Details of a Researcher - Obara, Hideaki

Papers - Obara, Hideaki

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A short review of popliteal artery entrapment syndrome

Obara H., Gupta P.C., Levien L., Mistry P., Bollineni V., Shaw P.M.

Jvs Vascular Insights 3 2025.01

Background: Popliteal artery entrapment syndrome (PAES) is a rare cause of lower limb ischemia, typically affecting young adults. Case Report: This case report describes a 22-year-old man with severe left calf claudication due to type II PAES, confirmed by imaging. Surgical treatment involved resection of the aberrant gastrocnemius muscle and popliteal artery reconstruction using the great saphenous vein. Postoperative recovery was uneventful, with complete symptom resolution and no recurrence at 2-year follow-up. Conclusions: PAES should be considered in young patients with unexplained claudication, and surgery offers effective long-term outcomes. This article also briefly discusses the classification, diagnosis, and treatment strategies for PAES.

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Contemporary management of arterial thoracic outlet syndrome

Gupta P.C., Obara H., Jindal R., Shah S., Mahapatra S., Vamsi Krishna Y., Sekar N., Vasudevan T.

Jvs Vascular Insights 3 2025.01

Background: Arterial thoracic outlet syndrome (ATOS), although the least common of thoracic outlet syndromes (<1%), often presents with severe upper limb ischemia as a sequel of subclavian artery (SA) dilatation, intimal injury, thrombus formation, and distal embolization, all secondary to extrinsic compression. Methods: Literature was reivewed to see the changing trends and current managment of ATOS. Results: The syndrome affects young adults and women more often than men. Although patients often present with a bony prominence in the neck or upper limb ischemia, rarely they may present with posterior circulation stroke or an asymptomatic ATOS may be detected during evaluation of the contralateral limb. Surgical decompression of the thoracic outlet along with treatment of the involved SA is the accepted treatment modality. Arterial thoracic syndrome is almost always operated via the supraclavicular or paraclavicualr and occasionally transaxillary approach. Stenting still does not find any significant role in the treatment of this disease. This review discusses the clinical presentation, evaluation, and surgical therapy including ways to repair the SA. It also discusses the common complications and their management. Finally, the outcomes of surgery for ATOS are discussed. Conclusions: ATOS can cause significant symptoms and disability. Diagnosis is based on clinical evaluation and imaging and must show evidence of injury to SA. Treatment is surgical and best performed using the supraclavicular or paraclavicular approach and offers good long-term results. A nonculprit first rib may be preserved as evidenced by multiple series showing good medium- to long-term results, and subclavian aneurysm can be treated by different methods.

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Positioning Control for Voice Coil Motor Using Unbalanced Multilevel Inverter Topology

Takei, G; Obara, H; Haneda, R; Nozaki, T

2025 IEEE INTERNATIONAL CONFERENCE ON MECHATRONICS, ICM 2025

ISSN 2837-1143

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Improved survival of pediatric deceased donor liver transplantation recipients after introduction of the pediatric prioritization system: Analysis of data from a Japanese national survey

Takemura Y., Shinoda M., Kasahara M., Sakamoto S., Hatano E., Okamoto T., Ogura Y., Sanada Y., Matsuura T., Ueno T., Obara H., Soejima Y., Umeshita K., Eguchi S., Kitagawa Y., Egawa H., Ohdan H., Ogawa E., Ito T., Sakuma Y., Yoshizumi T., Eguchi H., Shimamura T., Mita A., Hibi T., Fukumoto T., Hasegawa K., Marubashi S., Umeda Y., Nobori S., Hasegawa Y., Yamada Y., Kitago M.

Journal of Hepato Biliary Pancreatic Sciences 31 ( 11 ) 782 - 797 2024.11

ISSN 18686974

Background: In Japan, there has never been a national analysis of pediatric deceased donor liver transplantation (pDDLT) based on donor and recipient factors. We constructed a Japanese nationwide database and assessed outcomes of pDDLT focusing on the pediatric prioritization system introduced in 2018. Methods: We collected data on pDDLTs (<18 years) performed between 1999 and 2021 from the Japan Organ Transplant Network and Japanese Liver Transplantation Society, identified risk factors for graft survival and compared the characteristics and graft survival in pDDLTs conducted before and after the introduction of the pediatric prioritization system. Results: Overall, 112 cases of pDDLT were included, with a 1-year graft survival rate of 86.6%. Four poor prognostic factors were identified: recipient intensive care unit stay, model for end-stage liver disease/pediatric end-stage liver disease score, donor cause of death, and donor total bilirubin. After the introduction of the system, allografts from pediatric donors were more reliably allocated to pediatric recipients and the annual number of pDDLTs increased. The 1-year graft survival rate improved significantly as did pDDLT conditions indicated by the risk factors. Conclusions: Under the revised allocation system, opportunities for pDDLT increased, resulting in favorable recipient and donor conditions and improved survival.

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Long-Term Outcomes of a Japanese Prospective Multicenter Registry Using a Heparin-Bonded Expanded Polytetrafluoroethylene Graft for Above-the-Knee Femoropopliteal Bypasses

Fujimura N., Obara H., Matsubara K., Toya N., Isogai N., Ogino H., Fujii T., Kudo T., Kanaoka Y., Harada H., Uchiyama H., Guntani A., Shimogawara T., Watada S., Shibutani S., Ohki T.

