Pulsus paradoxus is associated with

Pulsus paradoxus is associated with

The blood pressure in the right arm is 95/70, and in the lower extremity it is 45/25. The most likely diagnosis is

Ice applied to the face has been ineffective in the patient. The treatment of choice is

An 8-year-old female presents with chest pain of 1 day's duration. Five days prior to the pain, she had fever, chills, and myalgias. Physical examination reveals an uncomfortable, anxious, afebrile patient with tachycardia, no murmur, and distant heart sounds. The chest x-ray is shown in Figure 19-2. There is a paradoxical pulse of 22 mm Hg. The most likely diagnosis is