Pectus excavatum is the most common structural chest wall deformity, characterized by a visible indentation or sunken appearance of the sternum. This anatomical variation results from the abnormal growth of the costal cartilage connecting the ribs to the sternum, which pushes the bone inward. Although often present at birth, the indentation typically becomes more pronounced during periods of rapid growth, such as adolescence. While often considered primarily a cosmetic concern, pectus excavatum can have significant physiological consequences in severe cases. The inward pressure exerted by the sternum can limit the space available for the heart and lungs, potentially leading to functional issues.
The Visual Spectrum of Pectus Excavatum
Pectus excavatum deformities are classified based on the depth of the depression, often described as mild, moderate, or severe. In mild cases, the sternal dip is slight and may be barely noticeable, usually causing no physical symptoms. Moderate cases show a distinct indentation that is clearly visible and may cause aesthetic discomfort. Severe cases present the most pronounced depression, creating a deep, “scooped-out” or “funnel” appearance. This deep concavity may also cause the lower ribs to protrude, a visual feature often called “flared ribs.”
The visual presentation is also categorized by the shape and symmetry of the depression. A cup-shaped deformity is localized to the lower sternum, appearing discrete and deep at a single point. In contrast, a saucer-shaped deformity involves a broader, shallower concavity across the chest plate. The deformity can be either symmetrical, with the deepest point centered, or asymmetrical, where the sternum is rotated or pushed to one side.
Physical Impact and Objective Measurement
The inward displacement of the sternum can create functional consequences by crowding the internal organs. Patients with moderate to severe pectus excavatum may experience shortness of breath, particularly during physical activity, due to lung compression. The heart, which sits behind the sternum, can be physically displaced or compressed, leading to symptoms such as heart palpitations, a fast heart rate, or decreased endurance.
To move from visual observation to objective diagnosis, physicians rely on the Haller Index (HI) to quantify the severity of the deformity. The Haller Index is calculated from a cross-sectional Computed Tomography (CT) scan taken at the deepest point of the depression. This index is the ratio of the chest’s transverse diameter (the distance across the inside of the ribcage) divided by the shortest distance between the sternum and the spine.
A normal chest has a Haller Index value around 2.5, while a value greater than 3.25 is considered severe and often qualifies a patient for surgical intervention. The CT scan provides this precise numerical value and allows doctors to visualize the degree of heart displacement or lung compression. This objective measurement is used alongside exercise tolerance tests and cardiac evaluations to determine if corrective treatment is warranted.
Understanding Treatment Pathways
The approach to treating pectus excavatum depends on the severity, the patient’s age, and the presence of functional symptoms. For milder cases, or for younger patients whose chest wall is still flexible, non-surgical options are available. The Vacuum Bell device uses suction to create a negative pressure seal on the chest, mechanically lifting the sunken sternum over time.
For patients with a Haller Index over 3.25 or those experiencing significant cardiopulmonary symptoms, surgical correction is recommended. The most common approach is the minimally invasive Nuss procedure, which involves placing a custom-bent metal bar behind the sternum through small incisions on the side of the chest. This bar is then flipped to push the sternum outward and is left in place for two to three years to permanently reshape the chest wall.
The modified Ravitch procedure is an alternative, more invasive open repair technique. This method involves removing portions of the abnormally grown cartilage and repositioning the sternum. This method is often preferred for older adolescents or adults, as well as for complex or recurrent cases where the chest wall is less pliable. Both surgical methods aim to correct the deformity, improving both the appearance and the underlying heart and lung function.