In patients with severe pulmonary arterial hypertension and lef to right cardiac shunt the below noted regression equation showed good correlation with cath based studies: PVR(WU) = 31.87(TRV/RVOT VTI) + 2.7 [Ajami et al.]

But a uniform formula irrespective of level of pulmonary pressure/resistance is sill in search. I feel, there are plenty of scope for the researchers in this regard.

Good topic for discussion; other recent proposed echo estimates of PVR with their Sensitivity and NPV (negative predictive values) are as follows:

i) PVR = PAMP (echo) - PCWP/CO (echo), where PAMP (echo) is calculated

as PASP (echo) × 0.61 + 2 mmHg, according to Chemla et al., with PASP (echo) = peak trans-tricuspid retrograde pressure drop + 10 or 7 mmHg (two proposed/assumed values for RAP). Pulmonary capillary wedge pressure of 10 mmHg is also assumed.

Sensitivity and NPV: 100%,100%.

ii) PVR = PAMP - PCWP/CO (echo) where PAMP is derived from PADP as PADP+0.33 (PASP-PAPD) and PADP was calculated as 4 × (trans-tricuspid pressure drop at the time of pulmonary valve opening)2 + estimated RAP of 10 mmHg.

Sensitivity and NPV: 100%,100%.

iii) The ratio of trans-tricuspid peak pressure drop/RV outflow tract velocity time integral

Sensitivity and NPV: 88%, 75%.

iv) PASP/(HR × RVOT velocity time integral)

Sensitivity and NPV: 94%, 88%.

Note: The SI unit of PVR is still Dyne. sec. cm -5 (and not dynes cm/s2)

Kind regards

AC

Thanks a lot Dr. Chowdhury. If u can provide the referrences, it'll be even more helpful.

Regards

Truly informative.

Thanks Arindam sir.