Estimation of Contralateral Perfusion in the DIEP Flap by Scoring the Midline-Crossing Vessels in Computed Tomographic Angiography.

BACKGROUND: In deep inferior epigastric perforator flap surgery, the amount of perfusion achievable in the contralateral side over a midline is unclear. Predicting contralateral perfusion preoperatively using computed tomographic angiography will allow efficient breast reconstruction with decreased complications. The authors used computed tomographic angiography to determine whether contralateral perfusion is related to blood vessel status across the midline. METHODS: Preoperative computed tomographic angiography scans and intraoperative perfusion in patients who underwent breast reconstruction with a deep inferior epigastric perforator flap between January of 2018 and July of 2018 were checked prospectively. A vessel scoring system was prepared according to vessel density across the flap midline on the scan (grade 0, no visible vessels; grade 1, visible vessels with disconnection or could not be judged as grade 0 or 2; grade 2, definite vessels). Intraoperative flap perfusion was confirmed with indocyanine green angiography. Postoperative fat necrosis was analyzed using ultrasonography. RESULTS: Ninety-four patients were analyzed. Mean maximal contralateral perfusion length was as follows: grade 0, 7.50 ± 1.89 cm; grade 1, 7.93 ± 2.01 cm; and grade 2, 10.14 ± 2.29 cm. Grade 2 had a statistically significantly greater contralateral perfusion length than grade 0 (p < 0.001) and grade 1 (p < 0.001). Fat necrosis occurred in 27.3 percent (grade 0), 19.1 percent (grade 1), and 8 percent (grade 2), which was statistically significant (p = 0.035). CONCLUSIONS: A definite vessel connection across the midline (as in grade 2) in preoperative computed tomographic angiography indicates that contralateral perfusion will be sufficiently achieved. This vessel scoring system would be helpful in predicting flap perfusion and planning the surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.

A Theoretical Model Describing the Dynamics of Venous Flow in the DIEP Flap.

BACKGROUND: The deep inferior epigastric artery flap is an integral component of autologous breast reconstruction. The technical aspects of performing the flap have been well-established. A prior mathematical model suggested using the largest perforator and concluded that the inclusion of additional perforators may decrease resistance and increase flow, but at the downside of increased tissue trauma. Many complications may result from inadequate venous drainage of the flap and the same mathematical concepts may be applied. We attempt to give a mathematical model, based on the physics of flow and properties of circuits, to explain clinical observations regarding venous drainage of the flap and the complications that may arise. METHODS: We compare the different possible venous drainage systems of a perforator flap to a complex circuit with multiple resistances. Multiple venous perforators will be represented by resistances in parallel, while the deep and superficial drainage systems will be represented by a complex circuit loop. RESULTS: Drainage of the flap may be optimized through the deep drainage system if the venous perforators are of sufficient size. Inclusion of additional perforators may decrease resistance and enhance drainage. Salvage procedures may be necessary when the venous perforators are insufficient in size or when there are insufficient connections between the deep and superficial systems. CONCLUSION: A single large sized vessel may provide adequate drainage in most DIEP flaps, while the use of multiple vessels may enhance drainage upon the encounter of smaller vessels. Salvage procedures may be needed to relieve venous congestion as the design of the venous system becomes more complicated.

A Study on the Effects of the Use of Propofol in Experimental Model Inferior Epigastric Island Flap on Ischemia-Reperfusion Injury.

Problems concerning vascular blood flow are the most frequently encountered ones after flap applications. The flap tissue starts to develop ischemia in patients with a vascular blood flow insufficiency. And reperfusion starts in those patients in whom the ischemia is temporary, triggering an ischemia-reperfusion injury depending on the duration of the ischemia. The aim of this study was to evaluate the effect of propofol, which is an anesthetic agent known to have an antioxidant effect and a free radical scavenging feature on the ischemia-reperfusion injury created on an experimental epigastric island flap.Thirty Sprague-Dawley rats were used in the study. The rats were divided into 3 groups of 10 rats each. Inferior epigastric artery-based abdominal flaps were prepared in all the groups. In group 1 (sham), the flap was elevated but no ischemia was applied. In groups 2 (control) and 3 (propofol), the flap was exposed to ischemia for 2 hours after it was elevated. All the rats were sacrificed and biochemical and histopathological assessments were made on the tissue samples taken on the 14th day. As a result of a comparison between the groups, the flap viability rates and the superoxide dismutase, total antioxidant capacity, and catalase values were found to be significantly higher (P < 0.001) in the propofol group while the malondialdehyde and total oxidative stress values were lower (P < 0.001). Based on the data obtained from the present study, the use of propofol was observed to have a protective effect against ischemia-reperfusion injuries in flap surgeries.

