3-DIMENSIONAL ECHOCARDIOGRAPHY - IN-VIVO VALIDATION FOR LEFT-VENTRICULAR VOLUME AND FUNCTION

Background. Current two-dimensional quantitative echocardiographic met hods of volume assessment require image acquisition from standardized scanning planes. Left ventricular volume and ejection fraction are the n calculated by assuming ventricular symmetry and geometry. These assu mptions may not be valid in distorted ventricles. Three-dimensional ec hocardiography can quantify left ventricular volume without the limita tions imposed by the assumptions of two-dimensional methods. We have d eveloped a three-dimensional system that automatically integrates two- dimensional echocardiographic images and their positions in real time and calculates left ventricular volume directly from traced endocardia l contours without geometric assumptions. Methods and Results. To stud y the accuracy of this method in quantifying left ventricular volume a nd performance in vivo, a canine model was developed in which instanta neous left ventricular volume can be measured directly with an intraca vitary balloon connected to an external column. Ten dogs were studied at 84 different cavity volumes (4 to 85 cm3) and in conditions of alte red left ventricular shape produced by either coronary occlusion or ri ght ventricular volume overload. To demonstrate clinical feasibility, 19 adult human subjects were then studied by this method for quantific ation of stroke volume. Left ventricular volume, stroke volume, and ej ection fraction calculated by three-dimensional echocardiography corre lated well with directly measured values (r=.98, .96, .96 for volume, stroke volume, and ejection fraction, respectively) and agreed closely with them (mean difference, -0.78 cm3, -0.60 cm3, -0.32%). In humans, there was a good correlation (r=.94, SEE=4.29 cm3) and agreement (mea n difference, -0.98+/-4.2 cm3) between three-dimensional echocardiogra phy and Doppler-derived stroke volumes. Conclusions. Three-dimensional echocardiography allows accurate assessment of left ventricular volum e and systolic function.