Understanding the Electrocardiogram

TABLE  OF  CONTENTS.

PREFACE

UDEMY  COURSES IN ECG

THE 12 LEAD ELECTROCARDIOGRAM

Basics & Interpretation.

1. HISTORY OF ELECTROCARDIOGRAPHY

2. CONDUCTION SYSTEM-ECG PAPER- ECG LEADS

THE CARDIAC CONDUCTION SYSTEM

P-QRS-T WAVES.

THE ECG PAPER

ECG RATE CALCULATION

ECG LEADS

HOW TO AVOID ARTEFACTS WHILE RECORDING THE ECG.

3. BASIC CARDIAC ELECTROPHYSIOLOGY.  THE ACTION POTENTIAL

THE AP OF THE NORMAL MYOCARDIAL CELL.

AP OF THE PACEMAKER CELL.

4. THE NORMAL  ECG

THE P-QRS-T WAVES

THE INTERVALS & SEGMENTS.

5. ATRIAL ENLARGEMENT & VENTRICULAR HYPERTROPHY

ATRIAL ENLARGEMENT

VENTRICULAR HYPERTROPHY

6. ELECTRICAL AXIS OF THE HEART -THE QRS AXIS

7. ISCHEMIC  HEART  DISEASE

PATHOPHYSIOLOGY.

LOCATION OF THE INFARCT AREA.

POSTERIOR WALL MYOCARDIAL INFARCTION. (PWMI).

PROGRESSIVE CHANGES OF Acute MI

RIGHT VENTRICULAR MYOCARDIAL INFARCTION. (RVMI)

NON-ST ELEVATION MYOCARDIAL INFARCTION.

8. MISCELLANEOUS CONDITIONS

ACUTE PULMONARY EMBOLISM

DIGOXIN  EFFECT & TOXICITY.

HYPERKALEMIA

HYPOKALEMIA

PERICARDITIS

EARLY REPOLARIZATION SYNDROME

HYPERCALCEMIA

HYPOCALCEMIA

CHRONIC OBSTRUCTIVE PULMONARY DISEASE

PRE-EXCITATION SYNDROMES

LOWN GANONG LEVINE SYNDROME

HYPOTHERMIA

DEXTROCARDIA

BRUGADA SIGN  / BRUGADA SYNDROME

WELLENS’ SYNDROME

CARDIAC  ARRHYTHMIAS

PART 1.

Disorders of Impulse Formation.

9. INTRODUCTION TO ARRHYTHMIAS

10.ABNORMALITIES OF SINUS RHYTHM

SINUS ARRHYTHMIA.

SINUS BRADYCARDIA.

SINUS TACHYCARDIA.

11. ATRIAL ARRHYTHMIAS

ATRIAL PREMATURE BEATS.

SUPRAVENTRICULAR TACHYCARDIA

ATRIOVENTRICULAR NODAL RE-ENTRY TACHYCARDIA

ATRIOVENTRICULAR RE-ENTRANT TACHYCARDIA

ATRIAL TACHYCARDIA (ECTOPIC ATRIAL TACHYCARDIA)

MULTIFOCAL ATRIAL TACHYCARDIA

12. ATRIAL FLUTTER – ATRIAL FIBRILLATION.

ATRIAL FLUTTER

ATRIAL FIBRILLATION

13. VENTRICULAR ARRHYTHMIAS

VENTRICULAR PREMATURE COMPLEXES

VENTRICULAR TACHYCARDIA

VENTRICULAR FLUTTER

VENTRICULAR FIBRILLATION

POLYMORPHIC VENTRICULAR TACHYCARDIA

TORSADES DE POINTES

14.  ESCAPE BEATS, ESCAPE RHYTHMS

JUNCTIONAL ESCAPE BEAT

VENTRICULAR ESCAPE BEAT

JUNCTIONAL RHYTHM – (Idiojunctional Rhythm)

ACCELERATED JUNCTIONAL RHYTHM

VENTRICULAR RHYTHM (Idioventricular Rhythm)

ACCELERATED VENTRICULAR RHYTHM

CARDIAC  ARRHYTHMIAS

PART 2.

