A case of right coronary artery chronic total occlusion with difficulty in retrograde system establishment.

Advances in microcatheters (MCs) enables the establishment of retrograde systems for the treatment of chronic total occlusion (CTO). However, there are still cases in which establishing a retrograde system is difficult because the guidewire or MC cannot pass through due to calcification, stenosis, or tortuosity. We present a case of a 56-year-old man with angina. Coronary angiography revealed a CTO of the right coronary artery (RCA). Although we started an antegrade approach at first, the guidewire went to subintimal lumen. We switched to a retrograde approach. Although the guidewire passed through posterolateral (PL) channel, the MC could not pass due to a stenosis at the junction of the main RCA trunk. Therefore, we negotiated the septal channel; however, it could only be guided in the peripheral direction. When the guidewire was more advanced in the peripheral direction, it crossed the guidewire that had previously passed through the PL channel. Then, when a balloon was delivered via the septal channel and trapped the guidewire from the PL channel, the MC was successfully delivered via the PL channel. After establishing the retrograde system, revascularization succeeded smoothly. In conclusion, this technique can be one option for the treatment of CTO patients. < Even if a guidewire passes retrogradely, the establishment of the retrograde system may be difficult in some cases since the microcatheter cannot pass retrogradely. This technique can be one of the effective options for the treatment of patients with chronic total occlusion when establishing a retrograde system is difficult.>.