Ueno, Atsuko; Tomizawa, Yasuko
Recently, cardiac rehabilitation has gained popularity in Japan because beneficial effects on patients' prognosis have been reported. Another reason is that cardiac rehabilitation has been covered by health insurance since 1988 in Japan. Currently, cardiac rehabilitation is covered for the diseases of angina pectoris, acute myocardial infarction, chronic heart failure (CHF), peripheral arterial disease, and diseases of the aorta and after open-heart surgery. Left ventricular assist devices (LVADs) are sometimes used in patients with progressive CHF symptoms to provide circulatory support, because in most of these patients heart failure does not improve with application of medical therapy, intra-aortic balloon pumping, or a percutaneous cardiopulmonary system. Modern VAD control systems are compact, allowing patients to carry them around without difficulty. Since patient management at the outpatient clinic has become possible, patients are able to expand the scope of their activities. Early active rehabilitation in patients implanted with a LVAD improves their condition, favorably impacts the clinical course while they await heart transplantation, and also improves posttransplant recovery. Exercise therapy is one of the important components in comprehensive cardiac rehabilitation. Exercise therapy is important to improve the quality of life of patients with LVADs. Appropriate exercise therapy is effective for patients with various cardiac conditions who undergo diverse treatments and is practiced actively by many patients. In order to facilitate cardiac rehabilitation safely and effectively for patients with serious conditions, education for health care professionals is essential. In this review, we describe the concept of rehabilitation followed by cardiac rehabilitation for patients with heart failure, patients after open-heart surgery, and patients with implanted LVADs.
Yamane, Takashi; Kyo, Shunei; Matsuda, Hikaru; Abe, Yusuke; Imachi, Kou; Masuzawa, Toru; Nakatani, Takeshi; Sase, Kazuhiro; Tabayashi, Koichi; Takatani, Setsuo; Tatsumi, Eisuke; Umezu, Mitsuo; Tsuchiya, Toshie
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. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Kirklin, James K
Mechanical circulatory support (MCS) has rapidly evolved toward continuous flow technology in adults. In the pediatric population, the Berlin EXCOR, a paracorporeal pulsatile pump, is the only MCS device specifically approved for pediatric use. The current era of pediatric MCS includes an increasing application of adult continuous flow pumps to pediatric patients. The Berlin EXCOR pulsatile pump has been studied in over 200 patients. The major limitations of this device are neurologic dysfunction (which occurs in about 30% of supported patients) and the requirement for in-hospital care until transplant. Two continuous flow pumps (HVAD and HeartMate II) have been successfully applied in children and adolescents, and the SynCardia total artificial heart has been used in adolescents. The National Heart, Lung, and Blood Institute - sponsored Pediatric Mechanically Assisted Circulatory Support registry has collected pediatric MCS data since 2012 and will provide valuable outcomes data to help refine this field. Survival with these durable devices has been generally good (except for small infants and patients with complex congenital heart disease), with nearly 50% receiving a heart transplant within 6 months. Patients with single ventricle physiology continue to pose major challenges. Two clinical trials for miniaturized adult continuous flow devices and one trial for a new pediatric pump will begin within the next year. New continuous flow devices are entering or poised to enter clinical trials. If approved, these devices will enhance the safety and variety of options for longer-term pediatric support.
Ji, Jinghua; Zhao, Wenxiang; Liu, Guohai; Shen, Yue; Wang, Fangqun
In this paper, a new high reliability linear drive device, termed as stator-permanent-magnet tubular oscillating actuator (SPM-TOA), is proposed for artificial hearts (AHs). The key is to incorporate the concept of two independent phases into this linear AH device, hence achieving high reliability operation. The fault-tolerant teeth are employed to provide the desired decoupling phases in magnetic circuit. Also, as the magnets and the coils are located in the stator, the proposed SPM-TOA takes the definite advantages of robust mover and direct-drive capability. By using the time-stepping finite element method, the electromagnetic characteristics of the proposed SPM-TOA are analyzed, including magnetic field distributions, flux linkages, back- electromotive forces (back-EMFs) self- and mutual inductances, as well as cogging and thrust forces. The results confirm that the proposed SPM-TOA meets the dimension, weight, and force requirements of the AH drive device.
Kiris, C; Kwak, D; Rogers, S; Chang, I D
Computational fluid dynamics (CFD) has become an indispensable part of aerospace research and design. The solution procedure for incompressible Navier-Stokes equations can be used for biofluid mechanics research. The computational approach provides detailed knowledge of the flowfield complementary to that obtained by experimental measurements. This paper illustrates the extension of CFD techniques to artificial heart flow simulation. Unsteady incompressible Navier-Stokes equations written in three-dimensional generalized curvilinear coordinates are solved iteratively at each physical time step until the incompressibility condition is satisfied. The solution method is based on the pseudocompressibility approach. It uses an implicit upwind-differencing scheme together with the Gauss-Seidel line-relaxation method. The efficiency and robustness of the time-accurate formulation of the numerical algorithm are tested by computing the flow through model geometries. A channel flow with a moving indentation is computed and validated by experimental measurements and other numerical solutions. In order to handle the geometric complexity and the moving boundary problems, a zonal method and an overlapped grid embedding scheme are employed, respectively. Steady-state solutions for the flow through a tilting-disk heart valve are compared with experimental measurements. Good agreement is obtained. Aided by experimental data, the flow through an entire Penn State artificial heart model is computed.
Heart transplants have been decreasing globally due to the lack of available donor hearts. As a result, the increased use of artificial hearts is anticipated as an alternative therapy. Although biocompatibility issues, such as thrombus formation/thromboembolism and infection, are still the main cause of mortality associated with artificial hearts, more than 20 different types are now clinically available after a half-century of development and experimental trials. These devices range from extracorporeal pneumatic to implantable battery-powered artificial hearts. The early development of artificial hearts logically focused on volumetric pump designs incorporating functions similar to the natural heart. Today, development has shifted toward designs that are significantly different from the natural heart. These pumps utilize axial or centrifugal flow allowing for a much simpler design, which is smaller in size and has very few moving parts. With rapid advances in technology, this new generation of artificial heart pumps is beginning to emerge as an alternative to heart transplants.
Shah, Keyur B; Tang, Daniel G; Cooke, Richard H; Harton, Suzanne; Flattery, Maureen; Katlaps, Gundars J; Kasirajan, Vigneshwar; Hess, Michael L
Engineering advancements have expanded the role for mechanical circulatory support devices in the patient with heart failure. More patients with mechanical circulatory support are being discharged from the implanting institution and will be seen by clinicians outside the immediate surgical or heart-failure team. This review provides a practical understanding of device design and physiology, general troubleshooting, and limitations and complications for implantable left ventricular assist devices (pulsatile-flow and continuous-flow pumps) and the total artificial heart. © 2011 Wiley Periodicals, Inc.
Antretter, H; Dumfarth, J; Höfer, D
To date the CardioWest™ total artificial heart is the only clinically available implantable biventricular mechanical replacement for irreversible cardiac failure. This article presents the indications, contraindications, implantation procedere and postoperative treatment. In addition to a overview of the applications of the total artificial heart this article gives a brief presentation of the two patients treated in our department with the CardioWest™. The clinical course, postoperative rehabilitation, device-related complications and control mechanisms are presented. The total artificial heart is a reliable implant for treating critically ill patients with irreversible cardiogenic shock. A bridge to transplantation is feasible with excellent results.
Pifarre, R; Sullivan, H; Montoya, A; Bakhos, M; Grieco, J; Foy, B K; Blakeman, B; Altergott, R; Lonchyna, V; Calandra, D
The proliferation of transplant programs has not been paralleled by a similar increase in the availability of organ donors. This has significantly prolonged the waiting period and consequently has resulted in increased mortality of the patients with end-stage heart disease who are awaiting transplantation. Between 1984 and 1987, 104 orthotopic heart transplants were performed at Loyola University Medical Center. During the same period, 25 patients died while waiting for a suitable donor. To reduce the mortality of our patients waiting for transplantation, we began using the total artificial heart and a ventricular assist device as a bridge to transplantation in 1988. Of 29 patients who underwent transplant procedures in 1988, 18 required either a total artificial heart (15) or a ventricular assist device (3) as a bridge to transplantation. The underlying heart conditions were ischemic cardiomyopathy (11), dilated cardiomyopathy (5), giant cell myocarditis (1), and allograft failure (1). The average duration of mechanical support was 10 days (range, 1 to 35 days). Seventeen of the supported patients had successful transplants. One patient had brain death and did not receive a heart transplant. Of the 17 patients who survived surgery, two died within 30 days: one at 17 days because of acute rejection, the other at 14 days because of a cerebral vascular event. Fifteen patients (83%) were long-term survivors. Nine of the supported patients required reoperation because of bleeding after device implantation. There was no mediastinal or incisional infection. While the mechanical device was in place, the activated clotting time was maintained between 170 and 200 seconds with the administration of heparin (400 to 1000 units per hour).(ABSTRACT TRUNCATED AT 250 WORDS)
Cook, Jason A; Shah, Keyur B; Quader, Mohammed A; Cooke, Richard H; Kasirajan, Vigneshwar; Rao, Kris K; Smallfield, Melissa C; Tchoukina, Inna; Tang, Daniel G
The total artificial heart (TAH) is a form of mechanical circulatory support in which the patient's native ventricles and valves are explanted and replaced by a pneumatically powered artificial heart. Currently, the TAH is approved for use in end-stage biventricular heart failure as a bridge to heart transplantation. However, with an increasing global burden of cardiovascular disease and congestive heart failure, the number of patients with end-stage heart failure awaiting heart transplantation now far exceeds the number of available hearts. As a result, the use of mechanical circulatory support, including the TAH and left ventricular assist device (LVAD), is growing exponentially. The LVAD is already widely used as destination therapy, and destination therapy for the TAH is under investigation. While most patients requiring mechanical circulatory support are effectively treated with LVADs, there is a subset of patients with concurrent right ventricular failure or major structural barriers to LVAD placement in whom TAH may be more appropriate. The history, indications, surgical implantation, post device management, outcomes, complications, and future direction of the TAH are discussed in this review.
Cook, Jason A.; Shah, Keyur B.; Quader, Mohammed A.; Cooke, Richard H.; Kasirajan, Vigneshwar; Rao, Kris K.; Smallfield, Melissa C.; Tchoukina, Inna
The total artificial heart (TAH) is a form of mechanical circulatory support in which the patient’s native ventricles and valves are explanted and replaced by a pneumatically powered artificial heart. Currently, the TAH is approved for use in end-stage biventricular heart failure as a bridge to heart transplantation. However, with an increasing global burden of cardiovascular disease and congestive heart failure, the number of patients with end-stage heart failure awaiting heart transplantation now far exceeds the number of available hearts. As a result, the use of mechanical circulatory support, including the TAH and left ventricular assist device (LVAD), is growing exponentially. The LVAD is already widely used as destination therapy, and destination therapy for the TAH is under investigation. While most patients requiring mechanical circulatory support are effectively treated with LVADs, there is a subset of patients with concurrent right ventricular failure or major structural barriers to LVAD placement in whom TAH may be more appropriate. The history, indications, surgical implantation, post device management, outcomes, complications, and future direction of the TAH are discussed in this review. PMID:26793338
Heilmann, Claudia; Geisen, Ulrich; Beyersdorf, Friedhelm; Nakamura, Lea; Benk, Christoph; Berchtold-Herz, Michael; Trummer, Georg; Schlensak, Christian; Zieger, Barbara
Unexplained bleeding episodes are associated with ventricular assist devices (VAD) and can occur in part due to acquired von Willebrand syndrome (AVWS). AVWS is characterised by loss of high molecular weight (HMW) multimers of von Willebrand factor (VWF) and decreased ratios of collagen binding capacity and ristocetin cofactor activity to VWF antigen. Loss of multimers can occur as VWF is subjected to increased shear stress, which occurs in presence of VADs. We studied 12 patients who required mechanical support of their native heart for terminal cardiac insufficiency. Nine patients underwent placement of a VAD, while three underwent placement of a total artificial heart (TAH), which is connected directly to heart and large cardiac vessels without cannulas. Within one day of VAD implantation, four of five patients evaluated demonstrated loss of HMW multimers and impaired VWF function. AVWS was present within two weeks of implantation in eight of nine patients, and in all seven tested patients after >/=3 months. Patients with different VAD types developed varying severities of AVWS. After VAD explantation, HMW multimers were detectable and VWF function normalised in all patients. AVWS was not observed in the TAH patients studied. Our findings demonstrate that patients with an implanted VAD experience a rapid onset of AVWS that is quickly and completely reversed after device explantation. In addition, TAH patients do not develop AVWS. These results suggest that shear stress associated with exposure of blood to VAD cannulas and tubes may contribute to the development of AVWS.
The advances in the treatment of many different heart diseases have on the one side led to a significant prolongation of life expectancy but have also contributed to an increase of patients with heart failure. This tendency is supported even more so by the demographic development of our population. The replacement of insufficient organs has always been in the focus of medical research. In the 1960's Shumway and Lower developed the technique of cardiac transplantation and also worked intensively on the treatment and diagnosis of rejection. However, it was Barnard who, in 1967 performed the first human cardiac transplantation. Other centers followed worldwide but the mortality was high and the new therapy was controversially discussed in many journals. By the introduction of cyclosporin as a new immunosuppressive agent in 1978, results improved rapidly and cardiac transplantation became an accepted therapeutic option for patients with end stage heart failure and also for children and newborns with congenital heart defects. Today, with newer immunosuppressive regimens and improved techniques, cardiac transplantation offers excellent results with a long-term survival of nearly 50% of patients after 15 years and among the pediatric population even after 20 years. However, the donor organ shortage as well as the increasing number of elderly patients with end stage heart failure has necessitated work on other alternatives. Neither stem cell transplantation nor xenotransplantation of animal organs are yet an option and there are still some obstacles to be overcome. In contrast, the development of so-called artificial hearts has made significant progress. While the first implants of totally artificial hearts were associated with many comorbidities and patients were seriously debilitated, new devices today offer a reasonable quality of life and long-term survival. Most of these systems are no longer replacing but mainly assisting the heart, which remains in place. These
Shumakov, V I; Tolpekin, V E; Melemuka, I V; Kiselev, Iu M; Vlasov, V V; Gasanov, E K; Ganin, V P; Eremin, V N; Kilasev, N B; Degtiarev, V G
The authors offer a system for auxiliary circulation (a "hybrid man-made heart"), review design varieties, describe the functioning of the system. The paper is of interest for designers of the systems for extracorporeal circulation and for practicing physicians concerned with the problems of cardiology.
Sipin, A J; Fabrey, W J; Smith, S H; Doussourd, J D; Olsen, D B
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 use of a mechanical device to support a failing heart is one of the greatest challenges in cardiothoracic practice. Many different approaches are being considered, but they share the use of many advanced engineering principles. Power supplies and the interface between artificial surfaces and the blood remain areas of difficulty. The accent is moving from console driven devices with drive lines which must cross the body wall to reach the pump, towards smaller control packs, with inductive coupling to fully contained pumps. More attention is focused on the use of axial pumps lying within the lumena of the great vessels and the ventricles. Despite the wideheld belief that mechanical pumps must confer survival advantage to the recipients, there has been no prospective study demonstrating any advantage over medical management of the failing heart. Economic considerations must be taken into account if the technology is to be available to everyone with heart failure.
Potnuru, Akshay; Wu, Lianjun; Tadesse, Yonas
A soft robotic device inspired by the pumping action of a biological heart is presented in this study. Developing artificial heart to a humanoid robot enables us to make a better biomedical device for ultimate use in humans. As technology continues to become more advanced, the methods in which we implement high performance and biomimetic artificial organs is getting nearer each day. In this paper, we present the design and development of a soft artificial heart that can be used in a humanoid robot and simulate the functions of a human heart using shape memory alloy technology. The robotic heart is designed to pump a blood-like fluid to parts of the robot such as the face to simulate someone blushing or when someone is angry by the use of elastomeric substrates and certain features for the transport of fluids.
Pathak, Vikas; Donovan, Colin; Malhotra, Rajiv
The total artificial heart is the mechanical device which is used as a bridge to the heart transplant in patients with biventricular failure. Due to the mechanical nature of the device, patients receiving total artificial heart (TAH) require to be on anticoagulation therapy. Hemorrhage and coagulopathy are few of the known complications of TAH. PMID:28250605
Pathak, Vikas; Donovan, Colin; Malhotra, Rajiv
The total artificial heart is the mechanical device which is used as a bridge to the heart transplant in patients with biventricular failure. Due to the mechanical nature of the device, patients receiving total artificial heart (TAH) require to be on anticoagulation therapy. Hemorrhage and coagulopathy are few of the known complications of TAH.
Ramirez, Angeleah; Riley, Jeffrey B; Joyce, Lyle D
To prevent thrombotic or bleeding events in patients receiving a total artificial heart (TAH), agents have been used to avoid adverse events. The purpose of this article is to outline the adoption and results of a multi-targeted antithrombotic clinical procedure guideline (CPG) for TAH patients. Based on literature review of TAH anticoagulation and multiple case series, a CPG was designed to prescribe the use of multiple pharmacological agents. Total blood loss, Thromboelastograph(®) (TEG), and platelet light-transmission aggregometry (LTA) measurements were conducted on 13 TAH patients during the first 2 weeks of support in our institution. Target values and actual medians for postimplant days 1, 3, 7, and 14 were calculated for kaolinheparinase TEG, kaolin TEG, LTA, and estimated blood loss. Protocol guidelines were followed and anticoagulation management reduced bleeding and prevented thrombus formation as well as thromboembolic events in TAH patients postimplantation. The patients in this study were susceptible to a variety of possible complications such as mechanical device issues, thrombotic events, infection, and bleeding. Among them all it was clear that patients were at most risk for bleeding, particularly on postoperative days 1 through 3. However, bleeding was reduced into postoperative days 3 and 7, indicating that acceptable hemostasis was achieved with the anticoagulation protocol. The multidisciplinary, multi-targeted anticoagulation clinical procedure guideline was successful to maintain adequate antithrombotic therapy for TAH patients.
Honda, N; Inamoto, T; Nogawa, M; Takatani, S
An ultracompact, completely implantable permanent use electromechanical ventricular assist device (VAD) and total artificial heart (TAH) intended for 50-60 kg size patients have been developed. The TAH and VAD share a miniature electromechanical actuator that comprises a DC brushless motor and a planetary roller screw. The rotational force of the motor is converted into the rectilinear force of the roller screw to actuate the blood pump. The TAH is a one piece design with left and right pusher plate type blood pumps sandwiching an electromechanical actuator. The VAD is one half of the TAH with the same actuator but a different pump housing and a backplate. The blood contacting surfaces, including those of the flexing diaphragm and pump housing, of both the VAD and TAH were made of biocompatible polyurethane. The diameter, thickness, volume, and weight of the VAD are 90 mm, 56 mm, 285 cc, and 380 g, respectively, while those of the TAH are 90 mm, 73 mm, 400 cc, and 440 g, respectively. The design stroke volume of both the VAD and TAH is 60 cc with the stroke length being 12 mm. The stroke length and motor speed are controlled solely based on the commutation signals of the motor. An in vitro study revealed that a maximum pump flow of 7.5 L/min can be obtained with a pump rate of 140 bpm against a mean afterload of 100 mm Hg. The power requirement ranged from 4 to 6 W to deliver a 4-5 L/min flow against a 100 mm Hg afterload with the electrical-to-hydraulic efficiency being 19-20%. Our VAD and TAH are the smallest of the currently available devices and suitable for bridge to transplant application as well as for permanent circulatory support of 50-60 kg size patients.
Meyer, A; Slaughter, M
In the 1960s, cardiac surgeons and biomedical engineers pioneered the development of total artificial hearts (TAH) for the treatment of left and right heart failure. As we mark the 10th anniversary of the first implantation of the AbioCor device, the use of TAH has been limited, having failed to reach its envisioned potential and promise as an alternative therapy to heart transplantation. The Syncardia/CardioWest device, originally developed 30 years ago as the Jarvik TAH and later renamed the CardioWest TAH, continues to be used clinically in over 50 centers within the US and Europe having supported over 900 patients worldwide. Syncardia continues to develop TAH technology as evidenced by their recent introduction of a new portable pneumatic driver that enables patients to be discharged from the hospital. In contrast to TAH devices, continuous flow ventricular assist devices (VAD) have made tremendous technological strides and are rapidly gaining widespread clinical acceptance. The VAD technology has demonstrated extraordinary safety and reliability records through evolving technologies, advanced biocompatible materials, and improved patient management. Subsequently, the number of TAH implantations remains low compared to the growth in LVAD implants. Nonetheless, the Syncardia/CardioWest TAH remains an important and viable option for patients with severe biventricular failure and end organ dysfunction. Overall, a 79% survival rate has been achieved in patients supported with a Syncardia/CardioWest TAH as bridge-to-transplantation. In this review article, a brief history on the evolution of TAH devices, their current use and emerging use of evolving continuous flow VAD technology as chronic biventricular and TAH device systems are presented.
Cheng, Allen; Trivedi, Jaimin R; Van Berkel, Victor H; Massey, H Todd; Slaughter, Mark S
The use of left ventricular assist devices (LVAD) has increased significantly in the last decade. However, right heart dysfunction remains a problem despite the improved outcomes with continuous-flow LVADs. Surgical options for bridge to transplantation (BTT) in patients with biventricular failure are total artificial heart (TAH) or biventricular support (BiVAD). This study examines the differences in pre- and post-transplantation outcomes and survival in patients with TAH or BiVAD support as BTT. The United Network of Organ Sharing database was retrospectively queried from January 2005 to December 2014 to identify adult patients undergoing heart transplantation (n = 17,022). Patients supported with either TAH (n = 212) or BiVAD (n = 366) at the time of transplantation were evaluated. Pre- and post-transplantation Kaplan-Meier survival curves were examined. Cox regression model was used to study the hazard ratios of the association between TAH versus BiVAD support and post-transplant survival. The median age of the study groups was 49.8 ± 12.9 (TAH) and 47.2 ± 13.9 (BiVAD) years (range 18-74 years). There were more men, 87% versus 74%, in the TAH group (p < 0.0001) with greater body mass index, 27.3 ± 5.2 versus 25.6 ± 4.7 (p < 0.0001), compared to those with BiVADs. Creatinine was higher, 1.7 + 1.2 versus 1.3 + 0.8 mg/dL (p < 0.0001), in the TAH group before transplant. The 30-day, one-, and three-year post-transplantation survival was 88%, 78%, and 67%, respectively, for patients with TAH support versus 93%, 83%, and 73% (p = 0.06) for patients with BiVAD support. Cox regression model shows pre-transplant creatinine (HR = 1.21, p = 0.008) is associated with a lower post-transplant survival. TAH is not associated with a worse post-transplant survival (p = 0.1). There was no difference in wait-list survival in patients supported with TAH or BiVAD (p = 0.8). Although there has been a recent
Takatani, S; Orime, Y; Tasai, K; Ohara, Y; Naito, K; Mizuguchi, K; Makinouchi, K; Damm, G; Glueck, J; Ling, J
A multipurpose miniature electromechanical energy system has been developed to yield a compact, efficient, durable, and biocompatible total artificial heart (TAH) and ventricular assist device (VAD). Associated controller-driver electronics were recently miniaturized and converted into hybrid circuits. The hybrid controller consists of a microprocessor and controller, motor driver, Hall sensor, and commutation circuit hybrids. The sizing study demonstrated that all these components can be incorporated in the pumping unit of the TAH and VAD, particularly in the centerpiece of the TAH and the motor housing of the VAD. Both TAH and VAD pumping units will start when their power line is connected to either the internal power pack or the external battery unit. As a redundant driving and diagnostic port, an emergency port was newly added and will be placed in subcutaneous location. In case of system failure, the skin will be cut down, and an external motor drive or a pneumatic driver will be connected to this port to run the TAH. This will minimize the circulatory arrest time. Overall efficiency of the TAH without the transcutaneous energy transmission system was 14-18% to deliver pump outputs of 4-9 L/min against the right and left afterload pressures of 25 and 100 mm Hg. The internal power requirement ranged from 6 to 13 W. The rechargeable batteries such as NiCd or NiMH with 1 AH capacity can run the TAH for 30-45 min. The external power requirement, when TETS efficiency of 75% was assumed, ranged from 8 to 18 W. The accelerated endurance test in the 42 degrees C saline bath demonstrated stable performance over 4 months. Long-term endurance and chronic animal studies will continue toward a system with 5 years durability by the year 2000.
Dodd, J.; Kishiyama, C.; Mukainakano, Hiroshi; Nagata, M.; Tsukamoto, H.
A lithium ion cell designed for implantable medical devices was tested for its performance as a power source for left ventricular assist devices (LVAD) or total artificial hearts (TAH). These two cardiovascular devices require high power, and thus a high current (0.5-3 A) and high voltage (20-30 V). Since these are implantable medical devices, in addition to high power capability, the power source should have long cycle life and calendar life, as well as high safety. The QL0700I, a 700 mAh cell, was cycled at 0.5 C rate as well as at 1.5 C rate, and the cycle life capacity retention was evaluated after numerous cycles. A battery pack consisting of seven QL0700I cells in series, with a battery management system (BMS) connected, was tested for rate capability as well as safety protection.
Zimmerman, Hannah; Coehlo-Anderson, Romana; Slepian, Marvin; Smith, Richard G; Sethi, Gulshan; Copeland, Jack G
We report two cases at a single institution, a 52-year-old man and a 25-year-old woman, who had failures of their CardioWest total artificial hearts (TAH) from central venous lines that caused obstruction of the right ventricular inflow valves. Each patient was noted to have decreasing TAH outputs for a few days before this catastrophic device arrest. Both patients died; one suddenly and one during a protracted period, as a result of catheter entrapment of the disc of the Medtronic Hall right ventricular inflow valve.
Kiris, Cetin; Rogers, Stuart; Kwak, Dochan; Chang, I.-DEE
The extension of computational fluid dynamics techniques to artificial heart flow simulations is illustrated. Unsteady incompressible Navier-Stokes equations written in 3-D generalized curvilinear coordinates are solved iteratively at each physical time step until the incompressibility condition is satisfied. The solution method is based on the pseudo compressibility approach and uses an implicit upwind differencing scheme together with the Gauss-Seidel line relaxation method. The efficiency and robustness of the time accurate formulation of the algorithm are tested by computing the flow through model geometries. A channel flow with a moving indentation is computed and validated with experimental measurements and other numerical solutions. In order to handle the geometric complexity and the moving boundary problems, a zonal method and an overlapping grid embedding scheme are used, respectively. Steady state solutions for the flow through a tilting disk heart valve was compared against experimental measurements. Good agreement was obtained. The flow computation during the valve opening and closing is carried out to illustrate the moving boundary capability.
Cohn, William E; Timms, Daniel L; Frazier, O H
A practical artificial heart has been sought for >50 years. An increasing number of people succumb to heart disease each year, but the number of hearts available for transplantation remains small. Early total artificial hearts mimicked the pumping action of the native heart. These positive-displacement pumps could provide adequate haemodynamic support and maintain the human circulation for short periods, but large size and limited durability adversely affected recipients' quality of life. Subsequent research into left ventricular assist devices led to the use of continuous-flow blood pumps with rotating impellers. Researchers have attempted to integrate this technology into modern total artificial hearts with moderate clinical success. The importance of pulsatile circulation remains unclear. Future research is, therefore, needed into positive-displacement and rotary total artificial hearts.
Annas, G J
The author continues his argument against the temporary artificial heart ("The Phoenix heart: what we have to lose," Hastings Center Report 1985 Jun; 15(3): 15-16) with an account of recipient Michael Drummond's experience at the University of Arizona in August 1985. Annas faults the University's informed consent procedure and labels its consent form "misleading, rudimentary, and confusing." He also questions why Drummond was assigned top priority for a human heart after he had received a temporary artificial one. Annas urges a moratorium on permanent artificial hearts because of their devastating effects on recipients, and on temporary devices because they may become permanent. He also argues that there is, as yet, no ethically acceptable way of allocating human hearts to those with artificial hearts, and that the expensive bridge-to-transplant procedure fails to increase the total number of lives saved by heart transplants.
Reich, H J; Morgan, J; Arabia, F; Czer, L; Moriguchi, J; Ramzy, D; Esmailian, F; Lam, L; Dunhill, J; Volod, O
Essentials Bleeding is a major source of morbidity during mechanical circulatory support. von Willebrand factor (VWF) multimer loss may contribute to bleeding. Different patterns of VWF multimer loss were seen with the two device types. This is the first report of total artificial heart associated VWF multimer loss. Background Bleeding remains a challenge during mechanical circulatory support and underlying mechanisms are incompletely understood. Functional von Willebrand factor (VWF) impairment because of loss of high-molecular-weight multimers (MWMs) produces acquired von Willebrand disease (VWD) after left ventricular assist device (LVAD). Little is known about VWF multimers with total artificial hearts (TAHs). Here, VWF profiles with LVADs and TAHs are compared using a VWD panel. Methods VWD evaluations for patients with LVAD or TAH (2013-14) were retrospectively analyzed and included: VWF activity (ristocetin cofactor, VWF:RCo), VWF antigen (VWF:Ag), ratio of VWF:RCo to VWF:Ag, and quantitative VWF multimeric analysis. Results Twelve patients with LVADs and 12 with TAHs underwent VWD evaluation. All had either normal (47.8%) or elevated (52.2%) VWF:RCo, normal (26.1%) or elevated (73.9%) VWF:Ag and 50.0% were disproportional (ratio ≤ 0.7). Multimeric analysis showed abnormal patterns in all patients with LVADs: seven with high MWM loss; five with highest MWM loss. With TAH, 10/12 patients had abnormal patterns: all with highest MWM loss. High MWM loss correlated with presence of LVAD and highest MWM loss with TAH. Increased low MWMs were detected in 22/24. Conclusion Using VWF multimeric analysis, abnormalities after LVAD or TAH were detected that would be missed with measurements of VWF level alone: loss of high MWM predominantly in LVAD, loss of highest MWM in TAH, and elevated levels of low MWM in both. This is the first study to describe TAH-associated highest MWM loss, which may contribute to bleeding. © 2017 International Society on Thrombosis and
The present state of artificial heart research and development is analyzed in light of public perceptions affected by accounts of the experiences of those who received the Jarvik-7. On the assumption that research will continue, it is argued that the therapeutic goals of the artificial heart can be realized, and funding be obtained, only in an atmosphere of positive publicity. To this end, formation of an association of companies involved in artificial heart R & D is recommended. Such a group would articulate voluntary standards and produce reports of advances in the field. Artificial hearts, it is noted in conclusion, have been effective as temporary assist devices in patients destined to receive heart transplants.
Andrade, A; Nicolosi, D; Lucchi, J; Biscegli, J; Arruda, A C; Ohashi, Y; Mueller, J; Tayama, E; Glueck, J; Nosé, Y
Leading international institutions are designing and developing various types of ventricular assist devices (VAD) and total artificial hearts (TAH). Some of the commercially available pulsatile VADs are not readily implantable into the thoracic cavity of smaller size patients because of size limitation. The majority of the TAH dimensions requires the removal of the patients' native heart. A miniaturized artificial heart, the auxiliary total artificial heart (ATAH), is being developed in these authors' laboratories. This device is an electromechanically driven ATAH using a brushless direct current (DC) motor fixed in a center metallic piece. This pusher plate-type ATAH control is based on Frank-Starling's law. The beating frequency is regulated through the change of the left preload, assisting the native heart in obtaining adequate blood flow. With the miniaturization of this pump, the average sized patient can have the surgical implantation procedure in the right thoracic cavity without removing the native heart. The left and right stroke volumes are 35 and 32 ml, respectively. In vitro tests were conducted, and the performance curves demonstrate that the ATAH produces 5 L/min of cardiac output at 180 bpm (10 mmHg of left inlet mean pressure and 100 mm Hg of left outlet mean pressure). Taking into account that this ATAH is working along with the native heart, this output is more than satisfactory for such a device.
Nguyen, A; Pozzi, M; Mastroianni, C; Léger, P; Loisance, D; Pavie, A; Leprince, P; Kirsch, M
Biventricular support can be achieved using paracorporeal ventricular assist devices (p-BiVAD) or the Syncardia temporary total artificial heart (t-TAH). The purpose of the present study was to compare survival and morbidity between these devices. Data from 2 French neighboring hospitals were reviewed. Between 1996 and 2009, 148 patients (67 p-BiVADs and 81 t-TAH) underwent primary, planned biventricular support. There were 128 (86%) males aged 44±13 years. Preoperatively, p-BiVAD recipients had significantly lower systolic and diastolic blood pressures, more severe hepatic cytolysis and higher white blood cell counts than t-TAH recipients. In contrast, t-TAH patients had significantly higher rates of pre-implant ECLS and hemofiltration. Mean support duration was 79±100 days for the p-BiVAD group and 71±92 for t-TAH group (P=0.6). Forty two (63%) p-BiVAD recipients were bridged to transplantation (39, 58%) or recovery (3, 5%), whereas 51 (63%) patients underwent transplantation in the t-TAH group. Death on support was similar between groups (p-BiVAD, 26 (39%); t-TAH, 30 (37%); P=0.87). Survival while on device was not significantly different between patient groups and multivariate analysis showed that only preimplant diastolic blood pressure and alanine amino-transferase levels were significant predictors of death. Post-transplant survival in the p-BiVAD group was 76±7%, 70±8%, and 58±9% at 1, 3, and 5 years after transplantation, respectively, and was similar to that of the t-TAH group (77±6%, 72±6%, and 70±7%, P=0.60). Survival while on support and up to 5 years after heart transplantation was not significantly different in patients supported by p-BiVADs or t-TAH. Multivariate analysis revealed that survival while on transplantation was not affected by the type of device implanted.
Kwak, Dochan; Kiris, Cetin; Feiereisen, William (Technical Monitor)
This paper reports the progress being made towards developing complete blood flow simulation capability in human, especially, in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological characterization of blood. As a first step, computational technology developed for aerospace applications was extended in the recent past to the analysis and development of mechanical devices. The blood flow in these devices is practically incompressible and Newtonian, and thus various incompressible Navier-Stokes solution procedures can be selected depending on the choice of formulations, variables and numerical schemes. Two primitive variable formulations used are discussed as well as the overset grid approach to handle complex moving geometry. This procedure has been applied to several artificial devices. Among these, recent progress made in developing DeBakey axial flow blood pump will be presented from computational point of view. Computational and clinical issues will be discussed in detail as well as additional work needed.
Tatsumi, Eisuke; Taenaka, Yoshiyuki; Homma, Akihiko; Nishinaka, Tomohiro; Takewa, Yoshiaki; Tsukiya, Tomonori; Ohnishi, Hiroyuki; Oshikawa, Mitsuo; Shirakawa, Yukitoshi; Kakuta, Yukihide; Shioya, Kyoko; Katagiri, Nobumasa; Mizuno, Toshihide; Kamimura, Tadayuki; Takano, Hisateru; Tsukahara, Kinji; Tsuchimoto, Katsuya; Wakui, Hideki; Yamaguchi, Hideaki
Electrohydraulic total artificial heart (EHTAH) and electrohydraulic ventricular assist device (EHVAD) systems have been developed in our institute. The EHTAH system comprises a pumping unit consisting of blood pumps and an actuator, as well as an electronic unit consisting of an internal controller, internal and external batteries, and transcutaneous energy transfer (TET) and optical telemetry (TOT) subunits. The actuator, placed outside the pericardial space, reciprocates and delivers hydraulic silicone oil to the alternate blood pumps through a pair of flexible oil conduits. The pumping unit with an external controller was implanted in 10 calves as small as 55 kg. Two animals survived for more than 12 weeks in a good general condition. The assumed cardiac output ranged between 6 and 10 L/min, the power consumption was 12-18 W, and the energy efficiency was estimated to be 9-11%. Initial implantation of subtotal system including electronic units was further conducted in another calf weighing 73 kg. It survived for 3 days with a completely tether free system. The EHVAD system is developed by using the left blood pump and the actuator of the EHTAH, which were packaged in a compact metal casing with a compliance chamber. In vitro testing demonstrated maximum output more than 9 L/min and more than 13% maximum efficiency. The initial animal testing lasted for 25 days. These results indicate that our EHTAH and EHVAD have the potential to be totally implantable systems.
Debaene, P; Aguilera, D; Kertzscher, U; Affeld, K
The walls in blood pumps are made of artificial material and thus are thrombogenic to a lesser or larger degree. Also the flow plays a role: a blood flow with no flow separations and stagnation zones is required to avoid the generation of thrombi. A precondition for solving this problem is the assessment of the wall shear rate. However this parameter is difficult to assess because of the deformability of the walls and the pulsation of the flow. Two methods are proposed to estimate the wall shear stress in bloodpumps. The paint erosion method allows a characterisation of the flow near the wall. The second method is a special development of standard Particle Image Velocimetry (PIV). A vector field of the flow close to the wall results. Both methods should permit the assessment of the wall shear stress in bloodpumps.
Kasirajan, Vigneshwar; Tang, Daniel G; Katlaps, Gundars J; Shah, Keyur B
Treatment options for late-stage biventricular heart failure are limited but include medical therapy with intravenous inotropes, biventricular assist devices (Bi-VADs) and the total artificial heart (TAH). In this manuscript, we review the indications, surgical techniques and outcomes for the TAH. The TAH offers biventricular replacement, rather than 'assistance', as the device is placed orthotopically after excision of the entire ventricular myocardium and all four native valves. In contrast to patients with Bi-VADs, patients with the TAH have no postoperative inotrope requirements, arrhythmias or inflow/outflow cannulae-related complications. Additionally, patients participate in rehabilitation early after device placement and the development of a portable drive may facilitate hospital discharge in the USA. Furthermore, total heart replacement may be ideal for heart failure associated with unique anatomical and mechanical complications. The TAH is an effective therapeutic option for the treatment of patients dying of heart failure who may not be suitable candidates for left ventricular assist devices.
CHF - surgery; Congestive heart failure - surgery; Cardiomyopathy - surgery; HF - surgery; Intra-aortic balloon pumps - heart failure; IABP - heart failure; Catheter based assist devices - heart failure
Ruzza, A; Czer, L S C; Ihnken, K A; Sasevich, M; Trento, A; Ramzy, D; Esmailian, F; Moriguchi, J; Kobashigawa, J; Arabia, F
We present the first single-center report of 2 consecutive cases of combined heart and kidney transplantation after insertion of a total artificial heart (TAH). Both patients had advanced heart failure and developed dialysis-dependent renal failure after implantation of the TAH. The 2 patients underwent successful heart and kidney transplantation, with restoration of normal heart and kidney function. On the basis of this limited experience, we consider TAH a safe and feasible option for bridging carefully selected patients with heart and kidney failure to combined heart and kidney transplantation. Recent FDA approval of the Freedom driver may allow outpatient management at substantial cost savings. The TAH, by virtue of its capability of providing pulsatile flow at 6 to 10 L/min, may be the mechanical circulatory support device most likely to recover patients with marginal renal function and advanced heart failure. Copyright © 2015 Elsevier Inc. All rights reserved.
Pierce, W S; Rosenberg, G; Snyder, A J; Pae, W E; Donachy, J H; Waldhausen, J A
Advances in microelectronics, high-strength magnets, and control system design now make replacement of the heart using an implantable, electrically powered pump feasible. The device described herein is a compact, dual pusher plate unit with valved polyurethane sac-type ventricles positioned at either end. The power unit consists of a small, brushless direct current motor and a motion translator. A microprocessor control system is used to regulate heart beat rate and provide left-right output balance. Bench studies lasting for as long as 1 year have been performed. Heart replacement with the electric heart has been performed in 18 calves since 1984. The longest survivor lived for more than 7 months. Among the causes of termination were component failure, thromboembolic complications, and bleeding. No major problem has been identified that precludes prolonged use of the electric heart. In the future the patient with end-stage heart disease will have an electric artificial heart as one therapeutic option.
Davis, P K; Rosenberg, G; Snyder, A J; Pierce, W S
Pneumatic total artificial heats, although demonstrating utility as temporary mechanical circulatory support devices, have not demonstrated a great deal of promise as permanent cardiac replacements. The increasing number of patients who would be candidates for total heart replacement suggests a large role for a permanent implantable total artificial heart. To that end, the Pennsylvania State University is developing an electric motor-driven total artificial heart; the results with implants in calves are encouraging. In this device, a roller-screw mechanism is used to translate the rotation of a brushless direct-current motor into rectilinear motion of a pusher-plate assembly, which in turn empties the blood sacs. The total artificial heart of the future will function under automatic control without percutaneous leads, and this should provide the patient with a nearly normal life-style. Although further experimental efforts are necessary to prepare the device for clinical trials, the technology to provide a safe and reliable electric blood-pump system is at hand.
Nemeh, Hassan W; Smedira, Nicholas G
Left ventricular assist devices (LVADs) and artificial hearts are improving. These devices can prolong a patient's life while on a heart transplant list. More exciting, mechanical assistance may provide an opportunity for a damaged heart to recover some function. Still, despite the promise, the use of these devices raises some difficult cost-benefit and ethical questions.
Rady, Mohamed Y; Verheijde, Joseph L
Left ventricular assist devices (LVADs) and total artificial hearts (TAHs) are surgically implanted as permanent treatment of unrecoverable heart failure. Both LVADs and TAHs are durable mechanical circulatory support (MCS) devices that can prolong patient survival but also alter end-of-life trajectory. The permissibility of discontinuing assisted circulation is controversial because device deactivation is a life-ending intervention. Durable MCS is intended to successfully replace native physiological functions in heart disease. We posit that the presence of new lethal pathophysiology (ie, a self-perpetuating cascade of abnormal physiological processes causing death) is a central element in evaluating the permissibility of deactivating an LVAD or a TAH. Consensual discontinuation of durable MCS is equivalent with allowing natural death when there is an onset of new lethal pathophysiology that is unrelated to the physiological functions replaced by an LVAD or a TAH. Examples of such lethal conditions include irreversible coma, circulatory shock, overwhelming infections, multiple organ failure, refractory hypoxia, or catastrophic device failure. In all other situations, deactivating the LVAD/TAH is itself the lethal pathophysiology and the proximate cause of death. We postulate that the onset of new lethal pathophysiology is the determinant factor in judging the permissibility of the life-ending discontinuation of a durable MCS.
Ferng, Alice S; Oliva, Isabel; Jokerst, Clinton; Avery, Ryan; Connell, Alana M; Tran, Phat L; Smith, Richard G; Khalpey, Zain
Since the creation of SynCardia's 50 cc Total Artificial Hearts (TAHs), patients with irreversible biventricular failure now have two sizing options. Herein, a case series of three patients who have undergone successful 50 and 70 cc TAH implantation with complete closure of the chest cavity utilizing preoperative "virtual implantation" of different sized devices for surgical planning are presented. Computed tomography (CT) images were used for preoperative planning prior to TAH implantation. Three-dimensional (3D) reconstructions of preoperative chest CT images were generated and both 50 and 70 cc TAHs were virtually implanted into patients' thoracic cavities. During the simulation, the TAHs were projected over the native hearts in a similar position to the actual implantation, and the relationship between the devices and the atria, ventricles, chest wall, and diaphragm were assessed. The 3D reconstructed images and virtual modeling were used to simulate and determine for each patient if the 50 or 70 cc TAH would have a higher likelihood of successful implantation without complications. Subsequently, all three patients received clinical implants of the properly sized TAH based on virtual modeling, and their chest cavities were fully closed. This virtual implantation increases our confidence that the selected TAH will better fit within the thoracic cavity allowing for improved surgical outcome. Clinical implantation of the TAHs showed that our virtual modeling was an effective method for determining the correct fit and sizing of 50 and 70 cc TAHs. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Burch, J. L. (Inventor)
An actuator device is described for moving an artificial leg of a person having a prosthesis replacing an entire leg and hip joint. The device includes a first articulated hip joint assembly carried by the natural leg and a second articulated hip joint assembly carried by the prosthesis whereby energy from the movement of the natural leg is transferred by a compressible fluid from the first hip joint assembly to the second hip joint assembly for moving the artificial leg.
Jonsen, A R
A member of the two federal advisory panels on artificial hearts reflects that the nuclear-powered artificial heart, had it been developed, would have posed a physical threat to others. Today's artificial heart poses a different threat. Because of the high costs, many people may be deprived of access to other forms of medical care and other social goods.
de Mol, Bas A J M; Lahpor, Jaap
An artificial heart is a continuous-flow pump device with a constant output, which usually supports the left ventricle. Over the past five years, survival rates with an artificial heart have increased dramatically, but with an annual mortality of 10% per year compared with 6% for heart transplantation the artificial heart is mainly a 'bridge to transplantation' or an alternative for those patients who are not suitable for heart transplant, 'destination therapy'. It is anticipated that the number and severity of complications will decrease as a result of technological progress. The artificial heart could then become a long-term treatment option providing a good quality of life and thus become equivalent to a heart transplant.
Recent developments in the artificial health program, such as the transplantation of the Jarvik device into Dr. Barney Clark, have prompted a re-evaluation of this technology. Gorovitz discusses the artificial heart in the contexts of patient autonomy and resource allocation. He sees the heart as an example of new medical capabilities that could increase the divergence between the values of physician and patient, and tension between individual interests and the social good. He raises several points to be considered in the debate about the costs and benefits of the heart program, and cautions against prematurely establishing criteria by which to ration artificial hearts.
Boehmer, John P
efficient shape have been under scrutiny for several years. New methods of restraining the heart with prosthetic material are under investigation in humans, with encouraging pilot results. Heart replacement has been evaluated clinically with LV assist devices for several decades. The Randomized Evaluation of Mechanical Assistance Therapy as an Alternative in Congestive Heart Failure (REMATCH) study has demonstrated a proof of concept for the use of mechanical blood pumps to improve survival, functional capacity, and symptoms. Several assist devices with such features as total implantability, improved durability, and smaller size are now under study; these may further improve the outcomes of patients. One year ago, the world witnessed the first clinical use of a totally implantable total artificial heart. Although the long-term outcomes were limited, the device demonstrated an impressive ability to improve organ function and extend survival in the population facing imminent death. Further development in this field is expected. The use of devices in HF now has a strong foothold, and the potential exists for substantially greater use of a broad range of devices in the near future.
Anyanwu, Anelechi; Zucchetta, Fabio; Gerosa, Gino
The SynCardia total artificial heart (TAH) currently provides the most definitive option for patients with biventricular failure who are not candidates for isolated left ventricular (LV) assist device placement. The techniques for implantation are adaptable to almost all patients with advanced heart failure, including those with severe biventricular cardiomyopathy, complex congenital heart disease, failed LV assist devices, failed transplantations, and acquired structural heart defects that have failed or are not amenable to conventional surgical treatment. Over the years, the implantation technique has evolved in order to minimize the surgical invasiveness of the procedure, in anticipation of additional future surgery. Meticulous hemostasis with double layer sutures, use of Gore-Tex sheets around the TAH and the pericardial cavity, and use of tissue expanders to avoid contraction of pericardial cavity around the device are discussed in detail in the following report. Additionally, we will provide our experience with implantation of TAH in various challenging scenarios, such as patients with a small chest cavity, congenital heart defects, and simultaneous use of extracorporeal membrane oxygenation (ECMO). PMID:25512904
Torregrossa, Gianluca; Anyanwu, Anelechi; Zucchetta, Fabio; Gerosa, Gino
The SynCardia total artificial heart (TAH) currently provides the most definitive option for patients with biventricular failure who are not candidates for isolated left ventricular (LV) assist device placement. The techniques for implantation are adaptable to almost all patients with advanced heart failure, including those with severe biventricular cardiomyopathy, complex congenital heart disease, failed LV assist devices, failed transplantations, and acquired structural heart defects that have failed or are not amenable to conventional surgical treatment. Over the years, the implantation technique has evolved in order to minimize the surgical invasiveness of the procedure, in anticipation of additional future surgery. Meticulous hemostasis with double layer sutures, use of Gore-Tex sheets around the TAH and the pericardial cavity, and use of tissue expanders to avoid contraction of pericardial cavity around the device are discussed in detail in the following report. Additionally, we will provide our experience with implantation of TAH in various challenging scenarios, such as patients with a small chest cavity, congenital heart defects, and simultaneous use of extracorporeal membrane oxygenation (ECMO).
Fukamachi, Kiyotaka; Horvath, David J.; Massiello, Alex L.; Fumoto, Hideyuki; Horai, Tetsuya; Rao, Santosh; Golding, Leonard A. R.
Background We are developing a very small, innovative, continuous-flow total artificial heart (CFTAH) that passively self-balances left and right pump flows and atrial pressures without sensors. This report details the CFTAH design concept and our initial in vitro data. Methods System performance of the CFTAH was evaluated using a mock circulatory loop to determine the range of systemic and pulmonary vascular resistances (SVR and PVR) over which the design goal of a maximum absolute atrial pressure difference of 10 mm Hg is achieved for a steady-state flow condition. Pump speed was then modulated at 2,600 ± 900 rpm to induce flow and arterial pressure pulsation to evaluate the effects of speed pulsations on the system performance. An automatic control mode was also evaluated. Results Using only passive self-regulation, pump flows were balanced and absolute atrial pressure differences were maintained below 10 mm Hg over a range of SVR (750-2,750 dyne·sec·cm-5) and PVR (135-600 dyne·sec·cm-5) values far exceeding normal levels. The magnitude of induced speed pulsatility affected relative left/right performance, allowing for an additional active control to improve balanced flow and pressure. The automatic control mode adjusted pump speed to achieve targeted pump flows based on sensorless calculations of SVR and CFTAH flow. Conclusions The initial in vitro testing of the CFTAH with a single, valveless, continuous-flow pump demonstrated its passive self-regulation of flows and atrial pressures and a new automatic control mode. PMID:19782599
Kohli, Harajeshwar S; Canada, Justin; Arena, Ross; Tang, Daniel G; Peberdy, Mary Ann; Harton, Suzanne; Flattery, Maureen; Doolin, Kelly; Katlaps, Gundars J; Hess, Michael L; Kasirajan, Vigneshwar; Shah, Keyur B
The total artificial heart (TAH) consists of two implantable pneumatic pumps that replace the heart and operate at a fixed ejection rate and ejection pressure. We evaluated the blood pressure (BP) response to exercise and exercise performance in patients with a TAH compared to those with a with a continuous-flow left ventricular assist device (LVAD). We conducted a single-center, retrospective study of 37 patients who received a TAH and 12 patients implanted with an LVAD. We measured the BP response during exercise, exercise duration and change in tolerated exercise workload over an 8-week period. In patients with a TAH, baseline BP was 120/69 ± 13/13, exercise BP was 118/72 ± 15/10 and post-exercise BP was 120/72 ± 14/12. Mean arterial BP did not change with exercise in patients with a TAH (88 ± 10 vs 88 ± 11; p = 0.8), but increased in those with an LVAD (87 ± 8 vs 95 ± 13; p < 0.001). Although the mean arterial BP (MAP) was negatively correlated with metabolic equivalents (METs) achieved during exercise, the association was not statistically significant (β = -0.1, p = 0.4). MAP correlated positively with METs achieved in patients with LVADs (MAP: β = 0.26, p = 0.04). Despite the abnormal response to exercise, patients with a TAH participated in physical therapy (median: 5 days; interquartile range [IQR] 4 to 7 days) and treadmill exercise (19 days; IQR: 13 to 35 days) early after device implantation, with increased exercise intensity and duration over time. During circulatory support with a TAH, the BP response to exercise was blunted. However, aerobic exercise training early after device implantation was found to be safe and feasible in a supervised setting. 2011 International Society for Heart and Lung Transplantation. All rights reserved.
Purpose: To describe the total artificial heart (TAH) device as a bridge to heart transplantation (BTT), and related physical therapy management, while comparisons to left ventricular assist devices (LVAD) are made. Summary: The SynCardia CardioWest Temporary TAH System is the only TAH approved by the Food and Drug Administration (FDA), Health Canada and Consultants Europe (CE) for BTT. CardioWest implantation involves cardiectomy thus avoiding pulmonary hypertension, right heart failure, inotropic or anti-arrhythmic agents, myocardial and valve related problems. CardioWest has a fixed beat rate and cardiac output is dependent upon venous return and preload. Both TAH and LVADs are adaptive with exercise, increasing cardiac output during activities, allowing for conditioning to occur peripherally. Left ventricular assist devices have portable drivers permitting discharge home, while the CardioWest's large driver console necessitates inpatient therapy. Exercise progression, positioning, and monitoring of exercise intolerance are similar with LVAD and TAH. Ventricular fill volumes in TAH dictate cardiac output and require close attention. Cardiectomy in TAH prevents electrocardiography, telemetry, and native pulse rate monitoring. Conclusion: While mechanical differences exist between TAH and LVAD, physical therapists can provide evidence-based treatment for patients with TAH using previously established guidelines for patients with heart failure and mechanical circulatory support. PMID:20520759
Adachi, Iki; Morales, David S. L.
In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation. With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification. PMID:25078059
Adachi, Iki; Morales, David S L
In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation. With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.
Yaung, Jill; Arabia, Francisco A; Nurok, Michael
Advanced heart failure continues to be a leading cause of morbidity and mortality despite improvements in pharmacologic therapy. High demand for cardiac transplantation and shortage of donor organs have led to an increase in the utilization of mechanical circulatory support devices. The total artificial heart is an effective biventricular assist device that may be used as a bridge to transplant and that is being studied for destination therapy. This review discusses the history, indications, and perioperative management of the total artificial heart with emphasis on the postoperative concerns.
Rogers, Stewart E.; Kwak, Dochan; Kiris, Cetin; Chang, I-Dee
Report discusses computations of blood flow through prosthetic tilting disk valve. Computational procedure developed in simulation used to design better artificial hearts and valves by reducing or eliminating following adverse flow characteristics: large pressure losses, which prevent hearts from working efficiently; separated and secondary flows, which causes clotting; and high turbulent shear stresses, which damages red blood cells. Report reiterates and expands upon part of NASA technical memorandum "Computed Flow Through an Artificial Heart and Valve" (ARC-12983). Also based partly on research described in "Numerical Simulation of Flow Through an Artificial Heart" (ARC-12478).
Rogers, Stewart E.; Kwak, Dochan; Kiris, Cetin; Chang, I-Dee
Report discusses computations of blood flow through prosthetic tilting disk valve. Computational procedure developed in simulation used to design better artificial hearts and valves by reducing or eliminating following adverse flow characteristics: large pressure losses, which prevent hearts from working efficiently; separated and secondary flows, which causes clotting; and high turbulent shear stresses, which damages red blood cells. Report reiterates and expands upon part of NASA technical memorandum "Computed Flow Through an Artificial Heart and Valve" (ARC-12983). Also based partly on research described in "Numerical Simulation of Flow Through an Artificial Heart" (ARC-12478).
Chronic immunosuppression, allograft coronary disease, and restricted availability of donor organs continue to limit the scope of cardiac transplantation. Meanwhile increasingly favourable experience with implantable blood pumps used as a bridge to transplant has reintroduced the concept of permanent mechanical cardiac support. Existing models (for example, the Thermo Cardiosystems Heartmate device) are now used for such support in patients who are not candidates for transplantation. Miniaturised axial flow pumps such as the Jarvik 2000 fit within the failed left ventricle and provide an exciting prospect for the treatment of heart failure in the future. Preliminary experience suggests that the "offloaded" left ventricle may recover. Mechanical blood pumps can be used before the onset of multisystem failure and removed if the myocardium recovers. This "bridge to recovery" concept should be tested in patients with recoverable cardiomyopathy and those with coronary disease and poor left ventricular function where an implantable pump can be used in conjunction with myocardial revascularisation. Images PMID:8868975
Sunagawa, Gengo; Horvath, David J; Karimov, Jamshid H; Moazami, Nader; Fukamachi, Kiyotaka
A total artificial heart (TAH) is the sole remaining option for patients with biventricular failure who cannot be rescued by left ventricular assist devices (LVADs) alone. However, the pulsatile TAH in clinical use today has limitations: large pump size, unknown durability, required complex anticoagulation regimen, and association with significant postsurgical complications. That pump is noisy; its large pneumatic driving lines traverse the body, with bulky external components for its drivers. Continuous-flow pumps, which caused a paradigm shift in the LVAD field, have already contributed to the rapidly evolving development of TAHs. Novel continuous-flow TAHs are only in preclinical testing or developmental stages. We here review the current state of TAHs, with recommended requirements for the TAH of the future.
Zeng, Hongjun; Jarvik, Robert; Catausan, Grace; Moldovan, Nicolaie; Carlisle, John
Ultrananocrystalline diamond (UNCD), an extremely smooth, low cost diamond coating was successfully developed herein for antithrombogenic application which requires high biocompatibility, low wear, low friction, and chemical inertness. The substrate materials utilized in the Jarvik 2000 ventricular assist device (VAD), silicon carbide and titanium alloy, provide an excellent substrate match for UNCD integration. The paper addresses the development of medical-quality UNCD films to significantly improve the knowledge base regarding the defect mechanisms of UNCD films, to reduce or eliminate known wear-inducing imperfections in the film, and to thoroughly characterize and test the films as well as assembled UNCD-coated VADs. After the defect reduction and seeding experiments to improve film adhesion and coating quality, the best candidate deposition method has been down-selected for coating and assembly of VAD parts from Jarvik Heart. The coated and assembled devices have been tested with mechanical and blood-simulating fluid hydrodynamic testing at Jarvik Heart for full verification of the new coating technology. UNCD interface takes advantage of combining unmatched durability and antithrombogenicity. PMID:27867245
Tozzi, Piergiorgio; Michalis, Alexandre; Hayoz, Daniel; Locca, Didier; von Segesser, Ludwig K
We describe a device made of artificial muscle for the treatment of end-stage heart failure as an alternative to current heart assist devices. The key component is a matrix of nitinol wires and aramidic fibers called Biometal muscle (BM). When heated electrically, it produces a motorless, smooth, and lifelike motion. The BM is connected to a carbon fiber scaffold, tightening the heart and providing simultaneous assistance to the left and right ventricles. A pacemaker-like microprocessor drives the contraction of the BM. We tested the device in a dedicated bench model of diseased heart. It generated a systolic pressure of 75 mm Hg and ejected a maximum of 330 ml/min, with an ejection fraction of 12%. The device required a power supply of 6 V, 250 mA. This could be the beginning of an era in which BMs integrate or replace the mechanical function of natural muscles.
Ghodsizad, Ali; Koerner, Michael M; El-Banayosy, A; Zeriouh, Mohamed; Ruhparwar, Arjang; Loebe, Matthias
The SynCardia Total Artificial Heart (TAH) has been used for patients with biventricular failure, who cannot be managed with implantation of a left ventricular (LV) assist device. Following TAH implantation, our patient developed severe hemolysis, which could only be managed successfully by aggressive blood pressure control [Ohashi 2003; Nakata 1998].
Lubeck, D P
As discussed above, approximately 32,500 persons aged 55 to 70 years with end-stage heart disease may be potential candidates for the artificial heart each year. However, continued application of a protocol that requires informed consent by the patient effectively limits the pool to 12,000 annually. Estimates of the cost of the artificial heart include charges for the surgical procedure, device and console, and continuing medical surveillance. These estimates range from a low of $100,000 to a high of $300,000 per patient in the initial year. Assuming a five-year, 51% survival and an initial cost of $100,000, total program costs in the fifth year are projected to be $1.3 billion for a pool of 12,000 patients, and $3.8 billion for 32,500 patients. These projected costs are associated with anticipated increases in life expectancy. For those individuals destined to develop heart disease, the anticipated average increase is approximately half a year. In comparison, heart transplant patients who meet the surgical criteria but who do not receive a new heart do not survival beyond six months. In an era of limited resources, it is imperative that such a potentially expensive innovation as the artificial heart be compared carefully with other social and medical programs designed to extend life and improve its quality. Such a comparison will require a full understanding of the likely costs and benefits of the device. A viable artificial heart would greatly alter current treatment for end-stage cardiac disease. More patients would benefit from this therapy than currently benefit from heart transplants, and the costs of caring for these patients would increase substantially. The current state of development of the artificial heart provides an opportunity to collect data on investigational artificial heart performance, clinical results, patient status, and economic and social costs. This knowledge base would be invaluable for future technology assessments and policy decisions
Webb, J. A., Jr.; Gebben, V. D.
The factors leading to the design of a controlled driving system for either a heart assist pump or artificial heart are discussed. The system provides square pressure waveform to drive a pneumatic-type blood pump. For assist usage the system uses an R-wave detector circuit that can detect the R-wave of the electrocardiogram in the presence of electrical disturbances. This circuit provides a signal useful for synchronizing an assist pump with the natural heart. It synchronizes a square wave circuit, the output of which is converted into square waveforms of pneumatic pressure suitable for driving both assist device and artificial heart. The pressure levels of the driving waveforms are controlled by means of feedback channels to maintain physiological regulation of the artificial heart's output flow. A more compact system that could achieve similar regulatory characteristics is also discussed.
Artificial heart (AH) study has been started in 1957. After the accomplishments of various difficulties, the AH can become to use clinically as a postcardiotomy cardiac assist or bridge to heart transplantation. However, there remain many obstacles to realize an implantable total artificial heart. The history of AH was the self-making. Although self-making is important in all the experimental sciences, it is the most important factor to develop AH. In this paper, the author would like to introduce the present status of AH and the importance of self-making.
