Transseptal puncture (TSP) performed with the Brockenbrough (BRK) needle is technically demanding and carries potential risks. The back end of the percutaneous transluminal coronary angioplasty (PTCA) guidewire is blunt and flexible, with good support, it can puncture the right ventricle-free wall, which is thicker than the atrial-septum. The guidewire is thin and easy to manipulate. This study evaluated the performance of TSP with a PTCA guidewire and microcatheter without a needle. The back end of a PTCA guidewire was advanced into the Tiger (TIG) catheter, within the SL1 sheath, to puncture the fossa ovalis (FO) under fluoroscopy. Subsequently, the microcatheter was inserted into the left atrium (LA) above the guidewire, and the front end of the guidewire was exchanged in the LA. After the puncture site was confirmed by contrast, the TIG catheter and a 0.032 inch wire were advanced into the LA. Finally, the sheath, with the dilator, was advanced over the wire into the LA. The safety margin of this method was tested in a pig model. The puncture was successful in all seven pigs tested with a puncture-to-sheath entry time of 20 minutes and no procedure-related complications. The method was successfully used to perform a difficult TSP in a patient with an extremely tortuous inferior vena cava, in whom puncture with a BRK needle had repeatedly failed. Cardiologists may use the PTCA guidewire and microcatheter as an alternative to the needle while performing TSP in special conditions, such as an extremely tortuous inferior vena cava.