Echo Reference — Diastolic Function & Haemodynamics
RV Size & Function
Right ventricular dimensions (quantitative and qualitative), RVOT measurements, wall thickness, PA diameter, systolic function parameters (TAPSE, S', FAC, free-wall strain, global strain, 3D RVEF, MPI), and RV diastolic function grading. Based on ASE 2025 Right Heart guidelines and WASE data.
RV Dimensions — Severity Grading
RV dimensions are measured from the RV-focused apical four-chamber view at end-diastole. Basal diameter is measured at the widest point of the basal third (at the level of the tricuspid annulus). Mid-cavity diameter is measured at the mid-level of the RV body, at the level of the LV papillary muscles.
| RV Diameter | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| Basal (cm) | < 4.1 | 4.1 – 4.4 | 4.5 – 4.9 | > 4.9 |
| Basal index (cm/m²) | < 2.4 | 2.4 – 2.6 | 2.7 – 2.9 | > 2.9 |
| Mid (cm) | < 3.5 | 3.5 – 3.8 | 3.9 – 4.2 | > 4.2 |
RV Outflow Tract (RVOT)
| RVOT | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| PLAX / RVIDD (cm) * | < 3.3 | 3.3 – 3.5 | 3.6 – 3.9 | > 3.9 |
| PSAX proximal (cm) * | < 3.4 | 3.4 – 3.8 | 3.9 – 4.1 | > 4.1 |
| PSAX distal (cm) # | < 2.9 | 2.9 – 3.0 | 3.1 – 3.3 | > 3.3 |
* RVOT variability: RVOT measurements can vary by up to 40% between the PLAX and PSAX proximal planes. The distal RVOT dimension (#) from the PSAX plane is less variable and more reproducible.
RV End-Diastolic Area & 3D Volume
| Parameter | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| 2D EDA (cm²) | < 25 | 25 – 28 | 29 – 32 | > 32 |
| Indexed EDA (cm²/m²) | < 14 | 14 – 15 | 16 – 17 | > 17 |
| 3D EDV (mL) | < 130 | 130 – 150 | 151 – 170 | > 170 |
| 3D Indexed EDV (mL/m²) | < 90 | 90 – 103 | 104 – 115 | > 115 |
RV Size — Qualitative Assessment
Qualitative RV size is assessed from the apical four-chamber view by comparing the RV cavity area to the LV and noting which ventricle forms the apex.
| Grade | RV:LV Relationship | Apex |
|---|---|---|
| Normal | RV area or mid-cavity diameter smaller than LV | Formed by LV |
| Mildly dilated | RV area increased (> 2/3 of LV but still smaller than LV) | Still formed by LV |
| Moderately dilated | RV cavity area similar to LV | RV may share the apex |
| Severely dilated | RV cavity area exceeds LV | RV forms the apex |
RV Wall Thickness & Pulmonary Artery
| Parameter | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| RV free wall — subcostal (cm) | < 0.5 | 0.5 – 0.7 | 0.8 – 0.9 | > 0.9 |
| Main PA diameter (cm) | < 2.5 | 2.5 – 3.0 | 3.1 – 3.5 | > 3.5 |
RV wall thickness: Measured at end-diastole from the subcostal view. RV free wall thickness ≥ 0.5 cm suggests RV hypertrophy. Common causes include pulmonary hypertension, pulmonary stenosis, and congenital heart disease.
RV Systolic Function — Severity Grading
Multiple parameters should be used to assess RV systolic function. No single measurement is sufficient — the ASE recommends integrating at least two parameters. TAPSE and S' are the most reproducible and routinely obtained.
