The LionHeart LVD-2000: a completely implanted left ventricular assist device for chronic circulatory support

Left ventricular assist devices: yesterday, today, and tomorrow

The shortcomings of expense, power requirements, infection, durability, size, and blood trauma of current durable LVADs have been recognized for many years. The LVADs of tomorrow aspire to be fully implantable, durable, mitigate infectious risk, mimic the pulsatile nature of the native cardiac cycle, as well as minimize bleeding and thrombosis. Power draw, battery cycle lifespan and trans-cutaneous energy transmission remain barriers to completely implantable systems. Potential solutions include decreases in pump electrical draw, improving battery lifecycle technology and better trans-cutaneous energy transmission, potentially from Free-range Resonant Electrical Energy Delivery. In this review, we briefly discuss the history of LVADs and summarize the LVAD devices in the development pipeline seeking to address these issues.

Developments and Challenges in Durable Ventricular Assist Device Technology: A Comprehensive Review with a Focus on Advancements in China

Heart transplantation is currently the most effective treatment for end-stage heart failure; however, the shortage in donor hearts constrains the undertaking of transplantation. Mechanical circulatory support (MCS) technology has made rapid progress in recent years, providing diverse therapeutic options and alleviating the dilemma of donor heart shortage. The ventricular assist device (VAD), as an important category of MCS, demonstrates promising applications in bridging heart transplantation, destination therapy, and bridge-to-decision. VADs can be categorized as durable VADs (dVADs) and temporary VADs (tVADs), according to the duration of assistance. With the technological advancement and clinical application experience accumulated, VADs have been developed in biocompatible, lightweight, bionic, and intelligent ways. In this review, we summarize the development history of VADs, focusing on the mechanism and application status of dVADs in detail, and further discuss the research progress and use of VADs in China.

Fluid-structure interaction modelling of a positive-displacement Total Artificial Heart

For those suffering from end-stage biventricular heart failure, and where a heart transplantation is not a viable option, a Total Artificial Heart (TAH) can be used as a bridge to transplant device. The Realheart TAH is a four-chamber artificial heart that uses a positive-displacement pumping technique mimicking the native heart to produce pulsatile flow governed by a pair of bileaflet mechanical heart valves. The aim of this work was to create a method for simulating haemodynamics in positive-displacement blood pumps, using computational fluid dynamics with fluid-structure interaction to eliminate the need for pre-existing in vitro valve motion data, and then use it to investigate the performance of the Realheart TAH across a range of operating conditions. The device was simulated in Ansys Fluent for five cycles at pumping rates of 60, 80, 100 and 120 bpm and at stroke lengths of 19, 21, 23 and 25 mm. The moving components of the device were discretised using an overset meshing approach, a novel blended weak-strong coupling algorithm was used between fluid and structural solvers, and a custom variable time stepping scheme was used to maximise computational efficiency and accuracy. A two-element Windkessel model approximated a physiological pressure response at the outlet. The transient outflow volume flow rate and pressure results were compared against in vitro experiments using a hybrid cardiovascular simulator and showed good agreement, with maximum root mean square errors of 15% and 5% for the flow rates and pressures respectively. Ventricular washout was simulated and showed an increase as cardiac output increased, with a maximum value of 89% after four cycles at 120 bpm 25 mm. Shear stress distribution over time was also measured, showing that no more than [Formula: see text]% of the total volume exceeded 150 Pa at a cardiac output of 7 L/min. This study showed this model to be both accurate and robust across a wide range of operating points, and will enable fast and effective future studies to be undertaken on current and future generations of the Realheart TAH.

Treatment of Advanced Heart Failure-Focus on Transplantation and Durable Mechanical Circulatory Support: What Does the Future Hold?

