Timing, magnitude, and utility of surgical delay in the TRAM flap: I. Animal studies

Comparison of subdermal and perforator delay techniques on a rat flap model

Background

In this study, we investigated the subdermal and perforator delay phenomena as a method to improve flap survival.

Materials and Methods

In this experimental study, we used 24 rats in three groups. In the control group, the dorsal flaps were elevated and reinserted back to their place. In the experimental groups, we practiced the delay phenomena with two different techniques. In the first experimental group, cranial and lateral side incisions were performed; however, the flaps were not cut-off from the underlying fascia. In the second experimental group, we placed a silicon sheet under the planned flap to cut-off the circulation from the perforator vessels. Four weeks after the delay procedure, the flaps were raised completely and reinserted back to their place.

Results

The average of necrotic area in the control group was 21.9% (±7.70). There was no necrosis in both experimental groups (P < 0.0001). Histological examination revealed that collagen density in both of the experimental groups was increased in comparison to the control group, it has only been found a significant first experimental group (P = 0.0315). We have not found any significant difference in lymphocyte density between the groups. Angiographic imaging has showed an increase in the vascular density in the flaps of the first experimental group.

Conclusion

We believe that both of these delay techniques can be adapted to clinical applications and used safely to increase flap survival.

Visualized identification of the maximal surgical delay effect in a rat flap model

Currently, experimental evidence suggests that the surgical delay can increase flap survival area, but its effect may decrease if the optimal delay period is missed. The aim of this study is to establish a sensitive and objective modality based on the visualized and individualized infrared thermography for identifying the maximal surgical delay effect. A rectangular three-angiosome flap was designed on the unilateral dorsum of the rat. Ninety-six rats were randomly divided into six groups according to the various delay time. Both the relative temperature and the relative temperature ratio were measured by the infrared thermography. Arterial density, number of vessels >0.1 mm in diameter, microvessel density, VEGF concentration, and flap viability were measured. Receiving operating characteristic curve with the highest Youden-Index was used to detect and identify an optimal cutoff point of the relative temperature ratio in the maximal surgical delay effect. The criteria for identifying the flap maximum delay effect based on the infrared thermography included the surface of the postdelayed flaps presented white color (higher temperature) instead of the red and white pattern of the normal skin and the optimal cutoff point of the relative temperature ratio was ≥1.17 with a sensitivity of 84.6% and a specificity of 77.3%. Instead, the sensitivity and specificity of the conventional method based on the delay time were 38.5 and 90.9%, respectively. Infrared thermal imaging can accurately identify the maximum delay effect when combined with the relative temperature ratio.

The protective effect of cilostazol on transverse rectus abdominis myocutaneous flap in rats

OBJECTIVE

Transverse Rectus Abdominis Myocutaneous (TRAM) flap is commonly used in breast reconstruction. The aim of this study is to demonstrate the effects of cilostazol on TRAM flap viability in a rat TRAM model.

METHODS

Twenty-four Wistar rats were used. They were divided into four groups. Rats in Group 1 were applied TRAM flap. In Group 2, cilostazol 30 mg/kg was administered to rats via oral gavage 3 hours before the flap surgery. After the flap surgery, cilostazol 30 mg/kg was administered via oral gavage twice a day for 7 days. In Group 3 before the flap surgery, cilostazol 30 mg/kg was administered via oral gavage twice a day for 7 days, and treatment continued for 7 more days after the flap surgery. In Group 4 before the flap surgery, cilostazol 30 mg/kg was administered via oral gavage twice a day for 7 days and treatment was discontinued after the flap surgery.

RESULT

The mean necrosis rate in Group 1 was 41.69%, in Group 2 it was 27.0%, in Group 3 it was 6.66%, and in Group 4 it was 11.2%. The necrosis rate in Group 1 was found to be statistically significantly higher than other groups (p < .01), the necrosis rate in Group 2 was found to be statistically significant higher than Groups 3 and 4 (p < .01), and the necrosis rate in Group 4 was found to be statistically significant higher than Group 3 (p < .01).

CONCLUSION

Cilostazol treatment seemed to increase the viability of TRAM flap, especially when administered as adjuvant therapy.

Treatment of posttraumatic equinus deformity and concomitant soft tissue defects of the heel

BACKGROUND

To evaluate the operative method and clinical outcome for the treatment of posttraumatic equinus deformity and concomitant soft tissue defect of the heel.

METHODS

Between June 2006 and May 2010, seven cases of posttraumatic equinus deformity and concomitant unstable scar or ulcer of the heels were treated by using a hinged Ilizarov apparatus and reversed sural fasciocutaneous island flap transfer. Achilles tendon lengthening was also done in all patients. The average duration of follow-up was 21 months. The sizes of sural flaps were from 7 cm × 6 cm to 10 cm × 9 cm. Two weeks after the flap transfer, distraction of the Ilizarov fixator was initiated to gradually correct the equinus position of the foot.

RESULTS

Results were evaluated by using the following criteria: (1) the degree of active dorsiflexion of the ankle, (2) the total active range of motion of the ankle, and (3) walking ability and flap durability. For active dorsiflexion of the ankle, the results were good in three patients and fair in four patients. For range of active motion of the ankle, the results were good in five patients and fair in two patients. For walking ability and flap durability, the results were good in six patients and fair in one patient.

CONCLUSION

This study showed that posttraumatic equinus deformity accompanied by soft tissue defect of the heel can be treated effectively with Achilles tendon lengthening, reversed sural fasciocutaneous island flap transfer, and a hinged Ilizarov technique.

