Abstract 20144: Increasing Preload Permits Maintenance of Cardiac Output During Rapid Atrial Pacing in Infant Piglets but is Associated With Possible Right Heart Diastolic Impairment in Neonatal Piglets
Introduction: Rapid LV maturation in the neonatal period influences response to hemodynamic challenges. We recently demonstrated in a piglet model, that the neonatal heart tolerates atrial tachycardia (AT) while the infant heart fails to maintain left ventricular output (LVO). We hypothesized that augmented preload would improve LVO during AT in both the young infant (YP) and neonatal (NP) piglet.
Methods: Under anesthesia, 7 NP (1-3 days) and 7 YP (14-15 days) had a Millar high-fidelity catheter placed in the LV and pacing wire placed in the right atrium. CVP was monitored. Piglets had 60ml/kg of normal saline infused over 20 minutes. After stabilization, heart rate was increased by 10bpm increments to 300bpm. LVO was measured by echocardiography (Doppler technique). Response to preload and AT was compared from baseline for each piglet by repeated measure ANOVA, paired t-tests or Wilcoxon signed-rank test. We also compared NP and YP response to AT with normovolemic piglets from our initial study.
Results: For both NP and YP, baseline LVO increased with volume load in the hypervolemia groups (NP 271 ± 11 to 334 ± 23, p=0.007; YP 231 ± 17 to 263 ± 21 ml/kg/min, p=0.025). Even with augmented preload, YP and NP demonstrated an appropriate decrease in LVEDP and CVP with pacing. Volume loaded YP maintained LVO during AT better than euvolemic YPs (p = 0.002). Although volume-loaded NPs also maintained their LVO similarly to euvolemic NP, 4 of 7 had significant desaturation at 300bpm (baseline 99.7% vs. 300bpm 87.9%, p = 0.04), associated with a right to left shunt at the patent foramen ovale. Immediate recovery of desaturation was observed on cessation of pacing in these latter NPs.
Conclusions: Increasing intravascular volume in YPs improved tolerance to AT. Although NPs also maintained LVO, the finding of desaturation and right to left atrial shunting suggested RV intolerance to volume load during AT. These findings may be relevant to the management of neonates and young infants with AT.
Author Disclosures: E. Fortin-Pellerin: None. L.K. Hornberger: None. J.Y. Coe: None. L. Mills: None. J. Serrano-Lomelin: None. P. Cheung: None. N.S. Khoo: None.
- © 2016 by American Heart Association, Inc.