Real-time, three-dimensional echocardiography: Feasibility of dynamic right ventricular volume measurement with saline contrast

Background:The asymmetry and complex shape of the right ventricle have made:it difficult to determine right ventricular (RV) volume with 2-dimensional echocardiography. Three-dimensional cardiac imaging improves visualization of cardiac anatomy but is also complex and time consuming. A newly developed volumetric scanning system holds promise of obviating past limitations. Methods Real-time, transthoracic 3-dimensional echocardiographic images of the right ventricle were obtained with a high-speed volumetric ultrasound system that uses a 16:1 parallel processing schema From a 2.5 MHz matrix phased-array scanner to interrogate an entire pyramidal volume in real time. The instrumentation was used to measure RV volume in 8 excised canine hearts; dynamic real-time 3-dimensional images were also obtained from 14 normal subjects. Results Three-dimensional images were obtained in vitro and in vivo during intravenous hand-agitated saline injection to determine RV volumes. The RV volumes by real-time 3-dimentional echocardiography are well correlated with those of drained in vitro (y = 1.26x -9.92, r = 0.97; P < .0001, standard error of the estimate = .3.26 mL). For human subjects, the end-diastolic and end-systolic RV volumes were calculated by tracing serial cross-sectional, inclined C scans; functional data were validated by comparing the scans with conventional 2-dimensional echocardiographic indexes of left ventricular stroke volume. Conclusions These data indicate that RV volume measurements of excised heart by real-time 3-dimensional echocardiography are accurate and that beat-to-beat RV quantitative measurement applying this imaging method is possible. The new application of real-time 3-dimensional echocardiography presents the opportunity to develop new descriptors of cardiac performance.