Studying the blood pressures of antegrade and retrograde internal mammary vessels: Do they really work as recipient vessels?

BACKGROUND: The proximal ends of internal mammary (IM) vessels are now the most common recipient vessels for breast reconstruction. On the other hand, bilateral deep inferior epigastric artery perforator (DIEP) flaps are often needed according to the territory and the volume required for reconstruction. The usefulness of retrograde IM vessels as second recipients has recently been reported, but there are very few quantitative studies on the hydrodynamics of the retrograde IM vessels. Because the flow is dependent on the pressure differential, the blood pressures of the antegrade IM artery (AIMA), antegrade IM vein (AIMV), retrograde IM artery (RIMA), retrograde IM vein (RIMV), and recirculated intraflap vein (FV) were investigated to solve this question and to confirm the reliability and usefulness of the retrograde IM vessels. METHODS: Ten free flap breast reconstructions were included in this study. The IM vessels were exposed, and the pressures were measured. After recirculation, the FV pressures were measured when the flap was not ischemic or congestive. Systemic blood pressure was also recorded during the whole measurement period. RESULTS: The AIMA and RIMA pressures were 70.4 ± 8.2 mmHg and 54.0 ± 8.6 mmHg (p = 0.000003), respectively, while the systemic pressure was 65.1 ± 10.0 mmHg. The AIMV pressure was always smaller than the RIMV pressure; the mean AIMV pressure was 5.3 ± 1.6 mmHg. In addition, the FV pressure was greater (p = 0.03) than the RIMV pressure (17.7 ± 9.9 mmHg), while the RIMV pressure was 8.7 ± 2.0 mmHg. CONCLUSIONS: Both the RIMA and RIMV are useful and reliable as second recipients for bipedicled free flap transfers. This is a great benefit because it would provide two recipients in one surgical site and would be especially useful in thin patients or patients with previous abdominal scars requiring double pedicled DIEP flaps. LEVEL OF EVIDENCE: Therapeutic Study, Level IV.

Membrane potential governs calcium influx into microvascular endothelium: integral role for muscarinic receptor activation.

In resistance arteries, coupling a rise of intracellular calcium concentration ([Ca(2+)]i) to endothelial cell hyperpolarization underlies smooth muscle cell relaxation and vasodilatation, thereby increasing tissue blood flow and oxygen delivery. A controversy persists as to whether changes in membrane potential (V(m)) alter endothelial cell [Ca(2+)]i. We tested the hypothesis that V(m) governs [Ca(2+)]i in endothelium of resistance arteries by performing Fura-2 photometry while recording and controlling V(m) of intact endothelial tubes freshly isolated from superior epigastric arteries of C57BL/6 mice. Under resting conditions, [Ca(2+)]i did not change when V(m) shifted from baseline (∼-40 mV) via exposure to 10 µM NS309 (hyperpolarization to ∼-80 mV), via equilibration with 145 mm [K(+)]o (depolarization to ∼-5 mV), or during intracellular current injection (±0.5 to 5 nA, 20 s pulses) while V(m) changed linearly between ∼-80 mV and +10 mV. In contrast, during the plateau (i.e. Ca(2+) influx) phase of the [Ca(2+)]i response to approximately half-maximal stimulation with 100 nm ACh (∼EC50), [Ca(2+)]i increased as V(m) hyperpolarized below -40 mV and decreased as V(m) depolarized above -40 mV. The magnitude of [Ca(2+)]i reduction during depolarizing current injections correlated with the amplitude of the plateau [Ca(2+)]i response to ACh. The effect of hyperpolarization on [Ca(2+)]i was abolished following removal of extracellular Ca(2+), was enhanced subtly by raising extracellular [Ca(2+)] from 2 mm to 10 mm and was reduced by half in endothelium of TRPV4(-/-) mice. Thus, during submaximal activation of muscarinic receptors, V(m) can modulate Ca(2+) entry through the plasma membrane in accord with the electrochemical driving force.