Use of expanded reverse sural artery flap in lower extremity reconstruction

Coverage of defects of the distal third portion of the leg and foot remains a challenge for surgeons. The difficulty results from the limited mobility and availability of the overlying skin, the weight-bearing requirements, and the relatively poor circulation of the skin. From January 2008 to December 2009, 10 patients had defects of the foot and ankle covered using the 2-stage expanded reverse sural flap. Of these 10 patients, 6 had at least 1 risk factor for compromised wound healing, such as diabetes mellitus, peripheral arterial disease, venous insufficiency, tobacco smoking, or age older than 40 years. Flap necrosis was observed in only 1 patient (10%). Venous congestion was noted in 2 patients (20%) by the third postoperative day, 1 of whom responded to postural elevation of the extremity and 1 to medicinal leech therapy. Although it is a 2-stage procedure that requires wound dressing during the expansion, we strongly suggest the use of the expanded reverse sural flap for defects too large to be primarily closed, especially in patients older than 40 years with risk factors such as diabetes mellitus, peripheral arterial disease, or venous insufficiency.

Comparison of two different vascular delay methods in a rat cranial epigastric perforator flap model

The effectiveness of vascular delay in transverse rectus abdominis muscle flaps has been demonstrated in many studies. In deep inferior epigastric perforator flaps, however, the effectiveness of ligation of deep versus superficial epigastric vessels in producing delay is unclear. Using a rat model, we compared ligation of deep and superficial vessels with each other and with a (nondelayed) control group (n = 10). One vascular delay group (n = 10) had ligation of the contralateral cranial epigastric vessels (homolog to the human deep inferior epigastric vessels); the other (n = 10) had ligation of contralateral superficial inferior epigastric vessels. One week later, cranial epigastric perforator flap elevation was performed. Both vascular techniques were effective in producing delay, and there was no statistically significant difference between the 2 groups. Ligation of superficial inferior epigastric vessels, deep inferior epigastric vessels, or both, at least 1 week prior to the deep inferior epigastric perforator flap elevation may increase the usable skin paddle area in humans.

Fibrin-embedded administration of VEGF plasmid enhances skin flap survival

The aim of the present study was to experimentally evaluate whether topical fibrin-mediated administration of a vascular endothelial growth factor (VEGF)-A plasmid to the wound bed can protect skin flaps from necrosis. A plasmid expression vector containing the VEGF-A cDNA was constructed. The plasmid was then administered to the wound bed of rat abdominal skin flaps in a fibrin sealant. The percentage of viable, ischemic and necrotic tissue was assessed postoperatively as a baseline and after 3 and 7 days using digital surface area morphometry. Laser Doppler imaging of the flaps and VEGF-A Western blot analysis of flap tissue were performed to assess angiogenesis and VEGF-A tissue levels. Flaps treated with VEGF plasmids in the presence of uptake enhancing Lipofectamine transfection reagent increased flap survival 7 days postoperatively significantly associated with markedly elevated tissue perfusion and enhanced tissue VEGF-A protein expression. Our results indicate that topical fibrin-mediated administration of a VEGF-A plasmid may serve as an alternative to previous strategies in treating ischemic skin flaps. The suggested therapeutic approach is easily applicable and inexpensive in preparation. Thus, this protocol may also enhance wound healing in posttrauma skin lacerations or in skin grafts.

Effect of Hydrostatic Dilation on Flap Viability of the Transverse Rectus Abdominis Musculocutaneous Flap Model in Rats

BACKGROUND

The technique of intraoperative vessel hydrostatic dilation is sometimes used to facilitate microvascular anastomosis and prevent vasospasm. Currently, delay procedures remain a reliable method of maximizing flap survival. The authors aimed to increase rat transverse rectus abdominis musculocutaneous (TRAM) flap viability by imitating the physical effect of a surgical delay procedure with hydrostatic dilation.

METHODS

Forty-five male Sprague-Dawley rats were randomly assigned to one of three TRAM flap groups (15 rats in each group): the control group, the delay group, and the hydrostatic dilation group. The surgical delay procedure was performed by division of right-sided cranial epigastric vessels and contralateral superficial inferior epigastric vessels. While elevating the flap, hydrostatic dilation was performed to the cranial epigastric artery and vein with a mean pressure of 250 mm Hg. The groups were compared by means of microangiography and survival ratio of TRAM flaps and mean artery lumen area, mean vein lumen area, and mean artery wall area of the flap pedicle 48 hours after elevation.

RESULTS

There was a significant difference between the control and hydrostatic dilation groups in favor of surface area viability and angiographic assessment (p < 0.01). Surgical delay has traditionally been accepted as the most reliable method of enhancing flap viability. No significant difference was revealed between the surgical delay and hydrostatic dilation groups (p > 0.05). In the hydrostatic dilation group, compared with the control group, an increase in vein diameter, a thinning of the artery wall, and an increase in lumen diameter were observed.

CONCLUSIONS

The physical effect of blood flow is achieved acutely with hydrostatic dilation. This simple, dependable, one-stage hydrostatic dilation procedure can be used in clinical applications.

Selective Percutaneous Desiccation of the Perforators with Radiofrequency for Strategic Transfer of Angiosomes in a Sequential Four-Territory Cutaneous Island Flap Model

BACKGROUND

Research in prevention of partial flap necrosis has recently concentrated on extending the safe length of a flap by ligating vessels of known territories. To advance this approach one step further, the authors decided to reveal the least invasive surgical strategy for transfer of angiosomes.

