Apparatus is provided of locating the fossa ovalis in a patient by locating at least one of the His bundle, the plane of the interatrial septum, and the coronary sinus ostium in a patient, and thereafter locating the fossa ovalis on the basis of one or more predetermined distances between these locations. Software is also provided that can determine and display the location of the fossa ovalis in a patient based on predetermined distances between the locations. Such software can for example be provided within an electroanatomical system. Methods of determining the location of the fossa ovalis, performed by either a clinician or a central processing unit-controlled surgical system, are also provided and determined using predetermined measurements from defined locations. An apparatus for locating the fossa ovalis and performing a transseptal puncture is also provided.