Aging increases capacitance and spontaneous transient outward current amplitude of smooth muscle cells from murine superior epigastric arteries.

Large conductance Ca(2+)-activated K(+) channels (BKCa) contribute to negative feedback regulation of smooth muscle cell (SMC) tone. However, the effects of aging on BKCa function are unclear. We tested the hypothesis that aging alters SMC BKCa function in superior epigastric arteries (SEAs) by using perforated patch recording of enzymatically isolated SMCs from 3- to 4-mo-old male C57BL/6 mice (Young) and 24- to 26-mo-old male C57BL/6 mice (Old). SMC capacitance from Young (15.7 ± 0.4 pF; n = 110) was less than Old (17.9 ± 0.5 pF; n = 104) (P < 0.05). SMCs displayed spontaneous transient outward currents (STOCs) at membrane potentials more positive than -30 mV; depolarization increased STOC amplitude and frequency (P < 0.05; n = 19-24). STOC frequency in Young (2.2 ± 0.6 Hz) was less than Old (4.2 ± 0.7 Hz) at -10 mV (P < 0.05, n = 27-30), with no difference in amplitude (1.0 ± 0.1 vs. 0.9 ± 0.1 pA/pF, respectively). At +30 mV, STOC amplitude in Young (3.2 ± 0.3 pA/pF) was less than Old (5.0 ± 0.5 pA/pF; P < 0.05, n = 61-67) with no difference in frequency (3.9 ± 0.4 vs. 3.2 ± 0.3 Hz, respectively). BKCa blockers (1 µM paxilline, 100 nM iberiotoxin, 1 mM tetraethylammonium) or a ryanodine receptor antagonist (100 µM tetracaine) inhibited STOCs (n ≥ 6; P < 0.05 each). Western blots revealed increased expression of BKCa α-subunit protein in Old. Pressure myography revealed no effect of age on SEA maximal diameter, myogenic tone, or paxilline-induced constriction (n = 10-12; P > 0.05). Enhanced functional expression of SMC BKCa-dependent STOCs in Old may represent an adaptation of resistance arteries to maintain functional integrity.

Aging impairs electrical conduction along endothelium of resistance arteries through enhanced Ca2+-activated K+ channel activation.

OBJECTIVE: Intercellular conduction of electrical signals underlies spreading vasodilation of resistance arteries. Small- and intermediate-conductance Ca(2+)-activated K(+) channels of endothelial cells serve a dual function by initiating hyperpolarization and modulating electrical conduction. We tested the hypothesis that regulation of electrical signaling by small- and intermediate-conductance Ca(2+)-activated K(+) channels is altered with advancing age. APPROACH AND RESULTS: Intact endothelial tubes (60 µm wide; 1-3 mm long) were freshly isolated from male C57BL/6 mouse (Young: 4-6 months; Intermediate: 12-14 months; Old: 24-26 months) superior epigastric arteries. Using dual intracellular microelectrodes, current was injected (± 0.1-3 nA) at site 1 while recording membrane potential (Vm) at site 2 (separation distance: 50-2000 µm). Across age groups, greatest differences were observed between Young and Old. Resting Vm in Old (-38 ± 1 mV) was more negative (P<0.05) than Young (-30 ± 1 mV). Maximal hyperpolarization to both direct (NS309) and indirect (acetylcholine) activation of small- and intermediate-conductance Ca(2+)-activated K(+) channels was sustained (ΔVm ≈-40 mV) with age. The length constant (λ) for electrical conduction was reduced (P<0.05) from 1630 ± 80 µm (Young) to 1320 ± 80 µm (Old). Inhibiting small- and intermediate-conductance Ca(2+)-activated K(+) channels with apamin+charybdotoxin or scavenging hydrogen peroxide (H2O2) with catalase improved electrical conduction (P<0.05) in Old. Exogenous H2O2 (200 µmol/L) in Young evoked hyperpolarization and impaired electrical conduction; these effects were blocked by apamin+charybdotoxin. CONCLUSIONS: Enhanced current loss through Ca2+-activated K+ channel activation impairs electrical conduction along the endothelium of resistance arteries with aging. Attenuating the spatial domain of electrical signaling will restrict the spread of vasodilation and thereby contribute to blood flow limitations associated with advanced age.

