Flaps In Rabbits Research Articles

A metabolic investigation of arterialized venous flaps in rabbits using mass spectrometry-based metabolomics.

An arterialized venous flap (AVF) is an ideal choice of flap to repair wounds. However, the survival of these flaps remains the source of some concern. This study used metabolomic analysis to investigate the mechanisms underlying survival in AVF flaps in order to guide the clinical application of these flaps. Thirty-six male Japanese rabbits were randomly divided into a sham group and an AVF group. They were used for histology and hemodynamic investigations. Three days after surgery, tissue samples were analyzed by mass spectroscopy-based metabolomics. The results of the study revealed a reduction in blood flow, infiltration of inflammatory cells, and necrosis of flaps in the AVF group. In addition, notable changes were evident in the levels of several metabolites in the AVF group, including lactic acid, acetoacetic acid, inositol phosphate, arachidonic acid, and other metabolites. Our results indicate that the AVF group experienced changes in several biological pathways, including energy metabolism, cell membrane stability, and inflammatory response. There is a significant metabolic difference between AVFs and physiological flaps. The dysregulation in certain metabolites may be related to the specific hemodynamics and insufficient energy metabolism of the AVFs.

The Effect of Perioperative Dimethyl Sulfoxide Efficacy on Regional and Local Flaps Viability

Background: The purpose of this study was to analyze the effects and results of dimethyl sulfoxide (DMSO) usage on viability and perfusion of local and regional flaps in rabbits, via this study we are going to conclude whether DMSO could be effective after flap operations in human or not. Materials and Methods: Local and regional DMSO spray was used on rabbit’s dorsum flaps immediately after the operation and once per day up to 7 days post-op in 14 rabbits, divided equally to control group (saline solution spray) or experiment group (DMSO spray). The results were compared 3 and 7 days after operations. Results: There were improved results attributed to the DMSO effects regarding flap survival Conclusion: We concluded that topical application of DMSO reduces skin flap ischemia in rabbits and we highly advise the use of it after operations in which skin flaps are created.

Are prostaglandins or calcium channel blockers efficient for free flap salvage? A review of the literature

The free flap failure rate is less than 5%. The responsible mechanisms of postoperative secondary ischemia are mostly vascular. The main postoperative complication leading to flap failure is thrombosis. Different strategies have been reported to improve the reliability of flaps and decrease the risk of partial or total necrosis: thus, pharmacologic agents have been studied to reduce the risk of microvascular thrombosis. The aim of this review was to evaluate the effect of calcium channel blockers and prostaglandins on free skin flap survival. A systematic review of the literature was performed to identify articles studying the efficacy of calcium channel blockers and prostaglandins on free flap survival. After full text reading, eleven articles were finally included. Eight articles investigated the role of prostaglandins in free tissue transfers, two in rats subjects, one in rabbits, five in humans. Two articles studied the effect of calcium channel blockers on free flaps, one in rats subjects, one in rabbits. One article studied in different groups the effect of calcium channel blockers and prostaglandins on free flaps in rabbits. Literature regarding the efficacy of calcium channel blockers and prostaglandins to salvage free flap is poor and mainly based on animal models. Nevertheless, studies on prostaglandins showed a slight efficiency of these molecules for free flap salvage. Results are less reliable for calcium channel blockers and dependent on the molecule used. In conclusion, there is a lack of evidence to use them in clinical practice.

An Alternative Rhinoplasty Technique: Rotational Spreader Flap ("Rabbit Flap").

