Epigastric Island Flap Research Articles

Propionyl-l-carnitine mitigates ischemia-reperfusion injury in rat epigastric island flaps

BackgroundIschemia-reperfusion injury presents a substantial concern in various medical scenarios, notably in reconstructive surgery involving tissue flaps. Despite reports on the protective benefits of Propionyl-l-carnitine against ischemia-reperfusion injury, a thorough assessment of its efficacy in epigastric island flap models is currently lacking. MethodsSixteen male Sprague-Dawley rats underwent epigastric island flap surgery and were divided into two groups: a Propionyl-l-carnitine group that received intraperitoneal Propionyl-l-carnitine prior to ischemia induction and a sham group that received saline treatment. A comprehensive evaluation was performed including macroscopic, biochemical and histological assessments encompassing measurements of flap survival areas, lipid peroxidation (malondialdehyde), glutathione, myeloperoxidase, nitric oxide and peripheral neutrophil counts. ResultsThe Propionyl-l-carnitine group demonstrated significantly increased flap survival areas when compared to the sham group. Administration of Propionyl-l-carnitine led to reduced malondialdehyde levels and elevated glutathione levels indicating a reduction in oxidative stress. Furthermore, the Propionyl-l-carnitine group exhibited lower myeloperoxidase levels, higher nitric oxide levels and reduced peripheral neutrophil counts, suggesting a decrease in the inflammatory response. Histopathological analysis revealed decreased levels of inflammation, necrosis, polymorphonuclear leukocyte infiltration and edema in the Propionyl-l-carnitine group. Additionally, vascularity was enhanced in the Propionyl-l-carnitine group. ConclusionThis study provides compelling evidence that Propionyl-l-carnitine administration effectively mitigates the deleterious effects of ischemia-reperfusion injury in epigastric island flaps. This is substantiated by the improved flap survival, diminished oxidative stress and inflammation, as well as the enhanced vascularity observed. Propionyl-l-carnitine emerges as a promising therapeutic intervention to enhance tissue flap survival in reconstructive surgery, warranting further exploration through larger-scale investigations.

The Effect of Ceruloplasmin Against Ischemia-Reperfusion Injury in Epigastric Island Flap in Rats

Flap surgery is frequently used in plastic surgery to close tissue defects. Ischemia-reperfusion (I/R) injury is a significant problem resulting in partial or total flap necrosis. This study aimed to investigate the effect of ceruloplasmin on I/R injury in epigastric island flaps in rats. A total of 32 male Sprague-Dawley rats were divided into four groups with eight rats in each group: The flap was not elevated in Group I; the flap was elevated without ischemia or any application in Group II, after the intraperitoneal saline and ceruloplasmin application the flaps were elevated and ischemia was created in group III-IV, respectively. Bilateral epigastric artery flap was elevated in all groups except Group I. After 6 h of ischemia, the flap was reperfused and inset. Samples were taken from the right and left side of the flap area in other groups at the postoperative 24th h for biochemical analysis (catalase and malondialdehyde-MDA) and the seventh postoperative day for histopathological analysis (Modified Verhofstad score and epidermal thicknesses), respectively. Image analysis for necrosis areas was performed on photos taken on the 7th d. Catalase level was significantly higher in Group IV.(0.15 ± 0.04 U/mg protein) (P < 0.05) Necrosis area percentage(14.4% ± 3.3%),MDA(3.6 ± 0.9 nmol/mg protein), edema(3), necrosis(2.75), and polymorphonuclear leukocyte infiltration(2.87) scores were significantly higher in group III.(P < 0.05). Fibroblast proliferation, collagen density (0.25), vascular density (0.25) scores and epidermal thickness (15.68 µm,) was significantly lower in group III. (P < 0.05) CONCLUSIONS: Our study demonstrated that ceruloplasmin application before ischemia reduced I/R injury in epigastric island flaps in rats.

