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ECG for Interns. UCI Internal Medicine Mini-Lecture. Learning Objectives. Establish Consistent Approach to Interpreting ECGs Review Essential Cases for New Interns Provide Additional Resources for Future Learning. ECG Interpretation. What is your approach to reading an ECG? Rate Rhythm
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ECG for Interns UCI Internal Medicine Mini-Lecture
Learning Objectives • Establish Consistent Approach to Interpreting ECGs • Review Essential Cases for New Interns • Provide Additional Resources for Future Learning
ECG Interpretation What is your approach to reading an ECG? • Rate • Rhythm • Axis • Hypertrophy • Intervals • P wave • QRS complex • ST segment – T wave
Rate Square Counting: 300-150-100-75-60-50-42A Count QRS in 10 second rhythm strip x 6
Rhythm • Are P waves present? • Is there a P wave before every QRS complex and a QRS complex after every P wave? • Are the P waves and QRS complexes regular? • Is the PR interval constant?
Axis Left or right axis deviation? Look at limb leads I and aVF. • Normal: I +, aVF + • LAD: I +, aVF – • RAD: I -, aVF +
Hypertrophy LVH: S in V1 or V2 + R in V5 or V6 ≥ 35 mm. RVH: V1 R/S ratio >1 or V6 S/R ratio >1.
Intervals What is the normal PR interval? • 0.12 to 0.20 s (3 - 5 small squares). Short PR – Look for Wolff-Parkinson-White. Long PR – 1st Degree AV block What is the normal QRS? • < 0.12 s duration (3 small squares). Long QRS - look for bundle branch block, ventricular pre-excitation, ventricular pacing or ventricular tachycardia What is the normal QTc (QT/square root of RR)? • < 0.42 s. Long QTc can lead to torsades to pointes.
P Waves Evaluate the shape, height and width of P waves. • Multiple morphologies Wandering pacemaker or Multifocal atrial tachycardia • Notched (M-shaped) P-wave in I and II, > 0.12 s P-mitrale seen in severe left atrial enlargement
QRS complex Poor R Wave Progression in V1 to V6: suggests prior anterior MI Pathologic Q wave: previous MI. Q wave amplitude 25% or more of the subsequent R wave, OR > 0.04 s in width + > 2 mm in amplitude in more than one lead
Case #1 70 year old male with history of diabetes mellitus and hypertension occasionally feels lightheaded. He recently fainted while standing.
Case #2 58 year old female with no significant past medical history presents with fatigue, lightheadedness and shortness of breath.
Case #3 78 year old female with history of HTN, DM, HL, CAD admitted for syncope complains of palpitations and lightheadedness.
Case #4 67 year old male with history of diabetes, hypertension, COPD presents with chest pain.
Case #5 38 year old female with history of DM, HTN, CKD presents with 2 days of nausea and abdominal pain.
Case #6 60 year-old man with history of HTN, HL, CAD presents with nausea, shortness of breath and chest pain.
Additional Resources Websites: • http://en.ecgpedia.org/ • http://ecg.utah.edu • http://ecg.bidmc.harvard.edu/maven/ Apps: • ECG Guide by QxMD (iPad and iPhone) • ECG Interpret (iPhone) Books: • 12-Lead ECG: The Art of Interpretation, Tomas Garcia (perhaps the best book on ECGs with detailed explanations and physiology.) • Arrhythmia Recognition, Tomas Garcia
Summary • Always keep a consistent approach. • Do not rely upon machine reads. • Practice makes perfect.