Congenital absence of the pericardium

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Overview
Congenital absence of the pericardium or congenital defects of the pericardium (1/10,000 autopsies) comprise partial left (70%), right (17%), or total bilateral (extremely rare) pericardial absence. About 30% of patients have additional congenital abnormalities. Most patients with a total absence of pericardium are asymptomatic. However, homolateral cardiac displacement and augmented heart mobility impose an increased risk for traumatic aortic type A dissection.

Associated congenital abnormalities

 * Atrial septal defect
 * Patent ductus arteriosus
 * Mitral stenosis
 * Tetralogy of Fallot

Pathopysiology
Normally, the aortopulmonary window is covered by pericardium and contains some fat. Most pericardial defects are partial and occur on the left side. Left-sided absence of the pericardium allows interposition of lung tissue between the aorta and the main segment of the pulmonary artery. Occasionally, there is bulging of the left atrial appendage through the defect. The heart usually rotates toward the left.

Diagnosis
Patients who have a pericardial defect without associated congenital abnormalities are often asymptomatic. The chest x-ray is typical, but the diagnosis is confirmed by echocardiography and computed tomography (CT) / magnetic resonance imaging (MRI).

Plain film

 * Apparent elevation of the cardiac apex
 * Prominent pulmonary artery segment
 * Lucency caused by interposition of the lung between the aorta and main pulmonary artery segment.
 * In patients with complete absence of the pericardium, the size of the cardiophrenic space is increased on the frontal chest radiograph.

CT

 * Interposition of lung tissue between the aorta and the main segment of the pulmonary artery

Treatment
Excision of the atrial appendage and surgical pericardioplasty (Dacron, Gore-tex, or bovine pericardium) is indicated for imminent strangulation.

Complications
Partial left side defects can be complicated by cardiac strangulation caused by herniation of the left atrial appendage, atrium, or left ventricle through the defect (chest pain, shortness of breath, syncope, or sudden death).