Pectus Excavatum

Overview

Pectus excavatum is the most common congenital chest wall anomaly, comprising approximately 90% of all congenital chest wall defects. Incidence is 1 in 300 live births; five times more common in males than females; more prevalent in Caucasians.

Pectus excavatum

A funnel-shaped chest due to abnormalities of the anterior 4–5 ribs with posterior depression of the sternum.

Aetiology

• Idiopathic in the majority
• Familial predisposition — approximately one-third have family history (not proven genetic)
• Associated anomalies: Marfan's syndrome (most important), Noonan's syndrome, collagen vascular diseases, congenital lung hypoplasia, diaphragmatic hernia, homocystinuria, fetal alcohol syndrome
• Acquired pectus: severe chronic lower respiratory tract obstruction → sustained accessory muscle use → high intrathoracic pressure → pectus formation

Pathophysiology

Overgrowth of costal cartilage pushes the sternum posteriorly. Dorsal deviation of the sternum and 3rd–7th costal cartilages creates the characteristic concave anterior chest wall depression. The degree of cardiac and pulmonary compression correlates with the severity of the deformity.

Clinical features

Investigations

• CXR: posterior displacement of lower sternum on lateral view; apparent cardiomegaly and downward angulation of anterior ribs on PA view
• CT chest: measures Haller index; identifies associated anomalies; cardiac displacement
• PFT: restrictive pattern; reduced RV on body plethysmography
• Echocardiogram: reduced LVEF; assess for MVP; quantify cardiac compression
• CPET: accurate assessment of functional impairment — particularly useful in borderline cases

Indications for surgery

• Haller index >3.25
• Symptomatic respiratory impairment
• Significant cosmetic deformity (patient-driven)
• Progressive deformity
• Cardiac compression or dysrhythmia attributable to the deformity

Surgical procedures

Ravitch procedure (open repair)

Goal: remove abnormal rib cartilage while preserving the perichondrium — allows regrowth of rib cartilage to the sternum in a more anatomical position.

1. Excision of deformed cartilage with preservation of perichondrium
2. Division of xiphoid from sternum
3. Division of intercostal bundles from sternum
4. Transverse sternal osteotomy
5. Fixation in over-corrected position (internal fixator or metal strut)

Nuss procedure — MIRPE (minimally invasive repair)

Originally described by Donald Nuss. Internal bracing without cartilage resection — the deformed cartilage remodels around the corrective bar over 2–3 years.

1. Two small lateral thoracic incisions
2. Thoracoscope inserted via separate port for visualisation
3. Subcutaneous tunnels created across the chest
4. Curved steel pectus bar passed from one incision across the retrosternal space to the other side
5. Bar flip — bar is rotated 180° to elevate the sternum into correct position
6. Bar fixed with stabiliser and pericostal sutures
7. Bar removed after approximately 2–3 years

Pectus carinatum

Protrusion deformity — anterior bowing of the sternum and costal cartilages ("pigeon chest"). Far less common than pectus excavatum. Functional impairment is rare. Management: bracing (orthotics) is first-line in adolescence and achieves correction in the majority when started early. Surgery (modified Ravitch procedure) is reserved for failed bracing, adult presentation, or severe deformity.