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Temporary Postoperative Left Ventricular Apex Pacing Does Not Improve Hemodynamics

Friday, October 19, 2012
Room 275-277 (Morial Convention Center)
Benton Ng, Benjamin Reinking, Dianne L. Atkins, MD, FAAP, Ian Law and Nicholas Von Bergen, Pediatric Cardiology, University of Iowa, Iowa City, IA

Purpose:  Arrhythmias after congenital heart surgery are common and often treated with pacing via temporary epicardial pacing wires placed on the atrium and ventricle.  However, the optimal location for a single site of ventricular pacing is unknown, as pacing may result in ventricular dyssynchrony and dysfunction.  It has been postulated that temporary pacing at the left ventricular (LV) apex may be preferred to avoid ventricular dyssynchrony.  Despite significant advances in congenital cardiac surgery, there have been limited prospective trials evaluating alterations in hemodynamics by pacing at varying single ventricular sites. We compared the hemodynamic effects of two temporary right ventricular pacing sites and left ventricular apical pacing in pediatric postoperative cardiac patients. We hypothesized that pacing from the left ventricular apex would result in improved hemodynamics.   

Methods: Inclusion criteria included patients up to 17 years of age at the time of surgery with a systemic left ventricle and two ventricle anatomy.  In addition to atrial pacing wires, temporary ventricular pacing wires were placed on 2 of the following 3 sites in a random fashion a) right ventricular (RV) free wall, b) RV mid septum, and c) LV apex. Postoperatively, arterial blood pressure and echocardiographic data (shortening fraction, ejection fraction (EF), LV outflow tract (LVOT) diameter, LVOT velocity time integral, tissue Doppler imaging, 3D EF, and 3D synchrony measures) were obtained in sinus rhythm and following atrioventricular synchronous pacing at each ventricular site for 5 minutes.  Pacing was stopped and patients were excluded if adverse events occurred during pacing.  

Results: The age range of study participants (n = 31) was 22 days - 13 years (median = 0.6 years, 63% male). The underlying heart disease included: ventricular septal defect, atrial septal defect, LVOT obstruction, transposition of the great arteries, Tetralogy of Fallot, pulmonary stenosis, atrioventricular canal, aortopulmonary window, pulmonary atresia with intact ventricular septum, and total anomalous pulmonary venous return.  For evaluation of pacing site effect on blood pressure, the systolic blood pressure (SBP) obtained during pacing was normalized to that obtained during sinus rhythm.  The normalized SBP while pacing at the RV free wall, RV mid septum, and LV apex were 1.01, 1.04, and 1.04 respectively (p = NS). No difference was observed in diastolic blood pressure, EF, EF by 3D echocardiogram, or measurements of left ventricular synchrony for LV pacing compared to either RV site. No patient experienced an adverse event during the pacing maneuvers

Conclusion:  Our data demonstrate that there is no hemodynamic benefit to LV apical pacing in the post-operative period compared to RV free wall or RV mid septal pacing.