METHODS

The study was arranged into three experiments. In the first experiment (n = 17 rabbits), a cutaneous island flap model spanning four adjacent vascular territories was developed. In the second experiment (n = 15 rabbits), the flap model was used to test the possibility of desiccating those vessels supplying the angiosomes to be captured percutaneously with radiofrequency. The delay procedures were performed by means of minimal skin incisions, and the flaps were elevated after a 2-week delay period. In the third experiment, the effectiveness of selective interference of these pedicles was compared to minimize the number of target vessels for successful transfer of angiosomes.

RESULTS

The mean surviving area of the new flap model was 63 +/- 2 percent. The mean surviving flap area was 97 +/- 3 percent for the endoscopy equivalent technique and 94 +/- 4 percent for radiofrequency delay. The results were statistically insignificant between these two groups. In experiment 3, comparison of the results yielded a statistically insignificant difference for flap survival area among all four of the groups.

CONCLUSIONS

An alternative flap model is introduced for future investigation of the vascular delay process. Percutaneous desiccation of the perforators with radiofrequency was found to be a reliable method, and selective desiccation of the perforator(s) was as efficient as destruction of all vascular sources other than the pedicle.

Vascular Delay Revisited

The technique of vascular delay has been used by plastic surgeons for nearly 500 years and has proven useful for reliably transferring tissue and allowing for a greater volume of tissue to be reliably harvested. Delay procedures are an essential plastic surgical tool for a variety of aesthetic and reconstructive procedures. Despite the widespread use of vascular delay procedures, the mechanism by which this phenomenon occurs remains unclear. A number of groups have exhaustively examined microvascular changes that occur during vascular delay. Theories have been proposed ranging from the dilation of choke vessels to changes in metabolism and new blood vessel formation. Inherent in these theories is the concept that ischemia is able to act as the primary stimulus for vascular changes. The purpose of this review is to revisit the theories proposed to underlie the delay phenomenon in light of recent advances in vascular biology. In particular, the participation of bone marrow-derived endothelial progenitor cells in the delay phenomenon is explored. Greater understanding of the role these cells play in new blood vessel formation will be of considerable clinical benefit to high-risk patients in future applications of delay procedures.

The Effect of Hyperbaric Oxygen Therapy on the Delay Procedure

BACKGROUND

This study evaluates the possibility of enhancing the beneficial effect of the delay procedure by using hyperbaric oxygen therapy, and the possibility of lessening the time required for maximal effect of delay procedure.

METHODS

Eight male Wistar rats were used in each of 10 groups. The surgical delay method was applied to the caudally based dorsal rat flap by incising the longitudinal borders and undermining the flap. In the first five groups, 3-, 7-, 10-, 14-, and 21-day delay periods were applied, and in the other five groups, hyperbaric oxygen therapy was applied during the delay periods. Blood circulation was measured with a laser Doppler flowmeter, and flap survival lengths were recorded. Histological analysis for vascular counting and determining vascular areas and microangiographic analysis for monitoring vascular status were performed.

RESULTS

In addition to the flap viabilities being increased, the maximum effect of the delay procedure could be achieved earlier with hyperbaric oxygen therapy. Blood circulation in the flaps, vascular counts, and vascular areas were increased by applying hyperbaric oxygen during the delay period. Microangiographic results confirmed the beneficial effect of hyperbaric oxygen treatment.

CONCLUSIONS

Hyperbaric oxygen treatment during the delay period can lessen the time period needed for the delay procedure and increase the effect of the delay itself.

New developments in flap techniques

Limb reimplantation techniques using composite free-tissue transfer and microsurgical salvage of traumatized extremities have become standard reconstructive methods. Mechanisms for working with free-tissue transfers have advanced, specifically in regard to the use of thin-wire fixators: combining microsurgical techniques and thin-wire fixators helps in salvaging limbs that otherwise might be amputated. Also, combining the Ilizarov method with microsurgical techniques for limb salvage provides a new use for flaps. A further development in the use of flaps is the application of free-tissue transfers to preserve amputation levels in the war-injured. So-called fillet flaps serve as "spare parts" and can be customized for specific recipient sites. The so-called perforator flap makes use of feeder vessels, thus providing cutaneous and other composite flaps without sacrificing major vessels. Finally, the advent of the sural flap has made it possible to avoid microsurgical reconstruction but still provide adequate, well-vascularized cover, particularly in the distal third of the leg.

Dichloroacetate Reduces Tissue Necrosis in a Rat Transverse Rectus Abdominis Musculocutaneous Flap Model

OBJECTIVE

Ischemia-related complications may occur during postmastectomy transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction. The aim of our study was to investigate whether necrosis of susceptible flap regions could be reduced by dichloroacetate (DCA)-induced stimulation of oxidative metabolism in hypoxic tissue.

METHODS

The study was a randomized control trial using male Sprague-Dawley rats. A pedicled TRAM flap based upon the right inferior epigastric artery was elevated and reapproximated. Animals were randomly assigned to 1 of 5 treatment groups (n = 6). Group I received no DCA; groups II through V were administered 75 mg/kg DCA orally 24 hours preoperative; in addition, groups II through IV received 75 mg/kg/d DCA orally postoperative for 4 days; group III also received 75 mg/kg DCA (IP) intraoperatively; groups IV and V were given 15 mg/kg/d DCA orally for 6 days before the 24-hour preoperative treatment. Four days postsurgery, skin paddles were photographed and assessed for viability. Underlying TRAM muscle was biopsied for histologic analysis. Blood lactate levels were measured at pre- and postoperative time points. The mean percentages of viable skin paddle were as follows: 32.0%+/- 4.0% (group I), 68.1% +/- 6.2% (group II), 84.3% +/- 5.9% (group III), 92.8% +/- 2.0% (group IV), 82.6% +/- 5.8% (group V).

