Understanding Pectus Excavatum: Comprehensive Guide to Diagnosis, Pathophysiology, and Modern Surgical Repair

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 https://doi.org/10.1016/j.athoracsur.2014.08.026

Pectus excavatum, commonly referred to as funnel chest or sunken chest, is the most prevalent congenital chest wall deformity. Characterized by a concave depression of the sternum and adjacent costal cartilages, this condition can range from a minor cosmetic concern to a severe physiological impairment affecting cardiopulmonary function. In this comprehensive column, we explore the intricate details of Pectus excavatum diagnosis, its underlying pathophysiology, and the revolutionary Nuss procedure that has redefined surgical outcomes.

Pathophysiology and Epidemiology

The exact pathophysiology of Pectus excavatum involves the overgrowth of the costal cartilages, which displaces the sternum posteriorly. While the precise etiology remains under investigation, it is widely considered a multifactorial condition involving genetic predisposition and connective tissue abnormalities, such as those seen in Marfan syndrome.

Epidemiology data indicate that Pectus excavatum occurs in approximately 1 in 300 to 400 live births, with a notable male predominance (ratio of 3:1 or 4:1). The deformity is often present at birth but becomes significantly more pronounced during the rapid growth spurts of adolescence.

Clinical Presentation

Patients with Pectus excavatum may present with a variety of symptoms depending on the severity of the sternal depression.

  • Physical Appearance: A visible hollow or "funnel" in the anterior chest wall.
  • Respiratory Symptoms: Shortness of breath (dyspnea), particularly during physical exertion.
  • Cardiac Symptoms: Chest pain, heart murmurs, or palpitations due to the heart being compressed or displaced.
  • Systemic Effects: Easy fatigability and poor posture (kyphosis).

Imaging Features and Diagnostic Workup

Accurate diagnosis relies on a combination of physical examination and advanced imaging.

1. Radiographic Evaluation

Standard chest X-rays are the first line of imaging.

  • Chest P-A: Often shows a blurring of the right heart border and displacement of the heart (mediastinum) to the left.
  • Lateral View: Clearly demonstrates the depth of the sternal depression.

 


 [Figure 1] Chest P-A: Findings show blurring of the right heart border and a leftward displacement of the mediastinal silhouette.

 


[Figure 2] Chest Lt. lateral (Image B): Lateral chest radiograph. Notable depression of the anterior sternum (arrow) is visible.

2. Computed Tomography (CT) and the Haller Index

CT scanning is the gold standard for quantifying the severity of the deformity. The Haller Index (or chest wall index) is calculated by dividing the transverse diameter of the chest by the narrowest anteroposterior diameter.

  • Normal Index: 2.0 to 3.0.
  • Severe Pectus Excavatum: Index > 3.25.

 

[Figure 3] Axial CT (Image C): Computed tomography of the chest. It shows the heart being compressed or displaced to the left due to the depression of the sternum, with a chest wall index (Haller Index) measured at 3.25 or higher.

Differential Diagnosis

When evaluating a sunken chest, clinicians must rule out:

  1. Achondroplasia: Short-limbed dwarfism with distinct skeletal features.
  2. Ankylosing Spondylitis: Inflammatory arthritis affecting the spine, though it may cause secondary chest constraints.
  3. Osteogenesis Imperfecta: "Brittle bone disease" which can lead to various thoracic deformities.
  4. Pneumothorax: Acute collapse of the lung, which presents with sudden pain and respiratory distress rather than chronic structural deformity.

Treatment Options: From Conservative to Surgical

Treatment is determined by the severity and the presence of physiological symptoms.

Non-Surgical Approaches

For mild cases, physical therapy focusing on posture and chest wall strength, or vacuum bell therapy to gradually lift the sternum, may be considered.

Surgical Correction: The Nuss and Ravitch Procedures

  • Nuss Procedure (MIRPE): A minimally invasive technique where a curved metal "Nuss bar" is inserted under the sternum to "pop" it into a normal position.
  • Ravitch Procedure: A traditional open surgery involving the resection of abnormal costal cartilage and repositioning of the sternum.

