1

What are the causes of anterior chest wall deformities?

Pectus excavatum (90%) (Figure 1A).

Pectus carinatum (5-7%) (Figure 1B).

Cleft sternum.

Pentalogy of Cantrell (midline developmental defects):

a)

defect of the lower sternum;

b)

anterior diaphragmatic hernia;

c)

defect in the supraumbilical anterior abdominal wall (usually an omphalocoele);

d)

defect in the diaphragmatic pericardium;

e)

intracardiac abnormality with ectopia cordis.

Asphyxiating thoracic dystrophy (Jeune syndrome).

Poland syndrome.

Spondylothoracic dysplasia (Jarcho-Levin syndrome).

2

What is the pathophysiology of pectus excavatum?

Pectus excavatum (PE) is caused by dorsal deviation of the sternum and the 3rd to 7th rib or costal cartilage, resulting in a concave depression of the anterior chest wall.

Depending on the severity of PE, deviation of the thoracic organs (Figure 2) and spinal deformities (such as scoliosis in 15-21% of patients) may also be present.

Although PE may be present at birth, it usually worsens during the pubertal growth spurt.

3

What is the epidemiology of pectus excavatum?

PE is the most common congenital chest wall abnormality and has an incidence of approximately 1 in 300-400 live births.

Males are more commonly affected, with a male to female ratio of 3:1.

A positive family history is present in up to 40% of cases.

The condition is usually present at birth, with 80% diagnosed within the first 2 years of life.

PE is usually an isolated anomaly, with <1% having an underlying connective tissue disorder.

4

What is the aetiology of pectus excavatum?

Although the exact aetiology of PE is unknown, abnormal mechanical forces during growth are thought to contribute to its development.

In patients with a connective tissue disorder, an intrinsic abnormality of the costochondral cartilage is thought to be the underlying reason for the development of PE. Occurrence of PE in patients with connective tissue disorders includes Marfan syndrome 5-8%, Ehlers-Danlos syndrome 3% and Sprengel’s deformity 0.6%.

No specific genetic defects have been described to date.

5

What are the effects of pectus excavatum on respiratory function?

Both spirometry (measurement of air flow out of the chest on exhalation at rest) and plethysmography (measurement of lung volumes) are usually reduced by approximately 10-20% of the predicted values.

In children with otherwise normal airways and lung parenchyma, the sole physiological explanation for decreased spirometry values is chest wall malformation.

As these are otherwise healthy patients without concurrent pulmonary disease, with pliable chest walls and huge physiologic reserve, the abnormal respiratory function is usually only unmasked by formal exercise testing.

In patients with recurrent PE, a significant restrictive lung disease pattern may be present, with spirometric values as low as 50% of predicted.

6

What is the effect of pectus excavatum on cardiac function (Figure 3)?

The haemodynamic effects of PE are controversial.

Direct cardiac compression may result in reduced cardiac output due to a reduction in stroke volume.

The degree of severity of PE, however, does not correlate directly with functional impairment. In some PE patients with a deep chest (increased anteroposterior distance), the heart may never be compressed despite severe sternal depression.

Improvements in cardiac function (including ejection fraction, and right ventricular systolic and diastolic indices) have been reported both in the early postoperative period and long-term following surgical correction.

Mitral valve prolapse, as a direct result of cardiac compression, is more prominent than in an age-matched population (17% PE vs. 1% normal population).

Dysrhythmias, including 1° heart block, right bundle branch block or Wolff-Parkinson-White syndrome, may be present in up to 15% of patients.

Congenital heart disease is present in 2% of patients with PE.

7

What are the symptoms associated with pectus excavatum?

Cosmetic abnormality with concavity of the anterior chest wall.

Poor body image, which may lead to withdrawal from social and sporting activities, depression and, in some cases, attempted suicide.

Compression of the thoracic organs may result in chest pain, fatigue, dyspnoea on exertion, respiratory infections, asthma symptoms, palpitations or syncopal episodes.

8

What are the signs associated with pectus excavatum?

Concavity of the anterior chest wall, with different variants including:

a)

focal or cup-shaped deformity (most common type, Figure 4A);

b)

broad, shallow, saucer-shaped deformity (second most common type, Figure 4B);

c)

long furrow or trench deformity, which is usually asymmetrical (third most common type);

d)

mixed pectus carinatum and excavatum deformities occur in 5% of cases.

Tall, thin patient with forward-drifting hunched shoulders.

Asymmetry and associated sternal tilt.

Costal flaring.

Other features of connective tissue disorders, including scoliosis (fixed or reversible), joint laxity and striae may be present.

Heart murmurs should be excluded, particularly mitral valve prolapse.