Tuning electrical conduction along endothelial tubes of resistance arteries through Ca(2+)-activated K(+) channels.

RATIONALE: Electrical conduction through gap junction channels between endothelial cells of resistance vessels is integral to blood flow control. Small and intermediate-conductance Ca(2+)-activated K(+) channels (SK(Ca)/IK(Ca)) initiate electrical signals in endothelial cells, but it is unknown whether SK(Ca)/IK(Ca) activation alters signal transmission along the endothelium. OBJECTIVE: We tested the hypothesis that SK(Ca)/IK(Ca) activity regulates electrical conduction along the endothelium of resistance vessels. METHODS AND RESULTS: Freshly isolated endothelial cell tubes (60 µm wide; 1-3 mm long; cell length, ≈35 µm) from mouse skeletal muscle feed (superior epigastric) arteries were studied using dual intracellular microelectrodes. Current was injected (±0.1-3 nA) at site 1 while recording membrane potential (V(m)) at site 2 (separation distance=50-2000 µm). SK(Ca)/IK(Ca) activation (NS309, 1 µmol/L) reduced the change in V(m) along endothelial cell tubes by ≥50% and shortened the electrical length constant (λ) from 1380 to 850 µm (P<0.05) while intercellular dye transfer (propidium iodide) was maintained. Activating SK(Ca)/IK(Ca) with acetylcholine or SKA-31 also reduced electrical conduction. These effects of SK(Ca)/IK(Ca) activation persisted when hyperpolarization (>30 mV) was prevented with 60 mmol/L [K(+)](o). Conversely, blocking SK(Ca)/IK(Ca) (apamin+charybdotoxin) depolarized cells by ≈10 mV and enhanced electrical conduction (ie, changes in V(m)) by ≈30% (P<0.05). CONCLUSIONS: These findings illustrate a novel role for SK(Ca)/IK(Ca) activity in tuning electrical conduction along the endothelium of resistance vessels by governing signal dissipation through changes in membrane resistance. Voltage-insensitive ion channels can thereby tune intercellular electrical signaling independent from gap junction channels.

Monitoring microcirculatory changes in the deep inferior epigastric artery perforator flap with laser Doppler perfusion imaging.

Microcirculatory changes were monitored in 20 deep inferior epigastric artery perforator (DIEAP) flaps during unilateral breast reconstruction until the seventh postoperative day using laser Doppler perfusion imaging. Measurements were recorded according to the zonal classification by Scheflan and Dinner. The cutaneous territory zone IV was discarded during insetting due to marginal circulation. The highest perfusion levels were found the first postoperative day for both zones I and III. Postoperative perfusion values were significantly higher for these zones compared with zone II. Immediately after revascularization, zone I was significantly better perfused than both II and III. However, the perfusion in zone III stabilized at the level of zone I in the postoperative phase. Evaluating microcirculatory changes in the DIEAP flap with laser Doppler perfusion imaging showed that zones I and III have higher perfusion levels than zone II in the postoperative phase.

The extraperitoneal laparoscopic TRAM flap delay procedure: an alternative approach.

INTRODUCTION: Ligation of the deep inferior epigastric vessels prior to transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction (delay procedure) was introduced to augment vascularity to the island flap through improved superior epigastric flow, thus decreasing flap morbidity. There are various surgical approaches described, including open and laparoscopic approaches, for ligation of inferior epigastric arteries. We describe an extraperitoneal laparoscopic technique (EPLT) and the outcomes of the procedure. METHODS: All patients who underwent EPLT prior to TRAM flap construction between July 2006 and December 2008 were included in the study. Data were analyzed retrospectively from a prospectively collected database. RESULTS: The study group included 11 female patients with mean age of 55 years and mean body mass index (BMI) of 34.4 kg/m(2). There were no conversions to open procedure. Ten patients had bilateral ligation of inferior epigastric arteries, and one patient had it only on one side. There were no complications related to the procedure. CONCLUSION: Extraperitoneal laparoscopic technique as a delay procedure for TRAM flap reconstruction is safe and feasible with no morbidity related to surgery.

Radial artery as a graft for coronary artery bypass grafting.

