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Bioreology and basic
gemodinamic.
The Heart
and the Cardiovascular System
(2) Cardiac Mechanics.
(1) Cardiac electrophysiology.
The Heart: two pumps in series: (1) Pulmonary circulation: propels
blood through lungs for exchange of O2 and CO2. (2) Systemic
circulation: propels blood to all other tissues or organs of body.
Anatomy of the Heart
Longitudinal cross section
Basic Hemodynamics
Basic Hemodynamics
Types of flow
Flow of fluid in a cylindrical tube may be laminar of
turbulent.
Laminar flow: flow in lamina, fluid particles do not
move in radial or circumferential direction.
In Laminar flow the pressure drop (DP) is proportional
to flow.
Poiseuille’s law
10
7.2
8.4
6.0
Log Resistance
ΔP 8η L
R
 4
F πr
4.8
3.6
2.4
1.2
1
1
5
0.
25 125 625 125 625 125 063
0.
0
0.
03 015 078 039
0.
.
0
0
0
0.
0.
0.
Residual Radius (%)
Effect of stenosis degree on resistance
9.6
Types of flow
Turbulent flow: irregular flow of fluid elements.
Rapid radial and circumferential mixing.
In turbulent flow the pressure drop is approximately
proportional to square of flow.
Pressure and Volume in the Circulation
Pressure is pulsatile in
the arteries but steady
in the capillaries and
veins.
Pressure falls along
the circuit with the
greatest fall across
arterioles.
Volume is greatest in
the venous system. At
any time most of the
blood is in veins
The Cardiac Cycle
Ventricular
Ejection
Phase
Atrial
Systole
Isovolumetric
Contraction
Pressure (mm Hg)
120
100
Ventricular
Filling
Isovolumetric
Relaxation
Semi-Lunar
Valve Closes
Semi-Lunar
Valve Opens
Arterial Pressure
80
60
40
AV Valve
Closes
10
AV Valve
Opens
Ventricular Pressure
0
R
S
Q
Atrial
Systole
Approx. Time
0
Electrocardiogram
T
P
0.1
Ventricular
Systole
0.2
0.3
0.4
Diastole
0.5
Arterial Pressure Curve
0.6
0.7
0.8
The cardiac cycle
Relationship of myocardial
resting sarcomer length (end-diastolic volume) to developed
force (peak systolic ventricular pressure) during ventricular
contraction in the intact dog heart
Pressure-volume loop
Pressure-volume loop
C
D
B
A
ESV
Pressure-volume loop for changing preload
Compliance:
Definition:
C=
DV
DP
In regards to aortic mechanics DV or Dva is stroke volume
(SV) and DP or DPa is pulse pressure (PP, or Ps-Pd).
For aorta
DPa =
DVa
Ca
Aortic Pressure Waveform
120
Systolic
mm Hg
Dicrotic Notch
100
Mean Pressure
80
Pulse
Pressure
Diastolic
Systole
Diastole