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Dive into the research topics where Hiroki Umezawa is active.

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Featured researches published by Hiroki Umezawa.


Journal of Plastic Reconstructive and Aesthetic Surgery | 2012

Comparison of pedicled and free anterolateral thigh flaps for reconstruction of complex defects of the abdominal wall: Review of 20 consecutive cases

Shuji Kayano; Minoru Sakuraba; Shimpei Miyamoto; Shogo Nagamatsu; Megumi Taji; Hiroki Umezawa; Yoshihiro Kimata

BACKGROUND The reconstruction of large, complex defects of the abdominal wall after the ablation of malignant tumours can be challenging. The transfer of an anterolateral thigh (ALT) flap is an attractive option. This study compared free ALT flaps and pedicled ALT flaps for abdominal wall reconstruction. METHODS From 1996 through 2011, 20 patients underwent abdominal wall reconstruction with ALT flaps. The flaps were pedicled in 12 patients and free in eight patients. Medical records were reviewed for complications and clinical and demographic data. Abdominal wall defects were classified into the following four groups: upper midline, lower midline, upper quadrants and lower quadrants. RESULTS Pedicled flaps were transferred to the upper midline region in one patient, the lower midline region in six patients and lower quadrants in five patients. Free flaps were transferred to the lower midline region in two patients, upper quadrants in four patients and lower quadrants in two patients. Mean reconstructive time was significantly longer with free flaps (6 h 32 min) than with pedicled flaps (4 h 55 min, p = 0.035). Although free flaps (mean size, 360 cm(2)) were larger than pedicled flaps (mean size, 289 cm(2)), the difference was not significant (p = 0.218). The rates of complications did not differ between free flaps and pedicled flaps. No total flap loss occurred, and there was partial loss of only a single pedicled flap, which was the flap furthest from the pivot point. Infections developed of two pedicled flaps and three free flaps. CONCLUSION This study suggests that complication rates do not differ between free and pedicled ALT flaps. The choice of flap depends on the size and location of the defect and the length of the vascular pedicle.


Journal of Plastic Reconstructive and Aesthetic Surgery | 2013

Analysis of immediate vascular reconstruction for lower-limb salvage in patients with lower-limb bone and soft-tissue sarcoma ☆

Hiroki Umezawa; Minoru Sakuraba; Shinpei Miyamoto; Shougo Nagamatsu; Shuji Kayano; Megumi Taji

BACKGROUND Limb amputation has historically been the first choice of treatment for patients with bone or soft-tissue sarcomas involving major blood vessels. However, recent advances in surgical technique have allowed limb-salvage surgery. We reviewed our experiences with limb-salvage surgery and immediate vascular reconstruction following en bloc resection of bone or soft-tissue sarcomas of the lower extremity. MATERIALS AND METHOD We reviewed 23 patients (15 male and eight female; mean age, 43.6 years) who underwent limb-salvage surgery and immediate vascular reconstruction. Details of surgical factors and postoperative complications were evaluated. RESULTS Reconstructed vessels remained patent in 21 cases. The rate of limb oedema was higher in patients who underwent only arterial reconstruction after arteriovenous resection. Twenty patients could walk well without crutches a few months after reconstructive surgery. All patients avoided amputation. Two patients died of disseminated disease within 3 years after surgery. CONCLUSION The high rate of limb oedema suggests that venous reconstruction is necessary after arteriovenous resection. Vascular reconstruction and musculocutaneous flap techniques are useful in limb-salvage surgery and are indicated for patients who have achieved good disease control. Evidence Rating Scale for Therapeutic Studies: Level III.


Journal of Nippon Medical School | 2015

A Comparison of Microsurgical Venous Anastomosis Techniques

Hiroki Umezawa; Rei Ogawa; Munenaga Nakamizo; Kazuhiko Yokoshima; Hiko Hyakusoku

BACKGROUND Successful vascular anastomosis is essential for the survival of transferred free tissue. Arterial anastomosis is typically uncomplicated because the lumen is easily maintained and the vessel walls have elasticity. Venous anastomosis, however, is more time consuming because the vessel walls are thin and extensible. This article describes, reviews, and compares 3 currently used venous anastomosis techniques. METHODS From April 2012 through January 2014, free tissue transfer and supercharging pedicled tissue transfer were performed in 107 and 10 patients, respectively, at our hospital. According to the anastomotic technique used, patients (83 men and 34 women; mean age, 60.6 years) were divided into interrupted suture, continuous suture, and microvascular anastomotic coupling device (MACD) groups. Medical records were reviewed, and postoperative results were analyzed. RESULTS The diameter of anastomosed veins did not differ significantly among the groups. However, among the interrupted suture, continuous suture, and MACD groups, there were significant differences in vascular anastomosis time (51, 43.9, and 29.5 minutes, respectively) and transferred tissue ischemic time (151.9, 139.1, and 117.5 minutes, respectively). Surgical site infection occurred in 9 patients, and flap necrosis occurred in 2 patients. However, complication rates did not differ significantly among the 3 groups. CONCLUSIONS The venous anastomosis technique does not affect the complication rate but does affect anastomosis time and flap ischemia time. On the basis of these results, we believe that the continuous suture and MACD techniques are easier and safer for venous anastomosis than is the traditional interrupted suture technique.


