OBJECTIVETo study the morphologic classification and its clinical significance of giant left atrium (GLA) combined with mitral valvular disease.

METHODSBetween January 1993 and December 1999, a total of 62 consecutive patients with mitral valvular disease, whose preoperative left atrial endodiastolic volume index >/= 300 ml/m(2) or endosystolic diameter >/= 6.0 cm, were enrolled as research candidates. Morphologically, GLA was classified by Q Hierarchical cluster analysis according to the right or left side cardiothoracic ratio of the left atrium (r- or l-LATR) on an anteroposterior chest roentgenogram and the ratio of the distant diameter of the left main bronchus to the approximate diameter of the left main bronchus (LBDd/Dp) or to the trachea (LB/TR) on an left anterior oblique chest roentgenogram.

RESULTSAccording to r-LATR and l-LATR, the morphology of GLA was classified clinically into three types: type L (l-LATR >/= 0.6 and r-LATR < 0.58), type R (r-LATR >/= 0.58 and l-LATR < 0.6) and type B (r-LATR >/= 0.58 and l-LATR >/= 0.6). According to LBDd/Dp and LB/TR, GLA in type L and B was further classified into two subtypes, respectively: left posterior downward type (L(I) and B(I)), in which LBDd/Dp is equal or exceeds 0.38 or LB/TR is equal or exceeds 0.33, and left posterior upward type (L(II) and B(II)), in which LBDd/Dp is less than 0.38 or LB/TR less than 0.33.

CONCLUSIONThe morphologic classification of GLA may represent the main pathophysiological changes of GLA and might be a guideline for the selection of the optimal plication procedures of GLA in patients with valve diseases.