The radial artery (RA) graft was revived in late 1980 s when it was found that the graft was patent 13-18 years after coronary artery bypass grafting (CABG) after improvement of the technique in harvesting and the use of calcium-channel blockers. Recently, the RA became a reasonable alternative to the saphenous vein (SV) graft with the trend toward complete arterial revascularization and more frequent off-pump CABG to avoid aortic manipulation. To improve the quality of the RA conduit, harvesting technique and topical and systemic antispasmodic medication are important. The RA should be grafted to severe proximal stenosis (>90%) in the native coronary arteries to avoid flow competition, especially in the right coronary territory. The RA graft could be used as an aortocoronary or composite configuration with similar graft patency. Early graft patency of the RA conduit was as good as other arterial grafts, and better than SV graft in the circumflex and right coronary territories, in many studies, especially in diabetic patients. Long-term results of graft patency and cardiac-event-free survival compared with SV graft are still controversial in randomized controlled trials, probably because the incidence of flow competition and the definition of graft patency varied.

Perfusion dynamics of free DIEP and SIEA flaps during the first postoperative week monitored with dynamic infrared thermography.

Perfusion dynamics of 16 free DIEP flaps and 4 free SIEA flaps were studied during the first, third, and sixth postoperative day using dynamic infrared thermography (DIRT). For both flap types the zone positioned over the perforator is perfused first, followed by the adjacent ipsilateral zone, and finally the contralateral zones. Perfusion of the subdermal plexus of all zones preceded the perfusion of the subcutaneous layer of all zones. While the initial hyperemia subsided with time, the total number of hot spots increased with time. Perfusion of free DIEP and SIEA flaps during the first postoperative week is a dynamic process. The perfusion shows a stepwise progression at the level of the subdermal plexus and at the level of the subcutaneous layer each with its own time sequence and with the midline as an area of resistance for circulation.

Interindividual variability of the SIEA Angiosome: effects on operative strategies in breast reconstruction.

BACKGROUND: The vascular territory of the superficial inferior epigastric artery (SIEA) remains to be clarified. The SIEA flap has traditionally been classified as a hemiabdominal flap, but recent evidence points to the fact that a sizable superficial artery is capable of supplying the entire abdominal ellipse. METHODS: Twenty-five patients who met the anatomical criteria for undergoing SIEA flap surgery were studied. The abdominal flap was raised on a superficial inferior epigastric pedicle; the dominant musculocutaneous perforators were preserved and clamped above the abdominal fascia on either side. The vascular territory of the superficial epigastric artery and the contribution of the deep epigastric system were visualized using laser-induced fluorescence of indocyanine green. The surgical technique was modified (SIEA, deep inferior epigastric perforator, or bipedicle) based on perfusion measurements and the indication for surgery. RESULTS: The SIEA vascular territory did not cross the midline in 16 patients (64 percent), and ranged from 0 percent (two patients) to the entire abdominal ellipse (five cases). Fourteen patients (56 percent) were operated on with a unipedicle SIEA flap, five patients (20 percent) were operated on with a bipedicle flap, and in six (24 percent), a conventional deep inferior epigastric perforator flap was used. As a SIEA flap was originally intended in all patients, intraoperative perfusion measurements changed the surgical plan in 11 patients (44 percent). CONCLUSIONS: The SIEA angiosome is variable and ranges from 0 to 100 percent of the lower abdominal flap. Intraoperative perfusion measurements are indispensable for evaluating the sufficiency of this pedicle for tissue transfer, especially if the contralateral flap zones are needed for reconstruction.

A theoretical model describing arterial flow in the DIEP flap related to number and size of perforator vessels.

