What imaging tests should be ordered to reassess heart space in a patient with a history of pectus excavatum?

Imaging Recommendations for Reassessing Heart Space in Pectus Excavatum

For reassessing heart space in patients with pectus excavatum, chest radiography and transthoracic echocardiography are the most appropriate initial imaging studies, followed by CT or MRI for more detailed evaluation if needed. 1

Initial Imaging Evaluation

• Chest radiography (PA and lateral views) should be the first imaging study performed as it provides basic assessment of cardiac size, position, and pulmonary vasculature patterns 1
• Transthoracic echocardiography (TTE) should be performed concurrently with chest radiography to assess cardiac function, structure, and any compression effects 1, 2
• TTE specifically evaluates:
  • Cardiac chamber dimensions and function
  • Presence of mitral valve prolapse (occurs in approximately 15% of pectus excavatum patients)
  • Right ventricular compression or displacement
  • Potential pericardial effusion (found in up to 33% of patients with severe pectus excavatum) 2, 3

Advanced Imaging Options

Computed Tomography (CT)

• CT chest without IV contrast is indicated for:
  • Calculating the Haller index (pectus severity index) - surgery typically considered when index >3.25
  • Evaluating the extent of sternal depression and cardiac compression
  • Assessing anatomical relationships between the sternum and heart 2, 4
• Limited CT technique focused on obtaining the Haller index is preferred over full chest CT to minimize radiation exposure 4

Magnetic Resonance Imaging (MRI)

• Cardiac MRI without and with IV contrast is recommended when:
  • More detailed assessment of cardiac function is needed
  • TTE images are suboptimal due to chest wall deformity
  • Evaluation of interventricular dependence is required 1, 5
• MRI provides superior assessment of:
  • Right ventricular volume and function
  • Cardiac displacement
  • Interventricular septal motion during respiration
  • Pericardial effusion 5, 3

Clinical Considerations and Pitfalls

• Standard echocardiographic windows may be limited in patients with severe pectus excavatum due to cardiac displacement 6, 3
• Cardiac displacement to the left occurs in approximately 50% of patients with significant pectus excavatum 3
• Right ventricular wall motion abnormalities are common (28-44%) and should not be mistaken for primary cardiac pathology 3
• Pericardial effusion is more common in patients with higher pectus severity indices 5
• Stress imaging tests are generally not indicated unless there are specific concerns about coronary artery disease 1
• Cardiac catheterization is unnecessary for diagnosis and should be reserved only for interventional procedures 1

Recommended Imaging Algorithm

1. Start with chest radiography and transthoracic echocardiography 1
2. If initial imaging is inadequate or more detailed assessment is needed:
   • For anatomical evaluation: Limited chest CT to calculate Haller index 4
   • For functional evaluation: Cardiac MRI without and with contrast 1, 5
3. Reserve specialized imaging techniques (TEE, stress imaging) for specific clinical scenarios where standard imaging is insufficient 1