Bi-ventricular function assessed intraoperatively before and after anatomical correction of transposition of the...

After anatomical correction of transposition of the great arteries (TGA), the left ventricle (LV) is forced to develop systemic pressures without having had time for adaptation. Thus, one might expect dilatation of the LV at least in the very early intraoperative period following the operation. In nine patients with TGA aged 8-24 days (median 9.5 days) which were selected for arterial switch operation (ASO), Dacron-patch mounted thin piezoceramic transducers were attached intraoperatively by fibrin glue to opposite epicardial surfaces of the right (RV) and/or LV for continuous assessment of external minor diameters (RVD, LVD; sonomicrometry) before and after correction. Right and left ventricular pressures (RVP, LVP) were measured simultaneously and pressure-diameter loops were generated. Right and left ventricular power indices (RVPi, LVPi: = HRxVPxVsD) was calculated from heart rate, ventricular pressures, and systolic shortening of the respective ventricular diameter (RVsD, LVsD). Data obtained during circulatory steady-state immediately before extra-corporeal circulation (ECC) and up to 45 min after ECC were compared. By avoiding volume overload (CVP < or = 10 mmHg) at weaning off ECC and by lowering the systemic vascular resistance and, thus, LV afterload (approximately 8 micrograms.kg-1 min-1 dobutamine), the LV developed systemic pressure (70 +/- 7 vs. 41 +/- 4 mmHg) at unchanged diastolic LV end-diastolic pressure (LVedP) (10 +/- 3 mmHg). Left ventricular power index increased by 45 +/- 25%, although the extent of systolic shortening of LVD was reduced by 20 +/- 10%. Simultaneously, the RV was effectively unloaded (RVedP: 8 +/- 3 vs 11 +/- 6 mmHg; RVP: 39 +/- 7 vs 53 +/- 9 mmHg; RVPi: -42 +/- 27%).(ABSTRACT TRUNCATED AT 250 WORDS)