REAL-TIME 3-DIMENSIONAL ECHOCARDIOGRAPHY FOR DETERMINING RIGHT-VENTRICULAR STROKE VOLUME IN AN ANIMAL-MODEL OF CHRONIC RIGHT-VENTRICULAR VOLUME OVERLOAD

Background-The lack of a suitable noninvasive method for assessing rig ht ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our animal study wa s to test a new real-time three-dimensional (3D) echo imaging system f or evaluating RV stroke volumes.Methods and Results-Three to 6 months before hemodynamic and 3D ultrasonic study, the pulmonary valve was ex cised from 6 sheep (31 to 59 kg) to induce RV volume overload. At the subsequent session, a total of 14 different steady-state hemodynamic c onditions were studied, Electromagnetic (EM) flow probes were used for obtaining aortic and pulmonic flows. A unique phased-array volumetric 3D imaging system developed at the Duke University Center for Emergin g Cardiovascular Technology was used for ultrasonic imaging. Real-time volumetric images of the RV were digitally stored, and RV stroke volu mes were determined by use of parallel slices of the 3D RV data set an d subtraction of end-systolic cavity volumes from end-diastolic cavity volumes. Multiple regression analyses showed a good correlation and a greement between the EM-obtained RV stroke volumes (range, 16 to 42 mL /beat) and those obtained by the new real-time 3D method (r=0.80; mean difference, -2.7+/-6.4 mL/beat). Conclusions-The real-time 3D system provided good estimation of strictly quantified reference RV stroke vo lumes, suggesting an important application of this new 3D method.