Deep Inferior Epigastric Artery Perforator Research Articles

Safety of Combined Deep Inferior Epigastric Artery Perforator Flaps and Gynecologic Procedures

Safety of Combined Deep Inferior Epigastric Artery Perforator Flaps and Gynecologic Procedures

Patient-Reported Abdominal Morbidity Following Abdomen-Based Breast Reconstruction.

Abdominal wall morbidity occurs with increased frequency following flap harvest in the obese abdomen. Its impact on patient-reported outcomes (PROs) in breast reconstruction has been poorly characterized. A retrospective review of obese patients undergoing abdominal-based free autologous breast reconstruction was conducted over 15 years. Patient operative characteristics were recorded and outcomes were analyzed. PROs were assessed using the BREAST-Q abdominal survey. In total, 75 women (108 flaps) with the mean body mass index (BMI) of 33.2 were included. Flaps included deep inferior epigastric artery perforator (24%), muscle-sparing (43%), and free transverse rectus abdominis myocutaneous flaps (f-TRAM; 33%). World Health Organization (WHO) obesity class, BMI, and flap type did not affect flap failure (1%) or complication rates. Hernia developed in 7%; all necessitated repair. Eight percent developed abdominal bulge; one was repaired. Hernia formation was associated with increased patient age (p < 0.05). Bulge formation occurred more often in f-TRAM donor sites (p = 0.005). BMI, WHO class, flap type, and mesh use were not related to hernia or bulge occurrence in either univariate or multivariate analysis. The survey response rate was 63%. Abdominal Physical Well-Being (proxy for abdominal wall function) and Satisfaction with Abdomen (patient-perceived cosmesis) were similar across flap types, age, and WHO classification groups. Patients with postoperative bulge reported higher abdominal physical well-being scores, regardless of flap type (p < 0.01). Bulge was correlated with lower satisfaction (p < 0.05). The incidence of abdominal wall morbidity following abdominal free-tissue transfer for breast reconstruction was acceptably low in our population of obese patients. Hernia was a clinically significant complication, warranting surgical repair. Bulge was primarily a cosmetic concern and did not detract from patient-reported abdominal wall function. Age may represent an independent risk factor for hernia formation in this population.

Pedicle stabilization with fibrin sealant in DIEP flap breast reconstruction.

Microsurgical procedures are nowadays routinely performed worldwide in reconstructive surgery. The deep inferior epigastric artery perforator (DIEP) flap has become the gold standard in breast reconstruction due to its excellent outcomes and lower donor site morbidity. However, complications, including flap failure, still occur in DIEP flap breast reconstruction. Often, according to our experience, these complications result from pedicle disorders, which can be attributed to postoperative mobilization. In the present study, we evaluated the efficacy and safety of using a fibrin sealant as a method for pedicle stabilization to prevent pedicle mobilization in the postoperative period. With our technique, after the flap insetting and microsurgical anastomosis, the pedicle was stabilized by applying a fibrin sealant (TISSEEL™) around and over the entire pedicle. Our study included a homogeneous series of 70 patients who received a delayed DIEP flap breast reconstruction. A retrospective study was conducted to evaluate this novel technique compared to the conventional method. In our experience, the fibrin glue allowed us to reduce the strain for correct pedicle positioning and all subsequent efforts to avoid displacements in the postoperative period. Our preliminary results suggest that this method may lead to a reduction in overall complications attributable to pedicle disorders.

The Full Continuum of Robotic Breast Surgery: Robotic-assisted Mastectomy, Robotic DIEP Flap, and Robotic Supermicrosurgery

Summary: In recent years, robotic surgery has rapidly expanded to improve surgical outcomes in a variety of surgical subspecialties. Although plastic surgery has taken longer to integrate robotic surgery into practice, the advantages of robotic-assisted surgery, including improved visualization and resolution, minimally invasive approaches, and the ability to surpass human precision and scale, have driven its more recent adoption into plastic surgery. Currently, procedures performed with robotic assistance that are considered part of the continuum of surgical treatment of breast cancer include robotic-assisted nipple-sparing mastectomy, reconstruction with the robotic latissimus dorsi flap or the deep inferior epigastric artery perforator flap, and robotic microsurgery for the flap anastomosis and/or the surgical treatment of lymphedema. The authors provide an overview of robotic surgery and how it has been integrated into the field of plastic surgery, as well as a review of the most common procedures within the field where robotic assistance can be incorporated: nipple-sparing mastectomy, robotic latissimus flap, robotic deep inferior epigastric artery perforator flap breast reconstruction, and microvascular anastomoses.

