“…Pneumopericardium is extremely rare and can be caused by physical trauma to the pericardium (e.g., nonpenetrating and penetrating thorax trauma) [17], barotrauma (e.g., mechanical ventilation) [18], acute asthma attack, coughing, Heimlich and Valsalva maneuvers, pregnancy and labor, and fistulas of the pericardium (e.g., thorax tumors, infections, and abscesses). Rarely, it may develop due to pericarditis caused by spontaneous gas-producing microorganisms, invasive procedures (e.g., thoracotomy, tracheostomy, tracheostomy closure [19], thoracentesis, pericardiocentesis [20–23], surgical pericardiotomy [24], endomyocardial biopsy [1], pacemaker insertion [25]), complications of cardiac resynchronization therapy [26], or Boerhaave syndrome (e.g., spontaneous esophageal wall perforation) [27].…”