ROLE OF LEFT ATRIAL APPENDAGE IN LEFT ATRIAL RESERVOIR FUNCTION AS EVALUATED BY LEFT ATRIAL APPENDAGE CLAMPING DURING CARDIAC-SURGERY

We evaluated the role of left atrial appendage (LAA) in the left atria l (LA) reservoir function by assessing the changes in LA flow dynamics after LAA clamping during cardiac surgery. The subjects were 8 patien ts who had undergone coronary artery bypass grafting (CABG) and 7 who had undergone mitral valvular surgery due to mitral regurgitation. We recorded transmitral, pulmonary venous and LAA flow velocity patterns by intraoperative transesophageal pulsed Doppler echocardiography, mon itoring LA pressure before and 5 minutes after LAA clamping. The maxim al LAA area was significantly greater, and the peak late diastolic LAA emptying flow velocity was significantly lower before LAA clamping in the mitral regurgitation group than in the CABG group. In both groups , the peak early and late diastolic transmitral and pulmonary venous f low velocities significantly increased, and the peak second systolic p ulmonary flow velocity significantly decreased during LAA clamping. Th ere were no significant changes in heart rate and systemic systolic bl ood pressure during LAA clamping, whereas mean LA pressure and maximal LA dimension significantly increased in both the groups. The LA press ure-volume relation during ventricular systole shifted upward and to t he left during LAA clamping, and the slope was steeper in the MR group than in the CABG group. We conclude that the LAA is more compliant th an the LA main chamber, and plays an important role in LA reservoir fu nction in the presence of LA pressure and/or volume overload. (C) 1998 by Excerpta Medica, Inc.