Preventive effect of trimetazidine against ischemia-reperfusion injury in rat epigastric island flaps: an experimental study

For plastic surgery, ischemia-reperfusion (I-R) injury is a critical problem that results in partial or total flap necrosis. Trimetazidine (TMZ) is a drug used in the treatment of angina pectoris. This study investigated the effect of TMZ on I-R injury in epigastric island flaps using a rat model. Sixteen Sprague–Dawley rats were assigned to two groups, each with eight rats. The sham group comprised of saline-treated rats, while the TMZ group had TMZ-treated rats. An epigastric flap measuring 6 × 4 cm in size was created 30 min after the intraperitoneal administration of either physiological saline or TMZ in both groups. Ischemia was induced on the flaps for 10 h, followed by reperfusion. The flaps were then inset to the original position. Samples were obtained 24 h after reperfusion for biochemical analysis and on day 7 for histopathological analysis. Also, flap survival was evaluated on day 7 using Image-Pro Express. The TMZ group had a significantly greater flap survival area compared to the sham group. On histopathological examination, the two groups showed significant differences. The TMZ group had a higher epidermal thickness. On biochemical examination, there were significantly higher levels of malondialdehyde and myeloperoxidase activity in the sham group, while the TMZ group showed significantly greater glutathione and nitric oxide levels. In the present study, TMZ administration was found to reduce I-R injury macroscopically, histopathologically, and biochemically in a rat epigastric island flap model. Level of evidence: Not ratable.

The effect of coenzyme Q10 on venous ischemia reperfusion injury

BackgroundCoenzyme Q10 (CoQ10) is a lipid-soluble benzoquinone with antioxidant features that make it important in the treatment of ischemia reperfusion injury. In this study, we aimed to investigate the beneficial effect of CoQ10 in the treatment of venous ischemia/reperfusion injury. MethodsEighteen Sprague–Dawley male rats were randomly divided into two equal groups: the control group and an experimental group (n = 9 rats). The experimental group received CoQ10 orally, and the control group received a control diet for 8 wk. An inferior epigastric island flap was raised, and the inferior epigastric vein was clamped for 9 h; the flap was then reperfused. All rats were sacrificed on postoperative day 5. The flap survival rate and levels of CoQ10, malondialdehyde, glutathione, and superoxide dismutase were assessed, and flap tissues were examined under a light microscope (×200 magnification) after being stained with Hematoxylin & Eosin. ResultsThe flap survival rate and levels of CoQ10, glutathione, and superoxide dismutase were significantly higher, but level of malondialdehyde was lower in the experimental group. The mean flap survival rates and plasma levels of CoQ10 were 51% ± 24% and 251 ± 11 ng/mL in the control group, whereas they were 88% ± 7% and 692.8 ± 79.7 ng/mL in the experimental group with statistically significant differences (P < 0.001). Polymorphonuclear leukocyte infiltration was higher, and surface epithelial integrity was more impaired in the control group. ConclusionsWe concluded that CoQ10 supplementation has a beneficial effect on venous ischemia and/or reperfusion injury and improves flap survival rate.

Comparing Different Postconditioning Cycles After Ischemia Reperfusion Injury in the Rat Skin Flap