RESULTS

Statistically significant differences were found in all experimental (DCA) groups relative to the controls (P < 0.01). Group IV (6-day DCA preconditioning, plus 24-hour preoperative and 4-day postoperative treatment) displayed the greatest improvement in flap viability, significantly better than other DCA groups (P < 0.01). Group IV also had significantly lower serum lactate levels than controls (P < 0.05). Histologic examination of muscle biopsies revealed reductions in inflammation and necrosis correlating with DCA treatment and skin paddle survival.

CONCLUSIONS

This study indicates that DCA may provide a useful pharmacologic tool for reducing ischemia-related necrosis in TRAM flaps.

TRAM flap delay: an extraperitoneal laparoscopic technique

Although the transverse rectus abdominis musculocutaneous (TRAM) flap is the gold standard in autogenous breast reconstruction, it is less reliable in patients at high risk of ischaemic compromise. A preliminary delay procedure involving ligation of the deep inferior epigastric vessels has been shown to augment flap vascularity and improve outcome in those high risk patients undergoing unipedicled TRAM flap reconstruction. Despite previous description of a transperitoneal laparoscopic technique, surgical delay generally continues to be performed as an open procedure. This may reflect apprehension over the transperitoneal approach with its attendant risk of injury to intra-abdominal organs and vessels as well as adhesion formation. In this paper we describe an extraperitoneal laparoscopic technique for TRAM flap delay. Access to the deep inferior epigastric vessels is obtained using an extraperitoneal approach similar to that used for total extraperitoneal laparoscopic inguinal hernia repair and the vessels are easily identified and ligated using a single working port. While further study is required to evaluate the safety and efficacy of this technique, we report this as an alternative to the known open procedure which may be particularly useful for bilateral TRAM flap delay with the potential for reduced operative time, postoperative pain and scarring by avoiding bilateral inguinal incisions.

Is it Possible to Increase the Survival of the Transverse Rectus Abdominis Musculocutaneous Flap following previous Abdominoplasty Using a Delay Procedure? An Experimental Study in the Rat

BACKGROUND

Although, because of the disruption of perforators, abdominoplasty has been suggested as a major contraindication for patients undergoing autologous breast reconstruction with the transverse rectus abdominis musculocutaneous (TRAM) flap, many researchers encourage the search for a means of improving the survival of the skin paddle of the flap in patients who have undergone previous abdominoplasty. In this study, the effect of the surgical delay phenomenon on the survival of the TRAM flap following abdominoplasty was investigated.

METHODS

Thirty adult Wistar rats were used: the control group (n = 6), the short-term group (n = 12), and the long-term group (n = 12). In the control group, a standard superior pedicled TRAM flap was harvested with no abdominoplasty procedure, and the flap was replaced in situ. In all other animals, an abdominoplasty procedure was performed initially. The short-term and long-term groups were divided into two subgroups: the abdominoplasty plus TRAM-only subgroup (n = 6), and the abdominoplasty plus delay plus TRAM subgroup (n = 6). In the short-term group, the experiment was performed 1 month after abdominoplasty, whereas the same surgical procedures were applied 6 months after abdominoplasty in the long-term group.

RESULTS

The short-term abdominoplasty plus TRAM subgroup, the long-term abdominoplasty plus TRAM subgroup, the short-term abdominoplasty plus delay plus TRAM subgroup, the long-term abdominoplasty plus delay plus TRAM subgroup, and the conventional superior pedicled TRAM flap group showed 2.33 +/- 3.01 percent, 13.33 +/- 8.76 percent, 24.17 +/- 13.57 percent, 60 +/- 8.94 percent, and 70.83 +/- 9.70 percent survival rates for the skin paddle, respectively.

CONCLUSION

The data demonstrate that surgical delay after long-term abdominoplasty can enhance the survival rate of the skin paddle of the TRAM flap.

Sural Flap Delay Procedure

Over the last decade, the sural flap has been popularized as a suitable alternative to free-tissue transfer for soft-tissue coverage of the lower extremity. However, flap failure rates may be increased especially if patients have certain risk factors, such as age over 40 years, peripheral artery disease, venous insufficiency, diabetes mellitus, and others. This article describes a sural flap delay procedure to avoid flap necrosis in this potentially "high-risk" patient population.

