Abstract 17543: The Chicken or the Eggs? Examining the Causal Relationship Between the Development of Atrioventricular Valve Regurgitation and Ventricular Dysfunction in Patients With Functionally Single-Ventricle Physiology

Introduction: Development of atrioventricular valve regurgitation (AVVR) with or without ventricular dysfunction (VD) often occurs during the first 6 months of life and has a significant impact on outcomes for single-ventricle patients. Yet, it is not well known whether AVVR causes VD or vice versa. Thus, we sought to identify the timing and causal relationship between AVVR and VD. Methods: Among 156 consecutive single-ventricle patients who had staged palliation (2005- 2012), 28 who had AVV repair at the time of stage II (n=24, 86%) or inter-stage (n=4, 14%) were reviewed. Diagnosis included HLHS in 17 (61%) patients, tricuspid atresia in 2 (7%), and others in 9 (32%). Ventricular morphology was left-dominant in 6 (21%) patients and right-dominant in 22 (79%). AVV morphology included mitral in 6 (21%) patients, tricuspid in 18 (64%), and common in 4 (14%). Serial echocardiograms were reviewed to identify the timing of development of AVVR and/or VD. Results: After stage I palliation, ventricular end-diastolic dimension (VEDD) z-score significantly increased from 4.01 to 5.69 (p<0.01) AVVR (Figure). By the time of stage II palliation, VEDD further increased and subsequent AVV annular dilation occurred, resulting in 23 patients with significant AVVR. None of the patients, however, had significant VD before stage II palliation/AVV repair, but 9 patients developed significant VD after AVV repair. Conclusions: Ventricular dilation occurred immediately after stage I palliation and continued until stage II palliation. Secondary annular dilation occurred inter-stage and this further triggered the development of AVVR. Tangible ventricular dysfunction was not seen before AVV repair, however, important ventricular dysfunction was unmasked after volume unloading surgery. Heart failure management and early intervention to significant AVVR may reduce the incidence of ventricular dysfunction following AVV repair.