Publications by authors named "Hak Chang"

Article Synopsis
  • The study focuses on the increasing use of the DIEP flap for breast reconstruction and highlights the development of 3D models to aid in the surgical dissection process.
  • Collaboration among surgeons, radiologists, and 3D model makers was crucial in creating an accurate and user-friendly 3D DIEP model that can be accessed online via mobile devices.
  • The resulting 3D model improved visual clarity of vascular structures and allowed for personalized adjustments, ultimately making surgeries safer and easier, especially for less experienced surgeons.
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Background: In 2021, a meta-analysis showed fat graft retention varied from 26 to 83%. In a retrospective study including patients with Parry-Romberg syndrome, the younger age group had higher satisfaction scores (3.8 vs.

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Background: Cell-assisted acellular adipose matrix (AAM) transfer is a novel technique for soft tissue volume restoration, where AAM acts as a scaffold for tissue proliferation and promotes host cell migration, vascularization, and adipogenesis. This study aimed to evaluate the efficacy and safety of in vivo cell-assisted AAM transfer compared to hyaluronic acid (HA) filler injection.

Methods: Human adipose tissue was used to manufacture AAM, and murine adipose-derived stem cells (ASCs) were prepared.

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Background: We previously showed comparable volume effects of injections of acellular adipose matrix (AAM), an adipose tissue-derived extracellular matrix, and conventional fat grafting in a murine model. Thus, AAM could be a novel allogenic injectable product. However, its retention rate poses a concern, as repeated AAM injections may be required in some cases.

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The European Society for Radiotherapy and Oncology-Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) updated a new target volume delineation guideline for postmastectomy radiotherapy (PMRT) after implant-based reconstruction. This study aimed to evaluate the impact on breast complications with the new guideline compared to the conventional guidelines. In total, 308 patients who underwent PMRT after tissue expander or permanent implant insertion from 2016 to 2021 were included; 184 received PMRT by the new ESTRO-ACROP target delineation (ESTRO-T), and 124 by conventional target delineation (CONV-T).

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Background: Vascularized gastroepiploic lymph node transfer (VGLNT) is a well-accepted surgical treatment for restoring physiological function in chronic lymphedema. However, the inclusion of substantial lymph nodes (LNs) in the flap remains uncertain. This study aimed to identify the anatomical basis for reliable flap harvest for VGLNT.

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Background: The extracellular matrix isolated from adipose tissue, known as acellular adipose matrix (AAM), represents a novel biomaterial. AAM functions as a scaffold that not only supports stem cell proliferation and differentiation but also induces adipogenesis and angiogenesis. This study aims to investigate the volumetric effects and microenvironmental changes associated with injectable AAM in comparison to conventional fat grafting.

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Background: Infections following postmastectomy implant-based breast reconstruction (IBR) can compromise surgical outcomes and lead to significant morbidity. This study aimed to discern the timing of infections in two-stage IBR and associated risk factors.

Method: A review of electronic health records was conducted on 1096 breasts in 1058 patients undergoing two-stage IBR at Seoul National University Hospital (2015-2020).

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Refractory chylous ascites can cause significant nutritional and immunologic morbidity, but no clear treatment has been established. This article introduces a case of a 22-year-old female patient with an underlying lymphatic anomaly who presented with refractory chylous ascites after laparoscopic adnexectomy for ovarian teratoma which aggravated after thoracic duct embolization. Ascites (>3,000 mL/d) had to be drained via a percutaneous catheter to relieve abdominal distention and consequent dyspnea, leading to significant cachexia and weight loss.

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Diabetic foot ulcer and diabetic kidney disease are diabetes-related chronic vascular complications that strongly correlate with high morbidity and mortality. Although metformin potentially confers a wound-healing advantage, no well-established clinical evidence supports the benefit of metformin for diabetic foot ulcer. Thus, this study investigated the effect of metformin on diabetic foot ulcer from a large diabetic kidney disease cohort for the first time.

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Background: Nanofat and lipoconcentrate contain adipose-derived stem cells and growth factors, and have wide clinical applications in the regenerative field. This study aimed to investigate the microenvironmental changes associated with nanofat and lipoconcentrate.

Methods: Conventional fat, nanofat, or lipoconcentrate (0.

