What labs should be drawn for a patient with pectus carinatum (pectus carinatum) and suspected connective tissue disorder, such as Marfan syndrome (Marfan syndrome)?

Laboratory Tests for Patients with Pectus Carinatum and Suspected Marfan Syndrome

Patients with pectus carinatum and suspected Marfan syndrome should undergo comprehensive cardiovascular imaging with echocardiography as the primary diagnostic test, followed by genetic testing for FBN1 mutations and a complete connective tissue disorder workup. 1

Initial Laboratory and Diagnostic Evaluation

Cardiovascular Assessment

• Echocardiogram (TTE): Essential first-line test to evaluate:

  • Aortic root diameter (sinuses of Valsalva)
  • Ascending aorta dimensions
  • Mitral valve for prolapse and regurgitation
  • Aortic valve function
  • Left ventricular function 1, 2

• Advanced Cardiovascular Imaging:

  • CT or MRI of the thoracic aorta if echocardiogram findings are abnormal or inadequate
  • Complete imaging of the entire aorta to establish baseline measurements 1, 2

Genetic Testing

• FBN1 gene sequencing: Primary genetic test for Marfan syndrome 1
• TGFBR1 and TGFBR2 gene sequencing: If FBN1 is negative but clinical suspicion remains high 1

Ocular Assessment

• Dilated eye examination: To evaluate for ectopia lentis (lens dislocation), which is highly specific for Marfan syndrome 1, 2

Skeletal Assessment

• Spine radiographs: To evaluate for scoliosis, which commonly co-occurs with pectus deformities in Marfan syndrome 1, 2
• Bone density assessment: If indicated based on clinical findings 2

Additional Testing Based on Initial Findings

If Aortic Abnormalities Are Detected

• Comprehensive aortic imaging: MRI or CT angiography from cerebrovascular circulation to pelvis 1
• Serial echocardiograms: Frequency based on aortic root size:
  • Normal: Every 2-3 years
  • <4.5 cm with growth rate <0.5 cm/year: Annually

  • 4.5 cm or growth rate >0.5 cm/year: Every 6 months 1, 2

If Mitral Valve Abnormalities Are Suspected

• Transesophageal echocardiography: For detailed assessment of mitral valve prolapse and mitral annular disjunction, which are more common in patients with pectus deformities and Marfan syndrome 3

Clinical Relevance and Interpretation

The incidence of Marfan syndrome in patients with pectus deformities is approximately 5.3%, significantly higher than the 0.3% in the general population 4. Cardiac anomalies show an overall incidence of 35% in patients with pectus deformities, with 84% of those diagnosed with Marfan syndrome having cardiac abnormalities 4.

Recent research indicates that patients with pectus excavatum and Marfan syndrome have higher frequency of mitral valve abnormalities, increased right ventricular volumes, and lower right ventricular ejection fraction compared to those without pectus deformities 3. This suggests that pectus deformities in Marfan syndrome may indicate more severe disease expression.

Important Considerations

• Pectus carinatum can be part of familial thoracic aortic aneurysm syndromes, even without other obvious Marfan features 1, 5
• Cardiovascular assessment should always take precedence over pectus repair considerations 2
• Patients with combined type pectus deformity (both excavatum and carinatum features) have the highest incidence of Marfan syndrome (20%) 4
• Monitoring should continue even after any surgical interventions, as some features of Marfan syndrome are age-dependent 2

Pitfalls to Avoid

• Don't rely solely on physical examination: Many cardiovascular manifestations of Marfan syndrome are asymptomatic until complications occur 6
• Don't dismiss isolated pectus carinatum: Even without other obvious features, it may be the first manifestation of an underlying connective tissue disorder 5
• Don't forget family screening: First-degree relatives should undergo echocardiography and clinical evaluation if Marfan syndrome is confirmed 2
• Don't delay cardiac monitoring: Aortic complications are the leading cause of morbidity and mortality in Marfan syndrome 1

By following this comprehensive laboratory and imaging approach, clinicians can effectively evaluate patients with pectus carinatum for Marfan syndrome and other connective tissue disorders, potentially preventing life-threatening complications through early detection and management.