We used simultaneous echocardiography, phonocardiography, and high-fidelity micromanometry to investigate the impact of the movement of a large pedunculated left atrial myxoma on hemodynamics. The case we have described shows that (1) the early diastolic sound (tumor plop) coincided with maximal excursion of the tumor in the left ventricular inflow tract, (2) tumor movements during mid to late diastole corresponded to low-frequency oscillations in left ventricular pressure, (3) tumor expulsion from the left ventricle into the left atrium was initiated during "isovolumic" contraction but continued into the early ejection phase, (4) mitral valve closure was abnormally delayed until after the onset of aortic ejection, and (5) systolic ejection was initiated before coaptation of the mitral valve leaflets. These findings support the theory that tumor motion contributes to both systolic and diastolic vibrations of the entire cardiohemic system.