2-心脏力学

(1) Starling curve Methodology and terms
•Preload, Initial length, resting (passive) tension, length-
passive tension curve
•Afterload, isometric contraction, active tension, length-
active tension curve
在心肌
长度－静息张力曲线
长度上限
长度－主动张力曲线
升支陡
无降支
Rat ventricle
Bovine atrium
Rat ventricle
Bovine atrium
rat ventricle
the atrium of
large animals
(4) Cardiac length-active tension curve
在心肌
长度－静息张力曲线
长度上限
Double overlap
长度－主动张力曲线
升支陡
无降支
在骨骼肌
降支
水平段
升支•Double overlap
3.0–3.1·μm
▲2.6–2.7·μm
○2.2–2.3·μm
Data from skinned frog ventricular myocytes. As (6) Two phases of response to a change of initial length
The law of Laplace P= 2T/R
In diastole, P T R
In systole, R P
Contractile element Viscoelastic Passive property time-dependent state-dependent
volume
pressure
V 0
ESPVR
end-systolic pressure-volume relationship
a
d V ES
(3) Ventricular elastance E(t)=
V(t)-V 0
Emax
Changing preload
Changing afterload（aortic pressure）
pressure
volume
epinephrine
control
(6) The work and oxygen consumption •Linear with PVA but not with the pattern to
contraction
•Linear with PVA but not with stroke work •Stroke volume, less important determination of the energy cost during contraction Linear with PVA but not with the pattern to contraction and stroke work
Inotropic state change the intercept but not slope
PVA mmHg ml/beat 100g LV
Internal work (10）Cardiac efficiency
•Total energy consumption of the heart Q=氧热价X心肌耗氧量
Q=氧热价X动静脉氧差X 冠脉血流量•心脏机械效率＝
有用功
总耗能
5%－20%
Determinants of the heart efficiency
•Pressure
•Volume of ventricle
•Heart rate。