Morris, Rohinton J
End-stage congestive heart failure remains the leading cause of death in the United States. Despite advances in medical treatment, it also remains the most common reason for admission to the hospital. The gold standard of treatment for the failing heart, orthotopic heart transplantation, is limited by a shortage of donor hearts. There are also a significant number of patients who are not transplant candidates due to comorbid conditions and/or inability to tolerate immunosuppressive therapy. To meet the need for this latter group, the medical field has embraced ventricular assist device (VAD) therapy to extend survival and improve quality-of-life for the end-stage cardiac patient. This therapy, however, has been currently limited to the failing left ventricle and is still fraught with complications that limit long-term and widespread use. The total artificial heart, as currently available with two devices, is rapidly becoming the treatment of choice for biventricular failure.
Lin, Yu; Cui, Long
Artificial anus is the important surgical treatment for low colorectal cancer. However, fecal incontinence caused by artificial anus has significant influence on quality of life of patients. A series of novel therapy devices have been invented to solve the problem. According to the different applying methods, these devices can be divided into artificial sphincter and occluder. Artificial sphincter is implanted surgically and more automatic but its complicated design increased risk of complications such as infection and gastrointestinal symptoms. By comparison, occluder is less automatic and needs daily cleaning or replacement, but more comfortable, concealed and safer. For most of occluder are disposable or replaced frequently, advanced devices will greatly increase the economic burden on patients. With the progress of science and technology, artificial anal devices will become more intelligent, automatic and miniaturization.
A national effort to develop a fully implantable artificial heart has included thermal power sources since 1967. Two of seven artificial heart thermal converter programs funded by the National Institutes of Health (NIH) and/or the Department of Energy (DOE) remain active. The technical requirements for an implantable engine with a ten year maintenance-free operating life represent perhaps the most demanding application ever considered for Stirling engines. Existing hardware versions of engines from the two continuing programs have recorded impressive performance and lifetime data. Pending versions are expected to meet all the stringent operating requirements and eventually be qualified for use in humans. The artificial heart thermal power source program provides a unique forum for meaningful comparison of innovative and conventional Stirling engine concepts in an arena of professionally executed advanced technology programs which in aggregate represent more than forty million dollars in developmental funding.
THEORETICAL DESIGN CONSIDERATIONS AND PHYSIOLOGIC PERFORMANCE CRITERIA FOR AN IMPROVED INTRACORPOREAL (ABDOMINAL) ELECTRICALLY ACTUATED LONG-TERM LEFT VENTRICULAR ASSIST DEVICE (“E-TYPE” ALVAD) OR PARTIAL ARTIFICIAL HEART
Igo, Stephen R.; Hibbs, C. Wayne; Fuqua, John M.; Trono, Ruben; Edmonds, Charles H.; Norman, John C.
Our laboratories are engaged in the design of a clinically-oriented electrically actuated long-term intracorporeal (abdominal) left ventricular assist device (“E-type” ALVAD) or partial artificial heart. This infradiaphragmatic blood pump is designed to be powered by implantable electrical to mechanical energy converter systems. The following analyses were undertaken to: [List: see text] The proposed “E-type” ALVAD should be capable of pumping 4-7 liters per minute at heart rates of 75-100 beats per minute during rest, and 10 liters per minute at rates of 120 beats per minute during moderate exercise. These performance levels should be exceeded with a maximum device stroke volume of 85-90 ml and a mean pump inflow (filling) impedance of ≤ 0.072 gm/sec/cm−5. Images PMID:15216070
Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P
SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329
Shumakov, V I; Griaznov, G M; Zhemchuzhnikov, G N; Kiselev, I M; Osipov, A P
An atomic artificial heart for orthotopic implantation was developed with the following characteristics: volume, 1.2 L; weight, 1.5 kg; radioisotope power, 45 W; operating life, up to 5 years; hemodynamics, similar to natural hemodynamics. The artificial heart includes a thermal drive with systems for regulating power, feeding steam into the cylinders, return of the condensate to the steam generator, and delivery of power to the ventricles and heat container. The artificial heart is placed in an artificial pericardium partially filled with physiologic solution. It uses a steam engine with two operating cylinders that separately drive the left and right ventricles. There is no electronic control system in the proposed design. The operation of the heat engine is controlled, with preservation of autoregulation by the vascular system of the body. The separate drives for the ventricles is of primary importance as it provides for operation of the artificial heart through control of cardiac activity by venous return. Experimental testing on a hydromechanical bench demonstrated effective autoregulation.
Chung, J; Lee, J H; Choi, J; Lee, J; Kim, W G; Sun, K; Min, B G
The availability of a remote management system, which provides both physiological-related information about the patient and device-related information about the implanted device, would be helpful during in vivo experiments or clinical trials involving artificial heart implantation. In order to be able to monitor the course of the in vivo experiment continuously regardless of the patient's location, an internet-based remote monitoring system was developed, which can monitor physiological-related information such as pressure (AoP, LAP, RAP, PAP) and flow data, as well as device-related information such as current, direction and pump operating conditions. The home care artificial heart monitoring system which we developed consists of four main components, which are the transcutaneous information transmission system (TITS), local monitoring station (LMS), data server station (DSS), and client monitoring station (CMS). The device-related information and physiological-related information can be transmitted in real time from a patient in a remote non-clinical environment to the specialist situated in a clinic depending on the current capabilities and availability of the internet. The local monitoring station situated at the remote site is composed of a data acquisition and preprocessing unit connected to a computer via its RS-232 port, and which communicate using a Java-based client-server architecture. The remote monitoring system so developed was used during an in vivo experiment of the artificial heart implantation for 2 months and performed successfully according to design specifications.
Khan, Sanna; Jehangir, Waqas
The heart is a muscular organ which pumps blood through blood vessels to different organs of the body. It is the most significant and vital organ in the human body. Without this organ, life is unimaginable. Doctors and scientists have been trying for a long time to create something similar or equivalent to the heart. The purpose is to develop a temporary machine or pump for a person who has a disease of the heart and their survival without transplant is impossible. These temporary devices can provide enough time for the patient until a donor heart is available. The purpose of this review is to provide an overview and history of how man has developed an artificial heart for survival.
Khan, Sanna; Jehangir, Waqas
The heart is a muscular organ which pumps blood through blood vessels to different organs of the body. It is the most significant and vital organ in the human body. Without this organ, life is unimaginable. Doctors and scientists have been trying for a long time to create something similar or equivalent to the heart. The purpose is to develop a temporary machine or pump for a person who has a disease of the heart and their survival without transplant is impossible. These temporary devices can provide enough time for the patient until a donor heart is available. The purpose of this review is to provide an overview and history of how man has developed an artificial heart for survival. PMID:28348709
Gerosa, Gino; Gallo, Michele; Bottio, Tomaso; Tarzia, Vincenzo
The CardioWest Total Artificial Heart (CW-TAH) has been approved as a temporary device for bridge to cardiac transplantation and is under investigation for destination therapy by US Food and Drug Administration (FDA). We herein report the longest worldwide survival out of hospital (1374 days) of a patient supported with Cardio West Total Artificial Heart (CW-TAH). This experience is intended as a proof of concept of using CW-TAH as the destination therapy in patients with biventricular failure. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
Perrodin, Stéphanie F; Muller, Olivier; Gronchi, Fabrizio; Liaudet, Lucas; Hullin, Roger; Kirsch, Matthias
We report the use of a total extracorporeal heart for uncontrolled bleeding following a proximal left anterior descending artery perforation, using two centrifugal ventricular assist devices after heart explantation. The literature describing similar techniques and patient outcomes for this "bailout" technique are reviewed. © 2017 Wiley Periodicals, Inc.
Glyantsev, Sergey P; Tchantchaleishvili, Vakhtang; Bockeria, Leo A
The world's first implantable total artificial heart was designed by Vladimir Demikhov as a fourth year biology student in Voronezh, Soviet Union, in 1937. As a prototype of his device, Demikhov must have used an apparatus for extracorporeal blood circulation invented by Sergei Bryukhonenko of Moscow. The device was the size of a dog's native heart and consisted of two diaphragm pumps brought into motion by an electric motor. A dog with an implanted device lived for 2.5 hours. In addition to having the prototype, the preconditions for Demikhov's artificial heart creation were his manual dexterity, expertise in animal physiology, and his mechanistic worldview.
Rogers, Stuart E.; Kwak, Dochan; Kiris, Cetin; Chang, I-Dee
NASA technical memorandum discusses computations of flow of blood through artificial heart and through tilting-disk artificial heart valve. Represents further progress in research described in "Numerical Simulation of Flow Through an Artificial Heart" (ARC-12478). One purpose of research to exploit advanced techniques of computational fluid dynamics and capabilities of supercomputers to gain understanding of complicated internal flows of viscous, essentially incompressible fluids like blood. Another to use understanding to design better artificial hearts and valves.
Arabia, Francisco A; Moriguchi, Jaime D
The medical/surgical management of advanced heart failure has evolved rapidly over the last few decades. With better understanding of heart failure pathophysiology, new pharmacological agents have been introduced that have resulted in improvements in survival. For those patients that fail to improve, mechanical circulatory support with left ventricular assist devices and total artificial hearts (TAHs) have served as a beneficial bridge to transplantation. The TAH has continued to play a significant role as a bridge to transplantation in patients with biventricular failure and more selected indications that could not be completely helped with left ventricular assist devices. Improved survival with the TAH has resulted in more patients benefiting from this technology. Improvements will eventually lead to a totally implantable device that will permanently replace the failing human heart.
Gopalan, Radha; Scott, Robert; Arabia, Francisco; Chandrasekaran, Krishnaswamy
Interaction between the electrical system of implanted cardiovascular devices and electrical stimulation of acupuncture points (electro-acupuncture) can be life-threatening. As a result, there is reluctance to use this modality in patients who have been implanted with any cardiac device. A patient with a total artificial heart was successfully treated with electro-acupuncture for inflammatory arthritis without any adverse events. This case illustrates the safety of electro-acupuncture in patients with a total artificial heart.
Mussivand, T; Hendry, P J; Masters, R G; Holmes, K S; Hum, A; Keon, W J
An intrathoracic pulsatile artificial heart pump has been developed. Transcutaneous energy transfer and biotelemetry systems provide continuous power and remote monitoring and control, with no percutaneous connections required. The electrohydraulic system can be used either as a ventricular assist device or with modifications as a total artificial heart. The device uses a unidirectional axial flow pump coupled with a pressure activated one-way valve to allow hydraulic fluid to passively return to the volume displacement chamber during diastole. The transcutaneous energy transfer system provides power to the device and recharges the implantable battery pack. A wearable external controller and external battery pack provide the patient enhanced mobility and thus an improved quality of life. The biotelemetry system allows control and monitoring of the device after implantation, as well as an added capability to monitor and control the device remotely over public communication lines. Early prototypes have functioned failure free for up to 3 years in vitro. The device has sustained circulation in vivo for up to 4 days. Design optimization is continuing, and chronic in vivo evaluation is planned.
Kaufmann, R; Reul, H; Rau, G
To perform the first experimental tests for validation of a new gear unit concept, the pump chamber, diaphragm, and pusher plate design of an orthotopic electromechanical total artificial heart (TAH) (Helmholtz Labtype) was manufactured. In its early stage of development, it provides some of the most important features of the conceptual final artificial heart. The new gear unit transforms a uniform unidirectional rotational motor movement into translatory pusher plate movements, with resting phase in the end-diastolic position, and the angled pump chamber orientation determines the available space for the motor and gear unit. Furthermore, this labtype provides flexibility with regard to use of different types of structural parts for experimental investigations. The first in vitro test results, obtained with specially designed circulatory mockloops that simulate physiological preload and afterload conditions, are presented. They comprise pressure and flow generation, motor performance, efficiency, and energy consumption. The results prove the feasibility of the new gear unit concept for an electromechanical artificial heart and allow a reliable determination of the necessary performance of the future brushless DC motor for the first in vivo TAH model.
Copeland, Jack G; Copeland, Hannah; Gustafson, Monica; Mineburg, Nicole; Covington, Diane; Smith, Richard G; Friedman, Mark
The SynCardia Total Artificial Heart (SynCardia Systems Inc, Tucson, Ariz) has been used as a bridge to cardiac transplantation in 930 patients worldwide and in 101 patients in our program. Our experience with SynCardia Total Artificial Heart implantation documents its indications, safety, and efficacy. Data regarding preoperative condition, mortality, and morbidity have been reviewed and analyzed. From January 1993 to December 2009, 101 patients had bridge to transplant procedures with the SynCardia Total Artificial Heart. Ninety-one percent of cases were Interagency Registry for Mechanically Assisted Circulatory Support profile 1, and the remaining 9% of cases were failing medical therapy on multiple inotropic medications. The mean support time was 87 days (median, 53 days; range, 1-441 days). Pump outputs during support were 7 to 9 L/min. Adverse events included strokes in 7.9% of cases and take-back for hemorrhage in 24.7% of cases. Survival to transplantation was 68.3%. Causes of death of 32 patients on device support included multiple organ failure (13), pulmonary failure (6), and neurologic injury (4). Survival after transplantation at 1, 5, and 10 years was 76.8%, 60.5%, and 41.2%, respectively. The longest-term survivor is currently alive 16.4 years postimplantation. These patients were not candidates for left ventricular assist device therapy and were expected to die. The SynCardia Total Artificial Heart offers a real alternative for survival with a reasonable complication rate in appropriate candidates who otherwise might have been assigned to hospice care. Copyright Â© 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.
Dimitriou, Alexandros Merkourios; Dapunt, Otto; Knez, Igor; Wasler, Andrae; Oberwalder, Peter; Koerfer, Reiner; Tenderich, Gero; Spiliopoulos, Sotirios
Congestive hepatopathy (CH) and acute liver failure (ALF) are common among biventricular heart failure patients. We sought to evaluate the impact of total artificial heart (TAH) therapy on hepatic function and associated clinical outcomes. A total of 31 patients received a Syncardia Total Artificial Heart. Preoperatively 17 patients exhibited normal liver function or mild hepatic derangements that were clinically insignificant and did not qualify as acute or chronic liver failure, 5 patients exhibited ALF and 9 various hepatic derangements owing to CH. Liver associated mortality and postoperative course of liver values were prospectively documented and retrospectively analyzed. Liver associated mortality in normal liver function, ALF and CH cases was 0%, 20% (P=0.03) and 44.4% (P=0.0008) respectively. 1/17 (5.8%) patients with a normal liver function developed an ALF, 4/5 (80%) patients with an ALF experienced a markedly improvement of hepatic function and 6/9 (66.6%) patients with CH a significant deterioration. TAH therapy results in recovery of hepatic function in ALF cases. Patients with CH prior to surgery form a high risk group with increased liver associated mortality.
Harada, Y.; Goto, E. )
This article describes a new approach of Josephson devices for computer applications. With an artificial neural network scheme Josephson devices is expected to develop a new paradigm for future computer systems. Here the authors discuss circuit configuration for a neuron with Josephson devices. The authors proposed a combination of a variable bias source and Josephson devices for a synapse circuit. The bias source signal is steered by the Josephson device input signal and becomes the synapse output signal. These output signals are summed up at the specific resistor or inductor to produce the weighted sum of Josephson devices input signals. According to the error signal, the bias source value is corrected. This corresponds to the learning procedure.
Snyder, A; Rosenberg, G; Weiss, W; Pierce, W; Pae, W; Marlotte, J; Nazarian, R; Ford, S
The authors developed, built, and tested in vivo a completely implanted total artificial heart (TAH) system. The system used a reduced size version of a roller screw energy converter and mating sac blood pumps. The motor drive, pumps, and a compliance chamber were implanted intrathoracically. A canister containing controlling electronics and an emergency battery was implanted in the abdomen. The secondary coil of an inductive energy transmission and telemetry system was placed over the ribs. The system was implanted in three calves, that survived 0.5-13 days with the system. The system maintained safe left atrial pressures and adequate cardiac outputs during each animal's entire course.
Karimov, Jamshid H; Sunagawa, Gengo; Such, Kimberly A; Sale, Shiva; Golding, Leonard A R; Moazami, Nader; Fukamachi, Kiyotaka
The biocompatibility assessment of the Cleveland Clinic continuous-flow total artificial heart is an important part of the device developmental program. Surgical and postoperative management are key factors in achieving optimal outcomes. However, the presence of vascular anatomical abnormalities in experimental animal models is often unpredictable and may worsen the expected outcomes. We report a technical impediment encountered during total artificial heart implantation complicated by unfavorable bovine anatomy of the ascending aorta and brachiocephalic arterial trunk.
Crosby, Jessica R; DeCook, Katrina J; Tran, Phat L; Betterton, Edward; Smith, Richard G; Larson, Douglas F; Khalpey, Zain I; Burkhoff, Daniel; Slepian, Marvin J
With the growth and diversity of mechanical circulatory support (MCS) systems entering clinical use, a need exists for a robust mock circulation system capable of reliably emulating and reproducing physiologic as well as pathophysiologic states for use in MCS training and inter-device comparison. We report on the development of such a platform utilizing the SynCardia Total Artificial Heart and a modified Donovan Mock Circulation System, capable of being driven at normal and reduced output. With this platform, clinically relevant heart failure hemodynamics could be reliably reproduced as evidenced by elevated left atrial pressure (+112%), reduced aortic flow (-12.6%), blunted Starling-like behavior, and increased afterload sensitivity when compared with normal function. Similarly, pressure-volume relationships demonstrated enhanced sensitivity to afterload and decreased Starling-like behavior in the heart failure model. Lastly, the platform was configured to allow the easy addition of a left ventricular assist device (HeartMate II at 9600 RPM), which upon insertion resulted in improvement of hemodynamics. The present configuration has the potential to serve as a viable system for training and research, aimed at fostering safe and effective MCS device use. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Davis, P K; Pae, W E; Pierce, W S
The number of patients who would be candidates for replacement of their failing native heart with an artificial device increases every year. A multidisciplinary group at The Pennsylvania State University is working toward the development of a reliable, totally implantable artificial heart. Initial work resulted in a pneumatic total artificial heart that has performed well in animal implants and has been used clinically in three patients as a temporary bridge to cardiac transplantation. Although pneumatic total artificial hearts have demonstrated utility as temporary mechanical circulatory support devices, attempts at permanent implantation by other groups have been fraught with complications. Because of the suboptimal performance of the pneumatic devices used for permanent implantation, the authors' groups at Penn State is developing n electric motor-driven total artificial heart with encouraging results in calf implants. This artificial heart of the future will use a transcutaneous energy transmission system that will obviate the need for percutaneous lines. Thus, the patient will be provided with as near a normal life-style as possible. At present the technology is at hand to implant an electric blood pump system that should provide a reasonable life-style and function reliably with minimal care. Ongoing cooperative experimental efforts will help to provide the answers necessary to make this system ready for clinical use.
Villa, Chet R; Morales, David L S
The development of durable ventricular assist devices (VADs) has improved mortality rates and quality of life in patients with end stage heart failure. While the use of VADs has increased dramatically in recent years, there is limited experience with VAD implantation in patients with complex congenital heart disease (CHD), despite the fact that the number of patients with end stage CHD has grown due to improvements in surgical and medical care. VAD use has been limited in patients with CHD and end stage heart failure due to anatomic (systemic right ventricle, single ventricle, surgically altered anatomy, valve dysfunction, etc.) and physiologic constraints (diastolic dysfunction). The total artificial heart (TAH), which has right and left sided pumps that can be arranged in a variety of orientations, can accommodate the anatomic variation present in CHD patients. This review provides an overview of the potential use of the TAH in patients with CHD.
Villa, Chet R.; Morales, David L. S.
The development of durable ventricular assist devices (VADs) has improved mortality rates and quality of life in patients with end stage heart failure. While the use of VADs has increased dramatically in recent years, there is limited experience with VAD implantation in patients with complex congenital heart disease (CHD), despite the fact that the number of patients with end stage CHD has grown due to improvements in surgical and medical care. VAD use has been limited in patients with CHD and end stage heart failure due to anatomic (systemic right ventricle, single ventricle, surgically altered anatomy, valve dysfunction, etc.) and physiologic constraints (diastolic dysfunction). The total artificial heart (TAH), which has right and left sided pumps that can be arranged in a variety of orientations, can accommodate the anatomic variation present in CHD patients. This review provides an overview of the potential use of the TAH in patients with CHD. PMID:28536530
Anderson, Eric; Jaroszewski, Dawn; Pierce, Christopher; DeValeria, Patrick; Arabia, Francisco
Circulatory assist devices are an increasingly common method of treating patients with refractory cardiogenic shock. We describe a patient who was a heart transplant candidate with biventricular failure who underwent CardioWest total artificial heart-temporary (SynCardia Inc, Tucson, AZ) implantation with extracorporeal membrane oxygenation to manage the patient's subsequent respiratory failure. After respiratory and hemodynamic stabilization, the CardioWest total artificial heart-temporary served as a successful 62-day bridge-to-heart transplantation.
Jaroszewski, Dawn E; Pierce, Christopher C; Staley, Linda L; Wong, Raymond; Scott, Robert R; Steidley, Eric E; Gopalan, Radha S; DeValeria, Patrick; Lanza, Louis; Mulligan, David; Arabia, Francisco A
End-stage renal failure is often considered a relative contraindication for total artificial heart implantation due to the increased risk of mortality after transplantation. We report the successful treatment of a patient having heart and renal failure with the CardioWest (SynCardia Inc, Tucson, AZ) total artificial heart for bridge-to-cardiac transplantation of a heart and kidney.
Steifer, T.; Lewandowski, M.; Karwat, P.; Gawlikowski, M.
In spite of the progress in material engineering and ventricular assist devices construction, thromboembolism remains the most crucial problem in mechanical heart supporting systems. Therefore, the ability to monitor the patient's blood for clot formation should be considered an important factor in development of heart supporting systems. The well-known methods for automatic embolus detection are based on the monitoring of the ultrasound Doppler signal. A working system utilizing ultrasound Doppler is being developed for the purpose of flow estimation and emboli detection in the clinical artificial heart ReligaHeart EXT. Thesystem will be based on the existing dual channel multi-gate Doppler device with RF digital processing. A specially developed clamp-on cannula probe, equipped with 2 - 4 MHz piezoceramic transducers, enables easy system setup. We present the issuesrelated to the development of automatic emboli detection via Doppler measurements. We consider several algorithms for the flow estimation and emboli detection. We discuss their efficiency and confront them with the requirements of our experimental setup. Theoretical considerations are then met with preliminary experimental findings from a) flow studies with blood mimicking fluid and b) in-vitro flow studies with animal blood. Finally, we discuss some more methodological issues - we consider several possible approaches to the problem of verification of the accuracy of the detection system.
Topaz, S R; Flinders, T; Topaz, H A; Jones, D
The concept of an electrically powered total artificial heart has been pursued by Dr. Kolff and his associates since the 1960s. Since the 1980s these efforts have been concentrated upon the development of the electrohydraulic total artificial heart, a turbine pump powered by a brushless DC motor. Dr. Kolff realized the benefits of pulsatile flow and device response to Starling's Law, and these concepts have formed the basis of subsequent design decisions. Design iterations have both solved existing problems and exposed new challenges. The current device design is greatly improved over early attempts due to the incorporation of technologies that have recently become available as the result of progress in the fields of materials and electronics and due to the lessons learned over many years of research under the guidance of Dr. Kolff. This article describes, from its inception, the last major research project of Dr. Kolff prior to his retirement. The discussion centers around development, problems and their solutions, and the reasoning for given solutions.
Amao, Yutaka; Shuto, Naho; Furuno, Kana; Obata, Asami; Fuchino, Yoshiko; Uemura, Keiko; Kajino, Tsutomu; Sekito, Takeshi; Iwai, Satoshi; Miyamoto, Yasushi; Matsuda, Masatoshi
Solar fuels, such as hydrogen gas produced from water and methanol produced from carbon dioxide reduction by artificial photosynthesis, have received considerable attention. In natural leaves the photosynthetic proteins are well-organized in the thylakoid membrane. To develop an artificial leaf device for solar low-carbon fuel production from CO2, a chlorophyll derivative chlorin-e6 (Chl-e6; photosensitizer), 1-carboxylundecanoyl-1'-methyl-4,4'-bipyrizinium bromide, iodide (CH3V(CH2)9COOH; the electron carrier) and formate dehydrogenase (FDH) (the catalyst) immobilised onto a silica-gel-based thin layer chromatography plate (the Chl-V-FDH device) was investigated. From luminescence spectroscopy measurements, the photoexcited triplet state of Chl-e6 was quenched by the CH3V(CH2)9COOH moiety on the device, indicating the photoinduced electron transfer from the photoexcited triplet state of Chl-e6 to the CH3V(CH2)9COOH moiety. When the CO2-saturated sample solution containing NADPH (the electron donor) was flowed onto the Chl-V-FDH device under visible light irradiation, the formic acid concentration increased with increasing irradiation time.
Johnson, K E; Prieto, M; Joyce, L D; Pritzker, M; Emery, R W
Several models of total artificial hearts have been used for transient or permanent circulatory support in patients with decompensation. The most successful and widely used device, however, has been the Symbion total artificial heart. From Dec. 12, 1982, to Jan. 1, 1991, 180 Symbion total artificial hearts were implanted in 176 patients in 28 centers. Five patients received a Symbion total artificial heart as a permanent circulatory support device, whereas 171 patients received the device as a bridge to heart transplantation. Of the 175 bridge devices (171 patients) 141 were Symbion J7-70 hearts and 34 were Symbion J7-100 hearts. Four patients received two total artificial hearts, the second one after the failure of a transplanted heart because of either rejection (two patients) or donor heart failure (2 patients). Most of the recipients were males (152). The age was 42 +/- 12 years (mean +/- SD) with a weight of 74 +/- 14 kg. The most common indications for implantation included deterioration while awaiting heart transplant (36%) and acute cardiogenic shock (32%). The cause of heart disease was primarily ischemic (52%) and idiopathic (35%) cardiomyopathy. Duration of implantation ranged from 0 to 603 days (mean 25 +/- 64 days). One hundred three (60%) patients had the device less than 2 weeks, 37 (22%) between 2 to 4 weeks and 31 (18%) more than 4 weeks. Complications during implantation included infection (37%), thromboembolic events (stroke 7%, transient ischemic attack 4%), kidney failure requiring dialysis (20%), bleeding requiring intervention (26%), and device malfunction (4%). Of the 171 patients, 118 (69%) underwent orthotopic heart transplantation. Actuarial survival for all patients with implants was 62% for 30 days and 42% for 1 year, and for patients with transplants was 72% for 30 days and 57% for 1 year. The main causes of death were sepsis (33%), multiorgan failure (21%), and posttransplant rejection (10%). The results indicate a relative success of
Spiliopoulos, Sotirios; Dimitriou, Alexandros Merkourios; Guersoy, Dilek; Koerfer, Reiner; Tenderich, Gero
The 50-cc SynCardia total artificial heart is designed to facilitate orthotopic replacement of the native ventricles in patients with a body surface area below 1.7 m(2) in need of long-term circulatory support as a result of end-stage biventricular heart failure. We describe the implementation of this technology in a female patient with irreversible cardiogenic shock on the grounds of acute myocardial infarction and chronic ischemic cardiomyopathy. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
Li, Sai; Kang, Wang; Huang, Yangqi; Zhang, Xichao; Zhou, Yan; Zhao, Weisheng
Neuromorphic computing, inspired by the biological nervous system, has attracted considerable attention. Intensive research has been conducted in this field for developing artificial synapses and neurons, attempting to mimic the behaviors of biological synapses and neurons, which are two basic elements of a human brain. Recently, magnetic skyrmions have been investigated as promising candidates in neuromorphic computing design owing to their topologically protected particle-like behaviors, nanoscale size and low driving current density. In one of our previous studies, a skyrmion-based artificial synapse was proposed, with which both short-term plasticity and long-term potentiation functions have been demonstrated. In this work, we further report on a skyrmion-based artificial neuron by exploiting the tunable current-driven skyrmion motion dynamics, mimicking the leaky-integrate-fire function of a biological neuron. With a simple single-device implementation, this proposed artificial neuron may enable us to build a dense and energy-efficient spiking neuromorphic computing system.
Gerosa, Gino; Scuri, Silvia; Iop, Laura; Torregrossa, Gianluca
Due to shortages in donor organ availability, advanced heart-failure patients are at high risk of further decompensation and often death while awaiting transplantation. This shortage has led to the development of effective mechanical circulatory support (MCS). Currently, various implantable ventricular-assist devices (VADs) are able to provide temporary or long-term circulatory support for many end-stage heart-failure patients. Implantation of a total artificial heart (TAH) currently represents the surgical treatment option for patients requiring biventricular MCS as a bridge to transplant (BTT) or destination therapy (DT). However, the clinical applicability of available versions of positive displacement pumps is limited by their size and associated complications. Application of advanced technology is aimed at solving some of these issues, attempting to develop a new generation of smaller and more effective TAHs to suit a wider patient population. Particular targets for improvement include modifications to the biocompatibility of device designs and materials in order to decrease hemorrhagic and thromboembolic complications. Meanwhile, new systems to power implanted driving units which are fully operational without interruption of skin barriers represent a potential means of decreasing the risk of infections. In this review, we will discuss the history of the TAH, its development and clinical application, the implications of the existing technological solutions, published outcomes and the future outlook for TAHs.
Gerosa, Gino; Scuri, Silvia; Iop, Laura
Due to shortages in donor organ availability, advanced heart-failure patients are at high risk of further decompensation and often death while awaiting transplantation. This shortage has led to the development of effective mechanical circulatory support (MCS). Currently, various implantable ventricular-assist devices (VADs) are able to provide temporary or long-term circulatory support for many end-stage heart-failure patients. Implantation of a total artificial heart (TAH) currently represents the surgical treatment option for patients requiring biventricular MCS as a bridge to transplant (BTT) or destination therapy (DT). However, the clinical applicability of available versions of positive displacement pumps is limited by their size and associated complications. Application of advanced technology is aimed at solving some of these issues, attempting to develop a new generation of smaller and more effective TAHs to suit a wider patient population. Particular targets for improvement include modifications to the biocompatibility of device designs and materials in order to decrease hemorrhagic and thromboembolic complications. Meanwhile, new systems to power implanted driving units which are fully operational without interruption of skin barriers represent a potential means of decreasing the risk of infections. In this review, we will discuss the history of the TAH, its development and clinical application, the implications of the existing technological solutions, published outcomes and the future outlook for TAHs. PMID:25512901
Rogers, Stuart; Kutler, Paul; Kwak, Dochan; Kiris, Centin
Research in both artificial hearts and fluid dynamics benefits from computational studies. Algorithm that implements Navier-Stokes equations of flow extended to simulate flow of viscous, incompressible blood through articifial heart. Ability to compute details of such flow important for two reasons: internal flows with moving boundaries of academic interest in their own right, and many of deficiencies of artificial hearts attributable to dynamics of flow.
Rowles, J R; Khanwilkar, P S; Diegel, P D; Hansen, A C; Bearnson, G B; Smith, K D; Tatsumi, E; Olsen, D B
The first generation of an integrated, totally implantable electrohydraulic total artificial heart was designed for long-term cardiac replacement. The system consists of an elliptical blood pump with an interatrial shunt, Medtronic-Hall 27 mm and 25 mm inflow and outflow valves, respectively, an energy converter consisting of an axial-flow, hydraulic pump driven by a brushless DC motor, and an electronics system with transcutaneous energy transmission and telemetry. Energy is supplied by internal nickel-cadmium rechargeable batteries that supply power for 20 min and external silver-zinc batteries that are designed to supply energy to run the system for 5 hr. The blood pump consists of a single layer diaphragm cast from Biolon, with joined right and left ventricles sharing a common base. The dynamic stroke volume is 84 ml, and maximum cardiac output is 9.2 L/min at a heart rate of 110 beats/min on the mock circulation. A 4.3 mm diameter interatrial shunt is used to balance the volumetrically coupled ventricles. The energy converter pumps hydraulic fluid alternately between ventricles, with controlled, active filling in one ventricle during the systolic phase of the other ventricle. Internal or external controllers adjust the heart rate and motor speed to maintain normal atrial filling pressures and full stroke. Electromagnetic induction is used to transfer energy through the skin and a bidirectional infrared data link incorporated within the transcutaneous energy transmission coils is used to transmit information. The entire system is being assembled and refined for long-term animal implant studies.
Karimov, Jamshid H; Horvath, David J; Okano, Shinji; Goodin, Mark; Sunagawa, Gengo; Byram, Nicole; Moazami, Nader; Golding, Leonard A R; Fukamachi, Kiyotaka
The development of total artificial heart devices is a complex undertaking that includes chronic biocompatibility assessment of the device. It is considered particularly important to assess whether device design and features can be compatible long term in a biological environment. As part of the development program for the Cleveland Clinic continuous-flow total artificial heart (CFTAH), we evaluated the device for signs of thrombosis and biological material deposition in four animals that had achieved the intended 14-, 30-, or 90-day durations in each respective experiment. Explanted CFTAHs were analyzed for possible clot buildup at "susceptible" areas inside the pump, particularly the right pump impeller. Depositions of various consistency and shapes were observed. We here report our findings, along with macroscopic and microscopic analysis post explant, and provide computational fluid dynamics data with its potential implications for thrombus formation. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Stanley, T H; Kennard, L; Isern-Amaral, J; Olsen, D; Lunn, J
Plasma and urine epinephrine and norepinephrine concentrations were measured before and after implantation of an artificial heart in 20 calves and before and after thoracotomy in 3 control calves. All animals had similar preoperative plasma and urine catecholamine concentrations. During the first 4 postoperative days, plasma and urine epinephrine and norepinephrine concentrations were markedly elevated in all animals. However, calves with an artificial heart had significantly higher concentrations than control calves. Thereafter, catecholamine levels in control animals returned to preoperative levels, whereas epinephrine concentrations in artificial heart recipients remained elevated for 2 weeks and norepinephrine concentrations remained elevated for over a month. Two artifical heart recipeints survived longer than 2 months and had normal plasma and urine catecholamine concentrations from day 32 until a few days before being put to death. Although the mechanism in unclear, these findings suggest that early artificial heart function is associated with a significant metabolic stress which slowly disappears or becomes tolerable after one month.
Copeland, Jack G; Smith, Richard G; Bose, Raj K; Tsau, Pei H; Nolan, Paul E; Slepian, Marvin J
Safety and efficacy studies of various mechanical circulatory support devices are important, but may not be strictly comparable. Lacking prospective randomized studies for different devices, we believe that comparison of risk factor analyses may give the surgeon a tool more powerful than current studies for matching a patient with an appropriate device. In this paper, we report risk factor profiles for bridge to transplantation with the CardioWest total artificial heart and summarize reports for other devices. A multiinstitutional risk factor analysis of the CardioWest total artificial heart, as a bridge to transplantation in 81 patients, was conducted. Univariate analyses were performed on 43 preimplantation prognostic factors. From this group, eight factors were chosen for multivariate analysis. Our results were compared with all recent risk factor analyses for other devices. Independent predictors for death at three intervals by multivariate analysis were as follows: "implant to transplant": history of smoking (odds ratio, 34); "implant to 30 days after transplant": history of smoking (odds ratio, 10.00), prothrombin time greater than 16 seconds (odds ratio, 4.76); and "implant to 1 year after transplant": prothrombin time greater than 16 seconds (odds ratio, 3.85). The major difference between this experience and multiple reported experiences with left ventricular assist devices is that for left ventricular assist devices, but not for the temporary CardioWest total artificial heart, right heart failure, high central venous pressure, and being on a ventilator (with or without sepsis) were independent predictors of mortality. Risk factors for bridge to transplantation with the CardioWest total artificial heart are different from those reported for left ventricular assist devices. Recognition of these risk factor differences may facilitate appropriate device selection.
Abe, Y; Chinzei, T; Imachi, K; Mabuchi, K; Atsumi, K; Fujimasa, I
An artificial heart (AH) driving system, in which a sac or diaphragm type blood pump is liquid gas driven, is designed. The working mechanism of this system is as follows: 1) liquid gas is used for the driving source; 2) a liquid gas is stored in its liquid state in the circuit; 3) a liquid gas is vaporized, and the vaporizing pressure squeezes the blood pump, causing ejection of blood; 4) vaporized gas is aspirated and compressed by a small compressor to liquefaction through the heat exchanger, then negative pressure is applied to the blood pump and blood is aspirated; and 5) the blood pump is driven in this closed cycle. To demonstrate the mechanism of this system, a prototype was developed using Freon 114 as the liquid gas. In this system, the maximum flow of the AH at a 100 pulse per minute rate, was about 6.9 L/min, using a 90 ml sac type blood pump. The advantages of this AH driving mechanism are as follows: 1) a small system is available because pressure chambers are not necessary; 2) a biventricular system is available, with a single compressor; 3) no compliance chamber is necessary if the system is small enough to be implanted.
Lee, S H; Choi, W W; Min, B G
Using a one chip microcontroller, 87C196 (One chip EPROM), and an erasable and programmable logic device (EPLD), an implantable control system to drive a pendulum type electromechanical total artificial heart was developed. This control system consists of four parts: a main management system, a motor driver with power regulator, a state monitoring system, and a communication portion. The main system has a speed detector, proportional and integral (PI) control, pulse width modulation (PWM) generation, serial communication, and an analog data processor. Two kinds of power system are used, separated by eight photocoupler arrays to improve system stability. When the performance of each compartment was compared with that of the previously used Z80 microprocessor based control system, good correspondence was shown. Logic power consumption was reduced to one third that of the previous controller. Using mock circulation tests, the overall performance of the control system was evaluated.
Prasad, Amit; Singbartl, Kai; Boone, Jacqueline; Soleimani, Behzad; Zeriouh, Mohamad; Loebe, M; Koerner, Michael; Oei, J Elisabeth; Brehm, Christoph E; Ghodsizad, Ali
As a bridge to transplant, the Syncardia™ total artificial heart (TAH) is an option for patients who are not candidates for left ventricular assist devices (LVAD) due to right ventricular failure. The need for nutritional support in these patients is essential for a favorable outcome. Low body mass indexes and albumin levels have been associated with increased morbidity and mortality in cardiac surgery patients [Alverdy 2003]. It is not uncommon for postoperative patients to have difficulty in consuming enough calories after surgery, which is further complicated by a hypermetabolic demand due to surgical stress. Enteral nutrition has typically been favored for gut mucosal integrity and bacterial flora [Alverdy 2003] [Engleman 1999]. We describe the need for prolonged enteral nutritional support in a TAH patient that was accomplished with a percutaneous endoscopic gastrostomy (PEG) tube.
Kung, R T; Yu, L S; Ochs, B D; Parnis, S M; Macris, M P; Frazier, O H
The ABIOMED implantable total artificial hearts in the final phase of engineering development. The system has a compact electrohydraulically driven energy converter sandwiched between two blood pumps, an internal electronics pack, an internal battery, a transcutaneous energy transmission coil for power transmission, and external wearable electronics pack and battery. The current effort is to complete development of the system during 1996 in preparation for formal pre clinical testing of the device. In vivo studies with the current thoracic unit (ABH II) have achieved 108 days of survival verifying the thermal, physiologic, and hematologic compatibility of the system. The abdominal implantable electronics pack showed no thermal dissipation problem. System improvements include scaling down the size of the thoracic unit, and efficiency enhancement in the power and hybrid electronics. The new system (ABH III) retains the flow capacity of greater than 10 L/min. Size reduction results in an atrial to sternal dimension that would fit 98% and 75% of men and women, respectively.
Thanavaro, Kristin L; Tang, Daniel G; Kasirajan, Vigneshwar; Shah, Keyur B
The total artificial heart (TAH) is effective for bridging patients with biventricular heart failure (BiVHF) to transplantation. It consists of two pneumatic pumps with four mechanical valves that replace nearly the entire myocardium, thus also making it effective therapy for heart failure from alternative (ALT) anatomical and pathophysiological causes that preclude left ventricular assist device (LVAD). This report reviews the clinical indications and outcomes for TAH implantation at our institution from 2006 to 2012. We sought to characterize and compare survival to transplant for patients with BiVHF to those with ALT indications. The overall survival to transplant for all patients was 86% (57/66). There was a trend towards decreased survival to transplantation in the ALT group compared with the BiVHF group (77% vs. 93%, HR 0.42 [95% confidence interval 0.1, 1.7], log-rank test: p = 0.2). This was likely driven by certain high risk subgroups of allograft failure, LVAD failure, and acute postinfarct shock.
Tolpekin, V E; Shumakov, D V
The article summarizes forty-year experience in working over the problem of the artificial heart and auxiliary blood circulation in Laboratory and later Research Institute of Transplantology and Artificial Organs. This work has resulted in the development of balloon pumps for intraaortic contrapulsation, the technique of balloon installation, and indications to its application. The results of the clinical application of the method in patients with various pathologies have been estimated. Preclinically, left ventricular bypass techniques have been tested on more than twenty models of membrane type artificial ventricles. The results of the clinical application of left ventricular bypass have been analyzed. The authors adduce data on the development of the thermomechanical implantable bypass system "Micron-M". After achieving 100-day survival of calves with an artificial heart, an artificial heart with external power supply was used as a "bridge" to heart transplantation, but there was only one patient in whom transplantation was performed. The authors consider development of implantable auxiliary blood circulation devices and the artificial heart to be of great prospective value.
Strüber, Martin; Meyer, Anna L; Malehsa, Doris; Kugler, Christiane; Simon, Andre R; Haverich, Axel
In view of the major technical advances in ventricular assist devices (VAD) in recent years, the authors discuss the question whether these "artificial hearts" are still no more than a temporary measure for patients awaiting heart transplantation (HTx), or whether they can already be used as an independent form of long-term treatment. Statistics from Eurotransplant regarding heart transplantations and transplant waiting lists in Germany are presented. Technical developments in cardiac support systems, the variation in results depending on the indication, and the findings with respect to quality of life are all discussed on the basis of a selective review of the literature and the authors' own clinical experience. The waiting list for heart transplantation in Germany has grown to a record size of nearly 800 patients, while fewer than 400 hearts are transplanted each year. Technical advances have improved outcomes in VAD therapy, but the outcome depends on the patient's preoperative condition. The physical performance of patients who have received VAD is comparable to that of HTx patients; nonetheless, HTx patients have a better quality of life. Chronic VAD therapy has become a clinical reality. Because of the greater number of patients awaiting HTx, many will not receive their transplants in time. When the decision to treat with VAD is made early, it can be used as an alternative form of treatment with a comparable one-year survival (>75%).
Hosseinian, Leila; Levin, Matthew A; Fischer, Gregory W; Anyanwu, Anelechi C; Torregrossa, Gianluca; Evans, Adam S
The Total Artificial Heart (Syncardia, Tucson, AZ) is approved for use as a bridge-to-transplant or destination therapy in patients who have irreversible end-stage biventricular heart failure. We present a unique case, in which the inferior vena cava compression by a total artificial heart was initially masked for days by the concurrent placement of an extracorporeal membrane oxygenation cannula. This is the case of a 33-year-old man admitted to our institution with recurrent episodes of ventricular tachycardia requiring emergent total artificial heart and venovenous extracorporeal membrane oxygenation placement. This interesting scenario highlights the importance for critical care physicians to have an understanding of exact anatomical localization of a total artificial heart, extracorporeal membrane oxygenation, and their potential interactions. In total artificial heart patients with hemodynamic compromise or reduced device filling, consideration should always be given to venous inflow compression, particularly in those with smaller body surface area. Transesophageal echocardiogram is a readily available diagnostic tool that must be considered standard of care, not only in the operating room but also in the ICU, when dealing with this complex subpopulation of cardiac patients.
Sueshiro, M; Fukunaga, S; Mitsui, N; Hirai, S; Koura, Y; Hotei, H; Sueda, T; Katsuhara, K; Matsuura, Y; Koguchi, S
Working toward a completely implantable total artificial heart, we have designed an eccentric roller type total artificial heart. The actuator of this artificial heart is a drum type eccentric roller that squeezes the blood chambers. The blood chambers are made of silicone rubber and are torus in shape. The shape of the artificial heart is an almost circular cylinder, and its length and diameter are 10 cm and 8 cm, respectively. The 2 main characteristics of this artificial heart are that it discharges blood in a pulsatile mode and that it requires no reversing of the motor. Because we have not completed the artificial heart yet, we have tested the eccentric roller mechanism on the prototype with an overflow type mock circulation with a 100 mm Hg afterload. The prototype worked at the roller speeds of 50, 100, and 150 rpm with flow rates of 1.7, 3.7, and 5.4 L/min, respectively. Next the prototype was connected to a Donovan type mock circulatory system and worked at roller speeds of 88-214 rpm with flow rates of 3.0-8.4 L/min against mean afterloads of 82-120 mm Hg.
Wells, Dennis; Villa, Chet R; Simón Morales, David Luís
While use of the total artificial heart (TAH) is growing, the use of the device is not uniform across the gender and age spectrum because the vast majority of implants are in adult males. SynCardia has recently developed a smaller 50 cc TAH that was designed to accommodate patients with a body surface area as low as 1.2 m(2) (potentially even lower using virtual implantation). Herein, we describe the early use of the 50 cc TAH (10 implants in the US and 18 outside the US). Twenty-eight devices have been implanted worldwide. Nineteen (68%) patients were female, 4 (14%) were 21 years of age or younger, and 2 (7%) had a diagnosis of congenital heart disease (1 Fontan). The smallest patient, by body surface area, was 1.35 m(2). Six patients (21%) have been placed on the Freedom Driver, all of whom have survived. Fourteen patients (50%) have had a positive outcome to date. The development of the 50 cc TAH has expanded the population of patients who may benefit from TAH support and thus may help improve outcomes for patients who have had limited biventricular support options to date. Copyright © 2017 Elsevier Inc. All rights reserved.
Mazur, Daniel J; Fuchs, Daniel J; Abicht, Travis O; Peabody, Terrance D
Infection of artificial joint replacements and heart valves is an uncommon but serious complication encountered anytime after the implantation of these prostheses. It is known that bacteremia can lead to infection of a prosthetic device. However, there is no strong evidence to correlate urologic procedures with the development of periprosthetic joint infection or prosthetic valve endocarditis. Therefore, antibiotic prophylaxis for the prevention of endocarditis is not recommended in patients undergoing urologic procedures. However, guidelines regarding prophylaxis to prevent infection of an artificial joint in the setting of a genitourinary procedure are more varied. Copyright © 2015 Elsevier Inc. All rights reserved.
Wojtara, Tytus; Sasaki, Makoto; Konosu, Hitoshi; Yamashita, Masashi; Shimoda, Shingo; Alnajjar, Fady; Kimura, Hidenori
The evolutionarily novel ability to keep ones body upright while standing or walking, the human balance, deteriorates in old age or can be compromised after accidents or brain surgeries. With the aged society, age related balance problems are on the rise. Persons with balance problems are more likely to fall during their everyday life routines. Especially in elderly, falls can lead to bone fractures making the patient bedridden, weakening the body and making it more prone to other diseases. Health care expenses for a fall patient are often very high. There is a great deal of research being done on exoskeletons and power assists. However, these technologies concentrate mainly on the amplifications of human muscle power while balance has to be provided by the human themself. Our research has been focused on supporting human balance in harmony with the human's own posture control mechanisms such as postural reflexes. This paper proposes an artificial balancer that supports human balance through acceleration of a flywheel attached to the body. Appropriate correcting torques are generated through our device based on the measurements of body deflections. We have carried out experiments with test persons standing on a platform subject to lateral perturbations and ambulatory experiments while walking on a balance beam. These experiments have demonstrated the effectiveness of our device in supporting balance and the possibility of enhancing balance-keeping capability in human beings through the application of external torque.
Copeland, J G; Smith, R; Icenogle, T; Vasu, A; Rhenman, B; Williams, R; Cleavinger, M
A detailed summary of seven patients who received eight total artificial heart implants, including one Phoenix heart, two Jarvik 7-100 ml hearts, and five Jarvik 7-70 ml hearts, and nine heart transplants, reveals that bleeding, hemolysis, and thromboembolic and infectious problems are not the limiting factors. Size of the patient and the requirement for adequate space to permit adequate systemic and pulmonary venous filling seem to be the major limitations. Patients with a reasonable expectation of receiving a transplantation within 3 weeks are the best candidates for a bridge to transplantation. After this adhesions were found to cause severe technical problems at reoperation.
Gregory, Shaun D; Loechel, Nicole; Pearcy, Mark J; Fraser, John; Parnis, Steven; Cohn, William E; Timms, Daniel
Successful anatomic fitting of a total artificial heart (TAH) is vital to achieve optimal pump hemodynamics after device implantation. Although many anatomic fitting studies have been completed in humans prior to clinical trials, few reports exist that detail the experience in animals for in vivo device evaluation. Optimal hemodynamics are crucial throughout the in vivo phase to direct design iterations and ultimately validate device performance prior to pivotal human trials. In vivo evaluation in a sheep model allows a realistically sized representation of a smaller patient, for which smaller third-generation TAHs have the potential to treat. Our study aimed to assess the anatomic fit of a single device rotary TAH in sheep prior to animal trials and to use the data to develop a three-dimensional, computer-aided design (CAD)-operated anatomic fitting tool for future TAH development. Following excision of the native ventricles above the atrio-ventricular groove, a prototype TAH was inserted within the chest cavity of six sheep (28-40 kg). Adjustable rods representing inlet and outlet conduits were oriented toward the center of each atrial chamber and the great vessels, with conduit lengths and angles recorded for future analysis. A three-dimensional, CAD-operated anatomic fitting tool was then developed, based on the results of this study, and used to determine the inflow and outflow conduit orientation of the TAH. The mean diameters of the sheep left atrium, right atrium, aorta, and pulmonary artery were 39, 33, 12, and 11 mm, respectively. The center-to-center distance and outer-edge-to-outer-edge distance between the atria, found to be 39 ± 9 mm and 72 ± 17 mm in this study, were identified as the most critical geometries for successful TAH connection. This geometric constraint restricts the maximum separation allowable between left and right inlet ports of a TAH to ensure successful alignment within the available atrial circumference. © 2013
Nomoto, Koichi; Weiner, Menachem M; Evans, Adam
Our case illustrates a patient who suffered a pulmonary artery rupture despite previous total artificial heart implantation and replacement with orthotopic heart transplant. Pulmonary artery rupture during or following cardiac surgery has been reported to occur due to both pulmonary artery catheter use and surgical technique. Our case is the first to demonstrate the occurrence of this complication in the total artificial heart patient population.
Ensor, Christopher R; Cahoon, William D; Crouch, Michael A; Katlaps, Gundars J; Hess, Michael L; Cooke, Richard H; Gunnerson, Kyle J; Kasirajan, Vigneshwar
The CardioWest temporary total artificial heart serves as a viable bridge to orthotopic heart transplantation in patients who are experiencing end-stage refractory biventricular heart failure. This device is associated with a low, albeit still substantial, risk of thrombosis. Platelet interactions with artificial surfaces are complex and result in continuous activation of contact proteins despite therapeutic anticoagulation. We searched the medical literature (publication dates, January 1962-October 2009) in order to evaluate means of mitigating adverse events that have occurred after implantation of the CardioWest temporary total artificial heart.We conclude that the use of a multitargeted antithrombotic approach, involving anticoagulation (bivalirudin and warfarin) and antiplatelet therapy (dipyridamole and aspirin), can mitigate the procoagulative effects of mechanical circulatory assist devices, particularly those that are associated with the CardioWest temporary total artificial heart. Careful monitoring with use of a variant multisystem approach, involving efficacy tests (thrombelastography and light transmittance aggregometry), safety tests (laboratory analyses), and warfarin genomics, may maximize the therapeutic actions and minimize the bleeding risks that are associated with the multitargeted antithrombotic approach. The development and monitoring of individualized antithrombotic regimens require that informed health professionals appreciate the complexities and grasp the hazards that are associated with these therapies.
Cha, Sungdeok; Jeong, Sehun; Yoo, Junbeom; Kim, Young-Gab
Software is being used more frequently to control medical devices such as artificial heart or robotic surgery system. While much of software safety issues in such systems are similar to other safety-critical systems (e.g., nuclear power plants), domain-specific properties may warrant development of customized techniques to demonstrate fitness of the system on patients. In this paper, we report results of a preliminary analysis done on software controlling a Hybrid Ventricular Assist Device (H-VAD) developed by Korea Artificial Organ Centre (KAOC). It is a state-of-the-art artificial heart which completed animal testing phase. We performed software testing in in-vitro experiments and animal experiments. An abnormal behaviour, never detected during extensive in-vitro analysis and animal testing, was found.
Hermsen, Joshua L; Smith, Jason W; Pal, Jay D; Mahr, Claudius; Masri, S Carolina; Dardas, Todd F; Cheng, Richard K; Mokadam, Nahush A
Mechanical circulatory support for heart failure, including the Total Artificial Heart (TAH, Syncardia, Tucson, AZ, USA) has increased in recent years. This report describes bleeding complications associated with the device. A single institution prospectively maintained quality improvement database was reviewed encompassing the first year of clinical experience with the TAH. Patients who underwent TAH implantation were identified, and a review of complications and outcomes was undertaken. Ten patients underwent TAH implant. Four patients experienced delayed postoperative bleeding. In three patients the manifestation of bleeding was tamponade and evidenced by TAH decreased cardiac output. In two patients, at postoperative days 31 and 137, there was a partial disruption of the aortic anastomosis along the outer curvature with pseudoaneurysm formation. Both were repaired by primary suture closure, without use of cardiopulmonary bypass. There was no mortality attributable to bleeding. TAH patients are at risk for delayed postoperative bleeding, often manifest as an acute decrease in cardiac output. Due to pulsatility and high dP/dT, bleeding from the aortic anastomosis should be considered in the differential of a patient with low flow and/or tamponade. © 2015 Wiley Periodicals, Inc.
DeMartino, Erin S; Wordingham, Sara E; Stulak, John M; Boilson, Barry A; Fuechtmann, Kayla R; Singh, Nausheen; Sulmasy, Daniel P; Pajaro, Octavio E; Mueller, Paul S
To describe the characteristics of patients who undergo withdrawal of total artificial heart support and to explore the ethical aspects of withdrawing this life-sustaining treatment. We retrospectively reviewed the medical records of all adult recipients of a total artificial heart at Mayo Clinic from the program's inception in 2007 through June 30, 2015. Management of other life-sustaining therapies, approach to end-of-life decision making, engagement of ethics and palliative care consultation, and causes of death were analyzed. Of 47 total artificial heart recipients, 14 patients or their surrogates (30%) requested withdrawal of total artificial heart support. No request was denied by treatment teams. All 14 patients were supported with at least 1 other life-sustaining therapy. Only 1 patient was able to participate in decision making. It is widely held to be ethically permissible to withdraw a life-sustaining treatment when the treatment no longer meets the patient's health care-related goals (ie, the burdens outweigh the benefits). These data suggest that some patients, surrogates, physicians, and other care providers believe that this principle extends to the withdrawal of total artificial heart support. Copyright © 2017 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.
Samak, Mostafa; Fatullayev, Javid; Sabashnikov, Anton; Zeriouh, Mohamed; Rahmanian, Parwis B.; Choi, Yeong-Hoon; Wippermann, Jens; Wahlers, Thorsten; Schmack, Bastian; Ruhparwar, Arjang; Dohmen, Pascal M.; Karck, Matthias; Popov, Aron-Frederik; Simon, André R.; Weymann, Alexander
The totally artificial heart (TAH) is among the most prominent medical innovations of the 21st century, especially due to the increasing population with end-stage heart failure. The progressive course of the disease, its resistance to conventional therapy, and the scarcity of hearts available for transplantation were the prime impetus for developing a TAH, especially when other options of mechanical circulatory assist devices are exhausted. In this review, we narrate the history of TAH, give an overview of its technology, and address the pros and cons of the currently available TAH models in light of published clinical experience. PMID:26343363
Samak, Mostafa; Fatullayev, Javid; Sabashnikov, Anton; Zeriouh, Mohamed; Rahmanian, Parwis B; Choi, Yeong-Hoon; Wippermann, Jens; Wahlers, Thorsten; Schmack, Bastian; Ruhparwar, Arjang; Dohmen, Pascal M; Karck, Matthias; Popov, Aron-Frederik; Simon, André R; Weymann, Alexander
The totally artificial heart (TAH) is among the most prominent medical innovations of the 21st century, especially due to the increasing population with end-stage heart failure. The progressive course of the disease, its resistance to conventional therapy, and the scarcity of hearts available for transplantation were the prime impetus for developing a TAH, especially when other options of mechanical circulatory assist devices are exhausted. In this review, we narrate the history of TAH, give an overview of its technology, and address the pros and cons of the currently available TAH models in light of published clinical experience.
Roussel, Jean Christian; Sénage, Thomas; Baron, Olivier; Périgaud, Christian; Habash, Oussama; Rigal, Jean Christophe; Treilhaud, Michèle; Trochu, Jean Noel; Despins, Philippe; Duveau, Daniel
When implanted in patients with biventricular failure, the CardioWest total artificial heart has asserted itself over time as a reliable bridge-to-transplant device that as yet is used by only a few international teams. The aim of this single-center retrospective study is to assess both the comorbidity and survival of patients awaiting heart transplants while receiving circulatory support with a CardioWest total artificial heart. From 1990 to December 2006, 42 patients received a CardioWest total artificial heart at our center. Mean age at the time of implantation was 45.7 +/- 9.5 years, and 40 patients (95%) were men. Idiopathic or dilated cardiomyopathy was diagnosed in 45.2% (n = 19) of the patients and ischemic cardiomyopathy in 42.8% (n = 18). Average body surface area was 1.9 +/- 0.22 m(2). Duration of support was 1 to 292 days (mean, 101 +/- 86 days). Twelve patients died (28.5%) while receiving device support, and 30 patients (71.5%) underwent transplantation. Actuarial survival rates for the transplanted patients were 90% (n = 25), 81% (n = 14), and 76% (n = 10) at 1, 5, and 10 years, respectively. Causes of death during device support included multiorgan failure in 6 (50%), sepsis in 2, acute respiratory distress syndrome in 2, alveolar hemorrhage in 1, and other cause in 1. There were no device malfunctions that led to patient death. Adverse events included stroke in 3 patients (7%) and infections in 35 patients (85%) during support. The CardioWest total artificial heart is an excellent bridge-to-transplant device for patients with biventricular failure. Our study demonstrates excellent safety, reliability, and efficiency. Exceptional outcome after transplantation underlines its capacity to aid in end-organ recovery.
Gebben, V. D.; Webb, J. A., Jr.
Inexpensive industrial pneumatic components are combined to produce control system to drive sac-type heart-assistance blood pump with controlled pulsatile pressure that makes pump rate of flow sensitive to venous /atrial/ pressure, while stroke is centered about set operating point and pump is synchronized with natural heart.
Donovan, F M
A major problem in improving artificial heart designs is the absence of methods for accurate in vitro testing of artificial heart systems. A mock circulatory system has been constructed which hydraulically simulates the systemic and pulmonary circulations of the normal human. The device is constructed of 1/2 in. acrylic sheet and has overall dimensions of 24 in. wide, 16 in. tall, and 8 in. deep. The artificial heart to be tested is attached to the front of the device, and pumps fluid from the systemic venous chamber into the pulmonary arterial chamber and from the pulmonary venous chamber into the systemic arterial chamber. Each of the four chambers is hermetically sealed. The compliance of each chamber is determined by the volume of air trapped above the fluid in that chamber. The pulmonary and systemic resistances are set automatically by bellows-operated valves to simulate the barroreceptor response in the systemic arteries and the passive pulmonary resistance response in the pulmonary arteries. Cardiac output is measured by a turbine flowmeter in the systemic circulation. Results using the Kwan-Gett artificial heart show a good comparison between the mock circulatory system response and the calf response.
Spiliopoulos, Sotirios; Dimitriou, Alexandros Merkourios; Serrano, Maria Rosario; Guersoy, Dilek; Autschbach, Ruediger; Goetzenich, Andreas; Koerfer, Reiner; Tenderich, Gero
Coagulation disorders and an immune-altered state are common among total artificial heart patients. In this context, we sought to evaluate the safety of percutaneous dilatational tracheostomy in cases of prolonged need for mechanical ventilatory support. We retrospectively analysed the charts of 11 total artificial heart patients who received percutaneous dilatational tracheostomy. We focused on early and late complications. We observed no major complications and no procedure-related deaths. Early minor complications included venous oozing (45.4%) and one case of local infection. Late complications, including subglottic stenosis, stomal infection or infections of the lower respiratory tract, were not observed. In conclusion, percutaneous dilatational tracheostomy in total artificial heart patients is safe. Considering the well-known benefits of early tracheotomy over prolonged translaryngeal intubation, we advocate early timing of therapy in cases of prolonged mechanical ventilation. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
Bramstedt, Katrina A.
Total artificial heart technology as a potential clinical therapy raises the issue of elective device inactivation in both futile and non-futile situations. This article explores elective device inactivation in non-futile situations. In reply to such requests for inactivation, the medical team should reflect on the individual's decision-making…
Bramstedt, Katrina A.
Total artificial heart technology as a potential clinical therapy raises the issue of elective device inactivation in both futile and non-futile situations. This article explores elective device inactivation in non-futile situations. In reply to such requests for inactivation, the medical team should reflect on the individual's decision-making…
Li, Qilei; Yang, Ming; Ou, Wenchu; Meng, Fan; Xu, Zihao; Xu, Liang
The purpose of this paper is to achieve a measurement of temperature prediction for artificial heart without sensor, for which the research briefly describes the application of back propagation neural network as well as the optimized, by genetic algorithm, BP network. Owing to the limit of environment after the artificial heart implanted, detectable parameters out of body are taken advantage of to predict the working temperature of the pump. Lastly, contrast is made to demonstrate the prediction result between BP neural network and genetically optimized BP network, by which indicates that the probability is 1.84% with the margin of error more than 1%.
