OBJECTIVE: Limited data are available on prosthetic heart valve performance at reduced and increased cardiac output (CO) as most studies were carried at 5L/min. This study aims to close this gap by investigating blood flow patterns in aortic mechanical (MHV) and biological (BHV) heart valves at low, normal and elevated CO using Tomographic Particle Image Velocimetry (Tomo-PIV).
METHODS: Two MHVs (TRIFLO, Novostia; On-X, CryoLife) and a BHV (PERIMOUNT, Edwards Lifesciences) of 21mm were mounted in a pulse duplicator. The three-dimensional flow field was measured with a multi-view imaging system (Tomo-PIV). The flow rate was set at 3, 5 and 7L/min with aortic pressure of 60/40, 120/80 and 170/105mmHg for low, normal and elevated CO, respectively.
RESULTS: Three valves had similar flow rates but varied in systolic retrograde flow. The tri-leaflet valves showed similar flow topology characterized by a central systolic jet, with three side jets in the sinuses for the TRIFLO. The BMHV featured two semi-circular jets near the aortic wall and a smaller central jet. The TRIFLO showed lower planar turbulent kinetic energy (TKE) while it was comparable for the BMHV and the BHV. However, peak values were identified closer to the sinuses for the BMHV.
CONCLUSIONS: Increasing CO led to higher turbulent kinetic energy and a spatially extended influence of the valve on the flow in the ascending aorta. In all configurations, the BMHV shows higher turbulent production and dissipation rate than other valves. The higher TKE levels near the sinuses associate with higher retrograde flow suggest that the blood flowing back into the sinuses experiences a higher stress level. Lower peak values of TKE and velocity, together with a flow topology similar to the BHV, indicated that blood is exposed to lower level of stress for the TRIFLO.