Circulation Journal 88 ( 10 ) 1656 - 1663 2024.10

ISSN 13469843

Background: Despite the widespread use of PROPATEN®, a bioactive heparin-bonded expanded polytetrafluoroethylene graft, in bypass surgery, there are only a few reports of long-term results. We evaluated the long-term results of PROPATEN® use for above-knee femoropopliteal bypass (AKFPB). Methods and Results: After PROPATEN®-based AKFPB, patients were prospectively registered at 20 Japanese institutions between July 2014 and October 2017 to evaluate long-term results. During the median follow-up of 76 months (interquartile range 36–88 months) for 120 limbs (in 113 patients; mean [±SD] age 72.7±8.1 years; 66.7% male; ankle-brachial index [ABI] 0.45±0.27; lesion length 26.2±5.7 cm; chronic limb-threatening ischemia in 45 limbs), there were 8 major amputations; however, clinical improvement was sustained (mean [±SD] ABI 0.87±0.23) and the Rutherford classification grade improved in 105 (87.5%) limbs at the latest follow-up. At 8 years, the primary patency, freedom from target-lesion revascularization, secondary patency, survival, and amputation-free survival, as estimated by the Kaplan-Meier method, were 66.3±4.8%, 71.5±4.4%, 86.5±3.4%, 53.1±5.0%, and 47.4±5.3%, respectively. Conclusions: This multicenter prospective registry-based analysis showed sustained excellent clinical improvement and secondary patency for up to 8 years following PROPATEN®-based AKFPB. PROPATEN® constitutes a durable and good revascularization option for complex superficial femoral artery lesions, especially when endovascular treatment is inappropriate or an adequate venous conduit is unavailable.

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A novel scoring system to predict short-term mortality after living donor liver transplantation for acute liver failure

Shimata K., Yoon Y.I., Hibi T., Morinaga J., Narayanan A.K., Toshima T., Ito T., Akamatsu N., Kotera Y., Hong S.K., Hasegawa Y., Umeda Y., Reddy M.S., Ong A.D.L., Sivaprasadan S., Varghese J., Sugawara Y., Chen C.L., Nakayama N., Mochida S., Tanaka A., Suh K.S., Ikegami T., Lee K.W., Lee S.G., Sudhindran S., Yoshizumi T., Hatano E., Okumura S., Hasegawa K., Egawa H., Obara H., Yasui K., Ogura Y., Jobara K., Nitta H., Katagiri H., Otsuka M., Kuboki S., Eguchi S., Hara T., Eguchi H., Sasaki K., Aoki T., Ohdan H., Ohira M., Takada Y., Ogawa K., Fukumoto T., Kuramitsu K., Saiura A., Ichida H., Hashimoto T., Marubashi S., Sato N., Ushigome H., Harada S., Soejima Y., Masuda Y., Shimada M., Saitou Y., Taketomi A., Goto R., Shimamura T., Mizuno S., Tanemura A., Endo I., Unno M., Miyagi S., Okamura Y., Aramaki O., Hakamada K., Ishido K., Kato Y., Takahara T., Takatsuki M., Ono S.

American Journal of Transplantation 24 ( 10 ) 1857 - 1867 2024.10

ISSN 16006135

Liver transplantation is often the only lifesaving option for acute liver failure (ALF); however, the predictors of short-term mortality (death within one year) after living donor liver transplantation (LDLT) for ALF have yet to be defined. We retrospectively collected patients ≥18 years old who underwent LDLT for ALF between 2010 and 2020 at 35 centers in Asia. Univariate and multivariate logistic regression analyses were conducted to identify the clinical variables related to short-term mortality and establish a novel scoring system. The Kaplan-Meier method was performed to explore the association between the score and overall survival. Of the 339 recipients, 46 (13.6%) died within 1 year after LDLT. Multivariate analyses revealed 4 independent risk factors for death: use of vasopressors or mechanical ventilation, the higher model for end-stage liver disease score, and a lower graft-to-recipient weight ratio. The internally validated c-statistic of the short-term mortality after transplant (SMT) score derived from these 4 variables was 0.80 (95% confidence interval: 0.74-0.87). The SMT score successfully stratified recipients into low-, intermediate-, and high-risk groups with 1-year overall survival rates of 96%, 80%, and 50%, respectively. In conclusion, our novel SMT score based on 4 predictors will guide ALF recipient and living donor selection.

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Characteristics, Antithrombotic Patterns, and Prognostic Outcomes in Claudication and Critical Limb-Threatening Ischemia Undergoing Endovascular Therapy

Kawarada O., Zen K., Hozawa K., Obara H., Matsubara K., Yamamoto Y., Doijiri T., Tamai N., Ito S., Higashimori A., Kawasaki D., Doi H., Matsushita K., Tsukahara K., Noda K., Shimpo M., Tsuda Y., Sonoda S., Taniguchi T., Waseda K., Munehisa M., Taguchi E., Kinjo T., Sasaki Y., Yuba K., Yamaguchi S., Nakagami T., Ayabe S., Sakamoto S., Yagyu T., Ogata S., Nishimura K., Motomura H., Noguchi T., Ishihara M., Ogawa H., Yasuda S.

