Future Prospects for the Total Artificial Heart

SUMMARY

A total artificial heart (TAH) is the sole remaining option for patients with biventricular failure who cannot be rescued by left ventricular assist devices (LVADs) alone. However, the pulsatile TAH in clinical use today has limitations: large pump size, unknown durability, required complex anticoagulation regimen, and association with significant postsurgical complications. That pump is noisy; its large pneumatic driving lines traverse the body, with bulky external components for its drivers. Continuous-flow pumps, which caused a paradigm shift in the LVAD field, have already contributed to the rapidly evolving development of TAHs. Novel continuous-flow TAHs are only in preclinical testing or developmental stages. We here review the current state of TAHs, with recommended requirements for the TAH of the future.

KEYWORDS:

• Artificial heart
• Heart failure
• Ventricular assist device
• Heart transplantation
• Pulsatile flow
• Continuous flow

Financial & competing interests disclosure

The work on Cleveland Clinic continuous-flow total artificial heart was supported with federal funding obtained from the National Heart, Lung and Blood Institute, National Institutes of Health, under grant 5R01HL096619 received by F. Fukamachi. D. Horvath is an inventor of the Cleveland Clinic continuous-flow total artificial heart. The technology was licensed to Cleveland Heart, Inc., a Cleveland Clinic spin-off company. If this total artificial heart is successful, the inventors and Cleveland Clinic may benefit. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• The total artificial heart (TAH) is the sole remaining option for end-stage heart failure patients who await donor heart transplantation, given the shortage of donor hearts and the conditions of patients who cannot be helped by left ventricular assist devices (LVADs) alone.

• The only current options are the SynCardia TAH, CARMAT TAH, and dual continuous-flow (CF) TAH. Among mechanical circulatory assist devices, the SynCardia demonstrated the best results as a bridge to transplant, but otherwise the dearth of clinical data makes comprehensive assessments difficult.

• The paradigm shift from pulsatile flow to CF in LVADs, which improved clinical outcomes, has had the largest impact on the TAH field. The only single-piece CFTAHs in development are Cleveland Clinic’s CFTAH and the Texas Heart Institute’s BiVACOR, which are still in preclinical studies.

• The CF design has the advantages of reduced pump size and improved durability. On the other hand, one must keep in mind all possible persistent complications, including gastrointestinal bleeding, acquired von Willebrand syndrome, and impaired platelet aggregation, which have been reported to arise after CFVAD use.

• Larger epidemiologic surveys should be undertaken to assess the real costs of use of a TAH; these data are currently lacking. Depending on system costs, a TAH may be similar in expense to clinically used biventricular devices; however, the cost of medication may be reduced.

• Proper patient selection is critical to achieve success with any device, and a given device should be tailored to individual patient needs. The TAH of the future should provide improved durability, increased survival benefit, and lower rates of adverse events.