Remote ischemic preconditioning of flaps: A review

Ischemic preconditioning (IP) is defined as a brief period of ischemia ("preclamping") followed by tissue reperfusion, thereby increasing ischemic tolerance for a subsequent longer ischemic period. Several studies showed the effectiveness of classic local IP by preclamping the flap pedicle. There are two temporally and mechanically different types of IP: acute preconditioning, which is induced by preclamping the flap pedicle briefly before flap ischemia, and late preconditioning, induced by a preclamping procedure 24-48 h before flap ischemia. However, both types of local ischemic preconditioning are rarely used clinically, most likely since they can be applied only by invasive means, significantly increase operation time, or even require a second surgical procedure. Several studies from our laboratory showed, in different experimental models, that acute IP, enhancement of flap survival, and improvement of reperfusion microcirculation can be achieved not only by preclamping the flap pedicle, but also by induction of an ischemia/reperfusion event in a body area distant from the flap prior to elevation. This new acute remote IP procedure can be applied without invasive means, using limb tourniquet ischemia briefly before flap ischemia. The effectiveness of acute remote IP was confirmed by other authors in large animal models. Another of our studies showed that late remote IP using a limb tourniquet 24 h before flap ischemia attenuates ischemia/reperfusion in muscle flaps, whereas it was ineffective in adipocutaneous flaps. The exact mechanism of "classic" as well as remote IP is not yet finally determined, although several studies demonstrated that endogenous nitric oxide plays an important role. In summary, the use of a tourniquet to induce limb ischemia before flap ischemia could provide a new, alternative, noninvasive remote IP protocol, although late remote IP might be effective only in muscle flaps. However, the possible future clinical application for late IP is elective flap surgery, whereas acute remote IP could even be used in emergency flaps.

Basic Fibroblast Growth Factor Expression following Surgical Delay of Rat Transverse Rectus Abdominis Myocutaneous Flaps

Partial transverse rectus abdominis myocutaneous (TRAM) flap loss in breast reconstruction can be a devastating complication for both patient and surgeon. Surgical delay of the TRAM flap has been shown to improve flap viability and has been advocated in "high-risk" patients seeking autogenous breast reconstruction. Despite extensive clinical evidence of the effectiveness of surgical delay of TRAM flaps, the mechanisms by which the delay phenomenon occurs remain poorly understood. To examine whether angiogenic growth factors such as basic fibroblast growth factor (bFGF) may play a role in the delay phenomenon, the authors studied the expression of bFGF in rat TRAM flaps subjected to surgical delay. Thirty-five female Sprague-Dawley rats were randomly assigned to one of four TRAM flap groups: no delay (n = 6), 7-day delay (n = 12), 14-day delay (n = 10), or 21-day delay (n = 7). Surgical delay consisted of incising skin around the perimeter of the planned 2.5 x 5.0-cm TRAM flap followed by ablation of both superior epigastric arteries and the left inferior epigastric artery, thus preserving the right inferior epigastric artery (the nondominant blood supply to the rectus abdominis muscle of the rat). TRAM flaps were then elevated after 7, 14, and 21 days of delay by raising zones II, III, and IV off the abdominal wall fascia. Once hemostasis was assured, the flaps were sutured back in place. All flaps were designed with the upper border of the flap 1 cm below the xiphoid tip. Three days after the TRAM procedure, postfluorescein planimetry was used to determine percent area viability of both superficial and deep portions of TRAM flaps. All rats were euthanized and full-thickness TRAM specimens were taken from zones I, II, III, and IV for enzyme-linked immunoabsorbent assay analysis of bFGF levels. Statistical testing was done by t test (percent viability) and two-way analysis of variance (bFGF levels). All delayed flaps had significantly higher bFGF levels when compared with all nondelayed control flaps (p < 0.05). The bFGF levels were not different in the rats that received TRAM flaps 7, 14, or 21 days after delay surgery. There was also no significant difference in bFGF levels among zones I through IV. Control rats had more peripheral zone necrosis compared with all delayed TRAM rats. All delayed flaps had a significantly higher area of flap viability superficially than nondelayed control flaps (p < 0.05). There was no difference in deep flap viability. Surgical delay of rat TRAM flaps is associated with improved flap viability and significantly elevated levels of bFGF over nondelayed TRAM flaps at postoperative day 3 after TRAM surgery. The increases in bFGF noted at this time point suggests that bFGF may play a role in the improved TRAM flap viability observed after delay surgery. Further investigation is needed to evaluate the role bFGF may play in the delay phenomenon.

A Vertical Midline Scar Is a ‘High-Risk’ Factor for Maximum Survival of the Rat TRAM Flap

The presence of any abdominal scar, in addition to obesity, a smoking history, and prior irradiation are considered the major known "risk factors" for predictable success or failure of the lower transverse rectus abdominis musculocutaneous (TRAM) flap. For many, a vertical midline scar has even been considered to be a relative contraindication. The possibility that the scar instead could effect some form of delay or by neovascularization permit reperfusion across the midline might negate this concern. The validity of this hypothesis was tested in 40 Sprague-Dawley (CD) rats using our standard rat TRAM flap model. Every rat initially had a vertical skin incision made from xiphoid to pubis. At a second stage, either immediately or after a delay of 1 week, 2 weeks, or 6 months, a superior-pedicled (dominant) or inferior-pedicled (nondominant) TRAM flap was raised, with five rats in each subgroup. For the inferior-pedicled group, the percentage of ipsilateral (muscle-pedicle half) flap survival approached 75% and had a trend toward greater survival with each increase in the time of delay, but any difference was not statistically significant (F= 0.653, P = 0.538). In the superior-pedicled group, the ipsilateral half of the flap always survived completely. In both groups, the contralateral or opposite side always underwent complete necrosis regardless of pedicle orientation or time constraints. The midline scar did not enhance even unilateral TRAM flap survival when compared with historic controls, and long-term transmidline reperfusion across the scar did not seem to occur. These findings corroborate the clinical observation that only a unilateral TRAM flap would be reliable in the presence of a vertical midline abdominal scar.

