Left ventricular herniation and incarceration with infarction secondary to a pericardial defect in a dog

A 2-year-old spayed female Labrador Retriever with clinical signs of heart failure presented to necropsy with a pericardial defect with most of the left ventricle non-reducibly herniated into the pleural space. The herniated cardiac tissue was constricted by a ring of pericardium that allowed subsequent infarction, evidenced by a marked depression on the epicardial surface. A congenital defect was considered more likely than a traumatic cause, since the margin of the pericardial defect was smooth and fibrous. Histologically, the herniated myocardium was acutely infarcted while the epicardium at the defect margin was markedly compressed, including the coronary vessels. This appears to be the first report of ventricular cardiac herniation with incarceration and infarction (strangulation) in a dog. Similar cardiac strangulations may rarely occur in humans with congenital pericardial defects or acquired pericardial defects secondary to blunt trauma or thoracic surgery.