Heart transplantation (HTx) is the treatment of choice in patients with late-stage advanced heart failure (Advanced HF). Survival rates 1, 5, and 10 years after transplantation are 87%, 77%, and 57%, respectively, and the average life expectancy is 9.16 years. However, because of the donor organ shortage, waiting times often exceed life expectancy, resulting in a waiting list mortality of around 20%. This review aims to provide an overview of current standard, recent advances, and future developments in the treatment of Advanced HF with a focus on long-term mechanical circulatory support and HTx.

Systems of conductive skin for power transfer in clinical applications

The primary aim of this article is to review the clinical challenges related to the supply of power in implanted left ventricular assist devices (LVADs) by means of transcutaneous drivelines. In effect of that, we present the preventive measures and post-operative protocols that are regularly employed to address the leading problem of driveline infections. Due to the lack of reliable wireless solutions for power transfer in LVADs, the development of new driveline configurations remains at the forefront of different strategies that aim to power LVADs in a less destructive manner. To this end, skin damage and breach formation around transcutaneous LVAD drivelines represent key challenges before improving the current standard of care. For this reason, we assess recent strategies on the surface functionalization of LVAD drivelines, which aim to limit the incidence of driveline infection by directing the responses of the skin tissue. Moreover, we propose a class of power transfer systems that could leverage the ability of skin tissue to effectively heal short diameter wounds. In this direction, we employed a novel method to generate thin conductive wires of controllable surface topography with the potential to minimize skin disruption and eliminate the problem of driveline infections. Our initial results suggest the viability of the small diameter wires for the investigation of new power transfer systems for LVADs. Overall, this review uniquely compiles a diverse number of topics with the aim to instigate new research ventures on the design of power transfer systems for IMDs, and specifically LVADs.

Current perspectives on mechanical circulatory support

Mechanical circulatory support gained a significant value in the armamentarium of heart failure therapy because of the increased awareness of the prevalence of heart failure and the tremendous advances in the field of mechanical circulatory support during the last decades. Current device technologies already complement a heart transplant as the gold standard of treatment for patients with end-stage heart failure refractory to conservative medical therapy. This article reviews important aspects of mechanical circulatory support therapy and focuses on currently debated issues.

Advanced heart failure with reduced ejection fraction

Patients suffering advanced heart failure with reduced ejection fraction (HFrEF) account for a large portion of patients admitted to hospitals worldwide. Mortality and 30-day readmission rates for HFrEF are now a focus of value-based payment models, making management of this disease a priority for hospitals, physicians, and payers alike. Angiotensin-converting enzyme inhibitors have been the cornerstone of therapy for decades. However, with treatment, the prognosis for patients with advanced HFrEF remains poor. Fortunately, advances in medical therapy and mechanical support offer some patients improvement in both survival and quality of life. We review advances in short- and long-term mechanical support and explore changes to organ allocation for cardiac transplantation. In addition, we provide a guide to facilitate appropriate referral to an advanced heart failure team.

Review and reflections about pulsatile ventricular assist devices from history to future: concerning safety and low haemolysis-still needed

Since the first use of a ventricular assist device in 1963 many extracorporeal and implantable pulsatile blood pumps have been developed. After the invention of continuous flow blood pumps the implantable pulsatile pumps are not available anymore. The new rotary pumps spend a better quality of life because many of the patients can go home. Nevertheless, the extracorporeal pulsatile pumps have some advantages. They are low-cost systems, produce less haemolysis and heart-recovery can be tested easily. Pump failure is easy to realize because the pumps can be observed visually. Pump exchange can be done easily without any chirurgic surgery. As volume displacement pumps they can produce high blood pressure, so they are the only ones suitable for pediatric patients. Therefore, they are indispensable for clinical use today and in the future. In this work, nearly all pulsatile blood pumps used in clinical life are described.

