Adverse Events in Total Artificial Heart for End-Stage Heart Failure: Insight From the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE)

Background and Objectives

Real-world clinical data, outside of clinical trials and expert centers, on adverse events related to the use of SyncCardia total artificial heart (TAH) remain limited. We aim to analyze adverse events related to the use of SynCardia TAH reported to the Food and Drug Administration (FDA)'s Manufacturers and User Defined Experience (MAUDE) database.

Methods

We reviewed the FDA's MAUDE database for any adverse events involving the use of SynCardia TAH from 1/01/2012 to 9/30/2020. All the events were independently reviewed by three physicians.

Results

A total of 1,512 adverse events were identified in 453 "injury and death" reports in the MAUDE database. The most common adverse events reported were infection (20.2%) and device malfunction (20.1%). These were followed by bleeding events (16.5%), respiratory failure (10.1%), cerebrovascular accident (CVA)/other neurological dysfunction (8.7%), renal dysfunction (7.5%), hepatic dysfunction (2.2%), thromboembolic events (1.8%), pericardial effusion (1.8%), and hemolysis (1%). Death was reported in 49.4% of all the reported cases (n=224/453). The most common cause of death was multiorgan failure (n=73, 32.6%), followed by CVA/other non-specific neurological dysfunction (n=44, 19.7%), sepsis (n=24, 10.7%), withdrawal of support (n=20, 8.9%), device malfunction (n=11, 4.9%), bleeding (n=7, 3.1%), respiratory failure (n=7, 3.1%), gastrointestinal disorder (n=6, 2.7%), and cardiomyopathy (n=3, 1.3%).

Conclusions

Infection was the most common adverse event following the implantation of TAH. Most of the deaths reported were due to multiorgan failure. Early recognition and management of any possible adverse events after the TAH implantation are essential to improve the procedural outcome and patient survival.

Effects of biventricular shunt on pump characteristics in a maglev total artificial heart

Severe left ventricular failure can progress to right ventricular failure, necessitating alternatives to heart transplantation, such as total artificial heart (TAH) treatment. Conventional TAHs encounter challenges associated with miniaturization and hemocompatibility owing to their reliance on mechanical valves and bearings. A magnetically levitated TAH (IB-Heart) was developed, utilizing a magnetic bearing. The IB-Heart features a distinctive biventricular shunt channel situated between the flow paths of the left and right centrifugal blood pumps, simplifying and miniaturizing its control system. However, the impact of these shunt channels remains underexplored. This study aimed to investigate the effects of shunt flow on pump characteristics and assess the IB-Heart's potential to regulate flow balance between systemic and pulmonary circulation. At a rotational speed of 2000 rpm and flow rate range of 0-10 L/min, shunt flow exhibited a minor impact, with a 1.4 mmHg (1.3%) effect on pump characteristics. Shunt flow variation of about 0.13 L/min correlated with a 10 mmHg pressure difference between the pumps' afterload and preload conditions. This variance was linked to changes in the inlet flow rates of the left and right pumps, signifying the ventricular shunt structure's capacity to mirror the function of an atrial shunt in alleviating pulmonary congestion. The IB-Heart's ventricular shunt structure enables passive regulation of left-right flow balance. The findings establish a fundamental technical groundwork for the development of IB-Hearts and TAHs with similar shunt structures. The innovative coupling of centrifugal pumps and the resultant effects on flow dynamics contribute to the advancement of TAH technology.

Functional regeneration at the blood-biomaterial interface

The use of cardiovascular implants is commonplace in clinical practice. However, reproducing the key bioactive and adaptive properties of native cardiovascular tissues with an artificial replacement is highly challenging. Exciting new treatment strategies are under development to regenerate (parts of) cardiovascular tissues directly in situ using immunomodulatory biomaterials. Direct exposure to the bloodstream and hemodynamic loads is a particular challenge, given the risk of thrombosis and adverse remodeling that it brings. However, the blood is also a source of (immune) cells and proteins that dominantly contribute to functional tissue regeneration. This review explores the potential of the blood as a source for the complete or partial in situ regeneration of cardiovascular tissues, with a particular focus on the endothelium, being the natural blood-tissue barrier. We pinpoint the current scientific challenges to enable rational engineering and testing of blood-contacting implants to leverage the regenerative potential of the blood.

