Compact Ventricular Assist Device and Total Artificial Heart Using Undulation Pump

The development of mechanical circulatory support devices at the University of Tokyo has focused on developing a small total artificial heart (TAH) since achieving 532 days of survival of an animal with a paracorporial pneumatically driven TAH. The undulation pump was invented to meet this purpose. The undulation pump total artificial heart (UPTAH) is an implantable TAH that uses an undulation pump. To date, the UPTAH has been implanted in 71 goats weighting from 39 to 72 kg. The control methods are very important in animal experiments, and sucking control was developed to prevent atrial sucking. Rapid left-right balance control was performed by monitoring left atrial pressure to prevent acute lung edema caused by the rapid increase in both arterial pressure and venous return associated with the animal becoming agitated. Additionally, 1/R control was applied to stabilize the right atrial pressure. By applying these control methods, seven goats survived more than 1 month. The maximum survival period was 63 days. We are expecting to carry out longer term animal experiments with a recent model of TAH. In addition to the TAH, an undulation pump ventricular assist device (UPVAD), which is an implantable ventricular assist device (VAD), has been in development since 2002, based on the technology of the UPTAH. The UPVAD was implanted in six goats; three goats survived for more than 1 month. While further research and development is required to complete the the UPVAD system, the UPVAD has good potential to be realized as an implantable pulsatile-flow VAD.

Heart Transplant Outcomes After Total Artificial Heart

The total artificial heart (TAH) is a form of mechanical circulatory support that involves resection of the native ventricles followed by placement of a device that can restore total pulmonary and systemic flow. Given the increasing burden of congestive heart failure and cardiovascular disease, the number of people in need of cardiac replacement therapy will continue to grow. Despite aggressive efforts to expand the donor pool, the number of heart transplants in the United States (US) has plateaued at less than 3000 per year. In addition, there is increasing recognition of the long-term complications of current generation left ventricular assist devices such as progressive aortic insufficiency, complications related to blood trauma, and both early and delayed right ventricular failure. These factors may serve to expand the role of the TAH in the treatment of patients with end-stage heart failure particularly if new generation devices are developed that are durable, have an improved safety profile, and are totally implantable. PURPOSE OF REVIEW: To review the role and current evidence of the use of the TAH in the management of advanced heart failure and discuss development of recent TAHs that may have an impact on the field in the near future. RECENT FINDINGS: Many patients that receive a heart transplant are bridged with a mechanical support device, most commonly a left ventricular assist device (LVAD). However, there is a small subset of patients with profound biventricular (BV) failure or structural abnormalities that preclude LVAD placement, who will require support with a biventricular assist device (BiVAD) or TAH. There are numerous studies showing the efficacy of the TAH in bridging to transplantation. Also, recent studies have shown equal rates of bridging to transplantation between patients receiving a TAH compared to a BiVAD. However, BiVAD support has a higher incidence of stroke in addition to complications related to the native heart such as arrhythmias and valve dysfunction. Currently, there are multiple new generation artificial hearts in both preclinical development and in clinical trials for both bridge to transplant and destination therapy. TAH have been shown to be effective for circulatory support in select patients with end-stage heart failure. Current LVADs are associated with significant long-term complications related to retention of the native heart and pump design. Many of these complications may be addressed by the increased use of cardiac replacement therapy, i.e., total artificial hearts. Multiple generations of both pulsatile and advanced design continuous flow TAH are under development which have the potential to expand the role of TAHs.

Successful Use of the Total Artificial Heart in the Failing Fontan Circulation

The University of Tokyo has been involved in research and development of the artificial heart since 1959. This paper is a brief review of 40 years of total artificial heart research in the University of Tokyo. Many types of artificial heart and various kinds of materials, blood pumps, valves, drive units, control methods, and pathophysiology have been investigated in our original fashion. The longest survival was 532 days for a goat with a total artificial heart (TAH) placed on the chest wall. These results made us take a step toward the development of an implantable TAH. Two kinds of implantable TAH are now being developed: FTPTAH (flow-transformed pulsatile total artificial heart) and UPTAH (undulation pump total artificial heart). Recently, a goat survived for 31 days with an UPTAH.

