The aim of this chapter is to focus on the double balloon technique. With the double balloon antegrade technique, the left atrium is accessed through the interatrial septum (antegrade) from the right femoral vein using standard transseptal catheterization equipment. Mullins sheath is inserted into the left atrium, through which an end-hole balloon tipped catheter can be floated across the mitral valve, avoiding the chordae tendineae. It is then turned in the left ventricular apex using a curved tipped guidewire and advanced out the aortic valve. A long guidewire (260 cm) is then introduced through this catheter from the femoral vein across the atrial septum and the mitral and aortic valves, terminating in the descending aorta. This procedure can be repeated, or a special double lumen catheter used to place a second guidewire adjacent to the first one. Advantages and disadvantages of double balloon technique are also discussed in this chapter.