A review of implantable pulsatile blood pumps: Engineering perspectives

It has been reported that long-term use of continuous-flow mechanical circulatory support devices (CF-MCSDs) may induce complications associated with diminished pulsatility. Pulsatile-flow mechanical circulatory support devices (PF-MCSDs) have the potential of overcoming these shortcomings with the advance of technology. In order to promote in-depth understanding of PF-MCSD technology and thus encourage future mechanical circulatory support device innovations, engineering perspectives of PF-MCSD systems, including mechanical designs, drive mechanisms, working principles, and implantation strategies, are reviewed in this article. Some emerging designs of PF-MCSDs are introduced, and possible elements for next-generation PF-MCSDs are identified.

Feasibility of a Post-Auricle Wireless Power System for Pediatric Mechanical Circulatory Support Pumps

Heart failure (HF) affects approximately 12,000-35,000 children each year in the United States. The development of blood pumps has provided circulatory support for many adults suffering with HF until they receive a heart transplant. However, while the development of blood pumps for adults has led to fullyimplantable continuous flow devices, blood pump technology for children has lagged significantly behind. One area for improving blood pump implantability in children is the use of wireless powering transfer systems (WPTS). These systems eliminate the power cord connecting the implanted blood pump to the external power supply. In adults, WPTS have decreased the number of power cord-related infections and have improved patient outcomes after pump implantation. Unfortunately, the components of these wireless systems are too large for children. In this paper we describe the preliminary work to develop a fully implantable WPTS specifically designed to power the Jarvik 2000 Child. Specifically, we design planar coils 36 um in thickness to be implanted in behind-the-ear fashion. An amplifier and rectifier circuit were also built to provide 15.7V and 0.5A of voltage and current to the pump.

Left Ventricular Assist Devices - A State of the Art Review

Cardiovascular diseases are the leading cause of mortality rates throughout the world. Next to an insufficient number of healthy donors, this has led to increasing numbers of patients on heart transplant waiting lists with prolonged waiting times. Innovative technological advancements have led to the production of ventricular assist devices that play an increasingly important role in end stage heart failure therapy. This review is intended to provide an overview of current implantable left ventricular assist devices, different design concepts and implantation techniques. Challenges such as infections and thromboembolic events that may occur during LVAD implantations have also been discussed.

Advancements in mechanical circulatory support for patients in acute and chronic heart failure

Cardiogenic shock (CS) continues to have high mortality and morbidity despite advances in pharmacological, mechanical, and reperfusion approaches to treatment. When CS is refractory to medical therapy, percutaneous mechanical circulatory support (MCS) should be considered. Acute MCS devices, ranging from intra-aortic balloon pumps (IABPs) to percutaneous temporary ventricular assist devices (VAD) to extracorporeal membrane oxygenation (ECMO), can aid, restore, or maintain appropriate tissue perfusion before the development of irreversible end-organ damage. Technology has improved patient survival to recovery from CS, but in patients whom cardiac recovery does not occur, acute MCS can be effectively utilized as a bridge to long-term MCS devices and/or heart transplantation. Heart transplantation has been limited by donor heart availability, leading to a greater role of left ventricular assist device (LVAD) support. In patients with biventricular failure that are ineligible for LVAD implantation, further advancements in the total artificial heart (TAH) may allow for improved survival compared to medical therapy alone. In this review, we discuss the current state of acute and durable MCS, ongoing advances in LVADs and TAH devices, improved methods of durable MCS implantation and patient selection, and future MCS developments in this dynamic field that may allow for optimization of HF treatment.

Anesthetic and Perioperative Considerations in Patients Undergoing Placement of Totally Implantable Replacement Hearts

The recent successful implantation of the AbioCor im plantable replacement heart at the Rudd Heart-Lung Institute, Jewish Hospital, Louisville, KY, has renewed clinical interest in the use of the mechanical replace ment heart as therapy for intractable heart failure. Al though the number of orthotopic heart transplants has plateaued in the past decade, the number of patients requiring transplantation continues to increase. This supply/demand discrepancy continues to be the main catalyst for the research and development of other therapies for the failing heart. This review addresses perioperative considerations, monitoring modalities, and perioperative therapeutic interventions that may help guide the cardiac anesthesiologist through the challenges presented by implantation of total replace ment hearts in end-stage cardiac patients.

Mechanical circulatory support: state of the art and future perspectives

Mechanical circulatory support (MCS) has been viewed, until recently, as a rescue therapy to be applied when all else fails. Not surprisingly, this has resulted in suboptimal outcomes. Fortunately, the perseverance of a few dedicated groups has produced improved outcomes and the concept of MCS as an elective therapy is now steadily gaining acceptance. This is particularly true in the postcardiotomy setting, where a large number of new options are now available. The recently completed REMATCH study has demonstrated the feasibility and efficacy of permanent MCS as a therapy for end-stage heart failure, despite a high rate of device complications. Donor availability is decreasing and biological solutions will not be available for many years. New generation implantable rotary pumps, a fully implantable left ventricular assist device and a total artificial heart are all undergoing clinical evaluation, and several new exciting designs are in preclinical evaluation. A new paradigm for the treatment of terminal heart failure is emerging, where an unpredictable and expensive medically managed death in an intensive care unit setting is being exchanged for a more predictable high-cost, front-loaded therapy with management from the outpatient clinic. The perfusionist community has much to contribute to this emerging life support field, not only in the perioperative period, but also in providing ongoing technical support to hospital staff, recipients and their families.

Mechanical Approach in the Management of Advanced Acute and Chronic Heart Failure

Despite the progress in medical therapy, advanced heart failure (AHF) remains a global epidemic with high morbidity and mortality. Novel cardiac support strategies such as pharmacologic agents, mechanical circulatory support (MCS), and cell- or matrix-based therapies are promising for these patients. The indications, types, and timing of MCS implantation depend to a large extent on the presentation, clinical status of the patient, underlying etiology, and long-term prospects. The presence or absence of end-organ damage has a significant impact on prognosis following MCS initiation. Although many patients with acute AHF may have end-organ damage, their prospect of recovery, once appropriate therapy is instituted, is better than for patients who had AHF for longer periods of time. We consider the multidisciplinary approaches used for the management of AHF and the novel cardiac support strategies (eg, MCS). Appropriate selection of patient, device, time, and end point is essential for better outcomes.

The Use of Fluid Mechanics to Predict Regions of Microscopic Thrombus Formation in Pulsatile VADs

We compare the velocity and shear obtained from particle image velocimetry (PIV) and computational fluid dynamics (CFD) in a pulsatile ventricular assist device (VAD) to further test our thrombus predictive methodology using microscopy data from an explanted VAD. To mimic physiological conditions in vitro, a mock circulatory loop is used with a blood analog that matched blood's viscoelastic behavior at 40% hematocrit. Under normal physiologic pressures and for a heart rate of 75 bpm, PIV data is acquired and wall shear maps are produced. The resolution of the PIV shear rate calculations are tested using the CFD and found to be in the same range. A bovine study, using a model of the 50 cc Penn State V-2 VAD, for 30 days at a constant beat rate of 75 beats per minute (bpm) provides the microscopic data whereby after the 30 days, the device is explanted and the sac surface analyzed using scanning electron microscopy (SEM) and, after immunofluorescent labeling for platelets and fibrin, confocal microscopy. Areas are examined based on PIV measurements and CFD, with special attention to low shear regions where platelet and fibrin deposition are most likely to occur. Data collected within the outlet port in a direction normal to the front wall of the VAD shows that some regions experience wall shear rates less than 500 s^-1, which increases the likelihood of platelet and fibrin deposition. Despite only one animal study, correlations between PIV, CFD, and in vivo data show promise. Deposition probability is quantified by the thrombus susceptibility potential, a calculation to correlate low shear and time of shear with deposition.