BACKGROUND: The deep inferior epigastric perforator flap is rapidly becoming a more widely employed method of autologous breast reconstruction. The technical considerations involved in the execution of the flap are many and include the selection of perforators to be incorporated in the flap. We attempt to give a mathematical explanation, based on the physics of flow through vessels and the properties of circuits with multiple resistances in parallel, for the clinical observations which have been arrived at through clinical experience. METHODS: We compare the system of perforators to a circuit with multiple resistances in parallel. Each of these resistances represents a perforator vessel. In the event that there is only one perforator vessel, this simplifies to a single resistance in series with the capillary bed perfusing the flap. RESULTS: The flow through the flap is optimized by incorporation of the largest diameter perforator. Inclusion of other smaller perforators in addition to the largest diameter perforator will reduce the overall resistance, but this reduction in resistance is dependent on the diameter of the additional perforator and may not be worth the additional trauma of dissection and increased operative time. Incorporating several smaller perforators at the expense of excluding the largest diameter perforator appears to increase the overall resistance, unless the smaller perforators are only slightly smaller. CONCLUSIONS: We conclude that the best perfused flap involves use of the largest diameter vessel, that although adding additional perforators will decrease the resistance and increase flow, the magnitude of the benefit depends largely on the calibre of the additional perforator, and that this benefit needs to be weighed against the downside of increased muscle and facial trauma.

Histologic study of coronary, radial, ulnar, epigastric and internal thoracic arteries: application to coronary artery bypass grafts.

The biometry and the histology of coronary, radial, ulnar, epigastric and internal thoracic arteries were studied in order to investigate the cause of their occlusions in coronary bypass grafts and to improve the results of these bypass grafts. These various arteries were removed from 40 anatomical specimens (27 males and 13 females). We found a correlation between the internal calibers of the ulnar and coronary arteries in males. Intimal changes and the presence of atheromatous plaque were observed in coronary, radial and ulnar arteries, but never in the internal thoracic artery. Like coronary arteries and their branches, radial, ulnar and epigastric arteries are muscular arteries and ageing results in thickening of the intima, which becomes fibrotic with migration of myocytes from the media and duplication of the internal elastic lamina. The media becomes fibrous, hypertrophic or atrophic. In contrast, the internal thoracic artery is an elastic artery, like the aorta. Ageing is characterized by loss, over a variable extent, of one or several elastic laminae of the media and more marked intimal thickening. Although anatomically, the caliber of radial, ulnar, and epigastric arteries remains adapted to that of coronary arteries, the long-term patency of radial, ulnar and epigastric arteries used as grafts is related to their histological characteristics.

Isolated perfusion of a tubed superficial epigastric flap in a rodent model.

BACKGROUND: Isolated perfusion models can yield important data regarding metabolism of the skin. An effective model must remain stable during perfusion but respond appropriately to metabolic and vascular stimuli. We describe the design and characterization of a tubed superficial epigastric isolated perfusion flap. MATERIALS AND METHODS: Tubed superficial epigastric flaps were created in 20 male Sprague Dawley rats. Forty-eight hours later the femoral vessels were cannulated and the flaps were perfused using a Krebs-Heinseleit buffer containing albumin for a period of 2 h. In five of the flaps norepinephrine and acetylcholine were added sequentially to the perfusate to determine vascular reactivity. In a further four flaps insulin (20 U/liter) and iodoacetate (5 mM) were added to the perfusate to confirm that the flap was metabolically active and reactive. Venous outflow was collected at regular intervals and analyzed for electrolytes, lactate, and glucose content. Vascularity and skin perfusion were characterized using barium microangiography and methylene blue dye injection. RESULTS: This flap model was found to be stable in terms of arterial pressure, electrolyte levels, and lactate production over the perfusion period. Norepinephrine caused a sharp increase in vascular resistance, which was reversed by administration of acetylcholine. Lactate production increased appropriately with the addition of insulin to the perfusate with a rapid decline following addition of the glycolysis inhibitor iodoacetate. There was no leakage of perfusate or significant swelling of the flap during the perfusion. CONCLUSIONS: The tubed superficial epigastric artery flap makes an effective model for isolated perfusion studies of the skin with a wide range of experimental applications.

Axial pattern composite prefabrication of high-density porous polyethylene: experimental and clinical research.