COVID-19 in a patient implanted with a total artificial heart: a case report

Background

The coronavirus disease 2019 (COVID-19) was first identified in December 2019 and is currently still a public health issue affecting millions of people worldwide. Heart failure patients are known to be at higher risk of morbidity and mortality in this case. Yet, few data exist concerning COVID-19 among patients with a left ventricular assistance device, and even less among those with a total artificial heart (TAH).

Case summary

A 27-year-old man with Marfan syndrome underwent prophylactic ascending aorta replacement. Shortly after surgery completion, he developed refractory cardiogenic shock with biventricular dysfunction leading to veno-arterial extracorporeal membrane oxygenation (VA-ECMO) implantation. In the context of no appropriate eligible donor during the following 10 days while waiting on the heart transplantation list, the patient was scheduled for a TAH as a bridge to transplantation. Meanwhile, he developed an acute respiratory distress syndrome secondary to SARS-CoV-2. The patient was successfully treated with corticosteroids, prone positioning and mechanical ventilation, and heart transplantation occurred 5 weeks after COVID-19 onset.

Discussion

Here, we report the first case of a patient presenting with COVID-19 infection following TAH implantation in a bridge to transplantation. We highlight that (i) cardiogenic shock patients simultaneously infected by COVID-19 should be treated instantly with all-time available technology to ensure best outcomes, including TAH and prone positioning, (ii) heart transplantation safety 5 weeks after COVID-19 onset.

State-of-the-art review on management of end-stage heart failure in amyloidosis: transplant and beyond

Cardiac involvement occurs in light-chain (AL), transthyretin wild-type (wtATTR), and hereditary (hATTR) amyloidosis; other types of amyloidosis account for < 5% of all cardiac amyloidosis (CA). CA can present subclinically on screening, insidiously with symptoms such as exertional dyspnea, or abruptly as cardiogenic shock. Initially, CA patients were thought to be poor candidates for transplant due to short long-term survival; however, there is a marked improvement in heart and multi-organ transplant outcomes over the past 10 years with newer treatments and improvements in support with temporary and durable mechanical circulatory support while awaiting transplant. Patients with AL CA were reported to have worse post-OHT outcomes than patients with ATTR CA, but this gap is quickly closing with improved patient selection, novel chemotherapeutics, and perhaps with selected use of bone marrow transplantation. Waitlist mortality and transplantation rates have markedly improved for CA after the United Network for Organ Sharing (UNOS) policy change in October 2018. In this review, we will evaluate contemporary data from the last 5 years on advances in the field of transplantation and mechanical circulatory support in this patient population.

Anticoagulation in syncardia total artificial heart recipients: anti-factor Xa or activated partial thromboplastin time?

Although the activated partial thromboplastin time (aPTT) has historically been the method of choice for anticoagulation monitoring in patients undergoing mechanical circulatory support with intravenous unfractionated heparin, it is being progressively superseded by the anti-factor Xa (anti-Xa) method. A retrospective single-arm, single-centre analysis of 20 patients who underwent total artificial heart implantation entailed simultaneous determinations of aPTT and anti-Xa. Agreement between these parameters was assessed using the Bland-Altman method. Despite a positive correlation between aPTT and anti-Xa, normal target ranges were poorly aligned: from 5th to 30th postoperative day, for anti-Xa values of 0.2 and 0.4 U/ml corresponding aPTT values were 52.1 and 65.2 s, 7.9 and 14.8 lower than predicted values, respectively. This was not associated with thromboembolic sequalae. It was not possible to demonstrate a significant relationship between the predictor variables (postoperative day; white blood cell count; C-reactive protein concentration; alanine transaminase and alkaline phosphatase level; bilirubin; haemoglobin; albumin and total protein concentration) and the agreement between aPTT and anti-Xa levels. In summary, when anti-Xa levels were used to guide anticoagulation therapy, corresponding aPTT levels were low with respect to target range. Methodology applied in this study is generalizable to other forms of mechanical circulatory support.

