??? ???? ??? ???(Electrocardiogram) ???

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??? ??????? ???(Electrocardiogram)
???

• ???        ??????????
• ??? ??????????
• 1.??????????
• 2.???????????????????????
• 3.????????????????

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• Questions
• Why ECG could be served for the diagnosis of some
  diseases?
• How does ECG work?
• What is ECG? What is normal ECG?
• A real case with chest pain
• diagnosis

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A. Basic knowledge of ECG

• 1. Depolarization and repolarization
• Single myocardial cell
• A muscle strip
• 2. Vector and resultant vector

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3. Pacing and conducting system of the heart

• Sinus node? Internodal tracts? AV node ?
• right bundle branch (RBB)
  Purkinje fibers
• Bundle of His
• 
  anterior fascicle
• left bundle branch (LBB)
  Purkinje fibers
• 
  posterior fascicle

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4. Lead system

• ?    Limb leads Standard leads I, II, III
• ?    Limb leads aVR, aVL, aVF
• Hexaxial system
• Chest leads V1, V2, V3, V4, V5,
• V6, V7, V8, V9

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B. Normal ECG

• P wave
• PR interval
• QRS complex
• ST segment
• T wave
• QT interval
• U wave

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1.    Measurement of ECG waves and intervals

•  ? ECG paper
• ? Measuring heart rate (HR) 60/R-R (bpm)
• regular or irregular rhythm
• ? Amplitude of waves or segment P, QRS,
• S-T, T, U
• ? Width or duration of waves P, QRS, T,
  U
• ? Duration of intervals P-R, Q-T
• ? Shape of waves P, QRS, T

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2. Mean QRS axis

• l normal cardiac axis range from -30?90?
• l significant left deviation -30??-90?
• L right deviation 90??180?
• L significant right deviation 180??-90?
• 3. Clockwise and counterclockwise rotation
• l    Clockwise rotation
• ? Counterclockwise rotation

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4. Normal ECG

• (1) P wave atrial depolarization
• l        Amplitude ? 0.20 mv
• l        Duration ? 0.11 sec
• l        Positive in I, II, aVF, V4-V6
• Negative in aVR
• (2) PR interval the time for intraatrial,
• AV nodal, and His-Purkinje conduction,
• Duration 0.12 0.20 sec

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(3) QRS complex ventricular depolarization

• l  The width 0.06?0.10 sec, ? 0.11 sec.
• l From V1 to V6, the R waves gets bigger and
  bigger, the S waves gets smaller and smaller.
• l   R/S lt l in V1, but R/S gt l in V5
• l   R in V5 and V6 lt 2.5 mv, R in V1 lt 1.0 mv
• l   R in aVR lt 0.5 mv,
• l   R in aVL lt 1.2 mv and R in aVF lt 2.0 mv
• l   R in I lt 1.5 mv
• l   Q lt 0.04 sec in width, lt 1/4 R in the same
  lead.

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• (4) ST segment it reflects Phase 2 of the action
  potential.
• l ST elevation lt 0.3 mV in V1?V2 0.5 in V3,
• lt 0.10 mV in V4 ? V6
• l ST depression lt 0.05 mV in any leads
• (5) T wave repolarization of ventricles
• It is upright in all the unipolar leads
  except
• aVR, and occasionally V1.
• T wave gt 1/10 R in the same lead, maybe
• lt 1.2?1.5 mV in the precordial leads

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• (6) QT interval the duration of depolarization
  and repolarizaion of ventricles.
• The normal range is 0.32?0.44 sec.
• (7) U wave the wave following the T wave and is
  usually very small.
• Its cause is not completely understood.
• Elevated U wave low K in plasma

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C. Summary

• Why ECG could be served for the diagnosis of
• some diseases?
• How does ECG work?
• What is ECG? What is normal ECG?
• 1. Basic knowledge of ECG(electrocardiogram)
• Depolarization and repolarization
• Vector and resultant vector
• Pacing and conducting system of the heart
  
• Lead system (Limb leads) I, II, III, aVR,
  aVL,
• aVF, (Chest leads) V1, V2, V3, V4, V5

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• 2. Normal ECG P wave, QRS complex, T wave,
• U wave, PR interval, QT interval, ST segment,
  
• R-R (P-P)
• Mean QRS axis
• Clockwise and counterclockwise rotation
• Normal value and shape
• l Amplitude of waves or segment P, QRS, T, U
• and S-T
• l Width or duration of waves P, QRS, T, U
• l Duration of intervals P-R, Q-T
• l Shape of waves QRS, T
• Clinical significances of abnormal ECG

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TEST in classroom

• Please translate the following words into
  Chinese

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PRACTICE

• Make an ECG by yourself first.
• Read and measure your ECG with correct way and
  steps.
• Is your ECG normal or abnormal?
• Keep your ECG for memory. It is the first time as
  a doctor to make ECG and diagnosis!
• Good beginning is the half of success!