Congenital chest wall deformities may be categorized as (1) pectus excavatum, (2) pectus carinatum, (3) Poland syndrome, (4) sternal defects, and (5) miscellaneous anterior chest wall defects. While most patients present during childhood, some may present in early adulthood as well.
Pectus excavatum, or “funnel chest,” is a congenital deformity characterized by posterior depression of the middle to inferior portion of the sternum and posterior curvature of the associated costal cartilages (Fig. 139-2). Generally, the manubrium and first and second ribs are normal. The severity of the depression varies and is usually asymmetric with a deviation to the right side. Shamberger and Welch reported that most cases (86%) are diagnosed at or within a few weeks of birth.1 Although it was once commonly believed that children would “outgrow” this deformity, the severity of the sternal depression may increase during periods of rapid growth.
Pectus excavatum is the most common congenital chest wall deformity in children, with a reported incidence of 1 in 300 to 400 to 1 in 1000 live births. A male predominance is observed, with boys reported to be affected three times more often than girls.1 The etiology of pectus excavatum is unknown. Theories include intrauterine pressure, rickets, and abnormalities of the diaphragm, including congenital diaphragmatic hernia and diaphragmatic agenesis.2 Although no clear pattern of inheritance is known, Shamberger and Welch note that 35% of patients report a positive family history for chest wall deformities.1
Pectus excavatum may be accompanied by other abnormalities. In a study of 704 children with pectus excavatum, musculoskeletal abnormalities, such as scoliosis or kyphosis, were identified in 19%. Pectus excavatum has been associated with congenital heart defects (1.5%) and connective tissue disorders such as Marfan syndrome or Ehlers–Danlos syndrome in up to 6.4%.3 Although many pediatric patients are asymptomatic, symptoms can worsen with age, with increased physical activity or worsening of deformity during the second growth spurt.4 A recent multicenter prospective trial demonstrated that approximately two-thirds of patients reported dyspnea or other chest symptoms with limited exercise tolerance (64.5%), shortness of breath at rest (62.1%), and chest pain on exertion (51.1%). Chest pain unrelated to exertion (32%), and palpitations (11%) also were reported. Pain on exertion and at rest was presumably musculoskeletal in origin.3 In addition, children may experience psychological distress as a consequence of their cosmetic appearance.
Physical examination reveals middle to inferior sternal depression of varying severity. Usually the depression is asymmetric, most commonly with sternal deviation to the right side and subsequent shift of the heart to the left. Many studies have investigated the altered cardiac function by means of electrocardiogram (ECG), echocardiogram, nuclear medicine test, and angiogram. A significant number of patients are found to have right atrial and ventricular compression or mitral valve prolapse. Mitral valve prolapse has been reported in 17% to 65% of patients compared to only 1% in the normal pediatric population. Dysrhythmias have been found in 16% of patients.5 Most of these studies also have shown decreased exercise tolerance consequent to decreased stroke volume. At rest, the cardiac index is normal, but the response to moderate exertion is below predicted values.
Given the common subjective complaints of shortness of breath, pulmonary function testing has been used in numerous studies to attempt to quantify any abnormality.6–8 However, the severity of symptoms often does not correlate well with objective findings in pulmonary and cardiac function. In most patients, only a mild-to-moderate (10%–15%) reduction in forced expiratory volume in 1 second (FEV1) and vital capacity is identified.3
There are several methods of “grading” the severity of deformity by radiographic imaging. The pectus (or Haller) index is a ratio between the transverse diameter and anterior–posterior diameter. The transverse diameter is the maximal transverse diameter of the thorax at its widest point. The anterior–posterior diameter indicates the distance between the sternum and the anterior spine at the deepest level of depression.9 Normal is approximately 2.5, greater than 3.5 is considered abnormal, with greater than 5.0 considered severe. Another method compares the distance from the point closest to the posterior sternum to the anterior spine and the distance between the spine and sternum at the angle of Louis.1 Unfortunately, neither method consistently correlates the severity of symptoms to an objective index.