Elevated Circulating Stem Cells Level is Observed One Month After Implantation of Carmat Bioprosthetic Total Artificial Heart

The Aeson® total artificial heart (A-TAH) has been developed as a total heart replacement for patients at risk of death from biventricular failure. We previously described endothelialization of the hybrid membrane inside A-TAH probably at the origin of acquired hemocompatibility. We aimed to quantify vasculogenic stem cells in peripheral blood of patients with long-term A-TAH implantation. Four male adult patients were included in this study. Peripheral blood mononuclear cells were collected before A-TAH implantation (T0) and after implantation at one month (T1), between two and five months (T2), and then between six and twelve months (T3). Supervised analysis of flow cytometry data confirmed the presence of the previously identified Lin^-CD133⁺CD45^- and Lin^-CD34⁺ with different CD45 level intensities. Lin^-CD133⁺CD45^-, Lin^-CD34⁺CD45^- and Lin^-CD34⁺CD45⁺ were not modulated after A-TAH implantation. However, we demonstrated a significant mobilization of Lin^-CD34⁺CD45^dim (p = 0.01) one month after A-TAH implantation regardless of the expression of CD133 or c-Kit. We then visualized data for the resulting clusters on a uniform manifold approximation and projection (UMAP) plot showing all single cells of the live Lin^- and CD34⁺ events selected from down sampled files concatenated at T0 and T1. The three clusters upregulated at T1 are CD45^dim clusters, confirming our results. In conclusion, using a flow cytometry approach, we demonstrated in A-TAH-transplanted patients a significant mobilization of Lin^-CD34⁺CD45^dim in peripheral blood one month after A-TAH implantation. Using a flow cytometry approach, we demonstrated in A-TAH transplanted patients a significant mobilization of Lin^-CD34⁺CD45^dim in peripheral blood one month after A-TAH implantation. This cell population could be at the origin of newly formed endothelial cells on top of hybrid membrane in Carmat bioprosthetic total artificial heart.

Replacement of the right SynCardia® ventricle due to membrane rupture

Biventricular heart failure remains a major challenge and total artificial heart (TAH) (SynCardia Systems Inc., Tucson, AZ, USA) bear hurdles, in particular in long-term application. Ventricular membrane rupture of a TAH is a feared complication and often implies a fatal outcome. Hereby we present the first case of successful and effective replacement of a TAH right ventricle due to the membrane rupture.

Implanting the HeartMate 6 (total artificial heart)

The HeartMate 3 is a ventricular assist device that supports the heart with a centrifugal continuous flow. It contains a fully levitated rotor to minimize hemolysis and was initially designed as an apical intrapericardial implant. It can be used as a bridge to a transplant, to recovery, or to destination therapy. After we excise the ventricles, we implant 2 HeartMate 3 devices as a total artificial heart (HeartMate 6). The patient was 35 years old when the devices were implanted and had been diagnosed with Yamaguchi syndrome (apical hypertrophic cardiomyopathy) at 13 years of age. Being listed for a transplant was not an option due to secondary pulmonary hypertension. Furthermore, the conventional method of apically implanting a left ventricular assist device was not possible due to the underlying pathology. A HeartMate 6 implant as a bridge to transplant therapy was planned. Additionally, a CardioMEMS HF System was implanted to monitor the pulmonary artery pressure. The video tutorial provides step-by-step instructions for implanting 2 HeartMate 3 devices as a total artificial heart.

A systematic review of psychosocial design considerations for the next generation of mechanical circulatory support

BACKGROUND

Biomedical engineers are developing new mechanical circulatory support pumps. Clinicians are generating and analysing new evidence for their prescription and management. Industrial designers are generating usable solutions for wearable components and controllers. However, psychosocial considerations may be falling between the cracks of the three disciplines because of their multi-faceted nature.

OBJECTIVES

This article seeks to identify psychosocial needs raised in previous work, re-frame them as needs for future products and services, and discuss routes to solutions.

METHODS

SLR extracted 225 statements on psychosocial considerations from 42 included articles. 23 codes were inductively generated and applied to relevant datapoints. Codes were consolidated under 4 main themes and re-framed as solvable problems.

RESULTS

Identified themes: expanded remote care, improved multidisciplinary management tools, creating easier interactions; and extending patient engagement.

CONCLUSIONS

Design-driven methods have been used to solve analogous problems in other contexts and can address the identified psychosocial problems if implemented fully.