Ischemic postconditioning is a useful manipulation to reduce the undesirable effects of ischemia-reperfusion (I/R) injury. The beneficial results of this phenomenon against I/R injury have been seen in several flap models. However, there are no published works comparing different postconditioning (post-con) cycles in skin flaps. In this study, we investigated the effectiveness of different post-con cycles in a skin flap model. Epigastric island flap (6 × 3 cm) model which was based on the left superficial epigastric artery and vein was used, and complete 6 hours of ischemia was generated by occlusion of the pedicle. Forty male Wistar rats were allocated into 5 groups (n = 8 in each group). Group 1 (sham group): the elevated skin flap was repositioned without an episode of ischemia. Group 2 (control group): skin flap was elevated and 6 hours of complete ischemia was induced by clamping the pedicle. Group 3 (post-con 1): After ischemia, post-con was performed by 6 cycles of 15 seconds of repeated I/R periods. Group 4 (post-con 2): After ischemia, post-con was performed by 6 cycles of 30 second of repeated I/R periods. Group 5 (post-con 3): After ischemia, post-con was performed by 6 cycles of 60 second of repeated I/R periods. Flap viability was assessed 1 week after the surgical procedure, the necrotic area of the skin flap was measured using image analysis on the computer. The area of flap necrosis was statistically significant between the control and post-con group 4 and group 5, and no statistically significant difference was obtained between the control and post-con group 3. Groups 4 and 5 demonstrated lesser area of flap necrosis than the control group and group 4 was superior to group 5. The results revealed that the post-con applied by means of 6 cycles of 30 seconds yields the best protection against I/R injury in the rat skin flap model.

Effects of Verapamil, Nifedipine, and Daflon on the Viability of Reverse-Flow Island Flaps in Rats

Reverse-flow flaps are preferable in reconstructive surgery due to their several advantages. However, they may have venous insufficiency and poor blood flow. In this study, effects of various pharmacological agents on the viability of reverse-flow flaps were investigated. Forty Sprague-Dawley rats were used. Superficial epigastric artery- and superficial epigastric vein-based reverse-flow island flaps were preferred. The rats were divided into 4 groups. Group 1 was considered as the control group. Group 2 was given verapamil 0.3 mg/kg per day, group 3 nifedipine 0.5 mg/kg per day, and group 4 Daflon 80 mg/kg per day for 7 days. On day 7, viable flap areas were measured, angiography was performed, serum nitric oxide levels were evaluated, and histopathological examination was done.The mean flap viability rate was 67.59% (±13.12259) in group 1, 77.38% (±4.12506) in group 2, 74.57% (±3.44780) in group 3, and 85.39% (±4.36125) in group 4 (P = 0.001). The mean nitric oxide level was 31.66 μmol/dL (±2.42212) in group 1, 51.00 μmol/dL (±2.96648) in group 2, 34.00 μmol/dL (±2.96648) in group 3, and 47.66 μmol/dL (±2.80476) in group 4 (P = 0.001). On angiography, there were vessel dilations and convolutions in group 2; capillaries became noticeable, and anastomotic vessels extended toward the more distal part of the flaps in group 4. Histological examinations showed severe inflammation in group 3 and minimal inflammation and venous vasodilatation in group 2.Verapamil and Daflon in therapeutic doses significantly increased the viability of reverse-flow island flaps. However, nifedipine did not make a significant contribution to the flap viability. The results of this study will contribute to the literature about the hemodynamics of reverse-flow island flaps and guide further studies on the issue.

Comparison of the flap survival with ischemic preconditioning on different pedicles under varied ischemic intervals in a rat bilateral pedicled flap model

The study was undertaken to search whether pedicle selection for ischemic preconditioning (IP) and duration of global ischemia applied after IP influenced efficacy of IP on flap viability in epigastric adipocutaneous island flap with bilateral pedicles in rat model. In total, 159 rats were divided into one control and three (primary, secondary, or bilateral pedicle) IP treatment groups. IP was performed on different pedicles by three cycles of 10 minutes of pedicle clamping and 10 minutes of release. After IP procedure secondary pedicle was ligated in all groups, and flaps were exposed to 0, 1, 2, 4, or 6 hours of global ischemia by clamping primary pedicle. In control groups, after the perfusion of bipedicled flaps for 1 hour, left pedicle was ligated and flaps were exposed to global ischemia as in IP groups. On day 5 post-surgery, tissue samples and topographic measurements were taken. No significant differences in semi-quantitative scorings of polymorphonuclear leukocytes infiltration, chronic inflammation, interstitial edema, neovascularization, VEGF, and CD105 expression levels among groups were found (P > 0.05). Percentages of necrosis were consistently smaller in IP groups compared to controls for the same duration of global ischemia, with exception of the no-ischemia. Area of necrosis was significantly smaller in primary IP group versus secondary IP group in the absence of global ischemia (P < 0.01). In the presence of global ischemia, both primary and secondary pedicle IP groups had significantly smaller percentage of necrosis than controls (P < 0.05) and there was no significant difference between primary and secondary IP groups (P > 0.05). Thus, IP performed on different pedicles may ameliorate flap survival in a comparable fashion, depending on the duration of global ischemia. Secondary pedicle IP was as effective as primary pedicle IP and may be feasible in free flap transfers.