Journal of Endovascular Therapy 31 ( 4 ) 622 - 633 2024.08

ISSN 15266028

Purpose: The underlying difference between intermittent claudication (IC) and critical limb-threatening ischemia (CLTI) still remains unclear. This prospective multicenter observational study aimed to clarify differences in clinical features and prognostic outcomes between IC and CLTI, and prognostic factors in patients undergoing endovascular therapy (EVT). Materials and Methods: A total of 692 patients with 808 limbs were enrolled from 20 institutions in Japan. The primary measurements were the 3-year rates of major adverse cardiovascular event (MACE) and reintervention. Results: Among patients, 79.0% had IC and 21.0% had CLTI. Patients with CLTI were more frequently women and more likely to have impaired functional status, undernutrition, comorbidities, hypercoagulation, hyperinflammation, distal artery disease, short single antiplatelet and long anticoagulation therapies, and late cilostazol than patients with IC. Aortoiliac and femoropopliteal diseases were dominant in patients with IC and infrapopliteal disease was dominant in patients with CLTI. Patients with CLTI underwent less frequently aortoiliac intervention and more frequently infrapopliteal intervention than patients with IC. Longitudinal change of ankle-brachial index (ABI) exhibited different patterns between IC and CLTI (pinteraction=0.002), but ABI improved after EVT both in IC and in CLTI (p<0.001), which was sustained over time. Dorsal and plantar skin perfusion pressure in CLTI showed a similar improvement pattern (pinteraction=0.181). Distribution of Rutherford category improved both in IC and in CLTI (each p<0.001). Three-year MACE rates were 20.4% and 42.3% and 3-year reintervention rates were 22.1% and 46.8% for patients with IC and CLTI, respectively (log-rank p<0.001). Elevated D-dimer (p=0.001), age (p=0.043), impaired functional status (p=0.018), and end-stage renal disease (p=0.019) were independently associated with MACE. After considering competing risks of death and major amputation for reintervention, elevated erythrocyte sedimentation rate (p=0.003) and infrainguinal intervention (p=0.002) were independently associated with reintervention. Patients with CLTI merely showed borderline significance for MACE (adjusted hazard ratio 1.700, 95% confidence interval 0.950–3.042, p=0.074) and reintervention (adjusted hazard ratio 1.976, 95% confidence interval 0.999–3.909, p=0.05). Conclusions: The CLTI is characterized not only by more systemic comorbidities and distal disease but also by more inflammatory coagulation disorder compared with IC. Also, CLTI has approximately twice MACE and reintervention rates than IC, and the underlying inflammatory coagulation disorder per se is associated with these outcomes. Clinical Impact: The underlying difference between intermittent claudication (IC) and critical limb-threatening ischemia (CLTI) still remains unclear. This prospective multicenter observational study, JPASSION study found that CLTI was characterized not only by more systemic comorbidities and distal disease but also by more inflammatory coagulation disorder compared to IC. Also, CLTI had approximately twice major adverse cardiovascular event (MACE) and reintervention rates than IC. Intriguingly, the underlying inflammatory coagulation disorder per se was independently associated with MACE and reintervention. Further studies to clarify the role of anticoagulation and anti-inflammatory therapies will contribute to the development of post-interventional therapeutics in the context of peripheral artery disease.

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Quantitative evaluation of lower limb varicose veins using photoacoustic imaging

Urano M., Nagae K., Matsuda S., Matsubara K., Yagi T., Imanishi N., Aiso S., Obara H., Jinzaki M.

Journal of Medical Ultrasonics 51 ( 3 ) 507 - 516 2024.07

ISSN 13464523

Purpose: Varicose veins in the lower extremities are dilated subcutaneous varicose veins with a diameter of ≥ 3 mm, caused by increased venous pressure resulting from backflow of blood due to venous valve insufficiency (Gloviczki in Handbook of venous disorders: guidelines of the American venous forum, Hodder Arnold, London, 2009). When diagnosing varicose veins, the shape and thickness of the blood vessels should be accurately visualized in three dimensions. In this study, we investigated a new method for numerical evaluation of vascular morphology related to varicose veins in the lower extremities, using a photoacoustic imaging (PAI) system, which can acquire high-resolution and three-dimensional images noninvasively. Methods: Nine patients with varicose veins participated in the study, and their images were captured using an optical camera and PAI system. We visualized the vascular structure, created a blood presence density (BPD) heat map, and examined the correlation between BPD and location of varicose veins. Results: The obtained photoacoustic (PA) images demonstrated the ability of this method to visualize vessels ranging from as small as 0.2 mm in diameter to large, dilated vessels in three dimensions. Furthermore, the study revealed a correlation between the high-density part of the BPD heat map generated from the PAI images and the presence of varicose veins. Conclusion: PAI is a promising technique for noninvasive and accurate diagnosis of varicose veins in the lower extremities. By providing valuable information on the morphology and hemodynamics of the varicose veins, PAI may facilitate their early detection and treatment.

