Review Question - QID 216471

A 24-year-old woman is recovering on the labor and delivery floor 2 days after a spontaneous vaginal delivery of a healthy infant at 39 weeks gestation. She suddenly complains of chest pain and dyspnea. She is otherwise healthy and has no medical problems. She has never smoked or used drugs and is a competitive runner and lifts weights daily. There were no complications during her pregnancy, and she had regular prenatal care. Her temperature is 98.7°F (37.1°C), blood pressure is 111/62 mmHg, pulse is 103/min, respirations are 25/min, and oxygen saturation is 99% on room air. Physical exam reveals an uncomfortable woman with clear breath sounds and a normal S1 and S2. An ECG is performed as seen in Figure A. Which of the following is the most likely pathophysiology of this patient’s underlying diagnosis?