Impact of adverse events on ventricular assist device outcomes

Left ventricular assist devices have been proven to be superior to medical therapy for advanced heart failure patients awaiting heart transplantation and viable alternatives to transplantation for destination therapy patients. Improvements in the design of ventricular assist devices have been rewarded by a decrease in adverse events and an increase in survival. Despite significant progress, even the latest generation left ventricular assist devices are burdened by a significant long-term adverse events profile that will increasingly challenge physicians as patients survive longer on implantable mechanical circulatory support. In this review, we analyze the impact of long-term adverse events on clinical outcomes in the major trials of continuous flow left ventricular assist devices. We discuss several of the more pertinent and interesting adverse events, examine their potential causes, and explore their future implications.

Mechanical circulatory support for heart failure: past, present and a look at the future

Heart transplantation remains the gold standard for long-term cardiac replacement, but a shortage of donor organs will always limit this option. For both transplant-eligible and noneligible patients, advances in mechanical circulatory support have revolutionized the options for the management of end-stage heart failure, and this technology continues to bring us closer to a true alternative to heart transplantation. This review provides a perspective on the past, present and future of mechanical circulatory support and addresses the changes in technology, patient selection and management strategies needed to have this therapy fully embraced by the heart failure community, and perhaps replace heart transplantation either as the therapy of choice or as a strategy by which to delay transplantation in younger patients.

Miniaturization of mechanical circulatory support systems

Heart failure (HF) is increasing worldwide and represents a major burden in terms of health care resources and costs. Despite advances in medical care, prognosis with HF remains poor, especially in advanced stages. The large patient population with advanced HF and the limited number of donor organs stimulated the development of mechanical circulatory support (MCS) devices as a bridge to transplant and for destination therapy. However, MCS devices require a major operative intervention, cardiopulmonary bypass, and blood component exposure, which have been associated with significant adverse event rates, and long recovery periods. Miniaturization of MCS devices and the development of an efficient and reliable transcutaneous energy transfer system may provide the vehicle to overcome these limitations and usher in a new clinical paradigm in heart failure therapy by enabling less invasive beating heart surgical procedures for implantation, reduce cost, and improve patient outcomes and quality of life. Further, it is anticipated that future ventricular assist device technology will allow for a much wider application of the therapy in the treatment of heart failure including its use for myocardial recovery and as a platform for support for cell therapy in addition to permanent long-term support.

A thrombus susceptibility comparison of two pulsatile Penn State 50 cc left ventricular assist device designs

Left ventricular assist devices (LVADs) have proven successful as bridge to transplant devices for patients awaiting donor organs. While survival rates continue to increase, destination therapy remains hindered by thrombus formation within the device. Research has shown that thrombosis is correlated to the fluid dynamics within the device and may be a result of sustained shear rates below 500 s(-1) on the polyurethane blood sac used in the Penn State pulsatile LVAD. Particle image velocimetry is used to compare flow within two 50 cc LVAD designs to assess fluid patterns and quantify wall shear rates in regions known from in vivo studies to be susceptible to thrombus formation. The two designs differ in their front face geometry. The V-1 model has an outward-facing "dome" whereas the face of the V-2 model is flat. A thrombus susceptibility metric, which uses measured wall shear rates and exposure times, was applied to objectively compare pump designs over the entire cardiac cycle. For each design, there are regions where wall shear rates remained below 500 s(-1) for the entire cardiac cycle resulting in high thrombus susceptibility potential. Results of this study indicate that the V-2 device had an overall lower propensity for thrombus formation in the current region of interest.

