One should keep in mind that the right ventricle consists of 3 parts, the inflow, the outflow and the trabecular part, that all parts should be visualized. The outflow part is best seen in the parasternal long axis view . In this view the abnormal position of the interventricular septum can be seen. The left ventricle, aortic valve and mitral valve can be evaluated (Fig. 12.2a).

This view can be obtained by tilting the probe to scan more anteriorly. The right ventricle inflow part can be visualized. This is the only view in which the right anterior (free) wall can be visualized completely, in order to assess the hypertrophic right anterior free wall and its systolic function. (Fig. 12.2b). The diaphragmatic, inferior right ventricular wall can also be seen.

In order to evaluate the pulmonary valve the two most used views are the parasternal long axis view and short axis view. The long-axis view (Fig. 12.2c) is obtained by tilting the probe more cranial. In the parasternal short axis view (Fig. 12.2d), the infundibular portion or outflow portion of the right ventricle can be evaluated to assess whether a right ventricular outflow obstruction or pulmonary valve stenosis is present. Quantification of the severity of the obstruction can be done using continuous wave Doppler .

The parasternal short axis at the level of the papillary muscles evaluates the mid segments of the left and right ventricle (Fig. 12.2e).

Progression of right ventricle pressure causes thickening of the wall and dilation of the lumen.

The pressure loaded right ventricle loses its crescent, banana-shape, configuration and becomes more spherical and dilated. The wall is thickened. The interventricular septum shows systolic flattening, which causes the left ventricle to get a typical D-shape in this view. This septal flattening can be quantified by the eccentricity index , which is the ratio of the left ventricular diameter perpendicular to the septum and the orthogonal diameter of the left ventricle at the same level. This index changes from 1 (normal) to >1 in elevated right ventricular systolic pressures. An index >1.0 is therefore one of the secondary echocardiographic signs of pulmonary hypertension. An index >1.7 denotes a poor prognosis.

Diastolic interventricular septal flatting can be seen in severe tricuspid valve regurgitation as a sign of volume overload.

Eccentricity index = D1/D2

The inflow of the right and left ventricle can be evaluated in the 4-chamber view , which further allows the comparison of the right and left ventricular dimensions. The ratio of the basal right to left ventricular diameters. >1.0 is a secondary sign of PHT (Fig. 12.2f). For a realistic measurement of these diameters one should avoid foreshortened images by placing the ultrasound probe on the apex of the heart. In some cases this can be challenging and difficult to accomplish.

Right atrial dilation is often present in the presence of PHT. In the apical 4-chamber view the maximal right atrial area (mid-systole) can be measured. A right atrial area >18 cm² is indicative of right atrial dilatation and >27 cm² indicates a poorer prognosis.

The tricuspid valve is an anatomical structure belonging to the right ventricle. It consists of 3 valve leaflets which are kept in place by chordae, which on their part are mostly attached to the anterior papillary muscle. Chordae are also attached directly to the septum and to many smaller medial and inferior papillary muscles. The normal tricuspid valve annulus is an oval structure, with its largest diameter in the anterior to posterior direction. The tricuspid valve does not lie in one plane: the septal part is more cranially displaced in the perimembraneus region and the postero-septal region near the opening of the coronary sinus is lying more apically. During the cardiac cycle the annular area changes with a maximum area change during mid-diastole with the largest change in the septal to lateral axis. In diastole the annular plane is round and flat, while in systole the annulus becomes more oval and the curvature increases [3].

In the setting of right ventricular remodeling by pressure overload in PHT the morphology of the tricuspid valve changes. Dilation of the annulus is dominantly in the septal to lateral axis making the annular area larger, more round, and more planar during systole. As a consequence, a loss of leaflet coaptation area occurs. Additionally, right ventricle dilatation leads to a change in the geometry of the sub-valvular apparatus causing tenting of the valve leaflets. In Fig. 12.3a, b schematic drawing shows these changes.

As stated before it is important to realize that pulmonary artery pressure is dependent on left atrial pressure, pulmonary vascular resistance and pulmonary blood flow (cardiac output created by the right ventricular pump). During echocardiography , focus should lie on these parameters in order to understand and report the state of the pulmonary circulation completely.

In case of right ventricular outflow tract obstruction or pulmonary valve stenosis the estimated

systolic right ventricular pressure is not equal to the systolic pulmonary artery pressure.