Latrémouille, Christian; Duveau, Daniel; Cholley, Bernard; Zilberstein, Luca; Belbis, Guillaume; Boughenou, Marie-Fazia; Meleard, Denis; Bruneval, Patrick; Adam, Clovis; Neuschwander, Arthur; Perles, Jean-Christophe; Jansen, Piet; Carpentier, Alain
The Carmat bioprosthetic total artificial heart (TAH) contains bioprosthetic blood-contacting surfaces, and is designed for orthotopic cardiac replacement. In preparation for clinical studies, we evaluated the TAH performance and its effects on end-organ function in an animal model. Twelve female Charolais calves, 2-3 months of age and weighing 102-122 kg, were implanted with the TAH through a mid-sternotomy to ensure an adequate anatomic fit. The intended support duration was 4-10 days. Haematological values, creatinine, bilirubin and lactate levels were measured and mean arterial and central venous pressure, central venous oxygen saturation and TAH parameters were monitored. The calves were placed in a cage immediately postoperatively, and extubated on postoperative day 1 in most cases. Average support duration was 3 days, with 4 of 12 calves supported for 4, 4, 8 and 10 days. The initial procedures were used to refine surgical techniques and postoperative care. Pump output ranged from 7.3 to 10 l/min. Haemodynamic parameters and blood analysis were within acceptable ranges. No device failures occurred. No anticoagulation was used in the postoperative phase. The calves were euthanized in case of discomfort compromising the animal well-being, such as respiratory dysfunction, severe blood loss and cerebral dysfunction. Device explant analysis showed no thrombus formation inside the blood cavities. Histological examination of kidneys showed isolated micro-infarction in 2/12 animals; brain histology revealed no thromboembolic depositions. The Carmat bioprosthetic TAH implanted in calves up to 10 days provided adequate blood flow to organs and tissues. Low levels of haemolysis and no visible evidence of thromboembolic depositions in major organs and device cavities, without the use of anticoagulation, may indicate early-phase haemocompatibility of the TAH. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio
Domestic and foreign trends in the prevalence of heart failure and the necessity of next-generation artificial hearts: a survey by the Working Group on Establishment of Assessment Guidelines for Next-Generation Artificial Heart Systems.
Tatsumi, Eisuke; Nakatani, Takeshi; Imachi, Kou; Umezu, Mitsuo; Kyo, Shun-Ei; Sase, Kazuhiro; Takatani, Setsuo; Matsuda, Hikaru
A series of guidelines for development and assessment of next-generation medical devices has been drafted under an interagency collaborative project by the Ministry of Health, Labor and Welfare and the Ministry of Economy, Trade and Industry. The working group for assessment guidelines of next-generation artificial hearts reviewed the trend in the prevalence of heart failure and examined the potential usefulness of such devices in Japan and in other countries as a fundamental part of the process of establishing appropriate guidelines. At present, more than 23 million people suffer from heart failure in developed countries, including Japan. Although Japan currently has the lowest mortality from heart failure among those countries, the number of patients is gradually increasing as our lifestyle becomes more Westernized; the associated medical expenses are rapidly growing. The number of heart transplantations, however, is limited due to the overwhelming shortage of donor hearts, not only in Japan but worldwide. Meanwhile, clinical studies and surveys have revealed that the major causes of death in patients undergoing long-term use of ventricular assist devices (VADs) were infection, thrombosis, and mechanical failure, all of which are typical of VADs. It is therefore of urgent and universal necessity to develop next-generation artificial hearts that have excellent durability to provide at least 2 years of event-free operation with a superior quality of life and that can be used for destination therapy to save patients with irreversible heart failure. It is also very important to ensure that an environment that facilitates the development, testing, and approval evaluation processes of next-generation artificial hearts be established as soon as possible.
Chopski, Steven G; Moskowitz, William B; Stevens, Randy M; Throckmorton, Amy L
The use of mechanical circulatory support (MCS) devices is a viable therapeutic treatment option for patients with congestive heart failure. Ventricular assist devices, cavopulmonary assist devices, and total artificial heart pumps continue to gain acceptance as viable treatment strategies for both adults and pediatric patients as bridge-to-transplant, bridge-to-recovery, and longer-term circulatory support alternatives. We present a review of the current and future MCS devices for patients having congenital heart disease (CHD) with biventricular or univentricular circulations. Several devices that are specifically designed for patients with complex CHD are in the development pipeline undergoing rigorous animal testing as readiness experiments in preparation for future clinical trials. These advances in the development of new blood pumps for patients with CHD will address a significant unmet clinical need, as well as generally improve innovation of the current state of the art in MCS technology. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Artificial organs have already become an important part of medical care, and with the advent of new devices, materials, and approaches, either in development or already on the market, they will become even more commonplace in the future.
Park, S S; Sanders, D B; Smith, B P; Ryan, J; Plasencia, J; Osborn, M B; Wellnitz, C M; Southard, R N; Pierce, C N; Arabia, F A; Lane, J; Frakes, D; Velez, D A; Pophal, S G; Nigro, J J
Mechanical circulatory support emerged for the pediatric population in the late 1980s as a bridge to cardiac transplantation. The Total Artificial Heart (TAH-t) (SynCardia Systems Inc., Tuscon, AZ) has been approved for compassionate use by the Food and Drug Administration for patients with end-stage biventricular heart failure as a bridge to heart transplantation since 1985 and has had FDA approval since 2004. However, of the 1,061 patients placed on the TAH-t, only 21 (2%) were under the age 18. SynCardia Systems, Inc. recommends a minimum patient body surface area (BSA) of 1.7 m(2), thus, limiting pediatric application of this device. This unique case report shares this pediatric institution's first experience with the TAH-t. A 14-year-old male was admitted with dilated cardiomyopathy and severe biventricular heart failure. The patient rapidly decompensated, requiring extracorporeal life support. An echocardiogram revealed severe biventricular dysfunction and diffuse clot formation in the left ventricle and outflow tract. The decision was made to transition to biventricular assist device. The biventricular failure and clot formation helped guide the team to the TAH-t, in spite of a BSA (1.5 m(2)) below the recommendation of 1.7 m(2). A computed tomography (CT) scan of the thorax, in conjunction with a novel three-dimensional (3D) modeling system and team, assisted in determining appropriate fit. Chest CT and 3D modeling following implantation were utilized to determine all major vascular structures were unobstructed and the bronchi were open. The virtual 3D model confirmed appropriate device fit with no evidence of compression to the left pulmonary veins. The postoperative course was complicated by a left lung opacification. The left lung anomalies proved to be atelectasis and improved with aggressive recruitment maneuvers. The patient was supported for 11 days prior to transplantation. Chest CT and 3D modeling were crucial in assessing whether the device would
Jones, R. T.
Certain hemodynamic phenomena that arise in connection with the use of artificial blood pumping devices are reviewed. Among these are: (1) Flows produced by collapsing bulbs; (2) the impedance presented by the aorta; (3) limiting velocities and instability of flow in elastic vessels; (4) effectiveness of valveless arterio-arterial pumps, and (5) wave reflection phenomena and instabilities associated with the intra-aortic balloon pump.
Harasaki, H; Fukamachi, K; Massiello, A; Chen, J F; Himley, S C; Fukumura, F; Muramoto, K; Niu, S; Wika, K; Davies, C R
A totally implantable, Cleveland Clinic-Nimbus total artificial heart (TAH) uses electrohydraulic energy conversion and an automatic left master-alternate mode control scheme, with a filling sensitivity of 1.0 l/min/mmHg and a maximum output of 9.5 l/min. The TAHs were tested in 12 calves for 1-120 days with normal major organ and blood cell function. Post-operative suppression of platelet aggregation recovered by the second post-operative week. The gelatin-coated pump surface generally was clean without any anticoagulants and free from infection. Embolism, which occurred in two cases, was caused by complications attributable to fungal infection in a Dacron graft and by thrombus formed around a jugular vein catheter. A system with a hybridized microcircuit controller in the interventricular space has been tested successfully in the three most recent cases, with a peak device surface temperature elevation of 6.5 degrees C. Heat effects were confined to the tissues immediately adjacent to the hottest spots. The carbon fiber-reinforced epoxy housing and 60 ml butyl rubber compliance chamber showed good tissue compatibility with a thin, fibrous tissue capsule. The transcutaneous energy transmission system and the internal battery functioned well as designed in the most recent animal implant.
Veatch, Robert M
It seems generally correct that patients (or their valid surrogates) should be able to withdraw consent for the use of the total artificial heart (TAH) just as they presently may withdraw consent for other life-prolonging technologies such as the ventilator, but lingering moral problems remain with such decisions. First, should patients be permitted to demand actual removal of the TAH rather than mere deactivation? Second, foregoing other life-prolonging technologies is normally considered "indirect" killing and is therefore judged legal (as well as moral to those who accept only indirect killing). As long as the society includes irreversible stoppage of the heart as one of the criteria for death, however, stopping a TAH will be considered direct killing, i.e., murder. To circumvent this inconsistency, society must change its conclusion that stopping other life-prolonging technologies is merely indirect killing, explicitly legalize direct killing by means of stopping a TAH, or revisit the definition of death to eliminate the cardiac standard for death from the definition of death. Assuming that the stopping of the TAH with patient or surrogate consent is acceptable, we must then face the question of whether physicians who believe the TAH is serving no purpose can unilaterally stop the device against the wishes of a patient or surrogate who believes it is still serving a worthwhile purpose. Clinicians should be presumed authoritative in determining the predicted effect of the TAH, but, if the TAH can temporarily prolong life for a patient in a way that is desired by the patient or surrogate, case law, professional society recommendation, and moral analysis all support the conclusion that the TAH must be continued even against the conscientious objection of the physician
... TAH is completely contained inside the chest. A battery powers this TAH. The battery is charged through the skin with a special ... Energy from the external charger reaches the internal battery through an energy transfer device called transcutaneous energy ...
Shah, Rachit; Patel, Dhavalkumar B; Mankad, Anit K; Rennyson, Stephen L; Tang, Daniel G; Quader, Mohammed A; Smallfield, Melissa C; Kasirajan, Vigneshwar; Shah, Keyur B
Pulmonary hypertension (PH) among heart transplant recipients is associated with an increased risk of mortality. Pulmonary hemodynamics improves after left ventricular assist device (LVAD) implantation; however, the impact of PH before total artificial heart (TAH) implantation on posttransplant hemodynamics and survival is unknown. This is a single center retrospective study aimed to evaluate the impact of TAH implantation on posttransplant hemodynamics and mortality in two groups stratified according to severity of PH: high (≥3 Woods units [WU]) and low (<3 WU) baseline pulmonary vascular resistance (PVR). Hemodynamic data were obtained from right heart catheterization performed at baseline (before TAH) and posttransplant at 1 and 12 months. Patients in the high PVR group (n = 12) experienced improvement in PVR (baseline = 4.31 ± 0.7; 1-month = 1.69 ± 0.7, p < 0.001; 12-month = 48 ± 0.9, p < 0.001) and transpulmonary gradient (baseline = 15.8 ± 3.3; 1-month = 11.57 ± 5.0, p = 0.07; 12-month = 8.50 ± 4.0, p = 0.008) after transplantation, reaching similar values as the low PVR group at 12 months. The filling pressures improved in the high PVR group after heart transplantation (HT), but remained elevated. There was no significant difference in survival between the two groups at 12 months follow-up. Patients with high PVR who are bridged to transplant with TAH had improvement in PVR at 12 months after transplant, and the degree of PVR did not impact posttransplant survival.
Federman, Myke; Dragomer, Douglas; Grant, Stuart; Reemtsen, Brian; Biniwale, Reshma
Heparin-induced thrombocytopenia presents a challenge for anticoagulation techniques during cardiac surgery and ventricular assist device implantation. Bivalirudin is currently recommended for use during cardiopulmonary bypass for patients with heparin-induced thrombocytopenia but requires the use of special techniques to avoid blood stagnation. We report the successful use of bivalirudin during cardiopulmonary bypass for implantation of the Total Artificial Heart with late operative bleeding likely resulting from heavy cell saver use.
Pugliesi, R.; Geraldo, L. P.; Andrade, M. L. G.; Menezes, M. O.,; Pereira, M. A. S.; Maizato, M. J. S.
The neutron radiography technique was employed to inspect an artificial heart prototype which is being developed to provide blood circulation for patients expecting heart transplant surgery. The radiographs have been obtained by the direct method with a gadolinium converter screen along with the double coated Kodak-AA emulsion film. The artificial heart consists of a flexible plastic membrane located inside a welded metallic cavity, which is employed for blood pumping purposes. The main objective of the present inspection was to identify possible damages in this plastic membrane, produced during the welding process of the metallic cavity. The obtained radiographs were digitized as well as analysed in a PC and the improved images clearly identify several damages in the plastic membrane, suggesting changes in the welding process.
Barac, Ileana Ramona; Pop, Monica
Glaucoma is a degenerative optic neuropathy progressive, multifactorial, which can lead to blindness. Blindness in patients with glaucoma is defined as visual field reduction below 10 degrees. Artificial drainage systems are a solution for refractory to medication, laser treatment or conventional surgery. Used by over 100 years, improved with good surgical technique and careful patient follow-up surgery, postoperative results are satisfactory.
Piegat, Agnieszka; Fray, Mirosława El
Heart assisting devices have become a standard element in clinical practice and provide support for the traditional methods of treating heart disease. Regardless of the construction of VAD (ventricular assist devices), there are crucial requirements that have to be met by the construction materials: high purity, desired physical, chemical and mechanical properties, easy fabrication and high stability and susceptibility to sterilization. They must not cause thrombosis, destroy cellular elements, alter plasma protein, destroy enzymes, deplete electrolytes, cause immune response and cancer, and must not produce toxic and allergic reactions, when they are applied in direct contact with biological tissues and fluids. This paper provides an overview of the polymeric materials as construction materials for cardiovascular support systems, focusing on the group of thermoplastic elastomers, mainly polyurethane and polyester based ones. It also highlights the advantages and disadvantages of currently used materials and the progress in the design of new materials with potential application in the biomedical field.
Sturm, J. T.; Bossart, M. I.; Holub, D. A.; Milam, J. D.; Norman, J. C.
Ischemic myocardial contracture developed in a 21-year-old man following aortic and mitral valve replacement. The patient's circulation was supported totally for 6 days with an abdominal left ventricular assist device (ALVAD). Cardiac allografting was then undertaken. Samples of myocardium taken at the original operation and 6 days later at transplantation were analyzed ultrastructurally. At the onset of ischemic cortracture, left ventricular abnormalities included hypercontraction of myofibrils, loss of normal A-band and Z-band patterns, mitochondrial swelling with fusion of cristae, interfibrillar edema and glycogen depletion. Capillaries demonstrated swelling of endothelial cells and basement membrane disruption. Six days later, ultrastructural morphology showed further degeneration. The myofibrils remained hypercontracted, but were more fragmented. Degenerative changes in mitochondria were more advanced and calcium deposition in cristae was present. No glycogen was seen. The right ventricular myocardium exhibited significantly fewer ultrastructural abnormalities. The principal right ventricular changes were endothelial swelling and basement membrane disruption. Glycogen granules were present. Ischemic contracture affects the left ventricle more than the right, and the morphology becomes more abnormal with time. To our knowledge, this is the first instance wherein morphologic progressions of the ultrastructural alterations of ischemic contracture have been documented. Images PMID:15216023
Parker, Mark S; Fahrner, Lester J; Deuell, Brian P F; Olsen, Kathryn M; Kasirajan, Vigneshwar; Shah, Keyur B; Medina, Angel E; Doolin, Kelly R; de Groot, Patricia M; de Groot, Patti Ann; Goodman, William C
The purposes of this article are to review the treatment options for late-stage biventricular heart failure, discuss the clinical indications for total artificial heart (TAH) implantation, illustrate the expected imaging findings after uncomplicated TAH implantation, and highlight the radiologic findings of common and uncommon complications associated with TAH implantation through case examples. TAH implantation is an effective therapeutic option for the treatment of patients with end-stage biventricular heart failure. The duration of implantation varies depending on a particular patient's medical condition and the eventual availability of a human heart for orthotopic transplantation. TAH recipients often undergo imaging with conventional radiography, CT, or both for the assessment of device-related issues, many of which are life-threatening and require emergency management. As the clinical use of the TAH increases and becomes more commonplace, it is imperative that radiologists interpreting imaging studies recognize both the expected and the unexpected imaging findings that affect patient care.
Andrade, Aron; Fonseca, Jeison; Legendre, Daniel; Nicolosi, Denys; Biscegli, Jose; Pinotti, Marcos; Ohashi, Yukio; Nosé, Yukihiko
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 degrees 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.
Tozzi, Piergiorgio; Maertens, Audrey; Emery, Jonathan; Joseph, Samuel; Kirsch, Matthias; Avellan, François
We present the test bench results of a valveless total artificial heart that is potentially compatible with the pediatric population. The RollingHeart is a valveless volumetric pump generating pulsatile flow. It consists of a single spherical cavity divided into 4 chambers by 2 rotating disks. The combined rotations of both disks produce changes in the volumes of the 4 cavities (suction and ejection). The blood enters/exits the spherical cavity through 4 openings that are symmetrical to the fixed rotation axis of the first disk.Mock circulatory system: The device pumps a 37% glycerin solution through 2 parallel circuits, simulating the pulmonary and systemic circulations. Flow rates are acquired with a magnetic inductive flowmeter, while pressure sensors collect pressure in the left and right outflow and inflow tracts.In vitro test protocol: The pump is run at speeds ranging from 20 to 180 ejections per minute. The waveform of the pressure generated at the inflow and outflow of the 4 chambers and the flow rate in the systemic circulation are measured. At an ejection rate of 178 min-1, the RollingHeart pumps 5.3 L/min for a systemic maximal pressure gradient of 174 mmHg and a pulmonary maximal pressure gradient of 75 mmHg. The power input was 14 W, corresponding to an efficiency of 21%. The RollingHeart represents a new approach in the domain of total artificial heart. This preliminary study endorses the feasibility of a single valveless device acting as a total artificial heart.
Bruckner, Brian A; Abu Saleh, Walid K; Al Jabbari, Odeaa; Copeland, Jack G; Estep, Jerry D; Loebe, Matthias; Reardon, Michael J
Primary cardiac sarcomas, although rare, are aggressive and lethal, requiring thorough surgical resection and adjuvant chemotherapy for the best possible outcome. We report the case of a 32-year-old woman who underwent total artificial heart implantation for right-sided heart failure caused by right ventricular angiosarcoma. For the first several weeks in intensive care, the patient recovered uneventfully. However, a postoperative liver biopsy indicated hepatocellular injury consistent with preoperative chemotherapy. She developed continuing liver failure, from which she died despite good cardiac function.
Arusoglu, Latif; Reiss, Nils; Morshuis, Michiel; Schoenbrodt, Michael; Hakim-Meibodi, Kavous; Gummert, Jan
The CardioWest™ total artificial heart (SynCardia Systems, Tuscon, AZ, USA) is the only FDA-approved total artificial heart determined as a bridge to human heart transplantation for patients dying of biventricular heart failure. Implantation provides immediate hemodynamic restoration and clinical stabilization, leading to end-organ recovery and thus eventually allowing cardiac transplantation. Occasionally, implantation of a total artificial heart is not feasible for anatomical reasons. For this patient group, we have developed an alternative technique using the paracorporeal Thoratec biventricular support system (Thoratec, Pleasanton, CA, USA) as a modified total artificial heart. A detailed description of the implantation technique is presented.
Sonntag, Simon J; Kaufmann, Tim A S; Büsen, Martin R; Laumen, Marco; Gräf, Felix; Linde, Torsten; Steinseifer, Ulrich
For blood pumps with long term indication, blood stagnation can result in excessive thromboembolic risks for patients. This study numerically investigates the washout performance of the left pump chamber of a pulsatile total artificial heart (TAH) as well as the sensitivity of the rotational orientation of the inlet bileaflet mechanical heart valve (MHV) on blood stagnation. To quantitatively evaluate the washout efficiency, a fluid-structure interaction (FSI) simulation of the artificial heart pumping process was combined with a blood washout model. Four geometries with different orientations (0°, 45°, 90° and 135°) of the inlet valve were compared with respect to washout performance. The calculated flow field showed a high level of agreement with particle image velocimetry (PIV) measurements. Almost complete washout was achievable after three ejection phases. Remains of old blood in relation to the chamber volume was below 0.6% for all configurations and were mainly detected opposite to the inlet and outlet port at the square edge where the membrane and the pump chamber are connected. Only a small variation in the washout efficiency and the general flow field was observed. An orientation of 0° showed minor advantages with respect to blood stagnation and recirculation. Bileaflet MHVs were demonstrated to be only slightly sensitive to rotation regarding the washout performance of the TAH. The proposed numerical washout model proved to be an adequate tool to quantitatively compare different configurations and designs of the artificial organ regarding the potential for blood stagnation where experimental measurements are limited.
Rogers, Stuart E.; Kutler, Paul; Kwak, Dochan; Kiris, Cetin
A solution procedure was developed that solves the unsteady, incompressible Navier-Stokes equations, and was used to numerically simulate viscous incompressible flow through a model of the Pennsylvania State artificial heart. The solution algorithm is based on the artificial compressibility method, and uses flux-difference splitting to upwind the convective terms; a line-relaxation scheme is used to solve the equations. The time-accuracy of the method is obtained by iteratively solving the equations at each physical time step. The artificial heart geometry involves a piston-type action with a moving solid wall. A single H-grid is fit inside the heart chamber. The grid is continuously compressed and expanded with a constant number of grid points to accommodate the moving piston. The computational domain ends at the valve openings where nonreflective boundary conditions based on the method of characteristics are applied. Although a number of simplifing assumptions were made regarding the geometry, the computational results agreed reasonably well with an experimental picture. The computer time requirements for this flow simulation, however, are quite extensive. Computational study of this type of geometry would benefit greatly from improvements in computer hardware speed and algorithm efficiency enhancements.
Abe, Yusuke; Isoyama, Takashi; Saito, Itsuro; Inoue, Yusuke; Ishii, Kohei; Sato, Masami; Hara, Shintaro; Yurimoto, Terumi; Li, Xinyang; Murakami, Haruka; Ariyoshi, Koki; Kawase, Yukino; Ono, Toshiya; Fukazawa, Kyoko; Ishihara, Kazuhiko
Severe cardiac failure patients require a total artificial heart (TAH) to save life. To realize a TAH that can fit a body of small stature and has high performance, high durability, good anatomical fitting, good blood compatibility, and physiological control, we have been developing the helical flow TAH (HFTAH) with two helical flow pumps with hydrodynamic levitation impeller. Animal experiments of the HFTAH were conducted to perform in vivo studies. The HFTAH was implanted in 13 adult female goats weighing 45.0-64.0 kg. After surgery, neither anti-coagulant nor anti-platelet medication was given systemically. The HFTAH was usually driven with a quasi-pulsatile mode. The 1/R control or ΔP control was applied to control the circulation. The ΔP control is a new method using simplified equation of the 1/R control. The HFTAH could be implanted in all goats with good anatomical fitting. Two goats survived for a long time (100 and 68 days). Major causes of termination were device failure and surgical complications. In the device failure, trouble with hydrodynamic bearing was conspicuous. In the two long-term survived goats, experiments were terminated with bearing instability that was probably caused by the suction effect. In these goats, hemolysis occurred on postoperative day 88 and 44, which was considered to be relevant to the bearing trouble. Thrombus was found at the broken right bearing of the 100-day survived goat. However, antithrombogenicity of the pump is expected to be good unless bearing trouble occurs. In two long-term survived goats, the 1/R control or ΔP control worked appropriately to prevent the elevation of right atrial pressure. In both goats, hemodynamic parameters changed with the condition of the animals, liver and kidney functions remained almost normal except when recovering from surgery and during hemolysis, and total protein recovered 2 weeks after surgery. Although instability of the hydrodynamic bearing should be improved, performance of
Marom, Gil; Chiu, Wei-Che; Slepian, Marvin J; Bluestein, Danny
The total artificial heart (TAH) is a bi-ventricular mechanical circulatory support device that replaces the heart in patients with end-stage congestive heart failure. The device acts as blood pump via pneumatic activation of diaphragms altering the volume of the ventricular chambers. Flow in and out of the ventricles is controlled by mechanical heart valves. The aim of this study is to evaluate the flow regime in the TAH and to estimate the thrombogenic potential during systole. Toward that goal, three numerical models of TAHs of differing sizes, that include the deforming diaphragm and the blood flow from the left chamber to the aorta, are introduced. A multiphase model with injection of platelet particles is employed to calculate their trajectories. The shear stress accumulation in the three models are calculated along the platelets trajectories and their probability density functions, which represent the `thrombogenic footprint' of the device are compared. The calculated flow regime successfully captures the mitral regurgitation and the flows that open and close the aortic valve during systole. Physiological velocity magnitudes are found in all three models, with higher velocities and increased stress accumulation predicted for smaller devices.
Massiello, A; Kiraly, R; Butler, K; Himley, S; Chen, J F; McCarthy, P M
We describe the design and in vitro testing of the Cleveland Clinic-Nimbus electrohydraulic permanent total artificial heart as it nears completion of development. The total artificial heart uses an electric motor and hydraulic actuator to drive two diaphragm-type blood pumps. The interventricular space contains the pump control electronics and is vented to an air-filled compliance chamber. Pericardial tissue valves and biolized blood-contacting surfaces potentially eliminate the need for anticoagulation. In vitro studies on a mock circulatory circuit demonstrated preload-sensitive control of pump output over the operating range of the blood pump: 70 to 160 beats/min and 5 to 9.6 L/min at right and left atrial pressures of 1.0 to 7.0 mm Hg and 5.0 to 12.0 mm Hg, respectively. The pump output was found to be insensitive to afterload over a range of 15 to 40 mm Hg mean pulmonary artery pressure and 60 to 130 mm Hg mean systemic pressure. The left master alternate control mode balanced the ventricular outputs during simulated bronchial artery shunting of up to 20% of cardiac output. A 10% to 15% right-pump, stroke-volume limiter balanced ventricular outputs during maximum output of 9.6 L/min. In response to a sustained increase in systemic venous return, the pump increased output by 2 L/min (29%) in 35 seconds. Thus the Cleveland Clinic-Nimbus total artificial heart meets the National Heart, Lung, and Blood Institute hemodynamic performance goals for devices being developed for permanent heart replacement. The biolized blood-contacting surfaces should decrease the risk of thromboembolism associated with circulatory assist devices.
Petri, Aspasia; Karabetsos, Efthymios
Artificial tanning remains very popular worldwide, despite the International Agency for Research on Cancer classification of ultraviolet (UV) radiation from sunbeds as 'carcinogenic to humans'. Greek Atomic Energy Commission has initiated a surveillance action of the artificial tanning devices in Greece in order to record the effective irradiance levels from the sunbeds and to inform and synchronise the domestic artificial tanning business sector with the requirements of the European Standard EN 60335-2-27:2010. In this direction, in situ measurements of UV emissions from sunbeds in solaria businesses all over Greece were performed from October 2013 until July 2014, with a radiometer and a portable single-monochromator spectrophotometer. Analysis of the measurements' results revealed that effective irradiance in ∼60 % of the measured sunbeds exceeded the 0.3 W m(-2) limit value set by EN 60335-2-27:2010 and only 20 % of the devices could be categorised as UV type 3.
Mehta, S M; Aufiero, T X; Pae, W E; Miller, C A; Pierce, W S
The Combined Registry has existed since 1985 with a design toward the voluntary submission of data from centers undertaking mechanical circulatory assistance. The compiled results of the Combined Registry for the Clinical Use of Mechanical Ventricular Assist Pumps and the Total Artificial Heart was reviewed and subjected to strict statistical evaluation. More than 2000 implanted devices have been reported through January 1994, and 584 of these have been placed with the intention of bridge to heart transplantation. Nearly 70% of these patients have subsequently undergone heart transplantation, and 69% of those patients have survived to discharge from the hospital. Outcome statistics continue to favor isolated left ventricular support, although only discharge rates are significantly improved over right (p = 0.01) or biventricular assistance (p < 0.001) and the total artificial heart (p < 0.001). Within the group of left ventricular devices no individual mode of support proved advantageous over the others for transplantation or discharge rates. The 30-day mortality for all devices is approximately 36%, which remains much higher than that for orthotopic heart transplants. Isolated left ventricular support, however, had a 30-day mortality of only 9% with similar improvement in 12- and 24-month survival. These data show the continued success with these devices for bridging critically ill patients to transplantation. Additionally, it supports the ongoing development of devices implanted for long-term use, which might replace orthotopic transplantation for those patients currently deemed marginal candidates.
... More Shock from heart device often triggers further health care needs American Heart Association Rapid Access Journal Report ... cardioverter defibrillator (ICD) may trigger an increase in health care needs for many patients, regardless whether the shock ...
Pelletier, Benedikt; Spiliopoulos, Sotirios; Finocchiaro, Thomas; Graef, Felix; Kuipers, Kristin; Laumen, Marco; Guersoy, Dilek; Steinseifer, Ulrich; Koerfer, Reiner; Tenderich, Gero
Owing to the lack of suitable allografts, the demand for long-term mechanical circulatory support in patients with biventricular end-stage heart failure is rising. Currently available Total Artificial Heart (TAH) systems consist of pump units with only limited durability, percutaneous tubes and bulky external equipment that limit the quality of life. Therefore we are focusing on the development of a fully implantable, highly durable destination therapy total artificial heart. The ReinHeart-TAH system consists of a passively filling pump unit driven by a low-wear linear drive between two artificial ventricles, an implantable control unit and a compliance chamber. The TAH is powered by a transcutaneous energy transmission system. The flow distribution inside the ventricles was analysed by fluid structure interaction simulation and particle image velocimetry measurements. Along with durability tests, the hydrodynamic performance and flow balance capability were evaluated in a mock circulation loop. Animal trials are ongoing. Based on fluid structure interaction simulation and particle image velocimetry, blood stagnation areas have been significantly reduced. In the mock circulation loop the ReinHeart-TAH generated a cardiac output of 5 l/min at an operating frequency of 120 bpm and an aortic pressure of 120/80 mmHg. The highly effective preload sensitivity of the passively filling ventricles allowed the sensorless integration of the Frank Starling mechanism. The ReinHeart-TAH effectively replaced the native heart's function in animals for up to 2 days. In vitro and in vivo testing showed a safe and effective function of the ReinHeart-TAH system. This has the potential to become an alternative to transplantation. However, before a first-in-man implant, chronic animal trials still have to be completed. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
Quader, Mohammed A; Goodreau, Adam M; Shah, Keyur B; Katlaps, Gundars; Cooke, Richard; Smallfield, Melissa C; Tchoukina, Inna F; Wolfe, Luke G; Kasirajan, Vigneshwar
Heart failure patients requiring total artificial heart (TAH) support often have concomitant renal insufficiency (RI). We sought to quantify renal function recovery in patients supported with TAH at our institution. Renal function data at 30, 90, and 180 days after TAH implantation were analyzed for patients with RI, defined as hemodialysis supported or an estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 m. Between January 2008 and December 2013, 20 of the 46 (43.5%) TAH recipients (age 51 ± 9 years, 85% men) had RI, mean preoperative eGFR of 48 ± 7 ml/min/1.73 m. Renal function recovery was noted at each follow-up interval: increment in eGFR (ml/min/1.73 m) at 30, 90, and 180 days was 21 ± 35 (p = 0.1), 16.5 ± 18 (p = 0.05), and 10 ± 9 (p = 0.1), respectively. Six patients (30%) required preoperative dialysis. Of these, four recovered renal function, one remained on dialysis, and one died. Six patients (30%) required new-onset dialysis. Of these, three recovered renal function and three died. Overall, 75% (15 of 20) of patients' renal function improved with TAH support. Total artificial heart support improved renal function in 75% of patients with pre-existing significant RI, including those who required preoperative dialysis.
Pokrovskiĭ, V M; Abushkevich, V G; Dashkovskiĭ, A I; Shapiro, S V; Diak, I A
High-frequency artificial hyperventilation of cat lung with a rate above the initial rhythm of the heart reconstructs the rhythm so that each breathing cycle coincides with one systole of the heart. Synchronization of breathing movements and heart systoles is easily removed by atropine, and cold blockade of vagus nerves by open artificial pneumothorax.
Biological neural networks perform complicated information processing tasks at speeds better than conventional computers based on conventional algorithms. This has inspired researchers to look into the way these networks function, and propose artificial networks that mimic their behavior. Unfortunately, most artificial neural networks, either software or hardware, do not provide either the speed or the complexity of a human brain. Nanoelectronics, with high density and low power dissipation that it provides, may be used in developing more efficient artificial neural networks. This work consists of two major contributions in this direction. First is the proposal of the CMOL concept, hybrid CMOS-molecular hardware [1-8]. CMOL may circumvent most of the problems in posed by molecular devices, such as low yield, vet provide high active device density, ˜1012/cm 2. The second contribution is CrossNets, artificial neural networks that are based on CMOL. We showed that CrossNets, with their fault tolerance, exceptional speed (˜ 4 to 6 orders of magnitude faster than biological neural networks) can perform any task any artificial neural network can perform. Moreover, there is a hope that if their integration scale is increased to that of human cerebral cortex (˜ 1010 neurons and ˜ 1014 synapses), they may be capable of performing more advanced tasks.
Shumakov, V I; Itkin, G P; Sumin, A V; Mordashov, V M; Kiselev, U M; Zimin, N K; Drobyshev, A A
The totally artificial heart (TAH) is now in development in two trends. First, there is the development of a bridge system for temporary support of cardiac function. The TAH with the extracorporeal pneumatic driving system Sinus-IS is more efficient and safer. Parallel with this, a portable pneumatic driving system has been developed. That can be considered a stage in the development of the second trend: a totally implantable TAH. This article reviews problems of building of the Micron energy system to be used in implantable TAH designs.
Karimov, Jamshid H; Horvath, David; Sunagawa, Gengo; Byram, Nicole; Moazami, Nader; Golding, Leonard A R; Fukamachi, Kiyotaka
Post-explant evaluation of the continuous-flow total artificial heart in preclinical studies can be extremely challenging because of the device's unique architecture. Determining the exact location of tissue regeneration, neointima formation, and thrombus is particularly important. In this report, we describe our first successful experience with visualizing the Cleveland Clinic continuous-flow total artificial heart using a custom-made high-definition miniature camera.
Potnuru, Akshay; Tadesse, Yonas
Previously, we have presented the design and characterization of artificial heart using cylindrical shape memory alloy (SMA) actuators for humanoids . The robotic heart was primarily designed to pump a blood-like fluid to parts of the robot such as the face to simulate blushing or anger by the use of elastomeric substrates for the transport of fluids. It can also be used for other applications. In this paper, we present an improved design by using high strain coiled SMAs and a novel pumping mechanism that uses sequential actuation to create peristalsis-like motions, and hence pump the fluid. Various placements of actuators will be investigated with respect to the silicone elastomeric body. This new approach provides a better performance in terms of the fluid volume pumped.
Ji, Jinghua; Wang, Fangqun; Bian, Fangfang
This paper proposes a new electromechanical energy conversion system, called Field Modulated Magnetic Screw (FMMS) as a high force density linear actuator for artificial heart. This device is based on the concept of magnetic screw and linear magnetic gear. The proposed FMMS consists of three parts with the outer and inner carrying the radially magnetized helically permanent-magnet (PM), and the intermediate having a set of helically ferromagnetic pole pieces, which modulate the magnetic fields produced by the PMs. The configuration of the newly designed FMMS is presented and its electromagnetic performances are analyzed by using the finite-element analysis, verifying the advantages of the proposed structure. PMID:28217410
Tuzun, Egemen; Parnis, Steve; Rios, Jesse; Winkler, Jo Anna; Cohn, William E.
Although current continuous-flow total artificial hearts (CFTAHs) are much smaller than previous models, venous kinking may still occur after device implantation, especially in smaller animals. By inserting a self-expanding stent at the site of venous narrowing in a sheep model implanted with a CFTAH, we were able to restore the normal venous geometry and dramatically increase the CFTAH output. Because this percutaneous approach avoids the challenges associated with reoperation in these cases, it may be useful to other CFTAH investigators. PMID:21615430
Ling, Zhijian; Ji, Jinghua; Wang, Fangqun; Bian, Fangfang
This paper proposes a new electromechanical energy conversion system, called Field Modulated Magnetic Screw (FMMS) as a high force density linear actuator for artificial heart. This device is based on the concept of magnetic screw and linear magnetic gear. The proposed FMMS consists of three parts with the outer and inner carrying the radially magnetized helically permanent-magnet (PM), and the intermediate having a set of helically ferromagnetic pole pieces, which modulate the magnetic fields produced by the PMs. The configuration of the newly designed FMMS is presented and its electromagnetic performances are analyzed by using the finite-element analysis, verifying the advantages of the proposed structure.
Ling, Zhijian; Ji, Jinghua; Wang, Fangqun; Bian, Fangfang
This paper proposes a new electromechanical energy conversion system, called Field Modulated Magnetic Screw (FMMS) as a high force density linear actuator for artificial heart. This device is based on the concept of magnetic screw and linear magnetic gear. The proposed FMMS consists of three parts with the outer and inner carrying the radially magnetized helically permanent-magnet (PM), and the intermediate having a set of helically ferromagnetic pole pieces, which modulate the magnetic fields produced by the PMs. The configuration of the newly designed FMMS is presented and its electromagnetic performances are analyzed by using the finite-element analysis, verifying the advantages of the proposed structure.
Hayward, Robert M; Dewland, Thomas A; Moyers, Brian; Vittinghoff, Eric; Tanel, Ronn E; Marcus, Gregory M; Tseng, Zian H
Pacemakers and implantable cardioverter-defibrillators (ICDs) are increasingly implanted in adults with congenital heart disease (CHD), but little is known about implant-related complications and mortality. The purpose of this study was to compare pacemaker and ICD implantation complication rates between adults with and those without CHD using a comprehensive, statewide database. We used the Healthcare Cost and Utilization Project database to identify initial transvenous pacemaker and ICD implantations and implant-related complications in California hospitals from January 1, 2005, to December 31, 2011. We calculated relative risks of implant-related complications by comparing those with and those without CHD using Poisson regression with robust standard errors, adjusting for age and medical comorbidities. We identified 105,852 patients undergoing pacemaker implantation, 1465 with noncomplex CHD and 66 with complex CHD. CHD was not associated with increased risk of pacemaker implant-related complications: adjusted risk ratio (aRR) 0.92, 95% confidence interval (CI) 0.74-1.14, P = .45. We identified 32,948 patients undergoing ICD implantation, 815 with noncomplex CHD and 87 with complex CHD. Patients with CHD had increased risk of ICD implant-related complications: aRR 1.36, 95% CI 1.05-1.76, P = .02. Patients with complex CHD had greater increased risk of ICD implant-related complications: aRR 2.14, 95% CI 1.16-3.95, P = .02. In patients receiving devices, CHD was associated with a trend toward lower 30-day in-hospital mortality after pacemaker (P = .07) and ICD (P = .19) implantation. Among adult patients undergoing device implantation in California, CHD was associated with increased risk of ICD implant-related complications, but not pacemaker implant-related complications or higher 30-day in-hospital mortality. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
... said, is that it could overheat the device wires, possibly injuring the heart muscle or altering how ... had a "failure" in their device or its wires during the MRI. And none suffered a dangerous ...
Ryan, Thomas D; Jefferies, John L; Zafar, Farhan; Lorts, Angela; Morales, David L S
Advances in medical therapies have yielded improvement in morbidity and a decrease in mortality for patients with congenital heart disease, both surgically palliated and uncorrected. An unintended consequence is a cohort of adolescent and adult patients with heart failure who require alternative therapies. One intriguing option is placement of a total artificial heart (TAH) either as a bridge to transplant or as a destination therapy. Of the 1091 Jarvik-7 type TAH (Symbion, CardioWest and SynCardia) placed between 1985 and 2012, only 24 have been performed in patients with congenital heart disease, and a total of 51 were placed in patients younger than 21. At our institution, the SynCardia TAH was implanted in a 19-year-old patient with cardiac allograft failure because of chronic rejection and related multisystem organ failure including need for hemodialysis. Over the next year, she was nutritionally and physically rehabilitated, as were her end organs, allowing her to come off dialysis, achieve normal renal function and eventually be successfully transplanted. Given the continued growth of adolescent and adult congenital heart disease populations with end-stage heart failure, the TAH may offer therapeutic options where previously there were few. In addition, smaller devices such as the SynCardia 50/50 will open the door for applications in smaller children. The Freedom Driver offers the chance for patients to leave the hospital with a TAH, as does the AbioCor, which is a fully implantable TAH option. In this report, we review the history of the TAH and potential applications in adolescent patients and congenital heart disease.
Copeland, Jack; Copeland, Hannah; Nolan, Paul; Gustafson, Monica; Slepian, Marvin; Smith, Richard
For 15 years, we employed a consistent anticoagulation protocol in 99 consecutive SynCardia Systems total artificial heart (TAH) recipients. Thromboelastography and platelet aggregation studies were used for evaluating and modulating therapy with dipyridamole, pentoxiphylline, aspirin, and heparin. Partial thromboplastin times, international normalized ratios, and platelet counts were also followed. After the second post-implant day in patients who were free of endo-device infection (97 patients), the embolic stroke incidence was 0.08 per patient year. This included 23.6 patient years of device support. There were no spontaneous hemorrhagic strokes. Two patients had endo-device infections and both had strokes. Postimplantation bleeding was seen in 20% of patients. All but two of these were within the first postoperative week. In all, 4% of patients had gastrointestinal bleeding. We did not observe heparin-induced thrombocytopenia in any patient. We conclude that stroke rates on TAH support have been low, and recommend this protocol.
Karimov, Jamshid H; Sunagawa, Gengo; Golding, Leonard A R; Moazami, Nader; Fukamachi, Kiyotaka
In vivo preclinical testing of mechanical circulatory devices requires large animal models that provide reliable physiological and hemodynamic conditions by which to test the device and investigate design and development strategies. Large bovine species are commonly used for mechanical circulatory support device research. The animals used for chronic in vivo support require high-quality care and excellent surgical techniques as well as advanced methods of postoperative care. These techniques are constantly being updated and new methods are emerging.We report results of our double steel-wire closure technique in large bovine models used for Cleveland Clinic's continuous-flow total artificial heart development program. This is the first report of double-wire sternal fixation used in large bovine models.
Zaheer, Aneel; West, Justin Mark; Danton, Mark H D
Percutaneous cardiovascular device implantation plays an important and increasing role in the treatment of congenital heart disease. Device related complications of malposition and embolisation are uncommon and can usually be retrieved by catheter. We present two interesting cases in which migrated devices resulted in thoracic aortic obstruction; both were refractory to percutaneous retrieval. Device retrieval was achieved by thoracotomy and utilising partial left heart bypass because of specific concerns of distal perfusion. Our experience is presented.
Carpentier, Alain; Latrémouille, Christian; Cholley, Bernard; Smadja, David M; Roussel, Jean-Christian; Boissier, Elodie; Trochu, Jean-Noël; Gueffet, Jean-Pierre; Treillot, Michèle; Bizouarn, Philippe; Méléard, Denis; Boughenou, Marie-Fazia; Ponzio, Olivier; Grimmé, Marc; Capel, Antoine; Jansen, Piet; Hagège, Albert; Desnos, Michel; Fabiani, Jean-Noël; Duveau, Daniel
The development of artificial hearts in patients with end-stage heart disease have been confronted with the major issues of thromboembolism or haemorrhage. Since valvular bioprostheses are associated with a low incidence of these complications, we decided to use bioprosthetic materials in the construction of a novel artificial heart (C-TAH). We report here the device characteristics and its first clinical applications in two patients with end-stage dilated cardiomyopathy. The aim of the study was to evaluate safety and feasibility of the CARMAT TAH for patients at imminent risk of death from biventricular heart failure and not eligible for transplant. The C-TAH is an implantable electro-hydraulically actuated pulsatile biventricular pump. All components, batteries excepted, are embodied in a single device positioned in the pericardial sac after excision of the native ventricles. We selected patients admitted to hospital who were at imminent risk of death, having irreversible biventricular failure, and not eligible for heart transplantation, from three cardiac surgery centres in France. The C-TAH was implanted in two male patients. Patient 1, aged 76 years, had the C-TAH implantation on Dec 18, 2013; patient 2, aged 68 years, had the implantation on Aug 5, 2014. The cardiopulmonary bypass times for C-TAH implantation were 170 min for patient 1 and 157 min for patient 2. Both patients were extubated within the first 12 postoperative hours and had a rapid recovery of their respiratory and circulatory functions as well as a normal mental status. Patient 1 presented with a tamponade on day 23 requiring re-intervention. Postoperative bleeding disorders prompted anticoagulant discontinuation. The C-TAH functioned well with a cardiac output of 4·8-5·8 L/min. On day 74, the patient died due to a device failure. Autopsy did not detect any relevant thrombus formation within the bioprosthesis nor the different organs, despite a 50-day anticoagulant-free period. Patient 2
Smit, Francis E; Dohmen, Pascal M
End-stage heart failure is a major health problem, but implementation of guidelines and optimizing medical therapy for this devastating disease should decrease mortality. If optimal conservative therapy is no longer sufficient, a mechanical support system may be required as final destination therapy or as bridge-to-transplant. Since the first heart transplantation in 1967, this therapy has become the criterion standard for end-stage heart failure, but is limited due to organ shortage. Tissue engineering could help overcome this limitation and provide regeneration, remodeling, and growth potential. This so-called bio-artificial heart would be available, created by a decellularized extracellular matrix and seeded with in vitro proliferated autologous cardiovascular cells. Results of the first experimental studies have been promising, but numerous challenges must be met before this procedure will be available.
Nestler, Frank; Bradley, Andrew P; Wilson, Stephen J; Timms, Daniel L; Frazier, O Howard; Cohn, William E
Rotary blood pumps are emerging as a viable technology for total artificial hearts, and the development of physiological control algorithms is accelerated with new evaluation environments. In this article, we present a novel hybrid mock circulation loop (HMCL) designed specifically for evaluation of rotary total artificial hearts (rTAH). The rTAH is operated in the physical domain while all vasculature elements are embedded in the numerical domain, thus combining the strengths of both approaches: fast and easy exchange of the vasculature model together with improved controllability of the pump. Parameters, such as vascular resistance, compliance, and blood volume, can be varied dynamically in silico during operation. A hydraulic-numeric interface creates a real-time feedback loop between the physical and numerical domains. The HMCL uses computer-controlled resistance valves as actuators, thereby reducing the size and number of hydraulic elements. Experimental results demonstrate a stable interaction over a wide operational range and a high degree of flexibility. Therefore, we demonstrate that the newly created design environment can play an integral part in the hydraulic design, control development, and durability testing of rTAHs.
Hansen, Adam J; Copeland, Jack G
Combined, single-donor, heart and kidney transplant (HKTx) recipients have survival rates comparable with those after heart transplantation alone. Although HKTx provides superior outcomes in patients with dual-organ failure, appropriate single-donor organ pairs are very scarce. Mechanical circulatory support thus seems an attractive option as a bridge to HKTx. We report the case of an adult with end-stage cardiomyopathy and renal failure who was successfully bridged to combined, single-donor HKTx with a total artificial heart. Infectious complications associated with the CardioWest cavity were encountered prior to transplantation. The patient recovered and was discharged 14 days after transplantation. At 4 months post-transplantation, the patient required single-vessel coronary stenting for a high-grade stenosis. At 1 year, he has had no further complications and has excellent function of both transplanted organs. Despite limited availability of same donor organ pairs, patients with combined cardiac and renal failure can be bridged effectively to transplant with the CardioWest total artificial heart. Copyright © 2010 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.
Li, Xiuping; Gao, Jianjun; Boeck, Georg
An approach for the microwave nonlinear device modelling technique based on a combination of the conventional equivalent circuit model and artificial neural network (ANN) is presented in this paper. The main advantage of the proposed method is that the integration and differential of an ANN can directly be carried out from the original ANN. The proposed technique is very useful for neural-based microwave computer-aided design, and for analytically unified dc, small signal and nonlinear device modelling. Examples of the Schottky diode and PHEMT linear/nonlinear modelling utilizing the proposed integration and differential technique are demonstrated.
McCarthy, P M; Fukamachi, K; Fukumura, F; Muramoto, K; Golding, L A; Harasaki, H
In vitro function of the Cleveland Clinic-Nimbus electrohydraulic total artificial heart met National Heart, Lung, and Blood Institute hemodynamic guidelines for such devices. In a series of in vivo experiments, we implanted the total artificial heart in eight calves (mean weight 87 kg), one for a short-term experiment and seven for long-term experiments. The mean blood flow during support was 7.7 +/- 1.6 L/min with left atrial pressure 13 +/- 6 mm Hg, right atrial pressure 13 +/- 4 mm Hg, and aortic pressure 97 +/- 9 mm hg. Maximum pump flow (9.6 L/min) occurred after 4 days of support as a result of the high resting cardiac output of the animals. A 10% to 15% right pump stroke-volume limit effectively balanced atrial pressures, and afterload insensitivity was confirmed by the in vivo studies. Calves tolerated treadmill exercise studies well, with an average duration of 22 minutes and an average top speed of 2.1 mph. The experiments were terminated after 1 day to 120 days of support (mean 32 days). Most experiments were terminated as a result of correctable mechanical problems. In a separate study of six adult human patients undergoing orthotopic cardiac transplantation, five showed an excellent fit for the Cleveland Clinic-Nimbus total artificial heart. Further studies using chest roentgenograms, chest measurements, and transesophageal echocardiography should help predict fit of the total artificial heart in potential candidates. Initial candidates for a "vented-electric" version of the Cleveland Clinic-Nimbus total artificial heart are patients for whom univentricular (left ventricular assist device) support is not appropriate, but who require mechanical support as a bridge to cardiac transplantation.
Schmitz, Stephanie; Unthan, Kristin; Sedlaczek, Marc; Wald, Felix; Finocchiaro, Thomas; Spiliopoulos, Sotirios; Koerfer, Reiner; Steinseifer, Ulrich
At our institute a total artificial heart is being developed. It is directly actuated by a linear drive in between two ventricles, which comprise membranes to separate the drive and blood flow. A compliance chamber (CC) is needed to reduce pressure peaks in the ventricles and to increase the pump capacity. Therefore, the movement of the membrane is supported by applying a negative pressure to the air volume inside the drive unit. This study presents the development of the implantable CC which is connected to the drive unit of the total artificial hearts (TAH). The anatomical fit of the CC is optimized by analyzing CT data and adapting the outer shape to ensure a proper fit. The pressure peaks are reduced by the additional volume and the flexible membrane of the CC. The validation measurements of change in pressure peaks and flow are performed using the complete TAH system connected to a custom mock circulation loop. Using the CC, the pressure peaks could be damped below 5 mm Hg in the operational range. The flow output was increased by up to 14.8% on the systemic side and 18.2% on the pulmonary side. The described implantable device can be used for upcoming chronic animal trials. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Kaminsky, Radoslav; Kallweit, Stephan; Rossi, Massimiliano; Morbiducci, Umberto; Scalise, Lorenzo; Verdonck, Pascal; Tomasini, Enrico Primo
Through several decades many different models of prosthetic artificial heart valves (PHV) have been designed and optimized in order to enhance hemodynamic properties. These properties are not only material dependent but the major influence results from the mechanical assembly of the particular PHV. For the experimental assessment of the flow through such PHVs particle image velocimetry (PIV) is already an accepted method  due to its noninvasive optical approach and accuracy. Here, we present various modifications of PIV in order to explain, compare and realize which method is the most suitable for the quantification of such flows. The choice of the experimental procedure for testing the PHVs is strongly dependent on the optical access of the designed in-vitro testing loops simulating the human heart and vascular system. The hardware demand and its configuration for, e.g., stereoscopic PIV is much more complex than standard 2D PIV, therefore the conditions and design of the testing loop have to be realized to allow the desired flow measurement. The flow in heart valves as an unsteady periodically generated flow, can be obtained by averaged phaselocked or measurements with high temporal. The properties, advantages and drawbacks of specific PIV techniques to visualize the flow behind a PHV will be discussed.
Demiselle, Julien; Besson, Virginie; Sayegh, Johnny; Subra, Jean-François; Augusto, Jean-François
Total artificial heart (TAH) device is sometimes necessary to treat end stage heart failure (HF). After surgery, renal impairment can occur with the need of renal replacement therapy. We report the case of a 51-year-old man who was treated with conventional hemodialysis (HD) while on support with TAH. The patient underwent HD while on TAH support during 14 months. He benefited from conventional HD, 6 sessions per week. HD sessions were well tolerated, and patient's condition and quality of life improved significantly. The main difficulty was to maintain red blood cell level because of chronic hemolysis due to TAH, which required repetitive blood transfusions, resulting in a high rate of human leukocyte antigen sensitization. Unfortunately, the patient died of mesenteric ischemia due to anticoagulation under dosing. We conclude that HD treatment is possible despite TAH and should be considered in patients with both end stage renal and HF. © 2016 S. Karger AG, Basel.
Karimov, Jamshid H; Moazami, Nader; Sunagawa, Gengo; Kobayashi, Mariko; Byram, Nicole; Sale, Shiva; Such, Kimberly A; Horvath, David J; Golding, Leonard A R; Fukamachi, Kiyotaka
The choice of optimal operative access technique for mechanical circulatory support device implantation ensures successful postoperative outcomes. In this study, we retrospectively evaluated the median sternotomy and lateral thoracotomy incisions for placement of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) in a bovine model. The CFTAH was implanted in 17 calves (Jersey calves; weight range, 77.0-93.9 kg) through a median sternotomy (n = 9) or right thoracotomy (n = 8) for elective chronic implantation periods of 14, 30, or 90 days. Similar preoperative preparation, surgical techniques, and postoperative care were employed. Implantation of the CFTAH was successfully performed in all cases. Both methods provided excellent surgical field visualization. After device connection, however, the median sternotomy approach provided better visualization of the anastomoses and surgical lines for hemostasis confirmation and repair due to easier device displacement, which is severely limited following right thoracotomy. All four animals sacrificed after completion of the planned durations (up to 90 days) were operated through full median sternotomy. Our data demonstrate that both approaches provide excellent initial field visualization. Full median sternotomy provides larger viewing angles at the anastomotic suture line after device connection to inflow and outflow ports. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Takami, Y; Ohtsuka, G; Mueller, J; Ebner, M; Tayama, E; Ohashi, Y; Taylor, D; Fernandes, J; Schima, H; Schmallegger, H; Wolner, E; Nosé, Y
A totally implantable centrifugal artificial heart has been developed using a miniaturized pivot bearing supported centrifugal pump (Gyro PI pump). The authors report current progress in its development. The Gyro PI-601 has a priming volume of 20 ml, weighs 100 g, has a height of 60 mm, and has a diameter of 65 mm. This pump can provide 8 L/min against 150 mmHg at 2,250 rpm. It is driven by an miniaturized DC brushless motor with the coils fixed in a plastic mold that is waterproof and made of titanium (weight, 204 g; height, 18 mm; diameter, 65 mm). In this centrifugal artificial heart, two Gyro PI pumps are implanted independently to replace cardiac function without resecting the native heart. Its anatomic and surgical feasibility were confirmed experimentally. The Gyro PI-601 was implanted as a right or left ventricular assist device in the preperitoneal space of five calves. All five tests proceeded without any thromboembolic symptoms. One of five tests was extended more than 1 month to confirm the long-term feasibility of the Gyro PI-601 pump system. Based on the satisfactory results of the in vivo tests, the material conversion of the Gyro PI from polycarbonate to titanium alloy (Ti-6A1-4V) was undertaken to improve its biocompatibility for long-term implantation.
Slepian, Marvin J.; Alemu, Yared; Soares, João Silva; Smith, Richard G.; Einav, Shmuel; Bluestein, Danny
The SynCardia™ total artificial heart (TAH) is the only FDA-approved TAH in the world. The SynCardia™ TAH is a pneumatically driven, pulsatile system capable of flows of >9 L/min. The TAH is indicated for use as a bridge to transplantation (BTT) in patients at imminent risk of death from non-reversible bi-ventricular failure. In the Pivotal US approval trial the TAH achieved a BTT rate of >79%. Recently a multi-center, post-market approval study similarly demonstrated a comparable BTT rate. A major milestone was recently achieved for the TAH, with over 1100 TAHs having been implanted to date, with the bulk of implantation occurring at an ever increasing rate in the past few years. The TAH is most commonly utilized to save the lives of patients dying from end-stage bi-ventricular heart failure associated with ischemic or non-ischemic dilated cardiomyopathy. Beyond progressive chronic heart failure, the TAH has demonstrated great efficacy in supporting patients with acute irreversible heart failure associated with massive acute myocardial infarction. In recent years several diverse clinical scenarios have also proven to be well served by the TAH including severe heart failure associated with advanced congenital heart disease. failed or burned-out transplants, infiltrative and restrictive cardiomyopathies and failed ventricular assist devices. Looking to the future a major unmet need remains in providing total heart support for children and small adults. As such, the present TAH design must be scaled to fit the smaller patient, while providing equivalent, if not superior flow characteristics, shear profiles and overall device thrombogenicity. To aid in the development of a new “pediatric,” TAH an engineering methodology known as “Device Thrombogenicity Emulation (DTE)”, that we have recently developed and described, is being employed. Recently, to further our engineering understanding of the TAH, as steps towards next generation designs we have: (1
Slepian, Marvin J; Alemu, Yared; Girdhar, Gaurav; Soares, João Silva; Smith, Richard G; Einav, Shmuel; Bluestein, Danny
The SynCardia(™) total artificial heart (TAH) is the only FDA-approved TAH in the world. The SynCardia(™) TAH is a pneumatically driven, pulsatile system capable of flows of >9L/min. The TAH is indicated for use as a bridge to transplantation (BTT) in patients at imminent risk of death from non-reversible bi-ventricular failure. In the Pivotal US approval trial the TAH achieved a BTT rate of >79%. Recently a multi-center, post-market approval study similarly demonstrated a comparable BTT rate. A major milestone was recently achieved for the TAH, with over 1100 TAHs having been implanted to date, with the bulk of implantation occurring at an ever increasing rate in the past few years. The TAH is most commonly utilized to save the lives of patients dying from end-stage bi-ventricular heart failure associated with ischemic or non-ischemic dilated cardiomyopathy. Beyond progressive chronic heart failure, the TAH has demonstrated great efficacy in supporting patients with acute irreversible heart failure associated with massive acute myocardial infarction. In recent years several diverse clinical scenarios have also proven to be well served by the TAH including severe heart failure associated with advanced congenital heart disease. failed or burned-out transplants, infiltrative and restrictive cardiomyopathies and failed ventricular assist devices. Looking to the future a major unmet need remains in providing total heart support for children and small adults. As such, the present TAH design must be scaled to fit the smaller patient, while providing equivalent, if not superior flow characteristics, shear profiles and overall device thrombogenicity. To aid in the development of a new "pediatric," TAH an engineering methodology known as "Device Thrombogenicity Emulation (DTE)", that we have recently developed and described, is being employed. Recently, to further our engineering understanding of the TAH, as steps towards next generation designs we have: (1) assessed of
Kleinheyer, Matthias; Timms, Daniel L; Tansley, Geoffrey D; Nestler, Frank; Greatrex, Nicholas A; Frazier, O Howard; Cohn, William E
Unlike the earlier reciprocating volume displacement-type pumps, rotary blood pumps (RBPs) typically operate at a constant rotational speed and produce continuous outflow. When RBP technology is used in constructing a total artificial heart (TAH), the pressure waveform that the TAH produces is flat, without the rise and fall associated with a normal arterial pulse. Several studies have suggested that pulseless circulation may impair microcirculatory perfusion and the autoregulatory response and may contribute to adverse events such as gastrointestinal bleeding, arteriovenous malformations, and pump thrombosis. It may therefore be beneficial to attempt to reproduce pulsatile output, similar to that generated by the native heart, by rapidly modulating the speed of an RBP impeller. The choice of an appropriate speed profile and control strategy to generate physiologic waveforms while minimizing power consumption and blood trauma becomes a challenge. In this study, pump operation modes with six different speed profiles using the BiVACOR TAH were evaluated in vitro. These modes were compared with respect to: hemodynamic pulsatility, which was quantified as surplus hemodynamic energy (SHE); maximum rate of change of pressure (dP/dt); pulse power index; and motor power consumption as a function of pulse pressure. The results showed that the evaluated variables underwent different trends in response to changes in the speed profile shape. The findings indicated a possible trade-off between SHE levels and flow rate pulsatility related to the relative systolic duration in the speed profile. Furthermore, none of the evaluated measures was sufficient to fully characterize hemodynamic pulsatility. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Kalya, Anantharam; Jaroszewski, Dawn; Pajaro, Octavio; Scott, Robert; Gopalan, Radha; Kasper, Diane; Arabia, Francisco
Cardiac allograft rejection and failure may require mechanical circulatory support as bridge-to-retransplantation. Prognosis in this patient group is poor and implantable ventricular assist devices have had limited success due to organ failure associated with the high dose immunosuppression required to treat ongoing rejection. We present a case from our institution and the world-wide experience utilizing the SynCardia CardioWest Total Artificial Heart (TAH-t; SynCardia Systems, Inc., Tucson, AZ, USA) for replacement of the failing graft, recovery of patient and end-organ failure with ultimate bridge to retransplantation. We present our experience and review of world-wide experience for use of TAH-t in this type patient. © 2013 John Wiley & Sons A/S.
