The ongoing quest for the first total artificial heart as destination therapy

Many patients with end-stage heart disease die because of the scarcity of donor hearts. A total artificial heart (TAH), an implantable machine that replaces the heart, has so far been successfully used in over 1,700 patients as a temporary life-saving technology for bridging to heart transplantation. However, after more than six decades of research on TAHs, a TAH that is suitable for destination therapy is not yet available. High complication rates, bulky devices, poor durability, poor biocompatibility and low patient quality of life are some of the major drawbacks of current TAH devices that must be addressed before TAHs can be used as a destination therapy. Quickly emerging innovations in battery technology, wireless energy transmission, biocompatible materials and soft robotics are providing a promising opportunity for TAH development and might help to solve the drawbacks of current TAHs. In this Review, we describe the milestones in the history of TAH research and reflect on lessons learned during TAH development. We summarize the differences in the working mechanisms of these devices, discuss the next generation of TAHs and highlight emerging technologies that will promote TAH development in the coming decade. Finally, we present current challenges and future perspectives for the field.

Appropriate control time constant in relation to characteristics of the baroreflex vascular system in 1/R control of the total artificial heart

1/R control is a physiological control method of the total artificial heart (TAH) with which long-term survival was obtained with animal experiments. However, 1/R control occasionally diverged in the undulation pump TAH (UPTAH) animal experiment. To improve the control stability of the 1/R control, appropriate control time constant in relation to characteristics of the baroreflex vascular system was investigated with frequency analysis and numerical simulation. In the frequency analysis, data of five goats in which the UPTAH was implanted were analyzed with first Fourier transform technique to examine the vasomotion frequency. The numerical simulation was carried out repeatedly changing baroreflex parameters and control time constant using the elements-expanded Windkessel model. Results of the frequency analysis showed that the 1/R control tended to diverge when very low frequency band that was an indication of the vasomotion frequency was relative high. In numerical simulation, divergence of the 1/R control could be reproduced and the boundary curves between the divergence and convergence of the 1/R control varied depending on the control time constant. These results suggested that the 1/R control tended to be unstable when the TAH recipient had high reflex speed in the baroreflex vascular system. Therefore, the control time constant should be adjusted appropriately with the individual vasomotion frequency.

Livestock in biomedical research: history, current status and future prospective

Livestock models have contributed significantly to biomedical and surgical advances. Their contribution is particularly prominent in the areas of physiology and assisted reproductive technologies, including understanding developmental processes and disorders, from ancient to modern times. Over the past 25 years, biomedical research that traditionally embraced a diverse species approach shifted to a small number of model species (e.g. mice and rats). The initial reasons for focusing the main efforts on the mouse were the availability of murine embryonic stem cells (ESCs) and genome sequence data. This powerful combination allowed for precise manipulation of the mouse genome (knockouts, knockins, transcriptional switches etc.) leading to ground-breaking discoveries on gene functions and regulation, and their role in health and disease. Despite the enormous contribution to biomedical research, mouse models have some major limitations. Their substantial differences compared with humans in body and organ size, lifespan and inbreeding result in pronounced metabolic, physiological and behavioural differences. Comparative studies of strategically chosen domestic species can complement mouse research and yield more rigorous findings. Because genome sequence and gene manipulation tools are now available for farm animals (cattle, pigs, sheep and goats), a larger number of livestock genetically engineered (GE) models will be accessible for biomedical research. This paper discusses the use of cattle, goats, sheep and pigs in biomedical research, provides an overview of transgenic technology in farm animals and highlights some of the beneficial characteristics of large animal models of human disease compared with the mouse. In addition, status and origin of current regulation of GE biomedical models is also reviewed.

Fundamental analysis and development of the current and voltage control method by changing the driving frequency for the transcutaneous energy transmission system

We have been developing transcutaneous energy transmission system (TETS) for a ventricular assist device, shape memory alloy (SMA) fibered artificial organs and so on, the system has high efficiency and a compact size. In this paper, we summarize the development, design method and characteristics of the TETS. New control methods for stabilizing output voltage or current of the TETS are proposed. These methods are primary side, are outside of the body, not depending on a communication system from the inside the body. Basically, the TETS operates at the fixed frequency with a suitable compensation capacitor so that the internal impedance is minimalized and a flat load characteristic is obtained. However, when the coil shifted from the optimal position, the coupling factor changes and the output is fluctuated. TETS has a resonant property; its output can be controlled by changing the driving frequency. The continuous current to continuous voltage driving method was implemented by changing driving frequency and setting of limitation of low side frequency. This method is useful for battery charging system for electrically driven artificial hearts and also useful for SMA fibered artificial organs which need intermittent high peak power comsumption. In this system, the internal storage capacitor is charged slowly while the fibers are turned off and discharge the energy when the fibers are turned on. We examined the effect of the system. It was found that the size and maximum output of the TETS would able to be reduced.

