PIV visualization of flow pattern in left heart ventricle model with double valve replacement

The present study elucidates the flow features evolving within the ventricle of a beating left heart model with two mechanical heart valves (MHVs) fixed in mitral and aortic positions. This configuration represents the clinical case of double valve replacement (DVR). Two types of MHVs were used – bi-leaflet mechanical heart valve (BMHV) and mono-leaflet mechanical heart valve (MMHV). Leaflets of MHVs in the mitral position were aligned to mimic closely that of the anatomical mitral valve, whereas in the aortic position their alignment was varied in two different orientations. A 2D Particle Image Velocimetry (PIV) technique was used to explore flow details in the mid-coronal plane of the left ventricle (LV) for 50 cardiac cycles. The heartbeat was simulated at the rate of 60 cycles per minute maintaining the ejection fraction of 45%. In BMHV cases, both the orientations of the aortic valve (AV) produced entirely different non-physiological flow patterns. But in MMHV cases both the orientations of the aortic valve produced flow patterns similar to the physiological flow patterns. The LV contraction during systole exhibited a strong dependence on the AV orientation. Energy loss (EL) due to viscous dissipation, obtained from the strain rate, shows that phase-wise distribution over a complete cardiac cycle is affected by the AV orientation, but the net integrated values show only a marginal difference for BMHV whereas a significant difference for MMHV. Based on the findings, this study suggests that consideration of the AV orientation is important for better LV performance in the DVR conditions and hence for post-surgical cardiac health.