A fluid dynamics study in a 50 cc pulsatile ventricular assist device: influence of heart rate variability

Although left ventricular assist devices (LVADs) have had success in supporting severe heart failure patients, thrombus formation within these devices still limits their long term use. Research has shown that thrombosis in the Penn State pulsatile LVAD, on a polyurethane blood sac, is largely a function of the underlying fluid mechanics and may be correlated to wall shear rates below 500 s(-1). Given the large range of heart rate and systolic durations employed, in vivo it is useful to study the fluid mechanics of pulsatile LVADs under these conditions. Particle image velocimetry (PIV) was used to capture planar flow in the pump body of a Penn State 50 cubic centimeters (cc) LVAD for heart rates of 75-150 bpm and respective systolic durations of 38-50%. Shear rates were calculated along the lower device wall with attention given to the uncertainty of the shear rate measurement as a function of pixel magnification. Spatial and temporal shear rate changes associated with data collection frequency were also investigated. The accuracy of the shear rate calculation improved by approximately 40% as the resolution increased from 35 to 12 μm/pixel. In addition, data collection in 10 ms, rather than 50 ms, intervals was found to be preferable. Increasing heart rate and systolic duration showed little change in wall shear rate patterns, with wall shear rate magnitude scaling by approximately the kinematic viscosity divided by the square of the average inlet velocity, which is essentially half the friction coefficient. Changes in in vivo operating conditions strongly influence wall shear rates within our device, and likely play a significant role in thrombus deposition. Refinement of PIV techniques at higher magnifications can be useful in moving towards better prediction of thrombosis in LVADs.

Contemporary management and research directions in advanced heart failure: where are we going?

Advanced heart failure (AHF) is not a uniform disorder, but is rather a heterogeneous group of patients with varying clinical presentations and definitions. It is growing in magnitude and represents a major public health problem. Herein we describe contemporary care of the patient with AHF, novel medical therapies, and mechanical circulatory assist devices. We speculate where progress has been made and where the major gaps in knowledge remain. Clearly, there is ample opportunity for research and discovery to further advance the care of these very sick patients.

Transcutaneous energy transmission for mechanical circulatory support systems: history, current status, and future prospects

A totally implantable mechanical circulatory support system would be very desirable for destination therapy. However, implanting all components of a pulsatile total artificial heart (TAH) or left ventricular assist device (LVAD) is complex because of the requirement for a continuous electrical power supply and the need for volume compensation. Implantable compliance chambers were developed for early LVAD designs, and although they functioned properly during initial laboratory tests, air loss by diffusion and the development of fibrous tissue around the sac eventually rendered them ineffective. Because these problems have not yet been overcome, volume displacement LVADs are currently designed with either a direct communication to an external drive console or an atmospheric vent. Transcutaneous energy transmission systems (TETSs) were also developed, but because the skin was being penetrated for volume compensation, it seemed more efficient to transmit electrical power through wires incorporated into the venting apparatus. More recently, TETSs were used clinically for both a pulsatile TAH and LVAD in a small number of patients, but for reasons unrelated to the TETS, neither of these devices is presently in use. Because the newer continuous-flow LVADs do not require a compliance chamber, they present a potential future application for TETS technology, because infections of the percutaneous tube continue to be one of the most important limitations of long-term circulatory support. A totally implantable LVAD with an incorporated TETS for destination therapy could become an important advance in the treatment of end-stage heart failure.

Management strategies for stage-D patients with acute heart failure

Heart Failure (HF) accounted for 3.4 million ambulatory visits in 2000. Current guidelines from the American Heart Association/American College of Cardiology, the Heart Failure Society of America, and the International Society for Heart & Lung Transplantation recommend aggressive pharmacologic interventions for patients with HF. This may include a combination of diuretics, Angiotensin Converting Enzyme inhibitors, beta-blockers, angiotensin receptor blockers, aldosterone antagonists, and digoxin. Nitrates and hydralazine are also indicated as part of standard therapy in addition to beta-blockers and Angiotensin Converting Enzyme inhibitors, especially but not exclusively, for African Americans with left ventricular (LV) systolic dysfunction. For those with acute decompensated HF, additional treatment options include recombinant human B-type natriuretic peptide, and in the future possible newer agents not yet approved for use in the U.S., such as Levosimendan. Medical devices for use in patients with advanced HF include LV assist devices, cardiac resynchronization therapy, and implantable cardioverter defibrillators. For refractory patients, heart transplantation, the gold-standard surgical intervention for the treatment of refractory HF, may be considered. Newer surgical options such as surgical ventricular restoration may be considered in select patients.