DIEP Flap for Head and Neck Reconstruction: An Underutilized Option!

Background The deep inferior epigastric artery perforator (DIEP) flap is a workhorse flap for breast reconstruction. Its use for head and neck (HN) reconstruction is rare. Abdomen provides a donor site abundant in skin and subcutaneous tissue, amenable to primary closure; sizeable, robust, and consistent perforators and a long, sizeable pedicle for comfortable microvascular anastomosis. Its offers all the donor variables needed for HN reconstruction in abundance. Methods It is a quasiexperimental design study. DIEP flap use for HN reconstruction in our series was opportunistic, that is, when donor site matched the defect. Cases that had very thick thighs and lesser bulk in abdomen and cases that had very thin thighs but much more bulk in abdomen were considered for reconstruction using DIEP flap. Results The DIEP flap was done in 11 cases for HN reconstruction. There were two re-explorations during postoperative period: one flap loss and another had partial necrosis. Conclusion Abdomen is an excellent donor site option for HN reconstruction in selected cases, especially when harvested as a perforator flap.

Reconstruction of a septic femoral triangle fistula with a pedicled DIEP flap: A case report and mini-review

Flap-based reconstruction techniques have shown promise in preventing scar contractures and enhancing healing in fold areas by providing vascularized and thick tissue. We report a septic rupture of the superficial femoral artery treated with an arterial allograft and covered with a contralateral pedicled Deep Inferior Epigastric Artery Perforator (DIEP) flap. The patient presented favorable outcomes, including optimal healing at 8 months, with no functional limitation. A literature review also discusses alternative pedicled perforator flaps. These modern techniques present several advantages, including reliability, and can be of great interest in complex vascular surgery cases.

Bilateral Free Deep Inferior Epigastric Artery Perforator Flaps for Reconstruction following Mastectomy in Poland Syndrome Patients.

Poland syndrome is classically described as symbrachydactyly, with hypoplasia of the pectoralis major and other upper thoracic musculoskeletal structures. It is thought to be caused by intrauterine interruption in subclavian arterial flow and often includes breast hypoplasia. Affected vasculature can pose a challenge for reconstruction with free flaps because inflow may not be reliable in this patient population. We present the rare case of a 28-year-old woman with left-sided Poland syndrome, significant family history of breast cancer, and BRCA1+ mutation who underwent bilateral prophylactic nipple-sparing mastectomies with successful immediate bilateral deep inferior epigastric artery perforator free flap reconstruction. The surgical literature in this clinical scenario is also reviewed. Preoperative computed tomography angiography of the chest successfully demonstrated the patency and quantified the caliber of the internal mammary vessels to support free flap breast reconstruction. Free tissue transfer is a viable option for breast reconstruction in patients with Poland syndrome undergoing mastectomy guided by preoperative computed tomography angiography to characterize the internal mammary vasculature.

Bilateral Perineal Reconstruction Using an Oblique V-shaped DIEP Flap

The reconstruction of soft tissue defects in the peritoneal region after malignant tumor resection is challenging. To reconstruct large defects, primary closure or local flaps are inadequate, and they do not provide cosmetically and functionally good results. The gracilis, gluteal, and rectus abdominis flaps are workhorse flaps for reconstructing large peritoneal defects. Surgical procedures should be carefully chosen on the basis of the size and location of the defect. In this report, we describe two cases of bilateral large defect reconstruction after malignant tumor resection using a V-shaped deep inferior epigastric artery perforator flap. Our procedure is useful as it shows that single flaps can be used to reconstruct large and bilateral peritoneal defects.

Ultrasonographic assessment of rectus abdominis muscle adaptation after deep inferior epigastric artery perforator (DIEP) flap surgery: Single institution retrospective study.

