Challenges With Left Ventricular Functional Parameters: The Pediatric Heart Network Normal Echocardiogram Database.

•3215 normal echo studies were collected from healthy children ≤18 years of age.•17% had abnormal blinded core lab calculated values for LV SF <25% and/or EF <50%.•Those with abnormal SF/EF were significantly younger and smaller.•Repeat expert measurements of LV size showed good interobserver reproducibility.•Calculated LV functional indices, however, revealed significant variability.