The Experts below are selected from a list of 22113 Experts worldwide ranked by ideXlab platform

Yukihiko Nosé - One of the best experts on this subject based on the ideXlab platform.

  • development of rotary Blood Pump technology past present and future
    Artificial Organs, 2000
    Co-Authors: Yukihiko Nosé, Masaharu Yoshikawa, S Murabayashi, T Takano
    Abstract:

    Even though clinical acceptance of a nonpulsatile Blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile Blood Pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher Blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary Blood Pumps, including a 2-day rotary Blood Pump for cardiopulmonary bypass application, a 2 week Pump for ECMO and short-term circulatory assistance, a 2 year Pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day Pump (the Nikkiso-Fairway cardiopulmonary bypass Pump) in 4 years (1989-1993), a 2 week Pump (Kyocera gyro G1E3 Pump) in 6 years (1992-1998), and a bridge to transplant Pump (DeBakey LVAD-an axial flow Blood Pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal Blood Pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.

  • Design and development strategy for the rotary Blood Pump.
    Artificial Organs, 1998
    Co-Authors: Yukihiko Nosé
    Abstract:

    Development of an antitraumatic antithrombogenic and durable Blood Pump is a very difficult task. Based upon this author's experience of over 35 years in the development of various types of cardiac prostheses, development strategies for a rotary Blood Pump are described. A step-by-step development strategy is thus proposed. Initially, the development of a 2 day antitraumatic Pump (Phase 1) would be made. Then, conversion of this Pump to a 2 week antithrombogenic Pump (Phase 2) should be attempted. After the successful development of the Phase 2 Pump, the conversion of this device to a durable, implantable, and long-term Blood Pump (Phase 3) should be established. Based upon this development strategy, 2 rotary Blood Pumps, namely, the axial flow Blood Pump and the centrifugal Blood Pump, have been developed in less than 6 years with modest development costs.

  • Development of a non-pulsatile permanent rotary Blood Pump.
    European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, 1997
    Co-Authors: Yukihiko Nosé, K Kawahito
    Abstract:

    For many years, a common belief was that non-pulsatile perfusion produced physiological and circulatory abnormalities. Since 1977 our group has reported, if a 20% higher Blood flow was used more than required for a pulsatile Blood Pump, there would be no circulatory or physiological abnormalities. These experimental findings confirmed that there was no difference in clinical outcome when using a pulsatile or non-pulsatile Blood Pump. Furthermore, the non-pulsatile rotary Blood Pump has demonstrated efficient and reliable performance in various clinical situations. The non-pulsatile Blood Pump is a simple and reliable design, that can be easily manufactured, and has the following desirable features. There is no need to incorporate heart valves, a large orifice inflow conduit, or a compliance volume-shifting chamber. Since an electrical motor operates continuously, the on-and-off motion required for a pulsatile Pump is not necessary; therefore, it becomes a more efficient and durable system. Further, the control algorism is simpler and more reliable than a pulsatile Pump. Considering these factors, the non-pulsatile Blood Pump can be selected for a permanently implantable assist device. To develop an implantable non-pulsatile cardiac device, it is necessary to incorporate seven features in the system such as: small size, atraumatic features, anti-thrombogenic features, anti-infection features, durable and simple design, and low energy requirement with easy controllability.

  • Can We Develop a Nonpulsatile Permanent Rotary Blood Pump? Yes, We Can.
    Artificial Organs, 1996
    Co-Authors: Yukihiko Nosé, K Kawahito, Tadashi Nakazawa
    Abstract:

    For many years, it was thought that nonpulsatile perfusion produced physiological and circulatory abnormalities. Since 1977, Yukihiko Nose and his colleagues have challenged this misconception. Toward that end, they did show that if a 20% higher Blood flow uses more than that required for a pulsatile Blood Pump, then there would be no circulatory or physiological abnormalities. These experimental findings confirm that there is no difference in clinical outcome using either a pulsatile or nonpulsatile Blood Pump. Furthermore, the nonpulsatile rotary Blood Pump demonstrates efficient and reliable performance in various clinical situations. The nonpulsatile Blood Pump is a simple and reliable design that is manufactured easily and that has several desirable features. There is no need to incorporate heart valves, which are the most thrombogenic and Blood trauma-inducing component. A continuous flow Pump does not require a large orifice inflow conduit and proves to be easier to implant in patients with minimal damage to the myocardium. There is no need to incorporate a compliance volume-shifting device, which is essential for a pulsatile Blood Pump. The nonpulsatile device is a continuous Blood Pumping system; therefore, the control system is simpler and more reliable than that of a pulsatile Pump. Because of the rotary Blood Pump's structure, only one moving part is necessary for the Blood-Pumping motion. By using durable components for this moving part, a durable system becomes possible. Because the electrical motor operates continuously, the on-and-off motion required for a pulsatile Pump is not necessary; therefore, it is a more efficient and durable system. Thus, this group is working on the development of a nonpulsatile Blood Pump as a permanently implantable assist device. To achieve this goal, it is necessary to incorporate seven features into the system: small size, atraumatic features, antithrombogenic features, antiinfection features, a simple and durable design, and low energy requirement with easy controllability.

T Takano - One of the best experts on this subject based on the ideXlab platform.

  • development of rotary Blood Pump technology past present and future
    Artificial Organs, 2000
    Co-Authors: Yukihiko Nosé, Masaharu Yoshikawa, S Murabayashi, T Takano
    Abstract:

    Even though clinical acceptance of a nonpulsatile Blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile Blood Pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher Blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary Blood Pumps, including a 2-day rotary Blood Pump for cardiopulmonary bypass application, a 2 week Pump for ECMO and short-term circulatory assistance, a 2 year Pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day Pump (the Nikkiso-Fairway cardiopulmonary bypass Pump) in 4 years (1989-1993), a 2 week Pump (Kyocera gyro G1E3 Pump) in 6 years (1992-1998), and a bridge to transplant Pump (DeBakey LVAD-an axial flow Blood Pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal Blood Pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.

  • an emergency balloon occlusion system for a rotary Blood Pump left ventricular assist system
    Artificial Organs, 1999
    Co-Authors: Goro Ohtsuka, Kin-ichi Nakata, Masaharu Yoshikawa, T Takano, Akinori Sueoka, Koshiro Saito, Akira Igarashi, Eiki Tayama, Julia Glueck, H Koyanagi
    Abstract:

    A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary Blood Pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute Pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary Blood Pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail-safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the Pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary Blood Pump LVAS.

Yohji Okada - One of the best experts on this subject based on the ideXlab platform.

  • axial type self bearing motor for axial flow Blood Pump
    Artificial Organs, 2003
    Co-Authors: Yohji Okada, Toru Masuzawa, Takashi Yamane, Kenichi Matsuda, Kunihiro Ohmori, Yoshiaki Konishi, Shinya Fukahori, Satoshi Ueno, Seungjong Kim
    Abstract:

    An axial self-bearing motor is proposed which can drive an axial Blood Pump without physical contact. It is a functional combination of the bi-directional disc motor and the axial active magnetic bearing, where it actively controls single degree-of-freedom motion, while other motions such as lateral vibration are passively stable. For application to a Blood Pump, the proposed self-bearing motor has the advantages of simple structure and small size. Through the finite element method (FEM) analysis and the experimental test, its good feasibility is verified. Finally, the axial flow Pump is fabricated using the developed magnetically suspended motor. The Pump test is carried out and the results are discussed in detail.

  • magnetically suspended centrifugal Blood Pump with an axially levitated motor
    Artificial Organs, 2003
    Co-Authors: Toru Masuzawa, Shiroh Ezoe, Tsuyoshi Kato, Yohji Okada
    Abstract:

    The longevity of a rotary Blood Pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal Blood Pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and Pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The Pump shows promise as a ventricular assist device.

  • Magnetically suspended centrifugal Blood Pump with a self bearing motor.
    Asaio Journal, 2001
    Co-Authors: Toru Masuzawa, Hiroyuki Onuma, Yohji Okada
    Abstract:

    A magnetically suspended centrifugal Blood Pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semi-opened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar Pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal Blood Pump is a candidate for an implantable left ventricular assist device.

Masaharu Yoshikawa - One of the best experts on this subject based on the ideXlab platform.