In modern rhinoplasty, septal cartilage is the most commonly used graft material. It is a big challenge if septal cartilage is insufficient. We present an alternative technique named the "rabbit flap," created from the cephalic portion of the lower lateral cartilage to show its effectiveness on nasolabial angle, nasal axis deviation, and nasal dorsal line. An alternative flap, called a "rabbit flap," is constituted from the cephalic portion of the lower lateral cartilage (LLC). The key for this flap's success is in not cutting the connection between the lateral and medial crus of the alar cartilage. The flap is rotated and placed between the upper lateral cartilage and the septum to ensure a spreader graft effect; it can also be moved forward and backward to adjust the nasal tip rotation. Patients whose minimum width of LLC was 12mm were included in this study. We subjectively evaluated the results of this technique for 24 patients who completed the rhinoplasty outcomes evaluation (ROE) questionnaire and objectively by measuring the nasal axis and nasolabial angles in the preoperative and postoperative first-year periods. There were significant improvements in ROE, nasal axis deviation, and nasolabial angle scores when preoperative and postoperative first-year controls were compared (p<0.001). We also observed no complications. With this technique, we can correct both a nasal tip rotation and a mild nasal axis deviation. Moreover, we can achieve a proper nasal dorsal line and prevent an inverted V deformity. By expanding the internal nasal valve, a functionally effective surgery can be performed. However, the LLC must be strong enough to avoid alar collapse. In light of our results, we believe that the technique we call the "rabbit flap" can be used as an alternative rhinoplasty technique. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of platelet-rich plasma on flap graft survival

Objective To explore the effect of platelet-rich plasma (PRP) on flap graft survival. Methods Two random skin flaps were elevated on the back of the rabbits with spinal symmetry in fifteen healthy rabbits. We selected randomly one side as PRP side, another side as blank control side. And then the autologous PRP was daubed to the basement of the skin flap in PRP side, while the blank control side was treated with normal saline of the same volume. At 3 d, 7 d, and 14 d after the surgical operation, the immunohistochemistry was conducted to detect the microvessel density by CD34, and the the flap graft survival rate was tested and the histological changes of the flaps were observed by HE staining. Results The survival rates of skin flap graft were that the PRP side in 3 d (74.4±4.7)%, while the control side (65.8+ 6.8)%; the PRP side in 7 d (72.4±7.5)%, while the control side (58.5+ 7.0)%; the PRP side in 14 d (74.5±5.0)%, while the control side (65.0±5.4)%. The inflammatory reaction became declining with the extension of time, while density of blood vessels was increasing. In 14 d inflammatory reaction was the lowest and blood vessels’ density was the largest. In all the control sides inflammatory response was obvious than that of the PRP side. CD34 positive count in 3 d PRP side microvascular density (MD) was (13.9±2.0)/HP, controlled side (11.1±1.3)/HP; in 7 d PRP MD was (15.7±1.5)/HP, controlled side (12.1±1.2)/HP; in 14 d PRP MD was (19.6±1.2)/HP, controlled side (12.7±0.8)/HP. There were significant differences in the MD at 3 d, 7 d, and 14 d (P<0.05) between PRP side and control side. Conclusions Platelet-rich plasma is able to promote the survival of random rabbit flap. Key words: Platelet-rich plasma (PRP); Flap

Analyses Using Micro-CT Scans and Tissue Staining on New Bone Formation and Bone Fusion According to the Timing of Cranioplasty via Frozen Autologous Bone Flaps in Rabbits : A Preliminary Report.

ObjectiveThe timing of cranioplasty and method of bone flap storage are known risk factors of non-union and resorption of bone flaps. In this animal experimental study, we evaluated the efficacy of cranioplasty using frozen autologous bone flap, and examined whether the timing of cranioplasty after craniectomy affects bone fusion and new bone formation.MethodsTotal 8 rabbits (male, older than 16 weeks) were divided into two groups of early cranioplasty group (EG, 4 rabbits) and delayed cranioplasty group (DG, 4 rabbits). The rabbits of each group were performed cranioplasty via frozen autologous bone flaps 4 weeks (EG) and 8 weeks (DG) after craniectomy. In order to obtain control data, the cranioplasty immediate after craniectomy were made on the contralateral cranial bone of the rabbits (control group, CG).The bone fusion and new bone formation were evaluated by micro-CT scan and histological examination 8 weeks after cranioplasty on both groups.ResultsIn the micro-CT scans, the mean values of the volume and the surface of new bone were 50.13±7.18 mm3 and 706.23±77.26 mm2 in EG, 53.78±10.86 mm3 and 726.60±170.99 mm2 in DG, and 31.51±12.84 mm3 and 436.65±132.24 mm2 in CG. In the statistical results, significant differences were shown between EG and CG and between DG and CG (volume : p=0.028 and surface : p=0.008). The histological results confirmed new bone formation in all rabbits.ConclusionWe observed new bone formation on all the frozen autologous bone flaps that was stored within 8 weeks. The timing of cranioplasty may showed no difference of degree of new bone formation. Not only the healing period after cranioplasty but the time interval from craniectomy to cranioplasty could affect the new bone formation.