Currently, various alloplastic materials are being used for reconstruction of three-dimensional structures, and high-density porous polyethylene is so far the best and the most commonly used material. Various indications for high-density porous polyethylene have been defined for closure of craniofacial defects, correction of congenital anomalies, and aesthetic augmentations. A common property of various studies published so far is that after being fixed to the bone or underlying structures, high-density porous polyethylene has been covered primarily or by skin flaps. For reconstruction of complex three-dimensional structures such as the ear and nose, the success of current methods is limited by the thinness and pliability of the skin flap. In this study, the authors' aim was to investigate the graftability of high-density porous polyethylene after prefabrication with an axial pedicle and to explore possible clinical applications in light of the new data obtained. In the experimental study, three-dimensional implants (rectangular prism) carved from high-density porous polyethylene were prefabricated using bilateral superficial epigastric arteries and veins of 25 New Zealand rabbits. After a waiting period of 2 to 6 weeks in five groups, control samples were obtained and the prefabricated implants that had been left in place were directly grafted. The results showed that high-density porous polyethylene was vascularized 75 percent after 4 weeks and 90 percent after 5 weeks, and 95 percent of the grafts had survived after 8 weeks. In the clinical study, three nose defects, three ear defects, and one hard palate defect in seven patients ranging in age from 21 to 72 years were reconstructed using the same method. High-density porous polyethylene has been prefabricated and directly grafted for the very first time on a clinical basis. No serious complications have been observed, except for minimal graft loss in two patients. It is obvious that full-thickness skin grafts that are thinner than flaps will adapt better to the fine details of high-density porous polyethylene and will highly increase the detail obtained in the reconstruction of three-dimensional defects.

Pulsed magnetic fields applied to a transferred arterial loop support the rat groin composite flap.

Pulsed magnetic fields have been shown to stimulate neovascularization in the authors' laboratory. The rat groin composite flap was used to create a prospective randomized trial to test the effectiveness of these pulsed magnetic fields. The skin paddle to this flap is highly consistent, and the authors proposed using the flap to study how pulsed magnetic fields affect composite flap survival when the dominant vessel to the flap is divided and flap survival becomes dependent on a transferred vessel loop. Forty-three rats had the tail artery microsurgically anastomosed to the femoral artery and placed between the groin musculature and the abdominal skin. Pulsed magnetic energy of 1 gauss was applied for 8 (n = 14) or 12 (n = 8) weeks to the experimental groups. Control groups were treated in a comparable manner for 8 (n = 16) or 12 (n = 5) weeks. After the 8 or 12 weeks, all groups had an 8 x 4-cm skin flap raised, and the superficial epigastric artery, the main feeding vessel, was ligated. After 5 days, the total area of the flap and the area of necrosis were traced onto velum paper for each rat. The percent survival was calculated per rat, and a mean survival percentage was calculated per group. The experimental animals treated with pulsed magnetic fields for 8 weeks had statistically significant improved flap survival over the control animals. The study provides evidence that pulsed magnetic energy stimulates angiogenesis and suggests a possible use of this modality to create island vascular flaps in otherwise random vascular territories.

Thoracoumbilical flap: experience with 33 cases.

From August 1996 to June 2000, 33 free thoracoumbilical flaps were transferred to reconstruct a variety of soft-tissue defects. The size of the flaps ranged from 10 to 40 cm in length and 8 to 25 cm in width. The blood supply to the skin island came from the largest periumbilical perforator of the deep inferior epigastric vessels. The main indications were complex extremity trauma or soft-tissue tumor resection with extensive skin loss, either acute or postprimary. The overall success rate was 100 percent (33/33). The donor area was closed directly in 10- to 12-cm-wide flaps, leaving an inconspicuous scar. Larger flaps required skin grafting. After a 2-year follow-up, all flaps have healed uneventfully and donor abdominal morbidity is minimal.

Simultaneous use of bilateral caudal superficial epigastric axial pattern flaps for wound closure in a dog.

A neutered male German shorthaired pointer sustained severe bite wounds to the left caudal flank and thigh area. Thorough wound lavage and debridement was performed immediately and also three days after presentation. Daily wound dressing resulted in the production of a mature granulation tissue bed. Prior to wound closure, colour flow Doppler ultrasonography was used to confirm blood flow through the right and left caudal superficial epigastric arteries and veins. Sixteen days after presentation, right and left caudal superficial epigastric axial pattern flaps were simultaneously elevated to cover the defect. The right flap was elevated as an island flap, rotated 120 degrees and used to cover the caudodorsal aspect of the defect. The left flap was elevated and rotated dorsally to cover the cranioventral aspect of the defect. Ninety per cent wound coverage was achieved and flap survival was total. The donor site defect was closed primarily and no dehiscence occurred. Three months postsurgery, the entire defect was closed and limb function was normal.