Plastic and Reconstructive Surgery | 2017

Experimental Rat Skin Flap Model That Distinguishes between Venous Congestion and Arterial Ischemia: The Reverse U-Shaped Bipedicled Superficial Inferior Epigastric Artery and Venous System Flap

Noriko Matsumoto; Masayo Aoki; Junichi Nakao; Wei-Xia Peng; Yoshihiro Takami; Hiroki Umezawa; Satoshi Akaishi; Ryuji Ohashi; Zenya Naito; Rei Ogawa

Background: The commonly used flap models have drawbacks that limit their usefulness. In the random skin flap model, flap necrosis is caused by both arterial and venous insufficiency. In the axial skin flap model, flap viability is easily affected by the pedicle blood flow and can result in complete necrosis. This study aimed to establish a new rat skin flap model that has a consistent flap survival rate and in which venous congestion and arterial ischemia can be readily distinguished macroscopically. Methods: Rats underwent reverse U-shaped bipedicled superficial epigastric artery flap elevation. The right superficial epigastric vessels formed the pedicle. In the control rats (n = 3), the left superficial epigastric vessels were left intact. In the ischemia group (n = 10), the left superficial epigastric artery was ligated. In the congestion group (n = 10), the left superficial epigastric vein was ligated. The flap was returned to the original site and sutured. The surrounding neovascularization was blocked by polyurethane film. Flap survival rates were evaluated on postoperative day 3. Results: The flaps in the ischemia and congestion groups were noticeably pale and violet, respectively. Flap necrosis was noted in the contralateral distal zone only. It started on postoperative day 2 in the ischemia and congestion groups. The mean flap survival rates of the control, ischemia, and congestion groups were 100 percent, 61.8 percent (range, 56.9 to 67.1 percent), and 42.3 percent (35.7 to 48.7 percent), respectively (all p < 0.001). Conclusions: The flap facilitated discrimination of the effects of ischemia and congestion. This new rat skin flap model is simple and easy to construct, and has a consistent flap survival rate.


Microsurgery | 2018

Reconstruction of elbow skin and soft tissue defects using perforator-pedicled propeller flaps

Junichi Nakao; Hiroki Umezawa; Rei Ogawa; Musa A. Mateev

The elbow is a challenging region to reconstruct functionally. Several closure methods for elbow wounds have been reported, including flap surgery. Here, we present the results obtained using a propeller flap pedicled by a posterior ulnar recurrence artery perforator (PURAP) or a radial collateral artery perforator (RCAP) for functional reconstruction of soft tissue defects in elbows.


Plastic and reconstructive surgery. Global open | 2017

Low-grade Cribriform Cystadenocarcinoma: A Review of the Literature and Case Report

Nao Wakabayashi; Hiroki Umezawa; Noriko Matsumoto; Yoko Endo; Zenya Naito; Rei Ogawa

Summary: Low-grade cribriform cystadenocarcinoma (LGCCC) is a rare tumor of the salivary gland that most often arises from the parotid gland. A 51-year-old man developed a small mass on the right parotid gland 5 years ago. A preoperative magnetic resonance image showed abnormal intensity, an atypical characteristic for such a tumor; therefore, the diagnosis was difficult. Thus, a superficial parotidectomy was performed as a total excisional biopsy to remove the tumor. Histopathological analyses revealed that the tumor was composed of a single cyst comprising cells containing mucosal fluid, with proliferation of large cells. Also, proliferation of the tumor epithelium showed a papillary cribriform pattern of proliferation with a partial ring form, and the tissue inside the tumor was replaced by a hematoma. Mild cellular atypia was observed. Immunostaining for S-100 was positive, and the Ki-67 ratio was <5%. These histopathological findings led to a diagnosis of LGCCC of the parotid gland. At 54 months after surgery, the patient has had no recurrence or facial palsy. LGCCC is a rare neoplasm of the salivary gland and is listed in the current World Health Organization classification (2005) as a variant of cystadenocarcinoma. This case suggests that a thorough preoperative examination can lead to better diagnosis of rare tumors, including LGCCC. Thus, if a plastic surgeon is to correctly diagnose and treat parotid grand tumors, including LGCCC, then a detailed preoperative examination, including imaging, a disease course review, a physical examination, and differential diagnosis, should be considered carefully.


Plastic and reconstructive surgery. Global open | 2016

Usefulness of the Clavien-Dindo Classification in Understanding the Limitations and Indications of Larynx-preserving Esophageal Reconstruction.

