Accuracy of real-time three-dimensional echocardiography for quantifying right ventricular volume: static and pulsatile flow studies in an anatomic in vitro model.

Abstract

The complex structural geometry of the right ventricle hinders accurate assessment of right ventricular volume and function on conventional two-dimensional echocardiography. We sought to evaluate the accuracy of real-time three-dimensional echocardiography for quantifying the volume of the right ventricle in an in vitro experimental study. We developed 39 anatomically accurate latex phantoms of human and porcine right ventricles (range, 24-108 mL) for 39 static and 10 pulsatile models. Real-time three-dimensional scanning was performed with the models placed in a water bath and with a 3.5-MHz probe. In the dynamic models a pulsatile flow pump generated 2 different stroke volumes (29 and 64 mL/beat). Static chamber volumes and stroke volumes were verified by water displacement, which served as a reference standard. Three-dimensional echo right ventricle volumes were determined by tracing derived B- and C-scans, using the Simpson rule. Multiple regression analyses showed an excellent correlation between real-time three-dimensional echocardiographic determinations and the static volumes (B-scan, r = 0.99; C-scan, r = 0.98; P < .001), as well as stroke volumes in the dynamic model (B-scan, r = 0.90; C-scan, r = 0.86; P < .001). However, the C-scans tended to underestimate cavity and stroke volumes more than the B-scans (mean difference for static volume: B-scan, 1.4% +/- 9.8%; C-scan, -7.4% +/- 8.0%; P < .001; mean difference for stroke volumes: B-scan, 3.0% +/- 19.1%; C-scan, -2.5% +/- 20.9%; P < .001). Real-time three-dimensional echocardiography can accurately quantify right ventricle cavity volumes and stroke volumes without geometric assumptions.