the diagnosis of tamponade can be confirmed with trans-thoracic echocardiography (tte), which should show a large pericardial effusion and diastolic collapse of the right ventricle and right atrium. chest x-ray usually shows an enlarged cardiac silhouette ("water bottle" appearance) and clear lungs. pulmonary congestion is typically not seen because equalization of diastolic pressures constrains the pulmonary capillary wedge pressure to the intra-pericardial pressure (and all other diastolic pressures).