Research into the subject of total artificial heart (TAH) began in the USA in 1963 under the impetus of the American Congress; however, it soon hit the snags of haemocompatibility, autoadjustment of operation to the patient’s physiological needs, miniaturization, portable energy and reliability in the long run. Michael DeBakey was the first to use an external heart pump successfully in a patient as a left ventricular bypass pump in 1966. The first TAH, called Liotta-Heart, was implanted by Denton Cooley in 1969 in Houston, TX, USA. The 47-year old male recipient was bridged for 65 h until heart transplantation was possible. This first TAH was developed by the Argentinian surgeon Domingo Liotta who was hired at Baylor College of Medicine in Houston, Texas as Director of the Artificial Heart Program by Michael DeBakey in 1961 and returned to his homeland later. Finally it remained unclear how many Liotta-TAHs were implanted. The next TAH, called Jarvik-7, was implanted in 1982 to a retired dentist. The patient survived 112 days. The Jarvik-7 heart led to a remarkable reaction in the media. Meanwhile the original Jarvik-7 heart was further developed, named CardioWest and finally placed on the market under the name Syncardia TAH. The Syncardia TAH has two pneumatically driven ventricles, separated from each other and with two mechanical valves each. It was originally implanted mainly in Europe (France and then Germany). In 2004, the device was approved by the FDA as a bridge to transplant, allowing several US centres to implant the device. Owing to the introduction of portable drivers in 2010, patients could now be discharged home and the utilization of the Syncardia TAH increased. Over 30 years, more than 1300 were implanted. The company received a humanitarian device exemption to test its TAH for destination therapy in 2012, but has not yet begun clinical trials for this indication. The patient who lived the longest time on the Syncardia TAH was successfully bridged to heart transplantation after 4 years of support. The Syncardia TAH has ventricles of 70 ml, which does not fit in smaller women and adolescent patients. Meanwhile, Syncardia started to develop a smaller version with 50 ml ventricles. The AbioCor® TAH was developed by the company AbioMed. It was the world’s first fully implantable and completely self-contained artificial heart. The internal battery is charged by a transcutaneous energy transfer (TET) system. A 71-year old man survived for 17 months with the AbioCor TAH. A feasibility study in fourteen patients and the end-point of 60-day survival led to an initial rejection by the FDA circulatory system devices advisory panel. In 2006, the FDA approved the AbioCor TAH as a humanitarian use device because of its limited market for patients ineligible for transplantation. The device has since been implanted according to our knowledge in one case (2009).

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.

Total artificial heart(TAH) is the present for patients with biventricular failure, and all other treatments have no significant effect and are unable to obtain donor organs in time or the final choice for receiving organ transplantation.After 50 years of research, TAH, which has already been put into clinical application, has the CardioWest TAH of SynCardia Systems, Abiocor TAH of Abiomedcompany and Carmat TAH of Carmat company.The application of TAH can lead to serious complications.The most common complications include infection, severe postoperative bleeding, and thromboembolism, and other possible complications including liver, kidney, lung, and nervous system dysfunction.Because of various objective reasons, mechanical circulation auxiliary devices, including ventricular assist and all artificial heart, have been limited in our country's research and development and application, and it has become a conventional treatment choice abroad.In addition, in clinical applications, TAH is used for adults over 18 years of age.There is still a long way to go for the application of TAH implantation in children. Key words: Total atificial heart; Heart failure; Complication

Maximal Exercise Response Is Reduced in Patients with the Total Artificial Heart

Patients with isolated left ventricular failure may have positive outcomes after being implanted with a left ventricular assist device. Unfortunately, almost half of patients with heart failure and reduced ejection fraction also have evidence of right ventricular dysfunction. For a subset of this population with severe biventricular failure, or those who develop right ventricular dysfunction after left ventricular assist device implantation, patients may necessitate biventricular assist devices or the total artificial heart. This overview of mechanical circulatory support devices will enhance nurses' ability to differentiate criteria for implantation, current practice, and outcomes with a focus on durable ventricular assist devices and the total artificial heart. A review of the literature involved searching CINAHL and PubMed databases using keywords biventricular assist devices, total artificial heart, and durable mechanical circulatory support. Results were narrowed to articles based on adults, 18 years or older. Seventy-eight relevant articles were identified, and 8 articles compared the durable biventricular assist devices. Similar patient outcomes were found when comparing the use of left ventricular assist devices as biventricular support versus the total artificial heart. The decision to implant the appropriate durable mechanical circulatory support for a patient in biventricular failure is complex and dependent on patient factors.

It was 1957 when one of the authors (W.J.K.) began research on total mechanical artificial heart implantation. From that time on it was difficult, until only very recently, to keep an experimental animal alive with an artificial heart for longer than two or three days. However, in 1971 the longstanding question of whether the artificial heart could sustain the animal’s entire circulation beyond the time of recovery from surgery and maintain the animal in a reasonable physiological state with a mechanical pump was answered. To date at least three groups in the country have been able to sustain a calf with an implanted mechanical heart for over three days. These long-term survivors with total mechanical hearts have brought forth a few unanswered questions.

