The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Hitoshi Yaku - One of the best experts on this subject based on the ideXlab platform.
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development of a completely autologous Valved Conduit with the sinus of valsalva using in body tissue architecture technology a pilot study in pulmonary valve replacement in a beagle model
Circulation, 2010Co-Authors: Masashi Yamanami, Keiichi Kanda, Taiji Watanabe, Hatsue Ishibashiueda, Tsutomu Tajikawa, Kenkichi Ohba, Yuki Yahata, Masami Uechi, Megumi Fujiwara, Hitoshi YakuAbstract:Background—We developed autologous prosthetic implants by simple and safe in-body tissue architecture technology. We present the first report on the development of autologous Valved Conduit with the sinus of Valsalva (BIOVALVE) by using this unique technology and its subsequent implantation in the pulmonary valves in a beagle model. Methods and Results—A mold of BIOVALVE organization was assembled using 2 types of specially designed silicone rods with a small aperture in a trileaflet shape between them. The concave rods had 3 projections that resembled the protrusions of the sinus of Valsalva. The molds were placed in the dorsal subcutaneous spaces of beagle dogs for 4 weeks. The molds were covered with autologous connective tissues. BIOVALVEs with 3 leaflets in the inner side of the Conduit with the sinus of Valsalva were obtained after removing the molds. These valves had adequate burst strength, similar to that of native valves. Tight valvular coaptation and sufficient open orifice area were observed i...
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preparation of in vivo tissue engineered Valved Conduit with the sinus of valsalva type iv biovalve
Journal of Artificial Organs, 2010Co-Authors: Masashi Yamanami, Keiichi Kanda, Taiji Watanabe, Tsutomu Tajikawa, Kenkichi Ohba, Hitoshi Yaku, Yuki Yahata, Yasuhide NakayamaAbstract:A novel autologous Valved Conduit with the sinus of Valsalva—defined as a type IV biovalve—was created in rabbits by “in-body tissue-architecture” technology with a specially designed mold for the valve leaflets and the sinus of Valsalva and a microporous tubular scaffold for the Conduit. The mold included 2 rods composed of silicone substrates. One was concave shaped, with 3 projections resembling the sinus of Valsalva; the other was convex shaped. The connection between the rods was designed to resemble the closed form of a trileaflet valve. The 2 rods were connected with a small aperture of 500–800 μm, which bound membranous connective tissue obtained from the dorsal subcutaneous layer of a rabbit. The rods were placed in a polyurethane scaffold that had many windows in its center. Both ends of the scaffold were tied with thread for fixation, and this assembly was embedded for 1 month in a subcutaneous pouch in the same Japanese white rabbit from which the connective tissue was obtained. After 1 month, all the surfaces of the implant were found to be completely covered with newly developed connective tissue. The substrates were removed from both sides of the harvested cylindrical implant, and homogenous well-balanced trileaflet-shaped membranous tissue was found inside the developed Conduit with 3 protrusions resembling the sinus of Valsalva. The trileaflet valve closed and opened rapidly in synchrony with the backward and forward flow of a pulsatile flow circuit in vitro.
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in vivo tissue engineered Valved Conduit with designed molds and laser processed scaffold
Journal of Cardiovascular Nursing, 2008Co-Authors: Kyoko Hayashida, Keiichi Kanda, Yosihiro Okamoto, Osamu Sakai, Taiji Watanabe, Hatsue Ishibashiueda, Masaaki Onoyama, Tsutomu Tajikawa, Kenkichi Ohba, Hitoshi YakuAbstract:BACKGROUND: In body tissue architecture" technology is a practical concept of regenerative medicine that uses the living recipient body's reaction to a foreign object as a reactor for autologous tissue organization. A novel autologous Valved Conduit was produced by creating a specially designed Conduit-mold composite and elastomeric scaffold for this unique in vivo tissue engineering. METHODS: Convex and concave plastic molds assembled with a small aperture of 500-800 microm were inserted into a microporous elastomeric Conduit scaffold. The assembly was placed in a subcutaneous pocket of Japanese white rabbits for 1 month. The molds were pulled out from the edge of the harvested implant to obtain the Valved Conduit. RESULTS: Homogenous and well-balanced trileaflet of membranous tissue was developed in the optimized aperture of molds. The valve leaflet closed and opened rapidly in synchronization with the backward and forward flow of the pulsatile flow circuit in vitro. CONCLUSIONS: A tissue-engineered Conduit incorporated with a functional autologous trileaflet valve was developed in an in vivo reactor by optimizing the microstructures of Conduit scaffolds and newly designing the composite molds. The method holds promise for a safe, biocompatible, and economical heart valve prosthesis.