The impact of deep inferior epigastric artery perforator (DIEP) flap on abdominal wall integrity has been the topic of an ongoing debate with previous studies having reported conflicting results using various imaging modalities. Ultrasonography is a noninvasive, cost-effective, and readily available method for evaluating the changes to the rectus muscle after DIEP flap surgery. In the present study, we aimed to compare rectus abdominis muscle thickness between the operated and non-operated sides using ultrasound imaging. The muscle thickness was measured at the cross point of the midclavicular line and the level of the umbilicus and anterior superior iliac spine using real-time B-mode ultrasonography. The muscle anteroposterior diameters of the pedicle-dissected side and the control side were compared using paired t test. In total 31 patients with a mean follow-up of 70.18 weeks were included. The mean diameters at the level of the umbilicus of the operated and non-operated sides were 8.16 ± 1.83 and 8.14 ± 1.43 mm, respectively (P = .94). The mean thicknesses at the anterior superior iliac spine level were 7.74 ± 1.85 on the flap harvested side and 8.04 ± 1.84 mm on the control side (P = .35). There was no statistically significant difference between the 2 groups. Ultrasonography can be a reliable, inexpensive, and easily usable modality for evaluating donor site complication following DIEP flap. DIEP flap seems to have minimal impact on the abdominal donor site, and it may be safe and versatile to reconstruct the breast after mastectomy.

Skin deformation analysis for pre-operative planning of DIEAP flap reconstruction surgery.

Deep inferior epigastric artery perforator (DIEAP) flap reconstruction surgeries can potentially benefit from augmented reality (AR) in the context of surgery planning and outcomes improvement. Although three-dimensional (3D) models help visualize and map the perforators, the anchorage of the models to the patient's body during surgery does not consider eventual skin deformation from the moment of computed tomography angiography (CTA) data acquisition until the position of the patient while in surgery. In this work, we compared the 3D deformation registration from supine arms down (CTA position) to supine with arms at 90° degrees (surgical position), estimating the patient's skin deformation. We processed the data sets of 20 volunteers with a 3D rigid registration tool and performed a descriptive statistical analysis and statistical inference. With 2.45mm of root mean square and 2.89mm of standard deviation, results include 30% cases of deformation above 3mm and 15% above 4mm. Pose transformation deformation indicates that 3D surface data from the CTA scan position differs from data acquired in loco at the surgical table. Such results indicate that research should be conducted to construct accurate 3D models using CTA data to display on the patient, while considering projection errors when using AR technology.

Transforming breast reconstruction: the pioneering role of artificial intelligence in preoperative planning.

Autologous breast reconstruction surgery is a vital part of the recovery process for patients with breast cancer. While various reconstructive options exist, the deep inferior epigastric artery perforator (DIEP) flap is often favoured for its ability to closely mimic natural breast tissue. However, the complex vascular anatomy associated with the deep inferior epigastric artery (DIEA) presents challenges for surgeons during DIEP flap execution. Preoperative imaging, such as computed tomography angiography (CTA), is commonly used to understand vascular architecture and aid in selecting appropriate perforators. Conventional reporting of CTA scans is a labour-intensive process that can be challenging and requires specific expertise. The integration of artificial intelligence (AI) and machine learning (ML) algorithms in medical imaging has the potential to address these challenges. AI can enhance CTA through improved data acquisition, image post-processing, and potentially interpretation. By automating the perforator selection process, AI applications can significantly reduce the time spent on preoperative imaging analysis and potentially improve accuracy and reliability. While AI shows promise in optimizing efficiency, accuracy, and reliability in breast reconstruction planning, challenges and ethical considerations need to be addressed. This article explores the challenges, opportunities, and future directions of using AI in the preoperative planning of autologous breast reconstruction.

Improving Visualization of Intramuscular Perforator Course: Augmented Reality Headsets for DIEP Flap Breast Reconstruction.

Augmented reality (AR) technology, exemplified by devices such as the Microsoft HoloLens 2, has gained interest for its potential applications in preoperative guidance. This study explores the use of AR technology for perforator identification during deep inferior epigastric artery perforator (DIEP) flap breast reconstruction. A case series of five patients where an AR device was used to identify perforators during DIEP flap breast reconstruction is presented. The device was utilized to recognize preoperative perforators and map their extra- and intramuscular routes. Sound and/or color Doppler confirmation was used to verify the findings. In all five cases, the AR device successfully identified preoperative perforators and delineated their extra- and intramuscular routes. AR technology in perioperative visualization of vasculature offers the potential to enhance surgical precision and reduce operative times. By providing an augmented three-dimensional overlay of patients' vascular structures, AR can facilitate a more comprehensive understanding of individual anatomy, ultimately improving surgical outcomes. AR technology shows promise in enhancing perforator identification efficiency and deepening understanding of perforator trajectories during preoperative planning. Nonetheless, additional research is needed to establish whether the advantages of AR technology warrant its widespread adoption for perforator identification.

