THERMODILUTION LEFT-SIDED CARDIAC-OUTPUT FOR VALVE AREA DETERMINATIONAFTER BALLOON MITRAL VALVOTOMY

This study was conducted to establish the validity of left-sided cardi ac output measurement with a Swan-Gent catheter and assess its accurac y in estimating mitral valve area (MVA) by the Gorlin formula. The use of right-sided cardiac output after balloon mitral valvotomy (BMV) ca n give inaccurate measurements for Gorlin-derived MVA because of the a trial septal defect (ASD) created during the procedure. The left-sided cardiac output was measured with a Swan-Ganz catheter (proximal port in the left atrium and then in the Left ventricle, and distal port in the ascending aorta) in 10 consecutive patients before and after BMV. Gorlin-derived MVA cardiac output by this method was compared with (1) Gorlin-derived MVA by means of right-sided cardiac output with and wi thout balloon occlusion of the ASD and (2) MVA measured by echocardiog raphy. Before BMV, a close agreement with a good correlation between l eft-sided and right-sided cardiac output was found (r = 0.83, p = 0.00 6). Furthermore, Gorlin-derived MVA by cardiac output with either meth od was comparable with valve area by echo. After BMV, left-sided cardi ac output correlated well (r = 0.92, p = 0.0002) and was comparable wi th right-sided cardiac output with occlusion of the ASD (mean differen ce 0.17 +/- 0.49 L/min, p = 0.3) but was significantly lower than the value obtained with open ASD (mean difference 0.93 +/- 0.77 L/min, p = 0.004). Comparison of the correspondent MVAs yielded similar results. Gorlin-derived MVA with left-sided cardiac output and MVA by echo wer e also similar. Thermodilution left-sided cardiac output with a Swan-G anz catheter is feasible and reliable, and improves the accuracy of Go rlin-derived MVA after BMV. This method may eliminate the need to clos e ASD for right-sided cardiac output measurement and may obviate the n eed for a second venous approach to BMV.