In Vivo Measurements of Blood Transport Patterns and Stasis in the Human Left Ventricle

Because the left ventricle (LV) is not completely emptied during systole, oxygenated blood from the left atrium interacts with residual blood from preceding cycles. It is hypothesized that LV flow is optimal for transporting blood under normal conditions; yet proving this remains a challenge. Furthermore, clinical evaluation of LV hemodynamics has tremendous diagnostic importance for patients with cardiomyopathy. We have performed Doppler-echocardiography on 6 patients with dilated cardiomyopathy and 6 healthy volunteers. Using novel processing of the color-Doppler data, bi-directional velocity field maps in the apical long axis plane were derived. Resulting flow data was used to perform Lagrangian coherent structure (LCS) computation, which enabled novel characterization of the transport topology in the LV during filling and ejection. This framework was used to quantify stasis in the LV, which can be used as a surrogate for diagnosing pumping deficiencies and thrombosis risk. This framework also enables characterization of LV vortices, which have previously received much attention using Eulerian characterizations. The framework presented here uncovers the well-defined boundaries to both E-wave and A-wave filling vortices, which has not been previously reported.