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expanded polytetrafluoroethylene Valved Conduit and patch with bulging sinuses in right ventricular outflow tract reconstruction
The Journal of Thoracic and Cardiovascular Surgery, 2007Co-Authors: Takako Miyazaki, Kouji Fukae, Hitoshi Yaku, Masaaki Yamagishi, Atsuhiro Nakashima, Toshihide Nakano, Hideaki KadoAbstract:Objectives No specific prosthetic material is currently recognized as being the most suitable for right ventricular outflow tract reconstruction for congenital heart defects. Prosthetic valves are subject to wear and stress because they do not create vortex flow, which helps natural valves to close. We designed a fan-shaped expanded polytetrafluoroethylene Valved Conduit and patch with bulging sinuses that create vortex flow, making them more reliable over the long term. Methods Bulging sinuses were formed on a sheet of expanded polytetrafluoroethylene using a specially designed mold. Fan-shaped expanded polytetrafluoroethylene sheets (0.1 mm thick) were anastomosed to the edge of the bulging sinuses as valve leaflets, creating monocuspid, bicuspid, or tricuspid valves. These valves were implanted in 157 patients undergoing right ventricular outflow tract reconstruction (age 16 days to 45.4 years, median 2.0 years), in 48 patients as a Conduit, and in 109 patients as a patch. Valve function was followed up by echocardiography for 5.6 to 63.7 months (mean 20.8 months). Results There was no mortality or morbidity, and no patients required reoperation during follow-up. No patients had stenosis, and regurgitation was less than mild in all patients with Conduits and moderate in 15 patients (13.8%) with patches, but moderate regurgitation did not further develop during follow-up. Valve motion was fully maintained in all patients. Conclusions The expanded polytetrafluoroethylene Valved Conduits and patches with bulging sinuses showed excellent early-to-midterm results. The Valved Conduits and patches seem to be promising alternatives to homografts in right ventricular outflow tract reconstruction. Their function will be followed up further.
Wei-ling Chen - One of the best experts on this subject based on the ideXlab platform.
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in vitro hemodynamic evaluation of right ventricle pulmonary artery continuity reconstruction through a trileaflet expanded polytetrafluoroethylene Valved Conduit
International Conference of the IEEE Engineering in Medicine and Biology Society, 2018Co-Authors: Wei-ling ChenAbstract:Percutaneous pulmonary valve implantation is a technique to treat narrowed pulmonary valves or leaky pulmonary valves in congenital heart disease. This technique provides a promising strategy to reduce surgical risk. In clinical cases, due to stent size restrictions, commercial valve stents are sometimes unsuitable for children or certain patients. Hence, handmade pulmonary Valved Conduits prove useful because a customized size can be obtained for valve replacement. We propose a meta-learning-based intelligent model to train an estimator (including two sub-estimators) to determine optimal trileaflet parameters for customized trileaflet valve reconstruction. The purpose of this study was to investigate the hemodynamic and functional consequences of the novel design by employing a mock circulation system. We recorded the diastolic valve leakage and calculated the pulmonary regurgitation, regurgitation fraction, and ejection efficiency in a pulsatile setting. The prosthetic leaflet behavior was assessed using an endoscope camera and the pressure drops through valves were measured. All the in vitro parameters indicated that the expanded polytetrafluoroethylene (ePTFE) Valved Conduits were not inferior to commercial mechanical or tissue valve Conduits and could decrease the regurgitation volume and increase the efficiency. Compatible early clinical outcomes were also identified between ePTFE Valved Conduits and other Valved Conduits used for right ventricular outflow tract reconstruction. The ePTFE Valved Conduits could be implanted in relatively small patients. An in vitro experimental study provided evidence that a handmade ePTFE Valved Conduit could be an attractive alternative to other commercialized Valved Conduits used for right ventricle-pulmonary artery continuity reconstruction.
