Constrictive pericarditis results from thickening and fibrosis of the parietal and/or visceral pericardium, which become very rigid. This prevents the heart from filling adequately in diastole. The pericardial layers may fuse, obliterating the pericardial space, or the pericardial space may contain a small volume of fluid (constrictive-effusive disease). | Constrictive pericarditis results from thickening and fibrosis of the parietal and/or visceral pericardium, which become very rigid. This prevents the heart from filling adequately in diastole. The pericardial layers may fuse, obliterating the pericardial space, or the pericardial space may contain a small volume of fluid (constrictive-effusive disease). |