Effects of the abdominal midline incision on the survival of the transverse rectus abdominis musculocutaneous flap in rat model

The transverse rectus abdominis musculocutaneous (TRAM) flap, as the standard for breast reconstruction, can be performed in selected patients with operation scars in the abdomen. It is questioned why the unilateral TRAM flaps raised from the abdomen with scars seem to have more blood supply to the periphery. The effect of the abdominal midline incision on the survival of the TRAM flap was studied with the rat model. The survival of the inferiorly based unilateral TRAM flap was compared between a control group and three experimental groups in which initial abdominal midline incision was made 1, 2, or 4 weeks before TRAM flap elevation. The control group had a mean survival of 47.05 +/- 4.52% of their original flap surface area. The viabilities of the other groups were 72.19 +/- 11.05, 76.96 +/- 7.79, 90.26 +/- 3.67%, respectively. Results from all three groups were significantly higher than that of the control group. In the microangiogram of the TRAM flap, the main pedicle (deep epigastric system) and muscle perforators remained unchanged, but the subdermal plexus of the abdominal wall showed increase of size and density after incision. Histological examination also revealed corresponding findings. A midline incision in the abdomen, which was made at 1 or more weeks before unilateral TRAM flap formation, was found to improve the survival of the flap. These data may be explained by increase in the size and density of the subdermal plexus, which delivers the blood flow from the muscle perforators to the expanded area of abdominal wall. Therefore, the process of making the abdominal midline incision can be regarded as a minimal form of a prefabrication procedure, which is one of the well-known delay procedures.

Transverse rectus abdominis musculocutaneous flap (TRAM flap) - experimental model in rats

The objective of this paper was to report the use of an experimental model of the Transverse Rectus Abdominis Musculocutaneous flap (TRAM flap), in rats. Thirty male Wistar rats weighing 180 to 220 g were submitted to the TRAM flap procedure. This article reports on the use of the caudally based, right unipedicled TRAM flap.

Delay in unipedicled TRAM flap reconstruction of the breast: a review of 76 consecutive cases

Since its introduction in 1982, the transverse rectus abdominis musculocutaneous (TRAM) flap has become the standard therapy in autogenous breast reconstruction. A lower rate of partial flap (fat) necrosis is associated with microvascular free-flap transfer compared with the conventional (unipedicled) TRAM flap because of its potentially improved blood supply. A TRAM flap delay before flap transfer has been advocated, especially in a high-risk patient population (obesity, history of cigarette smoking, radiation therapy, or abdominal scar). The authors reviewed a series of 76 consecutive delayed unipedicled TRAM flap breast reconstructions during a 5-year period. Data were analyzed with respect to type of procedure and time of delay, overall outcome, general surgical complications, flap-related (specific) complications (partial or complete flap loss), and patient satisfaction. Seventy-six unilateral breast reconstructions using the unipedicled TRAM flap were performed between 1995 and 2000 in 76 patients (mean age, 47.4 years). Fifty-four flaps were performed as immediate reconstructions, and 22 as secondary procedures. Seventy-two flaps were based on the contralateral pedicle, and four flaps were based on an ipsilateral pedicle. In all cases, a flap delay consisted of ligature of both deep inferior epigastric arteries and veins, accessed from an inferior flap incision down to the fascia, with a mean of 13.9 days before the flap transfer. No acute flap take-back procedure had to be performed. There was no complete flap loss, and breast reconstruction was achieved in all cases. In five cases (6.6 percent), a partial (fat) flap necrosis occurred. Interestingly, the majority of these cases (four of five) were secondary breast reconstructions. In addition, of the five patients who had partial flap necrosis, four had a history of smoking, two received radiation therapy, three received chemotherapy, and three patients were obese (body mass index greater than or equal to 30) or overweight (body mass index greater than or equal to 25). In three cases, an early surgical complication (two wound infections at the flap interface and one at the donor site) occurred. One patient developed a deep vein thrombosis. Five patients developed secondary ventral hernias necessitating repair (6.6 percent). Forty-one patients underwent secondary nipple-areola reconstruction. In 19 patients of this group, a secondary procedure (e.g., scar revision, limited liposuction, and/or excision of contour deformities) was simultaneously performed. A survey of patient satisfaction was performed using a modified SF-36 questionnaire. Fifty-one patients participated (67 percent). The overall satisfaction was very high and 51 patients reported that they would recommend the procedure to others (100 percent). Multiple factors such as patient selection, surgical expertise, and preoperative and postoperative management contribute to the success of any type of autogenous breast reconstruction. However, rare partial and absent complete flap necrosis in the authors' series may be attributable to the flap delay. A low morbidity rate and short hospital stay may become increasingly relevant, with limited structural and financial resources in the future. Therefore, the delayed unipedicled TRAM flap should be regarded as a valuable option in attempted breast reconstruction using autogenous tissue in both a high-risk and the general patient population.

