Echocardiographic Findings Suggesting Pulmonary Hypertension
When pulmonary hypertension is suspected on echocardiography, the diagnosis must be confirmed with right heart catheterization before initiating any PH-specific treatment 1, 2.
Key Echocardiographic Findings
The primary echocardiographic assessment relies on peak tricuspid regurgitation velocity (TRV) combined with additional structural signs to determine the probability of PH 1:
Probability Assessment Algorithm
High probability of PH:
- TRV 2.9-3.4 m/s without other PH signs, OR
- TRV >3.4 m/s (regardless of other signs)
Intermediate probability of PH:
- TRV ≤2.8 m/s or not measurable with presence of other PH signs
Low probability of PH:
- TRV ≤2.8 m/s or not measurable without other PH signs
Additional Echocardiographic Signs of PH
These signs are categorized into three anatomical groups 1:
Ventricular changes:
- RV/LV basal diameter ratio >1.0
- Flattening of interventricular septum (LV eccentricity index >1.1 in systole and/or diastole)
Pulmonary artery changes:
- RV outflow tract acceleration time <105 msec and/or midsystolic notching
- Early diastolic pulmonary regurgitation velocity >2.2 m/sec
- PA diameter >25 mm
IVC and right atrial changes:
- IVC diameter >21 mm with decreased inspiratory collapse (<50% with sniff or <20% with quiet inspiration)
- Right atrial area (end-systole) >18 cm²
Critical Limitations of Echocardiography
Echocardiography alone cannot support treatment decisions for PH 1. While it shows high correlation with invasive measurements across patient cohorts, significant overestimation and underestimation occur in individual patients with poor levels of agreement 3, 4. The technique should be considered a screening tool for assessing the likelihood rather than definitive presence or absence of PH 3, 4.
Next Diagnostic Step
Right heart catheterization is mandatory for:
- Confirming the diagnosis of PH (defined as mean PAP ≥25 mmHg at rest) 2, 4
- Accurate classification of PH type (pre- vs. postcapillary)
- Measuring pulmonary vascular resistance
- Guiding treatment decisions 1, 2
Additional Workup to Perform Concurrently
While arranging RHC, complete the diagnostic evaluation with:
- Pulmonary function tests with DLCO - to assess for underlying lung disease 1
- High-resolution chest CT - to evaluate for interstitial lung disease, emphysema, or chronic thromboembolic disease 1
- Ventilation/perfusion scan - if chronic thromboembolic PH is suspected
- Overnight oximetry or polysomnography - given 70-80% prevalence of nocturnal hypoxemia and sleep apnea in PAH 1
- 6-minute walk test - for functional assessment and prognostic information 4
Common Pitfalls to Avoid
- Do not initiate PH-specific therapy based on echocardiography alone - this can lead to inappropriate treatment with potentially harmful medications 1
- Do not rely solely on estimated pulmonary artery systolic pressure - the correlation is poor for individual patients despite population-level correlations 3
- Do not skip RHC in patients with intermediate or high probability - accurate hemodynamic classification is essential for proper management 2