Comparison of patient-reported achievements of goals and core outcomes with delayed breast reconstruction in irradiated patients: latissimus dorsi with an implant versus DIEP.

Different women's individual goals with a breast reconstruction vary, and few studies compare techniques in light of the different goals. This study aimed to compare patient-reported core outcomes in patients reconstructed with deep inferior epigastric artery perforator (DIEP) flaps and latissimus dorsi (LD) flaps. Second, breast-related factors that the patients were particularly satisfied/dissatisfied with were analyzed. This was a retrospective cross-sectional study, which includes women who had undergone mastectomy and radiation, followed by delayed breast reconstructions with either LD flap and implant or DIEP flap during 2007-2017. The patient-reported core outcomes of overall breast-specific quality of life, normality, women's cosmetic satisfaction, self-esteem, emotional well-being, and physical well-being were analyzed using BREAST-Q. The patients were divided into LD and implant (n = 135 patients) and DIEP (n = 118 patients) groups, and both were demographically similar. The median follow-up was 8 years. The DIEP group scored significantly higher than the LD and implant group in five out of six domains. A high satisfaction was reported in questions regarding the feeling or appearance when having clothes on, whereas the greatest dissatisfaction was reported regarding questions entailing symmetry and the appearance without clothes. After 7 years, patients' breast-specific quality of life, normality, women's cosmetic satisfaction, self-esteem, emotional well-being, and physical well-being seem to be higher in irradiated patients who have been reconstructed with DIEP flap as compared to patients reconstructed with LD flap and implant. In both groups, patient satisfaction is high regarding their appearance when clothed, whereas the lowest satisfaction scores were reported in situations without clothing.

Robot-assisted DIEAP flap harvesting: a review of techniques

Robotic surgery has expanded the capabilities of human surgical techniques by offering tremor elimination, ergonomic positioning, 3D viewing, and improved resolution.The purpose of the study: to examine DIEAP flap harvesting techniques using minimally invasive robot-assisted techniques.Material and Methods. The PubMed, SCOPUS, ScienceDirect, and Russian scientific electronic library databases were used for the review; the search was performed using the key phrases robotic deep inferior epigastric artery perforator flap, robotic DEIAP, robotic breast surgery, robot-assisted breast reconstruction. Inclusion criteria: case reports or cadaveric studies.Results. Nine studies were found that met the inclusion parameters. Nine studies looking at DIEAP flap extraction using robot-assisted techniques included a total of 59 patients. Five studies defined the flap harvesting technique as transperitoneal or intraperitoneal. Only 1 study described extroperitoneal flap harvesting. Three studies used the same terminology: transabdominal preperitoneal and total extroperitoneal. A lack of consensus in terminology was found.Conclusion. Robot-assisted DIEAP flap harvesting can be performed using transabdominally preperitoneal and total extraperitoneal techniques, as well as using monoport and multiport accesses with different port locations. However, for a more detailed study, randomized controlled trials with control of anterior abdominal wall weakness and with comparison of complications of different techniques are needed.

Superficial outside-flap shunt (SOS) is associated with a low incidence of postoperative DIEP flap venous congestion: A single-institution retrospective cross-sectional study

