Preoperative echocardiographic measures of left ventricular mechanics are associated with postoperative vasoactive support in preterm infants undergoing patent ductus arteriosus ligation

Abstract

Objective Preoperative risk factors associated with poor outcomes after patent ductus arteriosus ligation in preterm infants have not been well defined. The aim of this study was to determine the association between preoperative echocardiographic measures of left ventricular mechanics and postoperative clinical outcomes after patent ductus arteriosus ligation. Methods Preterm infants less than 90 days of age with no other significant congenital anomalies who underwent patent ductus arteriosus ligation between 2007 and 2015 were considered for retrospective analysis. The primary outcome was peak postoperative vasoactive inotropic score. Conventional echocardiographic measures of ventricular size, function, and patent ductus arteriosus size were performed. Echocardiographic single-beat, pressure-volume loop analysis estimates of contractility (end-systolic elastance) and afterload (arterial elastance) were calculated. Ventriculoarterial coupling was assessed using the arterial elastance/end-systolic elastance ratio. Multivariable linear regression was performed using clinical and echocardiographic data. Results Echocardiograms from 101 patients (42.5% male) were analyzed. We found a statistically significant association between vasoactive inotropic score and both end-systolic elastance and arterial elastance. No patient with arterial elastance/end-systolic elastance greater than 0.78 (n = 32) had a vasoactive inotropic score 20 or greater. Analysis of our secondary outcomes found associations between preoperative end-systolic elastance and postoperative urine output less than 1 mL/kg/h at 24 hours, creatinine change greater than 0.5 mg/dL, and time to first extubation. Conclusions End-systolic elastance and arterial elastance were the only predictors of postoperative vasoactive inotropic score after patent ductus arteriosus ligation in preterm infants. Those neonates with increased contractility and low afterload were at highest risk for elevated inotropic support. These findings suggest a role for echocardiographic end-systolic elastance and arterial elastance in the preoperative assessment of preterm infants undergoing patent ductus arteriosus ligation.

“What we know is little, and what we are ignorant of is immense”

“…Because the measure of elastance is derived from the slope of the relationship between pressure and volume, elastance captures both the pulsatile and the resistive components of afterload. 4 Gray and colleagues' report 5 in this issue of the Journal stresses the importance of preoperative left ventricular mechanics in the outcome of preterm infants undergoing patent ductus arteriosus ligation. The noninvasive measurement of arterial elastance and left ventricular end-systolic elastance as measures of afterload (in lieu of wall stress) are central to ascertaining the state of the left ventricle before surgery.…”

“…The criterion for the measurement of elastance is by conductance during cardiac catheterization. Gray and colleagues 5 provide an alternative method, one that is based on their previous clinical work 6 and uses transthoracic echocardiography. Their method was derived from data on predominantly healthy subjects after transplant with normal pulmonary to systemic flow ratio determined by 3-dimensional echocardiography with measurements averaged over three beats.…”

“…This method has not been validated in healthy premature and term infants, however, as a basis to support conclusions about the physiology in the cohort of patients in the study of Gray and colleagues. 5 Furthermore, elastance data measurements in other disease states are not provided. Moreover, their primary outcome of peak postoperative vasoactive inotropic score has not been validated as a predictor of morbidity and mortality in patients after closed-heart operations.…”

“…8 Furthermore, some fear postligation syndrome, which has been suggested as a contributor to bronchopulmonary dysplasia and neurodevelopmental impairment. 8,9 Perhaps with the use of fine-grain preoperative noninvasive echocardiographic measurements, 5 such as elastance, a better risk stratification profile for preterm babies with patent ductus arteriosus can be formulated and sway the pendulum toward medical optimization followed by surgical ligation when indicated.…”

Circulatory Insufficiency and Hypotension Related to the Ductus Arteriosus in Neonates

“…Early TNE at 1 h post-ligation can help to identify potential cardiovascular compromise, as critically low LVO (<200 mL/kg/min) predicts the development of PLCS ( 68 ). Preoperative echocardiographic assessment of ventriculo–arterial coupling may also play a role in detecting PLCS, as infants with higher contractility (LV end-systolic elastance) in the setting of lower afterload (arterial elastance) perioperatively will not respond as favorably to acute changes in loading conditions that are evident with PDA ligation ( 74 , 80 ).…”