4.28M
Категория: Медицина
Похожие презентации:

# ECG for Interns

## 1. ECG for Interns

UCI Internal Medicine Mini-Lecture

## 2. Learning Objectives

• Basics of EKG
• Establish Consistent Approach to Interpreting ECGs
• Rate, rhythm, axis, identifying ischemia
• Review Essential Cases for New Interns
• Provide Additional Resources for Future Learning

## 4. Basics of EKG: Einthoven’s Triangle and Vectors

+AVR
Why is lead II often so
important?
->you can see the heart’s
depolarization vector is in
the same axis as lead II!
->this means that in normal
conduction, the QRS
should be upright in lead II
+AVL
+AVF

## 5. ECG Interpretation

•Rate
•Rhythm
•Axis
•Hypertrophy
•Intervals
•P wave
•QRS complex
•ST segment – T wave

## 6. Rate

Square Counting: 300-150-100-75-60-50-42A
Count QRS in 10 second rhythm strip x 6 use this method to
determine rate when rhythm is irregular (e.g., atrial fibrillation)

## 7. Rhythm Look at the rhythm strip below and answer the questions

Are P waves present?
• yes
Is there a P wave before every QRS complex and a QRS complex after
every P wave?
• yes
Are the P waves and QRS complexes regular?
• yes
Is the PR interval constant?
• yes
Yes to all these
questions, so this is
normal sinus rhythm!

## 8. Axis

•Axis is the general flow of electricity as it passes through
the heart
Look at the main direction of the QRS complex in leads I and AVF
I
AVF
Axis
+
+
normal
+
-
-
+

## 9. QRS Duration

• Normal QRS is < 120 ms
• Prolonged QRS duration (>120ms) is seen in bundle
branch blocks (BBB).
• This is a result of abnormal conduction through the
bundle branches or fascicles in the electrical conduction
system
• Different criteria for left and right bundle branch blocks
but know the general morphology of each.

## 10. Left and right bundle branch blocks

Left BBB –
• Dominant S wave in V1 (‘W’-shaped)
• Broad, notched (‘M’-shaped) R wave in V6
Right BBB –
• Tall R wave in V1 (‘M’-shaped)
• Wide, slurred S wave (‘W’-shaped) in V6

## 11. 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
- Q wave > 0.04 s in width + > 2 mm in amplitude in more than one lead

## 12. Hypertrophy

LVH: 2 commonly used criteria (use either)
1. Sokolow criteria:
S in V1 or V2 + R in V5 or V6 ≥ 35 mm.
2. Cornell criteria:
S in V3 + R in aVL > 28 mm (men)
S in V3 + R in aVL > 20 mm (women)
RVH:
V1 R/S ratio >1
OR
V6 S/R ratio >1

## 13. 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.

## 14. P Waves

•Left atrial enlargement (P mitrale) = wide, bifid P wave: >0.12s in
lead II or biphasic P in lead V1 with largely negative terminal portion
•Right atrial enlargement (P pulmonale) = peaked P: amplitude
>2.5mm in inferior leads (II, III, avF) or >1.5mm in V1, V2
•If multiple morphologies Wandering pacemaker or
Multifocal atrial tachycardia (common in COPD)

## 15. ST segment and MI

ST elevation may indicate STEMI if the following are met:
• At least 1 mm (0.1 mV) elevation in the limb leads (I, II, III, AVL, AVR)
• At least 2 mm elevation in the precordial leads (V1-V6)
• Elevation must be in at least 2 anatomically contiguous leads (see upcoming slides on
ST depression may indicate NSTEMI if the following are met:
• Downsloping ST depression ≥ 0.5 mm
• Must be in at least 2 anatomically contiguous leads

LET’S DO SOME
PRACTICE CASES

## 20. Case #1

70 year old male with history of diabetes mellitus and
recently fainted while standing.

## 22. Case #2

58 year old female with no significant past medical
history presents with fatigue, lightheadedness and
shortness of breath.

## 24. Case #3

78 year old female with history of HTN, DM, HL,

## 26. Case #4

67 year old male with history of diabetes,
hypertension, COPD presents with chest pain.

## 28. Case #5

60 year-old man with history of HTN, HL, CAD
presents with nausea, shortness of breath and chest
pain.

## 29. Case #5 ECG

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

## 31. Summary

• Learned the basics of EKG
• Learned how to have a consistent approach to EKGs
• Reviewed essential cases for new interns
• Equipped with resources for continued learning