From the Guidelines
Pulmonary hypertension on echocardiogram is primarily measured by estimating the pulmonary artery systolic pressure (PASP) using the tricuspid regurgitation jet velocity, with a peak velocity of >2.8 m/s suggesting pulmonary hypertension, as recommended by the 2015 ESC/ERS guidelines 1. The PASP is calculated using the modified Bernoulli equation (4v²) plus the estimated right atrial pressure, where v is the peak velocity of the tricuspid regurgitation jet. Some key points to consider when measuring pulmonary hypertension on echocardiogram include:
- The estimation of systolic PAP is based on the peak tricuspid regurgitation velocity (TRV) taking into account right atrial pressure (RAP) as described by the simplified Bernoulli equation 1.
- Right atrial pressure (RAP) can be estimated by echocardiography based on the diameter and respiratory variation in diameter of the inferior vena cava (IVC) 1.
- The European Association of Cardiovascular Imaging (EACVI) recommends using the continuous wave Doppler measurement of peak TRV as the main variable for assigning the echocardiographic probability of PH, rather than using a fixed value of 5 or 10 mmHg for PA systolic pressure (PASP) estimations 1.
- Additional echocardiographic findings that support the diagnosis of pulmonary hypertension include right ventricular enlargement, right ventricular hypertrophy, flattening of the interventricular septum, dilated pulmonary arteries, and decreased right ventricular function 1.
- The pulmonary acceleration time (PAT) may also be measured, with values less than 100 ms suggesting elevated pulmonary pressures 1.
- Right ventricular systolic pressure can be estimated as well, which in the absence of pulmonary stenosis is equivalent to PASP 1.
- While echocardiography provides a good screening tool, it's essential to note that right heart catheterization remains the gold standard for definitive diagnosis, as echo can sometimes underestimate or overestimate pulmonary pressures by 10-20 mmHg compared to direct measurement 1.
From the Research
Measurement of Pulmonary Hypertension on Echocardiogram
Pulmonary hypertension is defined as a mean arterial pressure of ≥25 mmHg as confirmed on right heart catheterisation 2. The measurement of pulmonary hypertension on echocardiogram (echo) can be estimated using the simplified Bernoulli equation from the peak tricuspid regurgitant velocity and adding this to an estimate of right atrial pressure.
Estimation of Pulmonary Artery Pressure
- The pulmonary arterial systolic pressure has been estimated on echo by utilising the simplified Bernoulli equation from the peak tricuspid regurgitant velocity and adding this to an estimate of right atrial pressure 2.
- However, for an individual patient, significant overestimation and underestimation can occur, and the levels of agreement between the two is poor 2.
- Recent guidance has suggested that echocardiographic assessment of pulmonary hypertension should be limited to determining the probability of pulmonary hypertension being present rather than estimating the pulmonary artery pressure 2.
- Echocardiography can be used to estimate right ventricular systolic pressure noninvasively, and Doppler echocardiographic assessment of right ventricular pressure at the time of pulmonary valve opening can predict pulmonary artery diastolic pressure 3.
Echocardiographic Views
- No single echocardiographic view consistently yields the maximum velocity of tricuspid regurgitation, and all seven views must be used to be certain that the maximum velocity of tricuspid regurgitation has been obtained 4.
- The apical four-chamber view alone is inadequate for determining the maximum velocity of tricuspid regurgitation 4.