What's the next best test for a patient with progressive dyspnea, hypoxemia, and signs suggestive of pulmonary hypertension?

Next Best Test for Suspected Pulmonary Hypertension

For a 62-year-old woman with progressive dyspnea on exertion, reduced exercise tolerance, walk test with significant hypoxemia, dry crackles in bases, parasternal lift, and 1/4 systolic murmur, the next best test is a transthoracic echocardiography to confirm the diagnosis of suspected pulmonary hypertension.

Rationale for Echocardiography as First-Line Test

Transthoracic echocardiography is the recommended initial diagnostic test for patients with suspected pulmonary hypertension (PH) based on multiple guidelines:

• Echocardiography can simultaneously provide an estimate of right ventricular systolic pressure, assess functional and morphologic cardiac sequelae of PH, and identify possible cardiac causes of PH 1
• It has high sensitivity (79-100%) and specificity (68-98%) in detecting moderate PH 1
• The ESC/ERS guidelines specifically recommend echocardiography as the initial non-invasive diagnostic test when PH is suspected 1

Key Echocardiographic Findings to Look For

The echocardiogram should assess:

1. Tricuspid regurgitation velocity to estimate right ventricular systolic pressure
2. Right heart chamber enlargement (right atrium and ventricle)
3. Interventricular septal flattening (left ventricular eccentricity index >1.1)
4. Right ventricular function
5. Pulmonary artery diameter (>25 mm suggests PH)
6. Inferior vena cava diameter and collapsibility 1

Diagnostic Algorithm After Echocardiography

Based on the echocardiographic probability of PH, the following steps should be taken:

If High Probability for PH on Echo:

• Right heart catheterization (RHC) is recommended (Class I recommendation) 1
• This is particularly important for this patient with symptoms and signs suggestive of PH

If Intermediate Probability for PH on Echo:

• Further assessment including RHC should be considered (Class IIa recommendation) 1

If Low Probability for PH on Echo:

• Alternative diagnoses should be considered 1

Additional Testing After Echocardiography

After echocardiography confirms the suspicion of PH, the following tests should be performed to classify the type of PH:

1. Ventilation/perfusion (V/Q) lung scan - Class I recommendation to exclude chronic thromboembolic PH (CTEPH) 1

   • V/Q scan has higher sensitivity than CT pulmonary angiography for CTEPH 1

2. High-resolution CT - Should be considered in all patients with PH (Class IIa recommendation) 1

   • Helps identify interstitial lung disease, emphysema, or PVOD

3. Pulmonary function tests and arterial blood gases - To evaluate for underlying lung disease 1

4. Right heart catheterization - Definitive test for diagnosis and classification of PH 1

   • Measures mean pulmonary artery pressure, pulmonary vascular resistance, and pulmonary capillary wedge pressure
   • Allows vasoreactivity testing

Common Pitfalls to Avoid

1. Skipping echocardiography - Some clinicians might be tempted to proceed directly to CT or V/Q scan, but echocardiography provides crucial initial assessment of cardiac structure and function

2. Relying solely on echocardiography - While it's an excellent screening tool, echocardiography can underestimate high pulmonary vascular resistance 2

3. Missing right heart catheterization - This is ultimately required for definitive diagnosis and classification of PH 1

4. Overlooking V/Q scan - Essential for ruling out CTEPH, which requires different treatment approaches 1

The patient's clinical presentation with progressive dyspnea, hypoxemia on exertion, parasternal lift, and systolic murmur strongly suggests pulmonary hypertension, making echocardiography the most appropriate next step in diagnosis.