The diagnostic ECG: Anatomical-clinical correlation

In this episode of the Loomis-Alvarez Medical Video Series, we present an anatomical correlation of the most frequently used diagnostic test of heart function, the electrocardiogram (ECG). From the film industry to textbook publishers and apparel designers, ECG tracings are the hallmark of medical care. While patterns can be learned and even become readily recognizable, for many learning the ECG, correlating that oscillating line on an ICU monitor with the four-chambered heart once seen and held in the anatomy lab can be a formidable challenge. But, it is that correlation that can lead to a deeper, more nuanced understanding of the ECG. Heart disease being a leading cause of morbidity and mortality globally underscores the importance of this deeper understanding. The electrical rhythm captured by the ECG orchestrates the mechanical response of the heart muscle, propelling blood throughout the body to meet metabolic demands. When abnormalities in the heart's structure impact this vital electrical activity leading to mechanical irregularities in the pumping process, we can see that structural abnormalities are reflected in the ECG. Correlation of the heart’s physical structure with its physiologic function and electrical image captured from anterior, left, right, and inferior leads, is crucial for healthcare practitioners. To better understand normal electrical activity during the cardiac cycle we present the live capturing of an ECG. With the approximate location of a patient’s heart and conduction system drawn on their chest, leads are placed and the tracings are captured. Each lead’s tracing is correlated with illustrations of the heart’s chambers and conductive system within a skeletal model. Arrows are overlaid to show the primary direction of the electrical impulse towards, away from, or at right angles to the different leads. This basic understanding of ECG tracings can provide a solid foundation on which to build a more sophisticated and ongoing understanding of this profoundly useful diagnostic tool.