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Total Artificial Heart (total + artificial_heart)

Distribution by Scientific Domains

Medical Sciences	90%

Selected Abstracts

Japanese Guidance for Ventricular Assist Devices/Total Artificial Hearts

ARTIFICIAL ORGANS, Issue 9 2010
Takashi Yamane
Abstract To facilitate research and development (R&D) and to expedite the review processes of medical devices, the Ministry of Health, Labor and Welfare (MHLW) and the Ministry of Economy, Trade and Industry (METI) founded a joint committee to establish guidance for newly emerging technology. From 2005 to 2007, two working groups held discussions on ventricular assist devices and total artificial hearts, including out-of-hospital programs, based on previous guidance documents and standards. Based on this discussion, the METI published the R&D Guidelines for innovative artificial hearts in 2007, and in 2008 the MHLW published a Notification by Director regarding the evaluation criteria for emerging technology. [source]

Open-loop Analysis of Transfer Characteristics from Blood Pressure to Heart Rate Using an Effectively Total Artificial Heart

ARTIFICIAL ORGANS, Issue 1 2004
Akira Tanaka
Abstract:, ,It is desirable for the dynamic behavior of the drive rate of the artificial heart to be as similar as possible to that of the recipient's heart rate (HR) before implantation. This requires a model which can simulate the behavior of HR on the basis of only the information measured with the limited number of approvable implanted sensors. This article provides a linear time series model for explaining the behavior of HR only with aortic pressure and right atrial pressure. This could be obtained from open-loop analysis using a total artificial heart, which was introduced for measuring HR in vivo and for eliminating its effect on blood pressure. The model was identified in a goat equipped with a special biventricular assist device called the effectively total artificial heart (ETAH). The ETAH was introduced to make an open loop and awake situation in the animal with almost intact autonomic nerves, which could enhance the accuracy and reliability of the identification of the model. The adequacy of the proposed model was ascertained in several data sets measured in two goats, which were different from the data set used for identification. Most of the mean estimation errors were less than 3 beats/min and auto-correlation analysis showed approvable statistical appropriateness. However, it was clarified through comparison with the 1/R control method that the proposed model has a few problems still to be solved before its future implementation as an automatic controller of the TAH. [source]

Improvement on the Auxiliary Total Artificial Heart (ATAH) Left Chamber Design,

ARTIFICIAL ORGANS, Issue 5 2003
Aron Andrade
Abstract: The auxiliary total artificial heart (ATAH) is an electromechanically driven artificial heart with reduced dimensions, which is able to be implanted in the right thoracic or abdominal cavities of an average human patient without removing the natural heart or the heart neurohumoral inherent control mechanism for the arterial pressure. This device uses a brushless direct current motor and a mechanical actuator (roller screw) to move two diaphragms. The ATAH's beating frequency is regulated through the change of the left preload, based on Frank-Starling's law, assisting the native heart in obtaining adequate blood flow. The ATAH left and right stroke volumes are 38 ml and 34 ml, respectively, giving approximately 5 L/min of cardiac output at 160 bpm. Flow visualization studies were performed in critical areas on the ATAH left chamber. A closed circuit loop was used with water and glycerin (37%) at 25°C. Amberlite particles (80 mesh) were illuminated by a 1 mm planar helium-neon laser light. With left mean preload fixed at 10 mm Hg and the afterload at 100 mm Hg, the heart rate varied from 60 to 200 bpm. Two porcine valves were used on the inlet and outlet ports. The flow pattern images were obtained using a color micro-camera and a video recorder. Subsequently, these images were digitized using a PC computer. A persistent stagnant flow was detected in the left chamber inlet port. After improvement on the left chamber design, this stagnant flow disappeared. [source]

Totally Implantable Total Artificial Heart for Clinical Application

ARTIFICIAL ORGANS, Issue 3 2002
Ph.D. Emeritus Editor-in-ChiefArticle first published online: 4 APR 200, Yukihiko Nosé M.D.
No abstract is available for this article. [source]

Development of an electrohydraulic total artificial heart system: Improvement of pump unit

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 9 2010
Akihiko Homma
Abstract An electrohydraulic total artificial heart (EHTAH) system has been developed. The EHTAH system consists of diaphragm-type blood pumps, and electrohydraulic actuator, an internal control unit, a transcutaneous energy transfer system (TETS), a transcutaneous optical telemetry system (TOTS), and an internal battery. The reciprocating rotation of the impeller generates oil pressure that drives the blood pumps at alternating intervals. The blood pumps and the actuator were successfully integrated into the pump unit without oil conduits. As a result of miniaturizing the blood pumps and the actuator, the displacement volume and weight of the EHTAH system were decreased to 872 ml and 2492 g, respectively. Furthermore, the maximum flow rate and efficiency increased up to 12 L/min and 15.4%. The pump units and the EHTAH systems were successfully implanted in 36 calves weighing from 55 to 87 kg. In the longest case, a calf with the pump unit survived for 87 days and a calf with the EHTAH system survived for 70 days. The EHTAH system was powered by the TETS, and was powered every day by the internal battery for 40 minutes. These results indicate that the EHTAH system has the potential to become a fully implantable cardiac replacement system. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(9): 34,46, 2010; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10220 [source]