Feasibility of long-term continuous flow total heart replacement in calves

INTRODUCTION

Implementation of continuous flow (CF) technology in modern ventricular assist devices (VAD) has afforded a wealth of engineering and design advantages in the development of a total artificial heart (TAH). However, clinical application of CF has created a unique physiologic state, the consequences of which remain largely unknown. We sought to evaluate clinical and biochemical markers of end-organ function in calves supported with biventricular CF VADs for more than 30 days.

METHODS

Eight calves survived longer than 30 days following biventriculectomy and implantation of dual CF VADs. Four types of CF pumps were utilized for the study. Serial hematologic and biochemical profiles were drawn as markers for end-organ function, and hemodynamic data-including pump flows and intravascular pressures-were continuously monitored.

RESULTS

The eight calves survived an average of 58.8 days (range 30-92 days). Two of the calves were electively terminated at the conclusion of the study period, while the remaining animals were euthanized as a result of respiratory distress (n = 2) or impaired pump flows (n = 4). In each case, serial biochemical and hematologic values were suggestive of preserved end-organ function. Six animals successfully participated in treadmill exercise evaluations. No evidence of end-organ damage was encountered upon necropsy or histologic tissue analysis.

CONCLUSION

Biventricular CF VAD implantation permits a viable bovine CFTAH model capable of demonstrating long-term survival. After 30 days of completely nonpulsatile flow, cumulative hemodynamic, clinical, biochemical, and histological analyses were consistent with preserved end-organ function, suggesting previously unreported long-term feasibility of a CFTAH design.

A heart transplant after total artificial heart support: initial and long-term results

OBJECTIVES

At our centre, the SynCardia temporary Total Artificial Heart (TAH-t) (SynCardia Systems, LLC, Tucson, AZ, USA) is used to provide long-term support for patients with biventricular failure as a bridge to a transplant. However, a heart transplant (HT) after such support remains challenging. The aim of this retrospective study was to assess the immediate and long-term results following an HT in the cohort of patients who had a TAH-t implant.

METHODS

A total of 73 patients were implanted with the TAH-t between 1988 and 2019 in our centre. Of these 73 consecutive patients, 50 (68%) received an HT and are included in this retrospective analysis of prospectively collected data.

RESULTS

In the selected cohort, in-hospital mortality after an HT was 10% (n = 5). The median intensive care unit stay was 33 days (range 5-278). The median hospital stay was 41 days (range 28-650). A partial or total pericardiectomy was performed during the HT procedure in 21 patients (42%) due to a severe pericardial reaction. Long-term survival rates after an HT at 5, 10 and 12 years were 79.1 ± 5.9% (n = 32), 76.5 ± 6.3% (n = 22) and 72.4 ± 7.1% (n = 12), respectively, which was similar to the long-term survival for a primary HT without TAH-t during the same period (n = 686). An HT performed within 3-6 months post-TAH-t implantation appeared to provide the best survival (P = 0.007). Eight (16%) patients required chronic dialysis during the subsequent follow-up period, with 3 patients requiring a kidney transplant.

CONCLUSIONS

The long-term outcomes with the SynCardia TAH-t as a bridge to transplant in patients with severe biventricular failure are very encouraging. Our review noted that an HT following TAH-t can be technically challenging, especially in the case of a severe pericardial reaction, with potential pitfalls that should be recognized preoperatively.

Total artificial heart implantation after right ventricular intimal spindle cell sarcoma

This paper describes the case of a patient with a high-grade spindle sarcoma in the right ventricle. The patient underwent total cardiectomy followed by the implantation of a total artificial heart. The patient had an uneventful postoperative course and remained tumour-free for 12 months; after that time period she underwent a heart transplant.

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.

Cardiac tumors invading the right ventricle; Aggressive Surgical Management with backup mechanical circulatory support if necessary

BACKGROUND

Primary cardiac tumors are exceedingly rare. Amongst the malignant types, sarcomas are the most frequently encountered. Treatment includes attempted aggressive surgical resection as the only curative option. We report our experience.

METHODS

During the last five years, six patients presented at our institution with complex cardiac tumors with different underlying diagnoses and were at different stages of their disease.

RESULTS

6 patients with median age of 30-years-old underwent surgery in our centre. 3 patients had undergone debulking prior to surgery at our institution. In all patients, the tumor involved the right ventricle. One patient had biventricular involvement, the septum was involved in 4 patients, 2 patients had extracardiac growth, one invading both great vessels, one involving the pericardium and the hilar structures on the right side. Complete resection was achieved in 4 cases, 3 with successful resection-reconstruction, one with cardiectomy and implantation of a total artificial heart. 5 patients are currently alive, 4 free of recurrence.