| Variable | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| RV S' (cm/s) | > 9.5 | 9.5 – 7.2 | 7.1 – 5.1 | ≤ 5.0 |
| TAPSE (cm) | > 1.7 | 1.7 – 1.3 | 1.2 – 1.1 | ≤ 1.0 |
| 3D RVEF (%) | > 45 | 45 – 40 | 39 – 32 | < 32 |
| FAC (%) | > 35 | 35 – 30 | 29 – 23 | ≤ 22 |
| MPI — TDI | < 0.55 | 0.55 – 0.61 | 0.62 – 0.69 | ≥ 0.70 |
| MPI — PW | < 0.4 | 0.4 – 0.48 | 0.49 – 0.56 | ≥ 0.57 |
| RV free wall strain (%) | > 20 | 20 – 16 | 15 – 11 | < 11 |
| RV global strain (%) | > 17 | 17 – 14 | 13 – 10 | ≤ 9 |
TAPSE & S' limitations: Both TAPSE and S' measure longitudinal function of the RV free wall only and may be misleading after cardiac surgery (pericardial adhesions reduce longitudinal motion despite preserved global RV function). In post-surgical patients, FAC, 3D RVEF, or RV free-wall strain are more reliable.
RV strain convention: RV free-wall strain is reported as an absolute value (positive number). RV global strain includes the interventricular septum, which lowers the absolute value. Always specify which is being reported. Free-wall strain is the preferred measurement for RV assessment.
RV Diastolic Function
RV diastolic function is assessed using tricuspid inflow PW Doppler and tricuspid annular TDI. RV diastolic function is influenced by the systolic and diastolic function of the left heart — systemic blood pressure should also be reported.
| Variable | Normal | Impaired Relaxation | Pseudonormal * | Restrictive |
|---|---|---|---|---|
| E/A | 0.8 – < 2.0 | < 0.8 | 0.8 – 2.1 | > 2.1 |
| TV E/e' | > 0.6 | 0.6 – 7.3 | 7.4 – 8.4 | ≥ 8.5 |
| TV e'/a' | 0.5 – 1.7 | 1.8 – 2.1 | 2.2 – 2.4 | ≥ 2.5 |
| DT (ms) | 230 – 120 | 119 – 87 | 86 – 58 | ≤ 57 |
* Pseudonormal pattern: Hepatic vein Doppler should demonstrate diastolic dominance to support the pseudonormal classification. Without hepatic vein confirmation, it is difficult to distinguish normal from pseudonormal tricuspid inflow.
Clinical context: RV diastolic dysfunction is commonly seen with pulmonary hypertension, right heart failure, tricuspid regurgitation, and left heart disease. Always interpret RV diastolic parameters alongside LV diastolic function, pulmonary pressures, and volume status.
When to Use Which RV Parameter
Different clinical scenarios favour different RV parameters. No single measurement is universally reliable — the choice depends on the clinical context and the specific limitations of each parameter in that setting.
| Clinical Scenario | Recommended Parameters | Rationale |
|---|---|---|
| Post-cardiac surgery | FAC, 3D RVEF, RV free-wall strain | Pericardial adhesions reduce longitudinal motion — avoid relying solely on TAPSE/S' as they may underestimate global RV function |
| Pulmonary hypertension | TAPSE, TAPSE/PASP ratio, RV free-wall strain, 3D RVEF | TAPSE/PASP ratio assesses RV-PA coupling. Strain detects early subclinical dysfunction. 3D RVEF provides global assessment |
| Severe TR | FAC, 3D RVEF, RV free-wall strain | Avoid relying solely on TAPSE and S' — volume overload from severe TR can maintain or increase longitudinal motion despite deteriorating global RV function |
| Cardio-oncology | RV free-wall strain | Detects subclinical RV dysfunction before TAPSE or EF decline. Use for serial monitoring with consistent vendor platform |
| Pre-TAVI / pre-operative | 3D RVEF, FAC, TAPSE | Comprehensive baseline assessment. 3D RVEF provides the most accurate volumetric measurement when available |
| Acute PE | Qualitative RV size, TAPSE, McConnell's sign | Rapid bedside assessment. RV dilatation with TAPSE < 1.6 cm suggests RV pressure overload. Look for McConnell's sign |
RV-PA Coupling (TAPSE/PASP Ratio)
RV-pulmonary arterial coupling describes the relationship between RV contractile function and the afterload it faces. The TAPSE/PASP ratio provides a simple, non-invasive estimate. A low ratio indicates the RV is failing to compensate for elevated pulmonary pressures — a state of RV-arterial uncoupling.
