. During the last two decades, non-penetrating techniques have been introduced, including the Unilink system for end-to-end anastomoses, and the VCS clip-applier system for both end-to-end and end-to-side anastomoses. The aim of this study was to compare the results of different techniques used to create microvascular anastomoses in free-flap reconstructions. Between January 1995 and October 1999, we performed 474 microvascular anastomoses in 216 consecutive free-tissue transfers. The anastomosis techniques included manual sutures (42%), Unilink rings (34%) and VCS clips (24%). Seven combined sutured-clipped anastomoses were excluded from further analysis. The mean anastomotic time when rings were applied was significantly shorter than when using clips (P 0.0001) or sutures (P 0.0001). Venous anastomoses using clips took less time than those using sutures (P 0.05). There were 19 anastomotic failures, all of which lead to early flap failure. Ten flaps were salvaged by early reoperation; nine flaps were lost. Three more flaps were lost as a result of other causes, bringing the flap survival rate down to 94.4%. Early flap failure was caused by failure of the arterial anastomosis in eight cases; all of them were sutured (these represented 5% of all arterial anastomoses with sutures). None of the clipped arterial anastomoses failed. Early flap failure was caused by failure of the venous anastomosis in 11 patients. Three of these anastomoses were sutured (representing 6% of all venous anastomoses with sutures), seven were anastomosed with rings (representing 5% of all venous anastomoses with rings) and one was clipped (representing 2% of all venous anastomoses with clips). Both the VCS clip-applier system and the Unilink system are easy to handle and allow fast microvascular anastomoses without intraluminal penetration. The patency rate of clipped vessels is at least as good as the patency rates of vessels anastomosed using sutures or rings.     

Different types of arteriovenous anastomoses between femoral artery and vein distal to the island groin flap

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.     

Effects of liposome-mediated gene transfer of VEGF in ischemic rat gracilis muscle

The purpose of the current study was to determine the effects of vascular endothelial growth factor (VEGF) on muscle flap survival and vascularity in a rat gracilis ischemia-reperfusion model. A total of 12 adult male Wistar rats were divided into two groups (n = 6). The experimental group received the plasmid encoding VEGF(165) cDNA plus lipofectamine (cationic liposome) injected directly to the gracilis muscle following 4 h of ischemia. The control group received lipofectamine only. The viability and vascularity of the flaps were evaluated after 7 days of reperfusion. The data demonstrated that the VEGF plasmid- and lipofectamine-treated muscle flaps had significantly greater total survival and capillary count 7 days after reperfusion compared with the flaps treated only with lipofectamine. These results indicate that VEGF exerts a protective effect on ischemic skeletal muscle flaps.