RV dysfunction is the independent predictor of unfavourable prognosis in patients with heart failure and has been also described as the determinant of long-term survival and the independent predictor of poor clinical status in patients with repaired TOF [7]. In clinical practice, probably the most commonly used parameters of RV size and contractile function are RV volumes and RV ejection fraction (EF). Although widely accepted, RVEF is highly dependent on loading conditions. The 2D echocardiographic methods of measuring RVEF include area-length methods, disc summation methods and other methods. The area-length methods require geometric assumption, most commonly based on modified pyramidal or ellipsoidal models. The disc summation method mainly determines an RV “body” volume, using the apical four-chamber view. RV volumes are therefore underestimated because it excludes the infundibulum that accounts for as much as 25–30 % of RV volume. RV EF from 2D methods is calculated as (end-diastolic volume—end-systolic volume)/end-diastolic volume. RVEF can vary from 40 to76 % depending on the type of modality used. Currently, MRI is the gold standard for calculating RV volumes and EF. The normal value of MRI-derived RVEF is 61 ± 7 %, ranging from 47 to 76 %. The 2D echocardiographic methods of assessing RV volume and RVEF are less accurate because of the complex geometry of RV. The correlation between RVEF by echocardiography and MRI-determined RVEF is weak to moderate in normal individuals (r = 0.15–0.54), in pulmonary embolism and repaired TOF (r = 0.33–0.61) and myocardial infarction and atrial septal defect (r = 0.32–0.85) [8, 9]. Therefore, based on the guideline for the echocardiographic assessment of the right heart published in 2010 by the ASE and the EACVI, 2D-derived assessment of RV EF is not recommended because of the heterogeneity of methods and the geometric assumptions [1].

Right ventricular fractional area change (RVFAC) is defined as (RV end-diastolic area—RV end-systolic area)/RV end-diastolic area. The RVFAC is a simple and independent of geometric assumption method of assessing RV function. RVFAC has been shown to have prognostic significance in patients with myocardial infarction, pulmonary embolism and PH [10]. FAC is obtained in the apical four-chamber view by tracing the RV endocardium both in systole and diastole from the annulus, along the RV free wall to the apex and then along the interventricular septum back to the annulus (Fig. 4.3). It is important that the entire RV should be contained in the imaging, including the apex and the RV free wall, during both systole and diastole. Care must be taken to trace the free wall beneath the trabeculations. Compared with other 2D echocardiographic measures of RV systolic function [including tricuspid annular plane systolic excursion (TAPSE, r = 0.17) and transversal fractional shortening (r = 0.12)], RVFAC was best correlated with CMR-derived EF (r = 0.80). Accurately tracing RV systolic and diastolic endocardial border is an important factor that impacts on measuring RVFAC. Suboptimal RV endocardial definition limits the accuracy and reproducibility of RVFAC [11]. Based on the guideline for the echocardiographic assessment of the right heart published in 2010 and recommendations for echocardiographic chamber quantification published in 2015 by the ASE and the EACVI, two-dimensional RVFAC is one of the recommended methods of estimating RV function. RV FAC <35 % indicates RV systolic dysfunction [1, 2].

The rate of pressure rise in the ventricles (dP/dt) is also used as an index of ventricular contractility or systolic function. RV dP/dt can be measured on the ascending limb of the TR continuous-wave Doppler signal. It is commonly calculated by measuring the time required for the TR jet to increase in velocity from 1 to 2 m/s. Using the simplified Bernoulli equation, this represents a 12 mmHg increase in pressure. RV dP/dt is therefore calculated as 12 mmHg divided by this time (in seconds). Although the time from 1 to 2 m/s is most commonly used, the best correlation between echocardiographic and invasive measures was found by using the time from 0.5 to 2 m/s. RV dP/dt is load dependent. It will be less accurate in severe tricuspid regurgitation. Based on the guideline for the echocardiographic assessment of right heart published in 2010 by the ASE and the EACVI, RV dP/dt cannot be recommended for routine uses. It can be used in patients with suspected RV dysfunction. RV dP/dt < approximately 400 mmHg/s is likely abnormal [1, 2].