Takatani, S; Shiono, M; Sasaki, T; Sakuma, I; Glueck, J; Sekela, M; Noon, G; Nose, Y; DeBakey, M
A completely implantable, one piece electromechanical total artificial heart (TAH) intended for permanent human use was developed. It consisted of left and right conically shaped pusher-plate blood pumps sandwiching a thin centerpiece with a compact, efficient electromechanical actuator. The actuator consisted of a direct current brushless motor; a planetary roller screw fit the space between the two conically shaped pusher-plates. The rotational motion of the motor was converted to the rectilinear motion of the rollerscrew to displace the left and right pusher-plates in the left master alternate mode. The diameter of the assembled TAH was 97 mm, with a central thickness of 82 mm. The overall weight was 620 g, with a displaced volume of 510 ml. The pump provided flows of 3-8 L/min with a preload of 1-15 mmHg against an afterload of 100 mmHg. The net efficiency ranged from 15% to 18%. This model showed good fit in the pericardial space of heart transplant recipients (body weight, 77 kg).
Khalpey, Zain; Kazui, Toshinobu; Ferng, Alice S; Connell, Alana; Tran, Phat L; Meyer, Mark; Rawashdeh, Badi; Smith, Richard G; Sweitzer, Nancy K; Friedman, Mark; Lick, Scott; Slepian, Marvin J; Copeland, Jack G
The 70 cc total artificial heart (TAH) has been utilized as bridge to transplant (BTT) for biventricular failure. However, the utilization of 70 cc TAH has been limited to large patients for the low output from the pulmonary as well as systemic vein compression after chest closure. Therefore, the 50 cc TAH was developed by SynCardia (Tucson, AZ) to accommodate smaller chest cavity. We report the first TAH exchange from a 70 to 50 cc due to a fit difficulty. The patient failed to be closed with a 70 cc TAH, although the patient met the conventional 70 cc TAH fit criteria. We successfully closed the chest with a 50 cc TAH.
Wada, H; Fukunaga, S; Watari, M; Sakai, H; Sugawara, Y; Ochikubo, H; Imai, K; Shibamura, H; Orihashi, K; Sueda, T; Matsuura, Y
We have made an eccentric roller type total artificial heart (ERTAH). The ERTAH is a positive-displacement device comparable to a DeBakey roller pump. Its left and right outputs are determined by the size of its blood chambers, and the ratio of its left and right output is almost constant. We focused on an interatrial shunt to achieve left-right balance. We have conducted numerical simulation, a mock test, and an acute animal experiment to analyze left-right heart balance during ERTAH operation. Numerical simulation was performed under conditions in which the flow of the left artificial heart was fixed at 6 L/min, the flow of the right artificial heart was varied from 4.8 to 6 L/min, and the interatrial resistance was also varied. The relationship between the interatrial shunt flow rate and the output of the left and right artificial hearts was balanced when the flow of the right artificial heart was at 5.45 L/min. In a mock test, 2 DeBakey roller pumps were connected to the left and right sides of a Donovan mock circulatory system, and an interatrial shunt was created between the inlet ports of the left and right roller pumps. The interatrial resistance of the mock system was varied from 7.7, to 4.3, and to 2.9 mm Hg x min/L when the inner diameter of the interatrial shunt was 6, 8, and 10 mm, respectively. As in the mock test, 2 roller pumps were used to bypass the right and left hearts of a goat weighing 60 kg. The flow rate of the left heart was almost constant (4.7 L/min). The flow of the right heart was approximately 4.1 L/min when the interatrial shunt flow rate was zero. A leading consideration was that the left to left shunt through the bronchial arteries in this goat was approximately 0.6 L/min. In developing the ERTAH, we considered that creating an interatrial shunt between the inlet ports of the ERTAH as well as making a difference between the chamber volumes might be effective in balancing the left-right sides of the artificial heart.
Love, Holley C; Timms, Daniel L; Nestler, Frank; Frazier, O H; Cohn, William E
A mock circulatory loop was constructed to facilitate total artificial heart development. The loop includes many novel features such as a pressure-regulated tank to simulate exercise conditions, controllable systemic and pulmonary vascular resistance to create left-right flow imbalances as seen in postural change and breathing, and a left atrial suction valve. Dual HeartMate II pumps and the BiVACOR® rotary total artificial heart were used to generate pressure and flow data characterizing the flow loop.
Uyama, C; Akutsu, T
The interface geometry of human and artificial hearts was defined. It included: 1) the approximate mitral orifice and mitral orifice planes; 2) the approximate tricuspid orifice and tricuspid orifice planes; 3) the long and short diameters of the aorta; 4) the long and short diameters of the pulmonary artery; and 5) the angles between the mitral orifice and tricuspid orifice planes, as well as the axes of the aorta and pulmonary artery. The orifice plane was defined as a plane such that the sum of the squared distances between the plane and points on the orifice contour was minimized. A standard coordinate system was also defined, whose origin was the centroid of the approximate mitral orifice. Its X-Y plane was the approximate mitral orifice plane. One set of interface parameters was determined using magnetic resonance images of a volunteer's heart. The angle between the approximate mitral orifice plane and tricuspid plane was found to be 19.9 degrees. The areas of the approximate mitral and tricuspid orifices were 1020 and 1655 mm2, respectively. The approximate mitral orifice was covered by a 44 x 40 mm rectangle and the approximate tricuspid orifice was covered by a 59 x 41 mm rectangle. This interface geometry is important, not only in the manufacture of artificial hearts of precise dimensions, but also in avoiding complications due to their long-term use.
Eslamizadeh, Gholamhossein; Barati, Ramin
Early recognition of heart disease plays a vital role in saving lives. Heart murmurs are one of the common heart problems. In this study, Artificial Neural Network (ANN) is trained with Modified Neighbor Annealing (MNA) to classify heart cycles into normal and murmur classes. Heart cycles are separated from heart sounds using wavelet transformer. The network inputs are features extracted from individual heart cycles, and two classification outputs. Classification accuracy of the proposed model is compared with five multilayer perceptron trained with Levenberg-Marquardt, Extreme-learning-machine, back-propagation, simulated-annealing, and neighbor-annealing algorithms. It is also compared with a Self-Organizing Map (SOM) ANN. The proposed model is trained and tested using real heart sounds available in the Pascal database to show the applicability of the proposed scheme. Also, a device to record real heart sounds has been developed and used for comparison purposes too. Based on the results of this study, MNA can be used to produce considerable results as a heart cycle classifier. Copyright © 2017 Elsevier B.V. All rights reserved.
Saito, Yoshiaki; Suzuki, Yasuyuki; Kondo, Norihiro; Kowatari, Ryosuke; Daitoku, Kazuyuki; Minakawa, Masahito; Fukuda, Ikuo
Ventricular assist devices are a potent alternative or bridge therapy to heart transplants for dilated cardiomyopathy patients. However, ventricular assist devices have problems related to biocompatibility, hemocompatibility, and thromboembolic events, especially in younger patients. The present study examined the hemodynamic effects of a direct cardiac compression device using circumferential artificial rubber muscles in a young swine model of dilated cardiomyopathy. Dilated cardiomyopathy was established in 6 pigs (6-8 weeks of rapid right ventricular pacing; average weight, 22.6 ± 2.1 kg). The device was designed using pneumatic rubber muscles (Fluidic Muscle, Festo). Hemodynamic parameters were monitored under baseline conditions, after the assistance, and after inducing ventricular fibrillation. Hemodynamic data were acquired using a PiCCO, multilumened thermodilution catheter in the pulmonary artery, left ventricular pressure monitoring, and epicardial echocardiography. Direct epicardial assistance resulted in a significant improvement in hemodynamic data. Cardiac output improved from 1.39 ± 0.24 L/min to 1.96 ± 0.46 (p = 0.02). Stroke volume (14.5 ± 3.2 mL versus 20.1 ± 4.3 ml, p<0.01) and ejection fraction (25.2 ± 3.6% versus 47.7 ± 7.8%, p<0.01) also improved after assistance. After inducing ventricular fibrillation, cardiac output was maintained at 1.33 ± 0.28 L/min. Use of a circumferential direct epicardial assistant device resulted in improvement in hemodynamic data in a dilated cardiomyopathy model. Although there is still a need for improvements in device components, the direct cardiac assist device may be a good alternative to recent heart failure device therapies.
Hamburg, E.; Vunder, V.; Johanson, U.; Kaasik, F.; Aabloo, A.
We report on a multifunctional four-finger gripper for soft robotics, suitable for performing delicate manipulation tasks. The gripping device is comprised of separately driven gripping and lifting mechanisms, both made from a separate single piece of smart material - ionic capacitive laminate (ICL) also known as artificial muscle. Compared to other similar devices the relatively high force output of the ICL material allows one to construct a device able to grab and lift objects exceeding multiple times its own weight. Due to flexible design of ICL grips, the device is able to adapt the complex shapes of different objects and allows grasping single or multiple objects simultaneously without damage. The performance of the gripper is evaluated in two different configurations: a) the ultimate grasping strength of the gripping hand; and b) the maximum lifting force of the lifting actuator. The ICL is composed of three main layers: a porous membrane consisting of non-ionic polymer poly(vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP), ionic liquid 1-ethyl-3-methylimidazolium trifluoromethane-sulfonate (EMITFS), and a reinforcing layer of woven fiberglass cloth. Both sides of the membrane are coated with a carbonaceous electrode. The electrodes are additionally covered with thin gold layers, serving as current collectors. Device made of this material operates silently, requires low driving voltage (<3 V), and is suitable for performing tasks in open air environment.
Frazier, O H; Cohn, William E; Tuzun, Egemen; Winkler, Jo Anna; Gregoric, Igor D
The development and clinical use of continuous-flow left ventricular assist devices (LVADs) stimulated our interest in developing a total heart replacement with continuous-flow rotary blood pumps. We constructed a continuous-flow total artificial heart (CFTAH) from 2 HeartMate II axial-flow LVADs and used this CFTAH to replace the native heart of a calf. The purpose of this experiment was to study the effects of total continuous flow on physiologic parameters at rest and during exercise after the animal recovered from surgery. We monitored pulmonary and systemic pump performance, and we assessed arterial blood gases, hemodynamic and biochemical variables, and neurohormone levels during the 7 weeks of CFTAH support. At day 36 after CFTAH implantation, the calf was exercised on a treadmill at increasing speeds for 40 minutes; total oxygen consumption, pump flow, blood pressure, and respiratory rate were monitored. Baseline hematologic levels were altered postoperatively but returned to normal by 2 weeks. We saw no signs of hemolysis or thrombosis during CFTAH support. The calf had a normal physiologic response to treadmill exercise. The animal gained weight and appeared to function normally during the study. The CFTAH operated within design specifications throughout the study. Homeostasis, end-organ and vasomotor function, and the ability to exercise are not adversely affected by 7 weeks of totally pulseless circulation in a calf.
Frazier, O. H.; Cohn, William E.; Tuzun, Egemen; Winkler, Jo Anna; Gregoric, Igor D.
The development and clinical use of continuous-flow left ventricular assist devices (LVADs) stimulated our interest in developing a total heart replacement with continuous-flow rotary blood pumps. We constructed a continuous-flow total artificial heart (CFTAH) from 2 HeartMate II axial-flow LVADs and used this CFTAH to replace the native heart of a calf. The purpose of this experiment was to study the effects of total continuous flow on physiologic parameters at rest and during exercise after the animal recovered from surgery. We monitored pulmonary and systemic pump performance, and we assessed arterial blood gases, hemodynamic and biochemical variables, and neurohormone levels during the 7 weeks of CFTAH support. At day 36 after CFTAH implantation, the calf was exercised on a treadmill at increasing speeds for 40 minutes; total oxygen consumption, pump flow, blood pressure, and respiratory rate were monitored. Baseline hematologic levels were altered postoperatively but returned to normal by 2 weeks. We saw no signs of hemolysis or thrombosis during CFTAH support. The calf had a normal physiologic response to treadmill exercise. The animal gained weight and appeared to function normally during the study. The CFTAH operated within design specifications throughout the study. Homeostasis, end-organ and vasomotor function, and the ability to exercise are not adversely affected by 7 weeks of totally pulseless circulation in a calf. PMID:20069083
Copeland, Jack G; Smith, Richard G; Arabia, Francisco A; Nolan, Paul E; McClellan, Douglas; Tsau, Pei H; Sethi, Gulshan K; Bose, Raj K; Banchy, Mary E; Covington, Diane L; Slepian, Marvin J
The SynCardia CardioWest total artificial heart (CardioWest TAH) is a biventricular, orthotopic, pneumatic, pulsatile blood pump driven by an external console. For each ventricle, the length of the blood-flow path is shorter and the inflow and outflow valves are larger than in any other bridge-to-transplant device, resulting in greater blood flow at smaller pre-load. Such a device should be optimal for bridging transplant candidates who have biventricular failure and for whom all other therapies have failed. From January 1, 1993, to April 1, 2002, we prospectively studied 62 consecutive CardioWest TAH implant recipients to document safety and efficacy in bridge to transplantation. We used multisystem monitoring and multidrug therapy for anti-coagulation in 58 patients starting September 1, 1994. Before implantation, patients were critically ill with biventricular heart failure. Mortality in this group from the time of implantation until transplantation was 23%. Causes of death during device support included multi-organ failure (6), sepsis (3), and valve entrapment (2). Forty-eight patients underwent transplantation (77%). Forty-two survived to hospital discharge (68% of the total, 88% of those undergoing transplantation). Adverse events included bleeding (20%), device malfunction (5%), fit complications (3%), mediastinal infections (5%), visceral embolus (1.6%), and stroke during support (1.6%). The linearized stroke rate was 0.068 events per patient-year. Sixty-eight percent of critically ill transplant candidates for whom medical therapy failed were bridged to transplantation with the CardioWest TAH and survived long-term. Most deaths that occurred during device support were related to pre-implant problems. Infection and stroke were rare events. Therefore, we recommend the CardioWest TAH as the biventricular bridge-to-transplant device of choice.
Karimov, Jamshid H; Horvath, David J; Byram, Nicole; Sunagawa, Gengo; Grady, Patrick; Sinkewich, Martin; Moazami, Nader; Sale, Shiva; Golding, Leonard A R; Fukamachi, Kiyotaka
The unique device architecture of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) requires dedicated and specific air-removal techniques during device implantation in vivo. These procedures comprise special surgical techniques and intraoperative manipulations, as well as engineering design changes and optimizations to the device itself. The current study evaluated the optimal air-removal techniques during the Cleveland Clinic double-ended centrifugal CFTAH in vivo implants (n = 17). Techniques and pump design iterations consisted of developing a priming method for the device and the use of built-in deairing ports in the early cases (n = 5). In the remaining cases (n = 12), deairing ports were not used. Dedicated air-removal ports were not considered an essential design requirement, and such ports may represent an additional risk for pump thrombosis. Careful passive deairing was found to be an effective measure with a centrifugal pump of this design. In this report, the techniques and design changes that were made during this CFTAH development program to enable effective residual air removal and prevention of air embolism during in vivo device implantation are explained.
Raguin, Thibaut; Dupret-Bories, Agnès; Debry, Christian
Research has been fighting against organ failure and shortage of donations by supplying artificial organs for many years. With the raise of new technologies, tissue engineering and regenerative medicine, many organs can benefit of an artificial equivalent: thanks to retinal implants some blind people can visualize stimuli, an artificial heart can be proposed in case of cardiac failure while awaiting for a heart transplant, artificial larynx enables laryngectomy patients to an almost normal life, while the diabetic can get a glycemic self-regulation controlled by smartphones with an artificial device. Dialysis devices become portable, as well as the oxygenation systems for terminal respiratory failure. Bright prospects are being explored or might emerge in a near future. However, the retrospective assessment of putative side effects is not yet sufficient. Finally, the cost of these new devices is significant even if the advent of three dimensional printers may reduce it. © 2017 médecine/sciences – Inserm.
Englert, Joseph A. R.; Davis, Jennifer A.; Krim, Selim R.
Background: Heart transplantation remains the definitive therapy for patients with advanced heart failure; however, owing to limited donor organ availability and long wait times, continuous-flow left ventricular assist devices (LVADs) have become standard therapy. Methods: This review summarizes the history, progression, function, and basic management of LVADs. Additionally, we provide some clinical pearls and important caveats for managing this unique patient population. Results: Currently, the most common LVADs being implanted in the United States are second- and third-generation devices, the HeartMate II (Thoratec Corp., St. Jude Medical) and the HeartWare HVAD (HeartWare International, Inc.). A newer third-generation pump, the HeartMate III (Thoratec Corp., St. Jude Medical), is designed to create an artificial pulse and is currently under investigation in the United States. Conclusion: LVAD use is promising, will continue to grow, and has become standard therapy for advanced heart failure as a bridge to recovery, as destination therapy, and as a bridge to transplantation. PMID:27660575
CESARIO, DAVID; KEDIA, ROHIT; DESAI, NIRAV; ABOULHOSN, JAMIL; USLAN, DANIEL; BOYLE, NOEL; FUJIMURA, OSAMU; SHEHATA, MICHAEL; BUCH, ERIC; SHIVKUMAR, KALYANAM
Background Device extraction is a critical component in the treatment of patients with device-related infections. Due to complex anatomic considerations, device extraction in adults with congenital heart disease presents unique challenges to the electrophysiologist. Methods Here, we present a series of device-extraction cases performed in patients with transposition of the great arteries status post either Mustard or Senning surgical procedures that subsequently had permanent pacemakers placed and ultimately developed device-related infections. Results All of these patients eventually underwent successful laser extractions of their infected devices resulting in complete removal of all hardware and resolution of their infections. Conclusions These cases illustrate that endovascular device extraction has been safely and effectively performed in adult patients with congenital heart disease, though further studies are needed to determine the procedural risks and success rates of this procedure in this patient population. PMID:19272064
Feng, Jun; Cohn, William E.; Parnis, Steven M.; Sodha, Neel R.; Clements, Richard T.; Sellke, Nicholas; Frazier, O. Howard; Sellke, Frank W.
Background We tested the short-term effects of completely non-pulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an animal model on peripheral vascular permeability. Methods Ten calves underwent cardiac replacement with two HeartMate III continuous-flow rotary pumps. In five calves, the pump speed was rapidly modulated to impart a low-frequency pulse pressure in the physiologic range (10–25 mmHg) at a rate of 40 pulses per minute (PP). The remaining 5 calves were supported with a pulseless systemic circulation and no modulation of pump speed (NP). Skeletal muscle biopsies were obtained before cardiac replacement (baseline) and on postoperative days (POD) 1, 7 and 14. Skeletal muscle tissue water content was measured and morphological alterations of skeletal muscle were assessed. VE-cadherin, phospho-VE-cadherin and CD31 were analyzed by immuno-histochemistry. Results There were no significant changes in tissue water content and skeletal muscle morphology within group or between groups at baseline, POD 1, 7 and 14, respectively. There were no significant alterations in the expression/distribution of VE-cadherin, phospho-VE cadherin and CD31 in skeletal muscle vasculature at baseline, POD 1, 7 and 14 within each group or between the two groups, respectively. Although continuous-flow total artificial heart (CFTAH) with or without a pulse pressure caused slight increase in tissue water content and histological damage scores at POD 7 and 14, it failed to reach statistical significance. Conclusions There was no significant adherens-junction protein degradation and phosphorylation in calf skeletal muscle microvasculature after CFTAH implantation, suggesting that short term of CFTAH with or without pulse pressure did not cause peripheral endothelial injury and did not increase the peripheral microvascular permeability. PMID:26188957
Feng, Jun; Cohn, William E; Parnis, Steven M; Sodha, Neel R; Clements, Richard T; Sellke, Nicholas; Frazier, O Howard; Sellke, Frank W
We tested the short-term effects of completely nonpulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an animal model on peripheral vascular permeability. Ten calves underwent cardiac replacement with two HeartMate III continuous-flow rotary pumps. In five calves, the pump speed was rapidly modulated to impart a low-frequency pulse pressure in the physiologic range (10-25 mm Hg) at a rate of 40 pulses per minute (PP). The remaining five calves were supported with a pulseless systemic circulation and no modulation of pump speed (NP). Skeletal muscle biopsies were obtained before cardiac replacement (baseline) and on postoperative days (PODs) 1, 7, and 14. Skeletal muscle-tissue water content was measured, and morphologic alterations of skeletal muscle were assessed. VE-cadherin, phospho-VE-cadherin, and CD31 were analyzed by immunohistochemistry. There were no significant changes in tissue water content and skeletal muscle morphology within group or between groups at baseline, PODs 1, 7, and 14, respectively. There were no significant alterations in the expression and/or distribution of VE-cadherin, phospho-VE-cadherin, and CD31 in skeletal muscle vasculature at baseline, PODs 1, 7, and 14 within each group or between the two groups, respectively. Although continuous-flow total artificial heart (CFTAH) with or without a pulse pressure caused slight increase in tissue water content and histologic damage scores at PODs 7 and 14, it failed to reach statistical significance. There was no significant adherens-junction protein degradation and phosphorylation in calf skeletal muscle microvasculature after CFTAH implantation, suggesting that short term of CFTAH with or without pulse pressure did not cause peripheral endothelial injury and did not increase the peripheral microvascular permeability. Copyright © 2015 Elsevier Inc. All rights reserved.
Karimov, Jamshid H; Grady, Patrick; Sinkewich, Martin; Sunagawa, Gengo; Dessoffy, Raymond; Byram, Nicole; Moazami, Nader; Fukamachi, Kiyotaka
The benefit of whole-body hypothermia in preventing ischemic injury during cardiac surgical operations is well documented. However, application of hypothermia during in vivo total artificial heart implantation has not become widespread because of limited understanding of the proper techniques and restrictions implied by constitutional and physiological characteristics specific to each animal model. Similarly, the literature on hypothermic set-up in total artificial heart implantation has also been limited. Herein we present our experience using hypothermia in bovine models implanted with the Cleveland Clinic continuous-flow total artificial heart.
Muradbegovic, Mirza; Taub, Steven; Rizzo, Elena; von Segesser, Ludwig K; Tozzi, Piergiorgio
Ventricular assist devices (VADs) are used in treatment for terminal heart failure or as a bridge to transplantation. We created biVAD using the artificial muscles (AMs) that supports both ventricles at the same time. We developed the test bench (TB) as the in vitro evaluating system to enable the measurement of performance. The biVAD exerts different pressure between left and right ventricle like the heart physiologically does. The heart model based on child's heart was constructed in silicone. This model was fitted with the biVAD. Two pipettes containing water with an ultrasonic sensor placed on top of each and attached to ventricles reproduced the preload and the after load of each ventricle by the real-time measurement of the fluid height variation proportionally to the exerted pressure. The LabVIEW software extrapolated the displaced volume and the pressure generated by each side of our biVAD. The development of a standardized protocol permitted the validation of the TB for in vitro evaluation, measurement of the performances of the AM biVAD herein, and reproducibility of data.
Homma, Akihiko; Taenaka, Yoshiyuki; Tatsumi, Eisuke; Takewa, Yoshiaki; Mizuno, Toshihide; Shioya, Kyoko; Lee, Hwan Sung; Tsukiya, Tomonori; Kakuta, Yukihide; Katagiri, Nobumasa; Nishinaka, Tomohiro; Koshiji, Kohji
An electrohydraulic total artificial heart (EHTAH) system has been developed. The EHTAH system consists of diaphragm-type blood pumps, an 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 which 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 decreased to 872 ml and 2492g, 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 87kg. In the longest case, the ca1f with the pump unit survived for 87 days and the calf with the EHTAH system survived for 70 days. The EHTAH system was powered by the TETS, and was powered everyday 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.
Taenaka, Y; Sekii, H; Tatsumi, E; Nakatani, T; Sasaki, E; Yagura, A; Akagi, H; Masuzawa, T; Goto, M; Matsuo, Y
An electrohydraulic total artificial heart (EHTAH) system, consisting of a separately placed actuator and blood pumps with good anatomic fit, was designed. In the actuator is a brushless DC motor sandwiched between two metal bellows or two pusher-plate pumps connected with the blood pumps by polyvinylchloride tubes. A roller-screw system coupled with the bellows is used for alternative pumping, and silicone oil transmits the action. The pumps are elliptical, and the right pump has a flatter and longer shape than the left to fit the extremely short distance between the right atrium and the sternum. To evaluate in vivo performance, the pumps were implanted as a pneumatic system in a calf weighing 53 kg and three goats weighing 54-55 kg. The pump fit well in the animals, and the calf survived for 111 days, and one goat was alive for 8 days. The EHTAH system could provide an output of 6 L/min with pusher-plate pumps as oil chambers on in vitro evaluation. This system could become one of the most suitable approaches for a totally implantable system.
Wipf, S L
A positive displacement pump with six rotary pistons was proposed as an artificial heart. The pump's design was characterized by high symmetry and compactness. Thus, a spherical volume of 4 1/4 inch diameter sufficed for a pump delivering 10 L/min at 120 pulses/min with the pistons turning at 30 rpm. The pistons and four connecting gears were the only moving parts. The pump functions in two separate halves as left and right ventricles, with two of the six pistons each having inlet and outlet passages, and one of them replacing mitral and pulmonary valves with the other, tricuspid and aortic valves. The function of the intraventricular septum was provided by the other four pistons whose interiors also accommodated driving motors each capable of 0.4 Nm torque for a combined power of 5 watts. There were no stagnant regions in the pumping volume, and at all internal surfaces in contact with blood, there was periodic shear stress not exceeding approximately 300 Pa.
Meier, D; Wernicke, J T; Orime, Y; Takatani, S; Tasai, K; Damm, G; Naito, K; Mizuguchi, K; Makinouchi, K; Glueck, J
To obtain an optimal design of the left blood chamber of the total artificial heart (TAH), flow visualization studies were performed. Information on velocities in critical areas of the left chamber was gathered using sectional pulsed laser light. The flow patterns on the entire pumping duration were photographed frame by frame. The inflow port, the opposite of the inflow and outflow of the pump (bottom area), and the diaphragm/housing junction were the focal areas. The pump conditions, such as chamber pressure, preload and afterload pressure, pumping rate and roller screw, and displacement were recorded. Major stagnations and a low washout effect were observed in the bottom region. The closing of the inflow valve was irregular. In order to solve this problem, the inflow valve angle was changed 20 degrees. A comparison study showed a better valve closing characteristic, and no stagnation areas were observed with this new valve angle. Various velocity profiles confirmed the results. The valve closing characteristics is described in relationship to back flow.
Johnson, K E; Liska, M B; Joyce, L D; Emery, R W
Eleven models of total artificial hearts (TAHs) have been used for transient or permanent circulatory support in patients with failing hearts. From April 4, 1969 to July 1, 1991, 230 TAHs were used in 226 patients (four patients received a second TAH) at 39 centers worldwide. Five patients received a Symbion TAH as a permanent circulatory support device; the remaining 221 received TAHs as bridges to cardiac transplantation. The principal investigators received written requests for demographic and clinical information after each implant and annually thereafter to assess survival. The mean patient age (+/- SD) was 43 +/- 12 years (range, 13-69 years); 88% of patients were men. The primary indications for implantation were deterioration while on a transplant waiting list (34%) and acute cardiogenic shock (33%). The duration of implantation ranged from < 1 to 603 days; 65% received heart transplants. The incidence of infection and embolic events occurring during implantation times were 36% and 9%, respectively (stroke, 5%; transient ischemic attacks 4%). Most deaths were caused by sepsis (33%) and multiorgan failure (32%) during the implantation period; sepsis (36%) and rejection of the donor heart (19%) were responsible for most deaths in patients who died after transplantation. The 1 year survival rate was 37% for all patients receiving a device and 50% for those who received a transplanted organ. In the overall Symbion TAH population (187 patients), 40% survived 1 year and 56% of the transplanted group survived 1 year; 39 non-Symbion TAH implants resulted in one long-term survivor (3%).(ABSTRACT TRUNCATED AT 250 WORDS)
Glynn, Jeremy; Song, Howard; Hull, Bryan; Withers, Stanley; Gelow, Jill; Mudd, James; Starr, Albert; Wampler, Richard
Widespread use of heart transplantation is limited by the scarcity of donor organs. Total artificial heart (TAH) development has been pursued to address this shortage, especially to treat patients who require biventricular support. We have developed a novel TAH that utilizes a continuously spinning rotor that shuttles between two positions to provide pulsatile, alternating blood flow to the systemic and pulmonary circulations without artificial valves. Flow rates and pressures generated by the TAH are controlled by adjusting rotor speed, cycle frequency, and the proportion of each cycle spent pumping to either circulation. To validate the design, a TAH prototype was placed in a mock circulatory loop that simulates vascular resistance, pressure, and compliance in normal and pathophysiologic conditions. At a systemic blood pressure of 120/80 mm Hg, nominal TAH output was 7.4 L/min with instantaneous flows reaching 17 L/min. Pulmonary artery, and left and right atrial pressures were all maintained within normal ranges. To simulate implant into a patient with severe pulmonary hypertension, the pulmonary vascular resistance of the mock loop was increased to 7.5 Wood units. By increasing pump speed to the pulmonary circulation, cardiac output could be maintained at 7.4 L/min as mean pulmonary artery pressure increased to 56 mm Hg while systemic blood pressures remained normal. This in vitro testing of a novel, shuttling TAH demonstrated that cardiac output could be maintained across a range of pathophysiologic conditions including pulmonary hypertension. These experiments serve as a proof-of-concept for the design, which has proceeded to in vivo testing. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Ronco, C; Davenport, A; Gura, V
New directions in dialysis research include cheaper treatments, home based therapies and simpler methods of blood purification. These objectives may be probably obtained with innovations in the field of artificial kidney through the utilization of new disciplines such as miniaturization, microfluidics, nanotechnology. This research may lead to a new era of dialysis in which the new challenges are transportability, wearability and why not the possibility to develop implantable devices. Although we are not there yet, a new series of papers have recently been published disclosing interesting and promising results on the application of wearable ultrafiltration systems (WUF) and wearable artificial kidneys (WAK). Some of them use extracorporeal blood cleansing as a method of blood purification while others use peritoneal dialysis as a treatment modality (ViWAK and AWAK.) A special mention deserves the wearable/portable ultrafiltration system for the therapy of overhydration and congestive heart failure (WAKMAN). This system will allow dehospitalization and treatment of patients with less comorbidity and improved tolerance. On the way to the wearable artificial kidney, new discoveries have been made such as a complete system for hemofiltration in newborns (CARPEDIEM). The neonate in fact is the typical patient who may benefit from miniaturization of the dialysis circuit. This review analyzes the rationale for such endeavour and the challenges to overcome in order to make possible a true ambulatory dialysis treatment. Some initial results with these new devices are presented. We would like to stimulate a collaborative effort to make a quantum leap in technology making the wearable artificial kidney a reality rather than a dream.
Snyder, A J; Rosenberg, G; Reibson, J; Donachy, J H; Prophet, G A; Arenas, J; Daily, B; McGary, S; Kawaguchi, O; Quinn, R
An electric motor driven orthotopic artificial heart was implanted in a 110 kg female Holstein calf as part of a series of 12 such implants intended to demonstrate the in vivo durability and compatibility of the device. The device uses pusher plates set into motion by a reversing brushless DC motor and roller screw to alternately eject two cylindrical sac type blood pumps. The pumps use Bjork-Shiley Delrindisc convexo-concave or monostrut valves. The left pump provides an 88-90 ml dynamic stroke volume. Woven Dacron grafts and polyurethane coated Dacron/Lycra cuffs are used to attach the device to the major arteries and atria, respectively. A polyurethane conduit and anchoring skin button bring motor wires percutaneously to an extracorporeal controller. The controller provides balanced cardiac output sensitive to atrial or aortic pressures, without operator intervention. The system is hermetically sealed and uses a simple compliance sac to maintain thoracic pressure between the pumps. The calf recovered uneventfully from surgery and thrived thereafter. She was killed on the 388th post-operative day because of worsening cardiac insufficiency. The previous three operative survivors in this series lived 131, 134, and 204 days. These results indicate the device's good potential for durability and body compatibility.
Arabia, F A; Smith, R G; Rose, D S; Arzouman, D A; Sethi, G K; Copeland, J G
Circulatory assist devices as bridge to heart transplantation have become more important as the number of possible recipients has increased and the number of donors remains stable. The number of patients successfully bridged and discharged home after transplantation was determined for the Novacor Left Ventricular Assist System (Baxter Healthcare Corp., Oakland, CA) (LVAS), console and wearable; the TCI Left Ventricular Assist Device (Thermo Cardio Systems Inc., Woburn, MA) (LVAD), pneumatic and electric; the Thoratec LVAD and Biventricular Assist Device (Thoratec Lab Co., Berkeley, CA) (BIVAD); and the CardioWest total artificial heart (CardioWest Tech. Inc., Tuscon, AZ) (TAH). A total of 1,286 devices (14% Novacor console, 14% Novacor wearable, 35% TCI pneumatic, 4% TCI electric, 10% thoratec LVAD, 19% Thoratec BIVAD, and 4% CardioWest TAH) were implanted worldwide since 1984. A total of 776 (60%) patients reached heart transplantation and 687 patients (88.5% of those transplanted) were discharged home. The individual success rate for each device to bridge a patient to heart transplantation and be discharged home is as follows: Novacor LVAS console, 90%; Novacor LVAS wearable, 92%; TCI LVAD pneumatic, 89%; TCI LVAD electric, 89%; Thoratec LVAD, 93%; Thoratec BIVAD, 81%; and CardioWest TAH, 92%. The success rate with all the available systems to bridge a patient to heart transplantation and be discharged home is similar for all devices. The criteria used to determine which system to be used should be individualized for each patient. Some of the factors that should be considered in making a decision on which device to use should include anticoagulation, univentricular vs biventricular failure, mobility, protocol to discharge home, and size of the patient.
Kim, H C; Khanwilkar, P S; Bearnson, G B; Olsen, D B
An automatic physiological control system for the actively filled, alternately pumped ventricles of the volumetrically coupled, electrohydraulic total artificial heart (EHTAH) was developed for long-term use. The automatic control system must ensure that the device: 1) maintains a physiological response of cardiac output, 2) compensates for an nonphysiological condition, and 3) is stable, reliable, and operates at a high power efficiency. The developed automatic control system met these requirements both in vitro, in week-long continuous mock circulation tests, and in vivo, in acute open-chested animals (calves). Satisfactory results were also obtained in a series of chronic animal experiments, including 21 days of continuous operation of the fully automatic control mode, and 138 days of operation in a manual mode, in a 159-day calf implant.
Guidi, G; Pettenati, M C; Miniati, R; Iadanza, E
In this paper we describe an Heart Failure analysis Dashboard that, combined with a handy device for the automatic acquisition of a set of patient's clinical parameters, allows to support telemonitoring functions. The Dashboard's intelligent core is a Computer Decision Support System designed to assist the clinical decision of non-specialist caring personnel, and it is based on three functional parts: Diagnosis, Prognosis, and Follow-up management. Four Artificial Intelligence-based techniques are compared for providing diagnosis function: a Neural Network, a Support Vector Machine, a Classification Tree and a Fuzzy Expert System whose rules are produced by a Genetic Algorithm. State of the art algorithms are used to support a score-based prognosis function. The patient's Follow-up is used to refine the diagnosis.
A finite-difference, three-dimensional incompressible Navier-Stokes formulation to calculate the flow through turbopump components is utilized. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. Both steady and unsteady flow calculations can be performed using the current algorithm. In this work, the equations are solved in steadily rotating reference frames by using the steady-state formulation in order to simulate the flow through a turbopump inducer. Eddy viscosity is computed by using an algebraic mixing-length turbulence model. Numerical results are compared with experimental measurements and a good agreement is found between the two. Included in the appendix is a paper on incompressible viscous flow through artificial heart devices with moving boundaries. Time-accurate calculations, such as impeller and diffusor interaction, will be reported in future work.
Shah, Keyur B; Thanavaro, Kristin L; Tang, Daniel G; Quader, Mohammed A; Mankad, Anit K; Tchoukina, Inna; Thacker, Leroy R; Smallfield, Melissa C; Katlaps, Gundars; Hess, Michael L; Cooke, Richard H; Kasirajan, Vigneshwar
Insufficient data delineate outcomes for Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 1 patients with the total artificial heart (TAH). We studied 66 consecutive patients implanted with the TAH at our institution from 2006 through 2012 and compared outcome by INTERMACS profile. INTERMACS profiles were adjudicated retrospectively by a reviewer blinded to clinical outcomes. Survival after TAH implantation at 6 and 12 months was 76% and 71%, respectively. INTERMACS profile 1 patients had decreased 6-month survival on the device compared with those in profiles 2-4 (74% vs 95%, log rank: P = .015). For the 50 patients surviving to heart transplantation, the 1-year posttransplant survival was 82%. There was no difference in 1-year survival when comparing patients in the INTERMACS 1 profile with less severe profiles (79% vs 84%; log rank test P = .7; hazard ratio [confidence interval] 1.3 [0.3-4.8]). Patients implanted with the TAH as INTERMACS profile 1 had reduced survival to transplantation compared with less sick profiles. INTERMACS profile at the time of TAH implantation did not affect 1-year survival after heart transplantation. Copyright © 2016 Elsevier Inc. All rights reserved.
Ruzza, A; Czer, L S C; De Robertis, M; Luthringer, D; Moriguchi, J; Kobashigawa, J; Trento, A; Arabia, F
Chagas disease (CD) is becoming an increasingly recognized cause of dilated cardiomyopathy outside of Latin America, where it is endemic, due to population shifts and migration. Heart transplantation (HTx) is a therapeutic option for end-stage cardiomyopathy due to CD, but may be considered a relative contraindication due to potential reactivation of the causative organism with immunosuppression therapy. The total artificial heart (TAH) can provide mechanical circulatory support in decompensated patients with severe biventricular dysfunction until the time of HTx, while avoiding immunosuppressive therapy and removing the organ most affected by the causative organism. We report herein a patient with CD and severe biventricular dysfunction, who had mechanical circulatory support with a TAH for more than 6 months, followed by successful orthotopic HTx and treatment with benznidazole for 3 months. The patient had no evidence of recurrent disease in the transplanted heart based on endomyocardial biopsy up to 1 year post-transplantation, and remains alive more than 30 months after insertion of a TAH and 24 months after HTx. Copyright © 2016 Elsevier Inc. All rights reserved.
Orime, Y; Takatani, S; Shiono, M; Sasaki, T; Minato, N; Ohara, Y; Swenson, C A; Noon, G P; Nosé, Y; DeBakey, M E
A versatile, one-piece total artificial heart (TAH) system that can be driven by either an electromechanical acutator (EM-TAH) or a pneumatic source (P-TAH) has been developed. The common units for both TAHs are the conically shaped left and right pusher-plate-type pumps (63 ml SV) that sandwich a thin centerpiece (18 mm) having a respective actuator. The EM actuator, mounted in the middle of the centerpiece, consists of a direct-current brushless motor and a roller screw while the pneumatic actuator consists of a low-pressure air source. The outer diameter of the pumping unit is 97 mm with its central thickness being 82 mm; overall volume is 510 cc. The TAH is operated in the left master alternative ejection mode with the left pump fill signal. High-flex-life Hexsyn rubber is used as the diaphragm, and the blood-contacting surface is coated with dry gelatin. The TAH can provide 3-8 L/min flow with a preload of 1-10 mm Hg against 100 mm Hg afterload. Anatomical fit of the pumping unit has been demonstrated in the pericardial space of 26 heart transplant recipients with average body weight of 78 kg. To date, 2 P-TAH and 4 EM-TAH (1 week) implantations were performed in 80-100 kg calves demonstrating excellent anatomical fit, controllability, and biocompatibility. This versatile TAH is suitable for a bridge to transplantation or permanent heart replacement.
Yambe, T; Nanka, S; Naganuma, S; Kobayashi, S; Nitta, S; Fukuju, T; Miura, M; Uchida, N; Tabayashi, K; Tanaka, A; Takayasu, M; Abe, K; Takayasu, H; Yoshizawa, M; Takeda, H
We have studied the fluctuations of an artificial circulation for the analysis of the physiological aspects; however, the conventionally used fast Fourier transform (FFT) method cannot separate harmonic oscillations, such as respiratory and Mayer waves, from the 1/f fluctuation, which has been though to represent underlying fractal dynamics. Fractal structure was shown in the strange attractor with chaotic dynamics, which is thought to be a flexible and intelligent system. In this study, the coarse-graining spectral analyzing (CGSA) method was utilized to quantitatively evaluate the proportion of the 1/f fluctuation in the total power in the frequency domain and to analyze artificial circulation in the whole system. We implanted two pneumatically actuated ventricular assist devices as biventricular bypasses (BVBs) in chronic animal experiments using 4 healthy adult goats. To compare the natural and prosthetic circulation of each experimental animal, the BVB-type complete prosthetic circulation model with electrically induced ventricular fibrillation was adopted. All hemodynamic parameters of natural and prosthetic circulation were recorded under awake conditions and calculated with the use of a personal computer. With the use of the CGSA method, time-series data of the hemodynamics were analyzed and fractal percentages, extracting the 1/f fluctuation from a given time series, were calculated. Fractal percentages of the arterial blood pressure were 85.8 +/- 10.7% and 82.0 +/- 7.3% with natural and artificial circulation, respectively (not significant [NS]). 1/f fluctuation showed the characteristics of being fractal in a time series. The fractal structure showed robustness and error resistance in nonlinear dynamics. Therefore, our results suggest that the circulatory regulatory system of the artificial heart may have desirable characteristics such as error resistance.
Lee, H; Taenaka, Y
In previous studies, we investigated the cavitation phenomenon in a mechanical heart valve using an electro-hydraulic total artificial heart. With this system, a 50% glycerin solution kept at 37 degrees C was used as the working fluid. We reported that most of the cavitation bubbles were observed near the valve stop and were caused by the squeeze flow. However, in these studies, the effect of the partial pressure of CO(2) on the mechanical heart valve cavitation was neglected. In this study, in order to investigate the effect of the partial pressure of CO(2) on mechanical heart valve cavitation using an electro-hydraulic total artificial heart, we controlled the partial pressure of the CO(2) in vitro. A 25-mm Medtronic Hall valve was installed in the mitral position of an electro-hydraulic total artificial heart. In order to quantify the mechanical heart valve cavitation, we used a high-speed camera. Even though cavitation intensity slightly increased with increases in the PCO(2) at heart rates of 60, 70 and 100 bpm, throughout the experiment, there was no significant difference between the PCO(2) and cavitation intensity.
Tsujimura, Shinichi; Kuwabara, Takashi; Koguchi, Harutoshi; Yamane, Takashi; Tsutsui, Tatsuo; Sankai, Yoshiyuki
To realize safe and effective medical treatment for patients with implantable artificial hearts, we have developed a smart artificial heart (SAH). The SAH can grasp the mechanical condition of the artificial heart and the physiological condition of the patient. The purpose of this study is to develop a failure detection system based on the vibration signal from artificial heart in order to enhance the ability of failure detection for the SAH. We suppose this vibration signal reflects not only the mechanical condition of the artificial heart but also a part of the physiological condition of the patient. The developed failure detection system is composed of a vibration sensor unit and a failure detection algorithm. The algorithm has a standard frequency pattern, which is made from the vibration signal of good condition of both the artificial heart and patient. Observing the difference from the standard frequency pattern, the algorithm detects failure conditions. Therefore, this algorithm does not need prior knowledge of vibration characteristics corresponding to failures. After confirming that the vibration signal are affected by pump speed and pulsation in two kinds of mock circulatory loops, we performed thrombogenesis detection by using the failure detection system in mock circulatory loop with sheep blood. As a result, this system indicated a possibility of detecting the initial sign of thrombogenesis earlier than current signal. In conclusion, we think that this failure detection system can cooperate with other sensor systems of the SAH and enhance the ability of failure detection for the SAH.
Yamagishi, Hiromasa; Sankai, Yoshiyuki; Yamane, Takashi; Jikuya, Tomoaki; Tsutsui, Tatsuo
It is very important to grasp the artificial heart condition and the physiologic conditions for the implantable artificial heart. In our laboratory, a smart artificial heart (SAH) has been proposed and developed. An SAH is an artificial heart with a noninvasive sensor; it is a sensorized and intelligent artificial heart for safe and effective treatment. In this study, the following sensor systems for SAH are described: noninvasive blood temperature sensor system, noninvasive blood pressure sensor system, and noninvasive small blood flow sensor system. These noninvasive sensor systems are integrated and included around the artificial heart to evaluate these sensor systems for SAH by the mockup experiments and the animal experiments. The blood temperature could be measured stably by the temperature sensor system. Aortic pressure was estimated, and sucking condition was detected by the pressure sensor system. The blood flow was measured by the flow meter system within 10% error. As a result of these experiments, we confirmed the effectiveness of the sensor systems for SAH.
Kim, Dong Hyun; Kang, Seong-Woong; Park, Yoon Ghil; Lee, Hye Ree
Purpose For patients with neuromuscular disease, air stacking, which inflates the lungs to deep volumes, is important for many reasons. However, neuromuscular patients with severe glottic dysfunction or indwelling tracheostomy tubes cannot air stack effectively. For these patients, we developed a device that permits deep lung insufflations substituting for glottic function. Materials and Methods Thirty-seven patients with bulbar-innervated muscle weakness and/or tracheostomies were recruited. Twenty-three had amyotrophic lateral sclerosis, and 14 were tetraplegic patients due to cervical spinal cord injury. An artificial external glottic device (AEGD) was used to permit passive deep lung insufflation. In order to confirm the utility of AEGD, vital capacity, maximum insufflation capacity (MIC), and lung insufflation capacity (LIC) with AEGD (LICA) were measured. Results For 30 patients, MICs were initially zero. However, with the use of the AEGD, LICA was measurable for all patients. The mean LICA was 1,622.7±526.8 mL. Although MIC was measurable for the remaining 7 patients without utilizing the AEGD, it was significantly less than LICA, which was 1,084.3±259.9 mL and 1,862.9±248 mL, respectively (p<0.05). Conclusion The AEGD permits lung insufflation by providing deeper lung volumes than possible by air stacking. PMID:22028162
Dudkowska, A.; Makowiec, D.
In order to determine differences between healthy patients and patients with congestive heart failure we apply the artificial insymmetrised pattern (AIP) method. The AIP method by exploring a human eye ability to extract regularities and read symmetries in a dot pattern, serves a tool for qualitative discrimination of heart rate states.
Billeci, Lucia; Guerriero, Lorenzo; L'Abbate, Antonio; Pioggia, Giovanni; Tartarisco, Gennaro; Trivella, Maria Giovanna
Telemedicine has the potential to constitute the central element of the future primary care and become an effective means of prevention and early warning of acute exacerbation of chronic diseases. Up to now, the application of telemedicine has found a variety of difficulties, regarding the types and methods of acquisition and transmission of biological signals, the acceptance and cooperation of the patient, etc. The latest technological developments involve the combined use of wireless technologies and smartphones, for the collection and the transmission of data, and specific softwares for their automatic analysis. This paper examines some of the critical aspects in the application of new technologies for heart failure remote management.
Shiga, Takuya; Shiraishi, Yasuyuki; Sano, Kyosuke; Taira, Yasunori; Tsuboko, Yusuke; Yamada, Akihiro; Miura, Hidekazu; Katahira, Shintaro; Akiyama, Masatoshi; Saiki, Yoshikatsu; Yambe, Tomoyuki
Implantation of a total artificial heart (TAH) is one of the therapeutic options for the treatment of patients with end-stage biventricular heart failure. There is no report on the hemodynamics of the functional centrifugal-flow TAH with functional atrial contraction (fCFTAH). We evaluated the effects of pulsatile flow by atrial contraction in acute animal models. The goats received fCFTAH that we created from two centrifugal-flow ventricular assist devices. Some hemodynamic parameters maintained acceptable levels: heart rate 115.5 ± 26.3 bpm, aortic pressure 83.5 ± 10.1 mmHg, left atrial pressure 18.0 ± 5.9 mmHg, pulmonary pressure 28.5 ± 9.7 mmHg, right atrial pressure 13.6 ± 5.2 mmHg, pump flow 4.0 ± 1.1 L/min (left) 3.9 ± 1.1 L/min (right), and cardiac index 2.13 ± 0.14 L/min/m(2). fCFTAH with atrial contraction was able to maintain the TAH circulation by forming a pulsatile flow in acute animal experiments. Taking the left and right flow rate balance using the low internal pressure loss of the VAD pumps may be easier than by other pumps having considerable internal pressure loss. We showed that the remnant atrial contraction effected the flow rate change of the centrifugal pump, and the atrial contraction waves reflected the heart rate. These results indicate that remnant atria had the possibility to preserve autonomic function in fCFTAH. We may control fCFTAH by reflecting the autonomic function, which is estimated with the flow rate change of the centrifugal pump.
Lockard, Kathleen L; Allen, Carrie; Lohmann, Douglas; Severyn, Donald A; Schaub, Richard D; Kauffman, Kelly E; Hodges, Jeffrey R; Woodhall, Lorna; Ramanathan, Ramesh; Teuteberg, Jeffrey J; Eckert, Chad E; Kormos, Robert L
A patient with a HeartMate II left ventricular assist device who had a body mass index of 52 needed gastric bypass surgery in order to qualify for a heart transplant. Unlike previous experience in which the surgery was performed at the implant hospital, the gastric bypass surgery in this case was performed at a bariatric center of excellence that was a separate facility from the implant hospital. The artificial heart program of the University of Pittsburgh Medical Center worked with the bariatric center of excellence in scheduling the gastric bypass surgery using a multidisciplinary team approach at 2 hospitals to coordinate safe, high-quality patient care in a unique situation.
Kawabori, Masashi; Kurihara, Chitaru; Miller, Yair; Heck, Kent A; Bogaev, Roberta C; Civitello, Andrew B; Cohn, William E; Frazier, O H; Morgan, Jeffrey A
Idiopathic hypereosinophilic syndrome is a condition of unknown etiology characterized by proliferation of eosinophils and their infiltration into tissues. Although cardiac involvement is rare, eosinophilic myocarditis can lead to life-threating fulminant congestive heart failure. Treatment of patients with eosinophilic myocarditis is challenging as heart failure can be caused by biventricular dysfunction. To our knowledge, this is the first case reported in the literature describing a patient with acute severe biventricular heart failure caused by eosinophilic myocarditis with mural left ventricular apical thrombus who was successfully treated with implantation of a total artificial heart as a bridge to heart transplant.
Spiliopoulos, Sotirios; Koerfer, Reiner; Tenderich, Gero
The SynCardia total artificial heart is currently used as a bridge to transplantation therapy in cases of irreversible, acute or chronic, biventricular heart failure. We describe the implementation of this technology in the context of destination therapy in a patient with an end-stage heart failure on grounds of primary amyloidosis. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
Chu, Michael W A; Sharma, Kapil; Tchervenkov, Christo I; Jutras, Luc F; Lavoie, Josée; Shemie, Sam D; Laliberte, Eric; Calaritis, Christos; Cecere, Renzo
We report the implantation of a Berlin Heart ventricular assist device (VAD) in a 4-year-old boy with hypoplastic left heart syndrome previously palliated with Norwood and Glenn operations, who presented with progressive ventricular failure and hypoxemia. Insertion of a 30-mL pneumatic pediatric pump with cannulation of the systemic right ventricle and aorta had a salutary effect on cardiac output, improving oxygen saturations. While awaiting heart transplantation, multiple thromboembolic complications developed and he died, despite therapeutic heparinization and aspirin therapy. Important lessons learned about VAD support in Glenn physiology, anticoagulation, and complications of the Berlin Heart are discussed.
Hogan, Matthew; Mohamed, Mohamed; Tao, Ze-Wei; Gutierrez, Laura; Birla, Ravi
Only 3000 heart transplants are performed in the USA every year, leaving some 30 000-70 000 Americans without proper care. Current treatment modalities for heart failure have saved many lives yet still do not correct the underlying problems of congestive heart failure. Tissue engineering represents a potential field of study wherein a combination of cells, scaffolds, and/or bioreactors can be utilized to create constructs to mimic, replace, and/or repair defective tissue. The focus of this study was to generate a bioartificial heart (BAH) model using artificial heart muscle (AHM), composed of fibrin gel and neonatal rat cardiac myocytes, and a decellularized scaffold, formed by subjecting an adult rat heart to a series of decellularization solutions. By suturing the AHM around the outside of the decellularized heart and culturing while suspended in media, we were able to retain functional cardiac cells on the scaffold as evinced by visible contractility. Observed contractility rate was correlated with biopotential measurements to confirm essential functionality of cardiac constructs. Cross-sections of the BAH show successful decellularization of the scaffold and contiguous cell-rich AHM around the perimeter of the heart. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Rintoul, T C; Butler, K C; Thomas, D C; Carriker, J W; Maher, T R; Kiraly, R J; Massiello, A; Himley, S C; Chen, J F; Fukamachi, K
A completely implanted total artificial heart (TAH) is under development by Nimbus, Inc., and the Cleveland Clinic Foundation (CCF). Key features of the system include an electrohydraulic energy converter, an automatic control system that produces a Frank-Starling response, and dual ventricles composed of graphite-epoxy and titanium with gelatin blood contacting surfaces. The system is controlled by a single substrate, hybridized microcircuit (the hybrid). Fabrication of the TAH control hybrid has recently been completed and testing begun. Its design emphasizes simplicity, reliability, and efficiency. Particular attention was given to optimizing thermal management. Externally controlled TAH systems have been used in eight in vivo experiments of up to 120 days' duration. In the last two of these experiments, a variable volume device was also implanted with excellent results. In vivo use of the system has demonstrated the Frank-Starling pump response, but the systems quickly reach maximum output with the bovine animal models. Human fitting studies, including adult patients undergoing heart transplantation, demonstrated satisfactory fit of the pump within the pericardium without compression of the vascular structures or chest wall. Measurements of chest circumference, plain chest films, and transesophageal echocardiograms should provide reliable predictions of pump fit in the majority of patients.
Karimov, Jamshid H.; Steffen, Robert J.; Byram, Nicole; Sunagawa, Gengo; Horvath, David; Cruz, Vincent; Golding, Leonard A.R.; Fukamachi, Kiyotaka; Moazami, Nader
Implantation of mechanical circulatory support devices is challenging, especially in patients with a small chest cavity. We evaluated how well the Cleveland Clinic continuous-flow total artificial heart (CFTAH) fit the anatomy of patients about to receive a heart transplant. A mock pump model of the CFTAH was rapid-prototyped using biocompatible materials. The model was brought to the operative table, and the direction, length, and angulation of the inflow/outflow ports and outflow conduits were evaluated after the recipient's ventricles had been resected. Thoracic cavity measurements were based on preoperative computed tomographic data. The CFTAH fit well in all five patients (height, 170 ± 9 cm; weight, 75 ± 24 kg). Body surface area was 1.9 ± 0.3 m2 (range, 1.6-2.1 m2). The required inflow and outflow port orientation of both the left and right housings appeared consistent with the current version of the CFTAH implanted in calves. The left outflow conduit remained straight, but the right outflow direction necessitated a 73 ± 22 degree angulation to prevent potential kinking when crossing over the connected left outflow. These data support the fact that our design achieves the proper anatomical relationship of the CFTAH to a patient's native vessels. PMID:25806613
Rivard, Andrew L.
Abstract: The Asporto Heart Preservation Device is a system providing perfusion of cardioplegia to the donor heart using a computer-controlled peristaltic pump in a thermoelectrically cooled and insulated container. In 1998, a user interface was developed at the University of Minnesota consisting of a touch screen and battery-backed microcontroller. Power was supplied by a 120 VAC to 12 VDC converter. An upgrade to the insulated cooler and microcontroller occurred in 2002, which was followed by proof of concept experimental pre-clinical transplants and tests demonstrating the efficacy of the device with isolated donor hearts. During the period between 2002 and 2006, a variety of donor organ containers were developed, modified, and tested to provide an optimal sterile environment and fluid path. Parallel development paths encompass formalized design specifications for final prototypes of the touch screen/microcontroller, organ container, and thermoelectric cooler. PMID:26405361
Rivard, Andrew L
The Asporto Heart Preservation Device is a system providing perfusion of cardioplegia to the donor heart using a computer-controlled peristaltic pump in a thermoelectrically cooled and insulated container. In 1998, a user interface was developed at the University of Minnesota consisting of a touch screen and battery-backed microcontroller. Power was supplied by a 120 VAC to 12 VDC converter. An upgrade to the insulated cooler and microcontroller occurred in 2002, which was followed by proof of concept experimental pre-clinical transplants and tests demonstrating the efficacy of the device with isolated donor hearts. During the period between 2002 and 2006, a variety of donor organ containers were developed, modified, and tested to provide an optimal sterile environment and fluid path. Parallel development paths encompass formalized design specifications for final prototypes of the touch screen/microcontroller, organ container, and thermoelectric cooler.
Kremer, Jamila; Farag, Mina; Arif, Rawa; Brcic, Andreas; Sabashnikov, Anton; Schmack, Bastian; Popov, Aron-Frederik; Karck, Matthias; Dohmen, Pascal M.; Ruhparwar, Arjang; Weymann, Alexander
Background Total artificial heart (TAH) implantation in patients with aggressive tumor infiltration of the heart can be challenging. Case Report We report on a patient with a rare primary undifferentiated high-grade spindle cell sarcoma of the mitral valve and in the left atrium, first diagnosed in 2014. The referring center did a first resection in 2014. In the course of 17 months, computer tomography (CT) scan again showed massive invasion of the mitral valve and left atrium. Partial resection and mitral valve replacement was not an option. We did a subtotal heart excision with total artificial heart implantation. In this report we discuss complications, risk factors, and perioperative management of this patient. Conclusions Patients with aggressive tumors of the heart can be considered for TAH implantation. PMID:27803495
Kremer, Jamila; Farag, Mina; Arif, Rawa; Brcic, Andreas; Sabashnikov, Anton; Schmack, Bastian; Popov, Aron-Frederik; Karck, Matthias; Dohmen, Pascal M; Ruhparwar, Arjang; Weymann, Alexander
BACKGROUND Total artificial heart (TAH) implantation in patients with aggressive tumor infiltration of the heart can be challenging. CASE REPORT We report on a patient with a rare primary undifferentiated high-grade spindle cell sarcoma of the mitral valve and in the left atrium, first diagnosed in 2014. The referring center did a first resection in 2014. In the course of 17 months, computer tomography (CT) scan again showed massive invasion of the mitral valve and left atrium. Partial resection and mitral valve replacement was not an option. We did a subtotal heart excision with total artificial heart implantation. In this report we discuss complications, risk factors, and perioperative management of this patient. CONCLUSIONS Patients with aggressive tumors of the heart can be considered for TAH implantation.
Bruce, Courtenay R; Allen, Nathan G; Fahy, Bridget N; Gordon, Harvey L; Suarez, Erik E; Bruckner, Brian A
The use of mechanical circulatory support (MCS) devices has increased sixfold since 2006. Although there is an established legal and ethical consensus that patients have the right to withdraw and withhold life-sustaining interventions when burdens exceed benefits, this consensus arose prior to the widespread use of MCS technology and is not uniformly accepted in these cases. There are unique ethical and clinical considerations regarding MCS deactivation. Our center recently encountered the challenge of an awake and functionally improving patient with a total artificial heart (TAH) who requested its deactivation. We present a narrative description of this case with discussion of the following questions: (1) Is it ethically permissible to deactivate this particular device, the TAH? (2) Are there any particular factors in this case that are ethical contraindications to proceeding with deactivation? (3) What are the specific processes necessary to ensure a compassionate and respectful deactivation? (4) What proactive practices could have been implemented to lessen the intensity of this case's challenges? We close with a list of recommendations for managing similar cases.
Młyńczak, Marcel; Pariaszewska, Katarzyna; Niewiadomski, Wiktor; Cybulski, Gerard
The purpose of this study was to describe the design of the electronic module for testing bioimpedance measuring devices, for example impedance cardiographs or impedance pneumographs. Artificial Patient was conceived as an electronic equivalent of the impedance of skin-electrode interface and the impedance between electrodes - measured one. Different approaches in imitating a resistance of skin and an impedance of electrode-skin connection were presented. The module was adapted for frequently applied tetrapolar electrode configuration. Therefore the design do not enclose the elements simulating impedance between skin and receiver electrodes due to negligible effect of this impedance on the current flow through the receiver. The Artificial Patient enables testing either application generators, or receiver parts, particularly the level of noise and distortions of the signal. Use of digitally controlled potentiometer allows simulating different tissue resistances changes such as constant values, very-low-frequency and low-frequency changes corresponding to those caused by breathing or heart activity. Also it allows distorting signals in order to test algorithms of artifacts attenuation.
Kiselev, Iu M; Mordashev, V M; Osipov, A P; Shumakov, V I
The authors review the thermodynamic bases and physiological limitations of the applicability of thermal engines for driving artificial heart ventricles. Show that the thermodynamic characteristics of Stirling and Brighton cycles do not make it possible to effectively use cycle-based engines in the artificial heart. A steam engine operating in accordance with the Rankine cycle may be regarded as an optimum type engine for that purpose. Demonstrate that according to the rules of physiology, use should be made of a separate driving of artificial heart ventricles by two independently operating steam engines. Provide the characteristics of the Soviet artificial heart "MIKRON" acceptable for implantation into the orthotopic position.
Ding, H; Chen, Z; Shen, L; Xu, M; Zhou, Y; Xu, S; Zeng, Y
The myocardial tissue covering the artery is termed a myocardial bridge. But so far many researches on the myocardial bridge have been involved with clinical patients or animals, which have some limitations (e.g. lack of systematicness, difficulties in measuring the flow in the mural coronary artery and so on). Designing a "Heart-Mural coronary artery-Myocardial Bridge" Simulative Device provides a good approach to solve above problems; however, documents on this subject have seldom been reported until now. The heart pump as the key part of the whole simulative device should be able to simulate the waveform of blood pressure, adjust blood flow and regulate heart rate. Our experimental results basically met above requirements. The heart pump proposed in the paper presented an alternative experimental method to go further into other issues about the cardiovascular circulation system.
