K 305

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K 305 16 May 03
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Cardiac Excitation Cardiac Action Potential Ionic
Basis of Ventricular AP Initiation of
Excitation Propagation of Excitation EKG
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Information garnered from EKG

• anatomical orientation of heart
• chamber sizes
• arrhythmias and conduction problems
• ischemia - degree and location
• previous MIs

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(No Transcript)
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Action Potentials in Myocardium
Superior Vena Cava
SA Node
Atrium
AV Node
Purkinje
Tricuspid Valve
Mitral Valve
Ventricle
R
T
ECG
P
Q
S
PR
QRS
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• EKG conventions
• currents move from positive to negative
• currents moving towards positive (or recording)
  electrode produce an upward deflection on EKG
  chart

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EKG Leads

• Bipolar
• Standard limb leads
• Unipolar leads        
• augmented   aVR right arm     aVL left
  arm     aVF foot
• precordial  6 chest leads across intercostal
  spaces (V1-V6)

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Standard bipolar limb leads (Figures 22-33,
22-34) bipolar (remember the polarity)
Einthoven's triangle lead 1 LA    RA -lead
2 LL    RA-lead 3 LL    LA- Anatomic
orientation and dimensions of chambers Remember
I III II
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(No Transcript)
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(No Transcript)
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Information garnered from EKG

• anatomical orientation of heart
• chamber sizes
• arrhythmias and conduction problems
• ischemia - degree and location
• previous MIs

13
(No Transcript)
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(No Transcript)
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Information garnered from EKG

• anatomical orientation of heart
• chamber sizes
• arrhythmias and conduction problems
• ischemia - degree and location
• previous MIs

16
arrhythmias and conduction problems

• Bundle branch block
• Long QT syndrome

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arrhythmias and conduction problems

• Bundle branch block
• Long QT syndrome

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(No Transcript)
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Action Potentials in Myocardium
Superior Vena Cava
SA Node
Atrium
AV Node
Purkinje
Tricuspid Valve
Mitral Valve
Ventricle
R
T
ECG
P
Q
S
PR
QRS
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arrhythmias and conduction problems

• Bundle branch block
• Long QT syndrome

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Long QT syndrome - QT gt 0.5s
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HERG Long QT mutations
T474I
G628S
S1
S2
S3
S5
S6
V822M
NH2
COOH
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(No Transcript)
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Boy with congenital Long QT syndrome that becomes
torsades de pointes.
Q
T
QT interval gt 0.6 s