Teachable Moments in ECG: The Physiology Behind the Pattern

Introduction

The electrocardiograph (ECG) has stood as a very important tool in the diagnosis of cardiovascular diseases and other important medical conditions, and as a fundamental of clinical practice.[1 ] ECG interpretation is an important skill acquired by physicians, internists, cardiologists and other subspecialists through years of training and experience, and most of all, actual cases and electrocardiographs deciphered, dissected and diligently discussed. Through the years, it has evolved into a teaching tool where the teacher and pupil connect and engage in stimulating discussions about various aspects related to the case and to cardiovascular medicine. These “teachable moments” in ECG are priceless treasures that can serve as opportunities for learning and improving one’s knowledge and skill in interpretation. The ECG analysis and interpretation of heart blocks can be one great “teachable moment”. Heart blocks can present in different levels of severity which can appear as different patterns on ECG tracing. While quick recognition of this condition relies on identification of ECG patterns, a deeper understanding of the electrical basis and electrophysiologic mechanisms of the pattern is imperative and will reduce the likelihood of error.[2]

Case Description:

A 91-year-old female patient who was admitted for pneumonia presented with bradycardia and the following electrocardiogram (ECG) tracing (Figure 1). The patient had stable vital signs with blood pressure 110/70 mmHg, heart rate 50 bpm, respiratory rate 16 cpm.