Reich, H; Czer, L; Bannykh, S; De Robertis, M; Wolin, E; Amersi, F; Moriguchi, J; Kobashigawa, J; Arabia, F
Malignancy is the leading cause of long-term morbidity and mortality after heart and other solid organ transplantation; therefore, great emphasis is placed on pre- and post-transplantation cancer screening. Even with meticulous screening during evaluation for heart transplant candidacy, an occult cancer may not be apparent. Here, we share the case of a 51-year-old man with refractory heart failure who underwent total artificial heart implantation as a bridge to transplantation with the surprise finding of an isolated deposit of metastatic carcinoid tumor nested within a left ventricular papillary muscle in his explanted heart. The primary ileal carcinoid tumor was identified and resected completely. After remaining cancer-free for 14 months, he was listed for heart transplantation and was transplanted 2 months later. He is currently 3.5 months out from heart transplantation and doing well, without evidence of recurring malignancy. Copyright © 2015 Elsevier Inc. All rights reserved.
Ried, Michael; Rupprecht, Leopold; Hirt, Stephan; Zausig, York; Grube, Matthias; Resch, Markus; Hilker, Michael; Hofstädter, Ferdinand; Schmid, Christof
Primary cardiac T-cell lymphoma is an extremely rare entity, with only 3 patients having been reported so far in the literature. We describe the case of a young patient with acute heart failure involving the whole myocardium. The patient successfully underwent emergency cardiectomy, custom-made total artificial heart implantation and heart transplantation, combined with chemotherapy. The problems we encountered with this rare disease are discussed and compared with those of previous studies. Copyright 2010 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.
Scully, Michael S; Wessman, Dylan E; McKee, James M; Francisco, Gregory M; Nayak, Keshav R; Kobashigawa, Jon A
Cardiac involvement by light-chain (AL) amyloid occurs in up to 50% of patients with primary AL amyloidosis. The prognosis of amyloid heart disease is poor with 1-year survival rates of 35 to 40%. Historically, heart transplantation was considered controversial for patients with AL amyloid cardiomyopathy (CM) given the systemic nature of the disease and poor survival. We present a case report of an active duty service member diagnosed with advanced cardiac amyloid who underwent total artificial heart transplant as a bridge to heart transplant and eventual autologous stem cell transplant. A 47-year-old active duty male initially evaluated for atypical chest pain was found to have severe concentric left ventricular hypertrophy on echocardiogram but normal voltage on electrocardiogram. Cardiac magnetic resonance imaging, laboratory studies, and bone marrow biopsy established the diagnosis of cardiac amyloidosis. At the time of diagnosis, the patient's prognosis was very poor with a median survival of 5 months on the basis of the Mayo Clinic revised prognostic staging system for amyloidosis. The patient developed rapidly progressive left ventricular dysfunction and heart failure leading to cardiac arrest. The patient received a total artificial heart as a bridge to orthotopic heart and kidney transplantation and eventual stem cell transplant. He continues to be in remission and has a fair functional capacity without restriction in activities of daily living or moderate exercise. Amyloid CM is a rare and devastating disease. The natural course of the disease has made heart transplant in these patients controversial. Modern advancements in chemotherapies and advanced heart failure treatments have improved outcomes for select patients with AL amyloid CM undergoing heart transplantation. There is ongoing research seeking improvement in treatment options and outcomes for patients with this deadly disease. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.
Borders, William A.; Akima, Hisanao; Fukami, Shunsuke; Moriya, Satoshi; Kurihara, Shouta; Horio, Yoshihiko; Sato, Shigeo; Ohno, Hideo
We demonstrate associative memory operations reminiscent of the brain using nonvolatile spintronics devices. Antiferromagnet-ferromagnet bilayer-based Hall devices, which show analogue-like spin-orbit torque switching under zero magnetic fields and behave as artificial synapses, are used. An artificial neural network is used to associate memorized patterns from their noisy versions. We develop a network consisting of a field-programmable gate array and 36 spin-orbit torque devices. An effect of learning on associative memory operations is successfully confirmed for several 3 × 3-block patterns. A discussion on the present approach for realizing spintronics-based artificial intelligence is given.
Black, Matthew C; Schumer, Erin M; Rogers, Michael; Trivedi, Jaimin; Slaughter, Mark S
Advanced heart failure (HF) patients not meeting criteria for ventricular assist device or heart transplant with life-limiting symptoms are limited to medical and resynchronization therapy. The Sunshine Heart C-Pulse, based on intra-aortic balloon pump physiology, provides implantable, on-demand, extra-aortic counterpulsation, which reduces afterload and improves cardiac perfusion in New York Heart Association Class III and ambulatory Class IV HF. The C-Pulse reduces New York Heart Association Class, improves 6-min walk distances, inotrope requirements and HF symptom questionnaires. Advantages include shorter operative times without cardiopulmonary bypass, no reported strokes or thrombosis and no need for anticoagulation. Driveline exit site infections, inability to provide full circulatory support and poor function with intractable arrhythmias remain concerns. Current randomized controlled studies will evaluate long-term efficacy and safety compared with medical and resynchronization therapy.
Miller, Jacob R; Eghtesady, Pirooz
Despite advances in medical and surgical therapies, some children with congenital heart disease (CHD) are not able to be adequately treated or palliated, leading them to develop progressive heart failure. As these patients progress to end-stage heart failure they pose a unique set of challenges. Heart transplant remains the standard of care; the donor pool, however, remains limited. Following the experience from the adult realm, the pediatric ventricular assist device (VAD) has emerged as a valid treatment option as a bridge to transplant. Due to the infrequent necessity and the uniqueness of each case, the pediatric VAD in the CHD population remains a topic with limited information. Given the experience in the adult realm, we were tasked with reviewing pediatric VADs and their use in patients with CHD and comparing this therapy to heart transplantation when possible. PMID:25350804
Chowdhury, Anindita; Mathew, Reeba; Castriotta, Richard J
Chronic heart failure (CHF) represents a major health and economic burden and is associated with high rates of hospital admission, morbidity, mortality and decreased quality-adjusted life years. New advances in the treatment of CHF such as ventricular assist devices (VADs) and heart transplantation have helped improve outcomes. Sleep-disordered breathing (SDB) is highly prevalent in CHF patients and the associated morbidity makes it essential for physicians to be more cognizant about its existence, interaction and need for treatment. This is a review of what is known to date about SDB in CHF patients who have undergone advanced treatments with VADs and/or heart transplantation.
Gräf, Felix; Finocchiaro, Thomas; Laumen, Marco; Mager, Ilona; Steinseifer, Ulrich
Hemocompatibility of blood pumps is a crucial parameter that has to be ensured prior to in vivo testing. In contrast to rotary blood pumps, a standard for testing a pulsatile total artificial heart (TAH) has not yet been established. Therefore, a new mock circulation loop was designed to investigate hemolysis in the left ventricle of the ReinHeart TAH. Its main features are a high hemocompatibility, physiological conditions, a low priming volume, and the conduction of blood through a closed tubing system. The mock circulation loop consists of a noninvasive pressure chamber, an aortic compliance chamber, and an atrium directly connected to the ventricle. As a control pump, the clinically approved Medos-HIA ventricular assist device (VAD) was used. The pumps were operated at 120 beats per minute with an aortic pressure of 120 to 80 mm Hg and a mean atrial pressure of 10 mm Hg, generating an output flow of about 5 L/min. Heparinized porcine blood was used. A series of six identical tests were performed. A test method was established that is comparable to ASTM F 1841, which is standard practice for the assessment of hemolysis in continuous-flow blood pumps. The average normalized index of hemolysis (NIH) values of the VAD and the ReinHeart TAH were 0.018 g/100 L and 0.03 g/100 L, respectively. The standard deviation of the NIH was 0.0033 for the VAD and 0.0034 for the TAH. Furthermore, a single test with a BPX-80 Bio-Pump was performed to verify that the hemolysis induced by the mock circulation loop was negligible. The performed tests showed a good reproducibility and statistical significance. The mock circulation loop and test protocol developed in this study are valid methods to investigate the hemolysis induced by a pulsatile blood pump. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Shen, Mark J; Zipes, Douglas P
"Heart failure is an increasingly prevalent disease with high mortality and public health burden. It is associated with autonomic imbalance characterized by sympathetic hyperactivity and parasympathetic hypoactivity. Evolving novel interventional and device-based therapies have sought to restore autonomic balance by neuromodulation. Results of preclinical animal studies and early clinical trials have demonstrated the safety and efficacy of these therapies in heart failure. This article discusses specific neuromodulatory treatment modalities individually-spinal cord stimulation, vagus nerve stimulation, baroreceptor activation therapy, and renal sympathetic nerve denervation."
Atienza, F.; Martinez-Alzamora, N.; De Velasco, J. A.; Dreiseitl, S.; Ohno-Machado, L.
Accurate risk stratification of heart failure patients is critical to improve management and outcomes. Heart failure is a complex multisystem disease in which several predictors are categorical. Neural network models have successfully been applied to several medical classification problems. Using a simple neural network, we assessed one-year prognosis in 132 patients, consecutively admitted with heart failure, by classifying them in 3 groups: death, readmission and one-year event-free survival. Given the small number of cases, the neural network model was trained using a resampling method. We identified relevant predictors using the Automatic Relevance Determination (ARD) method, and estimated their mean effect on the 3 different outcomes. Only 9 individuals were misclassified. Neural networks have the potential to be a useful tool for making prognosis in the domain of heart failure. PMID:11079839
Vanderheyden, Marc; Bartunek, Jozef
While heart failure is one of the leading causes of mortality and morbidity, our tools to provide ultimate treatment solutions are still limited. Recent developments in new devices are designed to fill this therapeutic gap. The scope of this review is to focus on two particular targets, namely (1) left ventricular geometric restoration and (2) atrial depressurization. (1) Reduction of the wall stress by shrinking the ventricular cavity has been traditionally attempted surgically. Recently, the Parachute device (CardioKinetix Inc., Menlo Park, CA, USA) has been introduced to restore ventricular geometry and cardiac mechanics. The intervention aims to partition distal dysfunctional segments that are non-contributory to the ventricular mechanics and forward cardiac output. (2) Diastolic heart failure is characterized by abnormal relaxation and chamber stiffness. The main therapeutic goal achieved should be the reduction of afterload and diastolic pressure load. Recently, new catheter-based approaches were proposed to reduce left atrial pressure and ventricular decompression: the InterAtrial Shunt Device (IASD™) (Corvia Medical Inc., Tewksbury, MA, USA) and the V-Wave Shunt (V-Wave Ltd, Or Akiva, Israel). Both are designed to create a controlled atrial septal defect in symptomatic patients with heart failure. While the assist devices are aimed at end-stage heart failure, emerging device-based percutaneous or minimal invasive techniques comprise a wide spectrum of innovative concepts that target ventricular remodeling, cardiac contractility or neuro-humoral modulation. The clinical adoption is in the early stages of the initial feasibility and safety studies, and clinical evidence needs to be gathered in appropriately designed clinical trials. PMID:26966444
... heart rhythm when the heart beats too slowly. Implantable cardioverter defibrillators : These deliver a shock to restore ... become blocked again. Ventricular assist devices : These mechanical pumps help weak hearts pump blood effectively. While originally ...
Hecht, J; Körner, E
The possibility of controlling an artificial heart by the arteriovenous oxygen difference is discussed by means of the model simulation of the human organism. The simulation results are compared with these of the control by the Starling mechanism. No improvement of the results was obtainable because the behaviour of the arteriovenous oxygen difference is very dependent on the kind and the ascent of the load. The control of the artificial heart by the Starling mechanism appeared more favourable also on changed conditions in the atrium.
Richard N. Conner; James G. Dickson; J. Howard Williamson
We suggest that the fungus Spongipellis pachyodon might be used to artificially create suitable hardwood nest trees for woodpeckers in both young and older trees and when supplies of potential nest trees are limited. Sizes of trees suitable for inoculation, inoculation heights, and densities of snags are suggested for six species of woodpeckers.
Bakanovskaya, L. N.
The article touches upon building of a heart electrical axis position conclusion model using an artificial neural network. The input signals of the neural network are the values of deflections Q, R and S; and the output signal is the value of the heart electrical axis position. Training of the network is carried out by the error propagation method. The test results allow concluding that the created neural network makes a conclusion with a high degree of accuracy.
Advanced heart failure is a heterogeneous condition unified by a very high mortality unless right treatment is instituted at the right time. The first step is understanding the mechanism leading to instability: hemodynamic or ischemic. Right kind of therapy; drugs (ionotropic) or IABP or other cardiac assist devices should be chosen according to mechanism of insult as well as degree of insult. Drugs such as ionotropes are effective only in very early course but if the decompensation has progressed beyond a certain point device such as IABP may be effective but again only early in the course when CPO? 0.6. Beyond a certain point, even IABP may not be effective: here only Impella (2.5, CP or 5) or Tandem Heart may be effective. However, beyond a certain point CPO<0.53, even these devices may not be effective. Thus crux of the matter is choice of a right device/drug and timing of its institution.
Samara, Michael A; Tang, W H Wilson
Acute heart failure syndromes (AHFS) represent the most common discharge diagnoses in adults over age 65 and translate into dramatically increased heart failure-associated morbidity and mortality. Conventional approaches to the early detection of pulmonary and systemic congestion have been shown to be of limited sensitivity. Despite their proven efficacy, disease management and structured telephone support programs have failed to achieve widespread use in part due to their resource intensiveness and reliance upon motivated patients. While once thought to hold great promise, results from recent prospective studies on telemonitoring strategies have proven disappointing. Implantable devices with their capacity to monitor electrophysiologic and hemodynamic parameters over long periods of time and with minimal reliance on patient participation may provide solutions to some of these problems. Conventional electrophysiologic parameters and intrathoracic impedance data are currently available in the growing population of heart failure patients with equipped devices. A variety of implantable hemodynamic monitors are currently under investigation. How best to integrate these devices into a systematic approach to the management of patients before, during, and after AHFS is yet to be established.
Lee, Hwansung; Tsukiya, Tomonori; Homma, Akihiko; Kamimura, Tadayuki; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Kitamura, Soichiro
It has been conceived that the mechanical heart valves mounted in an artificial heart close much faster than in vivo use, resulting in cavitation bubbles formation. In this study, the mechanisms for cavitation in mechanical heart valves (MHVs) is investigated with monoleaflet and bileaflet valves in the mitral position with an electrohydraulic total artificial heart (EHTAH). The valve-closing velocity and pressure-drop through the valve were done, and a high-speed video camera was employed to investigate the mechanism for MHVs cavitation. The valve-closing velocity and pressure-drop of the bileaflet valves were less than that of the monoleaflet valves. Most of the cavitation bubbles in the monoleaflet valves were observed next to the edge of the valve stop and the inner side of the leaflet. With the bileaflet valves, cavitation bubbles were concentrated along the leaflet tip. Also, the number density of cavitation bubbles in the bileaflet valves was less than that of the monoleaflet valves. The number density of cavitation bubbles increased with an increase in the valve-closing velocity and the valve stop area. It is established that squeeze flow holds the key to cavitation in the mechanical heart valve. In a viewpoint of squeeze flow, the bileaflet valve with slow valve-closing velocity and small valve stop area, is safer to prevent of blood cell damage than the monoleaflet valves.
Kamohara, Keiji; Weber, Stephan; Klatte, Ryan S; Ootaki, Yoshio; Akiyama, Masatoshi; Kopcak, Michael W; Luangphakdy, Viviane; Flick, Christine R; Chen, Ji-Feng; Navia, Jose L; Smith, William A; Fukamachi, Kiyotaka
The MagScrew total artificial heart (TAH) is under development. Despite its anticipated durability and reliability, the possibility of a bioprosthetic valve malfunction exists. As a result, the potential for valve replacement surgery, instead of device replacement, would be desirable after a TAH implant. In two of our 90-day animal experiments, we successfully replaced the left-side valves through a left thoracotomy opposite to the right-sided incision site for the initial TAH implant. The results of these cases suggest that the left-side valves could also be replaced through a left thoracotomy approach in humans. To confirm the ability to access the left-side valves in humans, four human cadaver studies were performed with the use of a mock pump designed for human application. This report describes the operative techniques for left-side valve replacement in animals and discusses the advantages of a left thoracotomy in clinical situations, based on results from the human cadaver studies.
Okamoto, E; Inoue, T; Watanabe, K; Hashimoto, T; Iwazawa, E; Abe, Y; Chinzei, T; Isoyama, T; Kobayashi, S; Saito, I; Sato, F; Matsuki, H; Imachi, K; Mitamura, Y
The purpose of this study was to demonstrate the feasibility of the use of an implantable, high-energy, and compact battery system for an undulation pump total artificial heart (UPTAH). The implantable battery system tested consists of six lithium-ion batteries in series, a charge unit, and a charge/discharge control unit. A lithium-ion battery is currently the best energy-storage device because it has more energy density, a better life cycle, and a smaller temperature rise than those of other secondary batteries. The performance of the implantable battery system was evaluated in an in vitro experiment using an electric load that simulated the UPTAH. Also, sufficiently reliable operation of a system for supplying energy to a UPTAH consisting of a transcutaneous energy transmission system (TETS) and an implantable battery system was confirmed in three experiments using goats. The results of the in vitro and in vivo experiments showed that the implantable battery system supplied sufficient current to the UPTAH for maintenance of physiological conditions in the goat with maximum rise in temperature to less than 43 degrees C.
Pavie, A; Leger, P; Regan, M; Nataf, P; Bors, V; Szefner, J; Cabrol, C; Gandjbakhch, I
Since April 1986, 82 patients have received a pneumatic total artificial heart, 62 a JARVIK-7, and 20 a Cardiowest. The duration of support ranged from less than 1 day to 603 days (mean duration: 27 +/- 82). The indications were for acute shock (38 cases) or for chronic deterioration on the transplant waiting list (44 cases). The etiology was mainly due to idiopathic and ischemic cardiomyopathy. With the help of our scoring system, we divided our patients in three groups: Chronic Implantation, represented by two females staying on device for 6 and 19 months, respectively; a High-Risk group of 29 patients characterized by high-risk indications; graft failure, rejection, postcardiotomy patient, postpartum cardiomyopathy, and valvular and congenital reoperation. In addition, the dilated and ischemic cardiomyopathy patients with a score over 6 were included in this group; and an Elective Indication group (51 patients) represented all of the dilated and ischemic cardiomyopathy patients with a score under 6. Due to the shortage of donors, our criteria for transplantation are very strict. Transplants should be made only in cases of hemodynamic stability, on an extubated patient with normal renal and liver functions, without coagulation problems or infection. With such criteria, in the high-risk group, only four patients could be transplanted and of these two are still alive. In contrast, in the elective group, 31 were transplanted (61%), and 71% of these patients were discharged. The rate is improved in the most recent cases, with 90% of the Cardiowest patients being survivors.
Kobayashi, Mariko; Horvath, David J.; Mielke, Nicole; Shiose, Akira; Kuban, Barry; Goodin, Mark; Fukamachi, Kiyotaka; Golding, Leonard A. R.
Cleveland Clinic’s continuous-flow total artificial heart has one motor and one rotating assembly supported by a hydrodynamic bearing. The right hydraulic output is self regulated by passive axial movement of the rotating assembly to balance itself with the left output. The purpose of this article is to present progress in four areas of development: the automatic speed control system, self-regulation to balance right/left inlet pressures and flows, hemolysis testing using calf blood, and coupled electromagnetics (EMAG) and computational fluid dynamics (CFD) analysis. The relationships between functions of motor power and speed, systemic flow, and systemic vascular resistance (SVR) were used for the sensorless speed control algorithm and demonstrated close correlations. Based on those empirical relationships, systemic flow and SVR were calculated in the system module and showed good correlation with measured pump flow and SVR. The automatic system adjusted the pump’s speed to obtain the target flow in response to the calculated SVR. Atrial pressure difference (left minus right atrial pressure) was maintained within ± 10 mm Hg for a wide range of SVR/PVR (systemic/pulmonary vascular resistance) ratios, demonstrating a wide margin of self-regulation under fixed-speed mode and 25% sinusoidally modulated speed mode. Hemolysis test results indicated acceptable values (normalized index of hemolysis <.01 mg/dL). The coupled EMAG/CFD model was validated for use in further device development. PMID:22747979
Ng, Boon C; Smith, Peter A; Nestler, Frank; Timms, Daniel; Cohn, William E; Lim, Einly
The successful clinical applicability of rotary left ventricular assist devices (LVADs) has led to research interest in devising a total artificial heart (TAH) using two rotary blood pumps (RBPs). The major challenge when using two separately controlled LVADs for TAH support is the difficulty in maintaining the balance between pulmonary and systemic blood flows. In this study, a starling-like controller (SLC) hybridized with an adaptive mechanism was developed for a dual rotary LVAD TAH. The incorporation of the adaptive mechanism was intended not only to minimize the risk of pulmonary congestion and atrial suction but also to match cardiac demand. A comparative assessment was performed between the proposed adaptive starling-like controller (A-SLC) and a conventional SLC as well as a constant speed controller. The performance of all controllers was evaluated by subjecting them to three simulated scenarios [rest, exercise, head up tilt (HUT)] using a mock circulation loop. The overall results showed that A-SLC was superior in matching pump flow to cardiac demand without causing hemodynamic instabilities. In contrast, improper flow regulation by the SLC resulted in pulmonary congestion during exercise. From resting supine to HUT, overpumping of the RBPs at fixed speed (FS) caused atrial suction, whereas implementation of SLC resulted in insufficient flow. The comparative study signified the potential of the proposed A-SLC for future TAH implementation particularly among outpatients, who are susceptible to variety of clinical scenarios.
Demondion, Pierre; Fournel, Ludovic; Niculescu, Michaela; Pavie, Alain; Leprince, Pascal
The total artificial heart (TAH) helps to counteract the current decrease in heart donors and is likely to bridge patients to transplant under favourable conditions. Today's mobile consoles facilitate home discharge. The aim of this study was to report on the La Pitie Hospital experience with CardioWest TAH recipients, and more particularly, on generally successful outpatient' management. A retrospective analysis was performed on clinical and biological data from patients implanted with a TAH between December 2006 and July 2010 in a single institution. Morbi-mortality during hospital stay, number and causes of rehospitalizations, quality of life during home discharge, bridge to transplant results and survival have all been analysed. Twenty-seven patients were implanted with the CardioWest. Fifteen patients (55.5%) died during support. Prior to home discharge, the most frequent cause of death was multi-organ failure (46.6%). Twelve patients were discharged home from hospital within a median of 88 days [range 35-152, interquartile range 57] postimplantation. Mean rehospitalization rate was 1.2 by patient, on account of device infection (n = 7), technical problems with the console (n = 3) and other causes (n = 4). Between discharge and transplant, patients spent 87% of their support time out of hospital. All patients who returned home with the TAH were subsequently transplanted, and 1 died in post-transplant. Despite the morbidity and mortality occurring during the postimplantation period, home discharge with a TAH is possible. Portables drivers allow for a safe return home. Aside from some remaining weak points such as infectious complications or noise, CardioWest TAH allows for successful rehabilitation of graft candidates, and assures highly satisfactory transplant results.
Shiga, Takuya; Kuroda, Takehito; Tsuboko, Yusuke; Miura, Hidekazu; Shiraishi, Yasuyuki; Yambe, Tomoyuki
Hemodynamic effects of atrial contraction with centrifugal pump type total artificial heart is unknown. In this study, we simulated an atrial contraction in a mock model. By the driving condition with higher pressure in the mock atrial model, the load during atrial contraction increased. Based on these findings, we examined atrial contraction in the animal using adult goats. Prior to the measurement, we installed a centrifugal-type ventricular assist device (VADs), and then clamped both ventricles. We measured the hemodynamic data without ventricular contractile functions in order to obtain the effect of atrial contraction on hemodynamics under the condition of the total artificial heart (TAH) circulatory support model. We could estimate the heart rate by revolution number and voltage of pumps. There might be a possibility that we could regulate autonomic nervous response with the control of cardiac output.
Carpentier, Benoît; Ash, Stephen R
Devices for support of patients with liver failure are of two types: bioartificial livers and artificial livers. Bioartificial livers include hepatocytes in bioreactors to provide both excretory and synthetic liver functions. Artificial livers use nonliving components to remove toxins of liver failure, supply nutrients and macromolecules. Current artificial liver devices use columns or suspensions of sorbents (including adsorbents and absorbents) to selectively remove toxins and regenerate dialysate, albumin-containing dialysate, plasma filtrate or plasma. This article reviews three artificial liver devices. Liver Dialysis uses a suspension of charcoal and cation exchangers to regenerate dialysate. MARS uses charcoal and an anion exchanger to regenerate dialysate with albumin. Prometheus uses neutral and anion exchange resins to regenerate a plasma filtrate containing albumin and small globulins. We review the operating principles, chemical effects, clinical effects and complications of use of each type of artificial liver. These devices clearly improve the clinical condition of patients with acute or acute-on-chronic liver failure. Further randomized outcome studies are necessary to prove clinical outcome benefit of the artificial liver support devices, and define what types of patients appear most amenable to therapy.
Chilaya, S M; Khodeli, N G
Left ventricular and biventricular bypasses (LVBs, BVBs) were performed in 102 experiments in sheep, goats, and donkeys. Biventricular bypass was performed in the assisted circulation mode or in the paracorporeal artificial heart bridge (PCAHB) mode when the natural heart fibrillates. During implantation of artificial ventricles instead of a heart-lung bypass, counterpulsation was used. Several types of connective conduits were developed and tested in experiments. The conduits included bifurcational connective pipes that permit "intake" of blood into artificial ventricles from atria and ventricles of the natural heart simultaneously and consequently provide effective blood flow through shunts not depending on the state of the natural heart (acute cardiac weakness or asystole). Monitoring gas content (PO2, PCO2, and pH) in the myocardium of both ventricles suggested development of right ventricular failure under conditions of LVB before hemodynamic changes occurred and confirmed the preferability of BVB over other methods of assisted circulation, as it is most effective and capable of normalizing short-term cardiac disturbances in the course of the 1st 2 days. Survival time of experimental animals (2-3 days for dogs, 5-12 days for sheep, goats, and donkeys) is sufficient to overcome acute cardiac insufficiency. This suggests that BVB in the assisted circulation mode or PCAHB mode can serve as a bridge for cardiac transplantation for the time of search for the available organ.
Raia, Federica; Deng, Mario C
In the US population of 300 million, 3 million have heart failure with reduced ejection fraction and 300,000 have advanced heart failure. Long-term mechanical circulatory support will, within the next decade, be recommended to 30,000 patients annually in the USA, 3000 undergo heart transplantation annually. What do these advances mean for persons suffering from advanced heart failure and their loved ones/caregivers? In this perspective article, we discuss - by exemplifying a case report of a 27-year-old man receiving a Total Artificial Heart - a practice concept of modern medicine that fully incorporates the patient's personhood perspective which we have termed Relational Medicine™. From this case study, it becomes apparent that the successful practice of modern cardiovascular medicine requires the person-person encounter as a core practice element.
Banerjee, Dipanjan; Dutt, Debleena; Duclos, Sebastien; Sallam, Karim; Wheeler, Matthew; Ha, Richard
Many clinicians caring for patients with continuous flow left ventricular assist devices (CF-LVAD) use ramp right heart catheterization (RHC) studies to optimize pump speed and also to troubleshoot CF-LVAD malfunction. An investigational device, the ReliantHeart Heart Assist 5 (Houston, TX), provides the added benefit of an ultrasonic flow probe on the outflow graft that directly measures flow through the CF-LVAD. We performed a simultaneous ramp RHC and echocardiogram on a patient who received the above CF-LVAD to optimize pump parameters and investigate elevated flow through the CF-LVAD as measured by the flow probe. We found that the patient's hemodynamics were optimized at their baseline pump speed, and that the measured cardiac output via the Fick principle was lower than that measured by the flow probe. Right heart catheterization may be useful to investigate discrepancies between flow measured by a CF-LVAD and a patient's clinical presentation, particularly in investigational devices where little clinical experience exists. More data is needed to elucidate the correlation between the flow measured by an ultrasonic probe and cardiac output as measured by RHC.
Banerjee, Dipanjan; Dutt, Debleena; Duclos, Sebastien; Sallam, Karim; Wheeler, Matthew; Ha, Richard
Many clinicians caring for patients with continuous flow left ventricular assist devices (CF-LVAD) use ramp right heart catheterization (RHC) studies to optimize pump speed and also to troubleshoot CF-LVAD malfunction. An investigational device, the ReliantHeart Heart Assist 5 (Houston, TX), provides the added benefit of an ultrasonic flow probe on the outflow graft that directly measures flow through the CF-LVAD. We performed a simultaneous ramp RHC and echocardiogram on a patient who received the above CF-LVAD to optimize pump parameters and investigate elevated flow through the CF-LVAD as measured by the flow probe. We found that the patient’s hemodynamics were optimized at their baseline pump speed, and that the measured cardiac output via the Fick principle was lower than that measured by the flow probe. Right heart catheterization may be useful to investigate discrepancies between flow measured by a CF-LVAD and a patient’s clinical presentation, particularly in investigational devices where little clinical experience exists. More data is needed to elucidate the correlation between the flow measured by an ultrasonic probe and cardiac output as measured by RHC. PMID:28163837
Wendel, H P; Ziemer, G
Extracorporeal circulation procedures have been shown to induce complement and leukocyte activation, release of endotoxin and inflammatory mediators, including cytokines, nitric oxide, oxygen free radicals, and platelet activating factors. The contact between the blood and the various artificial surfaces of the extracorporeal system results in an unspecific post-perfusion syndrome. For diminishing these negative side effects several coating-techniques have been developed to create devices with improved hemocompatibility. This review deals with the current knowledge of heparin-coated and otherwise surface-modified perfusion systems. The pathway how heparin-coated surfaces work is discussed and techniques for surface-coatings, both clinically introduced as well as newly developed are presented. Numerous clinical studies compared heparin-coated versus non-coated circuits. Heparin-bonded devices showed lessened humoral and cellular activation, in particular a reduced complement activation with a reduced inflammatory post-perfusion syndrome. Also platelet protection and more favorable post-operative lung function are of particular note. Recent clinical trials demonstrated shortened hospital stays, less drainage bleeding, and reduced cerebral complications using heparin-coated oxygenation systems. The diminished expression of the leukocyte adhesion molecules CD 11b/c in CBAS devices points to a decreased activation of neutrophils. In addition, one research group found a reduced production of oxygen radicals. Heparin-bonding minimizes oxygenator failure by a significant reduced pressure gradient across the oxygenator, probably caused by decreased fibrin and platelet deposition at the hollow fiber surfaces. A meta analysis examined the impact of heparin-bonded systems on clinical outcomes and resulting costs. Using heparin-bonded circuits led to total cost savings from US $1000 to 3000. Several authors demonstrated reduced blood loss and better clinical outcome by
Karimov, Jamshid H; Gao, Shengqiang; Dessoffy, Raymond; Sunagawa, Gengo; Sinkewich, Martin; Grady, Patrick; Sale, Shiva; Moazami, Nader; Fukamachi, Kiyotaka
Successful implantation of a total artificial heart relies on multiple standardized procedures, primarily the resection of the native heart, and exacting preparation of the atrial and vascular conduits for pump implant and activation. Achieving secure pump connections to inflow/outflow conduits is critical to a successful outcome. During the connection process, however, air may be introduced into the circulation, traveling to the brain and multiple organs. Such air emboli block blood flow to these areas and are detrimental to long-term survival. A correctly managed pump-to-conduit connection prevents air from collecting in the pump and conduits. To further optimize pump-connection techniques, we have developed a novel connecting sleeve that enables airless connection of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) to the conduits. In this brief report, we describe the connecting sleeve design and our initial results from two acute in vivo implantations using a scaled-down version of the CFTAH.
Hoganson, David M; Boston, Umar S; Gazit, Avihu Z; Canter, Charles E; Eghtesady, Pirooz
In patients with failed Fontan circulation, end-stage heart failure can develop or Fontan physiology failure requiring transplantation. Experience with ventricular assist device support for these patients as a bridge to heart transplantation has been limited and often not resulted in successful hospital discharge. We report the successful use of the Berlin Heart EXCOR (Berlin Heart, The Woodlands, TX) ventricular assist device in bridging a child with Fontan circulation and systolic dysfunction to heart transplantation and discharge home.
O'Brien, Benjamin M.; Rosset, Samuel; Shea, Herbert R.; Anderson, Iain A.
Artificial muscles based on dielectric elastomers show enormous promise for a wide range of applications and are slowly moving from the lab to industry. One problem for industrial uptake is the expensive, rigid, heavy and bulky high voltage driver, sensor and control circuitry that artificial muscle devices currently require. One recent development, the Dielectric Elastomer Switch(es) (DES), shows promise for substantially reducing auxiliary circuitry and helping to mature the technology. DES are piezoresistive elements that can be used to form logic, driver, and sensor circuitry. One particularly useful feature of DES is their ability to embed oscillatory behaviour directly into an artificial muscle device. In this paper we will focus on how DES oscillators can break down the barriers to industrial adoption for artificial muscle devices. We have developed an improved artificial muscle ring oscillator and applied it to form a mechanosensitive conveyor. The free running oscillator ran at 4.4 Hz for 1056 cycles before failing due to electrode degradation. With better materials artificial muscle oscillators could open the door to robots with increased power to weight ratios, simple-to-control peristaltic pumps, and commercially viable artificial muscle motors.
Crosby, Jessica R.; DeCook, Katrina J.; Tran, Phat L.; Smith, Richard G.; Larson, Douglas F.; Khalpey, Zain I.; Burkhoff, Daniel; Slepian, Marvin J.
The SynCardia total artificial heart (TAH) has emerged as an effective, life-saving bi-ventricular replacement system for a wide variety of patients with end-stage heart failure. While the clinical performance of the TAH is established, modern physiologic characterization, in terms of elastance behavior and pressure-volume characterization has not been defined. Herein we examine the TAH in terms of elastance using a non-ejecting left-ventricle, and then characterize the pressure-volume relationship of the TAH by varying preload and afterload parameters using a Donovan Mock Circulatory System. We demonstrate that the TAH does not operate with time-varying elastance, differing from the human heart. Further, we show that the TAH has a pressure-volume relationship behavior that also differs from that of the human heart. The TAH does exhibit Starling-like behavior, with output increasing via preload dependent mechanisms, without reliance on an alteration of inotropic state within the operating window of the TAH. Within our testing range, the TAH is insensitive to variations in afterload, however this insensitivity has a limit, the limit being the maximum driving pressure of the pneumatic driver. Understanding the physiology of the TAH affords insight into the functional parameters that govern artificial heart behavior providing perspective on differences compared to the human heart. PMID:25551416
Crosby, Jessica R; DeCook, Katrina J; Tran, Phat L; Smith, Richard G; Larson, Douglas F; Khalpey, Zain I; Burkhoff, Daniel; Slepian, Marvin J
The SynCardia total artificial heart (TAH) has emerged as an effective, life-saving biventricular replacement system for a wide variety of patients with end-stage heart failure. Although the clinical performance of the TAH is established, modern physiological characterization, in terms of elastance behavior and pressure-volume (PV) characterization has not been defined. Herein, we examine the TAH in terms of elastance using a nonejecting left ventricle, and then characterize the PV relation of the TAH by varying preload and afterload parameters using a Donovan Mock Circulatory System. We demonstrate that the TAH does not operate with time-varying elastance, differing from the human heart. Furthermore, we show that the TAH has a PV relation behavior that also differs from that of the human heart. The TAH does exhibit Starling-like behavior, with output increasing via preload-dependent mechanisms, without reliance on an alteration of inotropic state within the operating window of the TAH. Within our testing range, the TAH is insensitive to variations in afterload; however, this insensitivity has a limit, the limit being the maximum driving pressure of the pneumatic driver. Understanding the physiology of the TAH affords insight into the functional parameters that govern artificial heart behavior providing perspective on differences compared with the human heart.
Abraham, William T.; Smith, Sakima A.
Heart failure (HF) is a global phenomenon, and the overall incidence and prevalence of the condition are steadily increasing. Medical therapies have proven efficacious, but only a small number of pharmacological options are in development. When patients cease to respond adequately to optimal medical therapy, cardiac resynchronization therapy has been shown to improve symptoms, reduce hospitalizations, promote reverse remodelling, and decrease mortality. However, challenges remain in identifying the ideal recipients for this therapy. The field of mechanical circulatory support has seen immense growth since the early 2000s, and left ventricular assist devices (LVADs) have transitioned over the past decade from large, pulsatile devices to smaller, more-compact, continuous-flow devices. Infections and haematological issues are still important areas that need to be addressed. Whereas LVADs were once approved only for ‘bridge to transplantation’, these devices are now used as destination therapy for critically ill patients with HF, allowing these individuals to return to the community. A host of novel strategies, including cardiac contractility modulation, implantable haemodynamic-monitoring devices, and phrenic and vagus nerve stimulation, are under investigation and might have an impact on the future care of patients with chronic HF. PMID:23229137
Kiris, Cetin; Chang, I-Dee; Rogers, Stuart E.; Kwak, Dochan
A numerical simulation of the incompressible viscous flow through a prosthetic tilting disk heart valve is presented in order to demonstrate the current capability to model unsteady flows with moving boundaries. Both steady state and unsteady flow calculations are done by solving the incompressible Navier-Stokes equations in 3-D generalized curvilinear coordinates. In order to handle the moving boundary problems, the chimera grid embedding scheme which decomposes a complex computational domain into several simple subdomains is used. An algebraic turbulence model for internal flows is incorporated to reach the physiological values of Reynolds number. Good agreement is obtained between the numerical results and experimental measurements. It is found that the tilting disk valve causes large regions of separated flow, and regions of high shear.
Pokorný, M; Cervenka, L; Netuka, I; Pirk, J; Koňařík, M; Malý, J
Ventricular assist devices (VAD) have recently established themselves as an irreplaceable therapeutic modality of terminal heart failure. Because of the worldwide shortage of donors, ventricular assist devices play a key role in modern heart failure therapy. Some clinical data have revealed the possibility of cardiac recovery during VAD application. On the other hand, both clinical and experimental studies indicate the risk of the cardiac atrophy development, especially after prolonged mechanical unloading. Little is known about the specific mechanisms governing the unloading-induced cardiac atrophy and about the exact ultrastructural changes in cardiomyocytes, and even less is known about the ways in which possible therapeutical interventions may affect heart atrophy. One aim of this review was to present important aspects of the development of VAD-related cardiac atrophy in humans and we also review the most significant observations linking clinical data and those derived from studies using experimental models. The focus of this article was to review current methods applied to alleviate cardiac atrophy which follows mechanical unloading of the heart. Out of many pharmacological agents studied, only the selective beta2 agonist clenbuterol has been proved to have a significantly beneficial effect on unloading-induced atrophy. Mechanical means of atrophy alleviation also seem to be effective and promising.
Sonntag, Simon J.; Kaufmann, Tim A. S.; Büsen, Martin R.; Laumen, Marco; Linde, Torsten; Schmitz-Rode, Thomas; Steinseifer, Ulrich
Heart disease is one of the leading causes of death in the world. Due to a shortage in donor organs artificial hearts can be a bridge to transplantation or even serve as a destination therapy for patients with terminal heart insufficiency. A pusher plate driven pulsatile membrane pump, the Total Artificial Heart (TAH) ReinHeart, is currently under development at the Institute of Applied Medical Engineering of RWTH Aachen University.This paper presents the methodology of a fully coupled three-dimensional time-dependent Fluid Structure Interaction (FSI) simulation of the TAH using a commercial partitioned block-Gauss-Seidel coupling package. Partitioned coupling of the incompressible fluid with the slender flexible membrane as well as a high fluid/structure density ratio of about unity led inherently to a deterioration of the stability (‘artificial added mass instability’). The objective was to conduct a stable simulation with high accuracy of the pumping process. In order to achieve stability, a combined resistance and pressure outlet boundary condition as well as the interface artificial compressibility method was applied. An analysis of the contact algorithm and turbulence condition is presented. Independence tests are performed for the structural and the fluid mesh, the time step size and the number of pulse cycles. Because of the large deformation of the fluid domain, a variable mesh stiffness depending on certain mesh properties was specified for the fluid elements. Adaptive remeshing was avoided. Different approaches for the mesh stiffness function are compared with respect to convergence, preservation of mesh topology and mesh quality. The resulting mesh aspect ratios, mesh expansion factors and mesh orthogonalities are evaluated in detail. The membrane motion and flow distribution of the coupled simulations are compared with a top-view recording and stereo Particle Image Velocimetry (PIV) measurements, respectively, of the actual pump.
Argiriou, Mihalis; Kolokotron, Styliani-Maria; Sakellaridis, Timothy; Argiriou, Orestis; Charitos, Christos; Katsikogiannis, Nikolaos; Kougioumtzi, Ioanna; Machairiotis, Nikolaos; Tsiouda, Theodora; Tsakiridis, Kosmas; Zarogoulidis, Konstantinos
Right heart failure (RHF) is a frequent complication following left ventricular assist device (LVAD) implantation. The incidence of RHF complicates 20-50% (range, 9-44%) of cases and is a major factor of postoperative morbidity and mortality. Unfortunately, despite the fact that many risk factors contributing to the development of RHF after LVAD implantation have been identified, it seems to be extremely difficult to avoid them. Prevention of RHF consists of the management of the preload and the afterload of the right ventricle with optimum inotropic support. The administration of vasodilators designed to reduce pulmonary vascular resistance is standard practice in most centers. The surgical attempt of implantation of a right ventricular assist device does not always resolve the problem and is not available in all cardiac surgery centers. PMID:24672699
Argiriou, Mihalis; Kolokotron, Styliani-Maria; Sakellaridis, Timothy; Argiriou, Orestis; Charitos, Christos; Zarogoulidis, Paul; Katsikogiannis, Nikolaos; Kougioumtzi, Ioanna; Machairiotis, Nikolaos; Tsiouda, Theodora; Tsakiridis, Kosmas; Zarogoulidis, Konstantinos
Right heart failure (RHF) is a frequent complication following left ventricular assist device (LVAD) implantation. The incidence of RHF complicates 20-50% (range, 9-44%) of cases and is a major factor of postoperative morbidity and mortality. Unfortunately, despite the fact that many risk factors contributing to the development of RHF after LVAD implantation have been identified, it seems to be extremely difficult to avoid them. Prevention of RHF consists of the management of the preload and the afterload of the right ventricle with optimum inotropic support. The administration of vasodilators designed to reduce pulmonary vascular resistance is standard practice in most centers. The surgical attempt of implantation of a right ventricular assist device does not always resolve the problem and is not available in all cardiac surgery centers.
Rivera, Marcelino E; Linder, Brian J; Ziegelmann, Matthew J; Viers, Boyd R; Rangel, Laureano J; Elliott, Daniel S
The literature on artificial urinary sphincter device survival in individuals with a history of radiation therapy is conflicting. We assess device survival outcomes among individuals after prior radiation therapy exposure undergoing primary artificial urinary sphincter placement. An institutional review board approved database of all patients who underwent artificial urinary sphincter surgery from 1999 to 2011 was used to assess device survival in patients treated with radiotherapy compared to individuals without radiotherapy exposure. Hazard regression and competing risk analysis were used to determine the association between radiation therapy and device outcomes. From 1999 to 2011 a total of 872 patients underwent artificial urinary sphincter surgery at our institution. Of these patients 489 underwent primary artificial urinary sphincter placement, with 181 of 489 (37%) having received radiation therapy. Patients with prior radiation therapy were older (median age 72.0 vs 70.1 years, p <0.01) and had a higher median body mass index (29.4 vs 28.6 kg/m(2), p <0.03) than those without radiation exposure. Rates of diabetes mellitus and hypertension were similar between the 2 groups. There was no significant difference in overall device survival between individuals who received radiation therapy and those without radiation therapy exposure, with 1 and 5-year device survival rates of 92% vs 90% and 77% vs 74%, respectively (p=0.24). While individuals who underwent radiation therapy were significantly older and had a higher body mass index, device survival was not significantly different between the 2 groups when using a cuff size greater than 3.5 cm. These findings will assist the urologist with the preoperative counseling of men undergoing primary artificial urinary sphincter placement with a history of radiation therapy. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
Enthusiasm for liver support devices, particularly cell-based biological systems and albumin dialysis, increased over the last decade and there has been considerable clinical activity both within and without the construct of clinical trials. Most data have been generated on patients with acute liver failure or in patients with decompensation of chronic liver disease, often referred to as acute-on-chronic liver failure. In acute liver failure liver, liver support devices are more realistically being used as a 'bridge' to liver transplantation rather than to transplant-free survival. In acute-on-chronic liver failure the clinical objective of attaining clinical stability with treatment appears more achievable. The so-called bioartificial liver device, based on porcine hepatocytes, is the most extensively evaluated biological device. A sizeable clinical trial failed to demonstrate efficacy, but secondary analyses suggest it would be unwise to assume futility had been established with this device. Molecular adsorbent recirculating system leads the way in the non-biological category in terms of the number of patients treated, but data from large clinical trials are not yet available. One of the strongest conclusions of this review is that the amount of high-quality data available on liver support devices dramatically understates the effort and money that have been expended in their assessment. It is very clear that randomized controlled trials are mandatory to establish clinical efficacy, but it is less clear how the ideal trial should be constructed.
Cerier, Emily; Lampert, Brent C; Kilic, Arman; McDavid, Asia; Deo, Salil V; Kilic, Ahmet
Advanced heart failure has been traditionally treated via either heart transplantation, continuous inotropes, consideration for hospice and more recently via left ventricular assist devices (LVAD). Heart transplantation has been limited by organ availability and the futility of other options has thrust LVAD therapy into the mainstream of therapy for end stage heart failure. Improvements in technology and survival combined with improvements in the quality of life have made LVADs a viable option for many patients suffering from heart failure. The question of when to implant these devices in those patients with advanced, yet still ambulatory heart failure remains a controversial topic. We discuss the current state of LVAD therapy and the risk vs benefit of these devices in the treatment of heart failure. PMID:28070237
Hoyer, D; Schmidt, K; Zwiener, U
The aim of the present paper was, using artificial neural networks, to identify chaotic attractors presumed to be responsible for heart rate fluctuations. Chaotic behaviour is based on low-dimensional deterministic processes which are highly sensitive to initial conditions and therefore of limited predictability. Chaotic attractors produce orbits in the phase space where the points are dense. Following transformation of measured heart rate date into the phase space, such heart rate prediction characteristics were found in 6 adult rabbits. A low-dimensional deterministic model was designed by means of an artificial neural network [2*dimension of the time series +1) input neurons, 1 hidden layer, 1 output neuron and was successfully employed to predict the next 5 heart beats. Training of the neural network in terms of the prediction of the suspected chaotic orbits was dramatically improved by considering all possible prediction intervals within the prediction horizon. The trained models enabled the heart rate fluctuations to be distinguished during consciousness, under anaesthesia and additional vagal blockade.
Ha, Roy R; Wang, Dongfang; Zwischenberger, Joseph B; Clark, John W
We have extended our model of the ovine pulmonary circulation to include a model of a paracorporeal artificial lung (AL) and its attachments to the natural pulmonary circulation in two configurations: in series and in parallel. Our model of the natural lung (NL) circulation is first shown to be in agreement with hemodynamic and input impedance data from the open literature. We then study design efficacy of the AL in terms of its housing and attachments. A sensitivity analysis of the modified pulmonary circulation model reveals that there are three key parameters: inlet graft length (IGL) and the compliances of the inlet compliance chamber (CC) and housing of the artificial lung. Based on literature reports, we assume the right ventricle is well-matched to the impedance of the natural pulmonary circulation and adjust the parameters of the modeled AL circuit to achieve the best least-squares fit to natural pulmonary input impedance data. Best-fit parameters produce impedance curves that fit natural impedance well, particularly below 3 Hz, where both compliance and graft length have their largest effects. Of these parameters, the impedance profile is most sensitive to IGL. However, the compliances are important, as well, particularly at low frequencies.
Yafi, Faysal A; DeLay, Kenneth J; Stewart, Carrie; Chiang, Jason; Sangkum, Premsant; Hellstrom, Wayne J G
The AMS 800™ artificial urinary sphincter remains the gold standard for the surgical management of male stress urinary incontinence. We reviewed artificial urinary sphincter device survival after primary implantation. Retrospective data were collected from the AMS 800 patient information form database. Since 1972, 77,512 patient information forms for primary artificial urinary sphincter implantation have been completed in the United States. Following exclusion of procedures performed in children and females, and those labeled with an unknown surgical technique, 27,096 artificial urinary sphincter cases were included in the analysis. Collected variables included patient age, surgical approach, number of cuffs and surgeon volume. Measured outcomes included device explantation, device revision, component revision and time to each event. Artificial urinary sphincter insertion was performed by low volume implanters in 22,165 (82.6%) cases. The approach was perineal in 18,373 cases (67.8%) and a tandem cuff was used in 2,224 cases (8.2%). Overall 5,723 cases required revision or explantation (21.1%). Younger age and penoscrotal approach were associated with higher device explantation and revision rates, while the use of a tandem cuff was associated with higher explantation rates. On multivariate analysis younger age, penoscrotal approach and use of a tandem cuff but not surgeon volume were significant factors associated with device explantation and component revision. These data provide a general overview of artificial urinary sphincter device survival and may serve urologists when counseling patients. Younger age, penoscrotal approach and use of a tandem cuff may be associated with inferior outcomes. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
Shim, Eun Bo; Yeo, Jong Young; Ko, Hyung Jong; Youn, Chan Hyun; Lee, Young Ro; Park, Chan Young; Min, Byoung Goo; Sun, Kyung
Flow in the blood sac of the Korean artificial heart is numerically simulated by finite element method. Fluid-structure interaction algorithm is employed to compute the three-dimensional blood flow interacting with the sac material. For verification of the numerical method of fluid-structure interaction, two-dimensional flow in a collapsible channel with initial tension is simulated and the results are compared with numerical solutions from the literature. Incompressible viscous flow and linear elastic solid are assumed for the blood and the sac material in the device, respectively. The motion of the actuator is simplified by a time-varying pressure boundary condition imposed on the outer surface of the sac. Numerical solutions on the unsteady three-dimensional blood flow in the sac are provided for the cactus-type model in this study. During systole, the inlet is closed and the blood sac is squeezed by the action of the prescribed pressure on the surface. During diastole, the sac is filled with the blood coming from the inlet while the outlet is closed. A strong flow to the outlet and a stagnated flow near the inlet are observed during systole. Shear stress distribution is also delineated to assess the possibility of thrombus formation. We also simulate numerically the hemodynamics of "the reversed model" where the inlet and outlet are reversed for surgical convenience. It is observed that a recirculating flow was generated near the inner corner of the sac in the reversed model. To assess the material strength of the sac, the shear stress distribution in the solid material is also presented.
Lee, Dong Hyuk; Seo, Soo W.; Min, Byong Goo
Artificial heart valve is one of the most important artificial organs which have been implanted to many patients. The most serious problems related to the artificial heart valve prothesis are thrombosis and hemolysis. In vivo experiment to test against this problem is complex and hard work. Nowadays the request for in vitro artificial heart valve testing system is increasing. Several papers have announced us that the flow pattern of artificial heart valve is highly correlated with thrombosis and hemolysis. LDA is a usual method to get flow pattern, which is difficult to operate, is expensive and has narrow measure region. PIV (Particle Image Velocimetry) can solve these problems. Because the flow speed of valve is too high to catch particles by CCD camera and high-speed camera (Hyspeed; Holland-Photonics) was used. The estimated max flow speed was 5 m/sec and max trackable length is 0.5 cm, so the shutter speed was determined as 1000 frames per sec. Several image processing techniques (blurring, segmentation, morphology, etc.) were used for the preprocessing. Particle tracking algorithm and 2D interpolation technique which were necessary in making gridrized velocity profile, were applied to this PIV program. By using Single- Pulse Multi-Frame particle tracking algorithm, some problems of PIV can be solved. To eliminate particles which penetrate the sheeted plane and to determine the direction of particle paths are these. 1D relaxation formula is modified to interpolate 2D field. Parachute artificial heart valve which was developed by Scoul National University and Bjork-Shiely valve was testified. For each valve, different flow pattern, velocity profile, wall shear stress, turbulence intensity profile and mean velocity were obtained. Those parameters were compared with the result of in vivo experiment. In this experiment we can conclude wall shear stress is not high enough to generate hemolysis and higher turbulence intensity to make more hemolysis. For further
Huffman, Fred N.; Hagen, Kenneth G.; Whalen, Robert L.; Fuqua, John M.; Norman, John C.
The feasibility of radioisotope-fueled circulatory support systems depends on the ability of the body to dissipate the reject heat from the power source driving the blood pump as well as to tolerate chronic intracorporeal radiation. Our studies have focused on the use of the circulating blood as a heat sink. Initial in vivo heat transfer studies utilized straight tube heat exchangers (electrically and radioisotope energized) to replace a segment of the descending aorta. More recent studies have used a left ventricular assist pump as a blood-cooled heat exchanger. This approach minimizes trauma, does not increase the area of prosthetic interface with the blood, and minimizes system volume. Heat rejected from the thermal engine (vapor or gas cycle) is transported from the nuclear power source in the abdomen to the pump in the thoracic cavity via hydraulic lines. Adjacent tissue is protected from the fuel capsule temperature (900 to 1200°F) by vacuum foil insulation and polyurethane foam. The in vivo thermal management problems have been studied using a simulated thermal system (STS) which approximates the heat rejection and thermal transport mechanisms of the nuclear circulatory support systems under development by NHLI. Electric heaters simulate the reject heat from the thermal engines. These studies have been essential in establishing the location, suspension, surgical procedures, and postoperative care for implanting prototype nuclear heart assist systems in calves. The pump has a thermal impedance of 0.12°C/watt. Analysis of the STS data in terms of an electrical analog model implies a heat transfer coefficient of 4.7 × 10−3 watt/cm2°C in the abdomen compared to a value of 14.9 × 10−3 watt/cm2°C from the heat exchanger plenum into the diaphragm. Images PMID:15215968
Wyller, Vegard Bruun; Aaberge, Lars; Thaulow, Erik; Døhlen, Gaute
Percutaneous catheter-based implantation of artificial heart valves is a new technique that may supplement surgery and which may be used more in the future. We here report our first experience with implantation of artificial pulmonary valves in children with congenital heart defects. Eligible patients were those with symptoms of heart failure combined with stenosis and/or insufficiency in an established artificial right ventricular outflow tract. The valve was inserted through a catheter from a vein in the groin or neck. Symptoms, echocardiography, invasive measurements and angiography were assessed for evaluation of treatment effect. Our treatment results are reported for the period April 2007-September 2009. Ten patients (seven men and three women, median age 17 years) were assessed. The procedure reduced pressure in the right ventricle (p = 0.008) and resolved the pulmonary insufficiency in all patients. The median time in hospital was two days. No patients had complications that were directly associated with the implantation procedure. One patient developed a pseudoaneurysm in the femoral artery, another had a short-lasting fever two days after the procedure and one patient experienced a stent fracture that required surgery 9 months after the implantation. After 6 months all patients had a reduced pressure gradient in the right ventricular outflow tract (p = 0.008), the pulmonary insufficiency had improved (p = 0.006) and they all reported improval of symptoms. These results persisted for at least 24 months for the four patients who were monitored until then. Percutaneous catheter-based implantation of artificial pulmonary valves improves hemodynamics in the right ventricle of selected patients with congenital heart defects. A randomized controlled study should be undertaken to provide a stronger evidence-base for usefulness of this procedure.
Vortex matter in superconducting films and devices is not only an interesting topic for basic research but plays a substantial role in the applications of superconductivity in general. We demonstrate, that in most electronic applications, magnetic flux penetrates the superconductor and affects the performance of superconducting devices. Therefore, vortex manipulation turns out to be a useful tool to avoid degradation of superconducting device properties. Moreover, it can also be used to analyze and understand novel and interesting physical properties and develop new concepts for superconductor applications. In this review, various concepts for vortex manipulation are sketched. For example, the use of micro- and nanopatterns (especially, antidots) for guiding and trapping of vortices in superconducting films and thin film devices is discussed and experimental evidence of their vortex guidance and vortex trapping by various arrangements of antidots is given. We demonstrate, that the vortex state of matter is very important in applications of superconductivity. A better understanding does not only lead to an improvement of the performance of superconductor components, such as reduced noise, better power handling capability, or improved reliability, it also promises deeper insight into the basic physics of vortices and vortex matter.
Miura, H; Saito, I; Sato, F; Shiraishi, Y; Yambe, T; Matsuki, H
A new control method for stabilizing output voltage of the transcutaneous energy transmission system for artificial heart is proposed. This method is primary side, is outside of the body, which is not depending on a signal transmission system from the implanted device. The impedance observed from primary side changes from inductive to capacitive and the output voltage decreases drastically when the output current is large and the coupling factor is higher than that of the optimal condition. In this case, the driving frequency should be changed to higher so that the phase angle of the primary impedance is zero degree. The preliminary examination showed that this control method can enhance the output voltage limit to twice and the feasibility of the primary side control.
Prasad, Amit; Ghodsizad, Ali; Pae, Walter; Singbartl, Kai; Boone, Jacqueline; Zeriouh, M; Ruhparwar, Arjang; Loebe, M; Khorrami, G Sadat Hoesseini; Koerner, Michael M; Brehm, Christoph
The Syncardia™ total artificial heart (TAH) is an option for patients as a bridge to transplant in those who are not candidates for left ventricular assist devices (LVAD) due to right ventricular failure. Postoperative course is highly dependent on volume status and aggressive diuresis is often necessary. One complication from aggressive diuresis is hypokalemia; however, in these patients we tolerate a lower potassium level because cardiac arrhythmias are not a concern. However, in two separate instances non-cardiac symptoms related to severe hypokalemia occurred. These symptoms included nystagmus in one patient and agitation, tremors, and having an "out-of-body" experience in the other patient. Both these patients had resolution of symptoms with potassium replacement.
Yambe, T; Abe, Y; Yoshizawa, M; Imachi, K; Tabayashi, K; Takayasu, H; Takeda, H; Gouhara, K; Nitta, S
To evaluate the automatic control algorithm of the total artificial heart (TAH) as an entity, and not just as parts, a non-linear mathematical analyzing technique including chaos theory was utilized. Chronic experiments on the biventricular bypass type artificial heart implantation were performed in healthy adult goats after the natural ventricles were removed. Hemodynamic time series data were recorded under the awake standing condition with TAH 1/R and fixed driving. Time series data were recorded on a magnetic tape and analyzed on a personal computer system with an A-D converter. Using the nonlinear mathematical technique, the time series data were embedded into the phase space and the Lyapunov numerical method was carried out for the quantitative evaluation of the sensitive dependence on the initial condition of the reconstructed attractor. Calculation of the largest Lyapunov exponents suggested that the reconstructed attractor of the left pump output during TAH 1/R control was a larger dimensional strange attractor, a characteristic pattern of deterministic chaos. A total system indicating chaotic dynamics was thought to be a flexible and intelligent control system. Thus, our results suggest that 1/R TAH control may be suitable for the biventricular assist type total artificial heart.
AlHabeeb, Waleed; AlAyoubi, Fakhr; Tash, Adel; AlAhmari, Leenah; AlHabib, Khalid F
To understand the attitudes of the Saudi population towards heart donation and transplantation. Methods: A survey using a questionnaire addressing attitudes towards organ transplantation and donation was conducted across 18 cities in Saudi Arabia between September 2015 and March 2016. Results: A total of 1250 respondents participated in the survey. Of these, approximately 91% agree with the concept of organ transplantation but approximately 17% do not agree with the concept of heart transplantation; 42.4% of whom reject heart transplants for religious reasons. Only 43.6% of respondents expressed a willingness to donate their heart and approximately 58% would consent to the donation of a relative's organ after death. A total of 59.7% of respondents believe that organ donation is regulated and 31.8% fear that the doctors will not try hard enough to save their lives if they consent to organ donation. Approximately 77% believe the heart is removed while the donor is alive; although, the same proportion of respondents thought they knew what brain death meant. Conclusion: In general, the Saudi population seem to accept the concept of transplantation and are willing to donate, but still hold some reservations towards heart donation.
AlHabeeb, Waleed; AlAyoubi, Fakhr; Tash, Adel; AlAhmari, Leenah; AlHabib, Khalid F.
