ECG - bums.ac.ir 45... · 2010-11-13 · ١٣ Dr. Foadoddini ECG Leads: placement of Recording...
Transcript of ECG - bums.ac.ir 45... · 2010-11-13 · ١٣ Dr. Foadoddini ECG Leads: placement of Recording...
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ECGChapt. 11,12,13
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ECG= Combination of Depol. And Repol. waves
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P‐R interval: bw
A &V excitation
Q‐T interval: V contraction
Isoelectric
قطعه
فاصله
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Biphasic record
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Current leadDepolrized
zone Polarized (Rest) zone
Importance of electrode location
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I + III = II
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Factors that change the direction of the mean electrical vector
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The Nobel Prize in Physiology or Medicine 1924
Willem Einthoven
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ECG Leads: placement of Recording Electrodes
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ECG chest lead (unipolar
leads)
–
These leads measure the electrical activity in a horizontal plane
that perpendicular to the frontal
plane
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Augmented vector
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Right to LeftBase to ApexEndocard. to Eipcard.
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Normal range-20 to +100
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Q wave
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DR
جهت انتشار امواج در بطن
جهت بردار الكتريكي
Long duration of action potentialin septum and endocardium
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Atrial
Depol. And repol.
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Plotting the Mean Electrical Axis
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Electrical Axis Deviation
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Heart position
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Hypertrophy
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Block
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Left axis deviation (Left ventricle hypertrophic)
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Right axis deviation (right ventricle hypertrophic):Pulmonary valve stenosisTetralogy
of FallotVSD
High QRS
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tetralogy of Fallot
A: Pulmonary stenosis
B: Overriding aorta
C: ventricular septal
defect (VSD)
D: Right ventricular hypertrophy
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Left axis deviation (Left bundle branch block)
Long QRS
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Right axis deviation (right bundle branch block)
Long QRS
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Short waves:
short QRS
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QRS abnormalities:
Change in voltage:Hypertrophy/InfarctionSlow conduction
Change in duration:Slow conduction/ Purkinje System Blockdestruction of cardiac muscle in various areas
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Current leadInjured zone Normal zone
Current of injury:
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Current of injury:
J pointIsoelectric line
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New collateral coronary blood flow develops
If the muscle does not die, it will continue to show an injury potential as long as the ischemia exists
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Q wave:
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T-
inversion
Slow Conduction of the Depolarization WaveShortened Depolarization in Portions of the Ventricular Muscle
Digitalin
toxicity
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1. Abnormal rhythmicity
of the pacemaker2. Shift of the pacemaker from the sinus node to another place in the heart3. Blocks at different points in the spread of the impulse through the heart4. Abnormal pathways of impulse transmission through the heart5. Spontaneous generation of spurious impulses in almost any part of the heart
Cardiac Arrhythmias
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Tachycardia>100
Bradycardia<60
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Atrioventricular
Block
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Atrial
premature beat
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A-V node premature beat
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PVC
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Paroxysmal Tachycardia
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Long QT syndrome Ventricular action potentials
QT
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Pathway around the circle is too longVelocity of conduction becomes decreasedRefractory period
of the muscle might become greatly shortened.
Re-entry
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Reentry Mechanisms
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Atrial
fibrilation
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Atrial
flutter
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Interpretation of Normal and Abnormal Cardiac Rhythm from ECG
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Sinus rhythm = 60 –
100 beats/min
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Bradycardia
= heart rate < 60 beats/min
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Tachycardia = heart rate >100 beats/min
Atrial
rate = 250-350 beats/min
Ventricular rate = 100 –
200 beats/min
Ventricular rate >250 beats/min