Principles Of EKG Interpretation

INTRODUCTION TO

PRINCIPLES OF EKG INTERPRETATION

The purpose of this manual is to present a method for acquiring skill in interpretation of the electrocardiogram. It should be used as a learning tool and not as a reference text. The manual is designed to carry the totally uninitiated student as well as the practicing physician to an understanding of spatial electrocardiography.

Among those who should be able to read EKGs include residents, interns, medical students, nurses in the emergency department and ICU/CCU, nurse practitioners, nurse anesthetists, physician assistants and personnel involved in pre-hospital care.

Robert P. Grant, M.D. who taught it between 1947 and 1950 at Emory University School of Medicine, Atlanta, Georgia, developed spatial analysis of the electrocardiogram.

A technique of spatial analysis is presented in a systematic fashion in Chapter 2. It was taken from Spatial Analysis of the Electrocardiogram, Chapter 1, by Irwin Hoffman, M.D. Dr. Hoffman was my mentor in electrocardiography from 1970 to 1974 during my residency in medicine and fellowship in cardiology at Cedars-Sinai Medical Center, Los Angeles, California.

In order to stimulate the imagination of the reader, pertinent illustrations and concepts from the following publications have been utilized in the manual.

1. Clinical Electrocardiography, The Spatial Vector Approach, Robert P. Grant, M.D., McGraw-Hill Book Company, 1957

2. Introduction to Electrocardiography, 2nd edition, J. Willis Hurst & Robert J. Myerburg, McGraw-Hill Book Company, 1973

3.Diagnostic Electrocardiography & Vectorcardiography, H. Harold Friedman, M.D., FACP, FACC, McGraw-Hill Book Company, 1971

4. Clinical Vectorcardiography, 2nd edition, Te-Chuan Chow, M.D., Robert A. Helm, M.D., & Samuel Kaplan, M.D., Grune & Stratton, 1974

5. The Hemiblocks, Mauricio B. Rosenbaum, M.D., Marcelo V. Elizari, M.D., Julio O. Lazzari, M.D., Tampa Tracings, 1970

6. The Disorders of Cardiac Rhythm, Leo Schamroth, Blackwell Scientific Publications, 1971

7. The Cardiac Rhythms, Raymond E. Phillips, M.D., F.A.C.P. & Mary K. Feeney, R.N., B.S.N., W.B. Saunders Company, 1973

8. Electrocardiography, Third Edition, E. Grey Dimond, M.D., Paul Schlesinger, M.D., Rafael L. Luna, M.D., The Corinth Press, 1961

9. Structure And Function Of The Cardiovascular System, Second Edition, Robert F. Rushmer, M.D., W.B. Saunders Company, 1976

10. Practical Electrocardiography, Fourth Edition, Henry J.L. Marriott, M.D., The Williams & Wilkins Co., 1968 

Pattern interpretation of the electrocardiogram is the most commonly employed method in clinical practice. Most clinicians that use the pattern method get excellent results. However, there are those who feel that spatial analysis should be made available to anyone desiring to enhance his or her understanding of the differences in electrical activity between normal and diseased hearts.

Both pattern and spatial vector approaches have advantages and disadvantages associated with their use. Inherent with pattern recognition is the large number of configurations that must be committed to memory. Spatial analysis unfortunately often carries the stigma of “vector-phobia”. 

An article by J.W. Hurst, M.D. (co-author of Introduction to Electrocardiography, 2nd edition) entitled, “Methods Used to Interpret the 12-Lead Electrocardiogram: Pattern Memorization versus the Use of Vector Concepts”, appeared in Clinical Cardiology, Vol. 23, No. 1: p. 4-13. In the article, Dr. Hurst indicates his support of spatial analysis of the electrocardiogram. The summary of the article is reprinted below.

“This article extols the value of using Grant’s approach to the interpretation of electrocardiograms (ECGs). The essay includes a discussion on how people learn and emphasizes the difference in memorizing information, thinking, and learning. Simply stated, the brains of most people are not designed to memorize countless numbers of ECG patterns. Accordingly, the essay supports the view that a method of interpretation must be used, and the reader is encouraged to use basic principles of electrocardiography, including vector concepts, to interpret each ECG.” 

Spatial analysis virtually eliminates the need to memorize literally hundreds of patterns. A relatively small number of spatial vector profiles describe most of the electrocardiographic abnormalities commonly encountered in clinical practice.

Pattern interpretation may be likened to attempting to identify an individual from a verbal description. This is often very difficult. The spatial vector method, on the other hand, is similar to viewing a photograph or “mug shot” of a person often resulting in an almost immediate recognition. Word descriptions are analogous to electrocardiographic patterns, whereas, photographs are comparable to spatial “profiles”.

The following is reprinted