Left ventricular dysfunction after open repair of simple congenital heart defects in infants and children: Quantitation with the use of a conductance catheter immediately after bypass

Objective: Quantification of myocardial injury after the simplest pediatric operations by load-independent indices of left ventricular function, using conductance and Mikro-Tip pressure catheters (Millar Instruments, Inc., Houston, Tex,) inserted through the left ventricular apex, Methods: Sixteen infants and children with intact ventricular septum undergoing cardiac operations had left ventricular function measured, immediately before and after bypass, Real-time pressure-volume loops were generated by conductance and Mikro-Tip pressure catheters placed in the long-axis via the left ventricular apex, and preload was varied by transient snaring of the inferior vena cava, Results: Good quality pressure-volume loops were generated in 13 patients (atrial septal defects, n = 11; double-chambered right ventricle, n = 1; supravalvular aortic stenosis, n = 1; age 0.25 to 14.4 years, weight 3.1 to 46.4 kg), Their mean bypass time was 41 +/- 14 minutes and mean aortic crossclamp time 27 +/- 11 minutes, End-systolic elastance decreased by 40.7% from 0.34 +/- 0.17 to 0.21 +/- 0.15 mm Hg-1 . ml(-1) . kg(-1) (p < 0.001), There were no significant changes in the slope of the stroke work-end-diastolic volume relationship, end-diastolic elastance, time constant of isovolumic relaxation, and normalized values of the maxima and minima of the first derivative of developed left ventricular pressure, Conclusion: Load-independent indices of left ventricular function can be derived from left ventricular pressure-volume loops generated by conductance and Mikro-Tip pressure catheters during the perioperative period in infants and children undergoing cardiac operations, Incomplete myocardial protection was demonstrated by a deterioration in systolic function after even short bypass and crossclamp times.