Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Unauthorized reproduction of this article is prohibited Pediatric Critical Care Medicine www.pccmjournal.org 1 Objectives: To investigate the effect of right ventricular stunning on interventricular relationships in newborn piglets and to determine the effect of three commonly used inotropic treatment strategies. Design: Randomized, placebo-controlled animal study. Setting: Aarhus University Hospital, animal laboratory. Subjects: Twenty-eight newborn (4-d old) farm-bred piglets. Interventions: Acute right ventricular failure was induced by 10 cycles of alternating 3 minutes of ischemia and reperfusion of the right coronary artery. After right ventricular failure was induced, treatment with epinephrine + milrinone, dopamine + milrinone, dobutamine, or control (saline) was initiated, and the animals were observed for 180 minutes. Measurements and Main Results: Right and left ventricular systolic and diastolic variables were measured using pressure- volume loops recorded by conductance catheters. Arterial and central venous pressures were recorded, and cardiac index was determined by placing a flow probe around the pulmonary artery. Whole-body perfusion was evaluated by measuring pH and lactate in arterial blood samples. Induction of right ventricu- lar stunning resulted in decreased ejection fraction (51% ± 4% vs 40% ± 12%, p = 0.0004); caused an interventricular sep- tum deviation, decreased mean arterial pressure (49 ± 10 mm Hg vs 43 ± 11 mm Hg, p = 0.03), and increased blood lactate (1.85 ± 0.6 mM vs 5.79 ± 3.16 mM, p < 0.00001); and led to a decrease in blood pH (7.37 ± 0.08 vs 7.23 ± 0.13, p < 0.00001). A mortality rate greater than 50% was observed in the control group. All inotropic interventions increased contractility signifi- cantly in both the left and right ventricle. The effect of dobu- tamine on right ventricular failure decreased after 30 minutes and was indistinguishable from the control group after 3 hours. Dobutamine-treated animals had lower perfusion pressures and blood pH compared with epinephrine + milrinone and dopa- mine + milrinone groups. Conclusions: In newborn piglets, dobutamine had a nonsustained effect on right ventricular failure, resulting in decreased contrac- tility and impaired perfusion compared with both dopamine and epinephrine administered in combination with milrinone. (Pediatr Crit Care Med 2014; XX:00–00) Key Words: adrenaline; animal model; cardiovascular agents; catecholamine; dobutamine; dopamine; heart failure; milrinone; myocardial stunning; neonate; newborn; nonsustained; right heart; right heart failure; right ventricle; stunning L ow cardiac output (CO) is observed in approximately 25% of all children undergoing cardiac surgery for con- genital heart disease (1, 2) and may be related to left or right ventricular (RV) failure. RV failure is more common in the pediatric population than in the adult population and is associ- ated with systemic hypotension and decreased coronary perfu- sion, which may further aggravate ventricular performance. Indications for the use of epinephrine, dopamine, dobu- tamine, and milrinone are well described for the treatment of acute heart failure in adults. However, evidence for the choice of therapy in acute heart failure in children, espe- cially neonates, is limited (3). A comparison of the effect of Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000202 1 Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark. 3 Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark. 4 The Heart Centre, Division of Cardiology, The Hospital for Sick Children, Toronto, ON, Canada. 5 Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark. Supported, in part, by The Danish Council for Independent Research, Medical Sciences; Danish Children Heart Foundation; Foreningen Østifterne; and Department of Clinical Medicine, Aarhus University. The authors have disclosed that they do not have any potential conflicts of interest. Address requests for reprints to: Hanne B. Ravn, DMSc, Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Skejby, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. E-mail: hbr@ki.au.dk For information regarding this article, E-mail: janus.hyldebrandt@ki.au.dk Inotropic Therapy for Right Ventricular Failure in Newborn Piglets: Effect on Contractility, Hemodynamics, and Interventricular Interaction Janus A. Hyldebrandt, MD 1,2 ; Christian A. Frederiksen, MD 1 ; Johan Heiberg, MD 3 ; Susani Rothmann, MD 3 ; Andrew N. Redington, FRCP 4 ; Michael R. Schmidt, PhD 5 ; Hanne B. Ravn, DMSc 1