The Giant "a" Wave of the Left Atrial Appendage.

IN an exploration of the left atrium via an atrial septal defect during a recent cardiac catheterization in this laboratory, the catheter tip entered the left atrial appendage. An exaggerated "a" wave observed in the pressure contour from the left atrial appendage was striking and exceeded in amplitude the "a" wave from the left atrium proper. Following a similar observation shortly thereafter in a second patient with a patent foramen ovale, a concerted effort was made to enter the appendage on all subsequent catheterizations of the left atrium. To our knowledge, there is no other report in the literature regarding pressure contour in the left atrial appendage. "Falsely" elevated pressure curves from the right atrial appendagel and right atrium2 have, however, been observed. Methods Attempts to introduee the catheter into the left atrial appendage were made in 14 patients besides the two that prompted the study. These 14 patients included one with patent foramen ovale, four with ostium secundum, and one with ostium primum defects of the atrial septum, eight with rheumatic mitral stenosis or insufficieney, and one with myocarditis. In order to estimate the frequency of iniadvertent catheterization of the left atrial appendage, left atrial pressure tracings recorded from a similar group of 15 patients over a 15-month period prior to the initiation of this study were reviewed with particular attention to pressure contour. Standard technics were employed in all cardiac catheterizations. Catheters for left-heart catheterization were introduced percutaneously.3 4 Transseptal left atrial puncture was performed by the technic described by Ross et al.5 except in two