Venous congestion burdens up to 15% of deep inferior epigastric artery perforator (DIEP) flap breast reconstructions. For these cases, venous augmentation by superficial outside shunt (SOS) is associated with 100% success in secondary salvage surgeries. Intraoperative venous augmentation using other techniques yields a 0.3% rate of return to theater due to venous congestion, but there is no evidence assessing the effectiveness of the SOS technique applied preventively. Comparing this preventive approach to data prior to its implementation, we expect to find a reduced number of venous congested flaps with reduced flap losses and revision surgeries. This retrospective cross-sectional study involved DIEP flap breast reconstructions performed between 2011 and 2020. The control group included patients receiving additional venous anastomosis as a secondary salvage procedure. The "preventive SOS group" included patients who received preventive SOS during the main surgery. Age, body mass index (BMI), pregnancies, perioperative treatments (neoadjuvant or adjuvant chemo or radiotherapy), follow-up complications (arterial ischemia, venous congestion, hematomas, partial/total flap loss), and revision surgeries (breast debridement, flap remodeling) were recorded and compared. Within 695 flaps performed, 397 flaps were included in the control group, and 298 flaps were included in the preventive SOS group. The groups were homogeneous for age (p=0.418), BMI (p=0.747), and flap weight (p=0.064). Fifty-one flaps (12.8%) in the control group compared to zero (0.0%) in the preventive SOS group required return to theater (p<0.001). We reported encouraging preliminary results for SOS to prevent DIEP flap venous congestion. These results must be validated prospectively.

Serial Comparison of Patient-Reported Outcomes of Immediate Breast Reconstruction: Direct-to-Implant Versus Deep Inferior Epigastric Perforator Flap.

Direct-to-implant (DTI) and deep inferior epigastric artery perforator (DIEP) flaps are the two most common methods of immediate breast reconstruction. This study aimed to compare patient-reported outcomes between the two methods and to evaluate whether outcomes change over time. The data of patients who underwent immediate breast reconstruction using DTI or DIEP flaps between July 2017 and October 2021 were retrospectively reviewed. Patients who completed the BREAST-Q Reconstruction Module at 6months and > 12months after reconstruction were analyzed. Mann-Whitney and Wilcoxon signed-rank test were used to compare outcome between DTI and DIEP groups, and serial comparisons were performed. Of 375 patients included in the analysis, 146 patients completed questionnaires > 1year of follow-up (20.79 ± 8.55 months). The DTI and DIEP groups had 102 (69.9%) and 44 (30.1%) patients, respectively. There were no intergroup differences in the mean scores representing any of the domains at 6 postoperative months. After > 1year of follow-up, patients who underwent DIEP-flap reconstruction had greater satisfaction with their breast reconstructions (p < 0.001) and greater satisfaction with their overall outcomes (p < 0.001). In the DTI group, satisfaction scores did not change over time in any of the domains. In the DIEP group, however, the mean scores reflecting satisfaction with the breast (p = 0.001), overall outcome (p = 0.045), psychosocial well-being (p = 0.015), and sexual well-being (p = 0.042) significantly increased over long-term follow-up relative to the scores at 6 postoperative months. Patient-reported outcomes improved over time in association with DIEP reconstructions, reflecting higher satisfaction levels than those associated with DTI reconstruction. 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 .

Giant Pilomatrix Carcinoma of the Thorax: An Uncommon and Clinically Misdiagnosed Tumor

Summary: Pilomatrix carcinoma is an unusual and aggressive malignant tumor deriving from follicular matrix cells and exhibiting a metastatic potential to lungs and regional lymph nodes in 10% of cases. We report the case of a 54-year-old male patient who presented with a biopsy-proven malignant pilomatrixoma of the thoracic region, which recurred multiple times after previous excisions. Due to the size of the tumor (28 by 22 cm), wide excision and axillary lymphadenectomy of levels I and II were performed, followed by reconstruction with a free deep inferior epigastric artery perforator flap and adjuvant radiotherapy. Owing to its rarity, this tumor can initially be misdiagnosed, resulting in delayed treatment and recurrences if inadequately excised. Also, large tumor size is correlated with a higher incidence of metastasis. High index of clinical suspicion and wide excision are recommended, along with the need of establishing oncological guidelines for better prognosis.

Breast-Q sensory outcomes of non-neurotized, autologous, unilateral breast reconstruction with a minimum of 3-year follow-up

