An indentation or depression in the center of the chest wall can be concerning. This anatomical variation, which affects the sternum or breastbone, is a common structural feature present from birth or developing during periods of rapid growth. While this sunken appearance is often cosmetic, understanding the underlying physical cause and potential physiological impact is important.
Pectus Excavatum: The Primary Structural Cause
The most frequent reason for a dent in the chest is Pectus Excavatum (PE), which translates to “hollowed chest.” This congenital chest wall deformity causes the sternum and attached ribs to grow inward, creating a caved-in or funnel-like appearance. PE is the most common congenital anomaly of the chest wall, affecting approximately 1 in every 300 people, and is seen much more frequently in males than in females.
The exact cause is not fully understood, but the prevailing theory suggests it results from an abnormal growth rate of the costal cartilage, the flexible tissue that connects the ribs to the sternum. This abnormal development pushes the sternum backward toward the spine. The deformity typically involves the third through the seventh costal cartilages, with the deepest point of the indentation often occurring near the xiphisternum, the lower tip of the breastbone.
The appearance of the indentation varies significantly from person to person. It may be uniformly centered and symmetrical, or asymmetrical, with the depression more pronounced on one side, often rotating the sternum slightly. The inward pull on the sternum sometimes causes the lower ribs to flare outward, making the central depression appear more prominent. Minor developmental variations or a prominent but normal xiphoid process can sometimes be misidentified as a chest depression.
How This Depression Can Affect Internal Function
While the primary concern for many individuals with Pectus Excavatum is the cosmetic appearance, a severe depression can compromise the limited space within the thoracic cavity, potentially affecting the heart and lungs. In mild cases, heart and lung function are generally normal, and the condition is considered purely aesthetic. Functional implications become more pronounced as the severity of the sternal depression increases.
The heart is located directly behind the sternum and can be displaced or rotated by a deeply sunken chest wall. This displacement can sometimes lead to compression of the right atrium, the chamber of the heart that receives deoxygenated blood. This pressure or rotation may cause symptoms such as heart palpitations or contribute to the presence of a heart murmur.
The functional impact on the heart is most often noticeable during physical activity rather than at rest. Compression can limit the heart’s ability to fill with blood and pump it out efficiently during strenuous exercise. A more severe deformity can lead to a measurable decline in maximum oxygen uptake during exercise, indicating a reduced capacity for endurance and physical performance.
The lungs are also affected because the reduced volume of the chest cavity restricts their ability to fully expand. This restriction results in reduced lung capacity, leading to shortness of breath, particularly during rigorous activity or exercise. The combination of restricted lung expansion and reduced cardiac output often manifests as decreased exercise tolerance and increased fatigue.
Next Steps: When to Seek Medical Evaluation and Treatment Options
Individuals with a chest depression should seek a medical evaluation if they experience any associated physical symptoms, such as chest pain, a rapid or irregular heartbeat, or significant shortness of breath during exertion. A medical consultation is also warranted if the condition causes substantial psychological distress due to the appearance of the chest.
The evaluation process typically begins with a physical examination and imaging studies to determine the severity of the condition. A Computed Tomography (CT) scan is often used to calculate the Haller Index, a standardized measurement of the chest deformity. The Haller Index is calculated by dividing the chest’s internal transverse diameter by the shortest distance between the sternum and the spine. A normal chest has an index around 2.5, while a measurement greater than 3.25 is generally considered a severe deformity and a common indication for surgical intervention.
Functional testing, such as pulmonary function tests and an echocardiogram, will also be performed to assess the impact on the lungs and heart. Treatment options depend on the severity and presence of symptoms. For mild cases, management may involve monitoring, physical therapy, or the use of non-surgical devices like the vacuum bell, which applies suction to gently pull the sternum forward over time.
Surgical correction is typically reserved for patients with a high Haller Index or significant functional impairment. The two most common surgical approaches are the minimally invasive Nuss procedure, which involves placing a curved metal bar behind the sternum to push it outward, and the open Ravitch procedure, which involves removing the abnormal cartilage. The goal of these treatments is to improve the chest’s contour and relieve pressure on the heart and lungs, thereby improving cardiorespiratory function and exercise capacity.