Estimating Pulmonary artery pressure
PA systolic pressure : TR jet + 10 mmhg
PA diastolic pressure : PR end diastolic jet + 10
PA mean pressure : Peak PR gradient
Other complex methods to arrive ar PAP in the absence of TR or PR
The Dabestani -Mahan ‘s equation* – The mean PA pressure = 90 – (0.62 X acceleration time).
It is popular for calculating PAP by measuring pulmonary artery Doppler acceleration time .
Many believe it is neither sensitive nor practical in real clinical setting.
*Even though Dabestani is the first author of this paper Mahan got the full credits for the simple reason his name is easily remembered !
Note the peak TR jet is around 50mmhg and predicted RVSP would be 60mmhg.One would have expected still higher RV pressure but since the RV is dysfunctional the true PAP may be underestimated.
The classical D shaped IVS during systole . D shape indicates RV pressure during systole is almost equal or even higher than LV. ( Please recall D shape occurs in Volume overload also but the timing is in diastole !)
Pulmonary valve M-Mode
According to Wyeman the following M mode signs are useful in diagnosing PAH.
Currently , one may consider M-Mode echo to be an obsolete , but still the foundations help us understand the hemo-dynamics.
Normally atrial contraction produce an inward movement* on the closing pulmonary leaflet . This happens because the MPA end diastolic pressure is usually lower than right atrial a wave .In severe PAH the elevated pulmonary diastolic pressure does not allow the atrial contraction to intend the pulmonary leaflet in pre-systolic atrial contraction .Hence pulmonary valve a wave in m -mode is diminished or even absent .
In PAH even premature closure of pulmonary valve may occur resulting in mid systolic notch .This is referred to as flying “W” -Mid systolic notch. (See below)
* The motion we see in short axis M-Mode is that of left pulmonary cusp that moves posteriorly.
Image source : Karmarkar SG. Pulmonary valve echocardiography. J Postgrad Med 1979;25:219-23
Absence of a dip is a hemo-dyanmicaly important sign pf PAH but with one important caveat .This absence of a dip is valid only until RV failure occur.In th presence of elevated RVEDP a begin to appear again
hypertension by a pulsed Doppler technique. Circulation. 1983; 68(2): 302-9. 5.Stevenson JG. et al, Comparison of several noninvasive methods for estimation of pulmonary artery pressure. J Am
Soc Echocardiogr. 1989; 2: 157-71. 6.Yock PG, Popp RL. Noninvasive estimation of right ventricular systolic pressure by Doppler ultrasound in patient with tricuspid regurgitation. Circulation 1984; 70:657-62.