In an attempt to determine whether mural thrombus in a dilated left ventricle is associated with specific flow patterns, a study was undertaken to assess qualitatively and quantitatively the flow characteristics by conventional pulsed and two-dimensional Doppler color flow examination. Forty patients with cardiomyopathy formed the study group (20 with an apical thrombus and 20 without). The groups did not differ with respect to age, gender, origin of ventricular dysfunction, ventricular size and ejection fraction. Guided by the Doppler color flow pattern, a quantitative analysis of flow velocity profile in the ventricular inflow and outflow "compartments" was performed by serial pulsed wave Doppler sampling. Inflow velocity at the ventricular apex was significantly lower in the thrombus group than in the no thrombus group (11.7 +/- 15.3 versus 28.3 +/- 10.5 cm/s, p less than 0.0001). Flow velocities were generally lower in the thrombus group at the other levels in the inflow compartment (that is, mitral anulus, leaflet tips and papillary muscle level). The systolic flow velocity at the apex was similarly significantly lower in the thrombus group than in the no thrombus group (7.1 +/- 8.1 versus 15.3 +/- 7.0 cm/s, p less than 0.001). Additionally, a higher prevalence of mitral regurgitation was noted in the no thrombus group (14 patients) than in the thrombus group (3 patients). Thus, specific abnormal flow profiles are associated with a left ventricular thrombus. Whether the abnormal flow is a primary event in the genesis of left ventricular thrombus or occurs secondary to development of the thrombus cannot be determined from this study.