Page 212 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

F. Wilson chest leads (unipolar)
V 9
V 8
V 1 –V 6
V 7

V 6
II
V r6
R V 5
V r5
V r4 V 4
1 2 V r3 V 1 V 3
View from above V 2 Electrocardiogram (ECG)
G. Determination of largest mean QRS vector (QRS axis) using ECG leads I–III
1 “Vertical” 2 “Intermediate” 3 “Horizontal” (left axis)

II III II III II III QRS
I I I Plate 8.7
QRS axis
α=90° QRS α=50° α=0°
(α= +60° to +90°) (α=+30° to +60°) (α= +30° to –30°)
+ +
I I
– –
+ +
II II
– –
+ +
III III
– –
H. Electrical axis of the heart I. ECG changes in coronary infarction
Infarction R ECG
4
Left axis –30° P
deviation
Q T 2
R 1
Left axis P
0° Stage 2
T
Q (days to wks later)
R 5
Right axis
deviation Inter- 3
mediate +30° P
axis
Right Vertical Q S T
axis axis Stage 1
+120° +60° (few hrs to days later) Stage 3 199
(months to yrs later)
+90° Normal
range (after Netter)
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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