 

[Figure 5] Nuss bar: A curved metal bar made of stainless steel used for the correction of pectus excavatum.

Innovation in Bar Stabilization

One of the greatest challenges in the Nuss procedure is "bar displacement". Recent advancements have introduced new stabilization devices to ensure a 0% displacement rate.

[Figure 6] Repair using shape-customized bar molding technology: (A) Eccentric asymmetric repair using an asymmetric bar. (B) Unbalanced asymmetric repair using a seagull-shaped bar. (C) Bar molding method based on terrain contour matching to the patient's chest wall.

To prevent the bar from flipping, modern surgeons use Claw Fixators and Hinge Plates.

 


[Figure 7] Claw Fixator: It secures the bar by gripping the ribs in a hook-like manner without sutures to prevent bar flipping.

 

[Figure 8] Hinge Plate: (A) It prevents muscle stripping by reinforcing the entry point into the pleural cavity. (B) Hinge plate and claw fixator as shown on a chest radiograph.

Earlier methods utilized simpler stabilizers or multi-point pericostal sutures.

 


[Figure 9] Traditional Stabilizer: A method where the device is installed at the end of the bar and secured to the adjacent ribs using pericostal sutures.

 

[Figure 10] Multi-point pericostal suture fixation technique: The bar is secured at multiple points to prevent migration.

Quiz

Question 1: A 16-year-old male presents for evaluation of a congenital chest deformity. Physical exam shows significant sternal depression. A CT scan reveals a Haller Index of 3.4. Which of the following is the most likely diagnosis?

A) Achondroplasia

B) Ankylosing spondylitis

C) Pectus excavatum

D) Pneumothorax

Answer: C) Pectus excavatum. Explanation: A Haller Index > 3.25 is diagnostic of severe Pectus excavatum.

Question 2: During a Nuss procedure for Pectus excavatum repair, which device is specifically designed to be anchored to the ribs using a "hook" mechanism to prevent bar displacement without requiring sutures?

A) Traditional Stabilizer

B) Hinge Plate

C) Claw Fixator

D) Pericostal Suture

Answer: C) Claw Fixator. Explanation: The Claw Fixator uses blades/hooks to grip the ribs and secure the bar end without sutures.

Question 3: A patient undergoes a Chest P-A radiograph for chest wall evaluation. The results show a blurred right heart border and a leftward displacement of the mediastinum. These findings are most characteristic of which condition?

A) Pectus carinatum

B) Pectus excavatum

C) Scoliosis

D) Pleural effusion

Answer: B) Pectus excavatum. Explanation: In Pectus excavatum, the sunken sternum compresses the heart, often blurring the right heart border and pushing the heart into the left hemithorax.

References

[1] D. Nuss, "A 10-year review of a minimally invasive technique for the correction of pectus excavatum," J. Pediatr. Surg., vol. 33, no. 4, pp. 545-552, 1998.

[2] H. J. Park et al., "A next-generation pectus excavatum repair technique: new devices make a difference," Ann. Thorac. Surg., vol. 99, no. 2, pp. 455-461, 2015.

[3] M. E. Ravitch, "The Operative Treatment of Pectus Excavatum," Ann. Surg., vol. 129, no. 4, pp. 429–444, 1949.

[4] J. Kelly et al., "Pectus excavatum: historical background, clinical picture, and indications for operation," Semin. Pediatr. Surg., vol. 17, no. 3, pp. 181-193, 2008.

[5] R. E. Kelly et al., "Prospective multicenter study of surgical correction of pectus excavatum: design, perioperative complications, and early outcomes of the Nuss procedure," J. Am. Coll. Surg., vol. 205, no. 2, pp. 313-322, 2007.

[6] F. Croitoru et al., "Experience with over 1000 minimally invasive repairs of pectus excavatum," J. Pediatr. Surg., vol. 47, no. 1, pp. 189-195, 2012. [7] G. W. Holcomb, "Minimally invasive repair of pectus excavatum," Pediatr. Surg. Int., vol. 21, no. 3, pp. 139-143, 2005.

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