Transcutaneous PCO2 Measurement at Low Temperature for Reliable and Continuous Free Flap Monitoring: Experimental and Clinical Study.

Background:Measurement of transcutaneous oxygen pressure (TcPO2) and transcutaneous carbon dioxide pressure (TcPCO2) has been used for free flap monitoring. Because these values are obtained with sensor probes heated to 44°C, there is potential for low-temperature burns on skin flaps. We measured TcPO2 and TcPCO2 at 37°C in both animals and humans to determine the feasibility and safety of the procedure as a postoperative flap monitoring method.Methods:Twelve epigastric island flaps were elevated in rabbits, and TcPO2 and TcPCO2 were measured at 37°C before and after ligation of the pedicles. In addition, TcPO2 and TcPCO2 at 37°C were measured in healthy men. Subsequently, the method was applied to postoperative monitoring of free flaps in 49 clinical cases.Results:TcPO2 and TcPCO2 values were significantly affected by the experimental flap elevation. A rapid increase in TcPCO2 was observed with both arterial and venous occlusion. In the healthy men, TcPO2 and TcPCO2 were measurable at all skin surface sites. In the clinical cases of free flap transfer, TcPO2 values remained very low for at least 72 hours. TcPCO2 values ranged from 40 to 70 mm Hg for 72 hours in more than 80% of cases. In 2 cases, TcPCO2 values increased to more than 90 mm Hg, and exploration surgery was performed. These compromised flaps were saved by reanastomosis of the veins.Conclusions:Continuous monitoring of TcPCO2 at 37°C can provide objective information and alert doctors and nurses to the need for checking the free flap.

Tadalafil significantly reduces ischemia reperfusion injury in skin island flaps

Introduction:Numerous pharmacological agents have been used to enhance the viability of flaps. Ischemia reperfusion (I/R) injury is an unwanted, sometimes devastating complication in reconstructive microsurgery. Tadalafil, a specific inhibitor of phosphodiesterase type 5 is mainly used for erectile dysfunction, and acts on vascular smooth muscles, platelets and leukocytes. Herein, the protective and therapeutical effect of tadalafil in I/R injury in rat skin flap model is evaluated.Materials and Methods:Sixty epigastric island flaps were used to create I/R model in 60 Wistar rats (non-ischemic group, ischemic group, medication group). Biochemical markers including total nitrite, malondialdehyde (MDA) and myeloperoxidase (MPO) were analysed. Necrosis rates were calculated and histopathologic evaluation was carried out.Results:MDA, MPO and total nitrite values were found elevated in the ischemic group, however there was an evident drop in the medication group. Histological results revealed that early inflammatory findings (oedema, neutrophil infiltration, necrosis rate) were observed lower with tadalafil administration. Moreover, statistical significance (P < 0.05) was recorded.Conclusions:We conclude that tadalafil has beneficial effects on epigastric island flaps against I/R injury.

