Mesocardia With Upward and Leftward Apex Secondary to a Large Hiatal Hernia: A Case Report.

We report the case of an 82-year-old woman with a known history of hiatal hernia who presented with intermittent chest discomfort and exertional dyspnea. Electrocardiography revealed sinus rhythm with axis deviation and a prominent R wave in lead aVR, initially raising concern for limb lead reversal, conduction abnormality, or myocardial ischemia. Chest radiography demonstrated a retrocardiac air-fluid level, and computed tomography (CT) confirmed a large type III hiatal hernia displacing the heart centrally, with the apex directed upward and leftward. No congenital structural cardiac abnormalities were identified. The patient was managed conservatively. This case highlights how a large hiatal hernia can alter cardiac orientation and produce atypical electrocardiographic findings. It underscores the importance of correlating ECG abnormalities with imaging studies to avoid misdiagnosis and unnecessary interventions.