570
UNIT FOUR
0
+1
–1
0
120
100
80
60
40
20
0
160
120
80
P
Q
S
T
R
P
Q
S
T
R
0.3
0.6
0.9 seconds
Heart sounds
Electrocardiogram (ECG)
Ventricular volume
Pressure changes
Ventricular volume
Ventricular pressure
Aortic pressure
Ventricular
diastole
Ventricular
diastole
Ventricular
diastole
Ventricular
systole
Ventricular
systole
Atrial
diastole
Atrial
diastole
Atrial
systole
Atrial
systole
Aortic semilunar
valve closes
Aortic
semilunar
valve
opens
AV valve
closes
Atrial pressure
AV valve opens
Volume (mL)
Millivolts
Pressure (mm Hg)
One cardiac cycle
Lubb:
AV valves close
Dupp:
Semilunar valves close
FIGURE 15.22
A graph of some of the changes that occur in the
heart during a cardiac cycle with corresponding ECG pattern and heart
sounds.
FIGURE 15.23
A prolonged QRS complex may result from damage
to the AV bundle F
bers.
S
Q
R
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