Vaginal reconstruction with two lower abdominal skin flaps in rabbits: histological and macroscopic evaluation

ObjectiveTo evaluate the use of two skin flaps of the lower abdominal wall in the creation of a cylindrical conduit in vaginal reconstruction surgery in rabbits, through macroscopic and histological analysis. Study designAn experimental study was performed in 16 female New Zealand rabbits, consisting of the use of two rectangular-shaped skin flaps of the lower abdominal wall measuring 1cm longitudinally and 3cm transversely anastomosed to each other through continuous suture of the edges of the two flaps to create a tube. Hysterectomy and excision of the vaginal vault were performed, and the skin tube was anastomosed to the remaining vaginal stump with separate points of polyglycolic acid 4.0. Animals were divided into 4 groups according to the euthanasia at 2, 4, 8 and 12 weeks, when after excision of the neovagina, macroscopic and histological evaluation with hematoxylin–eosin and Masson trichrome were performed. ResultsOf 16 operated rabbits, only 1 presented partial abdominal wall dehiscence, not compromising the flap viability. The macroscopic analysis of the vaginal conduit showed that it was kept open throughout the experimental steps, with a good patency and gauge, showing a slight retraction in the skin conduit length of no statistical significance. In the histopathological analysis, a local inflammatory process in the anastomosis was observed, which was larger in the early evaluation but decreased in late evaluations, as well as the local fibrosis process. Integration of the vaginal and skin epithelia was made with no alterations in their primary characteristics. ConclusionThe use of two skin flaps of the lower abdominal wall as a vaginal conduit presented good integration between skin and vaginal tissue with minimal length retraction, kept the patency during evaluations and did not show strictures, presenting good local healing and a low rate of complications.

Monitoring Partial and Full Venous Outflow Compromise in a Rabbit Skin Flap Model

Free flap failure often results from venous thrombosis. The authors developed a rabbit flap model of partial venous obstruction and evaluated four monitoring devices in detecting partial and full venous compromise. Nine skin flaps were elevated on their arteriovenous pedicles in rabbits. The flap was assessed with quantitative Doppler of arterial inflow, transcutaneous oxygen and carbon dioxide tension, near-infrared spectroscopy tissue oxygen saturation, and scanning laser Doppler imaging. After a stable baseline was achieved, the outflow vein was subjected to partial and full venous obstruction followed by release. Pedicle arterial flow decreased significantly from baseline (5.9 +/- 3.0 ml/minute) during partial (4.1 +/- 2.4 ml/minute; 30.5 percent; p < 0.01) and full obstruction (0.3 +/- 0.4 ml/minute; 94.9 percent; p < 0.01). All other measures changed significantly with full obstruction: transcutaneous oxygen tension decreased by 79.6 percent; transcutaneous carbon dioxide tension increased by 69.0 percent; near-infrared spectroscopy tissue oxygen saturation decreased by 35.7 percent; and scanning laser Doppler imaging decreased by 78.8 percent. Laser Doppler imaging was the only noninvasive device that decreased significantly (p < 0.01) with partial obstruction, from 222.8 +/- 77.3 units to 186.5 +/- 73.2 units (16.3 percent). The authors established a venous obstruction flap model and evaluated four clinically relevant monitoring devices during partial and full venous occlusion. All devices detected full occlusion, but only scanning laser Doppler imaging and arterial Doppler detected partial occlusion. Scanning laser Doppler imaging monitoring may allow warning of impending venous obstruction. Near-infrared spectroscopy tissue oxygen saturation varied the least between flaps and therefore may be the most easily interpreted device for full venous occlusion. Both characteristics are important for clinical application.