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Early-onset hepatic veno-occlusive disease after liver transplantation: an institutional experience and analysis of a literature-based cohort

Endo Y., Shinoda M., Maehara J., Hibi T., Hasegawa Y., Obara H., Kitago M., Ojima H., Tanabe M., Kitagawa Y.

Surgery Today 54 ( 7 ) 670 - 682 2024.07

ISSN 09411291

Purpose: Hepatic veno-occlusive disease (HVOD) after liver transplantation (LT) is almost always a fatal complication. We assessed the outcomes of HVOD in a single institute and analyzed a literature-based cohort. Methods: We reviewed the medical records of recipients of LT performed between 1995 and 2020 at our institute and the literature on HVOD after LT. We then analyzed the clinical features based on a “pooled” cohort of cases identified in our institute and reported in the literature. Results: HVOD was diagnosed in 3 of 331 LT recipients, all of whom died in hospital, on days 164, 12, and 13, respectively. Our comprehensive review of the literature, as well as our cases, identified eight cases of HVOD that developed within 14 days after LT (early-onset type). Early-onset HVOD had a significantly worse prognosis than HVOD that developed beyond 2 weeks after LT (non-early-onset type), which was identified in 22 cases (25.0% vs. 86.1% of the 3-month graft survival rate). The most common causes of early-onset and non-early-onset types were acute cellular rejection (50%) and drug-induced disease (50%), respectively. Conclusion: Early-onset HVOD developing within 14 days after LT has a poor prognosis.

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Endovascular Treatment as an Alternative to Bypass Surgery for Juxtarenal Aortic Occlusion: Results from the CHAOS (CHronic Abdominal Aortic Occlusion, ASian Multicenter) Registry

Kawai Y., Fujimura N., Obara H., Ichihashi S., Kudo T., Hozawa K., Yamaoka T., Kato T., Kawarada O., Banno H.

Annals of Vascular Surgery 104 174 - 184 2024.07

ISSN 08905096

Background: Juxtarenal aortic occlusion (JRAO), in which the occlusion of the aorta extends to just below the renal artery, is often treated by bypass surgery because of concerns about the risk of procedural failure and fatal embolization to abdominal organs when treated with endovascular treatment (EVT). This study assessed the outcome of EVT for JRAO compared with aorto-biiliac /aorto-bifemoral (AOB) or axillo-bifemoral (AXB) bypass. Methods: A retrospective review of an international database created by 30 centers in Asia (CHronic Abdominal Aortic Occlusion, ASian Multicenter registry) was performed for patients who underwent revascularization for chronic total occlusion of the infrarenal aorta from 2007 to 2017. Of the 436 patients, 130 with JRAO (Forty-seven AOBs, 32 AXBs, and 51 EVTs) from 25 institutions were included in this study. Results: Patients were significantly older in the AXB and EVT groups and more malnourished in the EVT group than the AOB group. EVT was attempted but failed in 1 patient. Seven patients (1 [2.1%] in the AOB group, 1 [3.1%] in the AXB group, and 5 [9.8%] in the EVT group) died during hospitalization, but most of the causes in the EVT group were not related to the revascularization procedure. No visceral embolism was observed, which had been concerned, even though protection was performed only in 2 cases of the EVT group. At the latest follow-up (median duration 3.0 years), the ankle-brachial pressure index was significantly higher in the order of AOB, EVT, and AXB. At 4 years, the estimated primary and secondary patency rates of the AOB group (87.5% and 90.3%, respectively) were significantly higher than the AXB group (66.7% and 68.6%, respectively). Conclusions: AOB remains the gold standard and should be the first choice for acceptable risk patients. For frail patients, EVT is a good option and likely preferable as a first-line treatment compared to AXB.

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Protective Effects of Hydrogen Gas Inhalation for Hindlimb Ischaemia–Reperfusion Injury in a Mouse Model

Hayashi M., Obara H., Matsuda S., Homma K., Sasaki J., Matsubara K., Higuchi M., Sano M., Masugi Y., Kitagawa Y.

European Journal of Vascular and Endovascular Surgery 68 ( 1 ) 120 - 128 2024.07

ISSN 10785884

Objective: Ischaemia–reperfusion (I/R) injury is a severe post-operative complication that triggers an inflammatory response and causes severe damage. Hydrogen gas has anti-oxidant and anti-apoptotic properties and has been shown to be safe in humans. The study aimed to investigate whether hydrogen gas protects against skeletal muscle I/R injury. Methods: Experimental basic research using mice. A total of 160 eight to 10 week old albino laboratory bred strain of house mice (25.8 ± 0.68 g) were used in this study. The mice were cable tied to the hindlimb under anaesthesia and then placed in an anaesthesia box filled with air and 2% isoflurane (control group); 80 mice were additionally subjected to 1.3% hydrogen gas in this mix (hydrogen group). After two hours, the cable ties were removed to initiate reperfusion, and hydrogen inhalation lasted for six hours in the hydrogen group. After six hours, the mice were taken out of the box and kept in cages under standard conditions until time for observation at 16 different time points after reperfusion: zero, two, four, six, eight, and 10 hours and one, two, three, four, five, six, seven, 14, 21, and 28 days. Five mice were sacrificed using excess anaesthesia at each time point, and the bilateral hindlimb tissues were harvested. The inflammatory effects of the I/R injury were assessed by evaluating serum interleukin-6 concentrations using enzyme linked immunosorbent assay, as well as histological and immunohistochemical analyses. Untreated mice with I/R injury were used as controls. Results: Hydrogen gas showed protective effects associated with a reduction in inflammatory cell infiltration (neutrophils, macrophages, and lymphocytes), a reduced area of damaged muscle, maintenance of normal muscle cells, and replacement of damaged muscle cells with neoplastic myocytes. Conclusion: Inhalation of hydrogen gas had a protective effect against hindlimb I/R injury in mice, in part by reducing inflammatory cell infiltration and in part by preserving normal muscle cells.

