Issues in Mechanical Circulatory Support
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Dr Om Prakash Yadava and Professor Gino Gerosa discuss continuous flow devices compared with pulsatile flow devices and the debated issues involved. They also look at futuristic and evolving technologies in mechanical cardiac support and the treatment of end-stage heart failure.
Prof Gerosa strongly votes for continuous flow devices. He feels that this evolution has led to the reduction of the size of the devices, as the valve required to ensure unidirectionality of flow is eliminated from continuous flow devices. This enables their placement within the pericardial space, thereby reducing the chances of infection and consequent morbidity and mortality. He grants that aortic insufficiency and gastrointestinal bleeding are issues with continuous flow devices and that advances in intermittent pulsatility may answer some of these issues. Prof Gerosa believes that continuous flow pumps should be used under all circumstances, be it destination therapy, bridge to recovery, or bridge to transplant. He also discusses other technological advances that he feels will revolutionize mechanical circulatory support (MCS), focusing particularly on advances in cable placement, cable positioning, and transcutaneous energy transfer.
The longest survival with a total artificial heart has been reported at four years with CardioWest’s Syncardia Total Artificial Heart, after which a heart transplant was performed. Prof Gerosa discusses the importance of quality of life for patients living with MCS. When asked how MCS devices compare with heart transplant as destination therapy, Prof Gerosa opines that the survival at two years is equivalent for the two treatment modalities, but beyond that, heart transplant is probably better. He stresses that implantation of a left ventricular assist device should be done early, when the right ventricular function is intact. Despite improved control of risk factors, improved pharmacotherapy, and reduced incidence of left ventricular aneurysms and dyskinetic segments, the absolute number of patients being referred for mechanical circulatory assist and for end-stage heart failure has been increasing.
Looking forward, Prof Gerosa feels that the biological heart and electrically conducting tissues to synchronize the heart will be the disruptive therapies and technologies that evolve in the future. He foresees that cell-based therapies could see more applications down the road. The pig heart, for example, can be decellularized and the scaffold could be seeded with human pluripotent cells. Prof Gerosa predicts that the heart thus recreated would function better, obviating the risk of thrombosis and infection, and would be a fully implantable long-term solution to end-stage heart failure.