See below. Typically, an imaging modality, commonly echocardiography, is used to image the heart and the pericardial space. After local anesthesia is given, a long needle is inserted under the guidance of the echo to the pericardial space and the fluid will be withdrawn with a syringe. Typically, a plastic tube will then be inserted and left in place to drain into a bag for a few days.
Surgeon. There are several ways of draining a pericardial effusion. Your cardiothoracic surgeon can explain to you excactly how he/she is planning to drain it.