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In Vitro Hemodynamic Evaluation of Right Ventricle–Pulmonary Artery Continuity Reconstruction Through a Trileaflet Expanded Polytetrafluoroethylene Valved Conduit
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2018Co-Authors: Wei-ling ChenAbstract:Percutaneous pulmonary valve implantation is a technique to treat narrowed pulmonary valves or leaky pulmonary valves in congenital heart disease. This technique provides a promising strategy to reduce surgical risk. In clinical cases, due to stent size restrictions, commercial valve stents are sometimes unsuitable for children or certain patients. Hence, handmade pulmonary Valved Conduits prove useful because a customized size can be obtained for valve replacement. We propose a meta-learning-based intelligent model to train an estimator (including two sub-estimators) to determine optimal trileaflet parameters for customized trileaflet valve reconstruction. The purpose of this study was to investigate the hemodynamic and functional consequences of the novel design by employing a mock circulation system. We recorded the diastolic valve leakage and calculated the pulmonary regurgitation, regurgitation fraction, and ejection efficiency in a pulsatile setting. The prosthetic leaflet behavior was assessed using an endoscope camera and the pressure drops through valves were measured. All the in vitro parameters indicated that the expanded polytetrafluoroethylene (ePTFE) Valved Conduits were not inferior to commercial mechanical or tissue valve Conduits and could decrease the regurgitation volume and increase the efficiency. Compatible early clinical outcomes were also identified between ePTFE Valved Conduits and other Valved Conduits used for right ventricular outflow tract reconstruction. The ePTFE Valved Conduits could be implanted in relatively small patients. An in vitro experimental study provided evidence that a handmade ePTFE Valved Conduit could be an attractive alternative to other commercialized Valved Conduits used for right ventricle-pulmonary artery continuity reconstruction.
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In Vitro Evaluation of Hemodynamic Performance for Right Ventricular Outflow Tract Reconstruction with Trileaflet ePTFE Valved Conduit
IFMBE Proceedings, 2018Co-Authors: Wei-ling Chen, Chiu Chin WuAbstract:Right ventricle to pulmonary artery (RV-PA) continuity reconstruction traditionally is treaded by open repair with pulmonary valve implantation or replacement. Percutaneous pulmonary valve implantation (PPVI) has evolved as most exciting development surgical strategy with dysfunctional right ventricle-pulmonary artery Conduits. However, size restrictions of the currently available valves for PPVI application prevents development in a larger pool of patients. We propose a formula for designing handmade trileaflet-Valved Conduits with different diameters. The formula is derived from a trigonometric function and can be used to estimate the optimal parameters for ePTFE-Valved Conduits for young adults and children. The purpose of this study is to investigate the hemodynamic and functional consequences of the new design using a mock circulation system. We recorded the diastolic valve leakage and calculated pulmonary regurgitation, regurgitation fraction, and ejection efficiency in pulsatile setting. Additionally, the prosthetic leaflet behavior was assessed with an endoscope camera and the pressure drops through valves were measured. All the in vitro parameters indicated that the ePTFE-Valved Conduits did not have an inferior outcome compared with commercial mechanical or tissue valve Conduits and could decrease the regurgitation volume and increase the efficiency. Compatible early clinical outcomes were also found among ePTFE-Valved Conduits and other Valved Conduits used for RVOT reconstruction, and ePTFE-Valved Conduits could be implanted in patients of a significantly smaller size. In vitro experimental study provided evidence that a handmade ePTFE-Valved Conduit could be an attractive alternative to other commercialized Valved Conduits used for surgical Right ventricle to pulmonary artery (RV-PA) continuity reconstruction.