Transfection of nuclear factor‐kappaB decoy oligodeoxynucleotide protects against ischemia/reperfusion injury in a rat epigastric flap model

Nuclear factor-kappaB (NF-κB) is considered to play an important role in the response to ischemia/reperfusion (I/R) injury in flap surgery. To inhibit NF-κB, synthetic double-stranded oligodeoxynucleotide (ODN) was used as a decoy. The present study aimed to evaluate the suppressive effects of NF-κB against I/R injury of experimental rat flap model. An extended epigastric island flap was raised and ischemia was induced for 3 h. NF-κB decoy ODN (group D) or single-strand ODN (control; group S) was injected via the contralateral artery when the pedicle was clamped. Transfection efficiency was evaluated with fluorescein isothiocyanate (FITC)-labeled ODN. The effects of NF-κB decoy ODN were analyzed in groups D and S, and an untreated group (group N). FITC-labeled ODN was distributed over the entire flap. Mean survival rate of the flap was significantly higher in group D than in the other groups (group D: 57.9%; group S: 31.1%; group N 31.7%; p < 0.005). Injured muscle fibers, neutrophils and the expression of inducible nitric oxide synthase were significantly lower in group D. A real-time polymerase chain reaction also demonstrated a tendency for suppression of tumor necrosis factor-α, interleukin (IL)-1β and IL-6. We show that NF-κB decoy ODN protected against flap necrosis as a result of I/R injury in rats. We also indicate that intra-arterial injection of naked NF-κB decoy ODN is effective for transfection into target organs. Therefore, transfection of NF-κB decoy ODN represents a novel therapeutic strategy for the treatment of flap surgery in I/R injury.

Preventive Effect of Dexmedetomidine in Ischemia-Reperfusion Injury

The aim of this study was to evaluate the effects of dexmedetomidine on ischemia-reperfusion injury of epigastric island flaps of rats. Eighty Wistar rats were divided into 4 groups. After the flap elevation, in group 1, the flaps were sutured back without ischemic insult. Groups 2, 3, and 4 were exposed to ischemia for 12 hours. In groups 1 and 2, saline, in group 3, 10 μg/kg dexmedetomidine, and in group 4, 30 μg/kg dexmedetomidine were administered i.p. 45 minutes before I/R periods. Each group was subdivided further into 2 equal groups (a and b). Tissue samples of groups 1a, 2a, 3a, and 4a were obtained 12 hours after the reperfusion, and those of groups 1b, 2b, 3b, and 4b were obtained after 7 days. The necrotic areas were also calculated. Nitric oxide, malondialdehyde (MDA), and myeloperoxidase (MPO) activity were assessed in the tissue samples. Nitric oxide, MDA, and MPO activity levels in group 2a were significantly higher those in group 1a (P < 0.05). The levels in groups 3a and 4a were lower than those in group 2a (P < 0.05). Nitric oxide, MDA, and MPO activity levels were significantly higher in group 2b compared with group 1b (P < 0.05). The levels were lower in Groups 3b and 4b compared with group 2b (P < 0.05). Flap necrosis area was significantly lower in groups 3b and 4b than that in group 2b (P < 0.05). We conclude that administering dexmedetomidine before I/R periods can reduce ischemia-reperfusion injury of flaps, and it has a beneficial effect on flap survival.

Estudo da ação da estreptoquinase e do alopurinol em retalhos cutâneos em ilha submetidos à isquemia prolongada: estudo experimental em ratos

To establish a relation between the survival rate of island skin flaps submitted to prolonged ischemia and the effect of streptokinase and allopurinol administered after the ischemic period. A total of 48 male Winstar rats, each weighing between 300 and 350 grams,were separated into four groups of twelve as follows: control, allopurinol, streptokinase and association of allopurinol and streptokinase, were submitted to an epigastric island flap dissection followed by epigastric vessel bundle clamping. Flaps remained this way for 8 hours in normothermic mixed ischemia. After the ischemic period, clamps were removed and each rat received the therapeutical scheme proposed for the group by intravenous injections. Flap survival analysis was performed on the seventh post operative day. Variance and descriptive analyses (as a percentage of the necrotic area) as well as Dunnett-T3 multiple comparisons among the 4 groups and median tests were carried out. Rats in the control group presented an average of 79.88% of necrosis in the flap total area; those which received allopurinol presented an average of 64.05% of necrosis whereas the group which received streptokinase showed an average of 55.52% of necrosis. With the association of both drugs, rats presented an average of 54.30% of necrosis in the flap total area. By applying Dunnet test and the median test, it could be verified that, in this study the streptokinase group had the lowest necrosis rate. The systemic administration of streptokinase after 8 hours of normothermic global ischemia resulted in an increased survival rate of epigastric island skin flaps in rats, when compared to the administration of allopurinol, association of the two drugs and the control group.

