How to Proceed in a Multimodality Analysis for the Diagnosis and Risk Stratification of Pulmonary Hypertension?

Transthoracic echocardiography

TTE is considered a highly useful, inexpensive, safe, and available imaging modality for initial approach to differential diagnosis of PH. Although a normal TTE does not rule out diagonsis, it decreases the likelihood of PH. Neither CT nor CMRI are part of the initial line of PH; however, in selected patients they can provide additional information before proceeding to right heart catheterization. ^,

It is important to be familiar with normal ranges of RV size and function. ^, TTE showing right heart structure and function abnormalities increases suspicion of PH. It also allows detection of left heart (systolic and diastolic dysfunction, valvular heart disease) and congenital heart disease as potential causes of PH. RV function surrogates such as RV fractional area change, right atrial size, pericardial effusion, tricuspid annular plane systolic excursion (TAPSE), systolic pulmonary artery pressure (SPAP)/TAPSE ratio, and eccentricity index are recommended in follow-up and assessment of therapy response. However, it is important to note that these surrogates should be interpreted in the context of other clinical and imaging parameters, as they are not standalone diagnostic tools. Doppler can be used to estimate the possibility of PH by measuring tricuspid regurgitant jet velocity (TR) and calculating SPAP using the modified Bernoulli equation. When no TR is present or the signal is inadequate, pulmonary acceleration time can be used to calculate mPAP obtained from pulse wave Doppler signal of pulmonary flow. Pulmonary artery diastolic pressure can be estimated if pulmonary regurgitation is present. The velocity at end-diastole is converted into a pressure gradient, adding the estimated right atrial pressure to the resulting value. Finally, both left ventricle and RV output can be calculated. In clinical practice, differentiating acute, chronic, and chronic acute PH can be challenging ( ).

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