Magnesium-Based Bone Cement and Bone Void Filler

Bone cement has great potential in craniofacial surgery in the repair of osseous defects secondary to surgery or trauma. This includes the use of bone cement as a bone void filler for full-thickness cranial defects and as augmentation of deficient bones. Ideally, this material should be easily available, biocompatible, resorbable, bone inductive, and have adhesive qualities to bone. Calcium-based bone cements have some of these qualities but have a higher than desirable failure rate. OsteoCrete, a new magnesium-based bone cement and bone void filler, was compared to Norian in critical-sized skull defects and cementing bone flaps in rabbits. Both materials were successful; however, OsteoCrete had a faster resorption and replacement by bone rate than Norian. Bone flap position and apparent stability were also superior with OsteoCrete. There were no adverse reactions to either cement. A magnesium-based bone cement presents with advantages when compared with a comparator calcium-based cement in craniofacial surgery.

Spatial and temporal patterns of bone formation in ectopically pre-fabricated, autologous cell-based engineered bone flaps in rabbits.

Biological substitutes for autologous bone flaps could be generated by combining flap pre-fabrication and bone tissue engineering concepts. Here, we investigated the pattern of neotissue formation within large pre-fabricated engineered bone flaps in rabbits. Bone marrow stromal cells from 12 New Zealand White rabbits were expanded and uniformly seeded in porous hydroxyapatite scaffolds (tapered cylinders, 10–20 mm diameter, 30 mm height) using a perfusion bioreactor. Autologous cell-scaffold constructs were wrapped in a panniculus carnosus flap, covered by a semipermeable membrane and ectopically implanted. Histological analysis, substantiated by magnetic resonance imaging (MRI) and micro-computerized tomography scans, indicated three distinct zones: an outer one, including bone tissue; a middle zone, formed by fibrous connective tissue; and a central zone, essentially necrotic. The depths of connective tissue and of bone ingrowth were consistent at different construct diameters and significantly increased from respectively 3.1 ± 0.7 mm and 1.0 ± 0.4 mm at 8 weeks to 3.7± 0.6 mm and 1.4 ± 0.6 mm at 12 weeks. Bone formation was found at a maximum depth of 1.8 mm after 12 weeks. Our findings indicate the feasibility of ectopic pre-fabrication of large cell-based engineered bone flaps and prompt for the implementation of strategies to improve construct vascularization, in order to possibly accelerate bone formation towards the core of the grafts.

The Effect of Fondaparinux Versus Enoxaparin in the Survival of a Congested Skin Flap in a Rabbit Model

The purpose of this study was to evaluate the effects of fondaparinux, a selective antithrombin III agonist, in comparison to the low-molecular-weight heparin enoxaparin in the survival of a congested skin flap. Eighteen axial-pattern auricular flaps were performed on rabbits using a well-described congested flap model. Animals were randomized into 2 treatment groups, enoxaparin (n = 6) and fondaparinux (n = 6), and a control group (n = 6) that received no treatment. Skin flap survival area was measured postoperatively at 7 and 14 days. The groups that received fondaparinux and enoxaparin had similar mean flap survival areas and were not statistically different. However, both treatment groups significantly increased flap survival compared with controls (P < 0.014). Fondaparinux, like enoxaparin, significantly improves survival of congested flaps in rabbits. Its use instead of enoxaparin may be warranted, given that it eliminates the risk of heparin-induced thrombocytopenia. Further study in humans is warranted.

Sarpogrelate Hydrochloride, an Antagonist of 5-Hydroxytryptamine Receptor, Improves Skin Flap Survival and Suppresses Thrombus Formation in Injured Microvessels of Rabbits

The authors carried out two studies to examine the effects of the 5-hydroxytryptamine receptor antagonist, sarpogrelate hydrochloride (SH), on flap necrosis. The first study measured survival rates and included histologic examination of random-pattern skin flaps in rabbits. The second study assessed the time to complete obstruction of blood flow with the artificial thrombus formation method, and the time for leukocytes to adhere to the endothelium of microvessels in a rabbit-ear chamber. The treatment groups were injected with SH. The survival rates of skin flaps in the SH-treated group were increased significantly. Histologic examination of vessels in the control group revealed that vessels in the deep dermis were obstructed completely by thrombi, whereas such vessels were not obstructed in the SH-treated group. Thrombus formation time and leukocyte adhesion time in the SH-treated group were prolonged and decreased, respectively. Thus, SH maintained flap circulation and promoted flap survival by preventing thrombus formation.