Experience with over 1000 Implanted Ventricular Assist Devices

JOURNAL OF CARDIAC SURGERY, Issue 3 2008
Evgenij V. Potapov M.D.
We present our experience since 1987. Subjects and Methods: Between July 1987 and December 2006, 1026 VADs were implanted in 970 patients. Most of them were men (81.9%). The indications were: cardiomyopathy (n = 708), postcardiotomy heart failure (n = 173), acute myocardial infarction (n = 36), acute graft failure (n = 45), a VAD problem (n = 6), and others (n = 2). Mean age was 46.1 (range 3 days to 78) years. In 50.5% of the patients the VAD implanted was left ventricular, in 47.9% biventricular, and in 1.5% right ventricular. There were 14 different types of VAD. A total artificial heart was implanted in 14 patients. Results: Survival analysis showed higher early mortality (p < 0.05) in the postcardiotomy group (50.9%) than in patients with preoperative profound cardiogenic shock (31.1%) and patients with preoperative end-stage heart failure without severe shock (28.9%). A total of 270 patients were successfully bridged to heart transplantation (HTx). There were no significant differences in long-term survival after HTx among patients with and without previous VAD. In 76 patients the device could be explanted after myocardial recovery. In 72 patients the aim of implantation was permanent support. During the study period 114 patients were discharged home. Currently, 54 patients are on a device. Conclusions: VAD implantation may lead to recovery from secondary organ failure. Patients should be considered for VAD implantation before profound, possibly irreversible, cardiogenic shock occurs. In patients with postcardiotomy heart failure, a more efficient algorithm should be developed to improve survival. With increased experience, more VAD patients can participate in out-patient programs. [source]

Costs and Insurance Coverage Associated with Permanent Mechanical Cardiac Assist/Replacement Devices in the United States

JOURNAL OF CARDIAC SURGERY, Issue 4 2001
Roger W. Evans Ph.D.
Each year over 50,000 persons in the United States could potentially benefit from some form of permanent cardiac replacement or assistance. Approximately 7000 of these persons get on the waiting list for a transplant, and 2300 are transplanted. About 2000 patints are reportedly exposed to a mechanical cardiac assist device, most often as a bridge to transplant. The majority of persons who might benefit from cardiac replacement are never referred for treatment and, thus, the number of deaths on the waiting list is a misleading indicator of access to transplantation and overall patient mortality. The total economic burden associated with coronary artery disease and congestive heart failure now exceeds $140 billion each year, with approximately $700 million directly spent on heart transplant procedures alone. If a viable total artificial heart is devised to replace a failed heart, or a ventriular assist system to permanently assist a failing heart, direct aggregate expenditures alone are likely to be somewhere between $5.4 and $24.0 billion annually. Based on individual patient care costs, as well as aggregate national expenditures, insurers will be reluctant to pay for the permanent use of such devices, even though cost is reportedly not a consideration in coverage decisions. Today, medical benefits and added value are concepts that will shape the coverage determination process, as will increasingly liberal policies regarding payment for treatment costs in relationship to clinical trials. Nonetheless, resource allocation and rationing decisions loom large as strange "characters at play" on an international economic "stage," while being "directed" by worldwide health care needs. [source]

Development of Mechanical Circulatory Support Devices in China

ARTIFICIAL ORGANS, Issue 11 2009
Wei Wang
Abstract Myocardial dysfunction leading to low cardiac output syndrome is a common clinical pathophysiological state. Currently, the use of mechanical circulatory support (MCS) is an essential aspect of the treatment of patients with cardiac failure. Several groups in China are engaged in the design and development of MCS devices. These devices can be classified as pulsatile, rotary, and total artificial heart (TAH). There are two types of pulsatile pump, which are driven by air (pneumatic). One of these pumps, the Luo-Ye pump, has been used clinically for short-term support since 1998. The other is a push-plate left ventricular device, which has a variable rate mode. Various rotary devices are classified into axial and centrifugal pumps, depending on the impeller geometry. Most rotary pumps are based on the maglev principle, and some types have been used clinically. Others are still being studied in the laboratory or in animal experiments. Furthermore, certain types of total implantable pump, such as the UJS-III axial pump and the UJS-IV aortic valvo-pump, have been developed. Only one type of TAH has been developed in China. The main constituents of this artificial heart are two axial pumps, two reservoir tanks mimicking the right and left atria, flow meters, two pressure gauges, and a resistance adaptor. Although the development of mechanical assist devices in China is still in a nascent stage, a number of different types of MCS devices are currently being studied. [source]

Open-loop Analysis of Transfer Characteristics from Blood Pressure to Heart Rate Using an Effectively Total Artificial Heart

Recent Progress in Artificial Organ Research at Tohoku University

ARTIFICIAL ORGANS, Issue 1 2003
Tomoyuki Yambe
Abstract: Tohoku University has developed various artificial organs over the last 30 years. Pneumatic driven ventricular assist devices with a silicone ball valve have been designed by the flow visualization method, and clinical trials have been performed in Tohoku University Hospital. On the basis of these developments, a pneumatic driven total artificial heart has been developed and an animal experimental evaluation was conducted. The development of artificial organs in Tohoku University has now progressed to the totally implantable type using the transcutaneous energy transmission system with amorphous fibers for magnetic shielding. Examples of implantable systems include a vibrating flow pump for ventricular assist device, an artificial myocardium by the use of shape memory alloy with Peltier elements, and an artificial sphincter for patients with a stoma. An automatic control system for artificial organs had been developed for the ventricular assist devices including a rotary blood pump to avoid suction and to maintain left and right heart balance. Based upon the technology of automatic control algorithm, a new diagnostic tool for evaluating autonomic nerve function has been developed as a branch of artificial organ research and this new machine has been tested in Tohoku University Hospital. Tohoku University is following a variety of approaches aimed at innovation in artificial organs and medical engineering fields. [source]