361 - Validation of Echocardiographic Measures of Pulmonary Hypertension in Neonatal Lambs

Publication Number: 1345.361

Jakob D. Van Boerum, University of Utah School of Medicine, Salt Lake City, UT, United States; Andrew Rebentisch, University of Utah School of Medicine, Salt Lake City, UT, United States; Yasmine White, University of Utah School of Medicine, Salt Lake City, UT, United States; Mar Janna Dahl, University of Utah School of Medicine, Salt Lake City, UT, United States; Matthew Douglass, University of Utah School of Medicine, Salt Lake City, UT, United States

Background: Neonatal pulmonary hypertension (PH) remains a significant clinical challenge. A key gap in PH research is the lack of validation for echocardiographic indices of PH against invasive hemodynamic measurements. Cardiac catheterization, the gold standard for assessing PH, is not feasible in most neonates. Animal models that recapitulate the developmental and physiological characteristics of human neonates are essential to address this gap. The neonatal lamb model closely resembles human neonatal physiology and is well suited for studying the relationship between echocardiographic and invasive measures of PH.

Objective: To determine whether echocardiographic indices of PH correlate with invasive measures of right ventricular and pulmonary artery pressure in neonatal lambs.

Design/Methods: Term lambs (n=3) breathing room air on day of life 7 and preterm lambs (n=6) born at 128 days gestation and supported with mechanical ventilation for approximately 3 weeks had terminal echocardiograms and right heart catheterizations. We measured left ventricular end-systolic eccentricity index, pulmonary artery acceleration time normalized to RV ejection time (PAAT:RVET), RV fractional area of change, RV to LV end-systolic diameter ratio, RV end diastolic area, and LV ejection fraction by echocardiogram. A catheter was inserted into the external jugular and advanced into the right heart to measure right ventricular and pulmonary artery pressure.

Results: Simple linear regression revealed significant correlations between PAAT/RVET and both right ventricle (R² = 0.6189, p = 0.03) and pulmonary artery pressure (R² = 0.6515, p = 0.02). The slopes of the other echocardiographic measures were not statistically significant.

Conclusion(s): Studies have demonstrated that PAAT/RVET may be a reliable non-invasive echocardiographic parameter for estimating pulmonary vascular resistance and diagnosing PH in select neonatal populations. Our finding that PAAT/RVET significantly correlates with invasively measured right ventricular and pulmonary artery pressures supports its use for serial, non-invasive evaluation of PH in neonatal lambs. The neonatal lamb model is a physiologically relevant model for investigating the mechanisms of neonatal PH and evaluating potential therapeutic interventions.