How do you measure right ventricle (RV) systolic pressure using an echocardiogram (echo) image?

Measuring RV Systolic Pressure with Echocardiography

RV systolic pressure is measured by applying the simplified Bernoulli equation (ΔP = 4V²) to the peak velocity of the tricuspid regurgitation jet obtained by continuous-wave Doppler, then adding an estimate of right atrial pressure. 1

Step-by-Step Measurement Technique

1. Identify Tricuspid Regurgitation

• Use multiple acoustic windows (apical four-chamber, parasternal views, subcostal) to identify tricuspid regurgitation with color Doppler 1
• Tricuspid regurgitation is present in 65-75% of normal individuals and is nearly universal in patients with elevated right-sided pressures 1
• In patients with suspected pulmonary embolism or elevated right heart pressures, 87% will have detectable TR jets 1

2. Obtain the Peak TR Velocity

• Use continuous-wave Doppler aligned parallel to the direction of the TR jet 2
• Obtain the peak velocity (V) of the tricuspid regurgitant jet from the complete Doppler envelope 1
• The measurement requires a complete, well-defined spectral envelope to accurately identify peak velocity 2
• Normal physiologic TR typically shows peak systolic velocities between 1.7-2.3 m/s 1

3. Calculate the RV-RA Pressure Gradient

• Apply the simplified Bernoulli equation: ΔP = 4V² 1, 2
• This calculates the systolic pressure gradient between the right ventricle and right atrium 2
• For example, a TR velocity of 2.5 m/s corresponds to a gradient of 25 mmHg; 3.0 m/s corresponds to 36 mmHg 1

4. Estimate Right Atrial Pressure

Right atrial pressure can be estimated by three methods 1:

• Clinical examination of jugular venous pressure 1
• Inferior vena cava (IVC) assessment: measure IVC diameter and respiratory variation 1
  • IVC diameter <2.1 cm is considered normal 1
  • Assess respiratory collapse with sniff maneuver
• Direct measurement from central venous catheterization in critically ill patients 1

5. Calculate RV Systolic Pressure

• RV systolic pressure = Transtricuspid gradient (4V²) + estimated RA pressure 1, 2
• In the absence of pulmonary valve stenosis, RV systolic pressure equals pulmonary artery systolic pressure (PAsP) 1

Critical Clinical Context

Acute vs. Chronic Conditions

• In acute conditions (e.g., acute pulmonary embolism), the RV can only generate PAsP up to 60 mmHg acutely 1
• Expected TR jet velocities in acute PE are 2.5-3.5 m/s, corresponding to PAsP of 40-50 mmHg 1
• PAsP >60 mmHg suggests chronic process such as repeated pulmonary emboli or chronic pulmonary disease 1

Important Caveats

• The method may underestimate pressure when TR is very severe due to equalization of RV and RA pressures 1
• Measurements should be performed at end-expiration in patients with RV systolic dysfunction, as quiet respiration significantly affects TR velocity in these patients 3
• The technique requires adequate TR signal; if peak velocity cannot be recorded, alternative methods based on the timing of retrograde flow dynamics may be considered 4

Prognostic Implications

• In sickle cell disease, TR velocity ≥2.5 m/s identifies patients at increased mortality risk 1
• Mortality rates increase progressively: <2.5 m/s (2%), 2.5-2.9 m/s (10%), ≥3.0 m/s (20%) 1

Integration with Other RV Assessment Parameters

When measuring RV systolic pressure, comprehensive RV evaluation should include 1:

• RV dimensions and function (FAC, TAPSE, S' velocity) 1
• RA volume 1
• IVC diameter and respiratory variation 1
• Assessment for RV dysfunction and pressure overload 1