What common symptom might a patient with cardiac tamponade exhibit?

A patient with cardiac tamponade is likely to exhibit distended jugular veins due to increased pressure in the thoracic cavity that affects venous return to the heart. This condition leads to elevations in central venous pressure, which can cause the jugular veins to become visibly distended when the patient is in a sitting or semi-recumbent position. This sign is part of the classic triad of symptoms known as Beck's triad, which includes hypotension, muffled heart sounds, and distended neck veins.

The other symptoms listed, while they may occur in different clinical scenarios, are not characteristic of cardiac tamponade. Low-grade fever often indicates infection or inflammation, increased heart rate can occur in various conditions but is not specific to tamponade, and unilateral leg swelling typically suggests issues related to venous obstruction or peripheral edema rather than cardiac tamponade. Thus, the presence of distended jugular veins is a hallmark sign specifically associated with this condition.