Initial Diagnostic Step for Pulmonary Artery Pressure Measurement
In patients with suspected pulmonary hypertension, Doppler echocardiography should be performed immediately as the first-line noninvasive screening test to estimate pulmonary artery pressure and assess right ventricular function. 1, 2
Primary Screening Approach
Doppler echocardiography serves as the initial diagnostic step because it is noninvasive, widely available, and can detect pulmonary hypertension while providing crucial structural and functional cardiac information. 1 This recommendation carries a Grade A strength based on substantial benefit, despite fair quality evidence acknowledging that echocardiography may be imprecise in determining actual pressures compared to invasive evaluation in some patients. 1
Key Echocardiographic Parameters to Assess
The echocardiographic evaluation must include:
Tricuspid regurgitation velocity (TRV) to estimate right ventricular systolic pressure, with PH considered likely when TRV exceeds 3.4 m/s (corresponding to PA systolic pressure >50 mmHg). 1, 3
Right ventricular size and function, including assessment for right ventricular enlargement, right atrial enlargement, and pericardial effusion. 1, 2
Additional echocardiographic signs from at least two different categories: ventricular parameters (RV/LV basal diameter ratio >1.0, interventricular septal flattening), pulmonary artery parameters (RVOT acceleration time <105 msec, PA diameter >25 mm), and right atrial/IVC parameters (IVC diameter >21 mm with decreased collapse, right atrial area >18 cm²). 1, 3
Left ventricular systolic and diastolic function to identify Group 2 pulmonary hypertension from left heart disease, including assessment for left atrial enlargement and valvular abnormalities. 1, 2
Contrast echocardiography (agitated saline) to detect intracardiac shunting when congenital heart disease is suspected. 1, 2
Critical Limitations and Pitfalls
Do not rely solely on echocardiography for definitive diagnosis. 4, 5 A meta-analysis demonstrated that echocardiography has a sensitivity of only 83% and specificity of 72% for diagnosing pulmonary hypertension, with a correlation coefficient of 0.70 between echo-estimated and catheter-measured pressures. 5 Echocardiography may significantly underestimate systolic PAP in patients with severe tricuspid regurgitation and can overestimate pressures in populations with mostly normal pressures. 1, 3
A "low probability" echocardiogram does not exclude pulmonary hypertension, particularly in patients with risk factors such as connective tissue diseases, congenital heart disease, portal hypertension, HIV infection, or history of thromboembolic disease. 3
Mandatory Confirmatory Testing
Right heart catheterization is required in all patients with suspected pulmonary hypertension to confirm the diagnosis, establish specific hemodynamic classification (measuring mean PAP >20 mmHg, pulmonary artery wedge pressure, cardiac output, and pulmonary vascular resistance), determine severity, and guide therapy. 1, 2 Although cardiac catheterization rarely reveals unsuspected findings in the current era due to advances in noninvasive imaging, it remains the only definitive diagnostic method and is essential before initiating targeted therapies. 1
Avoid using exercise Doppler echocardiography for PH screening due to lack of validated criteria and uncertain clinical value. 1, 3
Algorithmic Approach Based on Echocardiographic Probability
For symptomatic patients, management proceeds based on echocardiographic probability:
High probability (TRV >3.4 m/s with additional signs): Proceed directly to right heart catheterization and complete diagnostic workup. 1, 2, 3
Intermediate probability (TRV 2.9-3.4 m/s or presence of risk factors): Consider right heart catheterization if risk factors or associated conditions are present; otherwise, perform echocardiographic follow-up. 1, 3
Low probability (TRV ≤2.8 m/s without additional signs): Consider alternative diagnoses, but maintain echocardiographic follow-up if risk factors persist, as PH cannot be definitively excluded. 1, 3