What is the next step in the workup for Pulmonary Arterial Hypertension (PAH) when an echocardiogram shows an elevated Right Ventricular Systolic Pressure (RVSP)?

Workup for Pulmonary Arterial Hypertension with RVSP 96mmHg

Right heart catheterization is definitively indicated as the next step in the workup for a patient with suspected pulmonary arterial hypertension (PAH) when echocardiography shows an elevated right ventricular systolic pressure (RVSP) of 96mmHg. 1

Diagnostic Approach

Initial Echocardiographic Findings

• An RVSP of 96mmHg on echocardiography strongly suggests severe pulmonary hypertension, as normal RVSP is typically around 21±4 mmHg with an upper limit of approximately 30 mmHg 1
• While echocardiography is an excellent screening tool for PAH, it may be imprecise in determining actual pressures compared to invasive evaluation 1
• Echocardiographic findings should be evaluated for associated abnormalities such as right atrial enlargement, right ventricular enlargement, and pericardial effusion 1

Right Heart Catheterization

• Right heart catheterization is the gold standard for confirming the diagnosis of PAH and is required before initiating treatment 2, 3

• Cardiac catheterization with contrast angiography provides definitive information regarding:

  • Pulmonary artery pressure measurements
  • Pulmonary capillary wedge pressure (to rule out left heart disease)
  • Pulmonary vascular resistance calculation
  • Cardiac output assessment
  • Pulmonary vasoreactivity testing 1

• Vasoreactivity testing should be performed during catheterization using inhaled nitric oxide, intravenous adenosine, or epoprostenol 3

• A positive vasoreactivity test (reduction of 10 mmHg in mean pulmonary arterial pressure or achieving a mean pulmonary artery pressure <40 mmHg, with no change or an increase in cardiac output) identifies the approximately 10% of PAH patients who may respond to calcium channel blockers 3

Additional Diagnostic Workup

• Comprehensive evaluation should include:
  • Pulmonary function tests to assess for underlying lung disease 1
  • Six-minute walk test to establish functional capacity baseline 1
  • Non-contrast CT scan of the chest or CT angiogram if thromboembolic disease is suspected 1
  • Ventilation/perfusion (V/Q) scan to evaluate for chronic thromboembolic pulmonary hypertension 1
  • Screening for sleep apnea 1
  • Echocardiography with bubble study if there is suspicion of intracardiac shunts 1

Differential Diagnosis to Consider

• With such a high RVSP (96mmHg), a thorough search for underlying causes is essential, including:
  • Collagen vascular disease
  • Portal hypertension
  • HIV infection
  • History of anorexigen use
  • Pulmonary veno-occlusive disease
  • Sleep apnea
  • Chronic obstructive pulmonary disease
  • Sarcoidosis 1
  • Congenital heart disease with systemic-to-pulmonary shunts 1

Clinical Pearls and Pitfalls

• Doppler echocardiography may underestimate RVSP in patients with severe PAH, so even with an already high value of 96mmHg, the actual pressure could be higher 1
• Right ventricular function is a critical determinant of outcomes in PAH, and should be carefully assessed during the diagnostic workup 4
• Elevated RVSP on echocardiography correlates with poor outcomes - the mortality risk increases by approximately 40% with every 10 mmHg increase in PA systolic pressure 1
• Pressure-volume loop shape and RV systolic pressure differential during catheterization can provide additional information about PAH severity and RV-arterial coupling 5
• In patients with congenital heart disease, Doppler echocardiography has shown good correlation with catheterization measurements (r = 0.853), but confirmation with catheterization remains essential 6

Remember that while echocardiography is an excellent screening tool, right heart catheterization remains the definitive diagnostic test for PAH and is essential for guiding appropriate therapy decisions and assessing prognosis 1, 2.