4D flow MRI enhances prototype testing of a total artificial heart

The shortage of donor hearts urges the need for total artificial hearts (TAHs). Existing TAHs cause complications like infection, stroke, and hemolysis due to adverse flow dynamics, but assessment of flow in a TAH is challenging. We investigated the feasibility of using 4D flow magnetic resonance imaging (MRI) to assess blood flow dynamics in the left side of a pulsatile TAH under representative physiological conditions. A prototype of a pulsatile TAH was modified using powder bed fusion and fused filament fabrication 3D printing techniques to function in an MRI environment. The TAH connected to an MRI compatible mock circulatory loop allowed variable physiological conditions (i.e. heart rate 80, 105, 120 bpm) and was scanned with two different velocity encodings. Flow patterns and turbulent kinetic energy were measured with high accuracy in a short measurement time and analyzed. Stasis and viscous energy loss in the artificial heart were found to be similar to healthy native hearts. Elevated turbulent kinetic energy was found in several areas, but values were well below those found in patients with valvular disease. Using 4D flow MRI in combination with 3D printing can facilitate assessment of flow dynamics in TAHs and enable a rapid iterative design process.