Reducing the vascular delay period in latissimus dorsi muscle flaps for use in cardiomyoplasty

Although the mechanism by which vascular delay benefits skin flaps is not completely understood, this topic has been extensively studied and reported on in the literature. In contrast, little has been documented about the effects of vascular delay in skeletal muscle flaps. Recent animal studies tested the effectiveness of vascular delay to enhance latissimus dorsi muscle flap viability for use in cardiomyoplasty and found that it prevented distal flap necrosis. However, these studies did not define the optimal time period necessary to achieve this beneficial effect. The purpose of this study was to determine how many days of "delay" can elicit the beneficial effects of vascular delay on latissimus dorsi muscle flaps. To accomplish this, 90 latissimus dorsi muscles of 45 male Sprague-Dawley rats were randomly subjected to vascular delay on one side or a sham procedure on the other. After predetermined delay periods (0, 3, 7, 10, and 14 days) or a sham procedure, all latissimus dorsi muscles were elevated as single pedicled flaps based only on their thoracodorsal neurovascular pedicle. Latissimus dorsi muscle perfusion was measured using a Laser Doppler Perfusion Imager just before and immediately after flap elevation. The muscles were then returned to their original vascular beds, isolated from adjacent tissue with Silastic film, sutured into place to maintain their original size and shape, and left there for 5 days. After 5 days, the latissimus dorsi muscle flaps were dissected free, scanned again (Laser Doppler Perfusion Imager-perfusion measurements), and the area of distal necrosis was measured using digitized planimetry of magnified images. The authors' results showed that delay periods of 3, 7, 10, and 14 days significantly increased (p < 0.05) blood perfusion and decreased (p < 0.05) distal flap necrosis when compared with sham controls. On the basis of these findings, the authors conclude that in their rat latissimus dorsi muscle flap model the beneficial effects of vascular delay are present as early as 3 days. If these findings also hold true in humans, they could be useful in cardiomyoplasty by allowing surgeons to shorten the amount of time between the vascular delay procedure and the cardiomyoplasty procedure in these very sick patients.

The relative importance of the deep and superficial vascular systems for delay of the transverse rectus abdominis musculocutaneous flap as demonstrated in a rat model

The use of some form of delay maneuver for "high-risk" patients before transfer of the superior pedicled lower transverse rectus abdominis musculocutaneous (TRAM) flap for breast reconstruction has augmented the rate of success in both the experimental and clinical arenas. A common method of vascular delay has been the bilateral division of both the superficial inferior epigastric and deep inferior epigastric vessels. Whether all of these must be divided to adequately effect the delay is unknown. For that matter, the relative importance of the superficial versus the deep vascular systems is unclear. To investigate this uncertainty, a delay was attempted in 61 Sprague-Dawley rats by division of either the superficial inferior epigastric or deep cranial epigastric vessels (the latter is the homologue to the human deep inferior epigastric) in unilateral or bilateral fashion. Division of the contralateral superficial inferior epigastric vessel resulted in significantly greater TRAM flap survival than either ipsilateral or bilateral superficial inferior epigastric vessel division (p = 0.0034 or p = 0.0093, respectively). Division of the ipsilateral or bilateral deep cranial epigastric vessel resulted in significantly greater flap survival than just contralateral deep cranial epigastric vessel division (p = 0.0034 or p = 0.006, respectively). No significant difference was observed between the group having contralateral superficial inferior epigastric or groups with ipsilateral deep cranial epigastric division, implying that either alone would be efficacious to achieve the desired delay effect. This would allow the other vascular system to be retained intact for later potential salvage maneuvers as needed.

Comparison of a new method for computer analysis with standard techniques for measuring survival rates in the rat transverse rectus abdominis musculocutaneous flap

Many methods have been used to measure experimental flap survival in animal models. These have previously included planimetry, computer programs, and (routinely by the authors) the simple measurement of the weight of a template traced according to the dimensions of a given flap. To test the validity of their method, an alternative technique was developed by the authors' biostatiticians. Initially, in a study of rat transverse rectus abdominis musculocutaneous (TRAM) flaps, all templates were also scanned electronically to form bitmaps. Using commonly available software programs, each bitmap was colorized corresponding to viable and nonviable areas of the flaps. A summation of individual pixels by color could then be used to calculate the percentage of flap survival. A comparison of both methodologies in 64 rat TRAM flaps found that the survival rate was slightly greater overall when a computer analysis had been performed (3.1 +/- 1.7%), but this was not a significant difference (p = 0.479). Thus, the previous standard method was proven reliable, but just as precise calculations are now possible using the convenience of any personal computer.

Single-stage, autologous breast restoration

The skin-sparing mastectomy, when performed with immediate reconstruction, is a major advance in breast reconstruction. Traditionally, reconstruction of the nipple-areola complex is performed as a subsequent procedure. In this study, 17 patients (mean age, 43 years; range, 35 to 53 years) underwent one-stage breast and nipple-areola reconstruction over a 21-month period. In all cases of breast reconstruction, a buried transverse rectus abdominis musculocutaneous (TRAM) flap was used, and all patients had a simultaneous nipple-areola complex reconstruction performed. Nine patients had a Wise keyhole pattern used and contralateral reduction performed. Four patients retained all their breast skin, and a TRAM skin island was used in another four. It has recently been shown that patients with early-stage breast cancer and peripherally sited tumors have a very low risk of nipple-areola involvement. In 10 patients with early disease and peripheral tumors, the areola was retained (as a thin full-thickness graft), but more recently, in three patients with early-stage disease, the entire nipple-areola complex was used as a thin full-thickness graft. The thin full-thickness skin graft is removed from the breast in an apple-coring fashion, so that most of the ducts are retained as part of the mastectomy specimen. (There was histological confirmation of absence of tumor in the nipples of these patients.)One-stage autologous reconstruction should be considered for all patients undergoing immediate breast reconstruction. In patients with early-stage disease and peripheral tumors, the nipple-areola complex may be retained through the use of a thin full-thickness graft that is applied to a deepithelialized CV flap on the TRAM flap. This allows the best method of nipple-areola complex reconstruction: by retaining the original breast envelope, the color match and texture in the reconstruction are ideal. Patient satisfaction in this study was high. Necrosis of the mastectomy flaps impaired the cosmetic results in some patients. A large multicenter study is required to confirm the effectiveness of this procedure.