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Prognostic factors after open and endovascular repair for infected native aneurysms of the abdominal aorta and common iliac artery

Hosaka A., Takahashi A., Kumamaru H., Miyata H., Miyata H., Azuma N., Obara H., Miyata T., Obitsu Y., Zempo N., Komori K., Shigematsu K., Inoue Y., Okazaki J., Obara H., Satokawa H., Sugimoto I., Fujimura N., Mii S., Morikage N., Yamaoka T.

Journal of Vascular Surgery 79 ( 6 ) 1379 - 1389 2024.06

ISSN 07415214

Objective: Infected native aneurysms (INAs) of the abdominal aorta and iliac arteries are uncommon, but potentially fatal. Endovascular aneurysm repair (EVAR) has recently been introduced as a durable treatment option, with outcomes comparable to those yielded by conventional open repair. However, owing to the rarity of the disease, the strengths and limitations of each treatment remain uncertain. The present study aimed to separately assess post-open repair and post-EVAR outcomes and to clarify factors affecting the short-term and late prognosis after each treatment. Methods: Using a nationwide clinical registry, we investigated 600 patients treated with open repair and 226 patients treated with EVAR for INAs of the abdominal aorta and/or common iliac artery. The relationships between preoperative or operative factors and postoperative outcomes, including 90-day and 3-year mortality and persistent or recurrent aneurysm-related infection, were examined. Results: Prosthetic grafts were used in >90% of patients treated with open repair, and in situ and extra-anatomic arterial reconstruction was performed in 539 and 57 patients, respectively. Preoperative anemia and imaging findings suggestive of aneurysm-enteric fistula were independently associated with poor outcomes in terms of both 3-year mortality (hazard ratio [HR], 1.62; 95% confidence interval [CI], 1.01-2.62; P =.046, and HR, 2.24; 95% CI, 1.12-4.46; P =.022, respectively) and persistent or recurrent infection (odds ratio [OR], 2.16; 95% CI, 1.04-4.49; P =.039, and OR, 4.96; 95% CI, 1.81-13.55; P =.002, respectively) after open repair, whereas omental wrapping or packing and antibiotic impregnation of the prosthetic graft for in situ reconstruction contributed to improved 3-year survival (HR, 0.60; 95% CI, 0.39-0.92; P =.019, and HR, 0.53; 95% CI, 0.32-0.88; P =.014, respectively). Among patients treated with EVAR, abscess formation adjacent to the aneurysm was significantly associated with the occurrence of persistent or recurrent infection (OR, 2.24; 95% CI, 1.06-4.72; P =.034), whereas an elevated preoperative white blood cell count was predictive of 3-year mortality (HR, 1.77; 95% CI, 1.00-3.13; P =.048). Conclusions: Profiles of prognostic factors differed between open repair and EVAR in the treatment of INAs of the abdominal aorta and common iliac artery. Open repair may be more suitable than EVAR for patients with concurrent abscess formation.

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Noninvasive graft monitoring using donor-derived cell-free DNA in Japanese liver transplantation

Kanamori H., Yamada Y., Ito Y., Shirosaki K., Yamagishi S., Maeda Y., Kudo Y., Umeyama T., Takahashi N., Kato M., Hasegawa Y., Matsubara K., Shinoda M., Obara H., Irie R., Tsujikawa H., Okita H., Nguyen P.T., Saigo K., Mitsunaga S., Inoue I., Kitagawa Y., Kuroda T.

Hepatology Research 54 ( 3 ) 300 - 314 2024.03

ISSN 13866346

Aim: To evaluate the use of donor-derived cell-free DNA (dd-cfDNA) in diagnosing graft injuries in Japanese liver transplantation (LTx), including family-related living donors. Methods: A total of 321 samples from 10 newly operated LTx recipients were collected to monitor the early dynamics of dd-cfDNA levels after LTx. Fifty-five samples from 55 recipients were collected during protocol biopsies (PB), whereas 36 samples from 27 recipients were collected during event biopsies, consisting of 11 biopsy-proven acute rejection (AR), 20 acute dysfunctions without rejection (ADWR), and 5 chronic rejections. The levels of dd-cfDNA were quantified using a next-generation sequencer based on single nucleotide polymorphisms. Results: The dd-cfDNA levels were elevated significantly after LTx, followed by a rapid decline to the baseline in patients without graft injury within 30 days post-LTx. The dd-cfDNA levels were significantly higher in the 11 samples obtained during AR than those obtained during PB (p < 0.0001), which decreased promptly after treatment. The receiver operator characteristic curve analysis of diagnostic ability yielded areas under the curve of 0.975 and 0.897 for AR (rejection activity index [RAI] ≥3) versus PB and versus non-AR (ADWR + PB). The dd-cfDNA levels during AR were elevated earlier and correlated more strongly with the RAI (r = 0.740) than aspartate aminotransferase/alanine aminotransferase. The dd-cfDNA levels were neither associated with graft fibrosis based on histology nor the status of donor-specific antibodies in PB samples. Conclusions: Donor-derived cell-free DNA serves as a sensitive biomarker for detecting graft injuries in LTx. Further large-scale cohort studies are warranted to optimize its use in differentiating various post-LTx etiologies.

