This case study follows a group of fictitious medical students during their obstetrics rotation as they meet “Brittany,” a woman who is 35-weeks pregnant and experiencing tachycardia and shortness of breath. The medical students review the basics of electrocardiogram (ECG) testing and various types of arrhythmia and eventually narrow down the problem to either atrioventricular nodal reentry tachycardia (AVNRT) or Wolff-Parkinson-White (WPW) syndrome. Students who complete the four sections of this case study will learn the components of an ECG and what they represent (Part I), interpret Brittany’s ECG results and identify how they differ from a typical ECG (Part II), choose the best diagnosis for Brittany based on her symptoms and test results (Part III), and suggest a proper treatment for the pregnant patient (Part IV). The case is appropriate for an undergraduate human anatomy and physiology course for allied health students, an introductory biology course, and possibly a comparative physiology course.