Ventriculo-Arterial Coupling for Predicting Cardiac Index Increase in Infants after Heart Surgery.

Abstract

To test the ability of ventriculo-arterial coupling to predict cardiac index response after milrinone infusion. This was a retrospective, observational study. We measured arterial blood pressure and echocardiography-derived variables, including cardiac index, systemic vascular resistance index, arterial elastance, and end-systolic ventricular elastance before and after 18-24 hours of milrinone infusion. Ventriculo-arterial coupling was calculated as the ratio of arterial elastance to end-systolic elastance. Infants with over 15% increase in the cardiac index were defined as cardiac index responders. Logistical regression was used to evaluate predictors of cardiac index responders. We enrolled 92 infants who underwent cardiac surgery and received milrinone infusion, of which 45 infants were cardiac index responders. High ventriculo-arterial coupling (odds ratio= 5.534, 95% confidence interval 2.339 to 13.090) and high arterial elastance (odds ratio= 3.035, 95% confidence interval 1.459 to 6.310) were independently associated with cadiac index responders. Pre-milrinone ventriculo-arterial coupling predicted cardiac index responsiveness with a cutoff value of 1.12 (area under the curve = 0.900, 95% CI [0.819 to 0.953], p < 0.0001). Furthermore, we observed a decrease in the infant's ventriculo-arterial coupling, arterial elastance, and systemic vascular resistance index after milrinone infusion. In infants with congenital heart disease after surgery, a pre-milrinone ventriculo-arterial coupling greater than 1.12 can predict the increase in the cardiac index following milrinone infusion.