TSP Crosser is an integrated transseptal system that includes a method to engage the fossa ovalis precisely and efficiently using an extendable radiopaque loop wire and a steerable sheath. The system can precisely navigate a flexible needle for accurate and optimal left-atrium access. After the puncture, the steerable sheath serves as a guiding catheter for left-side procedures, including transcatheter mitral repair/replacement, PVL closure, atrial fibrillation ablation, and left-atrial appendage occlusion.