Chapter 10 Chapter 10 Chapter 11 The Normal Electrocardiogram
RhythmicalExcitation
of the Heart
RhythmicalExcitation
of the Heart
Chapter 10Chapter 10Chapter 11
The Normal Electrocardiogram
Action potentials of specialized fibersSection II-plate 11, Netter
“Normal electrocardiogram”.
Guyton, Figure 11-1. Copyright 2000, WB Saunders Company, All Rights Reserved
1 inch = 1 sec
0.2 sec
Note the “time calibration”
P-Q Interval (or P-R if Q is missing) ~ 0.16 sec
QT Interval ~ 0.35 sec
5 big blocks = 1sec
(P-Q)
Recording depolarization and repolarization waves from a cardiac
muscle fiber.
Guyton Figure 11-2. Copyright 2000, WB Saunders Company, All Rights Reserved
See Guyton –Figure 11-3
Instantaneous potentialsdeveloped
the surface of a cardiac muscle mass.
Guyton Figure 11-4. Copyright 2000, WB Saunders Company, All Rights Reserved
Flow of current in the chest around partially depolarized ventricles.
Guyton Figure 11-5. Copyright 2000, WB Saunders Company, All Rights Reserved
Guyton Figure 11-6.Copyright 2000, WB Saunders Company, All Rights Reserved
Einthoven’s Triangle
Three Biopolar Limb Leads:conventional arrangement of electrodes for recording standard ECG leads.
0.5 mV
1.2 mV
0.7 mV
Normal ECGs recorded from the three standard limb leads.
Einthoven’s law: if the electrical potentials of any two limb leads are known, the third one can be determined. The sum of the voltages in leads I and III equals Lead II.
Figure 11-7. Copyright 2000, WB Saunders Company, All Rights Reserved
5000 ohms
Connections of the body with the ECG for recording chest leads (precordial leads).
Guyton Figure 11-8. Copyright 2000, WB Saunders Company, All Rights Reserved
Normal ECGs recorded from the six standard chest leads
Guyton Figure 11-9. Copyright 2000, WB Saunders Company, All Rights Reserved
Connections of the body with the ECG for recording unipolar augmented leads.
aVR aVL
aVF
Recordings between one limb and the other two limbs.
Normal ECGs recorded from the three augmented unipolar limb leads.
Recordings between one limb and the other two limbs.
Guyton Figure 11-10. Copyright 2000, WB Saunders Company, All Rights Reserved