A brief review: history to understand fundamentals of electrocardiography

Abstract

The last decade of the 19th century witnessed the rise of a new era in which physicians used technology along with classical history taking and physical examination for the diagnosis of heart disease. The introduction of chest x-rays and the electrocardiograph (electrocardiogram) provided objective information about the structure and function of the heart. In the first half of the 20th century, a number of innovative individuals set in motion a fascinating sequence of discoveries and inventions that led to the 12-lead electrocardiogram, as we know it now. Electrocardiography, nowadays, is an essential part of the initial evaluation for patients presenting with cardiac complaints. As a first line diagnostic tool, health care providers at different levels of training and expertise frequently find it imperative to interpret electrocardiograms. It is likely that an understanding of the electrical basis of electrocardiograms would reduce the likelihood of error. An understanding of the disorders behind electrocardiographic phenomena could reduce the need for memorizing what may seem to be an endless list of patterns. In this article, we will review the important steps in the evolution of electrocardiogram. As is the case in most human endeavors, an understanding of history enables one to deal effectively with the present.

Keywords: electrocardiogram; electrocardiography; history.

Fig. 1

Timeline of clinically pertinent landmarks in the development of EKG, acknowledging the important efforts of other scientists in this process.

Fig. 2

First human electrocardiogram recorded by Augustus D. Waller of St Mary's Medical School showing simultaneous electrometer and cardiograph tracings showing an electrical activity preceding every heart beat. From Ref. (6).

Fig. 3

Two superimposed ECGs are shown. Uncorrected curve is labeled ABCD. This tracing was made with refined Lippmann capillary electrometer. The other curve was mathematically corrected by Einthoven to allow for inertia and friction in the capillary tube. He chose the letters PQRST for the corrected curve based on mathematical tradition of labeling successive point on a curve. From Ref. (8).

Fig. 4

Old string galvanometer electrocardiograph showing the big machine with the patient rinsing his extremities in the cylindrical electrodes filled with electrolyte solution.

Fig. 5

Wilson's precordial leads.

Fig. 6

(A) Bipolar limb leads covering the frontal plane in 60° intervals. (B) The addition of the unipolar leads provided a more detailed coverage with 30° intervals.