Mechanical circulatory support increased left atrial washout by 50% under rigid-wall conditions and 27% with wall contraction, but cannula advancement increased shear stress by up to 151%.
How does mechanical circulatory support with left atrial inflow cannulation affect left atrial blood flow dynamics and thrombosis risk in a HFpEF model?
In a HFpEF model, mechanical circulatory support with LA cannulation enhances LA flow washout, but lower insertion depth and reduced pump flow may be needed to mitigate cannula-related thrombus risk.
Mechanical circulatory support (MCS) alters cardiac flow dynamics and can contribute to thrombosis. Although commonly used for heart failure with reduced ejection fraction, its application in patients with preserved ejection fraction (HFpEF), nearly half of all heart failure cases, remains limited. Left atrial (LA) inflow cannulation may be advantageous for HFpEF patients due to their reduced ventricular volume, but the resulting LA flow disturbances are not well understood. This study evaluates how MCS affects LA blood flow dynamics in a HFpEF patient to clarify mechanisms influencing thrombosis risk. The effects of cannula length and drainage flow rate on thrombosis-related flow characteristics were quantified. To assess the importance of atrial mechanics, simulations incorporating LA contraction were compared with rigid-wall models, addressing the common simplification of rigid geometries. Predictions were validated against two-dimensional magnetic resonance imaging measurements obtained using a soft-robotic LA model. MCS increased washout by 50% under rigid-wall conditions and 27% with wall contraction compared with unassisted flow. However, thrombus risk increased with cannula advancement, driven by up to 151% higher shear stress. LA wall contraction reduced stasis by 68% and improved washout but also elevated predicted wall shear stress. Cannula advancement and its proximity to pulmonary veins and the mitral valve altered local flow structures and shear stress distributions, demonstrating the benefit of patient-specific positioning. Overall, MCS can enhance LA flow, but lower insertion depth and reduced pump flow may mitigate cannula-related thrombus risk. Even minimal atrial contraction notably affected washout, residence time, and shear stress patterns, highlighting its importance in thrombosis assessment.
Langer et al. (Mon,) conducted a other in Heart failure with preserved ejection fraction (HFpEF) (n=1). Mechanical circulatory support (MCS) vs. Unassisted flow was evaluated on Left atrial blood flow dynamics (washout, shear stress, stasis). Mechanical circulatory support increased left atrial washout by 50% under rigid-wall conditions and 27% with wall contraction, but cannula advancement increased shear stress by up to 151%.