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Impact of wound management strategies after revascularization for chronic limb-threatening ischemia

Shintani T., Obara H., Matsubara K., Hayashi M., Kita H., Ono S., Watada S., Kikuchi N., Sekimoto Y., Torizaki Y., Asami A., Fujii T., Hayashi K., Harada H., Fujimura N., Hosokawa K., Nakatani E., Kitagawa Y.

Journal of Vascular Surgery 79 ( 3 ) 632 - 641.e3 2024.03

ISSN 07415214

Objective: There is no established consensus or guidelines for wound management after revascularization for patients with chronic limb-threatening ischemia (CLTI) without severe infection. This study is designed to evaluate the clinical effect of the wound management strategy on toe wounds after revascularization for CLTI. Methods: This retrospective cohort study was performed at eight institutions affiliated with Keio University School of Medicine in Japan and included 261 patients who underwent revascularization for CLTI between April 2019 and July 2021. We identified 132 patients with toe wounds from the database who had restored in-line blood flow to the foot. Patients were divided into two groups by the timing of toe resection after revascularization, which dictated the wound management policy. Group A (62 patients) underwent early toe amputation for suspected osteomyelitis, whereas group B (70 patients) underwent watchful waiting. The primary outcome was wound healing after revascularization; the secondary outcome was major amputation. We compared outcomes between groups A and B after propensity score matching. Results: Using propensity score matching, each patient in group A (33 patients) was matched with a patient in group B (33 patients). Wound healing in matched group A was significantly better than that in matched group B (respectively: 1-year wound healing rate: 90.0% vs 68.2%, P < .001; median wound healing time: 65 days vs 258 days, P < .01). Although five major amputations were necessary in matched group B, none were required in matched group A (P = .05). The high rate of major amputations in group B was attributed to the sudden exacerbation of infection. Limb salvage rate in matched group A exceeded matched group B (100.0% vs 90.5%: 1-year limb salvage rate, P = .02). Conclusions: Early toe amputation for highly suspected osteomyelitis in patients with CLTI with toe wounds may expedite wound healing compared with watchful waiting, potentially avoiding unnecessary major amputation. Considering the wound management strategy is crucial when evaluating wound healing outcomes in patients with CLTI with revascularization.

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Evaluation of a web-based surgical training approach and insights from the Distal Bypass Competition 2021 using a simulator kit

Kikuchi S., Komai H., Obara H., Abe K., Ohki T., Mii S., Park Y., Hoshina K., Yamaoka T., Deguchi J., Kodama A., Kokubo T., Kaneko K., Guntani A., Miyama N., Omine T., Fujimura N., Kan C.D., Kim J.Y., Lang W., Conte M.S., Azuma N.

Jvs Vascular Insights 2 2024.01

Objective: The study aimed to assess a novel web-based surgical training approach among young vascular surgeons and validate web-based evaluation methods for assessing anastomosis skills through the online Distal Bypass Competition (DBC). Methods: The OSATS was used to assess anastomosis proficiency using a simulator among 42 participants (17 junior and 25 senior surgeons) in the DBC 2021. An initial evaluation of basic anastomosis skills was conducted via recorded videos, comparing OSATS scores with instructor-derived impression-based scores (Comprehensive Evaluation Score [CES]) during the nomination round. Real-time evaluations conducted over Zoom focused on assessing technical and composition scores of the anastomoses to determine finalists. The ice-skating method addresses potential variability among judges by excluding the highest and lowest scores for each procedural element from the final evaluation. This method, demonstrated in real time, provides trainees with valuable feedback on which movements are highly rated, enhancing the educational impact. Evaluation criteria included precision in needlework, external appearance, handling of the intima, and internal morphology of the anastomosis. Furthermore, voluntary survey questionnaires were administered to gather participant feedback on their experience with DBC 2021. Results: The OSATS was associated with a lower coefficient of variation (CV) than was the CES (0.19 ± 0.07 vs 0.24 ± 0.09) (P = .01) with regard to the evaluation of basic anastomotic skills in the nomination round. Interestingly, there was no significant difference in CV between the Procedural Element Score based on OSATS and CES in the senior class (0.16 ± 0.06 vs 0.22 ± 0.09) (P = .13), but a significant difference was particularly evident in the junior class (0.12 ± 0.07 vs 0.27 ± 09) (P = .03). Lower scores were associated with higher CVs in both classes, but the OSATS improved the CV among participants who had inadequate anastomosis skills. In real-time evaluation, composition scores exhibited higher CVs compared with technical scores, even among high-scoring participants. Notably, the internal morphology of the anastomosis had the largest CV in the composition scores. The ice-skating method decreased the CV as compared with the original data evaluated using the OSATS (0.15 ± 0.04 vs 0.09 ± 0.02 for the technical score [P < .01] and .18 ± 1.00 vs 0.07 ± 0.05 for the composition score [P = .03]); accordingly, the ice-skating method was more conducive to objective, real-time evaluation. The results of the post-DBC survey indicated that 89% of participants reported increased training time, and one-half of these participants indicated that their confidence in their clinical skills related to this procedure increased owing to the process of training for the DBC. Conclusions: The OSATS yielded more detailed evaluations of anastomosis skill with a lower variability compared with the instructor's impression-based evaluation in this web-based training. Real-time evaluation methods, such as the ice-skating method, have proven to be valuable tools for the standardized assessment of web-based surgical education.

