Fig. 2

Coronary angiography: a Left main coronary artery (LMCA) reveals no significant disease; b left anterior descending branch coronary artery (LAD) and left circumflex coronary artery (LCX) showing no significant disease; c Observation of the right coronary artery (RCA) showing 90% stenosis in the proximal segment; d The stenosis of RCA was relieved after the intracoronary administration of nitrates