1. Date of download: 5/29/2016 Copyright © The American College of Cardiology. All rights reserved. From: Emerging Applications for Transseptal Left Heart Catheterization: Old Techniques for New Procedures J Am Coll Cardiol. 2008;51(22):2116-2122. doi:10.1016/j.jacc.2008.01.061 Gross Examination of the FO From the Right Atrium Right atrial view of the atrial septum with limbic ledge seen superiorly (below dotted line) and depressed fossa ovalis (FO) inferiorly. SVC = superior vena cava. Figure Legend:

2. Date of download: 5/29/2016 Copyright © The American College of Cardiology. All rights reserved. From: Emerging Applications for Transseptal Left Heart Catheterization: Old Techniques for New Procedures J Am Coll Cardiol. 2008;51(22):2116-2122. doi:10.1016/j.jacc.2008.01.061 Fluoroscopic Views During Transseptal Puncture (A) Transseptal puncture performed in the anteroposterior projection with fluoroscopic imaging. The pigtail catheter marks the location of the aortic valve, and the tip of the transseptal dilator engages the fossa ovalis inferiorly and medially to the aortic valve. (B) Transseptal puncture performed in the lateral fluoroscopic projection. The transseptal dilator engages the fossa ovalis in the lower third of the imaginary line (thin dashed line) connecting the pigtail catheter (aortic valve) and the posterior wall of the left atrium (heavy dashed line). (C) Transseptal puncture performed in the right anterior oblique projection with fluoroscopic imaging. The transseptal dilator (TC) engages the fossa ovalis posterior to the pigtail catheter (aortic valve) but anterior to right atrial silhouette (dashed line). Figure Legend:

3. Date of download: 5/29/2016 Copyright © The American College of Cardiology. All rights reserved. From: Emerging Applications for Transseptal Left Heart Catheterization: Old Techniques for New Procedures J Am Coll Cardiol. 2008;51(22):2116-2122. doi:10.1016/j.jacc.2008.01.061 2- and 3-Dimensional Echocardiographic Views During Transseptal Puncture (A) 2-dimensional transesophageal echocardiographic imaging depicts tenting (arrow) of the atrial septum into the left atrium (LA). (B) 3-dimensional transesophageal echocardiographic imaging visualizes tenting (arrow) of the atrial septum. RA = right atrium. Figure Legend:

4. Date of download: 5/29/2016 Copyright © The American College of Cardiology. All rights reserved. From: Emerging Applications for Transseptal Left Heart Catheterization: Old Techniques for New Procedures J Am Coll Cardiol. 2008;51(22):2116-2122. doi:10.1016/j.jacc.2008.01.061 Pressure Tracing From Transseptal Needle During Transseptal Catheterization Right atrial (RA) pressure wave form becomes blunted (BP) as the needle engages the septum. After the needle passes through the septum, a left atrial (LA) pressure wave form is seen. Figure Legend:

5. Date of download: 5/29/2016 Copyright © The American College of Cardiology. All rights reserved. From: Emerging Applications for Transseptal Left Heart Catheterization: Old Techniques for New Procedures J Am Coll Cardiol. 2008;51(22):2116-2122. doi:10.1016/j.jacc.2008.01.061 New Transseptal Catheterization Techniques Using a Radiofrequency Catheter or an Internal Jugular Vein Approach (A) A radiofrequency catheter is inserted into dilator and sheath and ablates a thickened atrial septum to cross into the left atrium (courtesy of Radiofrequency Transseptal System, Baylis Medical, Montreal, Quebec, Canada). (B) The LA-Crosse system uses a stabilizer sheath, a guide catheter, and a flexible puncture screw to safely cross the atrial septum from the right internal jugular vein (courtesy of St. Jude Medical, St. Paul, Minnesota). Figure Legend: