This report describes our experience with a modified sheath transseptal catheter system. The sheath technique allows for introduction of various catheters into the left heart, including a uniquely designed pigtail catheter intended for use with this system. Fifty-three patients underwent successful transseptal catheterization, 44 of whom had severe native aortic valve stenosis and seven with suspected prosthetic aortic valve dysfunction. The technique provides optimal ventriculographic and hemodynamic information as well as improved access to the left heart in patient with aortic valve disease.