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5 minutes crash course in cardiology : Echocardiogram in Pulmonary arterial hypertension

Posted in Cardiology - Clinical, Echo library and gallery, echocardiography, pulmonary hypertension, tagged a dip in pulmonary valve, berger equation, d sahped ivs in pah, echocardiogram in pah, flying w sign, m mode in pulmoanry, mahan equation, mid ssytolic notch in pulmonary, pa ssytolic pressure, preamture pulmonary valve closure, priamry pulmoanry hypertension, pulmonary acceleration time, pulmonary valve m mode echo, The Dabestani Mahan equation, tr jet pap on April 13, 2012| 1 Comment »

Echocardiogram in pulmonary HT has many aims .

Identify the etiology
Assess the effects of PAH on the right heart
Estimate the severity of PAH.
Possibly prognosticate

Echo helps us to confirm the valvular, myocardial or congenital heart diseases in the evaluation of PAH. Apart from these etiological diagnosis of PAH predominantly lies in a systematic medical work up .(Read Dana Point classification )

2-D features

RA RV dilates
RVH*may occur (Dilation is more common )
IVS assumes a D shape ( RV pressure is close to or even > than LV pressure )
Tricuspid annulus dilates

* For some reason RVH does not occur commonly in pulmonary hypertension , while LV hypertrophies promptly in systemic hypertension .

Doppler

Tricuspid valve begins to leak and RV ejects with giant “cv” waves into RA/JVP

Other Echo findings

MPA may dilate
Pulmonary regurgitation

At what pressure RV begins to dilate in PAH ?

It is not known .It is highly variable . But most will dilate their RV at a systolic pressure > 50mmg.

It is also possible the onset of TR and the magnitude of TR has a major say in the timing of RV enlargement .

We know RV is more sensitive to volume overload than pressure overload .

Paradoxically , it is often observed acute elevation in RV pressure dilate the RV faster than chronic ones.

Right atrium and right ventricle are significantly

The tricuspid annulus is dilated .Note the severe TR with twin jet morphology.

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.

Presence or absence and the amplitude of the “a” wave
magnitude of the e-f slope
presence of mid-systolic closure or notching
fluttering of the posterior pulmonic leaflet

Currently , one may consider M-Mode echo to be an obsolete , but still the foundations help us understand the hemo-dynamics.

The most important principle in the motion of pulmonary valve , is the relationship between pulmonary “a” wave and right atrial “a” wave

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

Reference