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Malignant lymphoma after liver transplantation for liver cirrhosis caused by human immunodeficiency virus and hepatitis C virus co-infection

Hasegawa Y., Obara H., Kikuchi T., Uno S., Tsujikawa H., Yamada Y., Hori S., Eguchi S., Kitagawa Y.

Journal of Infection and Chemotherapy 29 ( 12 ) 1160 - 1163 2023.12

ISSN 1341321X

Here, we describe a rare case of malignant lymphoma after liver transplantation for liver cirrhosis caused by human immunodeficiency virus (HIV) and hepatitis C virus (HCV) co-infection. A male patient was diagnosed with hemophilia A at 8 months of age. Since then, he had been receiving blood products, which led to HIV and HCV co‐infection. His HIV viral load was suppressed with antiretroviral therapy, and a sustained virologic response was achieved for HCV using direct-acting antivirals. However, his decompensated liver cirrhosis progressed, and deceased donor liver transplantation was performed. A post-transplant lymphoproliferative disorder (PTLD) developed 105 days after liver transplantation, with enlarged para-aortic and hilar lymph nodes, a right renal mass, and masses in the small and large intestines. Histopathological examination confirmed monomorphic PTLD (diffuse large B-cell lymphoma). Against the treatment (reduction of immunosuppression, rituximab, and chemotherapy), the response was poor, and the patient died 94 days after the outbreak of PTLD. Both transplantation and HIV infection are risk factors for lymphoproliferative diseases. To the best of our knowledge, this is one of the very few reports of PTLD in a patient with HIV/HCV co-infection.

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Comparison of Aortobifemoral Bypass and Endovascular Treatment for Chronic Infrarenal Abdominal Aortic Occlusion From the CHAOS (CHronic Abdominal Aortic Occlusion, ASian Multicenter) Registry

Fujimura N., Takahara M., Obara H., Ichihashi S., George R.K., Igari K., Banno H., Hozawa K., Yamaoka T., Kian C.J., Tan J.W.H., Park K., Skyi P.Y.C., Kato T., Kawarada O.

Journal of Endovascular Therapy 30 ( 6 ) 828 - 837 2023.12

ISSN 15266028

Purpose: To directly compare the clinical outcomes of aortobifemoral bypass surgery (ABF) and endovascular treatment (EVT) for chronic total occlusion (CTO) of the infrarenal abdominal aorta (IAA). Materials and Methods: In this retrospective, multicenter study, we used an international database of 436 patients who underwent revascularization for CTO of the IAA between 2007 and 2017 at 30 Asian cardiovascular centers. After excluding 52 patients who underwent axillobifemoral bypass surgery, 384 patients (139 ABFs and 245 EVTs) were included in the analysis. Propensity score-matched analysis was performed to compare clinical results in the periprocedural period and the long-term. Results: Propensity score matching extracted 88 pairs. Procedure time (ABF; 288 [240–345] minutes vs EVT; 159 [100–205] minutes, p<0.001) and length of hospital stay (17 [12–23] days vs 5 [4–13] days, p<0.001) were significantly shorter in the EVT group than in the ABF group, while the proportions of procedural success (98.9% versus 96.6%, p=0.620), complications (9.1% versus 12.3%, p=0.550), and mortality (2.3% versus 3.8%, p=1.000) were not different between the groups. At 1 months, ABI significantly increased more in the ABF group for both in a limb with the lower (0.56 versus 0.50, p=0.018) and the higher (0.49 versus 0.34, p=0.001) baseline ABI, while the change of the Rutherford category was not significantly different between the groups (p=0.590). At 5 years, compared with the EVT group, the ABF group had significantly better primary patency (89.4±4.3% versus 74.8±4.3%, p=0.035) and survival rates (86.9±4.5% versus 66.2±7.5%, p=0.007). However, there was no significant difference between the groups for secondary patency (100.0%±0.0% versus 93.5%±3.9%, p=0.160) and freedom from target lesion revascularization (TLR) (89.3±4.3% vs 77.3±7.3%, p=0.096). Conclusion: Even with recent advancements in EVT, primary patency was still significantly better for ABF in CTO of the IAA. However, there was no difference between the groups in terms of secondary patency and freedom from TLR at 5 years. Furthermore, there was no difference in procedural success, complications, mortality, and improvement in the Rutherford classification during the periprocedural period, with significantly shorter procedure time and hospital stay in the EVT group.

