Cardiac tamponade is a condition in which fluid accumulates in the pericardial cavity. It can result from pericardial effusion or from leakage of blood from the heart or proximal portions of the great vessels. The increased pressure within the pericardial sac leads to decreased cardiac filling during diastole and therefore reduced systolic blood pressure. Because of the reduced pumping capacity of the heart, there is increased pressure in the venous system, leading to the distension of the jugular venous system. Deep vein thrombosis often occurs in the lower limbs and increases the risk of pulmonary embolism. The other answers listed are conditions that affect pulmonary function rather than cardiac functions.