A 29-year-old primigravida woman presented to the outpatient obstetric clinic for a routine antenatal checkup. Cardiovascular system examination revealed a systolic murmur in the left upper parasternal region, which was initially thought to be a physiological murmur of pregnancy. There was no history of dyspnea, chest pain, palpitation, or lower limb swelling. Her vital parameters were within normal limits. The 12-lead electrocardiogram (ECG) is presented in the Figure.