Surgery remains the primary form of therapy for these patients. While the cosmetic benefit cannot be debated, the effect on cardiopulmonary function is less clear. A recent meta-analysis of the effect of surgery on long-term follow-up found that most patients experience a decrease in pulmonary function over time, thought to be related to loss of chest wall compliance due to restricted anterior chest wall motion despite symptomatic improvement.10 From a cardiac standpoint, the data are conflicting. Currently, there is no consensus as to whether surgical repair improves cardiac function.10–12 The surgical treatment of pectus excavatum is detailed in Chapters 140 and 141.
Pectus carinatum occurs much less frequently than pectus excavatum, comprising only 10% of chest wall deformities. It is a congenital deformity characterized by outward sternal protrusion with anterior displacement of the middle and lower sternum and associated costal cartilages (Fig. 139-3). Pectus carinatum may be classified as chondrogladiolar (symmetric or asymmetric), mixed pectus carinatum and excavatum, and chondromanubrial. The chondrogladiolar type is the most common. It is described as an anterior protrusion of the body of the sternum with protrusion of the lower costal cartilage. As reported by Shamberger and Welch, the symmetric chondrogladiolar type is more common.1 The mixed subtype is often composed of both elements of carinatum and excavatum. The chondromanubrial subtype, also referred to as “pouter pigeon,” involves an anterior protrusion of the manubrium along with the second and third costal cartilages.
Like pectus excavatum, carinatum is much more common in males than in females (4:1). However, in contrast to pectus excavatum, it is not usually recognized until adolescence. A family history is again present in approximately 30% of patients. Scoliosis is the most commonly associated musculoskeletal deformity, whereas fewer than 5% of patients with pectus carinatum have associated congenital heart disease. Symptoms are uncommon in childhood but may progress into adolescence. It has been suggested that shortness of breath may be related to decreased chest wall compliance with increased chest diameter. In pectus carinatum, there is increased residual volume and reduced vital capacity which may also account for some symptoms.
Again, surgical repair by osteotomy is the main form of treatment. Surgical therapy provides excellent results with low morbidity in as many as 97% of patients.13 The surgical treatment of pectus carinatum is discussed in Chapter 140.
Poland syndrome is the congenital absence of the pectoralis major and minor muscles associated with syndactyly (fused fingers) (Fig. 139-4). It is also associated with abnormalities of the ribs, chest wall depressions, and abnormalities of the breasts. Thoracic involvement may range from hypoplasia of the sternal head of the pectoralis major and minor muscles with normal ribs, to complete absence of the anterior portions of ribs two to five and costal cartilages. Breast involvement may range from complete absence of the breast (amastia) and nipple (athelia) to mild hypoplasia. Hand deformities primarily involve the central three digits and may include syndactyly (fused fingers) and brachydactyly (hypoplasia). Poland syndrome occurs in 1 in 30,000 to 32,000 live births and is not often familial.14 It is more common in females than males at a ratio of 3:1. The etiology is not well understood.
Sternal defects are rare chest wall deformities that may be classified as cleft sternum or ectopic cordis (Fig. 139-5A,B). Sternal clefts typically involve only the upper sternum; ectopic cordis involves the lower sternum. The presumed embryologic cause is failure of ventral fusion of the sternum, resulting in sternal clefts, thoracic ectopia cordis, and thoracoabdominal ectopia cordis.
Sternal defects: (A) cleft sternum, (B) ectopic cordis.
Cleft sternum in infants results from nonfusion of the sternal plates at about the eighth week of gestation. The cleft typically involves the upper sternum where the sternum has a complete or partial separation. The remainder of the sternum is normal, as is the diaphragm, pericardium, location of the heart, and overlying skin coverage. Omphaloceles do not occur in these children and it is rarely associated with intrinsic congenital heart disease. In ectopic cordis (thoracic and thoracoabdominal), the sternal cleft involves the inferior portion of the sternum and is associated with an abnormal diaphragm, pericardium, and location of the heart. Intracardiac anomalies are very common. In thoracic ectopic cordis, the lethal factor is the extrathoracic location of the heart without its pericardial coverage. In thoracoabdominal ectopic cordis (the Cantrell Pentology), the associated five features include (1) inferior sternal cleft, (2) anterior diaphragmatic defect, (3) absence of pericardium at the diaphragmatic defect, (4) an omphalocele, and (5) intrinsic cardiac abnormalities.15 Although surgical repair of isolated cleft sternum is routinely successful, repair of ectopia cordis is associated with a high mortality rate.