Congenital Diaphragmatic Hernia

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Congenital Diaphragmatic Hernia
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Congenital Diaphragmatic Hernia

• What is Congenital Diaphragmatic Hernia?
• Congenital Diaphragmatic Hernia is when part of
  the stomach and the intestine herniate through a
  posterolateral defect in the diaphragm.

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Congenital Diaphragmatic Hernia Characteristics
and Facts

• CDH occurs in approximately 1 out of every 2,500
  live births.
• The encroachment of the abdominal viscera alters
  lung growth and maturation.
• Hypoxemia and persistent pulmonary hypertension
  are the primary causes of high morbidity and
  mortality associated with CDH.

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Diaphragm Development And Its Role In CDH

• The anomaly underlying CDH is failure of normal
  diaphragm development during embryogenesis.
• Efforts for improving survival have been
  frustrating due to a lack of understanding of the
  cause of the diaphragmatic defect.
• 5 theories regarding the contributing mechanisms
  have been derived.

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CDH Theory 1

• Malformation of the diaphragm is linked to
  abnormal development of the adjacent lung.

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CDH Theory 2

• Malformation of the diaphragm is the result of
  abnormal muscle innervation by the phrenic nerve.

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CDH Theory 3

• Improper myotube formation causes CDH.
• Myotubes are multinucleate structures that are
  formed by the fusion of proliferating myoblasts.

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CDH Theory 4

• CDH forms as a result of failure of the
  pleuroperitoneal canals to close.
• Pleuroperitoneal canals are narrow channels
  connecting pleural and peritoneal cavities.
• Currently this is the most popular theory.

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CDH Theory 5

• The defect in the diaphragm seen in CDH results
  from failure of the pleuroperitoneal fold to form
  properly.

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Lung Growth and Development

• The high mortality rate from CDH is caused in
  part by pulmonary hypoplasia (PH) and immaturity
  of the lung.
• Many mechanisms have been studied that may lead
  to PH.

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Mechanisms in Lung Growth and Development and CDH

• The role of transcription factors
• A host of growth factors
• Retinoic acid and antioxidants
• Effect of pressure on fetal lung growth
• Prenatal glucocorticoids

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Pulmonary Vasculature

• Before birth the placenta serves as the organ for
  gas exchange.
• At birth, the lung must rapidly assume the role
  of gas exchange.
• At present the mediators that contribute to the
  immediate postnatal decrease in pulmonary
  vascular resistance are poorly understood.
• Failure of this process causes persistent
  pulmonary hypertension of the newborn (PPHN).

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Conclusion

• An extensive amount of investigation has been
  done in order to explain the origins of CDH and
  associated PH and hypertension.
• Unfortunately our understanding of the
  pathophysiology of the disease is still
  incomplete.
• Hopefully with ongoing CDH research the prognosis
  of CDH babies will be significantly improved.

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References

• Groshe, J., Islam, S., Boulanger, S. (2005).
  Congenital diaphragmatic hernia searching for
  answers. The American Journal of Surgery. Vol.
  190, pg. 324-332.
• Moore, K., Dalley, A. (2005) Clinically
  Oriented Anatomy. Lippincott Williams Wilkins,
  Maryland, pp. 252.
• Tannuri, U. (2001). Heart hypoplasia in an
  animal model of congenital diaphragmatic hernia.
  Revista do Hospital das Clinicas. Vol. 56, no. 6.