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Customized Handmade Pulmonary Valved Conduit Reconstruction for Children and Adult Patients Using Meta-Learning Based Intelligent Model
IEEE Access, 2018Co-Authors: Wei-ling Chen, Jieh-neng Wang, Pong-jeu Lu, Ming-yao Chan, Jui-te WuAbstract:Percutaneous pulmonary valve implantation is an improved technique that is used to treat narrowed pulmonary valves or leaky pulmonary valves in patients with congenital heart disease. This technique represents a promising strategy to reduce surgical risk and operation. In clinical cases, commercial valve stents are sometimes not available for children or special subjects due to restrictions in stent size. Hence, the handmade pulmonary Valved Conduit provides a strategy to design stents with customized size for valve replacement. In this paper, we propose a meta-learning-based intelligent model to train an estimator (including two sub-estimators) to determine optimal trileaflet parameters for customized trileaflet valve reconstruction. This estimation model overcomes the problem of empirical parameter determination. The meta-learning model possesses learning-to-optimization capability for training generalized regression neural network by particle swarm optimization algorithm. Through incremental training patterns, this scheme can gradually enhance optimization to provide refined parameters for customized designs that can be applicable to individuals of all age groups. The customized handmade pulmonary Valved Conduit was validated by assessing the regurgitation fraction and the heart pump efficiency using an experimental cardiopulmonary circulation loop system.
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Handmade Trileaflet Valve Design and Validation for Pulmonary Valved Conduit Reconstruction Using Taguchi Method and Cascade Correlation Machine Learning Model
IEEE Access, 2018Co-Authors: Chung-dann Kan, Wei-ling Chen, Jieh-neng Wang, Pong-jeu Lu, Ming-yao Chan, Chia-hung Lin, Jui-te WuAbstract:Pulmonary valve diseases in children and adults include different degrees of stenosis, regurgitation, or congenital defects. Valve repair or replacement surgery is used to treat valvular dysfunction and to improve regurgitations flow for pulmonary valve pathologies. Handmade trileaflet valve designs with different ranges of diameters have been used for pulmonary Valved Conduit reconstruction among children or adult patients with available conditions. In this paper, we propose a multiple regression model as a cascadecorrelation-network-based estimator to determine optimal trileaflet parameters, including width, length, and upper/lower curved structures, for trileaflet valve reconstruction. The diameter of the main pulmonary artery is determined via computed tomography pulmonary angiography, and a trileaflet valve template is rapidly sketched. The actual valve is constructed using an expanded polytetrafluoroethylene material. Using an experimental pulmonary circulation loop system, design parameters and valve efficacy can be validated by the Taguchi method through calculation of signal-to-noise ratios. Experimental results indicate that in contrast to commercial valve stents, the handmade trileaflet valve exhibits good performance and is a valuable option in treatment of severe pulmonary regurgitation.
Si Chan Sung - One of the best experts on this subject based on the ideXlab platform.
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simplified tricuspid polytetrafluoroethylene Valved Conduit midterm results of multicenter study
The Annals of Thoracic Surgery, 2019Co-Authors: Kwang Ho Choi, Si Chan Sung, Hoon Ko, Joung Hee Byun, Han Ki Park, Yu Rim ShinAbstract:Background Conduit survival without significant dysfunction is important when selecting the right ventricular outflow tract Conduit. We made an expanded polytetrafluoroethylene tricuspid Valved Conduit using a simplified technique. We aimed to investigate the midterm functional results and longevity of this Conduit. Methods Between November 2008 and December 2016, four hospitals in Korea implanted 145 Valved Conduits. We retrospectively analyzed their functional results and longevity. Results The patients' median age at operation was 36.6 months; the median body weight was 11.3 kg. The mean follow-up duration was 32.3 ± 24.5 months. There were four inhospital deaths and three late deaths, but there were no Conduit-related deaths. The mean peak systolic pressure gradient across the Conduit was 14.7 ± 8.3 mm Hg and 31.6 ± 17.7 mm Hg at discharge and last follow-up, respectively. Six patients (4.4%) had moderate or more Conduit valve regurgitation at last follow-up. Conduit dysfunction was observed in 30 patients (21.9%), mainly caused by increased pressure gradient (24 of 30, 80%). Freedom from Conduit dysfunction was 88.1% and 58.5% at 3 and 5 years, respectively. Lower freedom from Conduit dysfunction was observed in small Conduits. Eleven patients (7.8%) underwent Conduit explantation, and freedom from explantation was 94.8% and 81.7% at 3 and 5 years, respectively. The main cause of explantation was Conduit stenosis. Small Conduits tended to have lower freedom from explantation. Conclusions Functional results and longevity of our expanded polytetrafluoroethylene tricuspid Valved Conduit are acceptable. Although our Conduits tend to have increasing pressure gradient over time, especially in small Conduits, they have low incidence of moderate or more regurgitation.
