Cardiovascular | EKG Basics

This paragraph introduces the importance of EKG as a diagnostic tool for clinicians. It highlights the need to understand the electrical activity of the heart, vectors, and their graphical representation on EKGs. The focus is on the basics of cardiac conduction and action potentials to correlate electrical activity with EKG readings.

This section explains the concept of a lead in EKG, focusing on Lead II. It describes the placement of positive and negative electrodes at the heart's apex and base, respectively. The electrical activity from the SA node to the AV node is discussed, highlighting how it moves towards the positive electrode to produce a positive deflection, identified as the P wave.

This part delves into the PR interval, which represents the delay at the AV node before action potentials move to the Bundle of His. It explains the significance of the PR interval in diagnosing heart blocks and emphasizes the absence of deflection during this period due to the slow conduction through the AV node.

This paragraph covers the depolarization of the interventricular septum, primarily by the left bundle branch. It introduces the Q wave, explaining that it represents septal depolarization and appears as a negative deflection due to the direction of electrical activity.

This section describes the generation of the R wave, which is a positive deflection resulting from the depolarization of the ventricles. The resultant vector, influenced by the thicker left ventricle, points downwards and slightly to the left, producing a prominent positive deflection on the EKG.

The focus here is on the S wave, indicating depolarization at the bases of the ventricles. Following this, the ST segment is described as the period when the entire ventricular myocardium is depolarized and hasn't yet repolarized, resulting in an isoelectric line.

This part explains the T wave, which represents the repolarization of the ventricles. The T wave appears as a positive deflection due to the movement of negative charges away from the positive electrode. The paragraph concludes with a summary of the different EKG components discussed.

This paragraph introduces the concept of a 12-lead EKG system, including bipolar limb leads, augmented unipolar limb leads, and chest leads. It emphasizes the importance of these leads in providing a comprehensive three-dimensional view of the heart's electrical activity.

This section details the placement and function of the three bipolar limb leads (Lead I, II, III). It explains how these leads are positioned on the right arm, left arm, and left leg, and how they provide different views of the heart's electrical activity from various angles.

This part discusses the augmented unipolar limb leads (aVR, aVL, aVF), describing how the EKG machine generates these leads by creating negative electrodes at two points and a positive electrode at another. It explains the perspectives from which each lead views the heart.

This paragraph describes the correct placement of the six chest leads (V1 to V6) on the patient's chest. It emphasizes the significance of each lead in capturing the electrical activity of different parts of the heart, including the septum, anterior wall, and left lateral wall.