Accurate volume determination in the isolated ejecting canine left ventricle by two-dimensional echocardiography

Two-dimensional echocardiography can provide serial cross-sectional images of the left ventricular cavity. We examined whether such serial images from steady-state ejecting hearts would allow three-dimensional reconstruction and accurate volume estimation without major geometric assumptions. Cross-circulated, paced dog hearts were suspended in a blood-filled tank. Serial cross-sectional images were taken at 3-mm intervals along the vertical axis. Left ventricular cavity and muscle areas of each image were planimetered with a light-pen system and summated for volume: total volume = sigma (areas x 3 mm). Direct left ventricular volume was measured through the cardiac cycle with a volumetric chamber connected to a balloon in the ejecting left ventricle. In six hearts, 67 separate direct volume measurements (range 9.5--54.7 ml) from various points in the cardiac cycle were compared with the simultaneous echo volume measurements. By least squares linear regression, echo volume = 1.01 (direct volume) - 0.44 ml; r = 0.972, SEE = 2.93 ml. Provided accurate cross-sectional localization is available, these studies suggest that extremely accurate steady-state left ventricular volume can be determined noninvasively in the ejecting heart from multiple cross-sectional images.