EFFECT OF ATRIAL SEPTAL OCCLUSION ON MITRAL AREA AFTER INOUE BALLOON VALVOTOMY

The purpose of this study was to examine the influence of the atrial c ommunication created during transseptal passage of the Inoue balloon c atheter on calculated mitral valve area after balloon valvotomy for se vere mitral stenosis. Even in the absence of oxymetric evidence for a shunt, atrial septal puncture may result in left-to-right shunting of blood with reported spurious increases in postvalvotomy mitral valve a rea calculations ranging from 16-29% in prior studies, Occlusion of th e septal puncture site after double balloon valvotomy has previously b een shown to result in decreased postvalvotomy mitral valve area deter minations. We evaluated 20 patients undergoing mitral dilation. Each p atient had three postvalvotomy measurements made: (1) with the Inoue b alloon catheter positioned across the septum, (2) during septal occlus ion with a 7F balloon-tip catheter, and (3) without any catheters acro ss the septum. With the lnoue catheter across the septum after success ful valvotomy, the cardiac output was 4.6 +/- 1.5 L/min and the calcul ated mitral valve area was 1.7 +/- 0.5 cm(2), No difference was found in either cardiac output or valve area when the septum was unobstructe d by catheters. During septal occlusion, however, the postvarvotomy ca rdiac output decreased to 4.3 +/- 1.3 L/min (P<0.001) and the calculat ed mitral area decreased by 12% to 1.5 +/- 0.5 cm(2) (P<0.001). The ca lculated mitral valve areas determined with the lnoue catheter in plac e after valvotomy were in agreement with echo derived data. Although s tatistically significant differences in post-lnoue valvotomy cardiac o utput and calculated mitral valve area were found during septal occlus ion, these differences were small. Furthermore, echocardiographic valv e area measurments agreed with invasively determined mitral valve area s regardless of whether or not the septum was occluded. We conclude th at septal occlusion is not necessary for valve area measurement after lnoue balloon mitral valvotomy. (C) 1994 Wiley-Liss, Inc.