Visualization apparatus and methods for transseptal access are described herein where intravascular access across a septal wall is facilitated via devices which provide for direct visual viewing of tissue area. Such a system may include a deployment catheter and an attached imaging hood deployable into an expanded configuration. In use, the imaging hood is placed against or adjacent to the tissue to be imaged in a body lumen that is normally filled with an opaque bodily fluid such as blood. A translucent or transparent fluid can be pumped into the imaging hood until the fluid displaces any blood leaving a clear region of tissue to be imaged via an imaging element in the deployment catheter. Any number of therapeutic tools or a guidewire can be passed through the catheter and into the imaging hood for crossing the septal wall and passing the guidewire or instruments therethrough.