- TOE better than TTE
- Normal pulmonary arterial pressure in a person living at sea level has a mean value of 12-16 mm Hg.
- Pulmonary hypertension is present when mean pulmonary artery pressure exceeds 25 mm Hg at rest or 30 mm Hg with exercise.
MEASUREMENT OF PULMONARY ARTERY PRESSURE
- Doppler Echo can approximate pulmonary artery systolic pressure (PASP) using
— tricuspid valve velocity (4v2 = TV pressure gradient)
— estimated CVP (=RA pressure)
— Bernoulli equation
PASP = RVSP (in the absence of RVOTO or pulmonic stenosis)
RVSP = 4v2 + CVP
Mean PAP can be approximated because mPAP = 0.61•sPAP + 2.
- A systolic PAP of 40 mm Hg typically implies a mean PAP more than 25 mm Hg = pulmonary hypertension
Severity of pulmonary hypertension (mPAP)
Mild = 25-40mmHg
Moderate = 41-55mmHg
Severe = > 55mmHg
The mean and end diastolic pressures in the pulmonary artery are directly assessed by measuring peak and end-diastolic velocities of the pulmonary regurgitant jet
- Diastolic PA pressure (dPAP) = PR end diastolic pressure gradient + RA pressure
- Mean PA pressure (mPAP) = PR peak pressure gradient + RA pressure
Mean pulmonary arterial pressure can also be calculated from the acceleration time of the RVOT VTI.
OTHER ECHOCARGRAPHIC FINDINGS
- dilated PA
— greater calibre than aorta
- RA dilation
— RV to LV ratio > 0.6 in the four chamber view
- bulging of septum into the LV cavity causing diastolic dysfunction
- presence of at least a trivial tricuspid regurgitant jet is almost universal – increases with severity of pulmonary hypertension
Cause may be identified:
- LV failure
- mitral or aortic valve disease