An experimental wearable air supply for pneumatic artificial hearts and ventricular assist devices has been built and tested. The unit eliminates the need for tethering to a large, stationery driver. The miniaturized air supply is designed for ambulatory patients with implanted pulsatile pneumatic total artificial hearts (TAH) or pneumatic left-ventricular assist devices (LVAD), to permit mobility in clinical and home settings. The device has major short-term utility as a supply for pneumatic TAH or VAD bridges in patients awaiting heart transplants. The system design for the wearable driver includes a novel, fast rotary compressor, driven by a brushless direct current (DC) motor to supply air to the ventricle through an electromagnetically actuated directional valve, all controlled by a microcomputer. Stroke volume from 0 to 200 cc; pulse rate from 60 to 160 bpm, and duty cycle from 33% to 50% are selected on a keyboard, and the selected or measured parameters can be shown on a liquid crystal display. For control of delivery from a single ventricular assist device, stroke volume is controlled by variation of compressor speed. In the wearable air supply for a TAH, a single compressor drives both ventricles alternately through a double-acting directional valve. Air volume delivered to the left ventricle is adjusted by variation of compressor speed, and air volume to the right ventricle by variation of ejection time. The effect on blood flow rate of the lower impedance to the right ventricle is compensated by provision of a two-stage compressor, in which a single stage drives the right ventricle, and both stages connected in parallel drive the left ventricle. The overall dimensions of the prototype air supply for driving either a TAH or LVAD are 4.5 by 7.8 by 4.5 inches, including an emergency battery with a duration of 15 to 30 min depending on load. The weight is presently 5.5 lb, but this will be reduced in a production design and for a dedicated LVAD air supply. The size and weight of a separately worn, rechargeable battery pack depend on the load and desired duration of operation.

Therapeutic options in end stage heart failure include cardiac transplantation or mechanical circulatory support: Left Ventricular Assist Device (LVAD) or Total Artificial Heart (TAH). These devices have relatively high power requirements (5–80 W). Existing power supplies to LVAD and TAH are via percutaneous drivelines with a high frequency of complications including infection. We have developed a wireless Transcutaneous Energy Transmission (TET) waveform protocol and system technology which address the major clinical drawbacks of existing systems: skin tissue thermal effect and system durability. Conventional single-channel TET solutions have significant limitations, including inefficient energy transfer characteristics and high energy density levels producing tissue thermal effects. A reduced lifetime of the internal rechargeable battery is an additional drawback. In the proposed novel system, a multi-channel, time-space multiplexed and pulsed RF transmission waveform transcutaneous power delivery approach, is presented for sustained internal energy supply to high-power rated implantable devices. The bench system prototype performance evaluation results, revealed excellent high-energy transfer efficiency and safer management of lower energy density levels. In conclusion, the proposed pulsed transmission waveform protocol and multi-channel concepts can be configured for individual high-power rated LVAD devices to effectively mitigate tissue thermal effects and to prolong backup battery lifetime.

Reduced Pulsatility Induces Periarteritis in Kidney: Role of the Local Renin–Angiotensin System

In an attempt to explore methods to reduce total artificial heart (TAH) acceleration and sound production, in vitro measurements of TAH acceleration and sound were made when using a variety of prosthetic valves in a test ventricle. A miniature, uniaxial, high fidelity accelerometer was glued to the housing of a UTAH-100 left ventricle adjacent to the inflow and outflow ports and parallel to the axis of diaphragm excursion. A miniature, high fidelity contact microphone was glued to the opposite side of the ventricular housing between the inflow and outflow ports. Data was collected over a range of heart rates, ventricular filling volumes and control modes while using tilting disc valves (TDV) and polymer trileaflet valves (PTV). For both valve types, the peak systolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially filled and the peak diastolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially ejected. The magnitude of the acceleration with PTVs was approximately equal to 20x less than the TDVs (0.5 to 2.2 g vs. 10 to 49g). The magnitude of the sound production was also considerably less with the PTVs (28 to 49 db vs. 50 to 64 db). Diastolic acceleration and sound production was approximately twice the systolic value for the TDVs; the reserse was true for PTV sound production. These data demonstrate the substantial reduction in TAH impulse acceleration and sound production by selecting PTVs over TDSs. With PTVs, the TAH impulse acceleration is the same as the natural heart. Consequently, this ability to lower TAH acceleration and sound production to the level of the natural heart may lead to a reduction in component wear, patient discomfort and other undesirable consequences of TAH implantation.