Effect of lyophilized heterologous collagen on new cartilage formation from perichondrial flaps in rabbits: an experimental study.

New cartilage formation originated from perichondrium has previously been researched in many clinical and experimental studies. 1-6 After these studies, the use of perichondrium for the repair of cartilage defects has been used clinically when enhancing neochondrogenesis has been found to be of great value in decreasing the recovery period. Collagen is the major protein of whole connective tissue, and in vitro positive effects of collagen matrices on neochondrogenesis have also been studied before. 7-9 In this experimental study, in vivo effects of heterologous collagen sponge in perichondrial neochondrogenesis were examined in an animal model, and acceleration and enhancement effects were observed.

The Effects of Surgical and Chemical Delay Procedures on the Survival of Arterialized Venous Flaps in Rabbits

The aim of this study was to investigate the efficacy of a surgical delay procedure and a combined surgical and chemical delay procedure on the survival of arterialized venous flaps. Experimental groups included (1) a control group, (2) a surgical delay (4-day and 7-day delay) group, and (3) a combined surgical and chemical (doxazosin mesylate, nitroglycerine patch) delay group. These groups were further divided into subgroups (n = 10) depending on the delay period and the chemical agents. An arterialized venous flap was created on one ear of each rabbit. In the arterialized venous flap, arterial inflow was provided by anastomosis of the central auricular artery to the anterior branch of the central auricular vein and a venous outflow through the anterior marginal vein. In the control group, the arterialized venous flaps without any delay procedure showed complete necrosis of all flaps. In the surgical delay group, the mean percentage survival of arterialized venous flaps was 36.6 percent in the 4-day delay group and 59.7 percent in the 7-day delay group. In the combined surgical and chemical delay group, a 3-day chemical delay followed by a 4-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 81.1 percent in the doxazosin mesylate group, 72.8 percent in the nitroglycerine patch group, and 92.9 percent in a combination group of doxazosin mesylate and nitroglycerine patch. A 3-day chemical delay followed by a 7-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 94 percent in the doxazosin mesylate group, 90.2 percent in the nitroglycerine patch group, and 99 percent in a combination group of doxazosin mesylate and nitroglycerine patch. In conclusion, the surgical delay procedure increased the percentage survival of the arterialized venous flaps in proportion to the delay period. The combination group of surgical and chemical delay procedures had a significantly greater percentage survival than that of the surgical delay group (p < 0.001), and the delay period could be shortened. (Plast. Reconstr. Surg. 102: 1134, 1998.)

The effects of surgical and chemical delay procedures on the survival of arterialized venous flaps in rabbits.

The aim of this study was to investigate the efficacy of a surgical delay procedure and a combined surgical and chemical delay procedure on the survival of arterialized venous flaps. Experimental groups included (1) a control group, (2) a surgical delay (4-day and 7-day delay) group, and (3) a combined surgical and chemical (doxazosin mesylate, nitroglycerine patch) delay group. These groups were further divided into subgroups (n = 10) depending on the delay period and the chemical agents. An arterialized venous flap was created on one ear of each rabbit. In the arterialized venous flap, arterial inflow was provided by anastomosis of the central auricular artery to the anterior branch of the central auricular vein and a venous outflow through the anterior marginal vein. In the control group, the arterialized venous flaps without any delay procedure showed complete necrosis of all flaps. In the surgical delay group, the mean percentage survival of arterialized venous flaps was 36.6 percent in the 4-day delay group and 59.7 percent in the 7-day delay group. In the combined surgical and chemical delay group, a 3-day chemical delay followed by a 4-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 81.1 percent in the doxazosin mesylate group, 72.8 percent in the nitroglycerine patch group, and 92.9 percent in a combination group of doxazosin mesylate and nitroglycerine patch. A 3-day chemical delay followed by a 7-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 94 percent in the doxazosin mesylate group, 90.2 percent in the nitroglycerine patch group, and 99 percent in a combination group of doxazosin mesylate and nitroglycerine patch. In conclusion, the surgical delay procedure increased the percentage survival of the arterialized venous flaps in proportion to the delay period. The combination group of surgical and chemical delay procedures had a significantly greater percentage survival than that of the surgical delay group (p < 0.001), and the delay period could be shortened.