Objectives: To understand the attitudes of the Saudi population towards heart donation and transplantation. Methods: A survey using a questionnaire addressing attitudes towards organ transplantation and donation was conducted across 18 cities in Saudi Arabia between September 2015 and March 2016. Results: A total of 1250 respondents participated in the survey. Of these, approximately 91% agree with the concept of organ transplantation but approximately 17% do not agree with the concept of heart transplantation; 42.4% of whom reject heart transplants for religious reasons. Only 43.6% of respondents expressed a willingness to donate their heart and approximately 58% would consent to the donation of a relative’s organ after death. A total of 59.7% of respondents believe that organ donation is regulated and 31.8% fear that the doctors will not try hard enough to save their lives if they consent to organ donation. Approximately 77% believe the heart is removed while the donor is alive; although, the same proportion of respondents thought they knew what brain death meant. Conclusion: In general, the Saudi population seem to accept the concept of transplantation and are willing to donate, but still hold some reservations towards heart donation. PMID:28674721
Cohrs, Nicholas H; Petrou, Anastasios; Loepfe, Michael; Yliruka, Maria; Schumacher, Christoph M; Kohll, A Xavier; Starck, Christoph T; Schmid Daners, Marianne; Meboldt, Mirko; Falk, Volkmar; Stark, Wendelin J
The technology of 3D-printing has allowed the production of entirely soft pumps with complex chamber geometries. We used this technique to develop a completely soft pneumatically driven total artificial heart from silicone elastomers and evaluated its performance on a hybrid mock circulation. The goal of this study is to present an innovative concept of a soft total artificial heart (sTAH). Using the form of a human heart, we designed a sTAH, which consists of only two ventricles and produced it using a 3D-printing, lost-wax casting technique. The diastolic properties of the sTAH were defined and the performance of the sTAH was evaluated on a hybrid mock circulation under various physiological conditions. The sTAH achieved a blood flow of 2.2 L/min against a systemic vascular resistance of 1.11 mm Hg s/mL (afterload), when operated at 80 bpm. At the same time, the mean pulmonary venous pressure (preload) was fixed at 10 mm Hg. Furthermore, an aortic pulse pressure of 35 mm Hg was measured, with a mean aortic pressure of 48 mm Hg. The sTAH generated physiologically shaped signals of blood flow and pressures by mimicking the movement of a real heart. The preliminary results of this study show a promising potential of the soft pumps in heart replacements. Further work, focused on increasing blood flow and in turn aortic pressure is required. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Cipriani, Manlio; Macera, Francesca; Verde, Alessandro; Bruschi, Giuseppe; del Medico, Marta; Oliva, Fabrizio; Martinelli, Luigi; Frigerio, Maria
Women candidates for heart transplantation are definitely less than men, just 20% of all patients transplanted; even in the INTERMACS registry they represent only 21% of all ventricular assist devices (VAD) implanted. The reasons for this big difference are discussed in this article. Why women are less frequently assessed for unconventional therapies? Are they sicker or just less regarded? Our experience and the literature show us clear epidemiological, clinical and treatment differences that could lead to a lower prevalence of end-stage disease in women of an age suitable for unconventional therapies. Once on the transplant list, women wait less than men for a heart transplant, because they present with more severe disease, have a lower body mass index and undergo less VAD implants. After transplantation women's survival is comparable to men's, although they usually complain of a lower quality of life. Females receive less often a VAD than men. The main reasons for this include presentation with advanced heart failure at an older age than men, worse outcomes related to small body surface area, and lower survival rates on VAD when implanted as bridge to heart transplantation.
Tchin-Iou, A V; Min, B G
The solar cell as the advanced alternative energy resource was found to be acceptable for increasing battery running time of the totally-implantable artificial heart. A sample of the wireless charging system with solar cell base gives a maximum battery running time around 9 hours and some physical and psychological freedom to the patient. This improvement will assist the application of the implantable artificial heart for a longer period of time and with added convenience to the recipient.
Martin, Jeremiah T; Zwischenberger, Joseph B
There is a growing demand for new technology that can take over the function of the human lung, whether it is to assist an injured or recently transplanted lung or to completely replace the native lung. The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation was reported for the first time more than 3 decades ago; nevertheless, its use in lung transplantation was largely abandoned owing to poor patient survival and frequent complications. ECMO as a bridge to lung transplantation has significantly increased during the past 10 years. This increase in utilization is reflected in the growing success reported with the use of different ECMO modalities in patients awaiting lung transplantation. The use of ECMO is now being considered in awake and nonintubated patients so as to improve oxygenation, facilitate ambulation, and improve physical conditioning before transplant. Several programs have developed ambulatory capability of most forms of ECMO, and ambulatory ECMO is now often referred to as the "artificial lung." We present a brief description of the evolution of the use of ECMO in lung transplantation and summarize the available technology and current approaches to provide ECMO support.
Saijo, Y; Okawai, H; Sasaki, H; Yambe, T; Nitta, S; Tanaka, M; Kobayashi, K; Honda, Y
The total artificial heart (TAH) is being developed for permanent replacement of the natural heart instead of heart transplantation. The need for detecting the material fatigue in the TAH is increasing in order to guarantee long-term use. In this study, the inner surface morphology of the TAH was evaluated by a specially developed scanning acoustic microscope (SAM) system operating in the frequency range of 100-200 MHz. The inner sac of our TAH consisted of polyvinylchloride coated with polyurethane, and the SAM investigations were performed before and after the implantations in goats. The amplitude images of the SAM demonstrated protein adhesion on the inner surface of the TAH after the animal experiment, and the phase images showed distortion of the wall with spatial resolution of 0.2 microm. These results suggest the feasibility of a high-frequency ultrasound for evaluating the material fatigue of TAH.
Russell, Steven J.
Purpose of review This article describes recent progress in the automated control of glycemia in type 1 diabetes with artificial pancreas devices that combine continuous glucose monitoring with automated decision-making and insulin delivery. Recent findings After a gestation period of closely supervised feasibility studies in research centers, the last 2 years have seen publication of studies testing these devices in outpatient environments, and many more such studies are ongoing. The most basic form of automation, suspension of insulin delivery for actual or predicted hypoglycemia, has been shown to be effective and well tolerated, and a first-generation device has actually reached the market. Artificial pancreas devices that actively dose insulin fall into two categories, those that dose insulin alone and those that also use glucagon to prevent and treat hypoglycemia (bihormonal artificial pancreas). Initial outpatient clinical trials have shown that both strategies can improve glycemic management in comparison with patient-controlled insulin pump therapy, but only the bihormonal strategy has been tested without restrictions on exercise. Summary Artificial pancreas technology has the potential to reduce acute and chronic complications of diabetes and mitigate the burden of diabetes self-management. Successful outpatient studies bring these technologies one step closer to availability for patients. PMID:25692927
Hanna, Ramy M; Hasnain, Huma; Kamgar, Mohammad; Hanna, Mina; Minasian, Raffi; Wilson, James
Advanced mechanical circulatory support is increasingly being used with more sophisticated devices that can deliver pulsatile rather than continuous flow. These devices are more portable as well, allowing patients to await cardiac transplantation in an outpatient setting. It is known that patients with renal failure are at increased risk for developing worsening acute kidney injury during implantation of a ventricular assist device (VAD) or more advanced modalities like a total artificial heart (TAH). Dealing with patients who have an implanted TAH who develop renal failure has been a challenge with the majority of such patients having to await a combined cardiac and renal transplant prior to transition to outpatient care. Protocols do exist for VAD implanted patients to be transitioned to outpatient dialysis care, but there are no reported cases of TAH patients with end stage renal disease (ESRD) being successfully transitioned to outpatient dialysis care. In this report, we identify a patient with a TAH and ESRD transitioned successfully to outpatient hemodialysis and maintained for more than 2 years, though he did not survive to transplant. It is hoped that this report will raise awareness of this possibility, and assist in the development of protocols for similar patients to be successfully transitioned to outpatient dialysis care. © 2017 International Society for Hemodialysis.
Marom, Gil; Chiu, Wei-Che; Crosby, Jessica R; DeCook, Katrina J; Prabhakar, Saurabh; Horner, Marc; Slepian, Marvin J; Bluestein, Danny
The SynCardia total artificial heart (TAH) is the only Food and Drug Administration (FDA) approved device for replacing hearts in patients with congestive heart failure. It pumps blood via pneumatically driven diaphragms and controls the flow with mechanical valves. While it has been successfully implanted in more than 1300 patients, its size precludes implantation in smaller patients. This study's aim was to evaluate the viability of scaled-down TAHs by quantifying thrombogenic potentials from flow patterns. Simulations of systole were first conducted with stationary valves, followed by an advanced full-cardiac cycle model with moving valves. All the models included deforming diaphragms and platelet suspension in the blood flow. Flow stress accumulations were computed for the platelet trajectories and thrombogenic potentials were assessed. The simulations successfully captured complex flow patterns during various phases of the cardiac cycle. Increased stress accumulations, but within the safety margin of acceptable thrombogenicity, were found in smaller TAHs, indicating that they are clinically viable.
Wu, Guodong; Feng, Ping; Wan, Xiang; Zhu, Liqiang; Shi, Yi; Wan, Qing
Recent progress in using biomaterials to fabricate functional electronics has got growing attention for the new generation of environmentally friendly and biocompatible electronic devices. As a kind of biological material with rich source, proteins are essential natural component of all organisms. At the same time, artificial synaptic devices are of great significance for neuromorphic systems because they can emulate the signal process and memory behaviors of biological synapses. In this report, natural chicken albumen with high proton conductivity was used as the coupling electrolyte film for organic/inorganic hybrid synaptic devices fabrication. Some important synaptic functions including paired-pulse facilitation, dynamic filtering, short-term to long-term memory transition and spatial summation and shunting inhibition were successfully mimicked. Our results are very interesting for biological friendly artificial neuron networks and neuromorphic systems.
Wu, Guodong; Feng, Ping; Wan, Xiang; Zhu, Liqiang; Shi, Yi; Wan, Qing
Recent progress in using biomaterials to fabricate functional electronics has got growing attention for the new generation of environmentally friendly and biocompatible electronic devices. As a kind of biological material with rich source, proteins are essential natural component of all organisms. At the same time, artificial synaptic devices are of great significance for neuromorphic systems because they can emulate the signal process and memory behaviors of biological synapses. In this report, natural chicken albumen with high proton conductivity was used as the coupling electrolyte film for organic/inorganic hybrid synaptic devices fabrication. Some important synaptic functions including paired-pulse facilitation, dynamic filtering, short-term to long-term memory transition and spatial summation and shunting inhibition were successfully mimicked. Our results are very interesting for biological friendly artificial neuron networks and neuromorphic systems. PMID:27008981
Doyle, Matthew G; Vergniaud, Jean-Baptiste; Tavoularis, Stavros; Bourgault, Yves
This article describes two ongoing numerical studies of fluid-structure interaction in the cardiovascular system: an idealized pulsatile ventricular assist device (VAD), consisting of two fluid chambers separated by a flexible diaphragm; and blood flow and heart wall motion during passive filling of a canine heart. Simulations have been performed for the VAD and compared with the results of a previous study and to our own preliminary experimental results. Detailed measurements of the flow field in the VAD model and additional simulations are in progress. Preliminary simulations using both an idealized model of the natural heart as well as a realistic model have identified the limitations of the current numerical methods in dealing with large three-dimensional deformations. Ongoing research aims at extending the range of simulations to include large deformations and to incorporate an anisotropic material model for the heart wall to account for the muscle fibers.
Masuzawa, T; Taenaka, Y; Kinoshita, M; Nakatani, T; Akagi, H; Takano, H; Fukui, Y; Sasagawa, H; Takahashi, K
The authors have developed a new actuator to drive an electrohydraulic totally implantable artificial heart. The basic concept of this artificial heart is that the blood pumps are implanted in the thorax and an actuator is placed separately in the abdominal region. The actuator is a regenerative pump that pumps fluids against high pressures and is thin enough for easy implantation. The rotor-magnet of the brushless DC motor is mounted on the impeller of the pump to miniaturize the actuator and reduce the number of moving parts. The height, diameter, and weight of the actuator are 32.5 mm, 73 mm, and 360 g, respectively. A pair of oil ports is connected to the left and right blood pumps with mesh reinforced tubes filled with silicone oil. The blood pumps are alternately driven by bidirectional rotation of the motor. Performance of the system was evaluated in in vitro and in vivo experiments. Maximum output of the right heart was 6.7 L/min in both experiments. Systemic circulation was well maintained in acute animal experiments using 49 and 50 kg goats. The feasibility of the actuator was confirmed.
Sakaguchi, Hirokazu; Kamei, Motohiro; Nishida, Kentaro; Terasawa, Yasuo; Fujikado, Takashi; Ozawa, Motoki; Nishida, Kohji
The purpose of this study was to investigate the surgical procedures involved in the implantation of a newly developed direct optic nerve electrode device for inducing artificial vision. The electrode device comprised seven wire stimulation electrodes and a return electrode (diameter 50 μm), one manipulation rod (diameter 100 μm), and a cylindrical silicone board (diameter 2.0 mm). The stimulation electrodes and the manipulation rod protruded through the board to allow implantation of the electrode tips into the optic disc of the rabbit eye. The surgical procedures required to insert the device into the vitreous cavity and implant the device into the optic disc were evaluated. When the electrodes were stimulated, electrically evoked potentials (EEPs) were recorded at the visual cortex. The electrode device was inserted into the vitreous cavity with no damage using a trocar through a scleral incision. The device was easily manipulated using vitreoretinal forceps in the vitreous cavity, and the electrode tips were implanted into the optic disc in a single insertion after vitrectomy. When electrical stimulation was applied, EEPs were recorded from all electrode pairs. The newly developed electrode device was inserted into the eye and implanted into the optic nerve disc smoothly and safely, suggesting that these surgical procedures are useful for our artificial vision system.
Moisseiev, Elad; Mannis, Mark J
Low vision is irreversible in many patients and constitutes a disability. When no treatment to improve vision is available, technological developments aid these patients in their daily lives. To evaluate the usefulness of a portable artificial vision device (OrCam) for patients with low vision. A prospective pilot study was conducted between July 1 and September 30, 2015, in a US ophthalmology department among 12 patients with visual impairment and best-corrected visual acuity of 20/200 or worse in their better eye. A 10-item test simulating activities of daily living was used to evaluate patients' functionality in 3 scenarios: using their best-corrected visual acuity with no low-vision aids, using low-vision aids if available, and using the portable artificial vision device. This 10-item test was devised for this study and is nonvalidated. The portable artificial vision device was tested at the patients' first visit and after 1 week of use at home. Scores on the 10-item daily function test. Among the 12 patients, scores on the 10-item test improved from a mean (SD) of 2.5 (1.6) using best-corrected visual acuity to 9.5 (0.5) using the portable artificial vision device at the first visit (mean difference, 7.0; 95% CI, 6.0-8.0; P < .001) and 9.8 (0.4) after 1 week (mean difference from the first visit, 7.3; 95% CI, 6.3-8.3; P < .001). Mean (SD) scores with the portable artificial vision device were also better in the 7 patients who used other low-vision aids (9.7 [0.5] vs 6.0 [2.6], respectively; mean difference, 3.7; 95% CI, 1.5-5.9; P = .01). When patients used a portable artificial vision device, an increase in scores on a nonvalidated 10-item test of activities of daily living was seen. Further evaluations are warranted to determine the usefulness of this device among individuals with low vision.
Wotke, Jiri; Homolka, Pavel; Vasku, Jaromír; Dobsak, Petr; Palanova, Petra; Mrkvicova, Veronika; Konecny, Petr; Soska, Vladimir; Pohanka, Michal; Novakova, Marie; Yurimoto, Terumi; Saito, Itsuro; Inoue, Yusuke; Isoyama, Takashi; Abe, Yusuke
Histopathological analysis can provide important information in long-term experiments with total artificial heart (TAH). Recently, a new type of blood pump, the helical flow total artificial heart (HF-TAH) was developed. This study aimed to investigate the changes in selected vital organs in animal experiments with implanted HF-TAH. Samples from lung, liver, and kidneys from two female goats (No. 1301 and No. 1304) with implanted HF-TAH were analyzed. Tissue samples were fixed in 10% formaldehyde and 4 µm thick transverse sections were stained with hematoxylin-eosin (HE). Additional staining was done for detection of connective tissue (Masson-Goldner stain) and for detection of iron (hemosiderin) deposits (Perls stain). Sections were scanned at 100× and 500× magnification with a light microscope. Experiment no. 1301 survived 100 days (cause of termination was heavy damage of the right pump); experimental goat no.1304 survived 68 days and was sacrificed due to severe right hydrodynamic bearing malfunction. Histopathological analysis of liver samples proved signs of chronic venostasis with limited focal necrotic zones. Dilated tubules, proteinaceous material in tubular lumen, and hemosiderin deposits were detected in kidney samples. Contamination of the organs by embolized micro-particles was suspected at the autopsy after discovery of visible damage (scratches) of the pump impeller surface (made from titanium alloy) in both experiments. Sporadic deposits of foreign micro-particles (presumably titanium) were observed in most of the analyzed parenchymal organs. However, the described deposits were not in direct connection with inflammatory reactions in the analyzed tissues. Histopathological analysis showed the presence of minimal contamination of the lung, kidney, and liver tissue samples by foreign material (titanium very likely). The analysis showed only limited pathological changes, especially in liver and kidneys, which might be attributed to the influence of
Kramer, S.; Nelson, P.
Wave energy converters (WECs) and tidal energy converters (TECs) are only beginning to be deployed along the U.S. West Coast and in Hawai'i, and a better understanding of their ecological effects on fish, particularly on special status fish is needed to facilitate project siting, design and environmental permitting. The structures of WECs and TECs placed on to the seabed, such as anchors and foundations, may function as artificial reefs that attract reef associated fishes, while the midwater and surface structures, such as mooring lines, buoys, and wave or tidal power devices, may function as fish aggregating devices (FADs). We evaluated these potential ecological interactions by comparing them to surrogate structures, such as artificial reefs, natural reefs, kelp vegetation, floating and sunken debris, oil and gas platforms, anchored FADs deployed to enhance fishing opportunities, net cages used for mariculture, and piers and marinas. We also conducted guided discussions with scientists and resource managers to provide unpublished observations. Our findings indicate the structures of WECs and TECs placed on or near the seabed in coastal waters of the U.S. West Coast and Hawai`i likely will function as small scale artificial reefs and attract potentially high densities of reef associated fishes and the midwater and surface structures of WECs placed in the tropical waters of Hawai`i likely will function as de facto FADs.
Tamura, Nozomi; Yamamoto, Takahiko; Aoki, Hirooki; Koshiji, Kohji; Homma, Akihiko; Tatsumi, Eisuke; Taenaka, Yoshiyuki
In Totally-Implantable Artificial Heart(TAH) system, Transcutaneous Optical Information Transmission System(TOITS) and Externally Coupled Transcutaneous Energy Transmission System(ECTETS) are effective for driving, controlling and monitoring the TAH. Using these systems, a patient needs to wear an optical coupler and a transcutaneous transformer separately, and then the patient's QOL (Quality of Life) will be deteriorated. In this paper, for improving the QOL, the energy and information transmission using an unified transcutaneous transformer was investigated, and their information transmission characteristics were evaluated.
Tamura, Nozomi; Yamamoto, Takahiko; Aoki, Hirooki; Koshiji, Kohji; Homma, Akihiko; Tatsumi, Eisuke; Taenaka, Yoshiyuki
In Totally-Implantable Artificial Heart (TAH) system, Transcutaneous Optical Information Transmission System (TOITS) and Externally Coupled Transcutaneous Energy Transmission System (ECTETS) are effective for driving, controlling and monitoring the TAH. Using these systems, a patient needs to wear an optical coupler and a transcutaneous transformer separately, and then the patient's QOL (Quality of Life) will be deteriorated. Therefore, we research the energy and information transmission by wearing an unified transcutaneous transformer. In this paper, the unified transcutaneous transformer for the energy and information transmission was investigated. As a result, the unified transformer, by which the coupling between the energy and information transmission was reduced, was developed.
Yamamoto, Takahiko; Koshiji, Kohji
A transcutaneous optical information transmission system (TOITS) offers the most promising method for noninvasively transmitting the information to control a total artificial heart (TAH). We had used light-emitting diode (LED) and photo diode (PD) with different wavelengths for full-duplex bidirectional communication in the TOITS. In this study, reduction of optical crosstalk in full-duplex bidirectional communication was investigated by using a combination of two orthogonal polarizers with the same wavelength. As a result, we confirmed that optical crosstalk could be prevented for communication through a cow's skin (3.5 mm thick) and that the signal waveform could be transmitted satisfactorily.
Affeld, K.; Schichl, K.; Ziemann, A.; Freydefont, M.
The blood flow separation which plays an important role in thrombosis formation is examined. A fluorescent coloring was homogeneously mixed with the water volume behind the valve in the aorta root for modeling blood platelets; a longitudinal circulating coloring cloud corresponds to a beginning of thrombosis while the water depicts the fresh blood. Coloring concentration was varied and these lightness changes were examined with a video system so that the gray values were quantified and their time dependence evaluated. The mean value was calculated and the concentration was established as an exponential function of time. The results show the thrombosis risk due to artificial heart valves.
Dang, Nicholas C; Topkara, Veli K; Mercando, Michelle; Kay, Joy; Kruger, Kurt H; Aboodi, Michael S; Oz, Mehmet C; Naka, Yoshifumi
Right heart failure (RHF) is not an infrequent complication of left ventricular assist device (LVAD) implantation. Few studies have examined outcomes for LVAD patients who subsequently develop RHF. This study details one center's experience with RHF in chronic congestive heart failure (CHF) patients. One hundred eight patients with chronic CHF (>or=6 months) who underwent HeartMate LVAD implantation were identified during June 1996 to July 2004. Acute heart failure patients requiring LVADs were excluded to eliminate the impact of confounding non-cardiac factors. RHF was defined as the need for a subsequent right ventricular assist device (RVAD), >or=14 days of intravenous inotropes/pulmonary vasodilators, or both. Forty-two (38.9%) RHF patients were identified. Fourteen of these required RVAD insertion. Outcome parameters included early (
Abraham, William T
Heart failure represents a major public health concern, associated with high rates of morbidity and mortality. A particular focus of contemporary heart failure management is reduction of hospital admission and readmission rates. While optimal medical therapy favourably impacts the natural history of the disease, devices such as cardiac resynchronization therapy devices and implantable cardioverter defibrillators have added incremental value in improving heart failure outcomes. These devices also enable remote patient monitoring via device-based diagnostics. Device-based measurement of physiological parameters, such as intrathoracic impedance and heart rate variability, provide a means to assess risk of worsening heart failure and the possibility of future hospitalization. Beyond this capability, implantable haemodynamic monitors have the potential to direct day-to-day management of heart failure patients to significantly reduce hospitalization rates. The use of a pulmonary artery pressure measurement system has been shown to significantly reduce the risk of heart failure hospitalization in a large randomized controlled study, the CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients (CHAMPION) trial. Observations from a pilot study also support the potential use of a left atrial pressure monitoring system and physician-directed patient self-management paradigm; these observations are under further investigation in the ongoing LAPTOP-HF trial. All these devices depend upon high-intensity remote monitoring for successful detection of parameter deviations and for directing and following therapy.
Sauer, I M; Frank, J; Bücherl, E S
A new type of energy converter for an electro-mechanical total artificial heart (TAH) based on the principle of a unidirectional moving motor is described. Named the TAH Serpentina, the concept consists of 2 major parts, a pendulum shaped movable element fixed on one side using a joint bearing and a special shaped drum cam. Pusher plates are mounted flexibly to the crossbar of the pendulum. A motor drives the special shaped drum cam linked to the pendulum through a ball bearing. The circular motion of the unidirectional moving brushless DC motor is transferred into the linear motion of the pendulum to drive the pusher plates. Using a crossbar with a variable length, the stroke of the pendulum and therefore the displaced blood volume is alterable. To achieve a variable length, an electric driven screw thread or a hydraulic system is possible. Comparable to the natural heart, cardiac output would be determined by frequency and stroke volume.
Müller, Boje; Noll, Gundula A; Ernst, Antonia M; Rüping, Boris; Groscurth, Sira; Twyman, Richard M; Kawchuk, Lawrence M; Prüfer, Dirk
Forisomes are mechanoproteins that undergo ATP-independent contraction-expansion cycles triggered by divalent cations, pH changes, and electrical stimuli. Although native forisomes from Medicago truncatula comprise a number of subunits encoded by separate genes, here we show that at least two of those subunits (MtSEO1 and MtSEO4) can assemble into homomeric forisome bodies that are functionally similar to their native, multimeric counterparts. We expressed these subunits in plants and yeast, resulting in the purification of large quantities of artificial forisomes with unique characteristics depending on the expression platform. These artificial forisomes were able to contract and expand in vitro like native forisomes and could respond to electrical stimulation when immobilized between interdigital transducer electrodes. These results indicate that recombinant artificial forisomes with specific characteristics can be prepared in large amounts and used as components of microscale and nanoscale devices.
Mohamed, Mohamed A; Islas, Jose F; Schwartz, Robert J; Birla, Ravi K
Development of tissue-engineered hearts for treatment of myocardial infarction or biologic pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. To further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously. In this study, we examined the effect of an intermittent biphasic square wave on our artificial heart muscle (AHM) composed of neonatal rat cardiac cells and fibrin gel. Twitch forces, spontaneous contraction rates, biopotentials, gene expression profiles, and histologic observations were examined for the ES protocol over a 12 day culture period. We demonstrate improved consistency between samples for twitch force and contraction rate, and higher normalized twitch force amplitudes for electrically stimulated AHMs. Improvements in electrophysiology within the AHM were noted by higher conduction velocities and lower latency in electrical response for electrically stimulated AHMs. Genes expressing key electrophysiologic and structural markers peaked at days 6 and 8 of culture, only a few days after the initiation of ES. These results may be used for optimization strategies to establish protocols for producing AHMs capable of replacing damaged heart tissue in either a contractile or electrophysiologic capacity. Optimized AHMs can lead to alternative treatments to heart failure and alleviate the limited donor supply crisis.
Urbaszek, W; Schmitz, K P; Emmrich, K; Klinkmann, H
The state of the technical development of the mechanical assist systems and the artificial heart, respectively, guarantees a sufficient support of the circulatory system up to the improvement of the own heart function or to the possible heart transplantation. There is the necessity for the temporarily limited support of the heart, but also for the long-term one. Independent of the underlying etiology in acute conditions of cardiac failure in many cases the external supporting system may be sufficiently helpful. The antithrombotic therapy and the prophylaxis of infections demands particular carefulness. There is still no representable release for the long-term use of the hitherto available cardiovascular supporting systems. The question is controversial, whether then an experiment on patients or an already accepted therapeutic intervention is still taken into consideration. Essential prerequisites for the long-term use would be a full implantability of the systems in transcutaneous energy transmission, a further biologization of the blood-contacting materials, a clarification of the immune phenomena, a possibly automatic mode of action adapted to the need as well as a reliable strategy of antithrombotic therapy. The increased risk of infection should be taken into consideration.
Takatani, Setsuo; Sakamoto, Tohru; Ohuchi, Katsuhiro; Nakamura, Makoto; Mizuno, Tomohiro; Arai, Hirokuni
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.
Symes, Mark D; Cogdell, Richard J; Cronin, Leroy
Artificial photosynthesis aims at capturing solar energy and using it to produce storable fuels. However, while there is reason to be optimistic that such approaches can deliver higher energy conversion efficiencies than natural photosynthetic systems, many serious challenges remain to be addressed. Perhaps chief among these is the issue of device stability. Almost all approaches to artificial photosynthesis employ easily oxidized organic molecules as light harvesters or in catalytic centres, frequently in solution with highly oxidizing species. The 'elephant in the room' in this regard is that oxidation of these organic moieties is likely to occur at least as rapidly as oxidation of water, meaning that current device performance is severely curtailed. Herein, we discuss one possible solution to this problem: using self-assembling organic-polyoxometalate hybrid structures to produce compartments inside which the individual component reactions of photosynthesis can occur without such a high incidence of deleterious side reactions.
Joya, Khurram Saleem; Joya, Yasir F; Ocakoglu, Kasim; van de Krol, Roel
The development of new energy materials that can be utilized to make renewable and clean fuels from abundant and easily accessible resources is among the most challenging and demanding tasks in science today. Solar-powered catalytic water-splitting processes can be exploited as a source of electrons and protons to make clean renewable fuels, such as hydrogen, and in the sequestration of CO2 and its conversion into low-carbon energy carriers. Recently, there have been tremendous efforts to build up a stand-alone solar-to-fuel conversion device, the "artificial leaf", using light and water as raw materials. An overview of the recent progress in electrochemical and photo-electrocatalytic water splitting devices is presented, using both molecular water oxidation complexes (WOCs) and nano-structured assemblies to develop an artificial photosynthetic system.
Cios, Theodore J.; Salamanca-Padilla, Yuliana; Guvakov, Dmitri
Patient: Male, 44 Final Diagnosis: Heparin-induced thrombocytopenia Type II Symptoms: Congestive heart failure • short of breath Medication: — Clinical Procedure: LVAD explantation • TAH insertion Specialty: Anesthesiology Objective: Rare co-existance of disease or pathology Background: Heparin-induced thrombocytopenia (HIT) is a rare but life-threatening complication of heparin administration. It can present a major clinical dilemma for physicians caring for patients requiring life-saving urgent or emergent cardiac surgery. Studies have been published examining the use of alternative anticoagulants for patients undergoing cardiopulmonary bypass (CPB), however, evidence does not clearly support any particular approach. Presently, there are no large-scale, prospective randomized studies examining the impact of alternative anticoagulants on clinical outcomes for HIT-positive patients requiring cardiac surgery. Case Report: We present the case of a patient who underwent SynCardia Total Artificial Heart (TAH) implantation following a recent left ventricular assist device (LVAD) placement. The patient was receiving argatroban for type II HIT with anuric renal failure, and developed a thrombus which occluded the inflow cannula of the LVAD. Based on a published study and after establishing consensus with the surgical, anesthesiology, perfusion, and hematology teams, we decided to use tirofiban as an antiplatelet agent to inhibit the platelet aggregation induced by heparin, and ultimately used heparin as the anticoagulant for cardiopulmonary bypass. Conclusions: When selecting anticoagulation for a HIT-positive patient requiring CPB, so that benefits outweigh risks, it is of paramount importance that the decision be based on a multitude of factors. The team caring for the patient should have a shared mental model and be familiar with the pharmacology, devices used, and local practices. These three elements should be integrated with patient-specific comorbidities
Ohgoe, Yasuharu; Takada, Satoshi; Hirakuri, Kenji K; Tsuchimoto, Katsuya; Homma, Akihiko; Miyamatsu, Toshinobu; Saitou, Tomoyuki; Friedbacher, Gernot; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Fukui, Yasuhiro
In this study, the authors used diamond-like carbon film to coat the ellipsoidal diaphragm (polyurethane elastomer) of artificial hearts. The purpose of such coatings is to prevent the penetration of hydraulic silicone oil and blood through the diaphragm. To attach diamond-like carbon film uniformly on the diaphragm, the authors developed a special electrode. In estimating the uniformity of the diamond-like carbon film, the thickness was measured using a scanning electron microscope, and the characteristics of the diamond-like carbon film was investigated using infrared spectroscopy, Ar-laser Raman spectrophotometer, and x-ray photoelectron spectrometer. Also, to estimate the penetration of silicone oil through the diaphragm, in vitro testing was operated by alternating the pressure of silicone oil for 20 days. The authors were able to successfully attach uniform deposition of diamond-like carbon film on the ellipsoidal diaphragm. In this in vitro test, diamond-like carbon film was proven to have good stability. The amount of silicone oil penetration was improved by one-third using the diamond-like carbon film coating compared with an uncoated diaphragm. It is expected that through the use of the diamond-like carbon film, the dynamic compatibility of an artificial heart diaphragm will increase.
Masuzawa, T; Taenaka, Y; Tatsumi, E; Choi, W W; Toda, K; Ohno, T; Baba, Y; Nakatani, T; Takano, H; Uyama, C
The authors have been developing an electrohydraulic total artificial heart with a basic concept placing the blood pumps and an electrohydraulic energy converter separately, in the thorax and the abdominal region, respectively, to minimize anatomic constraints. Major problems of the system were a high energy consumption of 56 W at 6 L/min output and an insufficient maximum output of 6.7 L/min. The energy converter was redesigned to overcome these problems. A three phase, 4 pole brushless DC motor, which has maximum efficiency of 79% at a motor rotation of 2500 rpm with a load of 0.1 Nm, was developed for the new energy converter. Flow-channel design of the regenerative oil pump was optimized, which resulted in increasing the maximum flow rate at one directional motor rotation from 18 to 29 L/min. In vitro performance of the electrohydraulic total artificial heart was evaluated in a mock circulation with physiologic pressure conditions. Maximum output was increased to 10.7 L/min at a pump rate of 120 bpm and energy consumption of the motor at 6 L/min output was reduced to 18 W. Based upon these favorable results, the system is now being assembled for chronic animal implantation.
Gräf, Felix; Rossbroich, Ralf; Finocchiaro, Thomas; Steinseifer, Ulrich
One of the most critical components regarding the durability of the ReinHeart total artificial heart (TAH) is its biocompatible diaphragm, which separates the drive unit from the ventricles. Hence, a durability tester was designed to investigate its required 5-year lifetime. The aim of this study was to prove the validity of accelerated testing of the polyurethane diaphragm. The durability tester allows simultaneous testing of 12 diaphragms and mimics physiological conditions. To accelerate the time of testing, it operates with an increased speed at a frequency of 8 Hz. To prove the correctness of this acceleration, a servo-hydraulic testing machine was used to study the effect of different frequencies and their corresponding loads. Thereby the viscoelastic behavior of the polyurethane was investigated. Additionally, high-speed video measurements were performed. The force against frequency and the high-speed video measurements showed constant behavior. In the range of 1-10 Hz, the maximum resulting forces varied by 3%, and the diaphragm movement was identical. Frequencies below 10 Hz allow a valid statement of the diaphragm's mechanical durability. Viscoelasticity of the polyurethane in the considered frequency-range is negligible. The accelerated durability test is applicable to polyurethane diaphragms, and the results are applicable to TAH use. The reliability of the diaphragm for a lifetime of 5 years was found to be 80% with a confidence of 62%. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Takatani, S; Noda, H; Takano, H; Akutsu, T
In order to evaluate the pump output control based on the oxygen delivery to peripheral tissues, arterial and mixed venous hemoglobin content ([Hb]) and oxygen saturation (SO2) were continuously monitored in three biventricular bypass animals (3-, 6-, and 40-day experiments) with fibrillating ventricles. The specially developed oxygen sensors were mounted in the outflow ports of the artificial hearts to measure [Hb] and SO2. One animal was exercised on the treadmill at 2.0 mile/h for 15 min with pump flows fixed to deliver oxygen of (a) above 13 cc/min/kg, (b) 10, and (c) 9. In (a), the mixed venous saturation (SvO2) dropped to approximately 25% with no increase in the blood lactate level. In (b) and (c), the SvO2 decreased to approximately 10-15% with increase in blood lactate levels from 4 to 10-30 mg/dl. Also, the recovery of the SvO2 in these groups following the termination of the exercise was slower in comparison to (a). The lower limit of the SvO2 level that would create oxygen debt situation in the peripheral tissues was approximately 25-30% for the exercise of 2.0 mile/h. The SvO2 reflects changes in respiratory status, pump output, hemoglobin level, and metabolism, and is thus a useful indicator to diagnose quickly the circulatory status as well as possibly to control the artificial heart output.
Yankell, S L; Shi, X; Emling, R C; Bock, R T
A sonic subgingival cleaning device (soniPick Sonic Interdental Plaque Remover) has recently been marketed with three bristle tips varying in size lengths and bundle diameters. The purpose of this study was to evaluate the ability of these bristle tips to remove subgingival artificial plaque deposits in a laboratory method used for toothbrushes. The laboratory method has been modified for testing the sonic device, to simulate the directions for using the product at home. The dimensions (length x bundle width) of three tips tested were: 0.007" x 0.040"; 0.007" x 0.062"; and 0.009" x 0.062". The tips used with the sonic device were placed on the tooth surface at a 20 degrees angle according to directions, and inserted 3 mm under simulated gingivae. The device was turned on and the tip was moved in a maximum 10 mm stroke for 15 seconds with the brushing machine. For control purposes, a flat, multi-tufted, ADA-accepted manual toothbrush (Oral-B P35) was also tested. The manual toothbrush was tested using the standard methods for evaluating toothbrushes, i.e., with the bristle tips placed at the gingival margin, then brushed at a 45 degrees angle at 250 g weight, using 15 mm strokes for 60 seconds. The depth of subgingival deposit removal was recorded as the maximum depth of the artificial plaque deposit removed from the pressure-sensitive paper under the simulated gingivae over anterior- or posterior-shaped teeth. In the assays conducted, the three bristle tips on the sonic device removed artificial plaque deposits under the simulated gingival at depths of 1.9-2.7 mm. The manual toothbrush had a mean subgingival cleaning depth of 0.6 mm. Differences between the three bristle tips used with the sonic device and the manual toothbrush were significant (p < 0.001 ANOVA). In this laboratory assay, all 3 bristle tips provided with the sonic cleaning device maintained access into and subsequent removal of artificial plaque from the subgingival space.
Farooqi, Kanwal M; Saeed, Omar; Zaidi, Ali; Sanz, Javier; Nielsen, James C; Hsu, Daphne T; Jorde, Ulrich P
As the population of adults with congenital heart disease continues to grow, so does the number of these patients with heart failure. Ventricular assist devices are underutilized in adults with congenital heart disease due to their complex anatomic arrangements and physiology. Advanced imaging techniques that may increase the utilization of mechanical circulatory support in this population must be explored. Three-dimensional printing offers individualized structural models that would enable pre-surgical planning of cannula and device placement in adults with congenital cardiac disease and heart failure who are candidates for such therapies. We present a review of relevant cardiac anomalies, cases in which such models could be utilized, and some background on the cost and procedure associated with this process.
Mock, Stephen; Dmochowski, Roger R; Brown, Elizabeth T; Reynolds, W Stuart; Kaufman, Melissa R; Milam, Douglas F
We report the impact of urethral risk factors on erosion rates and device survival outcomes after transcorporeal artificial urinary sphincter placement. We performed a retrospective analysis of all transcorporeal artificial urinary sphincters placed at a single institution between January 2000 and May 2014. We assessed patient demographic, comorbid diseases and surgical characteristics for risk factors considered poor for device survival. Risk factors were compared to postoperative complications requiring explantation, including cuff erosion, infection and device revision. A total of 37 transcorporeal artificial urinary sphincters were placed in 35 men. Placement was performed as a primary procedure in 21 of 37 cases (56.8%) and as salvage in the remainder. In this transcorporeal population there were 7 explantations (18.9%) due to erosion in 4 cases, cuff downsizing in 2 and infection in 1. Median followup from implantation to last followup was 8.5 months (range 0.9 to 63). Median time from artificial urinary sphincter placement to explantation was 17.3 months (range 0.9 to 63) and time specifically to transcorporeal erosion was 7.4 months (range 0.9 to 26). On univariate analysis no parameters were associated with sphincter cuff erosion but a history of an inflatable penile prosthesis was associated with a higher device explantation rate (60% vs 12.5%, p=0.04). No associations were revealed on multivariate logistic analysis. All 4 cuff erosion cases demonstrated greater than 2 urethral risk factors, including prior radiation therapy in all. The probability of cuff erosion in patients with 2 or more urethral risk factors was 1.65 times the probability of erosion in those with 0 or 1 urethral risk factor (95% CI 1.3, 2.2). The proportion of patients free of erosion at 35 months was 100% in those with 0 or 1 urethral risk factor and 64% in those with 2 or more risk factors (log rank test p=0.00). Similarly the proportion of patients free of explantation at 35 months
Hidalgo, Luis F; Shah, Keyur B; Cooke, Richard H; Tang, Daniel G; Kasirajan, Vigneshwar; Cooper, Howard A; Aronow, Wilbert S
Patients who received a total artificial heart (TAH) at Virginia Commonwealth University (VCU) between January 1, 2010 and December 31, 2011 were identified from the VCU Mechanical Circulatory Support Clinical Database. Retrospective data extraction from the medical records was performed from the time of TAH implantation until heart transplantation or death. Infections were classified as confirmed or suspected. Twenty-seven men and 5 women, mean age 49.5 years (range 24 to 68 years) received a TAH. The mean duration of TAH support was 225 days (range 1 to 1334 days). Of the 32 patients, 4 (12.5%) died and 28 (87.5 %) underwent heart transplantation. Causes of death were pneumonia (n=1), TAH malfunction (n=1), refractory cardiogenic shock (n=1), and respiratory failure (n=1). Seventy documented and 13 suspected infections developed in 25 patients (78%). The most common sources of infection were urinary tract (n=26), respiratory tract (n=18), and bloodstream (n=11). There were 5 pump infections and 2 drive line infections. The number of infections per patient ranged from 0 to 10. Sixteen different pathogens were identified; the most common were: Klebsiella pneumoniae (n=15), coagulase-negative Staphylococci (n=10), Enterococcus species (n=9) and Enterobacter species (n=8). Mortality directly attributable to infection was infrequent.
Kawaguchi, A T; Cabrol, C; Gandjbackhch, I; Pavie, A; Bors, V; Muneretto, C
To distinguish high-risk patients prior to implantation of a Jarvik-7 artificial heart as a bridge to transplantation, our 37 attempts were reviewed retrospectively. Arbitrary scores of 1 to 4 were given for nine preoperative factors on the basis of results obtained by uni- and multivariate analyses between successful cases and failed attempts; transplant rejection (scored 4: S4) or postoperative heart failure (S3) as the indication, recipient height less than 175 cm (S3), body surface area less than 1.8 m2 (S3), hyperbilirubinemia greater than 24 microM/l (S2), preoperative renal failure requiring dialysis (S2), weight less than 60 kg (S2), and age greater than 40 years (S1). All except one of the 16 patients with successful bridge had a total score of less than 4, with an average score of 1.3 in contrast to 6.6 in the 21 failed cases (p less than 0.001). Among the 17 patients who scored less than 4, 15 received transplants (specificity 90%), while only one qualified for transplantation among 20 patients who scored 4 or more (sensitivity 94%). The two unpredicted failures resulted from mediastinitis and pulmonary infarction, both attributable to postoperative management. Multiple preoperative factors in combination could have successfully predicted the outcome of mechanical support in our experience. These results underscore the importance of patient selection to achieve successful and effective use of the Jarvik-7 as a bridge to heart transplantation.
Nau, Amy C; Pintar, Christine; Arnoldussen, Aimee; Fisher, Christopher
We sought to determine whether intensive low vision rehabilitation would confer any functional improvement in a sample of blind adults using the BrainPort artificial vision device. Eighteen adults ages 28-69 yr (n=10 men and n=8 women) who had light perception only or worse vision bilaterally spent up to 6 hr per day for 1 wk undergoing structured rehabilitation interventions. The functional outcomes of object identification and word recognition were tested at baseline and after rehabilitation training. At baseline, participants were unable to complete the two functional assessments. After participation in the 1-wk training protocol, participants were able to use the BrainPort device to complete the two tasks with moderate success. Without training, participants were not able to perform above chance level using the BrainPort device. As artificial vision technologies become available, occupational therapy practitioners can play a key role in clients' success or failure in using these devices. Copyright © 2015 by the American Occupational Therapy Association, Inc.
Pintar, Christine; Arnoldussen, Aimee; Fisher, Christopher
OBJECTIVE. We sought to determine whether intensive low vision rehabilitation would confer any functional improvement in a sample of blind adults using the BrainPort artificial vision device. METHOD. Eighteen adults ages 28–69 yr (n = 10 men and n = 8 women) who had light perception only or worse vision bilaterally spent up to 6 hr per day for 1 wk undergoing structured rehabilitation interventions. The functional outcomes of object identification and word recognition were tested at baseline and after rehabilitation training. RESULTS. At baseline, participants were unable to complete the two functional assessments. After participation in the 1-wk training protocol, participants were able to use the BrainPort device to complete the two tasks with moderate success. CONCLUSION. Without training, participants were not able to perform above chance level using the BrainPort device. As artificial vision technologies become available, occupational therapy practitioners can play a key role in clients’ success or failure in using these devices. PMID:25553750
Wrobeln, Anna; Schlüter, Klaus D; Linders, Jürgen; Zähres, Manfred; Mayer, Christian; Kirsch, Michael; Ferenz, Katja B
The aim of this study was to prove whether albumin-derived perfluorocarbon-based nanoparticles (capsules) can operate as a novel artificial oxygen carrier in a rat Langendorff-heart perfusion model. Hearts perfused with capsules showed increased left ventricular pressure and rate pressure product compared to hearts perfused with pure Krebs-Henseleit (KH)-buffer. The capsules prevented the myocardium from functional fail when in their absence a noxious ischemia was observed. Capsules did not change rheological properties of KH-buffer and could repeatedly reload with oxygen. This albumin-derived perfluorocarbon-based artificial oxygen carrier preserved the function of rat hearts due to the transport of oxygen in a satisfactory manner. Because of these positive results, the functionality of the applied capsules should be verified in living animals.
Sales, Virna L; McCarthy, Patrick M
The Sunshine Heart C-Pulse (C-Pulse; Sunshine Heart Inc., Tustin, CA) device is an extra-aortic implantable counterpulsation pump designed as a non-blood contacting ambulatory heart assist device, which may provide relief from symptoms for class II-III congestive heart failure patients. It has a comparable hemodynamic augmentation to intra-aortic balloon counterpulsation devices. The C-Pulse cuff is implanted through a median sternotomy, secured around the ascending aorta, and pneumatically driven by an external system controller. Pre-clinical studies in the acute pig model, and initial temporary clinical studies in patients undergoing off-pump coronary bypass surgery have shown substantial increase in diastolic perfusion of the coronary vessels, which translated to a favorable improvement in ventricular function. A U.S. prospective multi-center trial to evaluate the safety and efficacy of the C-Pulse in class III patients with moderate heart failure is now in progress.
Lu, Bingwei; Chen, Ying; Ou, Dapeng; Chen, Hang; Diao, Liwei; Zhang, Wei; Zheng, Jun; Ma, Weiguo; Sun, Lizhong; Feng, Xue
Power supply for medical implantable devices (i.e. pacemaker) always challenges not only the surgery but also the battery technology. Here, we report a strategy for energy harvesting from the heart motion by using ultra-flexible piezoelectric device based on lead zirconate titanate (PZT) ceramics that has most excellent piezoelectricity in commercial materials, without any burden or damage to hearts. Experimental swine are selected for in vivo test with different settings, i.e. opened chest, close chest and awake from anesthesia, to simulate the scenario of application in body due to their hearts similar to human. The results show the peak-to-peak voltage can reach as high as 3 V when the ultra-flexible piezoelectric device is fixed from left ventricular apex to right ventricle. This demonstrates the possibility and feasibility of fully using the biomechanical energy from heart motion in human body for sustainably driving implantable devices. PMID:26538375
Lu, Bingwei; Chen, Ying; Ou, Dapeng; Chen, Hang; Diao, Liwei; Zhang, Wei; Zheng, Jun; Ma, Weiguo; Sun, Lizhong; Feng, Xue
Power supply for medical implantable devices (i.e. pacemaker) always challenges not only the surgery but also the battery technology. Here, we report a strategy for energy harvesting from the heart motion by using ultra-flexible piezoelectric device based on lead zirconate titanate (PZT) ceramics that has most excellent piezoelectricity in commercial materials, without any burden or damage to hearts. Experimental swine are selected for in vivo test with different settings, i.e. opened chest, close chest and awake from anesthesia, to simulate the scenario of application in body due to their hearts similar to human. The results show the peak-to-peak voltage can reach as high as 3 V when the ultra-flexible piezoelectric device is fixed from left ventricular apex to right ventricle. This demonstrates the possibility and feasibility of fully using the biomechanical energy from heart motion in human body for sustainably driving implantable devices.
Pantalos, G M; Kim, C H; Flatau, A
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.
Mulloy, Daniel P.; Bhamidipati, Castigliano M.; Stone, Matthew L.; Ailawadi, Gorav; Kron, Irving L.; Kern, John A.
Objectives Orthotopic heart transplantation is the standard of care for end-stage heart disease. Left ventricular assist device implantation offers an alternative treatment approach. Left ventricular assist device practice has changed dramatically since the 2008 Food and Drug Administration approval of the HeartMate II (Thoratec, Pleasanton, Calif), but at what societal cost? The present study examined the cost and efficacy of both treatments over time. Methods All patients who underwent either orthotopic heart transplantation (n = 9369) or placement of an implantable left ventricular assist device (n = 6414) from 2005 to 2009 in the Nationwide Inpatient Sample were selected. The trends in treatment use, mortality, and cost were analyzed. Results The incidence of orthotopic heart transplantation increased marginally within a 5-year period. In contrast, the annual left ventricular assist device implantation rates nearly tripled. In-hospital mortality from left ventricular assist device implantation decreased precipitously, from 42% to 17%. In-hospital mortality for orthotopic heart transplantation remained relatively stable (range, 3.8%–6.5%). The mean cost per patient increased for both orthotopic heart transplantation and left ventricular assist device placement (40% and 17%, respectively). With the observed increase in both device usage and cost per patient, the cumulative Left ventricular assist device cost increased 232% within 5 years (from $143 million to $479 million). By 2009, Medicare and Medicaid were the primary payers for nearly one half of all patients (orthotopic heart transplantation, 45%; left ventricular assist device, 51%). Conclusions Since Food and Drug Administration approval of the HeartMate II, mortality after left ventricular assist device implantation has decreased rapidly, yet has remained greater than that after orthotopic heart transplantation. The left ventricular assist device costs have continued to increase and have been
Tjulkins, Fjodors; Nguyen, Anh-Tuan Thai; Andreassen, Erik; Aasmundtveit, Knut; Hoivik, Nils; Hoff, Lars; Halvorsen, Per Steinar; Grymyr, Ole-Johannes; Imenes, Kristin
An accelerometer-based heart monitoring system has been developed for real-time evaluation of heart wall movement. In this paper, assembly and fabrication of an improved device is presented along with system characterization and test data from an animal experiment. The new device is smaller and has simplified the implantation procedure compared to earlier prototypes. Leakage current recordings were well below those set by the corresponding standards.
Lee, Lawrence S.; Shekar, Prem S.
Heart failure remains one of the most common causes of morbidity and mortality worldwide. The advent of mechanical circulatory support devices has allowed significant improvements in patient survival and quality of life for those with advanced or end-stage heart failure. We provide a general overview of past and current mechanical circulatory support devices encompassing options for both short- and long-term ventricular support. PMID:25559828
Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman
Since the advent of heart valve, several valve types such as mechanical and bio-prosthetic valves have been designed. Mechanical Heart Valves (MHV) are durable but suffer from thromboembolic complications that caused by shear-induced platelet activation near the valve region. Bio-prosthetic Heart Valves (BHV) are known for better hemodynamics. However, they usually have a short average life time. Realistic simulations of heart valves in combination with platelet activation models can lead to a better understanding of the potential risk of thrombus formation in such devices. In this study, an Eulerian approach is developed to calculate the platelet activation in three-dimensional simulations of flow through MHV and BHV using a parallel overset-curvilinear immersed boundary technique. A curvilinear body-fitted grid is used for the flow simulation through the anatomic aorta, while the sharp-interface immersed boundary method is used for simulation of the Left Ventricle (LV) with prescribed motion. In addition, dynamics of valves were calculated numerically using under-relaxed strong-coupling algorithm. Finally, the platelet activation results for BMV and MHV are compared with each other.
Horvath, David; Karimov, Jamshid H.; Byram, Nicole; Kuban, Barry; Golding, Leonard; Moazami, Nader; Fukamachi, Kiyotaka
The Cleveland Clinic continuous-flow total artificial heart passively regulates itself in regard to the relative performance of systemic and pulmonary pumps. The system incorporates real-time monitoring to detect any indication of incipient left or right suction as input for automatic controller response. To recognize suction, the external controller compares the waveforms of modulating speed input and power feedback. Deviations in periodic waveforms indicate sudden changes to flow impedance, which are characteristic of suction events as the pump speed is modulating. Incipient suction is indicated within three seconds of being detected in the power wave form, allowing timely controller response before mean flow is affected. This article describes the results obtained from subjecting the system to severe hemodynamic manipulation during an acute study in a calf. PMID:26102177
Flaherty, G; De Freitas, S
Cardiovascular disease is the leading cause of death in adult international travellers. Patients living with heart disease should receive specific, individualised pre-travel health advice. The purpose of this article is to provide evidence-based advice to physicians who are consulted by travellers with cardiovascular disease. Fitness-to-travel evaluation will often be conducted by the general practitioner but other medical specialists may also be consulted for advice. Patients with chronic medical conditions should purchase travel health insurance. The general pre-travel health consultation addresses food and water safety, insect and animal bite avoidance, malaria chemoprophylaxis, and travel vaccinations. Patients with devices such as cardiac pacemakers should be familiar with how these may be affected by travel. Cardiac medications may cause adverse effects in cold or hot environments, and specific precautions must be followed by anticoagulated travellers. The physician should be aware of how to access medical care abroad, and of the potential for imported tropical diseases in returned travellers.
Weiss, W J; Rosenberg, G; Snyder, A J; Pierce, W S; Pae, W E; Kuroda, H; Rawhouser, M A; Felder, G; Reibson, J D; Cleary, T J; Ford, S K; Marlotte, J A; Nazarian, R A; Hicks, D L
Total Artificial Heart (TAH) development at Penn State University and 3M Health Care has progressed from design improvements and manufacturing documentation to in vitro and in vivo testing to characterize the system's hemodynamic response and energetic performance. The TAH system is completely implantable and intended for use as an alternative to transplantation. It includes a dual pusher plate pump and rollerscrew actuator, welded electronics and battery assembly, transcutaneous energy transmission system, telemetry, and a compliance chamber. In vitro testing was conducted on a Penn State mock circulatory loop with glycerol/water solution at body temperature. Tests were performed to characterize the preload and afterload response, left atrial pressure control, and power consumption. A sensitive preload response was demonstrated with left atrial pressure safely maintained at less than 15 mm Hg for flow rates up to 7.5 L/min. Variations in aortic pressure and pulmonary vascular resistance were found to have minimal effects on the preload sensitivity and left atrial pressure control. In vivo testing of the completely implanted system in its final configuration was carried out in two acute studies using implanted temperature sensors mounted on the electronics, motor, and energy transmission coil in contact with adjacent tissue. The mean temperature at the device-tissue interface was less than 4 degrees C above core temperature.
Kirsch, Matthias E W; Nguyen, Anthony; Mastroianni, Ciro; Pozzi, Matteo; Léger, Philippe; Nicolescu, Michaela; Varnous, Shaida; Pavie, Alain; Leprince, Pascal
The SynCardia temporary total artificial heart (t-TAH) provides complete circulatory support by replacing both native cardiac ventricles and all cardiac valves. We performed a retrospective analysis of demographics, clinical characteristics and survival of patients bridged to transplantation using the SynCardia t-TAH (SynCardia Systems Inc, Tucson, AZ). From 2000 to 2010, the SynCardia t-TAH was implanted in 90 consecutive patients (80 males; mean age, 46 ± 13 years) suffering cardiogenic shock secondary to idiopathic (n = 40, 46%) or ischemic (n = 24, 27%) cardiomyopathy or other causes. Before implantation, 7 (9%) patients had cardiac arrest, 27 (33%) were on ventilator, and 18 (22%) were on extracorporeal life support. Pre-implant creatinine values were 1.7 ± 0.97 mg/dL and total bilirubin levels were 45 ± 32 μmol/L; mean duration of support was 84 ± 102 days. Thirty-five (39%) patients died while on support after a mean of 62 ± 107 days. Actuarial survival on device was 74% ± 5%, 63% ± 6%, and 47% ± 8% at 30, 60, and 180 days after implantation. While on support, 9 (10%) patients suffered stroke, 13 (14%) had mediastinitis, and 35 (39%) required surgical reexploration for bleeding, hematoma, or infection. Multivariate analysis revealed that older recipient age and preoperative mechanical ventilation were risk factors for death while on support. Fifty-five (61%) patients were transplanted after a mean of 97 ± 98 days of support. Actuarial survival rates were 78% ± 6%, 71% ± 6%, and 63% ± 8% at 1, 5, and 8 years after transplantation. The SynCardia t-TAH provided acceptable survival to transplantation rates with a remarkably low incidence of neurologic events. Posttransplant survival was similar to that of patients undergoing primary heart transplantation in France. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
Youdle, Jemma; Penn, Sarah; Maunz, Olaf; Simon, Andre
We report our first clinical use of the new Protek Duo(TM) cannula for peripheral veno-venous extra-corporeal life support (ECLS). A 53-year-old male patient underwent implantation of a total artificial heart (TAH) for biventricular failure. However, due to the development of post-operative respiratory dysfunction, the patient required ECLS for six days.
Krishnamoorthy, Arun; Felker, G Michael
Fluid removal and relief of congestion are central to treatment of acute heart failure. Diuretics have been the decongestive mainstay but their known limitations have led to the exploration of alternative strategies. This review compares diuretics with ultrafiltration and examines the recent evidence evaluating their use. Relevant recent studies are the Diuretic Optimization Strategies Evaluation trial (of diuretics) and the Cardiorenal Rescue Study in Acute Decompensated Heart Failure (of ultrafiltration). The Diuretic Optimization Strategies Evaluation study evaluated strategies of loop diuretic use during acute heart failure (continuous infusion versus intermittent bolus and high dose versus low dose). After 72 h, there was no significant difference with either comparison for the coprimary end points. Patients treated with a high-dose strategy tended to have greater diuresis and more decongestion compared with low-dose therapy, at the cost of transient changes in renal function. The Cardiorenal Rescue Study in Acute Decompensated Heart Failure study showed that in acute heart failure patients with persistent congestion and worsening renal function, ultrafiltration, as compared with a medical therapy, was associated with similar weight loss but greater increase in serum creatinine and more adverse events. Decongestion remains a major challenge in acute heart failure. Although recent studies provide useful data to guide practice, the relatively poor outcomes point to the continued need to identify better strategies for safe and effective decongestion.
Crespo, Elena; Lozano, Pablo; Blasco, Julián; Moreno-Garrido, Ignacio
Toxic effects of copper, atrazine and irgarol were evaluated on epiphytes attached to mimes (artificial devices that mimic the morphology of seagrasses) in order to check sensitivity of this biological group. Tube-dwelling diatoms were the major component of the epiphyte community. Superoxide dismutase activity was enhanced by exposure to 25 and 50 μg L(-1) of atrazine; the organism generates this antioxidant response to prevent cellular damage by removing reactive oxygen substances produced by oxidative stress. The measurement of antioxidant enzymatic activity in epiphytes could be a useful technique for ecotoxicology monitoring in marine coastal environments.
Kim, Soo Jeong; Lee, Dong Hyuk; Song, Inchang; Kim, Nam Gook; Park, Jae-Hyeung; Kim, JongHyo; Han, Man Chung; Min, Byong Goo
Phase-contrast (PC) method of magnetic resonance imaging (MRI) has bee used for quantitative measurements of flow velocity and volume flow rate. It is a noninvasive technique which provides an accurate two-dimensional velocity image. Moreover, Phase Contrast Cine magnetic resonance imaging combines the flow dependent contrast of PC-MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. However, the accuracy of the data acquired from the single through-plane velocity encoding can be reduced by the effect of flow direction, because in many practical cases flow directions are not uniform throughout the whole region of interest. In this study, we present dynamic three-dimensional velocity vector mapping method using PC-MRI which can visualize the complex flow pattern through 3D volume rendered images displayed dynamically. The direction of velocity mapping can be selected along any three orthogonal axes. By vector summation, the three maps can be combined to form a velocity vector map that determines the velocity regardless of the flow direction. At the same time, Cine method is used to observe the dynamic change of flow. We performed a phantom study to evaluate the accuracy of the suggested PC-MRI in continuous and pulsatile flow measurement. Pulsatile flow wave form is generated by the ventricular assistant device (VAD), HEMO-PULSA (Biomedlab, Seoul, Korea). We varied flow velocity, pulsatile flow wave form, and pulsing rate. The PC-MRI-derived velocities were compared with Doppler-derived results. The velocities of the two measurements showed a significant linear correlation. Dynamic three-dimensional velocity vector mapping was carried out for two cases. First, we applied to the flow analysis around the artificial heart valve in a flat phantom. We could observe the flow pattern around the valve through the 3-dimensional cine image. Next, it is applied to the complex flow inside the polymer sac that is used as ventricle in
Cuenca-Navalon, Elena; Laumen, Marco; Finocchiaro, Thomas; Steinseifer, Ulrich
A physiological control algorithm is being developed to ensure an optimal physiological interaction between the ReinHeart total artificial heart (TAH) and the circulatory system. A key factor for that is the long-term, accurate determination of the hemodynamic state of the cardiovascular system. This study presents a method to determine estimation models for predicting hemodynamic parameters (pump chamber filling and afterload) from both left and right cardiovascular circulations. The estimation models are based on linear regression models that correlate filling and afterload values with pump intrinsic parameters derived from measured values of motor current and piston position. Predictions for filling lie in average within 5% from actual values, predictions for systemic afterload (AoPmean , AoPsys ) and mean pulmonary afterload (PAPmean ) lie in average within 9% from actual values. Predictions for systolic pulmonary afterload (PAPsys ) present an average deviation of 14%. The estimation models show satisfactory prediction and confidence intervals and are thus suitable to estimate hemodynamic parameters. This method and derived estimation models are a valuable alternative to implanted sensors and are an essential step for the development of a physiological control algorithm for a fully implantable TAH.
Mussivand, T; Navarro, R; Chen, J F; Braun, J; Harasaki, H; Kiraly, R; Batur, C; McMillin, C; Nosé, Y
The purpose of the study was to characterize flow properties within a clinical pusher plate type artificial heart. Dual camera video tape and synchronized still photographs were used to study flow patterns. Diffused light and a planar laser source provided illumination. The laser light was turned into a plane of light with a thickness varying from 0.1 to 10 mm, and magnesium oxide and Amberlite particles were used as tracers. Qualitative and quantitative analyses were performed by the examination and digitization of flow patterns. Inflow, outflow, pneumatic drive and after-load pressure, diaphragm motion, cardiac output, and heart rate were measured and recorded. An electrical circuit was developed to synchronize pump diaphragm motion with captured images of flow trajectories. Trajectories were then digitized, and velocities, turbulence, and shear stresses were calculated. As the result of these experiments, disturbed, recirculating, and stagnation zones were identified and global and local turbulence values were determined. Simultaneous turbulence, stasis, recirculation, and laminar flow patterns were observed during most phases of the pumping cycle. Velocities obtained varied from 2 cm/sec to 145 cm/sec; total local shear stresses of 12 to 897 dynes/cm2 were seen.