  • development of rotary Blood Pump technology past present and future
    Artificial Organs, 2000
    Co-Authors: Yukihiko Nosé, Masaharu Yoshikawa, S Murabayashi, T Takano
    Abstract:

    Even though clinical acceptance of a nonpulsatile Blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile Blood Pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher Blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary Blood Pumps, including a 2-day rotary Blood Pump for cardiopulmonary bypass application, a 2 week Pump for ECMO and short-term circulatory assistance, a 2 year Pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day Pump (the Nikkiso-Fairway cardiopulmonary bypass Pump) in 4 years (1989-1993), a 2 week Pump (Kyocera gyro G1E3 Pump) in 6 years (1992-1998), and a bridge to transplant Pump (DeBakey LVAD-an axial flow Blood Pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal Blood Pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.

  • an emergency balloon occlusion system for a rotary Blood Pump left ventricular assist system
    Artificial Organs, 1999
    Co-Authors: Goro Ohtsuka, Kin-ichi Nakata, Masaharu Yoshikawa, T Takano, Akinori Sueoka, Koshiro Saito, Akira Igarashi, Eiki Tayama, Julia Glueck, H Koyanagi
    Abstract:

    A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary Blood Pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute Pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary Blood Pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail-safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the Pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary Blood Pump LVAS.

Toru Masuzawa - One of the best experts on this subject based on the ideXlab platform.

  • axial type self bearing motor for axial flow Blood Pump
    Artificial Organs, 2003
    Co-Authors: Yohji Okada, Toru Masuzawa, Takashi Yamane, Kenichi Matsuda, Kunihiro Ohmori, Yoshiaki Konishi, Shinya Fukahori, Satoshi Ueno, Seungjong Kim
    Abstract:

    An axial self-bearing motor is proposed which can drive an axial Blood Pump without physical contact. It is a functional combination of the bi-directional disc motor and the axial active magnetic bearing, where it actively controls single degree-of-freedom motion, while other motions such as lateral vibration are passively stable. For application to a Blood Pump, the proposed self-bearing motor has the advantages of simple structure and small size. Through the finite element method (FEM) analysis and the experimental test, its good feasibility is verified. Finally, the axial flow Pump is fabricated using the developed magnetically suspended motor. The Pump test is carried out and the results are discussed in detail.

  • magnetically suspended centrifugal Blood Pump with an axially levitated motor
    Artificial Organs, 2003
    Co-Authors: Toru Masuzawa, Shiroh Ezoe, Tsuyoshi Kato, Yohji Okada
    Abstract:

    The longevity of a rotary Blood Pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal Blood Pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and Pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The Pump shows promise as a ventricular assist device.

  • Magnetically suspended centrifugal Blood Pump with a self bearing motor.
    Asaio Journal, 2001
    Co-Authors: Toru Masuzawa, Hiroyuki Onuma, Yohji Okada
    Abstract:

    A magnetically suspended centrifugal Blood Pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semi-opened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar Pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal Blood Pump is a candidate for an implantable left ventricular assist device.

  • development of design methods for a centrifugal Blood Pump with a fluid dynamic approach results in hemolysis tests
    Artificial Organs, 1999
    Co-Authors: Toru Masuzawa, H. Takano, Eisuke Tatsumi, Yoshiyuki Taenaka, Tomonori Tsukiya, Takashi Yamane, Masahiro Nishida, Seiko Endo, Balazs Asztalos, Yuki Miyazoe
    Abstract:

    : The purpose of this study was to examine the relationship between local flow conditions and the hemolysis level by integrating hemolysis tests, flow visualization, and computational fluid dynamics to establish practical design criteria for centrifugal Blood Pumps with lower levels of hemolysis. The Nikkiso centrifugal Blood Pump was used as a standard model, and Pumps with different values of 3 geometrical parameters were tested. The studied parameters were the radial gap between the outer edge of the impeller vane and the casing wall, the position of the outlet port, and the discharge angle of the impeller vane. The effect of a narrow radial gap on hemolysis was consistent with no evidence that the outlet port position or the vane discharge angle affected Blood trauma in so far as the Nikkiso centrifugal Blood Pump was concerned. The radial gap should be considered as a design parameter of a centrifugal Blood Pump to reduce Blood trauma.