Sensory reinnervation of autologous breast tissue after free flap reconstruction is highly variable. There is no long-term follow-up data exploring spontaneous reinnervation and how this affects patients' quality of life nor the nerve-related symptoms they experience. To address this issue, we invited patients with a minimum of 3 years after non-neurotized, free flap breast reconstruction to complete patient-reported outcome measures exploring sensation, quality of life and breast-related symptoms. We performed a retrospective cohort study of patients undergoing unilateral Muscle-Sparing Transverse Rectus Abdominus Muscle (MS-TRAM) or deep inferior epigastric artery perforator (DIEP) flap breast reconstruction between 01-01-2015 and 31-12-2019 in the Department of Plastic and Reconstructive Surgery at Manchester University NHS Foundation Trust. We invited participants to complete the recently developed Breast-Q© Breast Sensation Module. All patients had undergone unilateral immediate (n= 85) or delayed (n= 82) breast reconstruction after mastectomy using either a free DIEP (n= 150) or TRAM (n= 17) flap reconstruction a minimum of 3 years prior. The median age at operation was 48. Sensation after reconstruction was significantly reduced in the reconstructed breast compared with the contralateral breast (P<0.0001) with a reduction in reported quality of life (immediate (68.0 [54.0, 89.0]) and delayed (68.0 [62.0, 83.8])). The sensation was significantly better in immediate vs delayed procedures (P=0.024). Sensory scores after reconstruction increased with age (P=0.036). Breast sensation after non-neurotized reconstruction with autologous tissue is significantly reduced at long-term follow-up with a reduction in quality of life. A minimum outcome set for quantification of breast sensation is required and future research into the cost-benefit of neurotized, autologous breast reconstruction is needed.

The Delay Procedure in Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction.

The delay procedure in deep inferior epigastric artery perforator (DIEP) flap breast reconstruction, in which the reduced-caliber choke vessels play a major role, can provide more well-perfused tissue than a standard DIEP flap. The aim of this study was to review the authors' experience with this technique, evaluate the indications, and analyze the surgical outcomes. A retrospective study was conducted of all consecutive DIEP delay procedures performed between March of 2019 and June of 2021. Patient demographic characteristics, operative details, and complications were registered. Patients had preoperative imaging by magnetic resonance angiography to select dominant perforators. The surgical technique involves a two-stage operation. During the first operation, the flaps were pedicled on a dominant perforator and a lateral skin bridge extending toward the lateral flank and lumbar fat; in a second stage, the flap was harvested and transferred. A total of 82 extended DIEP delay procedures were performed to reconstruct 154 breasts. The majority were bilateral breast reconstructions (87.8%). The delay procedure was used for 38 primary reconstructions (46.3%) and 32 tertiary reconstructions (39.0%). The primary indication was the need for additional volume (79.3%), followed by extensive abdominal scarring and liposuction. After the first operation, seroma was the most frequently observed complication (7.3%). After the second operation, three total flap losses (1.9%) were observed. The delay procedure in DIEP flap breast reconstruction results in the harvest of a good amount of abdominal tissue by adding a preliminary procedure. This technique can convert cases previously considered unsuitable into suitable candidates for abdominal-based breast reconstruction. Therapeutic, IV.

Efficacy of superficial inferior epigastric vein superdrainage in free TRAM and DIEP flap: An indocyanine green angiography study of 68 cases

This study aimed to evaluate the clinical efficacy of venous augmentation using superficial inferior epigastric vein (SIEV) in free transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery perforator (DIEP) flap and investigate the factors that hinder the venous superdrainage. A retrospective review of 62 free muscle-sparing (MS)-TRAM and 6 DIEP unilateral breast reconstructions from September 2017 to July 2022. Intraoperative indocyanine green angiography was performed on the harvested flap, with the SIEV contralateral to the pedicle side clamped and unclamped for 20min. The relative ratio of hypoperfused area to the total flap area was calculated and compared quantitatively. The preoperative computed tomography (CT) angiography was reviewed to obtain information on the SIEV diameter and number of midline-crossing medial branches. The participants were categorized into three groups: 42 patients in Group 1 (>3% decrease in hypoperfused area), 20 patients in Group 2 (change in hypoperfused area ranging from -3% to 3%), and six patients in Group 3 (>3% increase in hypoperfused area). The mean number of midline-crossing branches (p=0.002) and mean difference in the diameter of bilateral SIEVs (p=0.039) were significantly greater in Group 1 than in the other groups. Thirty-eight percent (26/68 cases) resulted in sustained or aggravated perfusion after SIEV superdrainage. Superdrainage using the contralateral SIEV in free MS-TRAM/DIEP flap is recommended when there are more than two midline-crossing medial branches of SIEV and when the caliber of SIEV is relatively greater compared with the pedicle side.