Abstract
BACKGROUND: Coronary sinus (CS) injury is a potentially serious complication during left ventricular lead implantation. Its risk may be reduced by recognizing atypical guidewire trajectories. CASE SUMMARY: A 71-year-old man with wild-type transthyretin cardiac amyloidosis underwent implantation of a cardiac resynchronization therapy device. During left ventricular lead placement, CS dissection occurred owing to the cannulation of a guiding catheter into the vein of Marshall (VOM) via an inadvertent guidewire. The patient remained hemodynamically stable, the CS dissection resolved spontaneously, and the procedure was completed successfully. DISCUSSION: The VOM courses between the left atrial appendage and the left pulmonary veins. The third mogul, which corresponds to the left atrial appendage, may serve as a useful anatomical landmark to indicate inadvertent guidewire entry into the VOM. TAKE-HOME MESSAGE: Identifying the third mogul on anteroposterior fluoroscopic view could facilitate early detection of inadvertent guidewire entry into the VOM and help prevent coronary venous complications.