Final answer:
Pericardiocentesis is the procedure that involves puncturing the pericardial sac to withdraw fluid, mainly performed to treat conditions like cardiac tamponade, which is fluid accumulation in the pericardial space that affects the heart's function.
Step-by-step explanation:
The procedure that involves surgical puncture of the fibrous sac surrounding the heart to withdraw fluid for diagnostic or therapeutic purposes is known as pericardiocentesis. The pericardium or pericardial sac separates the heart from other mediastinal structures and consists of two fused layers: the fibrous pericardium that protects the heart and maintains its position in the thorax, and the parietal pericardium that is lined with a serous membrane.
Cardiac tamponade is a condition that occurs when excess fluid accumulates within the pericardial space, increasing pressure on the heart and preventing full relaxation, which can dramatically affect heart function and may even lead to death if not treated with procedures like pericardiocentesis.