Download CVS 4 Dr Kelly

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5
Isovolumic ventricular
relaxation: as ventricles
relax, pressure in ventricles
falls, blood flows back into
cups of semilunar valves
and snaps them closed. Ventricular ejection:
4
as ventricular pressure
rises and exceeds
pressure in the arteries,
the semilunar valves
open and blood is
ejected. 1
Late diastole: both sets of
chambers are relaxed and
ventricles fill passively.
2
Atrial systole: atrial contraction
forces a small amount of
additional blood into ventricles.
3
Isovolumic ventricular
contraction: first phase of
ventricular contraction pushes
AV valves closed but does not
create enough pressure to open
semilunar valves.
1
EDV = end diastolic volume = volume of blood in ventricle at end of diastole
ESV = end systolic volume = volume of blood in ventricle at end of systole
SV = stroke volume = volume of blood ejected from heart each cycle
SV = EDV - ESV
130 mL – 70 mL = 60 mL in this case. Usually 70-90mL
Ejection fraction: % EDV ejected with each stroke (approx. 65%)
A good index of ventricular function
KEY
Left ventricular pressure (mm Hg)
EDV = End-diastolic volume
ESV = End-systolic volume
Stroke volume
120
D
ESV
80
C
One
cardiac
cycle
40
EDV
B
A
0
100
65
Left ventricular volume (mL)
135
2
0
Electrocardiogram
(ECG)
Time (msec)
200
300
400
100
P
QRS
complex
500
600
700
800
QRS
complex
Cardiac cycle
T P
120
Pressure
(mm Hg)
90
Aorta
Dicrotic
notch
Left
ventricular
pressure
60
Left atrial
30
pressure
Heart
sounds
Left
ventricular
volume
(mL)
Atrial systole
S1
S2
135
65
Isovolumic
ventricular
contraction
Atrial Ventricular
systole
systole
Ventricular
systole
Ventricular
diastole
Early
ventricular
diastole
Atrial
systole
Late
ventricular
diastole
Atrial
systole
3