Fig. 11.1
Measurements of RV dimensions. The RV basal (D1) and mid cavity (D2) dimensions are shown in the RV focused apical four-chamber view (a). Measurements of the right ventricular outflow tract (RVOT) at the proximal level and at the distal level are shown in the parasternal short-axis (b) and parasternal basal long-axis (c)
Also, in patients with long standing pulmonary hypertension, RV dysfunction and tricuspid valve regurgitation might remain well established and irreversible. Therefore, imaging of the RV should be directed towards RV enlargement, TV annulus dilatation and RV function.
Imaging Modalities for Assessment of RV Function and Size, and Tricuspid Annulus Size
Echocardiography
In every echocardiographic examination, RV size and function should be assessed at the time of the first diagnosis and during serial follow up, particularly in patients with chronic diseases and heart failure. Guidelines for the echocardiographic evaluation of the RV have been published for the adult population and emphasize the importance of 2D multiple views for the assessment of the entire RV and to distinguish the different RV segments, including the apical views as well as the parasternal long-axis and short-axis views and subcostal view. The RV dimensions are best estimated from a RV-focused apical four-chamber view obtained with either lateral or medial transducer orientation. Care should be taken to avoid foreshortening of the RV. Reference values for the adult population are reported in the echocardiographic guidelines for cardiac chamber quantification by the American Society of Echocardiography and the European Association of Cardiovascular Imaging [12] (Table 11.1). The tricuspid annulus dimensions are measured in end-diastole and end-systole in an apical four-chamber view.
Table 11.1
Reference value for right atrial and ventricular size and function, and TV annulus for echocardiography and CMRa
Abnormal | ||
|---|---|---|
Women | Men | |
Echocardiography | ||
RA minor axis dimension (cm/m2) | >2.5 | >2.5 |
RA major axis dimension (cm/m2) | >3.1 | >3.0 |
2D echocardiographic RA volume (ml/m2) | >33 | >39 |
RV diameter | ||
– Basal diameter (mm) | >41 | >41 |
– Mid diameter (mm) | >35 | >35 |
– Longitudinal diameter (mm) | >83 | >83 |
– RVOT PLAX diameter (mm) | >30 | >30 |
– RVOT proximal diameter (mm) | >35 | >35 |
– RVOT distal diameter (mm) | >27 | >27 |
– Wall thickness (mm) RVOT, right ventricular outflow tract | >5 | >5 |
RV volume | ||
– EDV indexed to BSA (ml/m2) | >74 | >87 |
– ESV indexed to BSA (ml/m2) | >36 | >44 |
RV systolic function | ||
– TAPSE (mm) | <17 | <17 |
– Pulsed Doppler S′ wave (cm/sec) | <9.5 | <9.5 |
– Color Doppler S wave (cm/sec) | <6.0 | <6.0 |
– RV fractional area change (%) | <35 | <35 |
– RV 3D EF (%) | <45 | <45 |
TV annulus | ||
– Diameter at end-systole (cm) | >3.4 | >3.4 |
– Diameter at end-systole indexed to BSA (cm/m2) | >1.9 | >1.7 |
– Diameter at end-diastole (cm) | >3.9 | >3.9 |
– Diameter at end-diastole indexed to BSA (cm/m2) | >2.2 | >2.0 |
Cardiovascular magnetic resonance | ||
– EDV indexed to BSA (ml/m2) | >76 | >91 |
– ESV indexed to BSA (ml/m2) | >29 | >40 |
– EF (%) | <57 | <52 |
RV Function
RV systolic function can be evaluated by using multiple parameters, including TAPSE, 2D RV Fractional Area Change (FAC), 3D echocardiography, and longitudinal strain and strain rate by Doppler Tissue Imaging (DTI) and 2D speckle tracking.
A simple and very attractive tool for measuring systolic long-axis motion of the RV free wall or tricuspid annular plane systolic excursion (TAPSE) in the apical four-chamber view is the two dimensional guided M-mode, which has a good correlation with ejection fraction derived by radionuclide angiography (Fig. 11.2). Moreover, it has been demonstrated to be valuable in ischemic heart disease and cardiomyopathy. The main limitation of this method is that it only represents the longitudinal shortening of the RV lateral wall, thus excluding the RV outflow tract and septal contribution to the overall function of the right heart. Furthermore, in patients with dilated cavity and volume overloaded right ventricles as is the case in the presence of tricuspid regurgitation, TAPSE can erroneously overestimate RV function.
Fig. 11.2
Measurements of the tricuspid annular plane excursion (TAPSE) in a patients with normal RV function (a) and in a patients with RV dysfunction due to pulmonary hypertension (b)
Right ventricular fractional area change (RV FAC) has been shown to correlate with RV Ejection Fraction (EF) calculated by CMR and is an independent predictor for outcome after myocardial infarction (Fig. 11.3). RV FAC provides an estimation of the global RV systolic function. However, poor image quality and visualization of the endocardial borders are often limiting this technique, especially in the RV lateral wall and RV apex.