Delaying the skin for TRAM flaps

This study was undertaken to determine whether a less extensive delay procedure would be as efficacious as the standard delay procedure in breast reconstruction.Between July 1996 and February 1999, 15 patients underwent delay procedures prior to breast reconstruction. Six patients underwent the standard delay procedure. Nine patients underwent a less extensive skin delay procedure. Transverse rectus abdominis myocutaneous (TRAM) reconstruction was performed 1 week after delay procedures.Average operating time was 28.7 minutes for the standard delay and 19.7 minutes for the skin paddle delay. The incidences of fat necrosis were 17% in the standard delay group and 22% in the skin paddle delay group. The incidences of partial flap loss/slow healing were 17% in the standard delay group and 22% in the skin paddle delay group. The incidence of complications in each group was the same: approximately 1 per patient.Operating times were not statistically different between the two groups (p = 0.06). There was no increase in the incidence of slow healing/partial flap loss or fat necrosis in the skin delay group. The skin delay procedure for TRAM flaps seems to provide a concise delay procedure that does not increase the incidence of complications in those high-risk patients.

Ischemic preconditioning improves the survival of skin and myocutaneous flaps in a rat model

Inadequate blood supply of pedicle flaps results in partial necrosis, and prolonged ischemia during free-tissue transfer can result in partial or complete flap necrosis. Recent research in the field of cardiovascular surgery has shown that ischemic preconditioning (repeated brief episodes of coronary artery occlusion followed by reperfusion) improves myocardial muscle survival when the heart is subsequently subjected to prolonged ischemia. Preconditioning of skin or myocutaneous flaps as either pedicle or free flap models has never been studied. The goal of this investigation was to measure the effect of ischemic preconditioning on myocutaneous and skin flap survival areas and total necrosis rates after variable periods of global ischemia. In 220 rats, 100 transverse rectus abdominis myocutaneous flaps and 120 dorsal cutaneous flaps were randomized into treatment and control groups. The treatment flaps underwent preconditioning by three cycles of 10 minutes of pedicle clamping followed by 10 minutes of reperfusion for a total preconditioning period of 1 hour. The control flaps were perfused without clamping for 1 hour. Both control and treatment flaps then underwent global ischemia for 0, 2, 4, 6, 10, or 14 hours by pedicle clamping. Flap survival area was measured on the fifth postoperative day. Statistical analysis was performed with analysis of variance, student's t tests, and probit analysis. Preconditioning improved survival areas of pedicle myocutaneous flaps (0-hour group) from 47 +/- 16 percent (mean percent area surviving +/- SD) to 63 +/- 5 percent. This difference was statistically significant (t test, p < 0.04). There was no statistically significant improvement in pedicle skin flap survival. For free flap models (flaps undergoing global ischemia), preconditioning increased the survival areas of skin and myocutaneous flaps (analysis of variance, p < 10(-5)). For the skin flap model, statistical significance of the survival area difference was reached at 6, 10, and 14 hours of ischemia (t test, p < 10(-4)). The magnitude of this effect was higher in the myocutaneous flap model and reached statistical significance at 2, 4, 6, and 10 hours of ischemia (p < 10(-3)). Preconditioned flap survival areas were increased by two to five times that of non-preconditioned flaps at these ischemia times. Preconditioning lowered total necrosis rates at all ischemia times for both flap models. The critical ischemia time when 50 percent of skin flaps became totally necrotic (CIT50) improved from 6.9 to 12.4 hours by preconditioning. Similarly, preconditioning improved the CIT50 of myocutaneous flaps from 3.6 to 9.2 hours. For the first time, statistically significant improvements of partial necrosis areas and total necrosis rates have been demonstrated through intraoperative ischemic preconditioning of skin and myocutaneous flaps. In clinical practice, application of this technique may lead to improved survival during pedicled or free transfer of myocutaneous flaps and free transfer of skin flaps.

TRAM flap perforator ligation and the delay phenomenon: development of an endoscopic/laparoscopic delay procedure

Despite its versatility in breast reconstruction, the TRAM flap is at times subject to ischemic compromise, especially in certain high risk populations. A preoperative delay procedure can decrease the likelihood of TRAM flap failure or fat necrosis, but the required extent of this delay procedure is not clearly defined. In an attempt to augment flap vascularity while reducing surgical dissection and morbidity, six distinct delay procedures and a nondelayed control were compared in a rat TRAM flap model (n = 8 for all groups). An important feature that was incorporated into several groups was the ligation of the contralateral rectus perforators through minimal skin incisions (endoscopic analogy, groups 4 to 7). The most effective delay procedure was the combination of contralateral rectus perforator ligation and ipsilateral dominant pedicle ligation (group 7), which was achieved with two minimal skin incisions and no significant flap undermining. This procedure reduced the flap necrosis from 63.2 +/- 5.8 percent (control) to 13.5 +/- 3.3 percent (p < 0.001). After completion of the animal studies, clinical application of a "minimally invasive" TRAM flap delay procedure was then undertaken in eight high risk patients with only modest ischemic compromise. Although the clinical experience is too early to draw definite conclusions, we feel that "endoscopic delay" has potential as a modality that will increase flap vascularity but minimize the morbidity of the preliminary procedure.