CONCLUSIONS

Complete radical surgery is the only curative treatment for patients suffering from cardiac tumors. The availability of mechanical circulatory support allows for a more radical surgical approach even including total cardiectomy, possibly resulting in a significant increase in R0 resections.

[Recommendations for emergency management of patients with permanent mechanical circulatory support : Consensus statement of DGTHG, DIVI, DGIIN, DGAI, DGINA, DGfK and DGK]

The prevalence of patients living with long-term mechanical circulatory support (MCS) is rapidly increasing due to improved technology, improved survival, reduced adverse event profiles, greater reliability and mechanical durability, and limited numbers of organs available for donation. Patients with long-term MCS are very likely to require emergency medical support due to MCS-associated complications (e.g., right heart failure, left ventricular assist device malfunction, hemorrhage and pump thrombosis) but also due to non-MCS-associated conditions. Because of the unique characteristics of mechanical support, management of these patients is complicated and there is very little literature on emergency care for these patients. The purpose of this national scientific statement is to present consensus-based recommendations for the initial evaluation and resuscitation of adult patients with long-term MCS.

The total artificial heart in pediatrics: outcomes in an evolving field

Background

The use of the SynCardia temporary total artificial heart (TAH-t) in adults has increased with time. The development of the smaller, 50 cc TAH-t has expanded the potential applications of the device in children. We sought to describe the evolving use of the TAH-t over time and describe outcomes in the current era.

Methods

The SynCardia database was queried to identify all pediatric patients ≤18 years of age implanted with the device between December 1985 and October 2019. Patient demographics, clinical outcome and support characteristics collected.

Results

Fifty-one children were supported, 36 with the 70 cc TAH-t and 15 with the 50 cc TAH-t with a total support time of 6,243 days. The number of implants has increased with time (19 between 2015 and 2019). A total of 13 patients have been converted to Freedom Driver support, seven 50 cc TAH-t and six 70 cc TAH-t. The majority of implants in the last 5 years (15/19, 79%) have been with the 50 cc TAH-t. The most common diagnosis was dilated cardiomyopathy [24 (47%)] and the average age at the time of implant was 16±2 years old. Overall survival for the patient cohort was 71%.

Conclusions

The use of the SynCardia TAH-t to support children with end-stage heart failure has increased over time. Clinical outcomes with both the 50 cc and 70 cc TAH-t are similar to reported outcomes in adults who require TAH-t or other methods of biventricular support.

Hemocompatibility and safety of the Carmat Total Artifical Heart hybrid membrane

The Carmat bioprosthetic total artificial heart (C-TAH) is a biventricular pump developed to minimize drawbacks of current mechanical assist devices and improve quality of life during support. This study aims to evaluate the safety of the hybrid membrane, which plays a pivotal role in this artificial heart. We investigated in particular its blood-contacting surface layer of bovine pericardial tissue, in terms of mechanical aging, risks of calcification, and impact of the hemodynamics shear stress inside the ventricles on blood components. Hybrid membranes were aged in a custom-designed endurance bench. Mechanical, physical and chemical properties were not significantly modified from 9 months up to 4 years of aging using a simulating process. Exploration of erosion areas did not show no risk of oil diffusion through the membrane. Blood contacting materials in the ventricular cavities were subcutaneously implanted in Wistar rats for 30 days as a model for calcification and demonstrated that the in-house anti-calcification pretreatment with Formaldehyde-Ethanol-Tween 80 was able to significantly reduce the calcium concentration from 132 μg/mg to 4.42 μg/mg (p < 0.001). Hemodynamic simulations with a computational model were used to reproduce shear stress in left and right ventricles and no significant stress was able to trigger hemolysis, platelet activation nor degradation of the von Willebrand factor multimers. Moreover, explanted hybrid membranes from patients included in the feasibility clinical study were analyzed confirming preclinical results with the absence of significant membrane calcification. At last, blood plasma bank analysis from the four patients implanted with C-TAH during the feasibility study showed no residual glutaraldehyde increase in plasma and confirmed hemodynamic simulation-based results with the absence of hemolysis and platelet activation associated with normal levels of plasma free hemoglobin and platelet microparticles after C-TAH implantation. These results on mechanical aging, calcification model and hemodynamic simulations predicted the safety of the hybrid membrane used in the C-TAH, and were confirmed in the feasibility study.