Effect of platelet glycoprotein IIb/IIIa receptor antagonist on survival of epigastric island flaps in rats with total venous occlusions

We evaluated the effect of tirofiban hydrochloride on the survival of epigastric island flaps in rats that had had all the veins occluded. Male Wistar Albino rats were randomly assigned to control (treated with sterile saline) and experimental (treated with tirofiban hydrochloride 1 mg/kg intravenously) groups. An epigastric island skin flap 3x6 cm was raised in each rat. All veins that drained the flap were ligated to give total venous occlusion. Blood flow was recorded by laser Doppler preoperatively (baseline), immediately after the flap had been sutured back to its original position (acute) and on postoperative days 1 and 3. The degree of necrosis was evaluated on day 3. Mean percentage necrosis and minimum laser Doppler values were compared in the two groups. Total necrosis was evident on day 1 in the control group and on day 3 in the experimental group. Macroscopic evidence was confirmed by histopathological examination. There were appreciable differences in blood flow and in the necrotic area of the flap in the experimental group compared with the control group on both days 1 and 3. Tirofiban hydrochloride might be effective in this flap model.

Flap Monitoring by Transcutaneous PO2 and PCO2: Importance of Transcutaneous PCO2 in Determining Follow-up Treatment for Compromised Free Flaps

The authors conducted a two-part study to determine whether transcutaneous oxygen pressure (TcPO (2)) and transcutaneous carbon dioxide pressure (TcPCO (2)) can be used to monitor flap viability after transplantation. The first part was an animal study in which TcPO (2) and TcPCO (2) were measured in 10 epigastric island flaps subjected to arterial or venous ischemia. The second part was a clinical study in which both were measured in 27 free skin flaps. In the experimental study, TcPO (2) decreased to nearly 0 mmHg after 10 minutes of arterial and venous ischemia. TcPCO (2) increased to 100 mmHg after 60 minutes of either type of ischemia. In the clinical study, congestion was suspected in six flaps on the basis of clinical signs alone. Three congested flaps with TcPCO (2) more than 90 mmHg were selected for intervention. The remaining three congested flaps, with TcPCO (2) 80 mmHg or less, survived completely without further treatment. The TcPO (2) of all treated flaps and of the six flaps not requiring further treatment was 0 mmHg. Results of experimental study indicate that TcPO (2) is more sensitive than TcPCO (2) to flap ischemia. However, results of clinical study suggest that it is very hard to distinguish congested flaps from healthy flaps by TcPO (2) alone. The authors believe that a congested flap with a TcPCO (2) more than 90 mmHg requires further treatment.

Effects of clopidogrel on survival of rat skin flaps

Clopidogrel is a thienopyridine derivative that is chemically related to ticlopidine, which irreversibly inhibits platelet aggregation by selectively binding to adenylate cyclase-coupled adenosine diphosphate receptors on the platelet's surface. In animal models, clopidogrel has been shown to reduce the incidence of both arterial and venous thrombi. In the present study the effects of clopidogrel on the survival of rat epigastric island flaps was researched. Epigastric island flaps of 7x7cm were raised from symphisis pubis to arcus costa with the panniculus carnosus. The experimental group received seven doses of 25mg/kg clopidogrel postoperatively, the first dose given immediately after the suturing of the flaps. The rats were anaesthetised on postoperative day 7 to assess the survival of flaps. The difference between the clopidogrel and the control group was significant (P<0.005). The full-thickness skin samples obtained after the calculation of survival percentages revealed thinning of the epidermis layer and active chronic inflammation in both groups. However, diffuse dilated vessels, extravasated eritrocytes were seen in the clopidogrel group flaps. The results indicated a significant increase in flap survival in rats given clopidogrel. Further research is needed to assess the critical doses of clopidogrel to create optimal flap survival improvement.

