The Natural History of Atrioventricular Valve Regurgitation Throughout Fetal Life in Patients with Atrioventricular Canal Defects.

Atrioventricular valve regurgitation (AVVR) influences morbidity and mortality in the atrioventricular canal defect (AVC). Fetal cardiac structures are subject to hemodynamic changes, as well as growth and maturation during gestation, which may alter the degree of AVVR and affect prognosis. We sought to investigate the frequency of change in degree of AVVR documented by fetal echocardiography (echo) between different periods of gestational age. Subjects with AVC seen in the Fetal Heart Program between January 2008 and September 2010 were identified. Degree of AVVR was assessed by color Doppler imaging and categorized as Grade 0 (no AVVR), Grade 1 (hemodynamically insignificant AVVR = trivial or mild), and Grade 2 (hemodynamically important AVVR = ≥moderate). Levels of AVVR between periods were compared. Forty-three fetuses were analyzed. Overall, 60% had no change, 14% had a decrease, and 26% had an increase in AVVR grade. Two fetuses progressed from Grade 0 or 1 to Grade 2, while one fetus decreased from Grade 2 to Grade 0. Trisomy 21 and heterotaxy syndrome were not risk factors for AVVR progression. Transitional and incomplete canal defects may be more susceptible to AVVR progression. Sixty percent of fetuses with AVC will not exhibit progression of AVVR between the second and third trimesters of gestation. In those who exhibit change, it is most often within a hemodynamically insignificant range between none and mild regurgitation (Grades 0 and 1). These findings have implications for the counseling, follow-up, and delivery plans of the fetus with AVC defect.