Destination therapy: does progress depend on left ventricular assist device development?

The role of therapy using mechanical circulatory support devices has evolved rapidly over the last two decades. New developments in the field achieved smaller adverse events, but, currently, only minor improvements in survival were observed in published observational data. The authors discuss the development of mechanical circulatory support devices as a "destination therapy" option for patients who have end-stage heart failure and are ineligible for heart transplantation as it relates to left ventricular assist device development.

Development of mechanical circulatory support devices at the University of Tokyo

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

Hemodynamic performance in-vivo of a new ventricular assist device

Nowadays, circulatory support has become a common practice in medicine and a standard in the treatments of Cardio Vascular Disease (CVD). A new Pneumatic Ventricular Assist Device (VAD) has been developed in México City. This paper shows the first results of acute in-vivo trials, intended to verify the new system for providing physiological flows and pressures. Two VADs were implanted to as right (RVAD), left (LVAD) support in a 65 kg pig. The support time was 20 minutes with RVAD, 20 minutes with LVAD and 20 minutes with Biventricular (BiVAD). The VAD proved its capability to maintain physiological parameters during the support time. We are satisfied with the results of this trial, and we believe this study will ascertain the first step on the next phase of invivo trials.

Infection in ventricular assist devices: the role of biofilm

Ventricular assist devices improve hemodynamics in patients with heart failure, but like most implantable medical devices, they are prone to infection; organisms that are adept at forming biofilm cause most of these. Biofilm confers many advantages to the organisms, including protecting them against natural host defenses and antimicrobial therapies. This review will focus on the mechanisms of biofilm formation, including quorum sensing and subsequent changes in microbial gene and protein expression. Novel therapies targeting these processes, as well as improvements in device design and clinical management, have begun to emerge and will aid in the management of these recalcitrant infections.

Report of the First U.S. Patient Successfully Supported Long Term With the LionHeart Completely Implantable Left Ventricular Assist Device System

We report our first successful long-term survivor in the United States with the LionHeart (Arrow International, Inc., Reading, PA) completely implantable left ventricular assist device system. The patient was initially deemed a poor candidate for cardiac transplantation and had inotrope-dependent, end-stage cardiac failure. The patient was supported for 13 months with this system. During this period of support, the patient returned to independent living and derived obvious benefits toward his daily activities with the completely implanted system. The device proved to be reliable during this period of support. Through lifestyle modification, the patient was ultimately deemed an appropriate candidate for heart transplantation and ultimately received successful transplantation.

MagScrew TAH: an update

The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions. The passively filling pump uses a left master alternate left and right ejection control mode and has a Starling law-like response to venous pressure. The in vitro tests documented excellent hydraulic pump performance with high device output of over 9 l/min at left atrial pressures below 12 mm Hg. Atrial balance was well maintained under all test conditions. The in vivo tests demonstrated good biocompatibility without use of anticoagulant therapy. Experimental durations have ranged between 0 and 92 days. Postexplant evaluation of tissue samples did not reveal any sign of thromboembolic events or tissue damage due to device operation.

An Intelligent Remote Monitoring System for Artificial Heart

A web-based database system for intelligent remote monitoring of an artificial heart has been developed. It is important for patients with an artificial heart implant to be discharged from the hospital after an appropriate stabilization period for better recovery and quality of life. Reliable continuous remote monitoring systems for these patients with life support devices are gaining practical meaning. The authors have developed a remote monitoring system for this purpose that consists of a portable/desktop monitoring terminal, a database for continuous recording of patient and device status, a web-based data access system with which clinicians can access real-time patient and device status data and past history data, and an intelligent diagnosis algorithm module that noninvasively estimates blood pump output and makes automatic classification of the device status. The system has been tested with data generation emulators installed on remote sites for simulation study, and in two cases of animal experiments conducted at remote facilities. The system showed acceptable functionality and reliability. The intelligence algorithm also showed acceptable practicality in an application to animal experiment data.

