Validation of Noninvasive Measures of Left Ventricular Mechanics in Children: A Simultaneous Echocardiographic and Conductance Catheterization Study

Abstract

Introduction The accuracy of echocardiography in evaluating left ventricular (LV) contractility has not been validated in children. The objective of this study was to compare echocardiographic measures of contractility vs. those derived from pressure-volume loop (PVL) analysis in children. Methods Patients with relatively normal loading conditions undergoing routine left heart catheterization were prospectively enrolled. PVLs were obtained via conductance catheters. The gold-standard measure of contractility, end-systolic elastance (Ees), was obtained via balloon occlusion of one or both vena cavae. Echocardiograms were performed immediately after PVL analysis under the same anesthetic conditions. Single-beat estimations of echocardiographic Ees were calculated using four different methods. These estimates were calculated using a combination of non-invasive blood pressure readings, ventricular volumes derived from 3D echocardiography, and Doppler time intervals. Results Of 24 patients, 18 patients were heart transplant recipients, 6 patients had a small patent ductus arteriosus or small coronary fistula. Mean age was 9.1 ± 5.6 years. The average invasive Ees was 3.04 ± 1.65 mmHg/mL. Invasive Ees correlated best with echocardiographic Ees by method of Tanoue (r = 0.85, p < 0.01) with a mean difference of −0.07 mmHg/mL (95% limits of agreement: −2.0, 1.4 mm Hg/mL). Conclusion Echocardiographic estimates of Ees correlate well with gold-standard measures obtained via conductance catheters in children with relatively normal loading conditions. The use of these non-invasive measures in accurately assessing LV contractility appears promising and merits further study in children.

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

“…Last, although Ees and Ea have been validated in children, they have not been well studied in preterm infants or validated in the setting of acute changes in loading conditions or contractility. 4 …”

“…12 To use these measures more routinely, single beat estimations of echocardiographic Ees and Ea (ie, estimates of Ees and Ea that do not require load alteration to be measured) have been developed and validated in children. 4,13 Ea was calculated as (0.9 × systolic blood pressure/stroke volume). Ees was calculated as (0.9 × systolic blood pressure/end-systolic volume).…”

“…4 The use of these simple measures is attractive because they allow us to gain insight into the contractile and loading states that predispose a preterm neonate to postligation syndrome and may ultimately be more powerful predictors of outcome than the conventional measures used in previous studies. The objective of this study was to determine the association between these preoperative novel echocardiographic measures of LV performance and postoperative outcomes after PDA ligation in preterm infants.…”

Left ventricular pumping during the transition–adaptation sequence in preterm infants: impact of the patent ductus arteriosus

“…Invasive evaluation is not feasible in the fragile patient group of preterm infants. However, the sophisticated and diverse methodology (18)(19)(20)(21) to estimate LV pump function from echocardiographic parameters (end-systolic volume (ESV), SV, and from blood pressure (BP)) that has already been applied in both adults (17,22) and children (19,20,23,24) appeared to be a noninvasive alternative for preterm infants.…”

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

“…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.…”