Turner syndrome is a rare chromosomal abnormality in women that is caused by a partial or complete loss of one X chromosome and is often associated with a spectrum of congenital cardiac abnormalities, including cardiac shunts.  A 27-year-old woman with Turner syndrome was also found to have right ventricular dilation, partial anomalous pulmonary venous return, and possible atrial septal defect. She was scheduled for elective surgical repair. However, a preoperative review of diagnostic imaging raised the specter of Eisenmenger syndrome, a highly morbid condition defined by secondary, severe pulmonary hypertension where shunt correction may potentiate acute hemodynamic collapse. Multimodality imaging and invasive hemodynamics were used to comprehensively evaluate shunt physiology and guide surgical correction.