| TAPSE/PASP | Interpretation |
|---|---|
| ≥ 0.36 mm/mmHg | Preserved RV-PA coupling |
| < 0.36 mm/mmHg | RV-arterial uncoupling — strong prognostic marker in heart failure and pulmonary hypertension |
Load dependence: This ratio relies on PASP estimation from TR velocity, which is itself subject to measurement error (incomplete envelope, non-parallel alignment, assumed RAP). Errors in PASP directly affect the ratio. Additionally, TAPSE/PASP is less reliable in severe TR, where both TAPSE (overestimated due to volume loading) and PASP (potentially underestimated with low-velocity TR jets) may be inaccurate.
Clinical value: Despite its limitations, TAPSE/PASP < 0.36 mm/mmHg is independently associated with worse outcomes in heart failure (both HFrEF and HFpEF), pulmonary hypertension, and after cardiac surgery. It is a simple ratio derived from two measurements that are already routinely obtained.
McConnell's Sign
McConnell's sign describes akinesia of the RV free wall with preserved (or hyperkinetic) apical contractility. It is a pattern seen on the apical four-chamber view and is classically associated with acute pulmonary embolism.
Specificity caveat: McConnell's sign is suggestive but not specific for acute PE. The same pattern can be seen in RV infarction and other causes of acute RV pressure overload. It should be interpreted in the clinical context — not used as a standalone diagnostic criterion. When present in the appropriate clinical setting (acute dyspnoea, haemodynamic compromise, elevated D-dimer), it supports the diagnosis of acute PE and should prompt further investigation.
Why the apex is spared: The RV apex is tethered to the LV apex and receives mechanical support through interventricular interaction. In acute RV pressure overload, the free wall dilates and becomes akinetic while the apical segment continues to contract — driven by LV apical contraction rather than intrinsic RV contractility.
Measurement Pitfalls
The RV's complex crescent-shaped geometry and heavy trabeculation make it more susceptible to measurement error than the LV. Consistent technique is critical for serial comparisons.
| Measurement | Pitfall | Impact |
|---|---|---|
| RV dimensions | Not using a true RV-focused apical view — standard A4C underestimates RV size | RV basal and mid dimensions will be falsely small. The RV-focused view maximises the RV cavity and must be used for all RV linear dimensions |
| TAPSE | M-mode cursor not aligned with the direction of tricuspid annular motion | Off-axis cursor underestimates TAPSE. Align with the longitudinal excursion of the lateral annulus |
| S' velocity | TDI sample volume not positioned at the tricuspid annulus | Placement into the myocardium or below the annulus gives falsely low velocities. Sample volume must be at the lateral tricuspid annular insertion |
| FAC | Not including trabeculations within the RV cavity when tracing endocardial border | Excluding trabeculations from the cavity reduces end-diastolic area and underestimates FAC |
| FAC | RV geometry assumption — FAC is a 2D single-plane measurement | FAC underestimates dysfunction in regional wall motion abnormalities (e.g. RV infarction affecting segments not captured in the A4C plane) |
| RV strain | Poor tracking quality of RV free wall due to thin myocardium and trabeculation | Manual adjustment of tracking points may be needed. Reject segments with poor tracking rather than accepting inaccurate values |
| 2D vs 3D | 2D methods systematically underestimate RV volumes compared to 3D and CMR | The RV's non-geometric shape is poorly approximated by 2D planes. 3D echo provides more accurate volumetric assessment when image quality permits |
Best practice: Always obtain a dedicated RV-focused apical view (not just the standard A4C). Use at least two parameters to assess RV systolic function, choosing parameters appropriate to the clinical context. For serial studies, use the same method consistently.
References
- Mukherjee M, et al. Guidelines for the Echocardiographic Assessment of the Right Heart in Adults and Special Considerations in Pulmonary Hypertension: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2025;38(3):141–186.
- Lang RM, et al. Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr. 2015;28:1–39.
- Mitchell C, et al. Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019;32(1):1–64.