Karimov, Jamshid H.; Moazami, Nader; Kobayashi, Mariko; Sale, Shiva; Such, Kimberly; Byram, Nicole; Sunagawa, Gengo; Horvath, David; Gao, Shengqiang; Kuban, Barry; Golding, Leonard A.; Fukamachi, Kiyotaka
Objective The Cleveland Clinic continuous-flow total artificial heart (CFTAH) is a compact, single-piece, valveless, pulsatile pump providing self-regulated hemodynamic output to left/right circulation. We evaluated chronic in vivo pump performance, physiologic and hemodynamic parameters, and biocompatibility of the CFTAH in a well-established calf model. Methods CFTAH pumps have been implanted in 17 calves total. Hemodynamics, pump performance, and device-related adverse events were evaluated during studies and at necropsy. Results In vivo experiments demonstrated good hemodynamic performance (pump flow, 7.3 ± 0.7 L/min; left atrial pressure [LAP], 16 ± 3 mm Hg; right atrial pressure [RAP], 17 ± 3 mm Hg; RAP-LAP difference, 1 ± 2 mm Hg; mean arterial pressure, 103 ± 7 mm Hg; arterial pulse pressure, 30 ± 11 mm Hg; pulmonary arterial pressure, 34 ± 5 mm Hg). The CFTAH has operated within design specifications and never failed. With ever-improving pump design, the implants have shown no chronic hemolysis. Three recent animals with the CFTAH recovered well, with no postoperative anticoagulation, during planned in vivo durations of 30, 90, and 90 days (last two were intended to be 90-day studies). All these longest-surviving cases showed good biocompatibility, with no thromboembolism in organs. Conclusions The current CFTAH has demonstrated reliable self-regulation of hemodynamic output and acceptable biocompatibility without anticoagulation throughout 90 days of chronic implantation in calves. Meeting these milestones is in accord with our strategy to achieve transfer of this unique technology to surgical practice, thus filling the urgent need for cardiac replacement devices as destination therapy. PMID:26173607
Min, B G; Kim, H C; Lee, S H; Kim, J W; Kim, J T; Kim, I Y; Kim, S W; Diegel, P D; Olsen, D B
A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless dc motor inside of a rolling-cylinder, two arc-shaped pusher-plates and two polyurethane sacs. The moving-actuator type electromechanical pump has structural advantages of small size and light weight, as compared to other reported motor-driven pumps with fixed-actuator mechanisms. The results of the mock circulation tests are reported in this paper with a cardiac output of 9 L/min at an aortic pressure of 120 mmHg and a heart rate of 120 bpm. The fulfillment of the basic control requirements of the artificial heart was also confirmed, i.e., preload sensitive and afterload insensitive cardiac output response and balanced right and left ventricular outputs.
Background Good anatomical compatibility is an important aspect in the development of cardiovascular implants. This work analyzes the interaction of the pump unit of an electrically driven pulsatile Total Artificial Heart (TAH) and the mediastinum. For an adequate compliance, both overall dimensions and alignment of inlets and outlets must be matched. Methods Cross-sectional medical image data of 27 individuals, including male and female patients suffering from end stage heart failure, was segmented and reconstructed to three dimensional (3D) surface models. Dimensions and orientations of relevant structures were identified and analyzed. The TAH surface model was virtually placed in orthotopic position and aligned with atrioventricular valves and big vessels. Additionally seven conventional cadaver studies were performed to validate different pump chamber designs based on virtual findings. Thereby 3D-coordinates were captured and introduced to the virtual environment to allow quantitative comparison between different individuals. Results Spatial parameters varied more in male patients with higher values if heart failure persists. Good correlation of the virtual analysis both to literature data and conventional cadaver studies could be shown. The full data of the 27 individuals as well as the summarized values found in literature are enclosed in the appendix. By superimposing the TAH-volume model to the anatomy, various misalignments were found and the TAH-design was adjusted. Conclusions Virtual fitting allows implant design adjustments in realistic anatomy which has not been influenced by thoracotomy. Higher numbers of relevant individuals can be reasonably investigated in the virtual environment and quantitatively correlated. Using this approach, conventional cadaver studies can be significantly reduced but not obviated, due to the unavailable haptic feedback and immobility of potentially compressed structures. PMID:23941400
Svirin, I. S.; Epishina, E. V.; Voronin, V. V.; Semenishchev, E. A.; Solodova, E. N.; Nabilskaya, N. V.
In this paper we present a method for the functional analysis of human heart based on electrocardiography (ECG) signals. The approach using the apparatus of analytical and differential geometry and correlation and regression analysis. ECG contains information on the current condition of the cardiovascular system as well as on the pathological changes in the heart. Mathematical processing of the heart rate variability allows to obtain a great set of mathematical and statistical characteristics. These characteristics of the heart rate are used when solving research problems to study physiological changes that determine functional changes of an individual. The proposed method implemented for up-to-date mobile Android and iOS based devices.
Khan, Asra; Karpawich, Peter P
Innovative, nonthoracotomy, catheter-delivered therapies have redefined the approach to and treatment of congenital heart defects. Starting in the 1960s with the creation of an opening in the atrial septum to permit effective blood mixing and improve oxygen saturation in cyanotic infants, interventional cardiac procedures continue to replace many of the time-honored surgeries that were the mainstay of repair or correction for infants and children with heart defects. Now as those children reach adulthood and still require modifications of their defects, catheter-based interventions are becoming more important. This article examines some of the more recent applications of device therapy currently available to patients with congenital heart, including heart failure, septal defects, vascular problems and heart valves. Device use in deference to surgery, risks and benefits as well as complications associated with such catheter-delivered therapies are discussed.
Rochow, Niels; Chan, Emily C; Wu, Wen-I; Selvaganapathy, Ponnambalam R; Fusch, Gerhard; Berry, Leslie; Brash, John; Chan, Anthony K; Fusch, Christoph
Respiratory insufficiency is a major cause of neonatal mortality and long-term morbidity, especially in very low birth weight infants. Today, non-invasive and mechanical ventilation are commonly accepted procedures to provide respiratory support to newborns, but they can reach their limit of efficacy. To overcome this technological plateau and further reduce mortality rates, the technology of an "artificial placenta", which is a pumpless lung assist device connected to the umbilical vessels, would serve to expand the therapeutic spectrum when mechanical ventilation becomes inadequate to treat neonates with severe respiratory insufficiency. The first attempts to create such an artificial placenta took place more than 60 years ago. However, there has been a recent renaissance of this concept, including developments of its major components like the oxygenator, vascular access via umbilical vessels, flow control, as well as methods to achieve hemocompatibility in extracorporeal circuits. This paper gives a review of past and current development, animal experiments and human case studies of artificial placenta technology.
Dunnington, Gansevoort H; Sleasman, Justin; Alkhaldi, Abdulaziz; Pelletier, Marc P; Reitz, Bruce A; Robbins, Robert C
The EXCOR Berlin Heart (Berlin Heart, Berlin, Germany) was successfully used as a pediatric left ventricular assist device as a bridge to cardiac transplantation. The pneumatically driven paracorporeal device successfully supported a 7 kg patient for 53 days until a suitable heart was obtained for transplantation.
Maher, T R; Butler, K C; Poirier, V L; Gernes, D B
The HeartMate family of implanted left ventricular assist devices (LVADs) developed by Thermo Cardiosystems, Inc. (TCI) span a time frame that goes back to the beginning of clinical use of mechanical circulatory support and will stretch well into the foreseeable future. Associated blood pump technology employed in the HeartMates range from an original pusher plate concept to the most advanced rotary pump devices. Starting initially with a pneumatic actuated pusher plate pump, clinical use of the HeartMate I began in 1986. In 1990, electric motor-actuated versions of the HeartMate I began to be used clinically. Presently, the HeartMate I has been implanted in some 2,300 patients worldwide, and this LVAD is a standard by which all others are currently measured. Following the HeartMate I is TCI's next-generation, the HeartMate II, a rotary-pump-based LVAD that uses an axial flow blood pump having blood immersed mechanical bearings. Clinical trials of the HeartMate II were initiated in 2000. The HeartMate III, representing TCI's next-generation LVAD, is structured around a centrifugal blood pump that uses a magnetically levitated rotating assembly. Compared to the HeartMate II, the HeartMate III has the potential for higher overall efficiency. The pump's operating life is not dependent on bearing wear. Given the significantly advanced LVAD technology represented by HeartMates II and III, coupled with the experience of HeartMate I, TCI is well-poised to keep its LVAD products as industry standards in the future.
Slaughter, Mark S; Rogers, Joseph G; Milano, Carmelo A; Russell, Stuart D; Conte, John V; Feldman, David; Sun, Benjamin; Tatooles, Antone J; Delgado, Reynolds M; Long, James W; Wozniak, Thomas C; Ghumman, Waqas; Farrar, David J; Frazier, O Howard
Patients with advanced heart failure have improved survival rates and quality of life when treated with implanted pulsatile-flow left ventricular assist devices as compared with medical therapy. New continuous-flow devices are smaller and may be more durable than the pulsatile-flow devices. In this randomized trial, we enrolled patients with advanced heart failure who were ineligible for transplantation, in a 2:1 ratio, to undergo implantation of a continuous-flow device (134 patients) or the currently approved pulsatile-flow device (66 patients). The primary composite end point was, at 2 years, survival free from disabling stroke and reoperation to repair or replace the device. Secondary end points included survival, frequency of adverse events, the quality of life, and functional capacity. Preoperative characteristics were similar in the two treatment groups, with a median age of 64 years (range, 26 to 81), a mean left ventricular ejection fraction of 17%, and nearly 80% of patients receiving intravenous inotropic agents. The primary composite end point was achieved in more patients with continuous-flow devices than with pulsatile-flow devices (62 of 134 [46%] vs. 7 of 66 [11%]; P<0.001; hazard ratio, 0.38; 95% confidence interval, 0.27 to 0.54; P<0.001), and patients with continuous-flow devices had superior actuarial survival rates at 2 years (58% vs. 24%, P=0.008). Adverse events and device replacements were less frequent in patients with the continuous-flow device. The quality of life and functional capacity improved significantly in both groups. Treatment with a continuous-flow left ventricular assist device in patients with advanced heart failure significantly improved the probability of survival free from stroke and device failure at 2 years as compared with a pulsatile device. Both devices significantly improved the quality of life and functional capacity. (ClinicalTrials.gov number, NCT00121485.) 2009 Massachusetts Medical Society
Miller, Jacob R; Lancaster, Timothy S; Eghtesady, Pirooz
Summary The pediatric ventricular assist device (VAD) has recently shown substantial improvements in survival as a bridge to heart transplant for patients with end-stage heart failure. Since that time, its use has become much more frequent. With increasing utilization, additional questions have arisen including patient selection, timing of VAD implantation and device selection. These challenges are amplified by the uniqueness of each patient, the recent abundance of literature surrounding VAD use, as well as the technological advancements in the devices themselves. Ideal strategies for device placement must be sought, for not only improved patient care, but for optimal resource utilization. Here, we review the most relevant literature to highlight some of the challenges facing the heart failure specialist, and any physician, who will care for a child with a VAD. PMID:25732410
Shah, Sachin P.; Mehra, Mandeep R.
The increasing adoption of left ventricular assist devices (LVADs) into clinical practice is related to a combination of engineering advances in pump technology and improvements in understanding the appropriate clinical use of these devices in the management of patients with advanced heart failure. This review intends to assist the clinician in identifying candidates for LVAD implantation, to examine long-term outcomes and provide an overview of the common complications related to use of these devices. PMID:27056652
Qureshi, Sheeraz A; Koehler, Steven M; Lin, James D; Bird, Justin; Garcia, Ryan M; Hecht, Andrew C
Cross-sectional survey. The objective of this study was to investigate the authorship, content, and quality of information available to the public on the Internet pertaining to the cervical artificial disc replacement device. The Internet is widely used by patients as an educational tool for health care information. In addition, the Internet is used as a medium for direct-to-consumer marketing. Increasing interest in cervical artificial disc replacement has led to the emergence of numerous Web sites offering information about this procedure. It is thought that patients can be influenced by information found on the Internet. A cross section of Web sites accessible to the general public was surveyed. Three commonly used search engines were used to locate 150 (50/search engine) Web sites providing information about the cervical artificial disc replacement. Each Web site was evaluated with regard to authorship and content. Fifty-three percent of the Web sites reviewed were authorized by a private physician group, 4% by an academic physician group, 13% by industry, 16% were news reports, and 14% were not otherwise categorized. Sixty-five percent of Web sites offered a mechanism for direct contact and 19% provided clear patient eligibility criteria. Benefits were expressed in 80% of Web sites, whereas associated risks were described in 35% or less. European experiences were noted in 17% of Web sites, whereas only 9% of Web sites detailed the current US experience. CONCLUSION.: The results of this study demonstrate that much of the content of the Internet-derived information pertaining to the cervical artificial disc replacement is for marketing purposes and may not represent unbiased information. Until we can confirm the content on a Web site to be accurate, patients should be cautioned when using the Internet as a source for health care information related to cervical disc replacement.
Janaswamy, Praneeth; Walters, Tomos E; Nazer, Babak; Lee, Randall J
Medical care of heart failure (HF) begins with the determination of the cause of the heart failure and diagnosing potential reversible causes (i.e., coronary heart disease, hyperthyroidism, etc.). Medical therapy includes pharmacological and nonpharmacological strategies that limit and/or reverse the signs and symptoms of HF. Initial behavior modification includes dietary sodium and fluid restriction to avoid weight gain; and encouraging physical activity when appropriate. Optimization of medical therapy is the first line of treatment that includes the use of diuretics, vasodilators (i.e., ACE inhibitors or ARBs), beta blockers, and potentially inotropic agents and anticoagulation depending on the patient's severity of heart failure and LV dysfunction. As heart failure advances despite optimized medical management, cardiac resynchronization therapy (CRT), and implantable cardioverter defibrillators (ICDs) are appropriate device therapies. The development of progressive end-stage HF, despite maximal medical therapy, necessitates the consideration of mechanical circulatory devices such as ventricular assist devices (VADs) either as a bridge to heart transplantation or as destination therapy. Despite the advances in the treatment of heart failure, there is still a large morbidity and mortality associated with HF, thus the need to develop newer strategies for the treatment of HF.
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Sharma, Vinod; Rathman, Lisa D.; Small, Roy S.; Whellan, David J.; Koehler, Jodi; Warman, Eduardo; Abraham, William T.
Background Heart failure hospitalizations (HFHs) cost the US health care system ~$20 billion annually. Identifying patients at risk of HFH to enable timely intervention and prevent expensive hospitalization remains a challenge. Implantable cardioverter defibrillators (ICDs) and cardiac resynchronization devices with defibrillation capability (CRT-Ds) collect a host of diagnostic parameters that change with HF status and collectively have the potential to signal an increasing risk of HFH. These device-collected diagnostic parameters include activity, day and night heart rate, atrial tachycardia/atrial fibrillation (AT/AF) burden, mean rate during AT/AF, percent CRT pacing, number of shocks, and intrathoracic impedance. There are thresholds for these parameters that when crossed trigger a notification, referred to as device observation, which gets noted on the device report. We investigated if these existing device observations can stratify patients at varying risk of HFH. Methods We analyzed data from 775 patients (age: 69 ± 11 year, 68% male) with CRT-D devices followed for 13 ± 5 months with adjudicated HFHs. HFH rate was computed for increasing number of device observations. Data were analyzed by both excluding and including intrathoracic impedance. HFH risk was assessed at the time of a device interrogation session, and all the data between previous and current follow-up sessions were used to determine the HFH risk for the next 30 days. Results 2276 follow-up sessions in 775 patients were evaluated with 42 HFHs in 37 patients. Percentage of evaluations that were followed by an HFH within the next 30 days increased with increasing number of device observations. Patients with 3 or more device observations were at 42× HFH risk compared to patients with no device observation. Even after excluding intrathoracic impedance, the remaining device parameters effectively stratified patients at HFH risk. Conclusion Available device observations could provide an effective
Schweiger, Martin; Stepanenko, Alexander; Potapov, Evgenji; Drews, Thorsten; Hetzer, Roland; Krabatsch, Thomas
The Paracor HeartNet, a ventricular constraint device for the treatment of heart failure (HF), is implanted through a left lateral thoracotomy. It envelopes the heart like a mesh "bag." This method of application raises the question of whether adhesions with the pericardium allow the safe implantation of a left ventricular assist device (LVAD) if HF worsens. A male patient who had undergone implantation of the Paracor HeartNet 42 months earlier presented with advanced HF for cardiac transplantation. The patient's condition deteriorated, and because no suitable organ for transplantation was available, implantation of an LVAD became necessary. Surgery was performed via a median sternotomy without complications. No severe adhesions were found. This is the first report on "how to do" LVAD implantation after Paracor HeartNet implantation with images and information about cutting the constraint. Because the Paracor HeartNet is "wrapped" around the heart, concerns persist that severe adhesions with the pericardium might occur. In this case, LVAD implantation after therapy with the Paracor HeartNet was without complications, and the expected massive adhesions were absent.
Bandorski, Dirk; Höltgen, Reinhard; Stunder, Dominik; Keuchel, Martin
According to the recommendations of the US Food and Drug Administration and manufacturers, capsule endoscopy should not be used in patients carrying implanted cardiac devices. For this review we considered studies indexed (until 30.06.2013) in Medline [keywords: capsule endoscopy, small bowel endoscopy, cardiac pacemaker, implantable cardioverter defibrillator, interference, left heart assist device], technical information from Given Imaging and one own publication (not listed in Medline). Several in vitro and in vivo studies included patients with implanted cardiac devices who underwent capsule endoscopy. No clinically relevant interference was noticed. Initial reports on interference with a simulating device were not reproduced. Furthermore technical data of PillCam (Given Imaging) demonstrate that the maximum transmission power is below the permitted limits for cardiac devices. Hence, impairment of cardiac pacemaker, defibrillator or left ventricular heart assist device function by capsule endoscopy is not expected. However, wireless telemetry can cause dysfunction of capsule endoscopy recording. Application of capsule endoscopy is feasible and safe in patients with implanted cardiac devices such as pacemakers, cardioverter defibrillators, and left heart assist devices. Development of new technologies warrants future re-evaluation. PMID:24714370
Takatani, S; Shiono, M; Sasaki, T; Glueck, J; Noon, G P; Nosé, Y; DeBakey, M E
A totally implantable, one-piece, electrome-chanical total artificial heart (TAH) intended for permanent human use has been developed. It consists of left and right pusher-plate pumps (63 cc design stroke volume) sandwiching a thin center piece with a compact electromechanical actuator. The pusher-plates are shaped conically to accommodate an actuator in the space between them. The actuator consists of an efficient and durable planetary roller screw and direct current brushless motor. The left master alternate pumping mode was implemented utilizing the left pump pusher-plate position signal. The blood-contacting surface was coated with a dry gelatin to yield long-term clot-free performance. Trileaflet tissue valves of 27 and 23 mm are used in the inflow and outflow ports. The diameter and thickness of the TAH are 97 and 82 mm. the overall volume is 510 cc, and the weight is 620 g. Anatomic fit was confirmed in 26 heart transplant recipients (body weight 78 kg and surface area 2 m2) without compressing adjacent organs. The pump performance study revealed that the TAH can yield outputs of 3-8 L/min against the 100 mm Hg afterload with 1-10 mm Hg filling pressure. The input power to the motor ranged from 7 to 12 W, with an efficiency of 18% to 14%. A one-week in vivo calf study demonstrated adequate performance of the TAH, particularly the regulation of atrial pressures. Good anatomic fit and good biocompatibility were also demonstrated.
Kiruthiga, G; Sharmila, A; Mahalakshmi, P; Muruganandam, M
Continuous measurement of heart rate is necessary for monitoring the patients with heart ailments. A wearable which continuously measures heart rate of an individual by a method called reflectance-based photoplethysmography (PPG) computes the heart rate of an individual according to the volumetric changes in blood flowing through the body is developed. In order to make the device more compact as well as with IP67 and IP68 standard, wireless charging technique is employed because it helps to get rid of wires while charging. Following the Qi standard for designing wireless power receiver circuits makes the device interoperable and work with greater efficiency with reduced losses. Impedance matching and designing the circuit to operate under resonance condition increases coupling efficiency in case of inductive coupling.
Facta, Stefania; Fusette, Stefania Saudino; Bonino, Alessandro; Anglesio, Laura; d'Amore, Giovanni
Use of ultraviolet radiation-emitting tanning devices has been classified as "carcinogenic to humans" (group 1) by the International Agency for Research on Cancer. Following this classification, the knowledge of typical ultraviolet emission levels from tanning devices can be of interest for evaluating their impact on health. In this work, the results of an extensive measurement campaign on artificial tanning appliances are presented. Ultraviolet emissions from 94 tanning appliances produced by 15 different manufacturers were characterized by onsite spectroradiometric measurements. The measured radiometric quantities were compared with reference values fixed in the European technical standard EN 60335-2-27 "Household and similar electrical appliances-Safety. Part 2: Particular requirements for appliances for skin exposure to ultraviolet and infrared radiation." Measurement results indicate that 88% of the examined appliances had ultraviolet emissions not compliant with the technical standard. Among the considered appliances, tanning devices equipped with low pressure lamps showed higher ultraviolet levels of effective irradiance and less compliance with standard requirements. In particular, UV emissions from 100% of low pressure appliances and from 78% of high pressure appliances exceeded the irradiance limit of 0.3 Wm set by the European technical standard.
Colomb, M.; Hirech, K.; André, P.; Boreux, J. J.; Lacôte, P.; Dufour, J.
Transport safety is a major goal in the European Union. Low visibility conditions, especially due to fog, increase the risk of major accidents (chain collision). Innovative products have been developed by the automotive industry, including equipment manufacturers, to increase the level of safety of car passengers and drivers. Testing of these products requires the simulation or artificial reproduction of low visibility (fog) conditions with good stability and reproducibility characteristics. We report on the results of the European Union funded "FOG" project to improve road transport safety through fog production in an experimental test chamber located at the Clermont-Ferrand laboratory for research on road safety and visibility. The project developed a prototype of a small-scale climatic chamber, an improved fog production spraying device, a laser-based visibility measurement device, a reduced scale transmissometer, and a combined indoor climate-fog production simulation software. The ability of the fog chamber to test for driver reaction was also investigated. Recent developments include a device able to produce stable visibility levels and homogeneous fog, representative of various types of natural water droplet distribution. The fog characteristics were determined and compared to natural fog. Results are presented for a selection of conditions including stabilized visibility levels for dense fog and two kinds of droplet distributions.
Di Molfetta, Arianna; Filippelli, Sergio; Ferrari, Gianfranco; Secinaro, Aurelio; Zielinski, Krystzof; Amodeo, Antonio
A 2-year-old child was implanted with an Berlin Heart EXCOR Ventricular Assist Device (Berlin Heart, Berlin, Germany) as a bridge to heart transplantation for idiopathic dilated cardiomyopathy. At postoperative day 296, a significant reduction of membrane movement was observed. The device was explanted and tested on a hydronumerical circulation simulator. Findings suggested that the integrity of the multilayered membrane had been compromised. This was confirmed by a computed tomography scan of the device. The computed tomography evidenced a detachment of the 3-layered membrane, with a thinner, convex layer on the side of the air chamber and an opposite convexity of the remaining membranes. These showed an additional air space within the layers.
Patel, Nikita M; Tao, Ze-Wei; Mohamed, Mohamed A; Hogan, Matt K; Gutierrez, Laura; Birla, Ravi K
Current therapies in left ventricular systolic dysfunction and end-stage heart failure include mechanical assist devices or transplant. The development of a tissue-engineered integrative platform would present a therapeutic option that overcomes the limitations associated with current treatment modalities. This study provides a foundation for the fabrication and preliminary viability of the acellular ventricular extracellular matrix (AVEM) model. Acellular ventricular extracellular matrix was fabricated by culturing 4 million rat neonatal cardiac cells around an excised acellular ventricular segment. Acellular ventricular extracellular matrix generated a maximum spontaneous contractile force of 388.3 μN and demonstrated a Frank-Starling relationship at varying pretensions. Histologic assessment displayed cell cohesion and adhesion within the AVEM as a result of passive cell seeding.
Rosenberg, G; Landis, D L; Phillips, W M; Stallsmith, J; Pierce, W S
These data presented here demonstrate how careful analysis of mock loop testing can lead to useful measurements for long-term calf experiments. The accuracy of the data rae primarily dependent upon a valid circulatory system analog and good experimental technique. These methods of determining arterial pressure, left atrial pressure and cardiac output have allowed us to obtain recordds of these important parameters for periods as long as 100 days in calves with total artificial heart implantation. These methods have also enabled us to automatically control the artifical heart under conditions of rest, exercise and pharmacologic treatment with the use of only one external pneumatic drive line pressure transducer.
This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2015 (Vol.44, No. 3, pp.130-135), with some modifications regarding several references published in 2015 or later.
Shiba, Kenji; Koshiji, Kohji
Transcutaneous Energy Transmission (TET) is one way of providing the energy needed to power a totally implantable artificial heart (TIAH). In the present study, an externally coupled TET system was implanted in a prototype human phantom to evaluate emission and immunity. In the emission evaluation, measurements were conducted based on CISPR Pub.11 and VDE 0871 standards, while immunity tests were based on the standards of the IEC 61000-4 series. The magnetic field of the radiated emission was measured using a loop antenna. At 0.1[MHz], we found the greatest magnetic field of 47.8 [dBμA/m], somewhat less than CISPR’s upper limit of 54 [dBμA/m]. For the conducted emission, by installing a noise filter and ferrite beads in the input section of the DC-power supply, conducted emission could be kept within the allowable limits of CISPR Pub.11 and VDE 0871. Finally, the immunity tests against radiated and conducted emission, electrostatic discharge and voltage fluctuation proved that the prototype could withstand the maximum level of disturbance. These results confirmed that the TET system implanted in a human phantom could, through modification, meet the emission and immunity standards.
Taenaka, Y; Masuzawa, T; Tatsumi, F; Anai, H; Toda, K; Akagi, H; Nakatani, T; Baba, Y; Fya, K; Wakisaka, Y
The authors have been developing an electrohydraulic (EH) artificial heart system for total implantation. This system consists of intrathoracic ventricles, an abdominally placed EH actuator, flexible silicone oil conduits, externally coupled transcutaneous energy transfer (TET) system, transcutaneous optical telemetry (TOT) system, internal battery, and internal control drive unit. Fitting was evaluated in chronic animal experiments as a pneumatic system in 11 goats weighing 55.2 +/- 4.2 kg and 3 calves of 52.3 +/- 1.2 kg. The longest survival time in calves was 111 days, and that in goats was 51 days. The assembled EH pump was implanted in two goats of 49 and 50 kg as an acute experiment, and 4.2-6.7 L/min of cardiac output was maintained. For the TET system, an internal coil 3 cm in diameter was implanted to make an arch covered by skin. Electric energy was transmitted from the external to the internal coil, and energy of about 20 W was carried through wires to an external load. The DC-to-DC efficiency of the system was 76-83% for 40 days. The TOT system with internal light emitting diodes and external photodiodes also was evaluated in a goat. Disalignment of up to 12 mm was tolerated. Although more improvement is necessary, most of the components showed characteristics desirable for a totally implantable system.
Fukamachi, Kiyotaka; Karimov, Jamshid H; Sunagawa, Gengo; Horvath, David J; Byram, Nicole; Kuban, Barry D; Dessoffy, Raymond; Sale, Shiva; Golding, Leonard A R; Moazami, Nader
The purpose of this study was to evaluate the effects of sinusoidal pump speed modulation of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) on hemodynamics and pump flow in an awake chronic calf model. The sinusoidal pump speed modulations, performed on the day of elective sacrifice, were set at ±15 and ± 25% of mean pump speed at 80 bpm in four awake calves with a CFTAH. The systemic and pulmonary arterial pulse pressures increased to 12.0 and 12.3 mmHg (±15% modulation) and to 15.9 and 15.7 mmHg (±25% modulation), respectively. The pulsatility index and surplus hemodynamic energy significantly increased, respectively, to 1.05 and 1346 ergs/cm at ±15% speed modulation and to 1.51 and 3381 ergs/cm at ±25% speed modulation. This study showed that it is feasible to generate pressure pulsatility with pump speed modulation; the platform is suitable for evaluating the physiologic impact of pulsatility and allows determination of the best speed modulations in terms of magnitude, frequency, and profiles.
Patel, Hitesh C; Rosen, Stuart D; Lindsay, Alistair; Hayward, Carl; Lyon, Alexander R; di Mario, Carlo
Neurohumoral activation, in which enhanced activity of the autonomic nervous system (ANS) is a key component, plays a pivotal role in heart failure. The neurohumoral system affects several organs and currently our knowledge of the molecular and systemic pathways involved in the neurohumoral activation is incomplete. All the methods of assessing the degree of activation of the autonomic system have limitations and they are not interchangeable. The methods considered include noradrenaline spillover, microneurography, radiotracer imaging and analysis of heart rate and blood pressure (heart rate variability, baroreceptor sensitivity, heart rate turbulence). Despite the difficulties, medications that affect the ANS have been shown to improve mortality in heart failure and the mechanism is related to attenuation of the sympathetic nervous system (SNS) and stimulation of the parasympathetic nervous system. However, limitations of compliance with medication, side effects and inadequate SNS attenuation are issues of concern with the pharmacological approach. The newer device based therapies for sympathetic modulation are showing encouraging results. As they directly influence the autonomic nervous system, more mechanistic information can be gleaned if appropriate investigations are performed at the time of the outcome trials. However, clinicians should be reminded that the ANS is an evolutionary survival mechanism and therefore there is a need to proceed with caution when trying to completely attenuate its effects. So our enthusiasm for the application of these devices in heart failure should be controlled, especially as none of the devices have trial data powered to assess effects on mortality or cardiovascular events. © 2013.
Inoue, Takafumi; Nishimura, Takashi; Murakami, Arata; Kinoshita, Osamu; Kyo, Shunei; Ono, Minoru
It is well known that heart failure can occur after a conventional Rastelli operation (using an anatomical right ventricle as a systemic ventricle) in patients with congenitally corrected transposition of the great arteries (CCTGA). At present, heart transplantation (HTx) is the only definitive therapy known to save such patients. The left ventricular assist device (LVAD) has been employed for patients presenting with acute deterioration of chronic heart failure as a bridge to transplantation when early HTx is not feasible. LVAD implantation in postoperative cases and/or in patients with dextrocardia is often difficult because of the complex anatomy. We report the case of a 26-year-old male patient with CCTGA who presented with heart failure after a conventional Rastelli operation and in whom paracorporeal LVAD implantation was undertaken for the management of right (systemic) ventricular failure. The patient recovered from the heart failure and remained on the HTx list for approximately 4 years with LVAD support.
Kniazeva, Tatiana; Hsiao, James C; Charest, Joseph L; Borenstein, Jeffrey T
One of the principal challenges in artificial lung technology has been the ability to provide levels of oxygen and carbon dioxide exchange that rival those of the natural human lung, while mitigating the deleterious interaction between blood and the surface of the synthetic gas exchange membrane. This interaction is exacerbated by the large oxygenator surface area required to achieve sufficient levels of gas transfer. In an effort to address this challenge, microfluidics-based artificial lung technologies comprising stacked microchannel networks have been explored by several groups. Here we report the design, fabrication and initial testing of a parallel plate multilayered silicone-based microfluidic construct containing ultrathin gas exchange membranes, aimed at maximizing gas transfer efficiency while minimizing membrane-blood contact area. The device comprises a branched microvascular network that provides controlled wall shear stress and uniform blood flow, and is designed to minimize blood damage, thrombosis and inflammatory responses seen in current oxygenators. Initial testing indicates that flow distribution through the multilayer structure is uniform and that the thin membrane can withstand pressures equivalent to those expected during operation. Oxygen transfer using phosphate buffered saline as the carrier fluid has also been assessed, demonstrating a sharp increase in oxygen transfer as membrane thickness is reduced, consistent with the expected values of oxygen permeance for thin silicone membranes.
Jung, Youngdo; Kwak, Jun-Hyuk; Kang, Hanmi; Kim, Wan Doo; Hur, Shin
This paper presents the development of a piezoelectric artificial cochlea (PAC) device capable of analyzing vibratory signal inputs and converting them into electrical signal outputs without an external power source by mimicking the function of human cochlea within an audible frequency range. The PAC consists of an artificial basilar membrane (ABM) part and an implantable packaged part. The packaged part provides a liquid environment through which incoming vibrations are transmitted to the membrane part. The membrane part responds to the transmitted signal, and the local area of the ABM part vibrates differently depending on its local resonant frequency. The membrane was designed to have a logarithmically varying width from 0.97 mm to 8.0 mm along the 28 mm length. By incorporating a micro-actuator in an experimental platform for the package part that mimics the function of a stapes bone in the middle ear, we created a similar experimental environment to cochlea where the human basilar membrane vibrates. The mechanical and electrical responses of fabricated PAC were measured with a laser Doppler vibrometer and a data acquisition system, and were compared with simulation results. Finally, the fabricated PAC in a biocompatible package was developed and its mechanical and electrical characteristics were measured. The experimental results shows successful frequency separation of incoming mechanical signal from micro-actuator into frequency bandwidth within the 0.4 kHz-5 kHz range.
Jung, Youngdo; Kwak, Jun-Hyuk; Kang, Hanmi; Kim, Wan Doo; Hur, Shin
This paper presents the development of a piezoelectric artificial cochlea (PAC) device capable of analyzing vibratory signal inputs and converting them into electrical signal outputs without an external power source by mimicking the function of human cochlea within an audible frequency range. The PAC consists of an artificial basilar membrane (ABM) part and an implantable packaged part. The packaged part provides a liquid environment through which incoming vibrations are transmitted to the membrane part. The membrane part responds to the transmitted signal, and the local area of the ABM part vibrates differently depending on its local resonant frequency. The membrane was designed to have a logarithmically varying width from 0.97 mm to 8.0 mm along the 28 mm length. By incorporating a micro-actuator in an experimental platform for the package part that mimics the function of a stapes bone in the middle ear, we created a similar experimental environment to cochlea where the human basilar membrane vibrates. The mechanical and electrical responses of fabricated PAC were measured with a laser Doppler vibrometer and a data acquisition system, and were compared with simulation results. Finally, the fabricated PAC in a biocompatible package was developed and its mechanical and electrical characteristics were measured. The experimental results shows successful frequency separation of incoming mechanical signal from micro-actuator into frequency bandwidth within the 0.4 kHz–5 kHz range. PMID:26263995
Bearnson, Gill B; Jacobs, Gordon B; Kirk, John; Khanwilkar, Pratap S; Nelson, Karl E; Long, James W
Improvements in implantable ventricular assist device (VAD) performance will be required to obtain patient outcomes that are comparable with those of heart transplantation. The HeartQuest VAD (WorldHeart, Oakland, CA, U.S.A.) is an advanced device, with full magnetic suspension of the rotor, designed to address specific clinical shortcomings in existing devices and to maximize margins of safety and performance for an implantable assist device. The device dimensions are 35 x 75 mm, with a total weight of 440 g. The system was designed using extensive computer modeling of device function; a total of two iterations of device prototypes were built before building the clinical version. Animal study results have been very promising, with over 30 calf studies completed. Plasma-free hemoglobin levels returned to preoperative levels, and other hematology results were in the normal ranges. Highlights include clean surfaces seen in a 116-day experiment with no anticoagulation after day 43. Feasibility clinical trials are planned to start in 2006.
Spiliopoulos, Sotirios; Guersoy, Dilek; Dimitriou, Alexandros Merkourios; Koerfer, Reiner; Tenderich, Gero
Despite downsizing, implantation technique of the 50-cm(3) SynCardia Total Artificial Heart and settings of the Companion driver remain unchanged. Owing to the absence of de-airing nipples, de-airing procedure is even more crucial and has to be performed carefully. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
Marom, Gil; Chiu, Wei-Che; Crosby, Jessica R.; DeCook, Katrina J.; Prabhakar, Saurabh; Horner, Marc; Slepian, Marvin J.; Bluestein, Danny
The SynCardia total artificial heart (TAH) is the only FDA approved device for replacing hearts in patients with congestive heart failure. It pumps blood via pneumatically driven diaphragms and controls the flow with mechanical valves. While it has been successfully implanted in more than 1,300 patients, its size precludes implantation in smaller patients. This study’s aim was to evaluate the viability of scaled-down TAHs by quantifying thrombogenic potentials from flow patterns. Simulations of systole were first conducted with stationary valves, followed by an advanced full-cardiac-cycle model with moving valves. All the models included deforming diaphragms and platelet suspension in the blood flow. Flow stress-accumulations were computed for the platelet trajectories and thrombogenic potentials were assessed. The simulations successfully captured complex flow patterns during various phases of the cardiac-cycle. Increased stress-accumulations, but within the safety margin of acceptable thrombogenicity, were found in smaller TAHs, indicating that they are clinically viable. PMID:25354999
Yamamoto, Takahiko; Koshiji, Kohji; Homma, Akihiko; Tatsumi, Eisuke; Taenaka, Yoshiyuki
Transcutaneous energy transmission (TET) that uses electromagnetic induction between the external and internal coils of a transformer is the most promising method to supply driving energy to a totally implantable artificial heart without invasion. Induction-heating (IH) cookers generate magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with the external and internal coils of the transcutaneous transformer. This will affect the performance of the TET and the artificial heart system. Hence, it is necessary to improve the magnetic field immunity of the TET system. During operation of the system, if the transcutaneous transformer is in close proximity to an IH cooker, the electric power generated by the cooker and coupled to the transformer can drive the artificial heart system. To prevent this coupling, the external coil was shielded with a conductive shield that had a slit in it. This reduces the coupling between the transformer and the magnetic field generated by the induction cooker. However, the temperature of the shield increased due to heating by eddy currents. The temperature of the shield can be reduced by separating the IH cooker and the shield.
Schwartz, Bryan G.; Ludeman, Daniel J.; Mayeda, Guy S.; Kloner, Robert A.; Economides, Christina; Burstein, Steven
Background Patients with cardiogenic shock (CS) are routinely treated with intra-aortic balloon pumps (IABPs). The utility of 2 new percutaneous left ventricular assist devices (PLVADs), the Impella and TandemHeart, is unknown. The objective of this study was to describe the use of PLVADs for patients with CS at our institution. Methods All cases involving PLVADs in patients with CS between between January 1, 2008 and June 30, 2010 at a private, tertiary referral hospital were reviewed retrospectively. Results All 76 cases were identified (50 IABP only, 7 Impella, 19 TandemHeart). Most Impella (5/7) and TandemHeart (10/19) patients were initially treated with an IABP before "upgrading" for increased hemodynamic support. All 76 devices (100%) were initiated successfully. Percutaneous revascularization was attempted in 63 patients with angiographic success in 57 (90%). The incidences of major complications were similar between groups, except bleeding occurred less frequently with the IABP. Mean ejection fraction on presentation was 30.4±16.5% and increased by a mean of 6.6±11.4% (P < 0.001). With the institutional approach of treating patients with CS initially with vasopressors and IABPs, then upgrading to an Impella or TandemHeart device for patients refractory to IABP therapy, the overall mortality rate was 40%. Conclusion The Impella and TandemHeart devices can be initiated successfully in patients with CS, are associated with high rates of angiographic success during high risk percutaneous interventions and may benefit the myocardium during myocardial infarction. Randomized trials are warranted investigating use of the Impella and TandemHeart devices in patients with CS and in patients refractory to conventional IABP therapy.
Tchantchaleishvili, Vakhtang; Luc, Jessica G Y; Haswell, Joshua; Hallian, William; Massey, H Todd
With increasing use of left ventricular assist devices (LVAD) for long-term circulatory support comes a growing need for device exchange. The conventional surgical approach for device exchanges has been a reoperative median resternotomy. Less invasive HeartMate II LVAD exchange via a non-muscle-dividing subxiphoid incision as an alternative to a left subcostal incision may reduce pain burden and facilitate recovery. From November 2006 through June 2015, 292 patients underwent HeartMate II LVAD placement, of which 30 (10.3%) required an exchange. Twenty-four (80%) LVAD exchanges were performed through a subxiphoid sternal-sparing approach, and 6 (20%) through reoperative sternotomy. Predominant indication for device exchange was suspected or confirmed pump thrombus (73.3%), followed by electromechanical pump dysfunction (16.7%). The subxiphoid approach resulted in significantly shorter median intensive care unit (7 vs 37 days, p = 0.01) and hospital stay (29 vs 107 days, p = 0.01) compared to reoperative sternotomy. Kaplan-Meier analysis showed comparable survival between the subgroups (p=0.15) as well as between the patients with device exchange and the rest of the HeartMate II LVAD patients at our institution (p = 0.12). Subxiphoid device exchange is a viable option, resulting in low operative morbidity and mortality with no adverse effect on late survival.
Sajjad, Mohammad; Butt, Tanveer; Oezalp, Faruk; Siddique, Aleem; Wrightson, Neil; Crawford, David; Pillay, Thasee; Schueler, Stephan
Left ventricular assist device (LVAD) explantation and exchange is a relatively infrequent but potentially complex procedure. Patients requiring such procedures have multisystem suboptimal physiological reserve due to end-stage heart failure and are prone to complications. Less-invasive procedures are believed to facilitate postoperative recovery and early mobilization. We describe an alternative approach to explantation and exchange of the HeartWare LVAD through left thoracotomy. Six patients (M = 4, F = 2, mean age = 49.16 years) underwent device explant/exchange or initial implant (explant = 2, exchange = 3, initial implant = 1) through left thoracotomy utilizing cardiopulmonary bypass and induced ventricular fibrillation (VF). The mean bypass time and mean VF arrest time were 82 and 3 min, respectively. A new outflow graft was anastomosed to the previous outflow graft in 3 cases of device exchange and to the descending aorta in 1 case of initial implant. One patient died in the intensive care unit due to unrelated causes (gram-negative sepsis) after device exchange. All others were discharged alive and currently remain on follow-up. The mean length of hospital stay was 40.66 days. On-pump approach through single thoracotomy incision is safe and equally suitable for device explant, exchange and initial implant. However, structural heart defects requiring surgical correction and the requirement of simultaneous right ventricular assist device are the limitations of this approach.
Small, Roy S; Whellan, David J; Boyle, Andrew; Sarkar, Shantanu; Koehler, Jodi; Warman, Eduardo N; Abraham, William T
We hypothesized that diagnostic data in implantable devices evaluated on the day of discharge from a heart failure hospitalization (HFH) can identify patients at risk for HF readmission (HFR) within 30 days. In this retrospective analysis of four studies enrolling patients with CRT devices, we identified patients with a HFH, device data on the day of discharge, and 30-day post-discharge clinical follow-up. Four diagnostic criteria were evaluated on the discharge day: (i) intrathoracic impedance>8 Ω below reference impedance; (ii) AF burden>6 h; (iii) CRT pacing<90%; and (iv) night heart rate>80 b.p.m. Patients were considered to have higher risk for HFR if ≥2 criteria were met, average risk if 1 criterion was met, and lower risk if no criteria were met. A Cox proportional hazards model was used to compare the groups. The data cohort consisted of a total of 265 HFHs in 175 patients, of which 36 (14%) were followed by HFR. On the discharge day, ≥2 criteria were met in 43 (16% of 265 HFHs), only 1 criterion was met in 92 (35%), and none of the four criteria were met in 130 HFHs (49%); HFR rates were 28, 16, and 7%, respectively. HFH with ≥2 criteria met was five times more likely to have HFR compared with HFH with no criteria met (adjusted hazard ratio 5.0; 95% confidence interval 1.9–13.5, P=0.001). Device-derived diagnostic criteria evaluated on the day of discharge identified patients at significantly higher risk of HFR. © 2013 The Authors. European Journal of Heart Failure
Trevitt, Sara; Simpson, Sue; Wood, Annette
Background: Closed-loop artificial pancreas device (APD) systems are externally worn medical devices that are being developed to enable people with type 1 diabetes to regulate their blood glucose levels in a more automated way. The innovative concept of this emerging technology is that hands-free, continuous, glycemic control can be achieved by using digital communication technology and advanced computer algorithms. Methods: A horizon scanning review of this field was conducted using online sources of intelligence to identify systems in development. The systems were classified into subtypes according to their level of automation, the hormonal and glycemic control approaches used, and their research setting. Results: Eighteen closed-loop APD systems were identified. All were being tested in clinical trials prior to potential commercialization. Six were being studied in the home setting, 5 in outpatient settings, and 7 in inpatient settings. It is estimated that 2 systems may become commercially available in the EU by the end of 2016, 1 during 2017, and 2 more in 2018. Conclusions: There are around 18 closed-loop APD systems progressing through early stages of clinical development. Only a few of these are currently in phase 3 trials and in settings that replicate real life. PMID:26589628
Kwant, P B; Finocchiaro, T; Förster, F; Reul, H; Rau, G; Morshuis, M; El Banayosi, A; Körfer, R; Schmitz-Rode, T; Steinseifer, U
The Aachen Total Artificial Heart (ACcor) has been under development at the Helmholtz Institute in Aachen over the last decade. It may serve as a bridge to transplant or as a long-term replacement of the natural heart. Based upon previous in vivo experiments with the ACcor total artificial heart, it was decided to optimize and redesign the pump unit. Smaller dimensions, passive filling and separability into three components were the three main design goals. The new design is called the MiniACcor, which is about 20% smaller than its predecessor, and weighs only 470 grams. Also its external driver/control unit was miniaturized and a new microcontroller was selected. To validate the design, it was extensively tested in laboratory mock loops. The MiniACcor was able to pump between 4.5 and 7 l/min at different pump rates against normal physiological pressures. Several requirements for the future compliance chamber and transcutaneous energy transmission (TET) system were also measured in the same mock loop. Further optimization and validation are being performed in cooperation with the Heart and Diabetes Centre North Rhine-Westphalia.
Karimov, Jamshid H; Moazami, Nader; Kobayashi, Mariko; Sale, Shiva; Such, Kimberly; Byram, Nicole; Sunagawa, Gengo; Horvath, David; Gao, Shengqiang; Kuban, Barry; Golding, Leonard A R; Fukamachi, Kiyotaka
The Cleveland Clinic continuous-flow total artificial heart (CFTAH) is a compact, single-piece, valveless, pulsatile pump providing self-regulated hemodynamic output to left/right circulation. We evaluated chronic in vivo pump performance, physiologic and hemodynamic parameters, and biocompatibility of the CFTAH in a well-established calf model. CFTAH pumps have been implanted in 17 calves total. Hemodynamic parameters, pump performance, and device-related adverse events were evaluated during studies and at necropsy. In vivo experiments demonstrated good hemodynamic performance (pump flow, 7.3 ± 0.7 L/min; left atrial pressure, 16 ± 3 mm Hg; right atrial pressure, 17 ± 3 mm Hg; right atrial pressure-left atrial pressure difference, 1 ± 2 mm Hg; mean arterial pressure, 103 ± 7 mm Hg; arterial pulse pressure, 30 ± 11 mm Hg; and pulmonary arterial pressure, 34 ± 5 mm Hg). The CFTAH has operated within design specifications and never failed. With ever-improving pump design, the implants have shown no chronic hemolysis. Three animals with recent CFTAH implantation recovered well, with no postoperative anticoagulation, during planned in vivo durations of 30, 90, and 90 days (last 2 were intended to be 90-day studies). All these longest-surviving cases showed good biocompatibility, with no thromboembolism in organs. The current CFTAH has demonstrated reliable self-regulation of hemodynamic output and acceptable biocompatibility without anticoagulation throughout 90 days of chronic implantation in calves. Meeting these milestones is in accord with our strategy to achieve transfer of this unique technology to human surgical practice, thus filling the urgent need for cardiac replacement devices as destination therapy. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
Yamakawa, Michael; Kyo, Shunei; Yamakawa, Sean; Ono, Minoru; Kinugawa, Koichiro; Nishimura, Takashi
Heart failure continues to be a growing health problem, eluding large-scale improvement and treatment. Cardiac transplantation has been the gold standard treatment with high post-transplant survival rates and relatively good quality of life. However, there has been an extreme shortage of organ donations, limiting transplants to only a very small portion of patients with the condition. This led to a growing interest in alternative options for the increasing population of patients who are waitlisted or ineligible for transplantation. In recent years, ventricular assist device (VAD) technologies have advanced from pulsatile blood pumps to continuous-flow pumps that have demonstrated unprecedented post-implantation survival rates. The HeartMate II, the only commercially available, continuous flow left ventricular assist device (LVAD) in the United States and Europe, has been implanted in over 10,000 patients worldwide, setting a benchmark for biomedical modalities of advanced heart failure treatment. Thanks to the successes of contemporary LVADs, patients are able to enjoy a better lifestyle, with a significantly prolonged life span and the ability to regularly partake in physical activities. In this new biomedical generation, the usage of LVADs has begun to expand towards the treatment for a wider range of heart conditions, including earlier stages of heart failure. In fact, LVAD implantations have surpassed the number of transplants taken place annually. An increasing number of patients are considering the permanent, circulatory support with an LVAD, namely destination therapy, as a promising option for treating heart failure.
Quader, Mohammed; Rusina, Zane; Lewis, Neil P; Martin, Lisa; Katlaps, Gundars
We report here a hemophilia patient who was bridged with a left ventricle assist device and later received heart transplantation. Preparation for surgery with factor VIII supplementation, intraoperative conduct of surgery, and challenges of postoperative course are described with a brief literature review.
Ahn, J M; Lee, J H; Choi, S W; Kim, W E; Omn, K S; Park, S K; Kim, W G; Roh, J R; Min, B G
The moving actuator type total artificial heart (TAH) developed in the Seoul National University has numerous design improvements based upon the digital signal processor (DSP). These improvements include the implantability of all electronics, an automatic control algorithm, and extension of the battery run-time in connection with an amorphous silicon solar system (SS). The implantable electronics consist of the motor drive, main processor, intelligent Li ion battery management (LIBM) based upon the DSP, telemetry system, and transcutaneous energy transmission (TET) system. Major changes in the implantable electronics include decreasing the temperature rise by over 21 degrees C on the motor drive, volume reduction (40 x 55 x 33 mm, 7 cell assembly) of the battery pack using a Li ion (3.6 V/cell, 900 mA.h), and improvement of the battery run-time (over 40 min) while providing the cardiac output (CO) of 5 L/min at 100 mm Hg afterload when the external battery for testing is connected with the SS (2.5 W, 192.192, 1 kg) for the external battery recharge or the partial TAH drive. The phase locked loop (PLL) based telemetry system was implemented to improve stability and the error correction DSP algorithm programmed to achieve high accuracy. A field focused light emitting diode (LED) was used to obtain low light scattering along the propagation path, similar to the optical property of the laser and miniature sized, mounted on the pancake type TET coils. The TET operating resonance frequency was self tuned in a range of 360 to 410 kHz to provide enough power even at high afterloads. An automatic cardiac output regulation algorithm was developed based on interventricular pressure analysis and carried out in several animal experiments successfully. All electronics have been evaluated in vitro and in vivo and prepared for implantation of the TAH. Substantial progress has been made in designing a completely implantable TAH at the preclinical stage.
Takatani, S; Shiono, M; Sasaki, T; Orime, Y; Sakuma, I; Noon, G; Nosé, Y; DeBakey, M
Left master alternate (LMA) ejection control based on the left pump fill method was implemented for a one-piece electromechanical total artificial heart (TAH). The TAH consists of left and right pusher-plate-type blood pumps sandwiching a compact electromechanical actuator comprising a direct current (DC) brushless motor and a planetary roller screw. The motor rotation is controlled on the basis of the roller-screw position as detected by a Hall effect sensor and a commutation pulse counting method. Since the pusher-plate shaft and roller screw are decoupled during filling, both pumps fill passively with the right and left atrial pressure. To obtain response to the right atrial pressure change in the LMA mode, the left fill trigger level as detected by a Hall effect position sensor is adjusted to operate the pump at a higher rate and to drive the right pump at 85-90% of the full stroke level. The in vitro evaluation demonstrated that this method can respond to right atrial pressure changes provided that the right pump is operated at less than the full stroke level. When the preload is high and the right pump goes into full stroke operation, the left eject level can be decreased to run the pump at a higher rate and to transfer more blood from the right to the left. In the in vivo evaluation, which lasted 1 week in a 95 kg calf, the left and right atrial pressures were kept within physiological ranges.(ABSTRACT TRUNCATED AT 250 WORDS)
Tsujimura, Shinichi; Yamagishi, Hiroto; Sankai, Yoshiyuki
In order to minimize infection risks of patients with artificial hearts, wireless data transmission methods with electromagnetic induction or light have been developed. However, these methods tend to become difficult to transmit data if the external data transmission unit moves from its proper position. To resolve this serious problem, the purpose of this study is to develop a prototype wireless data communication system with ultra high frequency radio wave and confirm its performance. Due to its high-speed communication rate, low power consumption, high tolerance to electromagnetic disturbances, and secure wireless communication, we adopted Bluetooth radio wave technology for our system. The system consists of an internal data transmission unit and an external data transmission unit (53 by 64 by 16 mm, each), and each has a Bluetooth module (radio field intensity: 4 dBm, receiver sensitivity: -80 dBm). The internal unit also has a micro controller with an 8-channel 10-bit A/D converter, and the external unit also has a RS-232C converter. We experimented with the internal unit implanted into pig meat, and carried out data transmission tests to evaluate the performance of this system in tissue thickness of up to 3 mm. As a result, data transfer speeds of about 20 kbps were achieved within the communication distance of 10 m. In conclusion, we confirmed that the system can wirelessly transmit the data from the inside of the body to the outside, and it promises to resolve unstable data transmission due to accidental movements of an external data transmission unit.
Weber, Stephan; Doi, Kazuyoshi; Massiello, Alex L; Byerman, Bryan P; Takagaki, Masami; Fukamachi, Kiyotaka; Donahue, Arthur; Chapman, Peter; Hirschman, Gordon; Vitale, Nicolas; Smith, William A
The purpose of this study was to evaluate the in vitro responses to preload and afterload of our total artificial heart (TAH), the MagScrew TAH. The TAH consists of two blood pumps and a control logic, developed at the Cleveland Clinic, OH, and the MagScrew actuator and its electronic control system, developed by Foster-Miller Technologies, Inc., Albany, NY. Tests were performed on a mock circulatory loop, using water as a test fluid. Preload sensitivity of the Mag-Screw TAH demonstrated a Frank-Starling response to preload in automatic mode. A peak flow of 10 L/min was obtained, with a left atrial pressure of 13 mm Hg. The relationship between right atrial pressure and left atrial pressure was well balanced when tested with a left bronchial shunt flow of 5% and a range of pulmonary artery and aortic pressures. With respect to afterload response, the left pump showed a relatively low sensitivity, which allowed the pump to maintain perfusion over a wide range of aortic pressures. The right pump, on the other hand, was much more sensitive to pulmonary artery pressure, which provided a measure of protection against pulmonary congestion. The very effective physiologic response of the MagScrew TAH is believed to result from employment of a left master, alternating ejection control logic, high inherent sensitivity of the blood pumps to atrial pressure, a lower effective stroke volume for the right pump, and a scaling of right side motor ejection voltage to 80% of that used for the left side ejection.
Fu, Yang; Hu, Liang; Ruan, Xiaodong; Fu, Xin
This article presents a coil-coupling-based transcutaneous energy transmission system (TETS) for wirelessly powering an implanted artificial heart. Keeping high efficiency is especially important for TETS, which is usually difficult due to transmission impedance changes in practice, which are commonly caused by power requirement variation for different body movements and coil-couple malposition accompanying skin peristalsis. The TETS introduced in this article is designed based on a class-E power amplifier (E-PA), of which efficiency is over 95% when its load is kept in a certain range. A resonance matching and impedance compressing functions coupled network based on parallel-series capacitors is proposed in the design, to enhance the energy transmission efficiency and capacity of the coil-couple through resonating, and meanwhile compress the changing range of the transmission impedance to meet the load requirements of the E-PA and thus keep the high efficiency of TETS. An analytical model of the designed TETS is built to analyze the effect of the network and also provide bases for following parameters determination. Then, according algorithms are provided to determine the optimal parameters required in the TETS for good performance both in resonance matching and impedance compressing. The design is tested by a series of experiments, which validate that the TETS can transmit a wide range of power with a total efficiency of at least 70% and commonly beyond 80%, even when the coil-couple is seriously malpositioned. The design methodology proposed in this article can be applied to any existing TETS based on E-PA to improve their performance in actual applications.
Cilingiroglu, Mehmet; Rollefson, William A; Mego, David
Congestive heart failure (CHF) secondary to ischemic cardiomyopathy is associated with significant morbidity and mortality despite currently available medical therapy. The Parachute(TM) device is a novel left ventricular partitioning device that is delivered percutaneously in the left ventricle (LV) in patients with anteroapical regional wall motion abnormalities, dilated LV and systolic dysfunction after anterior myocardial infarction with favorable clinical and LV hemodynamic improvements post-implantation. Here, we do review the current literature and present a case of the Parachute device implantation. Copyright © 2013 Elsevier Inc. All rights reserved.
Braga, Lays Magalhães; Prado, Gustavo Faibischew; Umeda, Iracema Ioco Kikuchi; Kawauchi, Tatiana Satie; Taboada, Adriana Marques Fróes; Azevedo, Raymundo Soares; Pereira Filho, Horacio Gomes; Grupi, César José; Souza, Hayala Cristina Cavenague; Moreira, Dalmo Antônio Ribeiro; Nakagawa, Naomi Kondo
Heart rate variability (HRV) analysis is a useful method to assess abnormal functioning in the autonomic nervous system and to predict cardiac events in patients with heart failure (HF). HRV measurements with heart rate monitors have been validated with an electrocardiograph in healthy subjects but not in patients with HF. We explored the reproducibility of HRV in two consecutive six-minute walk tests (6MW), 60-minute apart, using a heart rate monitor (PolarS810i) and a portable electrocardiograph (called Holter) in 50 HF patients (mean age 59 years, NYHA II, left ventricular ejection fraction ~35%). The reproducibility for each device was analysed using a paired t-test or the Wilcoxon signed-rank test. Additionally, we assessed the agreement between the two devices based on the HRV indices at rest, during the 6MW and during recovery using concordance correlation coefficients (CCC), 95% confidence intervals and Bland-Altman plots. The test-retest for the HRV analyses was reproducible using Holter and PolarS810i at rest but not during recovery. In the second 6MW, patients showed significant increases in rMSSD and walking distance. The PolarS810i measurements had remarkably high concordance correlation [0.86
Braga, Lays Magalhães; Prado, Gustavo Faibischew; Umeda, Iracema Ioco Kikuchi; Kawauchi, Tatiana Satie; Taboada, Adriana Marques Fróes; Azevedo, Raymundo Soares; Pereira Filho, Horacio Gomes; Grupi, César José; Souza, Hayala Cristina Cavenague; Moreira, Dalmo Antônio Ribeiro
Heart rate variability (HRV) analysis is a useful method to assess abnormal functioning in the autonomic nervous system and to predict cardiac events in patients with heart failure (HF). HRV measurements with heart rate monitors have been validated with an electrocardiograph in healthy subjects but not in patients with HF. We explored the reproducibility of HRV in two consecutive six-minute walk tests (6MW), 60-minute apart, using a heart rate monitor (PolarS810i) and a portable electrocardiograph (called Holter) in 50 HF patients (mean age 59 years, NYHA II, left ventricular ejection fraction ~35%). The reproducibility for each device was analysed using a paired t-test or the Wilcoxon signed-rank test. Additionally, we assessed the agreement between the two devices based on the HRV indices at rest, during the 6MW and during recovery using concordance correlation coefficients (CCC), 95% confidence intervals and Bland-Altman plots. The test-retest for the HRV analyses was reproducible using Holter and PolarS810i at rest but not during recovery. In the second 6MW, patients showed significant increases in rMSSD and walking distance. The PolarS810i measurements had remarkably high concordance correlation [0.86
Keon, W J
Heart disease remains one of the leading causes of death in the western world. In the 35 years since the first human heart transplants, cardiac transplantation has become established as the therapeutic option of choice in the management of terminal cardiac failure. Since 1981, the introduction of cyclosporin for immunosuppression has dramatically increased cardiac transplantation. However, several obstacles limit further utilization, including limited availability of donor hearts, limited ischemic time tolerated by donor hearts, and chronic rejection. Research is underway into donor heart preservation and new immunosuppressant drugs in an effort to increase donor organ availability. Due to these constraints, alternative therapies are under development. More than 2,000 circulatory assist devices have been implanted with >25% used as a bridge to heart transplantation. The University of Ottawa Heart Institute began the first Canadian implantation of circulatory assist devices in 1986 and has implanted 23 total artificial hearts and 23 ventricular assist devices. The Heart Institute is also developing a totally implantable electrohydraulic ventricular assist device (EVAD) for long-term mechanical support outside the hospital. Another alternative being evaluated for clinical use is xenotransplantation. The major obstacle for widespread use of clinical xenotransplantation remains graft rejection, and fundamental research is ongoing to address hyperacute and delayed xenograft rejection. While cardiac transplantation is the most effective treatment of terminal heart failure, limited donor hearts compel us to rely on alternatives. In the future, the research underway on xenotransplantation and mechanical circulatory assist devices will provide new options for the clinical treatment of terminal cardiac failure.