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Delayed-Onset Organ/Space Surgical Site Infection Worsens Prognosis in High-Risk Stage II and III Colorectal Cancer

Okui J., Shigeta K., Kato Y., Mizuno S., Sugiura K., Seo Y., Nakadai J., Baba H., Kikuchi H., Hirata A., Makino A., Kondo T., Matsui S., Seishima R., Okabayashi K., Obara H., Sato Y., Kitagawa Y.

Journal of Gastrointestinal Surgery 27 ( 11 ) 2515 - 2525 2023.11

ISSN 1091255X

Background: It is unclear how early- and delayed-onset organ/space surgical site infections (SSIs) affect the long-term prognosis of patients with colorectal cancer, who are potential candidates for adjuvant chemotherapy. This study aimed to investigate the association between the timing of SSI onset and clinical outcome. Methods: This retrospective, multicenter cohort study evaluated patients who were diagnosed with high-risk stage II or III colorectal cancer and underwent elective surgery between 2010 and 2020. Five-year recurrence-free survival (RFS) was the primary endpoint and was compared between early SSI, delayed SSI (divided based on the median date of SSI onset), and non-SSI groups. Results: A total of 2,065 patients were included. Organ/space SSI was diagnosed in 91 patients (4.4%), with a median onset of 6 days after surgery. The early-onset SSI group had a higher proportion of patients with Clavien–Dindo grade ≥IIIb SSI than the delayed-onset SSI. Patients who received adjuvant chemotherapy (AC) had earlier organ/space SSI onset than those who did not. The adjusted hazard ratio of 5-year RFS in the delayed-onset SSI was 2.58 (95% confidence interval: 1.43–4.65; p = 0.002): higher than that in the early-onset SSI, with the non-SSI as the reference. Conclusions: Delayed-onset organ/space SSI worsened long-term prognosis compared to early-onset, and this may be due to delayed initiation of AC. Patients who are clinically suspected of having lymph node metastasis might need additional intervention to prevent delays in commencing AC due to the delayed SSI.

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Risk Assessment of Liver Transplantation After Kasai Portoenterostomy in Children and Adults

Udagawa D., Hasegawa Y., Obara H., Yamada Y., Shinoda M., Kitago M., Abe Y., Kuroda T., Kitagawa Y.

Journal of Surgical Research 290 109 - 115 2023.10

ISSN 00224804

Introduction: Reports of liver transplantation (LT) after Kasai portoenterostomy (KPE) in adult patients with biliary atresia are scarce. The aim of this study was to evaluate the outcomes and investigate the risk factors of LT after KPE in both pediatric and adult patients. Methods: We retrospectively reviewed a prospective database of patients with biliary atresia who underwent LT after KPE. Eighty-nine consecutive patients were included, and risk factors for in-hospital mortality after LT were assessed. Results: The median age of the patients was 2 y (range, 0-45 y). Forty-six patients (51.7%) had a history of upper abdominal surgery after KPE. The in-hospital mortality rate was 5.6% (5 patients). Of these, 80% of patients with mortality were aged ≥17 y, and all patients with mortality had a history of two or more upper abdominal surgeries. In the univariate and receiver operating characteristic curve analyses, age ≥17 y and the number of previous upper abdominal surgeries ≥2 were identified as possible risk factors. Conclusions: Our study suggests that older age and multiple previous upper abdominal surgeries are important risk factors for mortality after LT following KPE. We believe that these findings will serve as indications for safe LT in future patients.

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Long-term outcomes following ABO-incompatible living donor liver transplantation for acute liver failure: a single-center experience of over 20 years

Hirukawa K., Shinoda M., Hasegawa Y., Obara H., Kitago M., Yagi H., Abe Y., Yamada Y., Tanabe M., Kitagawa Y.

Surgery Today 53 ( 10 ) 1160 - 1172 2023.10

ISSN 09411291

Purpose: Acute liver failure is a life-threatening condition for which ABO-incompatible living donor liver transplantation (ABOi-LDLT) is sometimes the only life-saving treatment option. We reviewed a single-center experience of adult ABOi-LDLT treatment for acute liver failure (ALF). Methods: Preoperative treatment, immune indices (B cell marker, anti-donor blood-type antibody), and postoperative outcomes were compared between ALF and non-ALF groups. Results: There were 5 and 33 patients in the ALF and non-ALF groups, respectively. The ALF group received higher doses of steroids, underwent more rounds of plasma exchange (PE), and underwent transplantation for ALF with a shorter interval following preoperative rituximab (RTx) administration (median: 2 vs 13 days; P < 0.05) than the non-ALF group. Preoperatively, CD19-positive lymphocytes in the peripheral blood were sufficiently depleted in all of the non-ALF group patients, whereas they were poorly depleted in the ALF group. Postoperatively, neither group suffered anti-donor blood-type antibody titer rebound or antibody-mediated rejection. The ALF group had a comparable 5-year survival rate to the non-ALF group (80.0% vs 77.9%). Conclusions: Despite the delayed preoperative administration of RTx, the ALF group showed an uneventful immunological response and acceptable long-term survival rate. Thus, ABOi-LDLT seems a viable treatment option for ALF.

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