Adam B. Greenbaum et al. JACEP 2015;1:434-441 Online Video 1 Procedure sequence of a representative patient. Right atrial angiography is performed in this patient using a 8.5-F SL3 sheath and a 7-F balloon wedge end-hole catheter. Through these, a 0.014-inch guidewire and 2.4-F microcatheter are advanced across the wall of the right atrial appendage into the pericardium. After insufflation of 90 ml of CO2 through the microcatheter, the pericardium is entered using a subxiphoid needle and guidewire in a lateral fluoroscopic projection. Adam B. Greenbaum et al. JACEP 2015;1:434-441 American College of Cardiology Foundation