Disorders of Impulse Conduction.

15. BUNDLE BRANCH BLOCK

THE CONDUCTION SYSTEM

RIGHT BUNDLE BRANCH BLOCK (RBBB).

LEFT BUNDLE BRANCH BLOCK  (LBBB).

BUNDLE BRANCH BLOCK WITH AMI.

16. FASCICULAR BLOCKS

LEFT  ANTERIOR  FASCICULAR  ....................................BLOCK

LEFT  POSTERIOR  FASCICULAR  ...................................BLOCK

BIFASCICULAR BLOCK

MASQUERADING BUNDLE BRANCH BLOCK.

TRI FASCICULAR BLOCK

17. ATRIOVENTRICULAR BLOCKS

FIRST DEGREE  ATRIOVENTRICULAR BLOCK

SECOND DEGREE ATRIOVENTRICULAR  BLOCK

THIRD DEGREE AV BLOCK - COMPLETE HEART BLOCK

18. MISCELLANEOUS  ARRHYTHMIAS

SINOATRIAL BLOCK

INTRAVENTRICULAR CONDUCTION DEFECT

ECHO BEAT (Reciprocal Beat)

PARASYSTOLE

19. CLINICAL – ECG CORRELATIONS

12 LEAD ECG – Clinical Correlation.

ARRHYTHMIAS – Clinical Correlation.

BIBLIOGRAPHY

About the Author

Books by the Author

Acknowledgements

PREFACE

This is a pocket book for students of Electrocardiography. It  was written as a chapter for a book planned to be published by the Indian Medical Association in Calicut. But due to some technical difficulties, the book never saw the light of day and I was left with the article which I had named ‘Understanding the ECG’.

A year later, on the request of a few friends and students of mine, I decided to print this as a small booklet of 44 pages for private circulation among my interns, residents, and nurses in the Cardiology ICU in my institution. In the year 2012, the Calicut Forum of Internal Medicine (CALFIM) offered to get the booklet printed for distribution to their members, other physicians in the profession, interns, residents and post graduate students in Medicine. Thus, the first edition was born and  distributed free for private circulation only.

My interest in teaching ECG had been inculcated by my mentor Prof. K. Sugathan who was my teacher and later senior colleague in the department of Cardiology in the Medical college, Calicut, Kerala. He had been trained in Cardiology under Padmabhushan Prof. Sujoy B Roy from the prestigious All India Institute of Medical Sciences in New Delhi and was awarded the DM degree in 1971. I was posted in the department of Cardiology as an intern, fresh with an undergraduate degree in Medicine and bubbling with enthusiasm and the eagerness to learn. Prof. Sugathan was instrumental in indoctrinating me into this passion of interpreting the ECG. This was in the year 1973 when ECGs and Chest X rays were almost the only diagnostic procedures available in Cardiology. Cardiac catheterization had not yet reached our institution. 

Another of my mentors during that period in the department of General Medicine was Prof. P.C. Easaw who was instrumental in guiding me in this endeavor during my internship days. Between them, they taught me all that I know and ushered me into the intricate and fascinating world of ECGs.

This passion of mine stimulated my mentor, Prof. Sugathan to teach me all the complexities of interpreting the ECG and this forged in  me a lifelong interest in learning and teaching ECG interpretation. He taught me the tips and tricks in ECG interpretation and some ‘rule of thumb’ shortcuts.  Even after becoming a member of the teaching faculty in the Calicut Medical College, I continued to learn and teach ECG to my interns and residents and was sought after in medical circles for my ECG classes.

This book is a humble attempt on my part to share this knowledge with my students and the medical fraternity. After retiring from my profession, I decided to continue my ‘ECG teaching Odyssey’ and prepared three video courses on ECG interpretation for the platform the Udemy learning platform for the benefit of students and doctors world over.

‘What the mind does not know, the eyes do not see’ is a dictum which is true in the interpretation of ECG.

Subsequently, I decided to leave a legacy of my work to the initiates in this skill of interpreting ECGs by updating my previous booklet. This book is the result of that attempt.

