Table 2. Summary of echocardiography imaging techniques.

Parameters	Recommended methods (values RV failure)	Strengths	Limitations	Mortality
Assessment of RV size
Size Linear dimensions    2D volumes	RV focused 4CV	• Easy to perform • Fast and simple • Base RV diameter always • Mid RV diameter and RV length only in right-sided disease	• Underestimated as opposed to cardiac CMR (geometric model) due to crescent shape -> 3D (9) • Dependent on probe rotation and different RV views • Suboptimal image quality of RV free wall • Presence of trabeculations • Assessment of ventricular volumes and function: unsatisfying in sRV and UVH (unique geometry)	LV/RV ratio predictor of adverse clinical events and/or hospital survival in patients with acute PE (22)
	Base (>42 mm)
	Mid – level (>35 mm)
	Longitudinal (>53 mm) ED
	LV/RV ED ratio =1.3 (9)
	ED and ES
RV free-wall thickness	Subcostal 4CV, zoomed imaging	• Easy to perform	• Single – site measurement • No criterium for abnormal thin RV wall • Excluding RV trabeculations and papillary muscle from RV endocardial border is critical • Lack of established prognostic information • Oblique M-mode may overestimate RV wall	Prognostic value unknown
	ED, M-mode or 2D [RV free lateral wall >5 mm (9)]
RVOT	• RVOT proximal: • anterior RV wall - IVS (PLAX) or - aortic valve (PSAX) ED • RVOT distal: measured just proximal to the PV at ED • RVOT dilatation: • RVOT proximal PLAX >33 mm • RVOT Distal PSAX >27 mm	• Simple • Fast	• RVOT proximal: imaging plane position and less reproducible than RVOT distal • Underestimation or overestimation if the RV view is obliquely oriented • Endocardial definition of the RV anterior wall is often suboptimal • Limited data are available
3D	3D volumes	• Calculates 3D volumes (no geometric assumptions) • Independent of the RV exact shape • Correlates with CMR measurements	• Special transducer, dedicated hardware and software • Higher cost • Additional time to perform • Good image quality • Patient cooperation • 3D training • Only few data on reference values available	Independent predictor of adverse cardiovascular outcome (18)
Assessment of RV function
RV longitudinal systolic function
TAPSE	Apical 4CV	• Validated against radionuclide EF	• 1D measurement • Only global RV function • Angle – dependent • Does not reflect true RVEF in patients with TOF and TR	Low TAPSE is associated with lower CI and worse survival (23,24) TAPSE/SPAP is a good predictor of survival (25)
	Maximum systolic excursion of the lateral tricuspid annulus (M-mode) between ED and peak systole (<16 mm)
Tissue doppler of the free lateral wall (S’)	Longitudinal velocity of the tricuspid annular plane (S’ value <0.095 m/s)	• Reproducible • Validated against radionuclide EF • Good correlation with CMR-derived RVEF	• Angle – dependent • Small subsection of the RV • Not to apply in case of regional wall-motion abnormalities	Established prognostic value
	Pulsed tissue doppler
Global Longitudinal strain (GLS) (RV free wall)	% systolic shortening of the RV free wall	• Regional and global function • Sensitive tool for identifying initial RV dysfunction • Highly reproducible • Angle – independent • Less load-dependent • Best correlation with CMR • Information over the whole myocardium thickness • Correlates with RV SVI, RA pressure and RVEF	• Vendor and software dependent • RV size and shape • Image quality • Load – dependent (less than PW and TDI) • Strain rate (velocity) is less accurate than time – integrated measures such as strain • RV free wall GLS corresponds better with RV mechanical function than RV global strain (which includes IVS and is part of both ventricles) • In patients with AF: average of 3 heart cycles	Excellent predictor of outcome (11) and survival in PAH-patients (26)
	Average peak systolic strain of the 3 segments of the free lateral wall
Strain rate
	RV focused 4CV (>−20%)
	Rate of this shortening
RV global systolic function
FAC	100x (RVED - RVES)/RVED	• Good correlation with CMR derived RVEF • Reflects both longitudinal and radial contraction	• Image quality, delineation between endocardium and trabeculations • Contribution of RVOT to overall systolic function	Independent predictor for mortality/HF/sudden death/stroke after myocardial infarction, post-cardiac surgery, PAH-patients
	RV focused 4CV (<35%)
3D RVEF	Fractional RV volume change	• Reliable • Reproducible • Best correlation with CMR • Includes RVOT contribution to overall function	• Image quality • Load dependency • Requires offline analysis and experience	Prognostic value not established