An insight into short- and long-term mechanical circulatory support systems

Cardiogenic shock due to acute myocardial infarction, postcardiotomy syndrome following cardiac surgery, or manifestation of heart failure remains a clinical challenge with high mortality rates, despite ongoing advances in surgical techniques, widespread use of primary percutaneous interventions, and medical treatment. Clinicians have, therefore, turned to mechanical means of circulatory support. At present, a broad range of devices are available, which may be extracorporeal, implantable, or percutaneous; temporary or long term. Although counter pulsation provided by intra-aortic balloon pump (IABP) and comprehensive mechanical support for both the systemic and the pulmonary circulation through extracorporeal membrane oxygenation (ECMO) remain a major tool of acute care in patients with cardiogenic shock, both before and after surgical or percutaneous intervention, the development of devices such as the Impella or the Tandemheart allows less invasive forms of temporary support. On the other hand, concerning mid-, or long-term support, left ventricular assist devices have evolved from a last resort life-saving therapy to a well-established viable alternative for thousands of heart failure patients caused by the shortage of donor organs available for transplantation. The optimal selection of the assist device is based on the initial consideration according to hemodynamic situation, comorbidities, intended time of use and therapeutic options. The present article offers an update on currently available mechanical circulatory support systems (MCSS) for short and long-term use as well as an insight into future perspectives.

The helical flow total artificial heart: implantation in goats

To realize a total artificial heart (TAH) with high performance, high durability, good anatomical fitting, and good blood compatibility, the helical flow TAH (HFTAH) has been developed with two helical flow pumps having hydrodynamic levitation impeller. The HFTAH was implanted in goats to investigate its anatomical fitting, blood compatibility, mechanical stability, control stability, and so on. The size of the HFTAH was designed to be 80 mm in diameter and 84 mm wide. The maximum output was 19 L/min against 100 mmHg of pressure head. Eight adult female goats weighting from 45 to 56.3 kg (average 49.7 kg) were used. Under the extracorporeal circulation, natural heart was removed at the atrioventricular groove and the HFTAH was implanted. The HFTAH was driven with a pulsatile mode. The 1/R control was applied when the right atrial pressure recovered. The HFTAH could be implanted with good anatomical fitting in all goats. Two goats survived for more than a week. One goat is ongoing. Other goats did not survive for more than two days with various reasons. In the goats that survived for more than a week, the hydrodynamic bearing was worn and broken, which indicated that the bearing touched to the shaft. The cause was supposed to be the influence of the sucking effect. The potential of the HFTAH could be demonstrated with this study. The stability of the hydrodynamic bearing in a living body, especially the influence of the sucking effect, was considered to be very important and a further study should be necessary.

Emergency Life Support System aiming preprimed oxygenator

Development have been achieved of a new blood pump for next generation Percutaneous Cardio-Pulmonary Support (PCPS) system and a novel surface coating method for silicone membrane hollow fiber by physical adsorption using a copolymer composed of a 2-Methacryloyloxyethyl phosphorylcholine (MPC) unit and a hydrophobic unit. The new blood pump, named the Troidal Convolution Pump (TCP), is based on the principle of a cascade pump and perfused 5 L/min and 350 mmHg at 2450 rpm. The novel copolymer composed of 30% MPC unit and 3-(methacryloyloxy) propyltris (trimethylsiloxy) silane (MPTSSi) unit (PMMSi30) was the most suitable molecular design on a silicone surface. The PMMSi30 coated surface adsorbed 7.2 % as much protein a non-coated surface adsorbed.

Total artificial heart

End-stage heart failure represents a highly morbid condition for the patient with limited treatment options. From a surgical perspective, the treatment options for effective long-term survival are usually limited to heart transplantation, heart-lung transplantation or implantation of a destination mechanical circulatory support device. Assuming an advanced heart-failure patient is indeed deemed a candidate for transplantation, the patient is subject to shortages in donor organ availability and thus possible further decompensation and potential death while awaiting transplantation. Various extracorporeal and implantable ventricular-assist devices (VADs) may be able to provide temporary or long-term circulatory support for many end-stage heart-failure patients but mechanical circulatory support options for patients requiring long-term biventricular support remain limited. Implantation of a total artificial heart (TAH) currently represents one, if not the best, long-term surgical treatment option for patients requiring biventricular mechanical circulatory support as a bridge to transplant. The clinical applicability of available versions of positive displacement pumps is limited by their size and complications. Application of continuous-flow technology can help in solving some of these issues and is currently being applied in the research towards a new generation of smaller and more effective TAHs. In this review, we discuss the history of the TAH, its development and clinical application, implications for anaesthetic management, published outcomes and the future outlook for TAHs.

Domestic animal models for biomedical research

Experimental animals in biomedical research provide insights into disease mechanisms and models for determining the efficacy and safety of new therapies and for discovery of corresponding biomarkers. Although mouse and rat models are most widely used, observations in these species cannot always be faithfully extrapolated to human patients. Thus, a number of domestic species are additionally used in specific disease areas. This review summarizes the most important applications of domestic animal models and emphasizes the new possibilities genetic tailoring of disease models, specifically in pigs, provides.

Artificial organs 2011: a year in review

In this Editor's Review, articles published in 2011 are organized by category and briefly summarized. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, and the International Society for Rotary Blood Pumps, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level."Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ replacement, recovery, and regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal would not be possible. We also express our special thanks to our Publisher, Wiley-Blackwell, for their expert attention and support in the production and marketing of Artificial Organs. In this Editor's Review, that historically has been widely well-received by our readership, we aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ replacement, recovery, and regeneration. We look forward to recording further advances in the coming years.