Having time on my side, I decided to update my original booklet ‘Understanding the ECG’ with more ECG tracings, diagrams, and content in line with my ECG courses on Udemy. Thus, was born this book which is a companion to the  three courses on Udemy namely, Learn the Basics of ECG Interpretation, Cardiac Arrhythmias -Part 1 and Cardiac Arrhythmias – Part 2.

This book is not intended as a complete text book of Electrocardiographic interpretation. Intricate arrhythmias and complicated annotations have been avoided. This books aims to be a handy guide for learning the basics of ECG interpretation only. It is a pocket book for the zealous clinicians and nurses in the ICU. It aims to provide a quick bedside reference for the diagnosis of ECG abnormalities for students, interns, and nurses in the intensive care units. For more detailed information, the student is referred to the Bibliography given at the end of the book.

Throughout the book, "Takeaway Points" have been included which emphasize certain important essentials to be committed to memory. A special chapter at the end of the book is included under  ‘Clinical-ECG Correlations’.

I have included the ECG tracings which I had collected from my internship days in 1973 till my retirement over a span of 45 years and some of them are rare specimens. Some ECGs were sent to me by my protégés and colleagues. To substantiate my explanations, I have included some simple hand-drawn diagrams in the book. 

I have to pay my respects to my teachers Late Prof. K.N. Ravindran, Prof. Ashokan Nambiar and Dr. Kunhali in addition to the numerous colleagues who have been a source of encouragement, help and inspiration to me in all my ventures.

The management of Baby Memorial Hospital where I had been working for over 24 years prior to my retirement as a Senior Consultant Cardiologist and lately as the Chief of Medical Services always gave me  its  unstinted support and help in my professional and teaching career. They had my original book reprinted for private circulation in 2018.

With these few words, I humbly submit this book to my students.

Dr. K. V. Sahasranam. MD, DM (Cardiology)

UDEMY  COURSES IN ECG

The Udemy Courses are available with Video content, Power point presentations and Resources in their platform.  The courses extend to over 8 hours totally with detailed explanations being provided in each module. Plenty of diagrams and ECG tracings have been included in these modules for the benefit of the student.

The courses are as under:

LEARN THE BASICS OF 12-LEAD ECG INTERPRETATION

CARDIAC ARRHYTHMIAS  PART  -1

CARDIAC ARRHYTHMIAS  PART  -2

THE 12 LEAD ELECTROCARDIOGRAM

Basics & Interpretation.

1. 

HISTORY OF ELECTROCARDIOGRAPHY

The Electrocardiogram (ECG) revolutionized the diagnosis of heart diseases in the early twentieth century. It was Augustus Waller who in 1887 first recorded and demonstrated the ECG of the human heart. He was a British physiologist in London. But at that time, he did not recognize the importance of this discovery. Willem Einthoven, who was a witness to this demonstration by Waller was inspired by this and took up the challenge to develop this further.

Thus, it was Willem Einthoven (1860-1927), a Dutch physiologist, who took this idea forward and recorded the ECG using a string galvanometer. It was he who named it the ‘Electrocardiogram’. He designated the deflections ‘P-QRS-T’ and published his findings in 1902. His ECG tracing was of fairly good quality. In 1905 he presented cases of atrial and ventricular hypertrophy, ventricular bigeminy, ventricular premature beats and identified the ‘U’ wave in the ECG.  The same year, he transmitted the ECG via telephone  and recorded it 1500 meters away.

Willem Einthoven  (1860-1927)

Einthoven’s electrocardiograph which recorded the first ECG weighed 600 lbs.

In 1924, Einthoven was awarded the Nobel prize in Physiology and Medicine "for the discovery of the mechanism of the electrocardiogram". His recording had only three leads – the Triaxial Bipolar Limb Leads. Einthoven conceived the famous Einthoven’s Equilateral  Triangle with leads I, II and III as its sides. This facilitates electrical axis calculation.

In 1934, Dr Frank N Wilson of the University of Michigan developed the concept of the ‘central terminal’ and the Unipolar chest leads and named them V1-V6. (V stood for Vector) In 1938  he