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Article Synopsis
  • * Rats received human skin grafts and were then subjected to either triple PBS injections, one ADSC injection with double PBS injections, or triple ADSC injections to evaluate immunomodulatory effects.
  • * Results showed that triple ADSC injections significantly improved graft survival by reducing immune cell infiltration and decreasing proinflammatory cytokines while increasing immunosuppressive factors, compared to fewer injections.
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Background: Since nanofat was first introduced by Tonnard in 2013, numerous studies have reported positive findings with its use; however, concerns exist regarding its effects and mechanisms, and the various methods used to generate nanofat also remain unclear. The authors conducted a systematic review to evaluate the efficacy of nanofat grafting alone in plastic and reconstructive surgery.

Methods: The MEDLINE, Embase, Cochrane Central, Web of Science, and Scopus databases were searched for studies related to the use of nanofat grafting alone in plastic and reconstructive surgery.

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Background: 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.

Methods: 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 20 min.

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Background: The most common concern in nipple reconstruction is the loss of long-term nipple projection. This study aimed to demonstrate a novel method of nipple reconstruction using a modified C-V flap combined with purse-string sutures in the nipple base to maintain nipple projection.

Methods: From January 2018 to July 2021, patients who underwent nipple reconstruction using the novel modified C-V flap method and conventional C-V flap were retrospectively reviewed.

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Article Synopsis
  • Vasopressors are commonly used in free flap surgeries, particularly in up to 85% of cases, leading to concerns about complications due to vasoconstriction.
  • A pilot study compared the effects of norepinephrine and phenylephrine on blood flow during TRAM flap breast reconstruction, excluding patients with certain health issues.
  • Results indicated norepinephrine maintained flap perfusion better than phenylephrine, but further studies are necessary for validation.
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Hepatic artery thrombosis (HAT) after liver transplantation is associated with a marked increase in morbidity, leading to graft and patient loss. We evaluated the outcomes of adult living donor liver transplantation patients with HAT under an aggressive surgical intervention. A total of 1355 recipients underwent adult living donor liver transplantation at the Seoul National University Hospital.

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Background: Cell-assisted lipotransfer, a fat graft mixed with adipose-derived stromal cells, is known to enhance fat graft retention. Previously, the authors showed that intravenous injection of adipose-derived stromal cells can improve the survival of grafted fat. In the present study, the authors investigated the effects of a secondary intravenous injection of adipose-derived stromal cells on fat grafting.

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Article Synopsis
  • - The research on vascular and lymphatic systems is crucial in reconstructive surgery, with key historical figures like Harvey, Manchot, and Salman contributing significantly to our understanding of cutaneous vasculature and vascular territories.
  • - Key advancements in flap techniques, such as axial and random pattern flaps by McGregor and Morgan, as well as the angiosome concept by Taylor and Palmer, highlight the importance of arterial and venous systems for successful surgical outcomes.
  • - The understanding and imaging of the lymphatic system, which was discovered later, has evolved significantly, with modern techniques like photoacoustic imaging allowing for enhanced visualization and study of its architecture.
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The aim of the present study was to analyze the consequences of partial free latissimus dorsi muscle flap with nerve splitting technique (Partial LD transfer) for facial reanimation and compare outcomes according to innervation method (singer versus dual innervation). Patients with complete unilateral facial paralysis underwent either the single (ipsilateral masseteric nerve only) or dual (ipsilateral masseteric nerve plus contralateral buccal branch of the facial nerve) nerve innervation method for facial reanimation. An assessment was carried out to compare the outcomes between the single and dual innervation.

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The aim of the study was to analyze the efficacy of retrograde innervation of single-stage free latissimus dorsi (LD) flap for facial reanimation by the distal stump of thoracodorsal nerve (TDN). After the main trunk of TDN was split in half to preserve the function of transverse branch, the proximal stump was coapted with the contralateral facial nerve, and the distal stump was coapted with the ipsilateral masseteric nerve, or vice versa. The length of each nerve stump and the time required for voluntary and spontaneous muscle contraction after surgical treatment were reviewed.

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In lower abdominal flap representing transverse rectus abdominis musculocutaneous (TRAM) flap or deep inferior epigastric perforator (DIEP) flap, superficial inferior epigastric vein (SIEV) exists as superficial and independent venous system from deep system. The superficial venous drainage is dominant despite a dominant deep arterial supply in anterior abdominal wall. As TRAM or DIEP flaps began to be widely used for breast reconstruction, venous congestion issue has been arisen.

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