The Effects of Tissue Expansion on the Hemodynamic and Survival Characteristics of Reverse-Flow Island Flaps

The effects of tissue expansion on the hemodynamic and survival characteristics of reverse-flow island skin flaps were investigated in New Zealand White rabbits. The animals were divided into 3 groups of 15: group I (control) had no surgery prior to flap elevation, group II (nonexpansion) had a noninflated expander, and group III (expansion) had an inflated expander of 80 ml. After 3 weeks of expansion, a reverse-flow island flap based on the distal saphenous pedicle was elevated. A series of hemodynamic studies was performed to test reverse venous flow--in particular, valve competence. Besides observing the reverse flow under an operating microscope, the changes in the intravenous pressure were measured at 0, 5, 15, 30, 60, and 120 minutes after flap elevation. Moreover, reverse-flow resistance (RFR) was measured in each group to test the competence of venous valves. At each time interval, the values of intravenous pressure were significantly lower (p < 0.01) in group III than in the groups I and II. However there was no statistically significant difference between group I and group II. The RFR was measured as 126.7 +/- 33.52 mmHg in group I, 59.3 +/- 29.86 mmHg in group II (p < 0.01), and 25.1 +/- 7.68 mmHg in group III (p < 0.01). Ten days after flap elevation the mean survival of group III (100%) was statistically higher than that of group I (57.4 +/- 18.3%; p < 0.01) and group II (81.6 +/- 12.8%; p < 0.05). These findings simply suggest that controlled tissue expansion improves retrograde venous drainage and increases the survival of reverse-flow island flaps in rabbits. Abnormal dilatation of the venous tree and incompetence of the venous valves seem to be the main factors in explaining the decrease in the values of RFR and intravenous pressure in the expanded flaps. The potential mechanisms to explain the effects of tissue expansion, and the clinical implications are discussed.

Experimental investigation of expanded myocutaneous flaps in rabbits

Expansion of the musculocutaneouscutaneous latissimus dorsi (LTD) flap offers the opportunity to preelevate a thin and enlarged muscle flap and still have primary closure of the donor site. Our aim was to examine in an experimental model the viability, the area of expansion, the contractility and histomorphometry of the muscle as a microsurgical unit. In eight rabbits, one LTD muscle was slowly expanded using a 30 cc tissue expander which was overexpanded to a volume of 35 cc. The contralateral LTD muscle served as a control. The area of expansion was measured radiologically by means of metallic muscle markers implanted on the muscle fascia. The in vitro muscle contraction, muscle fibre composition and fibre area were determined. The results indicated: 1) the expanded LTD muscle remained richly supplied by its neurovascular pedicle and the transfer as a free flap should be considered. 2) the muscle markers were unstable and thus planimetrical measurements based on the radiographs were invalid. 3) the contractile properties of the expanded muscle were preserved. 4) histomorphometrical analysis of the cross-sections of the expanded LTD muscles displayed no significant reduction in mean muscle fibre area compared to control fibres. But a significant increase in fast fatigue resistant fibres and connective tissue was found. Conclusion: Expanded muscles may be used as a microvascular unit for dynamic reconstruction. Measurement of the area of expansion by means of muscle markers placed in the muscle fascia is invalid.

Magnetic resonance imaging detection of vascular occlusion of a pedicled muscle flap.

