ESOT 2013 Report – Growing organs and growing old in transplantation: Artificial organs

Heinrich Schima, Vienna, Austria – In the last decades, ventricular-assist devices (VADs) – artificial hearts – have gone from pioneering experiments to offering a real alternative to heart transplantation for a large proportion of patients on the waiting list. With the latest pumps and in the hands of the most experienced surgeons, the long-term survival rates on a VAD closely resembles those after a heart transplantation. Professor Heinrich Schima from the Medical University of Vienna summarised the current status of VADs versus heart transplantation and described some of the many challenges ahead in this field.

 

Although the very first blood pump for clinical use was described by James Blundell as far back as 1824, it took until 1966 before a VAD was used successfully in a human being for the first time [1], and the first chronic total artificial heart was not fitted until 1982 [2]. In these early pioneering days, VADs were developed largely in competition with heart transplantation. By the mid-1980s, however, clinicians had become to increasingly regard VADs as a bridge to heart transplantation [3-5]. Some of the patients included in this early programme survived for up to 20 years after their heart transplantation.

 

The first successful VADs employed pulsatile pumps; from the late 1980s onwards, the first rotary-pump VADs were developed and today this is the principal type of pump used in adult patients, with dramatically improved survival as a result. In 2001, a team at the Texas Heart Institute reported significantly improved survival rates with a pulsatile-pump VAD compared with medical treatment alone [6]. More recent reports suggest that patients fitted with rotary-pump devices are more than twice as likely to be alive after two years than patients fitted with pulsatile-pump VADs [7,8]. A large multi-centre study in the US reported survival rates at two years of 58% with a rotary-pump device versus 24% with a pulsatile-pump device (p=0.008) [7]. Not surprisingly, more experienced centres tend to achieve higher survival rates, highlighting the importance for centres to retain experienced medical, surgical and auxiliary staff to maintain clinical outcomes [7].

 

Despite the rapid technical and clinical development and the success of modern VADs, a number of challenges remain to be overcome. The most important of these, according to Professor Schima, is to optimise the biocompatibility of VADs to minimise, or ideally eliminate, the need for anticoagulation. Other issues include the use of increasingly smaller pumps which will require minimally invasive implantation techniques, and, further ahead, the development of wireless energy transfer techniques to eliminate the need for transcutaneous power cables.

 

As the use of VADs looks set to become more widespread, with increased survival rates and wider indications especially in older patients, social issues are likely to arise around the psychological impact of VAD therapy on patients and their families, acceptance of VADs eg in workplaces, and how to manage VAD patients in palliative care. In addition, the financial cost will be considerable.

 

VADs have become an established part of routine medical practice – nevertheless, for Professor Schima, the field of artificial hearts remains an exciting adventure and he feels privileged to have made his contribution.

 

References

1.  De Bakey, M.E., D. Liotta, and C.W. Hall, Prospects for and implications of the artificial heart. J Rehabil, 1966. 32(2): p. 106-7.

2.  DeVries, W.C. and L.D. Joyce, The artificial heart. Clin Symp, 1983. 35(6): p. 1-32.

3.  Portner, P.M., et al., Implantable electrical left ventricular assist system: bridge to transplantation and the future. Ann Thorac Surg, 1989. 47(1): p. 142-50.

4.  Trubel, W., et al., Total artificial heart bridging: a temporary support for deteriorating heart transplantation-candidates–methods and results. Thorac Cardiovasc Surg, 1987. 35(5): p. 277-82.

5.  Hetzer, R., et al., Heart transplantation in Berlin. Clin Transpl, 1989: p. 89-92.

6.  Frazier, O.H., et al., Multicenter clinical evaluation of the HeartMate vented electric left ventricular assist system in patients awaiting heart transplantation. J Thorac Cardiovasc Surg, 2001. 122(6): p. 1186-95.

7.  Slaughter, M.S., et al., Advanced heart failure treated with continuous-flow left ventricular assist device. N Engl J Med, 2009. 361(23): p. 2241-51.

8.  Pagani, F.D., et al., Extended mechanical circulatory support with a continuous-flow rotary left ventricular assist device. J Am Coll Cardiol, 2009. 54(4): p. 312-21.