Hiroki Umezawa; Junichi Nakao; Takeshi Matsutani; Hiroaki Kuwahara; Marie Taga; Rei Ogawa

Background: The Clavien–Dindo (CD) classification is used to evaluate the severity of surgical complications. However, its usefulness in esophageal reconstruction has not been reported. To address this, this case series study used the CD classification to evaluate the complications after cervical esophageal reconstruction with free jejunum transfer or supercharged pedicled intestinal transfer. Methods: All consecutive patients who underwent esophageal cancer surgery with larynx-preserving free jejunum or pedicled ileocolic transfer in June 2012–December 2015 were identified. The postoperative complications were classified using the CD classification. Results: In total, 22 patients (20 men and 2 women; mean age, 63.3 years) underwent esophageal cancer reconstruction with larynx-preserving free jejunum transfer (n = 9) and supercharged pedicled intestinal transfer (n = 13). Seven patients underwent prophylactic tracheotomy. Four patients underwent emergent tracheotomy 1 or 5 days after surgery. The most frequent complication was recurrent nerve paralysis (RNP) (n = 8). Of these 8 RNP cases, 6 and 2 were classified as CD I and III complications, respectively. Pneumonia was the next most common complication (n = 7). Of these 7 pneumonia cases, 5 and 2 were classified as CD II and III, respectively. There were 2 cases of intestinal anastomosis leakage (CD II and III). On average, patients were able to start oral alimentation 15.1 (9–35) days after surgery. Conclusions: Our analysis with the CD classification suggested that vascularized free jejunum transfer or supercharge-drainage pedicled ileocolic transfer prevents postoperative intestinal anastomosis leakage and that prophylactic tracheotomy is especially indicated in cases with significant surgical damage in the cervical region.


Journal of Craniofacial Surgery | 2013

Vastus lateralis muscle flaps for monitoring buried anterolateral thigh flaps.

Shimpei Miyamoto; Shuji Kayano; Hiroki Umezawa; Masahide Fujiki; Minoru Sakuraba

Postoperative monitoring of buried anterolateral thigh flaps is difficult with standard methods. Although a monitoring skin flap based on a second cutaneous perforator is often used, it requires tedious dissection of 2 sets of perforators and cannot be used when a second perforator is absent. We present 2 patients who underwent head and neck reconstruction with buried anterolateral thigh flaps, which were monitored with a small, externalized segment of the vastus lateralis muscle accompanying the main skin island. Both flaps survived, and the monitoring muscle flaps remained pink throughout the postoperative period until removal. For monitoring, a vastus lateralis muscle flap has several advantages over a skin flap. This method obviates the need for dissecting a second cutaneous perforator and allows reliable monitoring regardless of the number of available cutaneous perforators. We believe this method is a versatile option for monitoring buried anterolateral thigh flaps.


Clinical Journal of Gastroenterology | 2018

Phlegmonous gastritis associated with advanced esophageal cancer.

Nobutoshi Hagiwara; Takeshi Matsutani; Hiroki Umezawa; Munenaga Nakamizo; Kazuhiko Yokoshima; Eriko Shinozuka; Tsutomu Nomura; Eiji Uchida

Phlegmonous gastritis is a rapidly progressive bacterial infection of the stomach wall. It has a high mortality rate and aggressive treatment, either with antibiotics or surgical resection, is required. Here, we report an extremely rare case of phlegmonous gastritis associated with advanced esophageal cancer. A 65-year-old Japanese man was urgently admitted to the hospital due to pyrexia and gastrointestinal symptoms. Abdominal computed tomography revealed widespread diffuse thickening of the gastric wall. On endoscopic examination, an ulcerative mass was detected at the lower thoracic esophagus, and a markedly elevated submucosal lesion was present in the middle of the stomach body. Biopsy specimens taken endoscopically from the esophageal tumor confirmed a diagnosis of squamous cell carcinoma. Gastric biopsy cultures were positive for Streptococcus viridans, leading to a diagnosis of phlegmonous gastritis associated with esophageal cancer. After the patient’s condition improved with preoperative antibiotic administration, we performed a thoracoscopic esophagectomy, a total gastrectomy and a reconstruction of the gastrointestinal tract using a pedicled right colon. Histological examination of the resected specimen confirmed that the gastric mass was compatible with a phlegmon.


Plastic and reconstructive surgery. Global open | 2016

Surgical Treatment of Rare Sclerosing Polycystic Adenosis of the Deep Parotid Gland.

Noriko Matsumoto; Hiroki Umezawa; Ryuji Ohashi; Wei-Xia Peng; Zenya Naito; Rei Ogawa

Summary: We experienced a rare case of sclerosing polycystic adenosis (SPA) arising in a parotid gland. A 33-year-old man who underwent unspecified surgery for a lesion in the left parotid gland 23 years ago presented with a lesion on the same site. Computed tomography scan revealed an encapsulated 3 × 2 cm lesion. Intraoperative findings showed that the tumor was embedded deep in the parotid gland. Marginal tumor excision was performed to preserve the facial nerve. Histopathological and immunohistochemical findings led to the final diagnosis of SPA. The surgery was not associated with any other complications. To date, 28 months after surgery, recurrence has not been observed. The treatment protocol of SPA has not yet been established. To make plastic surgeons familiar with this disease, we describe this case, which was successfully treated without any complications.

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Rei Ogawa

Nippon Medical School

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Minoru Sakuraba

Saitama Medical University

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