Pectus excavatum (PE) is the most common congenital deformity of the chest wall, characterized by an inward depression of the sternum (breastbone) and the ribs attached to it. Often called “funnel chest” or “sunken chest,” the condition presents a spectrum of severity, ranging from a barely noticeable dip to a deep, caved-in appearance. While the primary concern was once cosmetic, medical investigation now focuses on the deformity’s relationship with heart function. The physical alteration of the chest cavity raises questions about whether the heart and lungs have adequate space to operate.
The Anatomy of Pectus Excavatum
Pectus excavatum is a structural malformation where the sternum and adjacent costal cartilages are displaced backward into the thoracic cavity. This creates a concavity in the chest that can be symmetric or asymmetric, often involving the third through seventh costal cartilages and the lower portion of the sternum. The severity of the inward displacement typically increases during adolescent growth spurts, making the condition more noticeable during the teenage years. The underlying cause is suspected to be an overgrowth of the costal cartilage, which pushes the sternum inward. This physical outcome reduces the distance between the sternum and the vertebral column, resulting in compression of the internal organs.
Mechanical Effects on Heart Placement and Function
The physical intrusion of the sternum into the chest cavity directly impacts the space available for the heart, leading to predictable mechanical consequences. The inward pressure causes the heart to be physically displaced, typically shifting its position to the left side of the chest. This displacement is often accompanied by rotation and compression of the heart chambers, primarily affecting the right ventricle and the right atrium. This external compression is most significant during the diastolic phase of the cardiac cycle, when the heart muscle relaxes and fills with blood. The reduced volume of the right heart chambers due to external pressure can impede complete filling, a phenomenon known as impaired diastolic filling, which translates directly to a lower stroke volume and a reduced cardiac output, especially during exertion.
Specific Cardiac Conditions Linked to Pectus Excavatum
The mechanical effects of the chest wall deformity can lead to specific, measurable cardiac issues. One frequently observed association is Mitral Valve Prolapse (MVP), where the leaflets of the mitral valve bulge into the left atrium during contraction. Studies indicate that the prevalence of MVP is significantly higher in individuals with PE, a finding linked to the continuous mechanical distortion of the heart’s structure. Compression and displacement can also irritate the electrical system, resulting in various arrhythmias or irregular heart rhythms. Patients may experience palpitations or premature heartbeats, leading to a chronic reduction in exercise tolerance, fatigue, and shortness of breath during physical activity.
Diagnostic Tools and Treatment Options
Evaluating the cardiac impact of pectus excavatum requires a multi-modal approach to quantify the severity of the deformity and its functional effects. The most common measurement is the Haller Index, calculated from a cross-sectional computed tomography (CT) scan. This index compares the chest’s transverse width to the shortest distance between the sternum and the spine; an index of 3.25 or higher indicates a moderate to severe condition. An echocardiogram is routinely performed to visualize the heart’s structure, confirm MVP, and assess heart function and displacement. To evaluate functional consequences, a cardiac stress test measures the patient’s peak oxygen uptake and overall exercise capacity.
For patients with significant symptoms or a high Haller Index, surgical correction is often recommended to relieve pressure on the heart and lungs.
Surgical Procedures
- The minimally invasive Nuss procedure involves inserting a curved metal bar to push the sternum outward.
- The more traditional Ravitch procedure involves removing the deformed costal cartilage and repositioning the sternum.