The Status of Failure and Reliability Testing of Artificial Blood Pumps

Artificial blood pumps are today's most promising bridge-to-transplant, bridge-to-recovery, and destination therapy solutions for patients with congestive heart failure. There is a critical need for increased reliability and safety as the next generation of artificial blood pumps approach final development for long-term destination therapy. To date, extensive failure and reliability studies of these devices are considered intellectual property and thus remain unpublished. Presently, the Novacor N100PC, Thoratec VAD, and HeartMate LVAS (IP and XVE) comprise the only four artificial blood pumps commercially available for the treatment of congestive heart failure in the United States. The CardioWest TAH recently received premarket approval from the US Food and Drug Administration. With investigational device exemptions, the AB-180, AbioCor, LionHeart, DeBakey, and Flowmaker are approved for clinical testing. Other blood pumps, such as the American BioMed-Baylor TAH, CorAide, Cleveland Clinic-Nimbus TAH, HeartMate III, Hemadyne, and MagScrew TAH are currently in various stages of mock loop and animal testing, as indicated in published literature. This article extensively reviews in vitro testing, in vivo testing, and the early clinical testing of artificial blood pumps in the United States, as it relates to failure and reliability. This detailed literature review has not been published before and provides a thorough documentation of available data and testing procedures regarding failure and reliability of these various pumps.

Left ventricular assist devices for the treatment of congestive heart failure

The mainstay of heart failure therapy is aggressive medical management with consideration of resynchronization therapy and automatic implantable cardioverter-defibrillator. This is best done with the support of a multidisciplinary team. Transplantation, when possible, remains the therapy of choice for patients who are refractory to medical therapy. Other options short of left ventricular assist device (LVAD) that should be considered include revascularization, mitral valve repair, and left ventricular remodeling procedures. LVAD therapy as a bridge to transplantation should be considered in patients with heart failure who are clinically deteriorating while on the transplant waiting list. This should be initiated prior to the onset of irreversible end-organ damage. In nontransplant candidates, an LVAD can be considered as an alternative to transplantation (destination therapy). However, cost and the availability of expertise continue to limit this therapy to quaternary care and research institutions.

Rotary Blood Pumps for Cardiac Assistance: A "Must"?

Ventricular Assist Devices (VADs) were developed following the observation that most end-stage heart failure patients only required left heart support for survival. The trend toward left VAD implantation instead of a TAH has actually contributed to the development of nonpulsatile rotational devices. This article intends to evaluate the current and future technology of continuous flow pumps. Various issues pertaining to the long-term effects of continuous blood flow, biocompatibility of axial flow pumps, and the safety and reliability of such devices need to be addressed. Some of the advantages of rotary blood pumps include their small size, ease of implantation, and encouraging low infection rates. Certain issues such as automatic flow control, device components durability, and hemocompatibility remain unresolved. The quest for an ideal device combining optimal efficiency, ease of anatomical fit, and perfect bioacceptance, continues. Rotary blood pumps are not yet a "must."

Ventricular assist devices as destination therapy

The prospects for long-term mechanical circulatory support are improving. Axial flow pumps are a promising competitor to pulsatile first-generation LVADs, although the two may serve different patient populations. Centrifugal pumps are in the development phase and seem to require less anticoagulation. Clinical experience has established the safety of diminished pulse pressure circulation, and mechanical unloading appears to promote recovery of the native left ventricle. Under these circumstances, true left ventricular assist is preferable to ventricular replacement and detailed medical management improves patient outcomes. Further clinical trials of destination therapy are indicated and must use more reliable blood pumps implanted before terminal decline into multiorgan failure.