Myocardial performance index (MPI), also known as the RIMP or Tei index, is defined as the ratio of sum of isovolumic contraction time (IVCT) and isovolumic relaxation time (IVRT) divided by ejection time (ET) or [(IVRT + IVCT)/ET]. It is an index of RV global performance, incorporating both measures of systolic and diastolic function [12]. The MPI increases in cases of RV dysfunction. The MPI can be obtained by two methods: the pulsed Doppler method and the tissue Doppler method [13, 14]. In the pulsed Doppler method, time intervals can be determined from two different cardiac beats. The ejection time can be obtained from the pulsed Doppler of RV outflow (time from the onset to the cessation of flow), while isovolumic intervals are determined based on the tricuspid flow. The tricuspid (valve) closure-opening (TCO) time is measured with either pulsed Doppler of the tricuspid inflow (time from the end of the transtricuspid A wave to the beginning of the transtricuspid E wave) or continuous Doppler of the TR jet (time from the onset to the cessation of the TR jet) (Fig. 4.4a). TCO time includes isovolumic contraction time, ejection time and isovolumic relaxation time. In the tissue Doppler method, the ejection time (time from the onset to the cessation of the S′ wave) and TCO time (time from the end of the A′ wave to the beginning of the E′ wave) can be measured from a single beat by pulsing the tricuspid annulus. The MPI has shown to be a predictor of poor prognosis in disease associated with PAH [15]. Its prognostic value was also demonstrated in congenital heart disease, myocardial infarction, hypertrophic cardiomyopathy, dilated cardiomyopathy and chronic respiratory diseases [15–17]. Chockalingam et al. demonstrated that RV MRI has high sensitivity (82 %) and specificity (95 %) for the diagnosis of RV myocardial infarction and decreased after thrombolysis [12]. An advantage is that MPI is independent of loading conditions, heart rate and geometric assumptions. Moreover, the MPI is a feasible and reproducible parameter of RV global performance. The MPI has been demonstrated to be unreliable when time intervals were obtained from different R-R intervals, as in atrial fibrillation. In addition, it is subjected to pseudonormalization due to a shortened isovolumic relaxation time when RA pressure is elevated (such as RV myocardial infarction). The MPI may be used for initial and serial assessment of RV function in complement with other quantitative and nonquantitative measurement as shown by the recommendations for echocardiographic chamber quantification published in 2015 by the ASE and the EACVI [2]. The upper reference limit is 0.43 using the pulsed Doppler method and 0.54 using the tissue Doppler method.

The complex anatomy of RV is clearly displayed using 3D reconstruction techniques. Therefore, the quantification of RV volume and function for clinical use may represent the most justified application of three-dimensional echocardiography (3DE), as the awareness of two-dimensional echocardiography (2DE) shortcomings in this regard and the advancements in ultrasound technology are fastly growing. However, the clinical application of the conventional 3DE is limited due to time-consuming images acquirement and data analysis. The recent introduction of real-time three-dimensional echocardiography (RT3DE) offered a great progress in echocardiography as images may be obtained in just one beat. Good correlation between RT3DE and CMR for measuring RV volumes and EF was reported [18, 19]. RT3DE-determined RVEF correlated well with RVEF measured by radionuclide techniques [20]. The accuracy of RV volumes on 3DE has been validated against animal specimens, animal models of the RV and human intraoperative RV volume measurement. Compared with CMR data, RV volumes obtained from 3DE showed significantly better agreement and lower intra- and interobserver variability than 2DE.

During analysis of RV volume, it is important to manually define end-diastolic and end-systolic frames using maximal and minimal RV volumes, respectively. The moderator band and myocardial trabeculae should be included in the cavity (Fig. 4.5).

RT3DE not only can adequately assess RV function in the subset of PH patients, but also enables unique views to outline and better understand particular causes of PH, such as septal defects or complex congenital pathology. RT3DE also provides new insight into mechanisms of tricuspid valve regurgitation in patients with hypoplastic left heart syndrome. The feasibility and usefulness of RT3DE for RV quantitation have also been demonstrated in patients with arrhythmogenic right ventricular dysplasia and congenital heart disease. Images may be obtained by transesophageal echocardiography (TTE) and transthoracic echocardiography (TEE). The accuracy of TTE-3D was comparable to that of TEE-3D. RT3DE seems to be superior to conventional 2DE owing to accurate volume analysis independent of RV size and shape, without foreshortened views and geometric assumptions. The drawbacks of this method include patient’s inability to cooperate for breathhold, arrhythmias, the larger footprint and size of matrix-array transducer and dependence on optimal acoustic quality [21–26]. 3DE-obtained RV volume and EF should be recommended in laboratories with appropriate 3D platforms and experience, and an RV EF of <45 % usually suggested abnormal RV systolic function. Current data indicate that the upper reference limit for RV EDV is 87 mL/m² in men and 74 mL/m² in women and for RV ESV is 44 mL/m² for men and 36 mL/m² for women [2].

TAPSE is a method to obtain the systolic excursion of the RV annular segment along its longitudinal plane, from the standard apical four-chamber view by placing an M-mode cursor through the tricuspid lateral annulus and measuring the peak excursion of longitudinal motion of the annulus at systole (Fig. 4.6). It represents RV longitudinal function. This index assumes that the displacement of the basal segments in the apical four-chamber view is representative of the entire RV function, which can be invalid when regional RV wall motion abnormalities exist; otherwise, it has been shown to have a good correlation with RVEF assessed by radionuclide angiography. TAPSE is related to RV-decreased systolic function in patients with acute pulmonary embolism and a predictive factor in patients with heart failure and PAH. Although TAPSE is simple, widely available and reproducible and does not require geometric assumption, it is angle dependent. TAPSE only assesses longitudinal motion of RV basal segment and does not represent the complex motion of the entire RV. Moreover, TAPSE takes no account of the outlet and the septal contribution to RV ejection, which is also important to maintain overall RV function. Because of load dependency, TAPSE may be less accurately representative of RV systolic function in case of significant tricuspid regurgitation [26–28]. Nevertheless, TAPSE should be used routinely as a simple method of estimating RV function. TAPSE < 17 mm indicates RV systolic dysfunction [2].