12 Lead ECG Basics: Interpretation and Application

LEARNING OBJECTIVES

Upon completion of the module, the participant should be able to: 

1. Identify the coronary blood vessels that supply the heart.
2. Identify components of the hearts electrical conduction system.
3. Recognize and explain the role of electrolytes in cardiac function.
4. Recognize and explain normal and abnormal ECG waveforms.
5. Recognize indicators of ischemia, injury, and infarction during acute coronary syndromes.
6. Interpret electrocardiogram (ECG) findings on a 12 Lead ECG.
7. Identify appropriate treatment considerations for patients with acute coronary syndromes.

CONTENTS FOR THIS MODULE

THE HEART AS A VITAL PUMP

• Anatomy of the Heart
• Low pressure pump
• High pressure pump

CORONARY VESSELS

• Right coronary artery (RCA)
• Left coronary artery (LCA)
• Left anterior descending artery (LAD)
• Left circumflex artery (LCX)

ELECTRICAL CONDUCTION OF THE HEART

• Sinoatrial (SA) node
• Internodal pathways
• Atrioventricular (AV) node
• Bundle of His.
• Left and Right Bundle Branches
• Perkinje fibers
• Ventricles

CHEMICAL BALANCE AND ELECTROLYTES

• Adenosine triphosphate (ATP) as energy source
• Sodium (Na+)
• Potassium (K+)
• Calcium (Ca+)
• Magnesium (Mg++)

THE ELECTROCARDIOGRAM (ECG)

• Lead Placement
• Limb Leads
• Augmented Leads
• Precordial Leads
• Additional ECG Leads

ECG Paper and Measurements

• Size and design of electrocardiogram paper

Waveforms and Complexes

• Isoelectric line
• P wave
• PR-interval
• Q wave
• R wave
• S Wave
• T wave
• U wave

Normal ECG Waveform Measurements

• Measurements
• Amplitude
• Deflection
• Duration

INTERPRETING A 12 LEAD ECG

• Rate
• Rhythm
• Axis Deviation
• Bundle Branch Blocks
• Sgarbossa Criteria – A Tool to Evaluate STEMI Mimics

Ischemia, Injury, and Infarction

• Ischemia
• Injury
• Infarction

Acute Coronary Syndromes

• ST segment elevation myocardial infarction (STEMI)
• Non-ST segment elevation myocardial infarction (NSTEMI)
• Unstable angina (coronary spasm)
• Angina (relieved with relaxation and/or nitroglycerine administration)

REGIONS OF THE HEART

• Septal
• Anterior
• Lateral
• Inferior
• Posterior
• Indicators of distress

Reciprocal changes

• T wave inversion (downward)
• ST-segment deviations or elevation
• Q waves may evolve as wide and deep
• Reciprocal changes (cardiac area opposite of the ST elevation shows ST depression)

Hypertrophy

• Atrial
• Ventricular

ECG ABNORMAILITY CONSIDERATIONS -ECG Findings and Possible Clues for Causes

• Early Repolarization
• Pericarditis
• Left Ventricular Hypertrophy
• Pacemakers
• Potassium
• Calcium
• Digoxin toxicity
• Wellens’ Syndrome
• Brugada Syndrome

Assessment Considerations

• Assessment

Treatment Considerations

• Treatment considerations
• Medications

Assess Your Knowledge

• 12 lead ECG assessment
• 12 Lead knowledge
• Coronary circulation
• Cardiac electrical systems

 References:

1. How the Heart Works www.webmd.com
2. Understanding how your heart functions www.nhsinform.scot
3. What are coronary arteries? my.clevelandclinic.org.
4. Heart Conduction System (Cardiac Conduction) my.clevelandclinic.org.
5. Anatomy and Function of the Heart’s Electrical System www.hopkinsmedicine.org
6. Cardiac conduction system medlineplus.gov
7. How potassium, magnesium, sodium and calcium imbalances can lead to serious heart complications. https://pharmaceutical-journal.com
8. Life-Threatening Electrolyte Abnormalities https://www.ahajournals.org
9. Electrocardiogram (ECG or EKG) https://www.mayoclinic.org
10. Heart Disease and Electrocardiograms https://www.webmd.com
11. Electrocardiogram (ECG or EKG) https://www.heart.org
12. Electrocardiogram (EKG) https://my.clevelandclinic.org
13. ECG Lead Placement Guide https://www.numed.co.uk
14. Recommendations for the Standardization and Interpretation of the Electrocardiogram https://www.ahajournals.org
15. The 12-Lead ECG in Acute Coronary Syndromes
16. The Importance of the 15-lead Versus 12-lead ECG Recordings in the Diagnosis and Treatment of Right Ventricle and Left Ventricle Posterior and Lateral Wall Acute Myocardial Infarctions. https://www.ncbi.nlm.nih.gov
17. Prehospital 12-lead ST-segment monitoring improves the early diagnosis of acute coronary syndrome https://www.ncbi.nlm.nih.gov
18. Acute coronary syndrome https://www.mayoclinic.org
19. Acute Coronary Syndrome https://www.heart.org
20. Heart https://my.clevelandclinic.org
21. Picture of the Heart https://www.webmd.com
22. What is an abnormal EKG? https://www.healthline.com
23. Definition of Early Repolarization https://www.ahajournals.org
24. ECG Diagnosis: Acute Pericarditis https://www.ncbi.nlm.nih.gov
25. Wellens Syndrome https://www.ncbi.nlm.nih.gov
26. Brugada Syndrome https://emedicine.medscape.com
27. Left ventricular hypertrophy https://www.mayoclinic.org
28. ECG Features demonstrating the Digoxin Effect https://litfl.com
29. Digitalis https://www.sciencedirect.com
30. ECG Basics: Determining Rate https://www.ncbi.nlm.nih.gov
31. Sgarbossa criteria for acute myocardial infarction. https://www.ncbi.nlm.nih.gov
32. Walraven, G. Basic Arrhythmias. Pearson Higher Ed, 2014.
33. Phalen, T., and B. Aehlert. The 12-Lead ECG in Acute Coronary Syndromes. Mosby Incorporated, 2005.
34. Phalen, T., and B. J. Aehlert. The 12-Lead ECG in Acute Coronary Syndromes. Mosby/JEMS, 2018