This document provides an overview of ECG essentials and interpretation. It lists six essential lists related to ECG findings and covers evaluating rhythms, causes of abnormalities, treatment approaches, and the importance of comparison to prior ECGs. Computer analysis can help with accurate measurements and calculations but may miss subtle findings, so provider interpretation is still needed.

1. ECG Essentials Steven J. Sager, MPAS, PA-C PAC5229 - Electrocardiography

2. Learning Objectives Upon satisfactory completion of the course, and in conjunction with textbooks, lecture handouts, and any recommended internet Web Sites, the student will be able to: Recognize the components of the following lists: List #1 – Causes of regular, narrow-complex tachycardia List #2 – Causes of regular, wide-complex tachycardia List #3 – Common causes of prolonged QT interval List #4 – Common causes of ST segment depression List #5 – Common causes of a tall R wave in lead V 1 List #6 – Causes of anterior ST segment depression in the setting of acute inferior infarct

3. Learning Objectives Discuss the pathophysiology of dysrhythmias List the factors which determine if a patient is hemodynamically stable List the advantages of 12-lead vs. single lead ECGs Explain the importance of ECG comparisons Describe the benefits and limitations of ECG interpretation by computer analysis Recognize common dysrhythmias

4. Six Essential Lists List #1 – Causes of regular, narrow-complex tachycardia List #2 – Causes of regular, wide-complex tachycardia List #3 – Common causes of prolonged QT interval List #4 – Common causes of ST segment depression List #5 – Common causes of a tall R wave in lead V 1 List #6 – Causes of anterior ST segment depression in the setting of acute inferior infarct

5. Evaluating regular, narrow-complex tachycardia P = P waves? Q = Q RS wide or narrow? R = R egular rhythm? S = P waves & QRS complexes “ S ingle”?

6. Hemodynamically stable? Symptomatic? Chest pain Dyspnea/SOB Altered mental status Hypotension Shock Heart failure Pulmonary edema AMI

7. Causes of regular, narrow-complex tachycardia

11. Treatment of regular, narrow-complex tachycardia Vagal Maneuver May transiently slow the ventricular response Will either convert PSVT to sinus rhythm or have no affect at all Types: Carotid sinus massage Valsalva Facial submersion in ice Gagging Ocular pressure Digital rectal massage Squatting and bearing down Adenosine “ chemical Valsalva” almost immediate slowing of ventricular response

12. Causes of regular, wide-complex tachycardia (WCT)

13. Treatment of regular, WCT Hemodynamically unstable Cardiovert (synchronized) Hemodynamically stable Determine etiology Review prior tracings If in doubt, treat for VT Procainamide

14. QT prolongation Prolongation of the QT interval on the ECG is the major marker for Long QT Syndrome Long QT syndrome is one of the causes of sudden death in adolescents and young adults “ sudden death” = unexpected death that occurs in a someone who is apparently healthy Long QT Syndrome is thought to be the cause when sudden death occurs from ventricular fibrillation

15. QT prolongation It most frequently occurs during sporting events and is usually attributed to a sudden, unpredictable disturbance in the rhythm of the heart. the symptoms can occur during less strenuous activities and even on awakening from sleep may become apparent when a young person with fainting or secondary seizures has an ECG as part of their evaluation it is especially important to look for the syndrome when the fainting or seizures are excercise-related

16. Causes of QT prolongation Ischemia Infarction Drugs Type IA and type III antiarrhythmic agents TCAs Phenothiazines

17. Causes of QT prolongation Electrolyte deficiencies hypokalemia hypomagnesia hypocalcemia Catastrophic CNS event CVA intracerebral hemorrhage seizures

19. Common causes of ST segment depression Ischemia - symmetric “ Strain” - asymmetric Digitalis effect – scooped or strain pattern Hypokalemia Hypomagnesia

20. ST-segment depression

22. Common causes of a tall R wave in lead V 1 Wolff-Parkinson-White (WPW) syndrome Right bundle branch block (RBBB) Right ventricular hypertrophy (RVH) Acute infero-postero-lateral infarction Hypertrophic cardiomyopathy Muscular dystrophy Dextrocardia Normal variant

23. Differentiate the causes of a tall R wave in lead V 1 Causes QRS ECG ∆’s W-P-W Widened Delta waves Short PR interval RBBB Widened rSR ´ in V 1 Wide terminal S wave in I and V 6 RVH Normal RAD R ventricular strain Infarct Normal Changes in inferior leads Positive “mirror test”

24. 60 y.o. ♂ with history of heart disease. 72 y.o. ♀ with history of palpitations. 28 y.o. ♂ with no medical problems or heart disease. 66 y.o. ♂ 2ppd smoker with history of COPD. 48 y.o. ♂ with new onset chest pain.

25. Causes of anterior ST segment depression in the setting of acute inferior infarct Reciprocal changes Concomitant anterior ischemia Posterior infarction Mirror test Combination of above ∆ ’ s (ST depression) c ommon in: V 1 , V 2 , and V 3

26. Why 12-lead vs. 1-lead? 12-lead provides more information improves arrhythmia interpretation CXR? ABG?

27. 60 y.o. ♀ c/o rapid heart beat. Denies CP. No meds. B/P = 140/90mmHg Rate? P? Q? R? S?

28. 50 y.o. ♂ with CAD c/o rapid heart beat. Denies CP. B/P = 160/100mmHg Rate? P? Q? R? S?

29. 60 y.o. ♂ with COPD c/o wheezing & mild dyspnea. Hx of rapid heart beats. B/P = 130/80mmHg.

30. 60y.o. ♂ c/o “palpitations”

31. Comparing Tracings Find as many as possible Evaluate previous tracings valid regardless of age and interval Evaluate new tracing Compare the two most recent tracings systematically move from one lead to the next start at I and proceed through V 6 Comment on ANY and ALL differences !

32. Important Comparison Points to Consider Review all available tracings request old charts look for “patterns” Lead placement variables may alter axis, wave amplitude/morphology, etc. Request serial ECGs when appropriate angina evolving MI interval?

33. Benefits of Computer Analyses Save time Accurate calculations of: heart rate intervals axis Provide legible interpretations May suggest additional findings write your interpretation first, then compare Educational improve provider accuracy

34. Are Computer Analyses Accurate? Sometimes only as good as their programming! reliably recognize sinus/normal tracings Most accurate in computing values Routinely miss subtle infarctions Tend to overinterpret Should be used to enhance the provider’s interpretation provide a good “ second opinion”

35. Reviewing a Computer Analysis √ √ Agree as corrected. S. J. Sager, PA-C Intervals/durations in milliseconds Date & time are CRITICAL! Includes patient identification

36. Thought for the day! Our background and circumstances may have influenced who we are , but only we are responsible for who we become !

38. Mirror test