	RF EF (%) =100x(EDV-ESV)/EDV (RVEF <45%)
RIMP (Tei index)	Tissue doppler velocities or pulse wave velocities from the RV (IVRT – IVCT)/RV ejection time (PW doppler >0.43) (TDI >0.54)	• Do not require full visualization of the RV	• Irregular heart rates • RA pressure is elevated (IVRT is decreased)	Prognostic value not established
RV diastolic function
Doppler E/A ratio	Apical 4CV • tricuspid E/A ratio <0.8: impaired relaxation • tricuspid E/A ratio 0.8–2.1 + E/E’ratio >6 or diastolic flow predominance in the hepatic veins: pseudonormal filling • tricuspid E/A ratio >2.1 + deceleration time <120 ms: restrictive filling (as does late diastolic antegrade flow in the PA	• Tissue doppler is less load dependent • Clinically useful • Tricuspid E/E’ ratio and RA volume have been shown to correlate well with hemodynamic parameters • Early and more easily quantifiable marker of subclinical RV dysfunction (even before RVH, RV systolic dysfunction, RV dilatation)	• Effects of age, respiration, heart rate and loading conditions	Independent predictor of mortality (27)
Doppler E/E’ ratio    presence of late diastolic antegrade flow in the PA
RA size (RA dimensions and area)	Single-plane area-length or disk summation techniques in an apical view	• Markers of RA dilatation - sign of volume - or pressure overload • More accurate than compared with linear dimensions • Easily obtained • RA area better indicator for RV diastolic dysfunction	• Underestimated with 2D compared with 3D • Assumes symmetrical shape of the cavity • Normal values not well established • Single plane volume calculation may be inaccurate (RA enlargement is symmetrical) • RA area more time-consuming	Elevated RA pressure is a predictor for mortality
	End – diastole/4CV (normal value: women: 21 +/- 6 mL/m2 and for men 25 +/- 7 mL/m2)
	[RA length (>53 mm) and RA diameter (>44 mm)]
Hepatic veins + measurement of IVC size and collapsibility	Pulsed Doppler Low or normal RA pressure: Vs > Vd Elevated RA pressure: Vs/Vd <1 • Hepatic vein systolic filling fraction = Vs/(Vs+Vd) <55%: elevated RA pressure • Normal RA pressure of 3 mmHg (0–5 mmHg): IVC diameter <21 mm + collapses >50% • Intermediate value: 8 mmHg (range, 5–10 mmHg): <21 mm and <50% collapse or >21 mm with >50% collapse • High RA pressure of 15 mmHg (range, 10–20 mmHg): >21 mm + collapses <50%	• Easily obtained from subcostal window	• IVC collapse cannot be used to estimate RA pressure in ventilated patients • Hepatic vein flow velocities have been validated in mechanically ventilated patients	Prognostic value unknown
RA pressure
RVSP pulmonary systolic pressure	TV velocity >2.8–2.9 m/s = SPAP 36 mmHg (RA pressure 3–5 mmHg)		• No significant RVOT obstructions • Recommended to use the RA pressure estimated from IVC rather than arbitrarily assigning a fixed RA pressure • SPAP increase with age and obesity • Elevated SPAP may not always indicate elevated PVR • Influenced by the systolic and diastolic function of the left heart	Prognostic value unknown

1D, one dimensional; 2D, two dimensional; 3D, three dimensional; 4CV, four chamber view; AF, atrial fibrillation; CMR, cardiac magnetic resonance imaging; CI, cardiac index; ED, end diastolic; EF, ejection fraction; ES, end systolic; FAC, fractional area change; GLS, global longitudinal strain; HF, heart failure; IVS, interventricular septum; IVRT, isovolumic relaxation time; IVCT, isovolumic contraction time; LV, left ventricle; PA, pulmonary arteria; PAH, pulmonary arterial hypertension; PAT, pulmonary acceleration time; PE, pulmonary embolism; PLAX, parasternal long axis view; PSAX, parasternal short axis view; PVR, pulmonary vascular resistance; PW, pulsed wave; RA, right atrium; RIMP, right ventricular index of myocardial performance; RV, right ventricle; RVED, right ventricle end diastole; RVEF, right ventricular ejection fraction; RVES, right ventricle end sysole; RVH, right ventricular hypertrophy; RVOT, right ventricular outflow tract; RVSP, RV systolic pressure; sRV, systemic right ventricle; SPAP, systolic pulmonary artery pressure; SVI, stroke volume index; TAPSE, tricuspid annular plane systolic excursion; TDI, tissue Doppler imaging; TOF, tetralogy of Fallot; TR, tricuspid valve regurgitation; UVH, univentricular heart; Vs, systolic hepatic vein flow; Vd, diastolic hepatic vein flow.