• Damage to the myocardium during pericardial paracentesis has occasionally been severe enough to result in pericardial tamponade and death. Anamil experiments here described showed that contact of the tip of the needle with the myocardium could be detected electrocardiographically if the needle was connected in such a way as to constitute an exploring electrode with the machine set as in recording chest leads. Contact with the myocardium is indicated by elevation of the S-T or the P-R segment, depending on whether the ventricle or the auricle is disturbed. This technique has been used in 40 cases of pericardial paracentesis. All were without complication, though the ventricular cavity was entered inadvertently in six instances. The danger of unintended puncture of the ventricle can be minimized by recognizing the existence of a lag between the appearance of changes in the electrocardiogram and the communication of this fact to the operator.
Bishop LH, Estes EH, McIntosh HD. THE ELECTROCARDIOGRAM AS A SAFEGUARD IN PERICARDIOCENTESIS. JAMA. 1956;162(4):264–265. doi:10.1001/jama.1956.02970210004002