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late results of right ventricular outflow tract reconstruction with a bicuspid expanded polytetrafluoroethylene Valved Conduit
Journal of Cardiac Surgery, 2018Co-Authors: Kwang Ho Choi, Si Chan Sung, Hoon KoAbstract:BACKGROUND AND AIM TO READ: We report the results of a bicuspid expanded polytetrafluoroethylene (ePTFE) Valved Conduit used for right ventricular outflow tract reconstruction (RVOTR). METHODS: Between November 2005 and February 2009, 12 Conduits were used for RVOTR. The mean age and weight of patients were 43.5 ± 46.4 months and 13.4 ± 8.6 kg. The main diagnosis was tetralogy of Fallot with pulmonary atresia in eight patients. The most common Conduit size was 18 mm. The mean follow-up was 88.0 ± 35.9 months. RESULTS: There were no operative and late mortalities. At discharge, the mean peak systolic pressure gradient across the RVOT was 14.1 ± 11.3 mmHg. There was no Conduit valve regurgitation in nine patients. At the latest echocardiography (mean follow-up: 84.3 ± 35.5 months), the mean peak systolic pressure gradient across the RVOT was 59.7 ± 20.2 mmHg, and there was no Conduit valve regurgitation in six patients. Freedom from Conduit malfunction was 100% and 83.3%, at 1 and 8 years, respectively. Two Conduits were explanted due to sternal compression and four from Conduit malfunction. Freedom from explantation was 83.3% and 74.2% at 2 and 8 years, respectively. CONCLUSIONS: ePTFE bicuspid Valved Conduit has good late function in terms of valve regurgitation, but the pressure gradient across the Conduit increases with time, which is the main cause of Conduit failure and explantation.
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a new simplified technique for making tricuspid expanded polytetrafluoroethylene Valved Conduit for right ventricular outflow reconstruction
The Annals of Thoracic Surgery, 2013Co-Authors: Si Chan Sung, Yun Hee Chang, Ji Ae ParkAbstract:Several methods of making expanded polytetrafluoroethylene Valved Conduit have been reported, but these techniques are complicated and less reproducible. We have developed a new simplified technique for making a tricuspid expanded polytetrafluoroethylene Valved Conduit for right ventricular outflow tract reconstruction and have been using this Conduit for approximately 3 years with excellent results. Our technique is straightforward and reproducible, and the cusps in the Conduit are durable due to the use of a specialized suturing technique.
Masaaki Yamagishi - One of the best experts on this subject based on the ideXlab platform.
