Figure 1. Gross examination of the right atrium shows white area of discoloration along the cavo-tricuspid isthmus region and an area of hemorrhage between the coronary sinus and the tricuspid valve. Three levels of the cavo-tricuspid isthmus are shown: lateral isthmus, central isthmus and paraseptal isthmus. A projected course of the right coronary artery (red line) demonstrates its anatomic relation to the cavo-tricuspid isthmus. CTI: cavo-tricuspid isthmus; FO: foramen ovale; TV: tricuspid valve; CS: coronary sinus; RCA: right coronary artery; TT: tendon of Todaro; LI: lateral isthmus; CI: central isthmus; PSI: paraseptal isthmus.
Figure 4. Microscopic examination shows cross-sections of the right coronary artery taken from the region of the ablation site demonstrating fat necrosis (red asterisk) and reactive changes to the fat and soft tissues of the right atrioventricular junction. Within the one-fifth of the vessel’s media, the smooth muscle cells have loss of nuclei (lack of blue colored nuclei) as shown by the black asterisk when compared to the normal smooth muscle cells with preserved nuclei (blue asterisk). Right coronary artery is narrowed by calcified atherosclerotic plaque with areas of acute plaque hemorrhage.