Game Changer
A Novel Bioprosthetic Total Artificial Heart Stephan Ensminger, MD, DPhil,1 Michiel Morshuis, MD,1 and Jan Gummert, MD1
H
eart failure continues to be an ever-increasing problem affecting almost 23 million people worldwide.1 It is estimated that 1 in every 5 people will develop heart failure in their lifetime, and the risk is known to increase with age.2 Furthermore, 5% of these patients are so-called endstage patients with terminal heart failure who are refractory to effective medical treatment.3 Heart transplantation remains the treatment of choice for these patients. At the same time, the disparity between available donor hearts and patients in need for cardiac transplantation has grown exponentially throughout recent years.4 Thus, mechanical circulatory support has become an essential alternative for the treatment of end-stage heart failure resulting in an increased use of left ventricular assist devices. Nevertheless, many patients have severe biventricular failure or other conditions such as large recent infarctions, intractable arrhythmias, postinfarction ventricular septal defects, or complex native valve disease, making the implantation of left ventricular assist devices challenging. These patients would benefit from a replacement with a total artificial heart (TAH). The SynCardia TAH (formerly Jarvik 7/CardioWest) device had been approved in Europe and the United States in 1999 and 2004, respectively, as a bridge to heart transplantation.5 To date, more than 1300 patients have received the SynCardia TAH.6 According to a 10-year clinical study by Copeland et al, SynCardia produced a 79% success rate as a bridge to transplantation and reasonable postcardiac transplant outcomes (survival data: 70% at 1 year, 50% at 5 years, and 45% at 8 years).5,7 The mean duration of SynCardia support has been 15 to 90 days at different centers. In an early large series of more than 170 patients in the United States, most patients had been supported by the SynCardia device for less than 2 weeks; the average duration of support had been 24 days, with a total of 37% of patients experiencing severe infectious complications necessitating urgent transplantation.8 However, a recent report had been able to show that 72% of the patients who remained on the device more than 1 year could be successfully transplanted.5 Of note, the mechanical surface requires a strict anticoagulation protocol while the pneumatic driver is linked to significant noise level, all impairing
Received 20 January 2016. 1
Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany. The authors declare no funding or conflicts of interest. Correspondence: Stephan M. Ensminger, MD, DPhil, Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University, Bochum Georgstrasse 11, 32545 Bad Oeynhausen, Germany. (
[email protected]). Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0041-1337/16/10004-699 DOI: 10.1097/TP.0000000000001173
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quality of life.8 Thus, the current use of TAH is significantly limited by adverse effects such as hemorrhagic stroke, thromboembolic events, neurologic complications, and infections.9 The report by Carpentier et al10 describes the very first clinical experience in 2 male patients with the Carmat TAH, a device that uniquely comprises a prosthetic design that is part bovine and part mechanical. The rationale behind the development of the device is that hemocompatible blood chamber surfaces (polytetrafluoroethylene plus treated bovine pericardial tissue) are used to avoid the need for anticoagulation. Physiological pulsatile flow was enabled by Carpentier-Edwards biological heart valves in addition to a viscoelastic contractility providing physiological pressure curves and a right-left side filling algorithm. Furthermore, multiple sensors embedded in the device support an autonomous regulation of pump rate and output in response to activity level, all supported by a single driveline with an 8-mm diameter entering the patient's skin. All those advantages come with the burden of size and weight (1 kg).10 The device has been successfully implanted in 2 patients (76 and 68 years old) as part of a feasibility and safety trial. Both patients recovered rapidly with an almost normalized cardiac output, satisfactory end-organ function, and no signs of neurological dysfunction during an accumulated 344 days of support through the device. Unfortunately, both patients died
Documenting the advantages of hemocompatible surfaces in total artificial hearts is a great step forward.
after 74 and 270 days, respectively, linked to a fatal electronic failure of the device. Of note, no mechanical failure or thrombotic dysfunction was detected until the device failed. Strikingly, in the first patient, the use of hemocompatible materials enabled the withdrawal of all anticoagulants during a 50-day period subsequent to the onset of bleeding complications. Patient #2 required only anticoagulation with acetylsalicylic acid and low–molecular weight heparin after discharge, thus demonstrating the advantages of the hemocompatible blood contact surface. Postmortem histological analysis of the hemocompatible surface membrane demonstrated the absence of thrombotic deposits. Although these advantages are recognized, the absence of a biological backup is inevitably linked to fatal outcomes in case of device malfunction.10 In summary, the verdict on the Carmat TAH as a game changer is still out. With clear advantages on the management of anticoagulation, lack of backup options, technical complexity, size, and weight remain unsolved. Clearly, further research is required to resolve technical challenges with the goal to provide backup options if the device fails. www.transplantjournal.com
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
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Documenting the advantages of hemocompatible surfaces in total artificial hearts is a great step forward. REFERENCES 1. Roger VL. Epidemiology of heart failure. Circ Res. 2013;113:646–659. 2. Bui AL, Horwich TB, Fonarow GC. Epidemiology and risk profile of heart failure. Nat Rev Cardiol. 2011;8:30–41. 3. Costanzo MR, Mills RM, Wynne J. Characteristics of “Stage D” heart failure: insights from the Acute Decompensated Heart Failure National Registry Longitudinal Module (ADHERE LM). Am Heart J. 2008;155: 339–347. 4. Lund LH, Edwards LB, Kucheryavaya AY, et al. The registry of the International Society for Heart and Lung Transplantation: thirty-first official adult heart transplant report—2014; focus theme: retransplantation. J Heart Lung Transplant. 2014;33:996–1008.
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5. Torregrossa G, Morshuis M, Varghese R, et al. Results with SynCardia total artificial heart beyond 1 year. ASAIO J. 2014;60: 626–634. 6. Gerosa G, Scuri S, Iop L, et al. Present and future perspectives on total artificial hearts. Ann Cardiothorac Surg. 2014;3:595–602. 7. Copeland JG, Smith RG, Arabia FA, et al. Cardiac replacement with a total artificial heart as a bridge to transplantation. N Engl J Med. 2004;351: 859–867. 8. Copeland JG, Copeland H, Gustafson M, et al. Experience with more than 100 total artificial heart implants. J Thorac Cardiovasc Surg. 2012;143: 727–734. 9. Patel CB, Cowger JA, Zuckermann A. A contemporary review of mechanical circulatory support. J Heart Lung Transplant. 2014; 33:667–674. 10. Carpentier A, Latremouille C, Cholley B, et al. First clinical use of a bioprosthetic total artificial heart: report of two cases. Lancet. 2015;386: 1556–1563.
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