Fetal Cardiac Left Ventricular Hypoplasia

A 30-year-old G2P1 at 21 weeks and 5 days of gestation is referred for a detailed anomaly ultrasound after an abnormal four-chamber view is noted on routine screening. Fetal biometry is appropriate for dates, amniotic fluid is normal, and extracardiac anatomy is unremarkable. The apical four-chamber view of the fetal heart is shown. The structure marked **B** demonstrates marked disproportion with global hypocontractility and a diffusely bright echogenic endocardial lining. Which of the following best describes the ultrasound findings in this fetal cardiac abnormality?