Ravi, Yazhini; Bansal, Shelley; Rosas, Paola C; Mazzaferri, Ernest L; Sai-Sudhakar, Chittoor B
Chronic heart failure is the leading cause of death in the world. With newer therapies, the burden of this disease has decreased; however, a significant number of patients remain refractive to existing therapies. Myocardial infarction often leads to ventricular remodeling and eventually contributes to heart failure. The Parachute™ (Cardiokinetix, Menlo Park, CA) is the first device designed for percutaneous ventricular restoration therapy, which reduces left ventricular volume and minimizes the risk of open surgical procedures. For the first time, we report a case of explantation of the Parachute ventricular partitioning device and transition to a HeartMate II™ left ventricular assist device and the surgical considerations for a successful outcome.
Bansal, Shelley; Rosas, Paola C.; Mazzaferri, Ernest L.; Sai-Sudhakar, Chittoor B.
Chronic heart failure is the leading cause of death in the world. With newer therapies, the burden of this disease has decreased; however, a significant number of patients remain refractive to existing therapies. Myocardial infarction often leads to ventricular remodeling and eventually contributes to heart failure. The Parachute™ (Cardiokinetix, Menlo Park, CA) is the first device designed for percutaneous ventricular restoration therapy, which reduces left ventricular volume and minimizes the risk of open surgical procedures. For the first time, we report a case of explantation of the Parachute ventricular partitioning device and transition to a HeartMate II™ left ventricular assist device and the surgical considerations for a successful outcome. PMID:27034560
... you are missing an arm or leg, an artificial limb can sometimes replace it. The device, which is ... activities such as walking, eating, or dressing. Some artificial limbs let you function nearly as well as before.
Ujeyl, A; Krüger, M
The use of left ventricular assist devices (LVAD) as a treatment for severe heart failure has gained momentum in recent years. Even at this stage the number of worldwide LVAD implantations far exceeds the volume of heart transplantations in view of the chronic shortage of donor organs. Third generation continuous flow assist devices have helped to improve survival, quality of life and symptom burden of heart failure patients in comparison to a regimen of optimal medication management. Alongside bridging to transplantation, destination therapy has become an established strategy of LVAD implantation. A careful patient selection process is crucial for a good clinical outcome after device implantation and risk assessment for postoperative right ventricular failure is of particular importance in this context. The rate of hospitalization during LVAD support is still high, despite the step-wise attempts to widen the indications to less severely ill heart failure patients. An effective perioperative and postoperative management will help to lower the incidence of complications (e.g. bleeding, infections, thromboembolic events and right ventricular failure) and to improve the encouraging results of mechanical circulatory support.
Frazier, O H
In December 2013, we performed our 1000th ventricular assist device implantation at the Texas Heart Institute. In my professional career, I have been fortunate to see the development of numerous mechanical circulatory support devices for the treatment of patients with advanced heart failure. In fact, most of the cardiac pumps in wide use today were developed in the Texas Heart Institute research laboratories in cooperation with the National Heart, Lung and Blood Institute or device innovators and manufacturers and implanted clinically at our partner St. Luke's Episcopal Hospital. My early involvement in this field was guided by my mentors, Dr Michael E. DeBakey and, especially, Dr Denton A. Cooley. Also, many of the advances are directly attributable to my ongoing clinical experience. What I learned daily in my surgical practice allowed me to bring insights to the development of this technology that a laboratory researcher alone might not have had. Young academic surgeons interested in this field might be well served to be active not only in laboratory research but also in clinical practice.
Grosek, Stefan; Mlakar, Gorazd; Vidmar, Ivan; Ihan, Alojz; Primozic, Janez
To evaluate the effect of interhospital air and ground transportation of artificially ventilated neonates on heart rate and peripheral blood leukocyte counts. Prospective, observational study. Level III multidisciplinary Neonatal and Pediatric Intensive Care Unit. Fifty-eight near-term artificially ventilated transported neonates between May 2006 and April 2007. Day-helicopter, day- and night-ground transportation. Heart rate at retrieval, on admission to the ICU and 1 h later, and peripheral blood leukocyte counts on admission and 1 d later were compared. Fifteen neonates were transported by helicopter during the daytime (D-HEL), 20 by daytime ground and 23 by nighttime ground transportation (D-GROUND, N-GROUND). No differences in delivery mode, birth weight, gestational age, gender, primary diagnoses for transportation, response time and duration of transportation were found between the groups. Similarly, no differences in pH, pCO(2), blood pressure and skin temperature at retrieval and on admission to the ICU were found between the three groups. The mean heart rate at retrieval did not differ significantly, while on arrival in the ICU and 1 h later the D-GROUND group of patients showed a significantly higher mean heart rate compared to the D-HEL and N-GROUND groups. Moreover, leukocyte counts on arrival in the ICU showed significantly higher leukocyte counts in the D-GROUND group of patients compared to the D-HEL group of patients. These results demonstrate that there is an association between daytime ground transportation and higher heart rate and peripheral blood leukocytes.
Flores, Dora-Luz; Gómez, Claudia; Cervantes, David; Abaroa, Alberto; Castro, Carlos; Castañeda-Martínez, Rubén A
Multi-layer perceptron artificial neural networks (MLP-ANNs) were used to predict the concentration of digoxin needed to obtain a cardio-activity of specific biophysical parameters in Tivela stultorum hearts. The inputs of the neural networks were the minimum and maximum values of heart contraction force, the time of ventricular filling, the volume used for dilution, heart rate and weight, volume, length and width of the heart, while the output was the digoxin concentration in dilution necessary to obtain a desired physiological response. ANNs were trained, validated and tested with the dataset of the in vivo experiment results. To select the optimal network, predictions for all the dataset for each configuration of ANNs were made, a maximum 5% relative error for the digoxin concentration was set and the diagnostic accuracy of the predictions made was evaluated. The double-layer perceptron had a barely higher performance than the single-layer perceptron; therefore, both had a good predictive ability. The double-layer perceptron was able to obtain the most accurate predictions of digoxin concentration required in the hearts of T. stultorum using MLP-ANNs.
Oshikawa, M; Araki, K; Nakamura, K; Anai, H; Onitsuka, T
Our novel control strategy for a continuous flow artificial heart by detecting the total assist and sucking points based on pump pulsatility was evaluated in acute animal experiments using beagle dogs and our mixed flow pump. The pump was installed as a left ventricular (LV) bypass through a left thoracotomy. To change LV contractility, the left coronary arteries were occluded for 30 min, followed by a 120 min reperfusion. To change LV end diastolic pressure (LVEDP), dextran solution was rapidly infused. To estimate the pump pulsatility without any specific sensor, we calculated the index of current amplitude (ICA), which was obtained from the amplitude of the motor current waveform divided by the simultaneous mean value. To investigate the basic characteristics of the ICA, the pump speed was changed temporarily from 2,300 rpm to 5,000 rpm. In 92% of all measurements, the ICA plotted against the pump speed had a peak point (t-point) that corresponded highly with the turning point from partial to total assistance. The ICA also had a trough (s-point) that corresponded with the beginning of severe sucking in most cases. Only preload significantly influenced pump flow rate at the t-point from among preload (LVEDP), afterload (SAoP), and contractility (max LV dP/dt), by which we can simulate Starling's law of the natural heart. We concluded that a continuous flow artificial heart could be well controlled by detecting the t-point and s-point.
Small, Roy S; Whellan, David J; Boyle, Andrew; Sarkar, Shantanu; Koehler, Jodi; Warman, Eduardo N; Abraham, William T
Aims We hypothesized that diagnostic data in implantable devices evaluated on the day of discharge from a heart failure hospitalization (HFH) can identify patients at risk for HF readmission (HFR) within 30 days. Methods and results In this retrospective analysis of four studies enrolling patients with CRT devices, we identified patients with a HFH, device data on the day of discharge, and 30-day post-discharge clinical follow-up. Four diagnostic criteria were evaluated on the discharge day: (i) intrathoracic impedance >8 Ω below reference impedance; (ii) AF burden >6 h; (iii) CRT pacing <90%; and (iv) night heart rate >80 b.p.m. Patients were considered to have higher risk for HFR if ≥2 criteria were met, average risk if 1 criterion was met, and lower risk if no criteria were met. A Cox proportional hazards model was used to compare the groups. The data cohort consisted of a total of 265 HFHs in 175 patients, of which 36 (14%) were followed by HFR. On the discharge day, ≥2 criteria were met in 43 (16% of 265 HFHs), only 1 criterion was met in 92 (35%), and none of the four criteria were met in 130 HFHs (49%); HFR rates were 28, 16, and 7%, respectively. HFH with ≥2 criteria met was five times more likely to have HFR compared with HFH with no criteria met (adjusted hazard ratio 5.0; 95% confidence interval 1.9–13.5, P = 0.001). Conclusion Device-derived diagnostic criteria evaluated on the day of discharge identified patients at significantly higher risk of HFR. PMID:24464745
Dening, Kirstin; Heepe, Lars; Afferrante, Luciano; Carbone, Giuseppe; Gorb, Stanislav N.
There is an increasing demand for materials that incorporate advanced adhesion properties, such as an ability to adhere in a reversible and controllable manner. In biological systems, these features are known from adhesive pads of the tree frog, Litoria caerulea, and the bush-cricket, Tettigonia viridissima. These species have convergently developed soft, hemispherically shaped pads that might be able to control their adhesion through active changing the curvature of the pad. Inspired by these biological systems, an artificial model system is developed here. It consists of an inflatable membrane clamped to the metallic cylinder and filled with air. Pull-off force measurements of the membrane surface were conducted in contact with the membrane at five different radii of curvature r c with (1) a smooth polyvinylsiloxane membrane and (2) mushroom-shaped adhesive microstructured membrane made of the same polymer. The hypothesis that an increased internal pressure, acting on the membrane, reduces the radius of the membrane curvature, resulting in turn in a lower pull-off force, is verified. Such an active control of adhesion, inspired by biological models, will lead to the development of industrial pick-and-drop devices with controllable adhesive properties.
Yuji, Jun-ichiro; Tanimura, Kaito
In this paper, we reports on a tactile sensor with Hall effect elements, which are generally used as magnetic sensors, for multimodal sensing devices to detect the contact force and the temperature. This tactile sensor consists of Hall elements and a magnet that are embedded in an elastic silicone rubber as the artificial skin. Here, the normal contact force is detected by distance change between a Hall element and a magnet, and the temperature is also detected using the temperature dependence of the Hall element. The temperature dependence of Hall elements depends on the Hall material and the drive circuit to generate the Hall voltage. In this study, two Indium antimonide (InSb) Hall elements and two drive circuits, that is, a constant voltage drive and a constant current drive were used to demonstrate the tactile sensor. Two output Hall voltages were measured in the normal contact force range from 0 to 50N, the temperature range from -10 to 50°C. The inverse response surface to identify the normal contact force and the temperature was formulated using the experimental results. It was possible to detect the contact force and the temperature by obtaining two kinds of Hall voltages.
Rosa-Diez, Guillermo; Gadano, Adrián
Chronic liver diseases affect 10% of the world population. Five million people per year have acute liver failure in occidental countries. Since more than 30 years now, orthotopic liver transplantation has been the treatment of choice for selected patients with these diseases, but the lack of enough organs to satisfy the increasing need oftransplantations as well as the elevated mortality of the operation in patients in critical condition, has led to search for additional therapies. Within the last years several therapies aiming to support liver function have developed in order to serve as a bridge to liver transplantation or as replace therapy allowing regeneration of the injured live. Biological and non biological devices providing liver support have been developed. The aim of this review is to analyze the technical aspects and the potential indications of the artificial non biological systems of liver support. In order to provide an adequate extracorporeal liver replacement, more complex and advanced techniques are needed, combining diffusion facilitated hemodialysis with adsorption and/or pheresis. Among these therapies, the more developed techniques are Single Pass Albumin Dialysis (SPAD), Molecular Adsorption Recirculating System (MARS) and the recently developed extracorporeal liver support combining albumin pheresis and fractioned adsorption (Prometheus).
Kamouh, Abdallah; John, Ranjit; Eckman, Peter
In the last few years, left ventricular assist devices (LVADs) have moved to the forefront in the management of patients with advanced heart failure. Pumps have gradually become smaller and more efficient and have clearly demonstrated survival benefits and improvement in functional status and quality of life in patients with advanced heart failure. Despite impressive advances in device technology, risk of severe complications remains, such as device thrombosis. A 62-year-old man who underwent HeartWare LVAD implantation as a bridge to cardiac transplant was admitted 18 days after device implantation with severe shortness of breath, fatigue and lethargy; he was found to have increased pump flows with high power demands and evidence of cardiogenic shock. An echocardiogram showed an echo density at the inflow cannula that was suggestive of thrombosis. Laboratory data showed evidence of hemolysis. He was treated successfully with intraventricular tissue plasminogen activator with rapid resolution of his symptoms and return of LVAD flow and power consumption to baseline. The patient was discharged with no complications or recurrence of thrombosis and received a successful transplant 1 month later.
Li, Huixia; Luo, Miyang; Zheng, Jianfei; Luo, Jiayou; Zeng, Rong; Feng, Na; Du, Qiyun; Fang, Junqun
Abstract An artificial neural network (ANN) model was developed to predict the risks of congenital heart disease (CHD) in pregnant women. This hospital-based case-control study involved 119 CHD cases and 239 controls all recruited from birth defect surveillance hospitals in Hunan Province between July 2013 and June 2014. All subjects were interviewed face-to-face to fill in a questionnaire that covered 36 CHD-related variables. The 358 subjects were randomly divided into a training set and a testing set at the ratio of 85:15. The training set was used to identify the significant predictors of CHD by univariate logistic regression analyses and develop a standard feed-forward back-propagation neural network (BPNN) model for the prediction of CHD. The testing set was used to test and evaluate the performance of the ANN model. Univariate logistic regression analyses were performed on SPSS 18.0. The ANN models were developed on Matlab 7.1. The univariate logistic regression identified 15 predictors that were significantly associated with CHD, including education level (odds ratio = 0.55), gravidity (1.95), parity (2.01), history of abnormal reproduction (2.49), family history of CHD (5.23), maternal chronic disease (4.19), maternal upper respiratory tract infection (2.08), environmental pollution around maternal dwelling place (3.63), maternal exposure to occupational hazards (3.53), maternal mental stress (2.48), paternal chronic disease (4.87), paternal exposure to occupational hazards (2.51), intake of vegetable/fruit (0.45), intake of fish/shrimp/meat/egg (0.59), and intake of milk/soymilk (0.55). After many trials, we selected a 3-layer BPNN model with 15, 12, and 1 neuron in the input, hidden, and output layers, respectively, as the best prediction model. The prediction model has accuracies of 0.91 and 0.86 on the training and testing sets, respectively. The sensitivity, specificity, and Yuden Index on the testing set (training set) are 0.78 (0.83), 0.90 (0
El Banayosy, Aly; Kizner, Lukacz; Arusoglu, Latif; Morshuis, Michael; Brehm, Christof; Koerfer, Reiner; Schuermann, Christoph; Smith, Richard G; Copeland, Jack G; Slepian, Marvin J
To enhance ambulation and facilitate hospital discharge of total artificial heart (TAH)-supported patients, we adapted a mobile ventricular assistance device (VAD) driver (Excor) for TAH use and report on the performance of Excor-driven TAH patients discharged home. Ten patients stabilized on a TAH, driven by the CSS ("Circulatory Support System"), were progressively switched over to the Excor in hospital over 14 days as a pilot, with daily hemodynamics and laboratory parameters measured. Twenty-two stable TAH patients were subsequently placed on the Excor, trained, and discharged home. Clinical and hemodynamic parameters were followed. All pilot study patients were clinically stable on the Excor, with no decrease in TAH output noted (6.3 + 0.3 L/min [day 1] vs. 5.8 + 0.2 L/min [day 14], p = 0.174), with a trend suggesting improvement of both hepatic and renal function. Twenty-two TAH patients were subsequently successfully discharged home on the portable driver and were supported out of hospital for up to 598 days (range, 2-598; mean = 179 ± 140 days), remaining ambulatory, New York Heart Association (NYHA) class I or II, and free of readmission for 88.5% of the time of support. TAH patients may be effectively and safely supported by a mobile drive system. As such, the utility of the TAH may be extended to support patients beyond the hospital, at home, with overall ambulatory freedom.
To enhance ambulation and facilitate hospital discharge of total artificial heart (TAH)–supported patients, we adapted a mobile ventricular assistance device (VAD) driver (Excor) for TAH use and report on the performance of Excor-driven TAH patients discharged home. Ten patients stabilized on a TAH, driven by the CSS (“Circulatory Support System”), were progressively switched over to the Excor in hospital over 14 days as a pilot, with daily hemodynamics and laboratory parameters measured. Twenty-two stable TAH patients were subsequently placed on the Excor, trained, and discharged home. Clinical and hemodynamic parameters were followed. All pilot study patients were clinically stable on the Excor, with no decrease in TAH output noted (6.3 + 0.3 L/min [day 1] vs. 5.8 + 0.2 L/min [day 14], p = 0.174), with a trend suggesting improvement of both hepatic and renal function. Twenty-two TAH patients were subsequently successfully discharged home on the portable driver and were supported out of hospital for up to 598 days (range, 2–598; mean = 179 ± 140 days), remaining ambulatory, New York Heart Association (NYHA) class I or II, and free of readmission for 88.5% of the time of support. TAH patients may be effectively and safely supported by a mobile drive system. As such, the utility of the TAH may be extended to support patients beyond the hospital, at home, with overall ambulatory freedom. PMID:24577369
Fraser, Charles D; Jaquiss, Robert D B
Options for long-term mechanical circulatory support to sustain pediatric heart failure patients requiring cardiac transplantation while they wait for donor hearts have been unsatisfactory. The conventional approach has been to use extracorporeal membrane oxygenation (ECMO), but its lack of feasibility for long-term use and the major complications associated with the technology have limited its use, especially in light of lengthy waiting lists for donor hearts. With the advent of the Berlin Heart EXCOR® Pediatric ventricular assist device (VAD), pediatric heart failure specialists have gained an important tool for helping this patient population survive until a donor heart can be identified. The EXCOR Pediatric VAD is designed to support pediatric patients of all age groups, from newborns to teenagers, and can be used successfully for many months. This paper describes the early experience with the EXCOR Pediatric VAD and the challenging journey undertaken to gain U.S. FDA approval, including successful completion of the first worldwide prospective clinical study of VADs in a pediatric population.
Yamagishi, Akio; Toyama, Yuki; Tobise, Fuminori; Ichimiya, Takahiro; Iwasaki, Hiroshi
Most of the thermometers used during operations are invasive and non-hygienic. The usefulness of a noncontact continuous tympanic thermometer under general anesthesia has been reported. We evaluated the usefulness of a noncontact continuous tympanic thermometer in patients undergoing cardiac surgery using an artificial heart-lung machine. Twenty patients scheduled to undergo cardiac surgery using an artificial heart-lung machine were selected for this study. After induction of general anesthesia, thermistor probes were inserted into the rectum and esophagus for measurements of rectal and esophageal temperatures, respectively. A noncontact continuous tympanic thermometer was inserted into the ear canal on the right side. These temperatures were monitored and recorded at one-minute intervals. Regression analysis and Bland-Altman analysis were used to compare the data (tympanic/rectal temperatures) with esophageal temperature as a core temperature. Tympanic temperature showed a good correlation with esophageal temperature (r=0.983, P<0.05). Rectal temperature also showed a good correlation with esophageal temperature (r=0.923, P<0.05), but the coefficient of correlation was low compared to that of tympanic temperature. The mean difference between tympanic temperature and esophageal temperature was -0.022 degrees C, and standard deviation (SD) was 0.395 degrees C. The mean difference between rectal temperature and esophageal temperature was -0.299 degrees C, and standard deviation (SD) was 0.838 degrees C. A noncontact continuous tympanic thermometer is useful for measurement of core temperature during cardiac surgery using an artificial heart-lung machine.
Granegger, Marcus; Aigner, Philipp; Haberl, Thomas; Mahr, Stephane; Tamez, Daniel A; Graham, Joel; Nunez, Nathalie J; Schima, Heinrich; Moscato, Francesco
New left ventricular assist devices (LVADs) offer both important advantages and potential hazards. VAD development requires better and expeditious ways to identify these advantages and hazards. We validated in an isolated working heart the hemodynamic performance of an intraventricular LVAD and investigated how its outflow cannula interacted with the aortic valve. Hearts from six pigs were explanted and connected to an isolated working heart setup. A miniaturized LVAD was implanted within the left ventricle (tMVAD, HeartWare Inc., Miami Lakes, FL, USA). In four experiments blood was used to investigate hemodynamics under various loading conditions. In two experiments crystalloid perfusate was used, allowing visualization of the outflow cannula within the aortic valve. In all hearts the transapical miniaturized ventricular assist device (tMVAD) implantation was successful. In the blood experiments hemodynamics similar to those observed clinically were achieved. Pump speeds ranged from 9 to 22 krpm with a maximum of 7.6 L/min against a pressure difference between ventricle and aorta of ∼50 mm Hg. With crystalloid perfusate, central positioning of the outflow cannula in the aortic root was observed during full and partial support. With decreasing aortic pressures the cannula tended to drift toward the aortic root wall. The tMVAD could unload the ventricle similarly to LVADs under conventional cannulation. Aortic pressure influenced central positioning of the outflow cannula in the aortic root. The isolated heart is a simple, accessible evaluation platform unaffected by complex reactions within a whole, living animal. This platform allowed detection and visualization of potential hazards. Copyright © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Jarvik, R K
Until recently, most artificial hearts have served as research tools to acquire further knowledge necessary ultimately to design practical systems for human use. Transcutaneous systems or percutaneous systems utilizing permanently implanted energy converters, batteries, and electronics packages have a number of substantial problems that would not exist if most system elements were kept outside the body. These problems include physiologic control, fit and fixation, foreign body infection, hermetic sealing, cable insulation and fatigue, inherent system complexity, stringent requirements for maintenance-free operation with long-term high reliability, and high cost. Percutaneous systems, particularly those in which only the blood pump is implanted, are an attractive choice for practical systems in the near future. A wearable, battery-powered electropneumatic total heart system should be developed.
Tarzia, Vincenzo; Braccioni, Fausto; Bortolussi, Giacomo; Buratto, Edward; Gallo, Michele; Bottio, Tomaso; Vianello, Andrea; Gerosa, Gino
Management of patients treated with CardioWest Total Artificial Heart (CW-TAH) as a bridge to heart transplantation (HTx) is complicated by difficulties in determining the optimal timing of transplantation. We present a case of a 53-year-old man supported as an outpatient with a CW-TAH, whose condition deteriorated following exchange of the portable driver. The patient was followed-up with serial cardiopulmonary exercise testing (CPET) which demonstrated a fall of peak VO2 to below 12 ml/kg/min following driver substitution, and the patient was subsequently treated with urgent orthotopic HTx. This case highlights the potential utility of CPET as a means for monitoring and indicating timing of HTx in patients with CW-TAH, as well as the potential for clinical deterioration following portable driver substitution.
Chatel, D; Martin-Bouyer, Y; Vicaut, E; Bouchoucha, H; Achard, F; Sablayrolles, J L; Carpentier, A
A quantitative study of cardiovascular anatomy was performed by obtaining three-dimensional reconstructions from regular computed tomography scan images in 15 patients, all candidates for heart transplantation. Volumetric estimates of the cardiovascular structures were obtained from these three-dimensional reconstructions using data directly related to total artificial heart (TAH) implantations. By using computerized three-dimensional modeling of these structures, reproducible measurements of the parameters defining the shape and the anatomical connections of the intrathoracic space available for TAH implantation could be derived. The results are intended to be used for both technical and clinical applications such as computer-assisted drawing of the pericardial cavity and the anatomical connections (useful for improving the design of TAH) and combined statistical calculations (multiple regressions, cluster algorithm) of the measurement results, which will then enable the best selection to be made among two or three TAH models for each patient.
Chair, Sek Ying; Yu, Doris SF; Ng, Michael Timothy; Wang, Qun; Cheng, Ho Yu; Wong, Eliza ML; Sit, Janet WH
Heart failure (HF) is a potentially fatal disease that affects increasing number of people worldwide. Although heart transplant is the “gold standard” therapy for HF, due to the limited availability of organs, many patients died when waiting for the transplant. Left ventricular assist device (LVAD), as a mechanical circulatory support, has become a new light for patients with HF. With the technical advancements, LVADs work not only as a bridge to transplant, but also assist heart recovery and even as a destination therapy in long-term treatment. This observation paper reviewed the development of LVAD and its clinical roles. The challenges and possible solutions in nursing care for patients with LVAD at different stage of implantation were discussed. The healthcare professionals could obtain a better understanding about the LVAD treatment for HF patients. PMID:27594870
Chair, Sek Ying; Yu, Doris Sf; Ng, Michael Timothy; Wang, Qun; Cheng, Ho Yu; Wong, Eliza Ml; Sit, Janet Wh
Heart failure (HF) is a potentially fatal disease that affects increasing number of people worldwide. Although heart transplant is the "gold standard" therapy for HF, due to the limited availability of organs, many patients died when waiting for the transplant. Left ventricular assist device (LVAD), as a mechanical circulatory support, has become a new light for patients with HF. With the technical advancements, LVADs work not only as a bridge to transplant, but also assist heart recovery and even as a destination therapy in long-term treatment. This observation paper reviewed the development of LVAD and its clinical roles. The challenges and possible solutions in nursing care for patients with LVAD at different stage of implantation were discussed. The healthcare professionals could obtain a better understanding about the LVAD treatment for HF patients.
Bazylev, V V; Nemchenko, E V; Karnakhin, V A; Pavlov, A A; Mikulyak, A I
Advantages and shortcomings of aortocoronary bypass grafting on the beating heart and in the conditions of artificial circulation (AC) have long been discussed. The data on patency of bypass grafts in the remote period are indicative of comparable results of operations with and without AC or advantages of using AC. In order to determine benefits of each method it is necessary to reveal intraoperative predictors of bypass grafts occlusion in the remote period. We analyzed the results of ultrasound flowmetry of the blood flow through the left internal thoracic artery during bypass grafting of the anterior descending artery with the use of AC and on the beating heart. A retrospective study included a total of 352 patients subdivided into 2 groups: Group One was composed of 120 patients undergoing surgery in the conditions of AC and Group Two comprised 232 patients subjected to similar operations on the beating heart. Blood flow was measured with the help of flowmeter VeryQ MediStim® after termination of AC and inactivation of heparin by protamine, with systolic pressure of 100-110 mm Hg. There were no statistically significant differences between the groups by the diameter and degree of stenosis of the anterior descending artery, diameter of the left internal thoracic artery. The mean volumetric blood flow velocity (Qmean) along the shunts in Group One was higher (p=0.01). No statistically significant differences by the pulsatility index (PI) between the groups were revealed (p=0.2). A conclusion was drawn that coronary bypass grafting of the anterior descending artery by the left internal thoracic artery in the conditions of artificial circulation made it possible to achieve higher volumetric velocity of blood flow through the conduit as compared with operations on the beating heart, with similar resistance index. The immediate results of the operations with the use of the both techniques did not differ.
Japan's Ministry of Health will fund a major new heart transplantation project in an effort to resume heart transplants halted by a public outcry against the first such transplant 17 years ago. Opposition to organ donation, which has been attributed variously to Buddhist and Confucian views of the body and to Japanese cultural values, has resulted in the heaviest use of renal dialysis per capita in the world and to an interest in artificial heart research. Goals of the heart transplant project are first to win public support and then to promote research on animal transplants, organ preservation, a distribution system, immunological control mechanisms, and artificial hearts as backup devices.
Shaikh, Asad F; Joseph, Susan M; Lima, Brian; Hall, Shelley A; Malyala, Rajasekhar; Rafael, Aldo E; Gonzalez-Stawinski, Gonzalo V; Chamogeorgakis, Themistokles
Background Left ventricular assist devices (LVADs) have revolutionized the treatment of patients with end-stage heart failure. These devices are replaced when pump complications arise if heart transplant is not possible. We present our experience with HeartMate II (HMII (Thoratec, Plesanton, California, United States)) LVAD pump exchange. Materials and Methods We retrospectively reviewed all cases that required pump exchange due to LVAD complication from November 2011 until June 2016 at a single high-volume institution. The indications, demographics, and outcome were extracted and analyzed. Results Of 250 total patients with implanted HMII LVADs, 16 (6%) required pump exchange during the study period. The initial indications for LVAD placement in these patients were bridge to transplantation (n = 6 [37.5%]) or destination therapy (n = 10 [62.5%]). Fifteen patients (93.8%) required pump exchange due to pump thrombosis and 1 (6.2%) due to refractory driveline infection. Nine patients (56.2%) underwent repeat median sternotomy while a left subcostal approach was used in the remaining seven patients. Fifteen patients (93.7%) survived until hospital discharge. During the follow-up period (median, 155 days), 11 patients remained alive and 4 of these underwent successful cardiac transplantation. Conclusion HMII LVAD pump exchange can be safely performed for driveline infection or pump thrombosis when heart transplantation is not an option.
MacGowan, Guy A; Wrightson, Neil; Robinson-Smith, Nicola; Woods, Andrew; Parry, Gareth; Gould, Kate; Schueler, Stephan
To manage myocardial recovery in patients with the HeartWare left ventricular assist device (HVAD), we describe a minimally invasive approach (decommissioning) that involves disconnecting the driveline and occluding the outflow tract through a small left thoracotomy incision, leaving the device in situ, in conjunction with optimal medical therapies and comprehensive assessment of left ventricular recovery. Nine patients (all male, 37 ± 12 years, all nonischemic dilated cardiomyopathy) had an HVAD implanted for 766 ± 343 days. When left ventricular function improved to mild impairment by echocardiography, patients underwent assessment at reduced flow (2578 ± 148 to 1822 ± 67 rpm) with documentation of compensated right heart hemodynamics and ejection fraction 52 ± 8%. Eight of nine patients underwent decommissioning, and 1 patient had a hybrid procedure of percutaneous occlusion of outflow graft and surgical division of driveline. Two patients died postoperatively at 413 days (sepsis) and 810 days (heart failure). In conclusion, in selected patients with nonischemic dilated cardiomyopathy, a prolonged period of HVAD support in conjunction with heart failure medications can lead to recovery of left ventricular function. Surgical decommissioning is then an option to remove these patients from support. These patients are, however, not cured and remain at risk for future deterioration in ventricular function and infections.
Frazier, O H; Cohn, William E
We implanted a continuous-flow total heart replacement device in a 55-year-old man who had severe end-stage heart failure due to amyloidosis and no other options for treatment. The device was composed of 2 modified HeartMate II ventricular assist pumps. After the implantation, our patient recovered normal neurologic function and was able to converse with his family and work on his computer. He died of multisystem organ failure caused by severe amyloidosis 5 weeks after the implantation. During the past 6 years, we have been developing and testing various technological iterations for total heart replacement in our animal laboratory and have achieved survival periods as long as 90 days in calves. We describe the development, preclinical trials, and adaptation for human use of the modified HeartMate II apparatus, as well as its role in our patient's survival.
Tapia, Jesus A; Herrera-May, Agustin L; García-Ramírez, Pedro J; Martinez-Castillo, Jaime; Figueras, Eduard; Flores, Amira; Manjarrez, Elías
We describe a simple procedure to characterize a magnetic field sensor based on microelectromechanical systems (MEMS) technology, which exploits the Lorentz force principle. This sensor is designed to detect, in future applications, the spiking activity of neurons or muscle cells. This procedure is based on the well-known capability that a magnetic MEMS device can be used to sense a small magnetic flux density. In this work, an electronic neuron (FitzHugh-Nagumo) is used to generate controlled spike-like magnetic fields. We show that the magnetic flux density generated by the hardware of this neuron can be detected with a new MEMS magnetic field sensor. This microdevice has a compact resonant structure (700 × 600 × 5 μm) integrated by an array of silicon beams and p-type piezoresistive sensing elements, which need an easy fabrication process. The proposed microsensor has a resolution of 80 nT, a sensitivity of 1.2 V.T(-1), a resonant frequency of 13.87 kHz, low power consumption (2.05 mW), quality factor of 93 at atmospheric pressure, and requires a simple signal processing circuit. The importance of our study is twofold. First, because the artificial neuron can generate well-controlled magnetic flux density, we suggest it could be used to analyze the resolution and performance of different magnetic field sensors intended for neurobiological applications. Second, the introduced MEMS magnetic field sensor may be used as a prototype to develop new high-resolution biomedical microdevices to sense magnetic fields from cardiac tissue, nerves, spinal cord, or the brain.
Brock, David L.
Among the many ideas and theories in anatomy and physiology, one particular topic provides all the potential benefits of learning about the human body: the circulatory system, specifically the heart. Describes a distinctive way to study circulation and the heart that allows students to explore the basic principles of vertebrate anatomy and…
Brock, David L.
Among the many ideas and theories in anatomy and physiology, one particular topic provides all the potential benefits of learning about the human body: the circulatory system, specifically the heart. Describes a distinctive way to study circulation and the heart that allows students to explore the basic principles of vertebrate anatomy and…
Ladich, Elena; Otsuka, Fumiyuki; Virmani, Renu
We sought to evaluate the pathologic findings of the percutaneous Parachute device implanted in patients with severe heart failure (HF). Currently, most treatments of HF rest on optimal medical therapy with adjunctive interventional or surgical palliative treatments. One such treatment is the Parachute device, which partitions the left ventricle excluding the scarred myocardium from functioning myocardium, and has shown promise in clinical studies. We have examined histopathologically seven cases [six males (age range 43–74 years; mean 56 years) and one female (55 years)] of Parachute device that were either retrieved at autopsy (n = 4) or during transplantation (n = 3); implant duration, 15-1,533 days. Three patients died of cardiac causes and none died from complications. Histologic early changes (<30 days, n = 1) included adherent thrombus, with focal neutrophil infiltration and degenerating inflammatory cells. Over time (31–300 days, n = 4), there was organized thrombus and development of neoendocardial thickening especially at the free-edge of the device and its contact with the adjacent endocardium while the base of the device showed varying degrees of fibrin thrombus. The greatest organization of thrombus was observed in devices removed at >300 days (680 and 1533 days); both had fractures of the foot along with strut fracture and one had tearing of the expanded polytetrafluoroethylene. The percutaneous Parachute device appears as a promising adjunctive treatment for patients suffering from severe HF. The pathologic changes are those of organizing thrombus with and without inflammation with minor complications of foot and strut fracture.
Khazanie, Prateeti; Hammill, Bradley G; Patel, Chetan B; Kiernan, Michael S; Cooper, Lauren B; Arnold, Suzanne V; Fendler, Timothy J; Spertus, John A; Curtis, Lesley H; Hernandez, Adrian F
Use of left ventricular assist devices (LVADs) for treatment of advanced heart failure has expanded significantly over the past decade. However, concomitant use of heart failure medical therapies after implant is poorly characterized. We examined the use of heart failure medications before and after LVAD implant in adult patients enrolled in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) between 2008 and 2013 (N = 9359). Using logistic regression, we examined relationships between patient characteristics and medication use at 3 months after implant. Baseline rates of heart failure therapies before implant were 38% for angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), 55% for β-blockers, 40% for mineralocorticoid receptor antagonists (MRAs), 87% for loop diuretics, 54% for amiodarone, 11% for phosphodiesterase inhibitors, 22% for warfarin, and 54% for antiplatelet agents. By 3 months after implant, the rates were 50% for ACE inhibitors or ARBs, 68% for β-blockers, 33% for MRAs, 68% for loop diuretics, 42% for amiodarone, 21% for phosphodiesterase inhibitors, 92% for warfarin, and 84% for antiplatelet agents. In general, age, preimplant INTERMACS profile, and prior medication use were associated with medication use at 3 months. Overall use of neurohormonal antagonists was low after LVAD implant, whereas use of loop diuretics and amiodarone remained high. Heart failure medication use is highly variable, but appears to generally increase after LVAD implantation. Low neurohormonal antagonist use may reflect practice uncertainty in the clinical utility of these medications post-LVAD. Copyright © 2016. Published by Elsevier Inc.
Khazanie, Prateeti; Hammill, Bradley G.; Patel, Chetan B.; Kiernan, Michael S.; Cooper, Lauren B.; Arnold, Suzanne V.; Fendler, Timothy J.; Spertus, John A.; Curtis, Lesley H.; Hernandez, Adrian F.
Background Use of left ventricular assist devices (LVADs) for treatment of advanced heart failure has expanded significantly over the past decade. However, concomitant use of heart failure medical therapies after implant is poorly characterized. Methods and Results We examined the use of heart failure medications before and after LVAD implant in adult patients enrolled in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) between 2008 and 2013 (N = 9359). Using logistic regression, we examined relationships between patient characteristics and medication use at 3 months after implant. Baseline rates of heart failure therapies before implant were 38% for angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), 55% for β-blockers, 40% for mineralocorticoid receptor antagonists (MRAs), 87% for loop diuretics, 54% for amiodarone, 11% for phosphodiesterase inhibitors, 22% for warfarin, and 54% for antiplatelet agents. By 3 months after implant, the rates were 50% for ACE inhibitors or ARBs, 68% for β-blockers, 33% for MRAs, 68% for loop diuretics, 42% for amiodarone, 21% for phosphodiesterase inhibitors, 92% for warfarin, and 84% for antiplatelet agents. In general, age, pre-implant INTERMACS profile, and prior medication use were associated with medication use at 3 months. Conclusions Overall use of neurohormonal antagonists was low after LVAD implant, whereas use of loop diuretics and amiodarone remained high. Heart failure medication use is highly variable but appears to generally increase after LVAD implantation. Low neurohormonal antagonist use may reflect practice uncertainty in the clinical utility of these medications post-LVAD. PMID:26892975
Gemmato, Courtney J.; Forrester, Matthew D.; Myers, Timothy J.; Frazier, O. H.; Cooley, Denton A.
Since the 1960s, the Texas Heart Institute has been intimately involved in the development of mechanical circulatory support devices (for example, ventricular assist devices, aortic counterpulsation pumps, and total artificial hearts) for both short- and long-term use. Here, we review the varied clinical experience with these technologies at the Texas Heart Institute over the last 35 years. PMID:16107108
Shiose, Akira; Nowak, Kathleen; Horvath, David J.; Massiello, Alex L.; Golding, Leonard A.R.; Fukamachi, Kiyotaka
This study demonstrated the concept of using speed modulation in a continuous-flow total artificial heart (CFTAH) to shape arterial pressure waveforms and to adjust pressure pulsatility. A programmable function generator was used to determine the optimum pulsatile speed profile. Three speed profiles (sinusoidal, rectangular, and optimized [a profile optimized for generation of a physiologic arterial pressure waveform]) were evaluated using the CFTAH mock circulatory loop. Hemodynamic parameters were recorded at average pump speeds of 2,700 rpm and a modulation cycle of 60 beats per minute. The effects of varying physiologically relevant vascular resistance and lumped compliance on the hemodynamics were assessed. The feasibility of using speed modulation to manipulate systemic arterial pressure waveforms, including a physiologic pressure waveform, was demonstrated in vitro. The additional pump power consumption needed to generate a physiologic pulsatile pressure was 16.2% of the power consumption in nonpulsatile continuous-flow mode. The induced pressure waveforms and pulse pressure were shown to be very responsive to changes in both systemic vascular resistance and arterial compliance. This system also allowed pulsatile pulmonary arterial waveform. Speed modulation in the continuous-flow total artificial heart could enable physicians to obtain desired pressure waveforms by simple manual adjustment of speed control input waveforms. PMID:20616704
Shiraishi, Y; Yambe, T; Yoshizawa, M; Hashimoto, H; Yamada, A; Miura, H; Hashem, M; Kitano, T; Shiga, T; Homma, D
Annuloplasty for functional mitral or tricuspid regurgitation has been made for surgical restoration of valvular diseases. However, these major techniques may sometimes be ineffective because of chamber dilation and valve tethering. We have been developing a sophisticated intelligent artificial papillary muscle (PM) by using an anisotropic shape memory alloy fiber for an alternative surgical reconstruction of the continuity of the mitral structural apparatus and the left ventricular myocardium. This study exhibited the mitral regurgitation with regard to the reduction in the PM tension quantitatively with an originally developed ventricular simulator using isolated goat hearts for the sophisticated artificial PM. Aortic and mitral valves with left ventricular free wall portions of isolated goat hearts (n=9) were secured on the elastic plastic membrane and statically pressurized, which led to valvular leaflet-papillary muscle positional change and central mitral regurgitation. PMs were connected to the load cell, and the relationship between the tension of regurgitation and PM tension were measured. Then we connected the left ventricular specimen model to our hydraulic ventricular simulator and achieved hemodynamic simulation with the controlled tension of PMs.
Gambi, Ennio; Agostinelli, Angela; Belli, Alberto; Burattini, Laura; Cippitelli, Enea; Fioretti, Sandro; Pierleoni, Paola; Ricciuti, Manola; Sbrollini, Agnese; Spinsante, Susanna
Contactless detection is one of the new frontiers of technological innovation in the field of healthcare, enabling unobtrusive measurements of biomedical parameters. Compared to conventional methods for Heart Rate (HR) detection that employ expensive and/or uncomfortable devices, such as the Electrocardiograph (ECG) or pulse oximeter, contactless HR detection offers fast and continuous monitoring of heart activities and provides support for clinical analysis without the need for the user to wear a device. This paper presents a validation study for a contactless HR estimation method exploiting RGB (Red, Green, Blue) data from a Microsoft Kinect v2 device. This method, based on Eulerian Video Magnification (EVM), Photoplethysmography (PPG) and Videoplethysmography (VPG), can achieve performance comparable to classical approaches exploiting wearable systems, under specific test conditions. The output given by a Holter, which represents the gold-standard device used in the test for ECG extraction, is considered as the ground-truth, while a comparison with a commercial smartwatch is also included. The validation process is conducted with two modalities that differ for the availability of a priori knowledge about the subjects' normal HR. The two test modalities provide different results. In particular, the HR estimation differs from the ground-truth by 2% when the knowledge about the subject's lifestyle and his/her HR is considered and by 3.4% if no information about the person is taken into account.
Shumakov, V I; Tolpekin, V E; Melemuka, I V; Kiselev, Y M; Chaustov, A I
Intraventricular blood-forcing-principle-based pneumo- and hydraulic assistance circulation device test results are proposed. The system consists of a uninipple valveless dome pump, a pneumo- or hydraulic drive, and an artificial pericardium. Stand tests of these systems and medical-biologic experiments on dogs and 17 calves were performed. The duration of these experiments was up to several days. In this report, the features of surgical techniques, perfusion parameters, control principles, hemodynamic variations, complications, and other problems concerning realization of the proposed method are discussed.
Crews, Kelly A; Kaiser, Samantha L; Walczak, Richard J; Jaquiss, Robert D B; Lodge, Andrew J
A 10-year-old boy was admitted with dilated cardiomyopathy. Before scheduled implantation of a HeartWare ventricular assist device, he experienced a cardiac arrest and required extracorporeal membrane oxygenation for both cardiac and pulmonary support. After 4 days of extracorporeal membrane oxygenation and 126 days of support on the HeartWare ventricular assist device, he underwent successful cardiac transplantation. He is doing well 6 months after transplantation.
Moshkivska, L V; Nastenko, E A; Golovenko, O S; Lazoryshynets, V V
The risk factors of pulmonary complications occurrence were analyzed in children, operated on for inborn heart failures in atrificial blood circulation environment. Pulmonary complications rate and the risk factors of their occurrence were analyzed.
Liu, Xiaomin; Chen, Hung-Cheng; Kong, Xianggui; Zhang, Youlin; Tu, Langping; Chang, Yulei; Wu, Fei; Wang, Tongtong; Reek, Joost N H; Brouwer, Albert M; Zhang, Hong
We provide the first demonstration of a near infrared light driven water oxidation reaction in a molecule-based artificial photosynthetic device using an upconversion nano-photosensitizer. One very attractive advantage of this system is that using NIR light irradiation does not cause significant photodamage, a serious problem in molecular based artificial photosynthesis under visible light irradiation.
Kapitola, J; Kölbel, F; Schüllerová, M; Schreiberová, O; Vilimovská, D
The effect of various autonomic blockers on the heart rate (from the ECG recording) of intact rats and of animals with experimental hyperthyroidism induced by the administration of dried thyroid was studied. In intact rats, the heart rate fell significantly (by 22%) during the first week after the peroral administration of propranolol (0.05% in food), but trimepranol (0.02%), reserpine (0.001%) and guanethidine (0.1%) had no effect (in a suplementary experment, a small, but statistically significant decrease was also found after trimepranol). In experimental hyperthyroidism, using the same blocker doses, the heart rate fell significantly after propranolol (by 23%), trimepranol (22%), reserpine (16%) and, in a preliminary experiment, guanethidine (19%). On injecting 0.05 mg propranolol intravenously, the maximum drop in the heart rate in intact rats was 22%, while in hyperthyroidism it was hardly more than half this value (at all the intervals from 2 to 30 minutes the decrease was statistically significant). Practolol, in a dose of 0.3 mg i.v., was less effective -- in intact rats the heart rate fell by not more than 12% (at all the intervals from 2 to 30 minutes the decrease was significant), but in hyperthyroidism the drop was slower and statistically non-significant. The results do not furnish an unequivocal answer to the question of the role of adrenergic regulation of the heart rate under physiological conditions and in experimental hyperthyroidism in rats.
Jacobs, Peter G.; Resalat, Navid; El Youssef, Joseph; Reddy, Ravi; Branigan, Deborah; Preiser, Nicholas; Condon, John; Castle, Jessica
In this article, we present several important contributions necessary for enabling an artificial endocrine pancreas (AP) system to better respond to exercise events. First, we show how exercise can be automatically detected using body-worn accelerometer and heart rate sensors. During a 22 hour overnight inpatient study, 13 subjects with type 1 diabetes wearing a Zephyr accelerometer and heart rate monitor underwent 45 minutes of mild aerobic treadmill exercise while controlling their glucose levels using sensor-augmented pump therapy. We used the accelerometer and heart rate as inputs into a validated regression model. Using this model, we were able to detect the exercise event with a sensitivity of 97.2% and a specificity of 99.5%. Second, from this same study, we show how patients’ glucose declined during the exercise event and we present results from in silico modeling that demonstrate how including an exercise model in the glucoregulatory model improves the estimation of the drop in glucose during exercise. Last, we present an exercise dosing adjustment algorithm and describe parameter tuning and performance using an in silico glucoregulatory model during an exercise event. PMID:26438720
Jacobs, Peter G; Resalat, Navid; El Youssef, Joseph; Reddy, Ravi; Branigan, Deborah; Preiser, Nicholas; Condon, John; Castle, Jessica
In this article, we present several important contributions necessary for enabling an artificial endocrine pancreas (AP) system to better respond to exercise events. First, we show how exercise can be automatically detected using body-worn accelerometer and heart rate sensors. During a 22 hour overnight inpatient study, 13 subjects with type 1 diabetes wearing a Zephyr accelerometer and heart rate monitor underwent 45 minutes of mild aerobic treadmill exercise while controlling their glucose levels using sensor-augmented pump therapy. We used the accelerometer and heart rate as inputs into a validated regression model. Using this model, we were able to detect the exercise event with a sensitivity of 97.2% and a specificity of 99.5%. Second, from this same study, we show how patients' glucose declined during the exercise event and we present results from in silico modeling that demonstrate how including an exercise model in the glucoregulatory model improves the estimation of the drop in glucose during exercise. Last, we present an exercise dosing adjustment algorithm and describe parameter tuning and performance using an in silico glucoregulatory model during an exercise event. © 2015 Diabetes Technology Society.
Petrucci, Ralph J; Wright, Susan; Naka, Yoshifuma; Idrissi, Kathy A; Russell, Stuart D; Dordunoo, Dzifa; Jaski, Brian; Chillcott, Suzanne; Feldman, David; Yanssens, Tammy; Heatley, Gerald; Koundakjian, Lalig; Farrar, David J; Aaronson, Keith D
Neurocognitive (NC) changes in heart failure patients receiving left ventricular assist devices (LVADs) are not well understood. The purpose of this study was to document changes in the cognitive performance of patients with the continuous-flow HeartMate II LVAD as a bridge to transplant (BTT). A NC protocol was used to evaluate patient performance at 1, 3 and 6 months after LVAD implantation at 11 centers. A total of 239 test sessions were completed in 93 patients including paired evaluations in 51 to 57 patients from 1 to 3 months, and in 20 to 28 patients with results from 1, 3 and 6 months. Five NC domains were assessed, including visual spatial perception, auditory and visual memory, executive functions, language and processing speed. There were statistically significant (p < 0.05), but limited improvements between 1, 3 and 6 months in NC domain performances as seen in visual memory, executive functions, visual spatial perception and processing speed. There were no significant declines in any neurocognitive test in any domain over these time periods. The cognitive performance of advanced heart failure patients remained stable or showed slight improvements from Month 1 to Month 6 of continuous-blood-flow support with the HeartMate II LVAD.
Thomas, Bernadette A; Logar, Christine M; Anderson, Arthur E
"Cardiorenal syndrome" is a term used to describe a dys-regulation of the heart affecting the kidneys, or vice versa, in an acute or chronic manner (1,2). Renal impairment can range from reversible ischemic damage to renal failure requiring short- or long-term renal replacement therapy (2). Patients who require mechanical circulatory support, such as a left ventricular assist device (LVAD), as definitive treatment for congestive heart failure or as a bridge to cardiac transplantation pose a unique challenge with respect to receiving dialysis, because they experience higher rates of morbidity and mortality from infection in the post-LVAD period (3-7). Acute dialysis access can pose an increased infection risk. In this article, we present a patient who required renal replacement therapy and a LVAD for management of acute-on-chronic cardiorenal syndrome while awaiting heart transplantation. A literature review to determine whether peritoneal dialysis or hemodialysis is superior for patients with profound hemodynamic dysfunction and the need to minimize risk of infection did not offer clear guidance about which modality is superior in patients with advanced congestive heart failure. However, there is clear evidence of the superiority of peritoneal dialysis in reducing the risk of systemic infection secondary to acute dialysis access. Given the high risk of LVAD infection, we therefore conclude that, to decrease mortality secondary to systemic infection, peritoneal dialysis should strongly be considered in patients who require renal replacement therapy before or after LVAD placement.
Blair, Tara Leslie
Traditional methods of heart failure (HF) management are based on reactive strategies to treat late indicators of decompensated HF. Advances in monitoring methods have become available with the evolution of implantable cardioverter-defibrillators and cardiac-resynchronization therapy devices. These devices provide new diagnostic data and remote monitoring capabilities that allow clinicians to proactively monitor patients for earlier signs of worsening HF. The integration of data obtained from implantable cardioverter-defibrillator and cardiac-resynchronization therapy technology could improve outpatient HF care, potentially leading to decreased readmission rates and improved patient outcomes. This review will synthesize the literature regarding the efficacy of device diagnostic data and the usability of the data in the clinical setting. Articles for review were obtained using Cumulative Index to Nursing and Allied Health Literature, MEDLINE, PubMed, and ClinicalTrials.gov. Device diagnostics showed strong correlation with established HF biomarkers and hemodynamic measures. The findings from this review indicate that device diagnostic parameters predict impending HF much earlier than traditional methods of monitoring do. Device diagnostics are also more accurate in the early prediction of HF when compared with noninvasive objective measures, particularly when multiple parameters are combined and monitored for trends. Device diagnostics possess a distinct advantage over traditional methods of monitoring for HF because they allow clinicians to remotely monitor the status of their HF patients without relying on patient compliance for data entry and reporting. Studies regarding the efficacy of device diagnostic parameters suggest that their integration into clinical practice will provide a more accurate and reliable mechanism for assisting clinicians in risk stratifying and predicting potential episodes of decompensated HF.
Leopaldi, A M; Vismara, R; van Tuijl, S; Redaelli, A; van de Vosse, F N; Fiore, G B; Rutten, M C M
Integration of biological samples into in vitro mock loops is fundamental to simulate real device's operating conditions. We developed an in vitro platform capable of simulating the pumping function of the heart through the external pressurization of the ventricle. The system consists of a fluid-filled chamber, in which the ventricles are housed and sealed to exclude the atria from external loads. The chamber is connected to a pump that drives the motion of the ventricular walls. The aorta is connected to a systemic impedance simulator, and the left atrium to an adjustable preload. The platform reproduced physiologic hemodynamics, i.e. aortic pressures of 120/80 mmHg with 5 L/min of cardiac output, and allowed for intracardiac endoscopy. A pilot study with a left ventricular assist device (LVAD) was also performed. The LVAD was connected to the heart to investigate aortic valve functioning at different levels of support. Results were consistent with the literature, and high speed video recordings of the aortic valve allowed for the visualization of the transition between a fully opening valve and a permanently closed configuration. In conclusion, the system showed to be an effective tool for the hemodynamic assessment of devices, the simulation of surgical or transcatheter procedures and for visualization studies. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.
Dimitrov, Kamen; Riebandt, Julia; Haberl, Thomas; Wiedemann, Dominik; Simon, Paul; Laufer, Günther; Schima, Heinrich; Zimpfer, Daniel
We report the echocardiographic detection of microbubbles in the outflow prosthesis of a HeartWare HVAD left ventricular assist device using transthoracic echocardiography. In this case it was a specific sign associated with device thrombosis that resolved after successful treatment with systemic thrombolysis.
Uriel, Nir; Adatya, Sirtaz; Malý, Jiří; Kruse, Eric; Rodgers, Daniel; Heatley, Gerald; Herman, Aleš; Sood, Poornima; Berliner, Dominik; Bauersachs, Johann; Haverich, Axel; Želízko, Michael; Schmitto, Jan D; Netuka, Ivan
The HeartMate 3 (HM3) is a Conformiteé Européenne (CE) mark-approved left ventricular assist device (LVAD) with a fully magnetically levitated rotor with features consisting of a wide range of operational speeds, wide flow paths and an artificial pulse. We performed a hemodynamic and echocardiographic evaluation of patients implanted with the HM3 LVAD to assess the speed range for optimal hemodynamic support. Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP] and blood pressure [BP]) and 3-dimensional echocardiography (3DE). Data were recorded at up to 13 speed settings. Speed changes were in steps of 100 revolutions per minute (rpm), starting at 4,600 rpm and ramping up to 6,200 rpm. Mean original speed was 5,306 ± 148 rpm, with a majority of patients (10 of 16, 62.5%) having normal CVPs and PCWPs at their original rpm settings. Going from lowest to highest speeds, cardiac output improved at the rate of 0.08 ± 0.08 liter/min per 100 rpm (total change 1.25 ± 1.20 liters/min) and PCWP decreased at the rate of -0.48 ± 0.27 mm Hg per 100 rpm (total change -6.13 ± 3.72 mm Hg). CVP and systolic BP did not change significantly with changes in rpm. Left ventricular end-diastolic dimension (LVEDD) decreased at a rate of -0.15 ± 0.09 cm per 100 rpm. Number of rpm was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 13 (81.3%) patients. For the remaining 3 patients, medical management was pursued to optimize hemodynamic support. Hemodynamic normalization of pressures was achieved in the majority of patients implanted with the HM3 pump within a narrow speed range. Copyright © 2016 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.
Tuba Demirozu, Zumrut; Suha Kucukaksu, Deniz
Long-term mechanical circulatory support is a life-saving technology while briding to heart transplantation. It increases the quality of life and preserves end-organ function for patients with advanced heart failure. The number of patients with advanced heart failure scheduled for heart transplantation before comorbidities escalate is on the rise. However, the device function is complicated by the bleeding-thrombosis and infection paradigm, hence the interest in understanding device thrombosis and infection. We describe a 27-year-old man with idiopathic cardiomyopathy, advanced end-organ failure, and severe infection, who was bridged to heart transplantation after 8 months on the Berlin Heart EXCOR (Berlin Heart AG, Berlin, Germany) biventricular support. The patient was discharged from the hospital in the third postoperative week after the recovery of his end-organ functions. At 29 months’ post-transplantation follow-up, his last cardiac biopsy was grade 0, his ejection fraction was 60%, and he was enjoying a good quality of life. PMID:26985209
The new classification of heart failure in the American College of Cardiology/American Heart Association guidelines includes stage D, which is refractory severe heart failure that does not respond to medical or resynchronization therapy. Among the many treatment strategies for stage D heart failure, only heart transplantation and ventricular assist devices have been established as improving prognosis. With the evolution in the mechanics of ventricular assist devices in recent years, the postoperative prognosis has improved, and less sick patients can now be candidates for these devices. In Japan, 2 continuous flow devices have been approved since April 2011, and now is the best time to consider the indications for their use.
Kamohara, Keiji; Weber, Stephan; Klatte, Ryan S; Luangphakdy, Viviane; Flick, Christine R; Ootaki, Yoshio; Akiyama, Masatoshi; Cingoz, Faruk; Ootaki, Chiyo; Kopcak, Michael W; Liu, Jenny; Chen, Ji-Feng; Navia, Jose L; Smith, William A; Fukamachi, Kiyotaka
To evaluate the effects of downsizing of the total artificial heart (TAH), we compared the anaerobic threshold (AT) values in calves with two different types of TAH (Cleveland Clinic-Nimbus TAH and the downsized MagScrew TAH). Exercise studies were performed using a treadmill in 12 calves. During the exercise, parameters to obtain the AT were measured. To evaluate the determinants of the AT, a linear regression analysis was performed between AT and potential variables. AT values from 29 studies revealed no significant differences between the two different TAHs, with no significant differences in hemodynamic or oxygen metabolic parameters. AT values correlated well with pump flow/body weight (Q) multiplied by the hemoglobin level, regardless of the TAH used. In conclusion, downsizing of the original TAH design did not reduce AT without any significant differences in hemodynamic or oxygen metabolic parameters during exercise in calves.
Krokstrom, Ann-Katrin; Higgins, Thomas; Johansson, Sune; Jögi, Peeter
We report the implantation of the Berlin Heart EXCOR (Berlin Heart, Berlin, Germany) as a pediatric biventricular assist device in a 10-month-old boy with primary graft failure after cardiac transplantation. The EXCOR was successfully used as a bridge to cardiac retransplantation. The pneumatically driven paracorporeal device supported the patient for 165 days until another suitable heart was obtained.
Shoham, Allen B; Patel, Bhavesh; Arabia, Francisco A; Murray, Michael J
Many patients with end-stage cardiomyopathy are now being implanted with Total Artificial Hearts (TAHs). We have observed individual cases of post-operative mechanical ventilator autocycling with a flow trigger, and subsequent loss of autocycling after switching to a pressure trigger. These observations prompted us to do a retrospective review of all TAH devices placed at our institution between August 2007 and May 2009. We found that in the immediate post-operative period following TAH placement, autocycling was present in 50% (5/10) of cases. There was immediate cessation of autocycling in all patients after being changed from a flow trigger of 2 L/minute to a pressure trigger of 2 cm H2O. The autocycling group was found to have significantly higher CVP values than the non-autocycling group (P = 0.012). Our data suggest that mechanical ventilator autocycling may be resolved or prevented by the use of a pressure trigger rather than a flow trigger setting in patients with TAHs who require mechanical ventilation.
Sauer, I M; Frank, J; Spiegelberg, A; Bücherl, E S
A new electromechanical energy converting system has been developed to yield an efficient and durable orthotopic total artificial heart (TAH). The energy converter we developed transforms the unidirectional rotational motion of the motor into a longitudinal forward-reverse movement of an internal geared oval, linked directly to pusher plates on both sides. To ensure a permanent positive connection between the drive gear and the internally geared wheel, a ball bearing runs inside an oval shaped guide track. Motor, gear unit, and conical pusher plates are seated between alternately ejecting and filling ventricles. The unidirectional motion of the brushless DC motor affords easier motor control, reduces energy demand, and ensures longer life of the motor when compared with a bidirectional motion system. In vitro testing has been performed on a mock circulation loop. The overall system efficiency of the TAH Ovalis was 27-39% (mean, 36%) for the pump output range of 2-7 L/min. The maximum output of 7 L/min can be obtained with a pump rate of 130 min(-1) and an afterload pressure of 140 mm Hg. For an average sized human with a mean cardiac output of 6 L/min at a mean aortic pressure of 120 mm Hg, 5 watts of input power would be required. The size of the prototype is 560 cm3, the weight is 950 g. Our first in vitro studies demonstrated the excellent efficiency and pump performance of this new electromechanical energy converter. The results prove the feasibility of this new concept's use as an energy converter for a total artificial heart.
Elorriaga, Natalia; Garay, Osvaldo U; Poggio, Rosana; Caporale, Joaquin; Matta, Maria G; Augustovski, Federico; Pichon-Riviere, Andres; Mozaffarian, Dariush
Abstract Objective To estimate the impact of Argentine policies to reduce trans fatty acids (TFA) on coronary heart disease (CHD), disability-adjusted life years (DALYs) and associated health-care costs. Methods We estimated the baseline intake of TFA before 2004 to be 1.5% of total energy intake. We built a policy model including baseline intake of TFA, the oils and fats used to replace artificial TFAs, the clinical effect of reducing artificial TFAs and the costs and DALYs saved due to averted CHD events. To calculate the percentage of reduction of CHD, we calculated CHD risks on a population-based sample before and after implementation. The effect of the policies was modelled in three ways, based on projected changes: (i) in plasma lipid profiles; (ii) in lipid and inflammatory biomarkers; and (iii) the results of prospective cohort studies. We also estimated the present economic value of DALYs and associated health-care costs of coronary heart disease averted. Findings We estimated that projected changes in lipid profile would avert 301 deaths, 1066 acute CHD events, 5237 DALYs and 17 million United States dollars (US$) in health-care costs annually. Based on the adverse effects of TFA intake reported in prospective cohort studies, 1517 deaths, 5373 acute CHD events, 26 394 DALYs and US$ 87 million would be averted annually. Conclusion Even under the most conservative scenario, reduction of TFA intake had a substantial effect on public healt