Abstract 12063: Exercise Stress Echocardiography Exposes Reduced Left Ventricular Contractile Reserve and Abnormalities of Biventricular Function in Children with Repaired Tetralogy of Fallot
Introduction: Early hallmarks of ventricular compromise are needed in patients with repaired tetralogy of Fallot (TOF) so that the evolving pathophysiology might be monitored from its earliest stages.
Hypothesis: Exercise echocardiography will reveal abnormalities unapparent at rest and permit noninvasive characterization of the LV force frequency relationship.
Methods: A prospective study including 29 children with TOF and 44 controls. M-mode and tissue Doppler data was obtained for the LV, RV and right ventricular outflow tract (RVOT) with images recorded at rest and during peak bicycle exercise. LV myocardial acceleration during isovolumic contraction (LV IVA) was measured 10bpm heart rate intervals during exercise and force-frequency curves were constructed. Children with TOF also underwent magnetic resonance imaging (MRI), a cardiopulmonary exercise test and measurement of neurohormonal markers.
Results: TOF children had RV dilatation (mean RVEDVi=153mls/m2 SD=37.3) but normal ventricular function (LVEF mean=59.3% SD=6.2, RVEF mean=50.2% SD=8.5) and no evidence of neurohormonal activation. Resting echocardiography detected abnormalities of RV but not LV function (table). Exercise echocardiography revealed abnormalities of LV contractility (table) and a highly abnormal force-frequency relationship (figure) p<0.0001. There was a weak relationship between peak exercise LV IVA and peak VO2, r=0.45 p<0.03.
Conclusion: Children with TOF have abnormal RV contractile properties at rest. During exercise stress they develop evidence of LV dysfunction and disruption of LV force-frequency relations, which may be related to impaired exercise performance.
- © 2011 by American Heart Association, Inc.