Contrast-enhanced magnetic resonance imaging (MRI) can be a highly sensitive monitor of tissue blood perfusion. This technique has been used to assess blood flow through liver, kidney, and certain tumors, but has not been widely applied to the study of skeletal muscle circulation. In our study, we used a novel scanning software to obtain contrast-enhanced T2*-weighted gradient echo MRI images of pedicled quadriceps muscle flaps in rabbits in order to study images of arterial, venous, and arterio-venous occlusion. We administered an intravenous bolus of gadoteridol contrast agent at the initiation of scanning, which produces a decrease in T2*-signal and improves the sensitivity of measuring blood perfusion. Within 30 seconds of MRI scanning, control flaps with intact pedicles exhibited a rapid decrease in T2*-signal intensity, indicating adequate perfusion of blood through muscle tissue; however, occluded pedicled flaps showed no significant change in signal intensity, indicating lack of blood perfusion. Differences in signal intensities as measured by MRI between occluded and control flaps were statistically significant (P < 0.05). Selective vascular occlusion of either artery alone, or both artery and vein were detected within 15 minutes, whereas selective venous occlusion could be detected after 2 hours. We conclude that MRI has the ability to assess skeletal muscle perfusion, and is capable of noninvasively evaluating a cross-section of tissue in both superficial and buried flaps. MRI, therefore, may have the potential for evaluating perfusion in muscle flaps (including buried flaps), and other disorders of muscle circulation such as compartment syndrome.

Magnetic resonance imaging detection of vascular occlusion of a pedicled muscle flap

Contrast-enhanced magnetic resonance imaging (MRI) can be a highly sensitive monitor of tissue blood perfusion. This technique has been used to assess blood flow through liver, kidney, and certain tumors, but has not been widely applied to the study of skeletal muscle circulation. In our study, we used a novel scanning software to obtain contrast-enhanced T2*-weighted gradient echo MRI images of pedicled quadriceps muscle flaps in rabbits in order to study images of arterial, venous, and arterio-venous occlusion. We administered an intravenous bolus of gadoteridol contrast agent at the initiation of scanning, which produces a decrease in T2*-signal and improves the sensitivity of measuring blood perfusion. Within 30 seconds of MRI scanning, control flaps with intact pedicles exhibited a rapid decrease in T2*-signal intensity, indicating adequate perfusion of blood through muscle tissue; however, occluded pedicled flaps showed no significant change in signal intensity, indicating lack of blood perfusion. Differences in signal intensities as measured by MRI between occluded and control flaps were statistically significant (P < 0.05). Selective vascular occlusion of either artery alone, or both artery and vein were detected within 15 minutes, whereas selective venous occlusion could be detected after 2 hours. We conclude that MRI has the ability to assess skeletal muscle perfusion, and is capable of noninvasively evaluating a cross-section of tissue in both superficial and buried flaps. MRI, therefore, may have the potential for evaluating perfusion in muscle flaps (including buried flaps), and other disorders of muscle circulation such as compartment syndrome.

The effects of lipo-prostaglandin E1 on axial pattern flaps in rabbits.

The effects of lipo-prostaglandin E1 (lipo-PGE1), lipid microspheres containing PGE1, on axial pattern flaps were examined using 12 x 20 cm axial pattern flaps based on the right superficial inferior epigastric vessels on the abdomens of rabbits. The surviving area of the skin flap in the lipo-PGE1 group (0.197 +/- 14.1 cm2; n = 10) was significantly increased (p < 0.02) compared with the saline control group (110.4 +/- 5.5 cm2; n = 10). Changes in pedicle blood flow after lipo-PGE1 administration were determined using an ultrasonic pulsed Doppler flowmeter (n = 5). Blood flow in the artery was increased immediately after administration, and it was maintained for 40 minutes. The surface blood flow at the caudal end of the flap on the nonpedicle side, where it was poor, was measured using laserflowgraphy. Blood flow in the skin flap surface was improved 5 to 15 minutes after lipo-PGE1 administration, and it was maintained for as long as 60 minutes. Venous occlusion of the skin flap was also improved (n = 3). In conclusion, lipo-PGE1 increased the blood flow in the axial pattern flaps, resulting in significant enlargement of the surviving skin flap area.