Can pectus excavatum lead to shortness of breath (SOB) that resembles exercise-induced asthma?

Pectus Excavatum Can Cause Shortness of Breath That Mimics Exercise-Induced Asthma

Yes, pectus excavatum can cause shortness of breath during exercise that resembles exercise-induced asthma, and it should be specifically considered in the differential diagnosis when evaluating exercise-related respiratory symptoms. 1

Mechanism and Clinical Presentation

Pectus excavatum is a depression of the sternum and costal cartilages that can affect respiratory function through several mechanisms:

• Restrictive physiology: The chest wall deformity can limit full chest expansion during exercise 2
• Cardiac compression: The depressed sternum may compress or displace the heart, particularly affecting right ventricular volume 2
• Increased work of breathing: Patients may experience increased oxygen cost of breathing during exertion 3

The symptoms commonly include:

• Shortness of breath with exercise
• Decreased exercise endurance
• Chest pain or discomfort
• Rapid fatigue during physical activity

Differential Diagnosis from Exercise-Induced Asthma

When evaluating a patient with exercise-related shortness of breath, several key factors help distinguish pectus excavatum from exercise-induced bronchoconstriction (EIB):

1. Response to bronchodilators: Symptoms from pectus excavatum will not improve with bronchodilator therapy, unlike true EIB 1

2. Pulmonary function testing:

   • EIB shows ≥10% fall in FEV₁ after exercise challenge 4
   • Pectus excavatum may show restrictive pattern or normal spirometry 5

3. Physical examination:

   • Visible chest wall depression
   • Paradoxical chest wall movement during respiration in severe cases 1

4. Imaging:

   • CT scan with pectus index >3.25 suggests significant deformity 2

Diagnostic Approach

For patients presenting with exercise-related shortness of breath and suspected chest wall deformity:

1. Perform spirometry and detailed pulmonary examination to determine if symptoms are associated with restrictive lung conditions like pectus excavatum rather than EIB 1

2. Consider cardiopulmonary exercise testing to differentiate between EIB and other causes of exercise-induced dyspnea 1

3. Imaging evaluation:

   • Chest radiography to demonstrate depth of depression
   • CT scan to quantify severity (pectus index)
   • Echocardiography to assess for cardiac compression or mitral valve prolapse (present in ~15% of cases) 2

Management Considerations

The approach to management depends on severity and impact on quality of life:

• Mild cases with minimal symptoms: Reassurance and exercise programs to improve posture and cardiopulmonary fitness

• Moderate to severe cases with significant symptoms: Consider surgical evaluation when there are:

  • Severe, symptomatic deformity
  • Progressive worsening
  • Documented cardiac compression/displacement
  • Pulmonary function tests showing restrictive disease
  • CT scan with pectus index >3.25 2

Common Pitfalls

1. Misdiagnosis as asthma: Patients may be incorrectly treated with asthma medications for years without improvement 1

2. Underestimating psychological impact: The cosmetic deformity can cause significant psychological distress beyond the physiological effects

3. Assuming all cases are purely cosmetic: While some patients with pectus excavatum have normal pulmonary function and exercise capacity 5, others experience genuine physiological limitations that warrant intervention

4. Failing to consider other causes: Exercise-induced laryngeal dysfunction, cardiac conditions, and exercise-induced hyperventilation should also be considered in the differential diagnosis 1, 4

By recognizing pectus excavatum as a potential cause of exercise-related shortness of breath, clinicians can avoid misdiagnosis as exercise-induced asthma and provide appropriate management for affected patients.