A funnel chest, more commonly known as pectus excavatum, is a congenital deformity characterized by a depression of the sternal bone. The etiology, as well as risk factors, remain unclear. Signs and symptoms may not be present initially, but the eventual compression of the heart in adulthood can cause marked symptoms, especially in the absence of clinical suspicion about funnel chest being the underlying cause.
Funnel chest (medically termed pectus excavatum) is considered to be a rather common congenital disease, seen in 1 in 1,000 live births. In the United States, 1 in 300 Caucasian children is diagnosed with a funnel chest  . A significant predilection toward male gender has been reported, with the male-to-female ratio ranging from 2:1 to even 9:1  . Pectus excavatum rarely causes symptoms in childhood and infancy (which is why physicians often inform parents that there is no reason for concern and that the problem is cosmetic in nature only). But many reports have illustrated the importance of this condition in the pathogenesis of debilitating cardiopulmonary symptoms     . The reason why symptoms do not appear until adulthood, however, is unexplained as yet. The most probable theory suggests the loss of chest wall elasticity in adulthood, which leads to reduced compliance and direct compression of the depressed sternum on the cardiac structures, specifically the right ventricle . As a result, previously healthy patients may complain of dyspnea, shortness of breath, palpitations (particularly after exercise), persistent fatigue and asthma-like symptoms    . If the diagnosis is not made, prolonged compression of the chest can cause reduced lung volume, cardiac compression and valvular heart disease (mitral regurgitation or prolapse of the mitral valve)  . Funnel chest is often associated with scoliosis (in about 15% of cases), while connective tissue disorders, such as Marfan syndrome and Ehlers Danlos syndrome may also be associated with it   .
The initial diagnosis of a funnel chest is made during a physical examination as early as infancy when inspection and palpation of the chest wall confirms a cup-shaped concavity in the sternum  . The concavity is well defined, deep and more prominently involves the lower portion of the sternal bone  . Depression of 4th-7th costal cartilages can be observed in a significant number of individuals, in which case the concavity might be broader . Other notable findings include a pot-belly posture, forward-drifted shoulders, a heart murmur on cardiac auscultation and arrhythmia in severe cases  . On the other hand, when previously healthy patients describe cardiopulmonary signs and symptoms during history taking, an earlier finding of a funnel chest must raise clinical suspicion toward this disorder as the underlying cause. Family history, an integral part of the patient interview, is also an important feature, as up to 43% of pectus excavatum cases have a positive family history for the condition . Imaging studies, however, are the gold standard in confirming congenital abnormalities of the chest wall, and either computed tomography (CT) or magnetic resonance imaging (MRI) can be used   , which both show the abnormal site of the sternum and its compression of the heart. Pulmonary function tests, electrocardiography (ECG) and echocardiography (either transthoracic or transesophageal) are recommended during workup, in order to assess the function and structure of the heart.