PakFVAD: Totally Implantable Integrated Aortic-Turbine Venous-Assist Device for Fontan Patients

Votes: 2
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Medical

Worldwide over 1 million children are born every year with congenital heart diseases such as hypoplastic left heart syndrome. A special heterogeneous subset of this group encompasses babies born with malformations of their heart chambers and connecting vessels that have only one functional ventricle. The incidence of patients born with functional univentricular physiology is approximately 2 per every 1000 births. Without surgical intervention, this combination of cardiac anomalies is fatal within the first 2 weeks of life. For these patients, the current treatment paradigm consists of three staged, open heart surgeries, which culminate in the Fontan (single-ventricle) physiology. As the patient ages, this paradoxical circulation gradually fails, because of its high venous pressure levels. Reversal of the Fontan paradox requires extra subpulmonic energy that can be provided through mechanical assist devices. All previously designed and available Fontan Assist Devices (FVADs) are externally powered and very expensive. PakFVAD is a totally implantable integrated aortic-turbine venous-assist device, which does not need an external drive power and maintains low venous pressure chronically, for the Fontan circulation.

Computational fluid dynamics (CFD) is a powerful tool to virtually characterize different designs of turbomachinery of all types including turbines and pumps, especially during the preliminary design phase. Design and analysis of a blood turbine coupled with a centrifugal pump, acting as a venous assist device are done to find the optimal design with reduced hemolysis and other related risks. Computational fluid dynamics analysis is performed on different initial designs. A stress-based CFD code is also implemented to estimate the quantitative hemolysis. The best designs with an aortic steal in a safe range and optimum performance are then selected and tested for hydraulic performance. The prototypes of the device operate at 800-1250 revolutions per minute and extract up to 15-25% systemic blood from the aorta to use this hydrodynamic energy to drive a blood turbine, which in turn drives a mixed-flow venous pump. The turbine is magnetically coupled with the pump to keep the oxygen-rich and deoxygenated blood from mixing. By transferring part of the available energy from the single-ventricle outlet to the venous side, the PakFVAD system is able to generate up to approximately 5 mmHg venous recovery while supplying the entire caval flow.

The study, in a nutshell, showed that a totally implantable integrated aortic-turbine venous-assist system is feasible, which will eliminate the need for external power for Fontan mechanical venous assist and combat gradual postoperative venous remodeling and Fontan failure. The numerical design, as well as the experimentation of the initial prototypes, have been completed. Now, different pivoting styles and impeller designs with minor iterations are under experimentation. Moreover, efforts are being made to develop a complete mock circulatory loop and carry out the in vitro testing of the devices as well as the experimental evaluation of hemodynamic performance. This initial design and development study will pave the way for future research and eventually a locally designed and manufactured totally implantable integrated aortic-turbine venous-assist system that will save many precious lives.

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  • ABOUT THE ENTRANT

  • Name:
    Muhammad Ahmad Raza
  • Type of entry:
    individual
  • Profession:
    Student
  • Muhammad Ahmad is inspired by:
    Historically, natural and biological sciences have been progressing forward independently for many centuries. However, rapid scientific advancement that took place in the last two centuries has rendered these fields dependent on each other. Now any kind of advancement in one field can significantly contribute to the ongoing research in other fields. The revolution in the field of computation is the best example of this phenomenon. Nowadays, computers, mathematical models, and engineering fields such as mechanical engineering are playing an important role in the health care sector. While the developed world is coming up with innovative solutions against health issues every day, these fields are mostly ignored in developing countries like Pakistan. More than 1 million babies are born, annually worldwide, with congenital heart diseases like hypoplastic left heart syndrome. Whereas in Pakistan alone, more than 60,000 children are born with congenital heart anomalies, yearly. As per WHO data of 2016 in Pakistan, around 250,000 (19% of total deaths) annual deaths were due to heart diseases but in just three years, these deaths increased to 406,870 (29% of total deaths) in 2018. This dangerous increase in the death rate due to CHD demands us to take serious measures to improve the health condition of heart patients. The design and development of PakFVAD is the first study of its kind in Pakistan, where no previous work has been done on the development of mechanical circulatory support to cater congenital heart diseases. The purpose behind this study is to pave the way for local designing and manufacturing of advanced, durable, and affordable cardiovascular assist devices.
  • Software used for this entry:
    ANSYS, MATLAB, LabVIEW, COMSOL, PTC Creo, SpaceClaim, SolidWorks
  • Patent status:
    none