No coronary sinus atrial tachycardia Ouyang reported 9 patients with no coronary sinus atrial tachycardia, all 9 patients had P waves in I and AVL upright, V1 and V2 negative/positive during tachycardia, 7 cases had II, III and AVF negative/positive or negative, and the remaining 2 cases, 1 case had P waves in II, III and AVF negative, 1 case had P waves II and III negative, and AVF isotonic line. The earliest excitation electricity of the right atrial excitation marker was near the HB area, 52.9±8.7 ms earlier than the CS potential, and the earliest local electrogram of the right atrium had a clear HB potential. The earliest excitation in the left atrium was opposite the HB area in the anterior septum, earlier than the CS potential 50.2±8.3 ms, and the earliest excitation in the left atrium was 2-5 ms later than the earliest excitation in the right atrium, with no HB potential in the left atrial local electrogram. All patients had no interstitial HB potentials in the NCC. The aortic sinus is located in the center of the heart, and the anterior and superior edges of the NCC are the septal surfaces of the left and right atria adjacent to the upper part of the atrioventricular junction. The right edge of the NCC is connected to the right atrial septal surface, the left edge is connected to the left atrial septal surface, and a portion of the right atrial wall is connected to the NCC in the upper part of the central fibrous body.