Influence of diabetes on critical flaps based on the vascular axis of a sensory nerve

Delayed sural flap based on the vascular axis of the sural nerve has been advocated for coverage of diabetic foot ulcers. In this study we compared the survival of neurovenous and standard inferior epigastric island flaps in diabetic and non-diabetic rats. VEGF concentrations and electrolyte balance of the flaps were also investigated during elevation and on the fifth day to explore the possible mechanisms that influence ischaemia of the flap during the hyperglycaemic state. There were no statistical differences in area surviving between diabetic and control rats for either flap. The VEGF concentrations were also similar in the two flaps in the two groups during elevation. On the fifth day, VEGF concentrations had decreased significantly in all of the flaps. Electrolyte balance paralleled VEGF concentrations. We conclude that flaps based on the vascular axis of a superficial nerve deserve further experimental and clinical attention as potential options for reconstruction of ulcers on diabetic feet.

Protective Effects of Monoclonal Antibody to Intercellular Adhesion Molecule-1 in Venous Ischemia-Reperfusion Injury: Experimental Study in Rats

Flaps with venous occlusion have a decreased survival rate compared with arterial occlusion. It seems that several factors are involved in the etiology of total venous occlusion, including free radicals, edema, thrombosis, and reperfusion injury. In the present study, the authors evaluated the blockage of polymorphonuclear leukocyte endothelial adhesion by using a monoclonal antibody to the intercellular adhesion molecule 1 (ICAM-1) ligand to prevent venous ischemia-reperfusion injury in rat epigastric island flaps. A skin flap (3 x 4 cm) supplied by the superficial epigastric artery and vein was harvested unilaterally in 40 male Wistar rats. Total venous occlusion of the skin flap was achieved. Arterial inflow was left intact. Rats were randomly divided into four groups (n = 10). In Group 1; rats were intravenously pretreated with 0.5 ml of 0.9 percent normal saline 15 min before applying a venous clamp, and the flaps were subjected to 6 hr of venous ischemia. In Group 2; rats were intravenously pretreated with 0.05 mg of monoclonal antibody to the intercellular adhesion molecule 1 (0.20 mg/kg) in 0.5 ml of 0.9 percent normal saline 15 min before applying the venous clamp, and the flaps were subjected to venous ischemia as in Group 1. In Group 3; rats were pretreated as in Group 1, and the flaps were subjected to 8 hr of venous ischemia. In Group 4; rats were pretreated as in Group 2, and the flaps were subjected to 8 hr of venous ischemia. The flaps were assessed histologically and by measuring viable and non-viable areas on postoperative day 7. Flap measurements revealed that blocking the action of ICAM-1 IN VIVO by administering monoclonal antibody significantly attenuated ischemic injury after 6 or 8 hr of venous occlusion.

Angiogenic effects of injected VEGF 165 and sVEGFR-1 (sFLT-1) in a rat flap model

