ABSTRACT

Left atrial access has been a challenge in cardiac catheterization since the earliest cardiac surgical procedures mandated accurate assessment of left atrial pressure in the 1940s. The real stimulus for the rebirth of transseptal catheterization has been the electrophysiology laboratory, where left-sided ablations have resulted in exponential growth. Modern left atrial catheterization by puncture of the interatrial septum is a half-century old. The interatrial septum is embryologically derived from growth of the septum primum and secundum toward the endocardial cushions. The initial use of transseptal puncture for direct hemodynamic assessment of left heart pressures has become uncommon given the small but significant risk associated with the procedure, the low risk of pulmonary wedge pressure measurement, and the availability of noninvasive alternatives in most cases. The transseptal route can avoid catheter entrapment and artifact; pullback to the mitral valve allows differentiation between apical or mid-cavitary obliteration and true outflow obstruction.