Surgical Approaches in Heart Failure

Heart failure is a progressive condition that continues to increase in both incidence and prevalence despite pharmacologic treatment. The high rate of morbidity and mortality associated with advanced heart failure has led to exploration of additional treatments, which include surgical interventions to improve outcomes. Heart transplant remains the gold standard but, because of the persistent donor shortage and increasing number of patients with advanced heart failure, mechanical circulatory support is gaining acceptance and can be used as a bridge to heart transplant for those eligible or as destination therapy.

Trends in utilization, mortality, major complications, and cost after total artificial heart implantation in the United States (2009-2015)

OBJECTIVE

Total artificial heart (TAH) is a viable bridge to transplant (BTT) strategy for patients with severe biventricular failure or complex congenital heart disease. These patients have higher mortality and morbidity than patients undergoing left ventricular assist device (LVAD) implantation. To assess national trends in in-hospital mortality, major complications, cost, length of stay, and disposition of patients undergoing TAH implantation.

METHODS

Data from the National Inpatient Sample, the largest all-payer inpatient data set in the United States, and the US Census Bureau, for the years 2009 to 2015 were analyzed. Participants included all adult patients who received TAH from 2009 to 2015. Endpoints included in-hospital mortality, in-hospital complications, heart transplantation (HT) in the same admission, length of stay, cost, and disposition at the time of discharge.

RESULTS

We identified a total of 143 (weighted = 703) TAH implantations. The number of TAH implants increased during the study period (average annual change +5.8%, p = 0.03). Rates of in-hospital mortality and major complications including ischemic stroke, major bleeding, postoperative infections, acute kidney injury requiring dialysis, and HT did not change significantly over the study period. Although the length of stay and disposition patterns did not change over time, we found a significant increase in cost of hospitalization (average annual change +44,362, p = 0.01). The number of HT during the same hospital stay decreased significantly (average annual change -8.1%, p = 0.02).

CONCLUSION

In-hospital mortality and complication rates associated with TAH implantation remain increased and did not change in the era of continuous flow LVADs.

The Evolution of Mechanical Circulatory Support

The field of mechanical circulatory support (MCS) has evolved from earlier-generation pulsatile-flow devices that were primarily used to support critically ill patients in the hospital to newer-generation continuous-flow devices that permit hospital discharge and resumption of normal life activities. The technology is used to bridge transplant-eligible patients and can be used for long-term support of patients who are transplant ineligible. Left ventricular assist devices are proved to improve long-term survival and quality of life for patients with advanced heart failure. Adverse events associated with MCS therapy remain the Achilles heel of the field and strategies to improve biocompatibility are ongoing.

Death, Devices, and Double Effect

Along with the growing utilization of the total artificial heart (TAH) comes a new set of ethical issues that have, surprisingly, received little attention in the literature: (1) How does one apply the criteria of irreversible cessation of circulatory function (a core concept in the Uniformed Determination of Death Act) given that a TAH rarely stops functioning on its own? (2) Can one appeal to the doctrine of double effect as an ethical rationale for turning off a TAH given that this action directly results in death? And, (3) On what ethical grounds can a physician turn off a TAH in view of the fact that either the intent of such an action or the outcome is always, and necessarily, death? The aim of this article is not to answer these questions but to highlight why these questions must be explored in some depth given the growing use of TAH technology.

Total artificial heart implantation in a young Marfan syndrome patient

INTRODUCTION

Cardiovascular complications represent the leading cause of morbidity and mortality in patients with Marfan syndrome. Here, we describe a unique case where a total artificial heart was implanted in a young Marfan syndrome woman.

METHODS

A 22-year-old postpartum African American female with Marfan syndrome developed multiple severe valve dysfunction and biventricular failure that was refractory to medical management. She previously had a Bentall procedure for Type A aortic dissection and repair of a Type B dissection.

RESULTS

We implanted a total artificial heart with a good outcome.

CONCLUSION

Total artificial heart is a durable option for severe biventricular failure and multiple valvular dysfunction as a bridge to transplant in a young patient with Marfan syndrome.

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

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

A Physical Heart Failure Simulation System Utilizing the Total Artificial Heart and Modified Donovan Mock Circulation

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.

Thrombotic Depositions on Right Impeller of Double-Ended Centrifugal Total Artificial Heart In Vivo

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.

Deairing Techniques for Double-Ended Centrifugal Total Artificial Heart Implantation

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.

Mechanical circulatory assist devices: a primer for critical care and emergency physicians

Mechanical circulatory assist devices are now commonly used in the treatment of severe heart failure as bridges to cardiac transplant, as destination therapy for patients who are not transplant candidates, and as bridges to recovery and “decision-making”. These devices, which can be used to support the left or right ventricles or both, restore circulation to the tissues, thereby improving organ function. Left ventricular assist devices (LVADs) are the most common support devices. To care for patients with these devices, health care providers in emergency departments (EDs) and intensive care units (ICUs) need to understand the physiology of the devices, the vocabulary of mechanical support, the types of complications patients may have, diagnostic techniques, and decision-making regarding treatment. Patients with LVADs who come to the ED or are admitted to the ICU usually have nonspecific clinical symptoms, most commonly shortness of breath, hypotension, anemia, chest pain, syncope, hemoptysis, gastrointestinal bleeding, jaundice, fever, oliguria and hematuria, altered mental status, headache, seizure, and back pain. Other patients are seen for cardiac arrest, psychiatric issues, sequelae of noncardiac surgery, and trauma. Although most patients have LVADs, some may have biventricular support devices or total artificial hearts. Involving a team of cardiac surgeons, perfusion experts, and heart-failure physicians, as well as ED and ICU physicians and nurses, is critical for managing treatment for these patients and for successful outcomes. This review is designed for critical care providers who may be the first to see these patients in the ED or ICU.

Cardiopulmonary exercise testing responses to different external portable drivers in a patient with a CardioWest Total Artificial Heart

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.

Potential alternative approaches to xenotransplantation

There is an increasing worldwide shortage of organs and cells for transplantation in patients with end-stage organ failure or cellular dysfunction. This shortage could be resolved by the transplantation of organs or cells from pigs into humans. What competing approaches might provide support for the patient with end-stage organ or cell failure? Four main approaches are receiving increasing attention - (i) implantable mechanical devices, although these are currently limited almost entirely to devices aimed at supporting or replacing the heart, (ii) stem cell technology, at present directed mainly to replace absent or failing cells, but which is also fundamental to progress in (iii) tissue engineering and regenerative medicine, in which the ultimate aim is to replace an entire organ. A final novel potential approach is (iv) blastocyst complementation. These potential alternative approaches are briefly reviewed, and comments added on their current status and whether they are now (or will soon become) realistic alternative therapies to xenotransplantation.

Hemodynamics of a functional centrifugal-flow total artificial heart with functional atrial contraction in goats

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.

A hybrid mock circulation loop for a total artificial heart

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.

Modeling of a rotary blood pump

The accurate representation of rotary blood pumps in a numerical environment is important for meaningful investigation of pump-cardiovascular system interactions. Although numerous models for ventricular assist devices (VADs) have been developed, modeling methods for rotary total artificial hearts (rTAHs) are still required. Therefore, an rTAH prototype was characterized in a steady flow, hydraulic test bench over a wide operational range for pump and hydraulic parameters. In order to develop a generic modeling method, a data-driven modeling approach was chosen. k-Nearest-neighbors, artificial neural networks, and support vector machines (SVMs) were the machine learning approaches evaluated. The best performing parameters for each algorithm were determined via optimization. The resulting multiple-input-multiple-output models were subsequently assessed under identical conditions, and a SVM with a radial basis function kernel was identified as the best performing. The achieved root mean squared errors were 0.03 L/min, 0.06 L/min, and 0.18 W for left and right flow and motor power consumption, respectively. In comparison with existing models for VADs, the flow errors are more than 70% lower. Further advantages of the SVM model are the robustness to measurement noise and the capability to operate outside of the trained parameter range. This proposed modeling method will accelerate further device refinements by providing a more appropriate numerical environment in which to evaluate the pump-cardiovascular system interaction.

The challenge of home discharge with a total artificial heart: the La Pitie Salpetriere experience

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Anatomic fitting of total artificial hearts for in vivo evaluation

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.