Pectus excavatum is a deformity characterized by the inward and posterior depression of the sternum along with the costal cartilages, forming a boat-shaped or funnel-shaped appearance. The deepest point of the depression is typically at the junction of the sternal body and the xiphoid process. It may appear symmetric or asymmetric and is the most common chest wall deformity, accounting for approximately 90% of all such cases.
The mechanism underlying the development of pectus excavatum remains unclear. Some researchers believe it results from uncoordinated growth of the ribs, with faster growth in the lower ribs than in the upper ribs, thereby pushing the sternum posteriorly and causing the deformity. Others suggest it may occur due to a shortened central tendon of the diaphragm, which causes diaphragm fibers attached to the lower sternum and xiphoid process to pull the sternum backward. The condition has a higher prevalence in males than females, with some cases demonstrating familial inheritance or co-occurring with congenital heart disease.
Clinical Presentation
In infancy, mild compressive symptoms of pectus excavatum may often be overlooked. Some children may present with inspiratory stridor or sternal retraction, although the underlying cause of airway obstruction is frequently undetermined. Affected children are commonly thin, prone to upper respiratory infections, and may have limitations in physical activity. Symptoms such as palpitations, shortness of breath, and difficulty breathing may be observed during exertion. In addition to chest wall deformities, affected individuals may also exhibit mild kyphosis or a protruding abdomen as part of a distinctive body type.
In adolescents or adults, pulmonary function tests often show a significant reduction in forced expiratory volume and maximum ventilatory capacity. Electrocardiograms may indicate clockwise rotation of the heart. Lateral chest X-rays typically reveal posterior depression of the lower sternum with a reduced distance between the sternum and the spine. Chest CT scans not only confirm the diagnosis of pectus excavatum but also allow for an assessment of its severity using the Haller index, which helps in treatment decision-making and surgical planning. The Haller index is calculated as the ratio of the transverse diameter of the thoracic cavity at the most depressed level of the sternum (A) to the anteroposterior distance between the posterior surface of the sternum and the anterior surface of the vertebral body at the same level (B). The mean Haller index in normal individuals is 2.52. A value greater than 3.2 is diagnostic of pectus excavatum. Values between >3.2 and ≤3.25 represent mild pectus excavatum, those between >3.25 and 3.5 represent moderate cases, and values greater than 3.5 indicate severe pectus excavatum.
Treatment
Mild cases of pectus excavatum often do not require specific intervention, as the deformity may self-correct with age. Severe cases may impair growth, respiratory and circulatory function, and contribute to psychological stress, making surgical treatment necessary. The optimal timing for surgery is typically between 2 and 5 years of age, as early intervention tends to produce better outcomes. The most commonly employed procedure is the minimally invasive Nuss operation. This technique involves the placement of specially designed metal bars behind the deformed sternum and in front of the heart via small incisions along the anterior axillary line on both sides of the chest, under thoracoscopic guidance. This method does not require resection of the sternum or ribs, results in satisfactory outcomes, and is less invasive. The corrective bars are usually removed in a secondary procedure after 2 to 3 years, depending on the progression of the chest wall correction.
Conventional surgical methods such as the Ravitch operation (sternal elevation), the Wada procedure (sternal turnover), and the pedicled sternal turnover procedure are now rarely used due to their relatively higher surgical trauma.