Background. Injections of single-dose vascular endothelial growth factor (VEGF) 165 have been advocated as a therapeutic tool for angiogenesis in ischemic flaps. We challenged this thesis by employing both VEGF 165 and vascular endothelial growth factor receptor-1 (VEGFR-1) (for competitive inhibition of VEGF signal transduction) in different experimental settings of an ischemic rat flap model. Material and methods. 80 isogenic rats were divided in two groups of 40 animals (groups 1A–1D and 2A–2D). The ischemic target was a 7 × 7-cm epigastric island flap, based on the right inferior epigastric pedicle. Group 1 received flap treatment 1 week prior to flap elevation by test substance injection into its flap panniculus carnosus: 1 ml NaCl 0.9% (1A), 1 ml Dulbecco’s modified Eagle’s medium (1B), 1.0 μg VEGF 165 (1C), and 10 μg sFLT-1 with 1.0 μg VEGF 165 (1D). sFLT-1 is a soluble receptor for VEGF and is able to prevent VEGF signaling through the cell surface receptor. Group 2 had the same flap treatment at the day of flap elevation. Results. In group 1C we found the most vital flap tissue, without reaching significance. Compared with group 1D, however, significantly more flap tissue maintained vital. In groups 2A–2D, no significant results were found with respect to flap survival. Conclusions. Local application of single-dose VEGF 165 1 week prior to ischemia dose not have significant clinical angiogenic effects. In this experimental setting, VEGF 165-induced angiogenic effects can be significantly inhibited by adding sFLT1 in vivo. A single-dose of VEGF 165 under ischemic conditions causes no significantly better flap survival in this model.

Effect of the delay phenomenon on survival of rat island skin flaps with total venous occlusion.

Necrosis is an inevitable result in flaps with total venous occlusion even if arterial flow is sufficient. The purpose of this study was to investigate the effect of surgical delay on rat island skin flaps with total venous occlusion, using 20 Swiss albino rats. Two epigastric island flaps were elevated in each rat. Flaps of experimental and control groups were elevated in the same animal. In the experimental group (n=20), flap boundaries were incised down to the fascia and the incisions were sutured as a delay procedure at the first stage. After 7 days, the 3 x 6-cm epigastric island flap was elevated, the inferior epigastric vein was ligated, and was cut under X60 magnification. Then, all flaps were sutured back to their original beds. In the control group (n=20), the same surgical procedure as in the experimental group was repeated without a delay procedure. Viability was assessed at postoperative days 1, 3, and 7. At the end of day 7, all flaps in the control group were totally necrosed; however flaps in the experimental group survived partially. The surviving area ranged between 24 and 74 percent (mean: 60 +/- 15 percent). The differences between the two groups were found to be statistically significant, using Student's t-test ( p<0.005). Surgical delay could not completely save a flap with totally interrupted venous return. Nevertheless, a 60 +/- 15 percent portion of these flaps could survive with the help of a simple delay procedure.

Protective effects of superoxide dismutase against ischemia-reperfusion injury: development and application of a transgenic animal model.

Reperfusion of ischemic tissues can be associated with structural and functional injury, which is referred to as ischemia-reperfusion injury. Superoxide dismutase is an endogenous free radical scavenger that converts toxic oxygen derived free radicals to hydrogen peroxide. With the development of gene cloning technology, the potential of manipulating cells to overexpress endogenous proteins has been realized. Transgenic mice capable of overexpressing superoxide dismutase, and knockout mice in which the gene responsible for its production has been deleted, were used as a model to examine the protective effects of superoxide dismutase against ischemia-reperfusion injury. Epigastric island flaps were elevated in wild-type (control), transgenic superoxide dismutase 1, and knockout superoxide dismutase 1 mice and subjected to ischemic intervals of 0, 3, 6, 9, or 12 hours. Five animals were studied at each time point in each study group. Flap viability was assessed on postoperative day 7. Baseline wild-type flap survival was 100 percent after 3 hours of ischemia and subsequent reperfusion; survival decreased to 21 percent after 9 hours of ischemia. Transgenic mice had significantly higher flap survival than wild-type animals after 6 hours of ischemia and subsequent reperfusion (97.0 versus 85.2 percent) and after 9 hours of ischemia (82 versus 21 percent, p < 0.01). In knockout mice, there was complete flap necrosis after as little as 3 hours of ischemia. This study confirms the protective effects of superoxide dismutase against ischemia-reperfusion injury. In addition, its deficiency results in a dramatic susceptibility to ischemic injury.