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Expanded polytetrafluoroethylene-Valved Conduit with bulging sinuses for right ventricular outflow tract reconstruction in adults
General Thoracic and Cardiovascular Surgery, 2010Co-Authors: Yosuke Takahashi, Yasushi Tsutsumi, Osamu Monta, Yasuyuki Kato, Keitaro Kohshi, Tomohiko Sakamoto, Hirokazu Ohashi, Takako Miyazaki, Masaaki YamagishiAbstract:Purpose Generally, right ventricular outflow tract reconstruction in adults is performed using homografts or xenograft. However, sufficient graft material is difficult to obtain and has the problems of calcification and structure destruction. We, therefore, evaluated using expanded polytetrafluoroethylene- (ePTFE)-Valved Conduits with bulging sinuses for right ventricular outflow tract reconstruction in adults. Methods Between February 2006 and April 2008, a total of five patients (three men, two women), ages 25–51 years old (mean ± SD, 40 ± 11 years)] underwent right ventricular outflow tract (RVOT) reconstruction in our institution. In three patients, RVOT reconstruction was performed with the Ross procedure; and in all cases, tricuspid ePTFE (Valved Conduits with bulging sinuses were used. The diameter of the Conduit was determined according to the RVOT size. Valve function was followed up using echocardiography after surgery and during the early/mid-term periods of recovery (13 months to 3.0 years). Results No morbidity occurred, and no patient required further surgery during the follow-up period. During these follow-up periods, pulmonary observation revealed that no patients had stenosis; regurgitation was mild in one patient and trivial in four patients. In regard to the tricuspid valve, regurgitation was trivial in four patients and mild in one patient. Conclusion Although long-term follow-up is required to confirm the durability of the ePTFE-Valved Conduit with bulging sinuses, the present results indicate a satisfactory result in patients who undergo RVOT reconstruction, even in adult cases.
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expanded polytetrafluoroethylene Valved Conduit and patch with bulging sinuses in right ventricular outflow tract reconstruction
The Journal of Thoracic and Cardiovascular Surgery, 2007Co-Authors: Takako Miyazaki, Kouji Fukae, Hitoshi Yaku, Masaaki Yamagishi, Atsuhiro Nakashima, Toshihide Nakano, Hideaki KadoAbstract:Objectives No specific prosthetic material is currently recognized as being the most suitable for right ventricular outflow tract reconstruction for congenital heart defects. Prosthetic valves are subject to wear and stress because they do not create vortex flow, which helps natural valves to close. We designed a fan-shaped expanded polytetrafluoroethylene Valved Conduit and patch with bulging sinuses that create vortex flow, making them more reliable over the long term. Methods Bulging sinuses were formed on a sheet of expanded polytetrafluoroethylene using a specially designed mold. Fan-shaped expanded polytetrafluoroethylene sheets (0.1 mm thick) were anastomosed to the edge of the bulging sinuses as valve leaflets, creating monocuspid, bicuspid, or tricuspid valves. These valves were implanted in 157 patients undergoing right ventricular outflow tract reconstruction (age 16 days to 45.4 years, median 2.0 years), in 48 patients as a Conduit, and in 109 patients as a patch. Valve function was followed up by echocardiography for 5.6 to 63.7 months (mean 20.8 months). Results There was no mortality or morbidity, and no patients required reoperation during follow-up. No patients had stenosis, and regurgitation was less than mild in all patients with Conduits and moderate in 15 patients (13.8%) with patches, but moderate regurgitation did not further develop during follow-up. Valve motion was fully maintained in all patients. Conclusions The expanded polytetrafluoroethylene Valved Conduits and patches with bulging sinuses showed excellent early-to-midterm results. The Valved Conduits and patches seem to be promising alternatives to homografts in right ventricular outflow tract reconstruction. Their function will be followed up further.
Ji Ae Park - One of the best experts on this subject based on the ideXlab platform.
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a new simplified technique for making tricuspid expanded polytetrafluoroethylene Valved Conduit for right ventricular outflow reconstruction
The Annals of Thoracic Surgery, 2013Co-Authors: Si Chan Sung, Yun Hee Chang, Ji Ae ParkAbstract:Several methods of making expanded polytetrafluoroethylene Valved Conduit have been reported, but these techniques are complicated and less reproducible. We have developed a new simplified technique for making a tricuspid expanded polytetrafluoroethylene Valved Conduit for right ventricular outflow tract reconstruction and have been using this Conduit for approximately 3 years with excellent results. Our technique is straightforward and reproducible, and the cusps in the Conduit are durable due to the use of a specialized suturing technique.
