Assessment of right ventricular volumes and ejection fraction by echocardiography: from geometric approximations to realistic shapes

Abstract

Right ventricular volumes and ejection fraction are challenging to assess by echocardiography, but are well established as functional and prognostic parameters. Three-dimensional (3D) echocardiography has become widespread and relatively easy to use, making calculation of these parameters feasible in the large majority of patients. We review past attempts to estimate right ventricular volumes, current strengths and weaknesses of 3D echocardiography for this task, and compare with corresponding data from magnetic resonance imaging.

Keywords: 3D echocardiography; echocardiography; right ventricle; systolic function; volumes.

Figures

Figure 1

Schematic illustration of the right ventricle and the difficulties to include the whole volume. The inflow and outflow tracts are in the same plane – an oblique sagittal plane – as the apex. The right ventricle (RV) is depicted with the adjacent structures of the right atrium (RA), the pulmonary trunk (PA), the sternum (S), the ascending aorta (Ao), and lung tissue. (A) The sternum, ribs, and lung tissue can shadow the imaging of the RV, in particular the anterior part of the right ventricular outflow tract (RVOT). (B) Either the anterior part of the RV or the apex may not be included in the whole volume when trying to overcome this shadowing, especially if the RV is dilated. Reproduced from Ostenfeld E, Carlsson M, Shahgaldi K, Roijer A & Holm J 2012 Manual correction of semi-automatic three-dimensional echocardiography is needed for right ventricular assessment in adults; validation with cardiac magnetic resonance. Cardiovascular Ultrasound10 1, published as an open access article by Biomed Central.

Figure 2

Examples of fractional area change (FAC) (A and C) in a healthy person (FAC=44%) and (B and D) in a patient with pulmonary arterial hypertension (FAC=13%). A and B are at end-diastole. C and D are at end-systole.

Figure 3

Full-volume three-dimensional datasets cropped to display the cavity of (A) a normal person acquired with the lateral approach and (B) a patient with pulmonary arterial hypertension (PAH) acquired with the medial approach. The right ventricle (RV) and atrium (RA) are enlarged and the septum (*) is bulging into the small left ventricle (LV) in the PAH patient and, at the apex, the right ventricle is larger than the maximum sector angle illustrating the challenge of acquisition of the whole volume.

Figure 4

Example of delineation of a normal right ventricle (RV) in end-diastole showing the endocardial contour detection in green. (A) The three left images (magenta, blue, and green boxes) are the short-axis views at different levels with the left ventricle (LV) to the right of the interventricular septum (*). The upper left image (magenta box) is closer to the base and right ventricular outflow tract (RVOT) and the lower image (green box) closer to the apex. The upper right image (yellow box) is a four-chamber view and the lower right image (purple box) is a right ventricular three-chamber view with tricuspid valve (TV), apex, and pulmonary valve (PV) in the same projection. The dashed colored lines represent the plane of the boxes with the corresponding color. (B) Example of a three-dimensional echocardiographic reconstruction of the delineation of the right ventricle seen from the septal side (end-diastolic volume 153 ml, end-systolic volume 64 ml, and ejection fraction 58%). The mesh is the right ventricle at end-diastole, in green at end-systole. Pulmonary valve (PV) is shown in white in the upper left side, tricuspid valve (TV) is shown in the upper right side, and right ventricular (RV) apex toward the bottom. *shows the interventricular septum bulging into RV. Data were processed using a dedicated software (4D RV-Function, TomTec Imaging Systems). See also Video 1.

Figure 5

Example of delineation of a patient with pulmonary hypertension in end-diastole. Box, line, and color descriptions are the same as in Fig. 4. (A) The right ventricle is enlarged and the trabeculation is hypertrophied. Trabeculations are included in the volume. The septum is flattened, even in diastole, in the short-axis images. (B) The three-dimensional echocardiographic representation (end-diastolic volume 200 ml, end-systolic volume 137 ml, ejection fraction 31%) shows an enlarged right ventricle with a flattened septum in diastole (mesh) and even more so in systole (green). Both the longitudinal and lateral functions appear to be altered. Data were processed using a dedicated software (4D RV-Function, TomTec Imaging Systems). See also Video 2.

Figure 6

Example of semi-automated delineation of the right ventricle (A) without manual correction and (B) with manual correction. The endocardial contour detection (green) is enhanced in a basal short-axis view (magenta box, yellow, and purple lines as in Fig. 4A) from a three-dimensional dataset. The semi-automated delineation crosses, and hence includes, parts of the septum (*) in the right ventricular volume. On the other hand, the delineation does not follow the anterior part of the right ventricular outflow tract (RVOT) and that volume is excluded from calculation. See also Video 3.