Mechanical circulatory support devices for bridge to heart transplantation, bridge to recovery, or destination therapy

Pulsatile blood pump with a linear drive actuator

The main purpose of this study was to develop an implantable direct-electromagnetic left ventricular assist system driven by a linear actuator (linear LVAS). The linear LVAS is a pulsatile pump with a pusher plate that is driven directly by a linear oscillatory actuator (LOA) without any movement converters. This prototype pump unit with a LOA was 100 mm in diameter, 50 mm in thickness, and weighed 740 g. The full-fill/full-eject driving method was applied to the control algorithm. In addition, a mechanism to detect and release sucking was realized to overcome this problem that accompanies the active-filling type of VAS. The performance of the linear LVAS was evaluated in a long-term animal experiment using a goat (56 kg). The goat survived for 42 days. The reason why we terminated this experiment was that thrombus was found in the pump. There was no frictional debris found around the LOA. The linear LVAS did not exhibit electrical or mechanical problems during the first animal experiment.

The development of core-type Transcutaneous Energy Transmission System for artificial heart

Recently, Artificial Heart (AH) is recognized as the alternate method of the heart graft. Though there are many problems and defect on AH, long term durability, miniaturization and weight saving interfaced with flow rate performance, efficiency of device. Considering rehabilitation into the society and advancement of QOL (Quality of Life), the construction of power source which supplies electric power to the device is important and has many problems. Especially, the electric feeder line restricts behavior of the transplant recipient and disturbs rehabilitation into the society. For solving these problems, Transcutaneous Energy Transmission System (TETS) is noticed and studied. This study proposes core-type TETS. It achieves high magnetic coupling compared with air-core-type TETS which is carried out on clinical study. Because core-type TETS has high magnetic coupling, it is possible to reduce the input current and to miniaturize transformer size. This paper mentions the characteristic of core-type TETS.

The re-design at the transformer portion of transcutaneous energy transmission system for all implantable devices

All implantable devices, such as an artificial heart, an artificial lung, a pacemaker, a defibrillator, need electric power. So the electric power supply through the skin is requested. Then, it is transcutaneous energy transmission system (TETS) that has been studied and used a lot. TETS is the system which performs an electric power supply by non-contact transcutaneously using the electromagnetic induction phenomenon of an external primary side coil and a secondary side coil in human body. In this research, we are developing the core type TETS which applied for the implantable devices. In this paper, corresponding to various conditions, such as a difference in required electric power and transmission distance change, the core type transformer which can hold high transmission efficiency is designed.

Mechanical circulatory support devices (MCSD) in Japan: current status and future directions

The current status and future directions of mechanical circulatory support devices (MCSDs) in Japan are reviewed. Currently used clinical MCSDs, both domestic and imported systems and continuous flow devices that are coming into the clinical arena are emphasized. Clinical MCSDs include the extracorporeal pulsatile Toyobo and Zeon systems and the implantable Novacor and HeartMate I VE. A thorough review is presented of single-ventricle continuous flow MCSDs such as the Terumo DuraHeart and the SunMedical EVAHEART and the biventricular Miwatec/Baylor systems that are on the horizon. The future directions in management of end-stage cardiac patients with MCSDs are discussed, focusing on (1) device selection - pulsatile versus continuous flow devices; (2) single-ventricle support, biventricular support, or replacement; (3) bridge to transplantation, destination therapy, or bridge to recovery; and (4) government regulatory processes and the medical industry. We hope to promote the quality of life (QOL) of end-stage cardiac patients as well as the medical industry in Japan.

Magnetically Suspended Centrifugal Blood Pump With a Radial Magnetic Driver

A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps.

One Piece Ultracompact Totally Implantable Electromechanical Total Artificial Heart for Permanent Use

An ultracompact, one piece, totally implantable electromechanical total artificial heart (TAH) has been developed as a permanent replacement for failing hearts. It consists of left and right pusher plate blood pumps (stroke volume 55 ml) made of titanium alloy (Ti-6Al-7Nb) sandwiching a miniaturized electromechanical actuator between them. The diameter of the TAH is 90 mm, with a thickness of 70 mm, yielding an overall volume of 400 ml. It weighs 450 g. Although it is miniaturized, it provided a maximum pump output of 8 L/min against a left afterload of 100 mm Hg. It required approximately 12 watts to provide a pump output of 6.5 L/min with maximum efficiency of 13.5%. To balance left and right flow, the right stroke length was made 10% shorter than the left, and an auxiliary compliance chamber was used to compensate for additional flow differences between them. Motor commutation pulses and a Hall effect pusher plate sensor signal were used in the controller to implement the left master alternate variable rate mode. The calf fitting study revealed excellent anatomic compatibility, and the first successful survivor was obtained in December 2001. Studies of system endurance and biocompatibility are required to ensure long-term reliability. This TAH is promising for permanent replacement of the failing heart as well as for bridge to heart transplantation for the smaller size group of end-stage cardiac patients.