Pulmonary Hypertension Grading on Echocardiography
Pulmonary hypertension probability on echocardiography is graded into three categories based on peak tricuspid regurgitation velocity (TRV): low probability (TRV ≤2.8 m/s), intermediate probability (TRV 2.9-3.4 m/s), and high probability (TRV >3.4 m/s), with additional echocardiographic signs from at least two different categories required to upgrade the probability level. 1, 2
Primary Grading System
The ESC/ERS guidelines establish a three-tier probability system that relies primarily on TRV measurements rather than calculated pulmonary artery systolic pressure (PASP), as TRV avoids the cumulative errors inherent in derived variables 1:
Low Probability of PH
- TRV ≤2.8 m/s (corresponding to PASP ≤36 mmHg assuming normal right atrial pressure) 2
- No additional echocardiographic signs of PH present 1
Intermediate Probability of PH
- TRV 2.9-3.4 m/s (corresponding to PASP 37-50 mmHg) 2
- OR TRV ≤2.8 m/s with additional echocardiographic signs present 1
High Probability of PH
- TRV >3.4 m/s (corresponding to PASP >50 mmHg) 1, 2
- OR TRV 2.9-3.4 m/s with additional echocardiographic signs present 1
Additional Echocardiographic Signs
Signs from at least two different categories must be present to alter the probability level when TRV is in the intermediate range or unmeasurable 1, 2:
Category A: Ventricular Assessment
- Right ventricle/left ventricle basal diameter ratio >1.0 2
- Flattening of the interventricular septum (leftward septal bowing in systole) 2
Category B: Pulmonary Artery Assessment
- Right ventricular outflow tract Doppler acceleration time <105 msec and/or midsystolic notching 2, 3
- Early diastolic pulmonary regurgitation velocity >2.2 m/s 2
- Main pulmonary artery diameter >25 mm 2
Category C: Right Atrium and IVC Assessment
- Inferior vena cava diameter >21 mm with decreased inspiratory collapse (<50% with sniff or <20% with quiet inspiration) 2
- Right atrial area (end-systole) >18 cm² 2
Right Atrial Pressure Estimation
RAP estimation is based on IVC characteristics, though this introduces measurement error 1:
- IVC <2.1 cm with >50% collapse on sniff: RAP = 3 mmHg (range 0-5 mmHg) 1
- IVC >2.1 cm with <50% collapse on sniff or <20% on quiet inspiration: RAP = 15 mmHg (range 10-20 mmHg) 1
- Intermediate scenarios: RAP = 8 mmHg (range 5-10 mmHg) 1
Clinical Management Based on Echo Probability
For Symptomatic Patients WITHOUT Risk Factors 1, 2:
- Low probability: Consider alternative diagnoses 1, 2
- Intermediate probability: Further investigation of PH may be considered 1
- High probability: Further investigation including right heart catheterization is recommended 1, 2
For Symptomatic Patients WITH Risk Factors for PAH/CTEPH 1, 2:
- Low probability: Echo follow-up should be considered 1, 2
- Intermediate probability: Further assessment including RHC should be considered 1, 2
- High probability: Further investigation including RHC is recommended 1, 2
Critical Pitfalls to Avoid
Do not use calculated PASP as the primary variable for grading PH probability—use peak TRV instead, as RAP estimation errors amplify inaccuracies in derived pressure calculations 1.
Severe tricuspid regurgitation significantly underestimates TRV and cannot be used to exclude PH, as the simplified Bernoulli equation becomes invalid 1. In these cases, rely more heavily on additional echocardiographic signs from multiple categories 1.
A single TRV measurement cannot reliably define or exclude PH—Doppler-derived pressure estimation may be inaccurate in individual patients, with both overestimation and underestimation occurring commonly 1. The full clinical context and additional echocardiographic variables must always be considered 2.
Exercise Doppler echocardiography is not recommended for PH screening (Class III recommendation) due to lack of validated criteria and prospective confirmatory data 2.
When TRV is technically difficult to measure due to trivial or mild tricuspid regurgitation, contrast echocardiography with agitated saline may improve the Doppler signal quality 1, 2.
Right heart catheterization remains the only definitive diagnostic test for PH—echocardiography alone is insufficient to support treatment decisions when PH-specific therapy is being considered 1, 2.