Download Ventricular pressure

Cardiovascular
Structure
& Function
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Cardiovascular system:
The heart
Arteries
Veins
Capillaries
Lymphatic vessels
Weighting of the heart ceremony: Ancient Egyptians
William Harvey and Blood Flow
April 1, 1578 – June 3, 1657
Introduction
• The most basic functions of the cardiovascular system are:
• To deliver oxygen and nutrients to body tissues
• To remove waste
• To regulate temperature
Circulatory system
Circulatory system
1. Left ventricle
2. Aorta
3. Arterial system
4. Vena cava
5. Right atrium
6. Right ventricle
7. Pulmonary artery
8. Lungs
9. Pulmonary veins
10. Left atrium
1. Left ventricle
Heart valves
Pulmonary
Aortic
P
T
M
A
Mitral
Tricuspid
Systolic and Diastolic phases
Diastolic phase =
Ventricular filling
Systolic phase =
Ventricular ejection
Cardiac cycle
Systole
Diastole
Animation: http://library.med.utah.edu/kw/pharm/hyper_heart1.html
LV volume (mL)
Pressure (mmHg)
Aortic and Ventricular Pressures
PA
100
50
PLV
0
160
120
80
Ejection
Normal pressures
Unit = mmHg [1 mmHg = 133 Pa]
Left Atrium
Left ventricle
Aorta
Right Atrium
Right ventricle
Pulmonary artery
2-11
90-140 / 5-12
90-140 / 60-90
0-8
15-30 / 0-8
15-30 / 4-12
Intra-cardiac and arterial pressures
Hypertension
Hypertension is defined as an abnormal
increase in arterial pressure
Hypertension results in an
increase in ventricular work
and ventricular hypertrophy
Pressure and Flow
mmHg
Systolic Pressure
100
Diastolic Pressure
50
0
0
0.5
1
1.5
0
0.5
1
time in s
1.5
mL/s
400
200
0
Classification of arterial pressure (> 18 years)
Systolic pressure = maximal pressure
Diastolic pressure = minimal pressure
CATEGORY
SYSTOLIC (mmHg)
DIASTOLIC (mmHg)
Normal
< 130
< 85
Normal ++
130-139
85-89
STAGE 1 (Mild)
140-159
90-99
STAGE 2 (Moderate)
160-179
100-109
STAGE 3 (Severe)
180-209
110-119
STAGE 4 (Very Severe)
>209
>119
Hypertension
A very low pressure should also by examined by a Doctor.
3
100
2
50
1
Ventricular Volume (mL)
0
0
160
1
1
4
0.2
0.4
0.6
0.8
2
1
Ventricular pressure (mmHg)
Pressure (mmHg)
Ventricular pressure-volume curves
140
Stroke
volume
120
120
100
3
2
80
60
Stroke
volume
40
20
1
4
0
60
80
100 120 140 160
Ventricular volume (mL)
100
3
80
0
0.2
4
0.4
Time (s)
0.6
0.8
1.
2.
3.
4.
Isovolumetric contraction
Ventricular ejection
Isovolumetric relaxation
Ventricular filling
Ventricular Pressure (mmHg)
Ventricular work
120
100
80
1J
60
40
20
0
60
80
100 120 140 160
Ventricular volume (mL)
P : Ventricular pressure
V : Ventricular volume
Effect of systemic hypertension
200
200
Normal pressures
100
100
1J
0
0
0.5
1
1.5
0
80
120
160
200
200
Severe hypertension
100
100
0
0
0
0.5
1
1.5
1.5 J
80
120
160
Ventricular work as a f(preload,afterload)
Factors influencing flow and pressure
Mean pressure (MAP) and pulsed pressure (PP)
SP (systolic pressure)
PP
MAP (mean pressure)
DP (diastolic pressure)
MAP 
2/3 DP + 1/3 SP
PP = SP  DP
Resistance and compliance
Resistance : R  MAP / CO
MAP : mean arterial pressure
CO : cardiac output
Compliance : C  SV / PP
SV : stroke volume
PP : pulse pressure
Normal conditions (120/80 mmHg) :
R = 1.1 mmHg.s/mL
C = 2.0 mL/mmHg
Severe hypertension (190/115 mmHg) :
R = 1.7 mmHg.s/mL
C = 0.8 mL/mmHg
Resistance and compliance
Normal flow rate : SV = 70 mL, CO = 5L/min
Resistance : R  MAP / CO
R increases  MAP increases
Compliance : C  SV / PP
C decreases  PP increases
MAP
mmHg
100
PP
50
0
0
0.5
1
1.5
Hypertension and aortic pressure
Normal (120 / 80)
200
R = 1.1 mmHg.s / mL
C = 2.0 mL / mmHg
MAP
100
95
PP
0
0
0.5
1
1.5
Severe hypertension (190 / 115)
200
MAP
140
PP
100
0
MAP = 95 mmHg
PP = 40 mmHg
0
0.5
1
R = 1.7 mmHg.s / mL
C = 0.8 mL / mmHg
MAP = 140 mmHg
PP = 75 mmHg
1.5
Arterial Pressure
Flow, resistance and compliance of the arterial system
are significant determinants of arterial pressure
Another parameter that can determine arterial
pressure is wave reflection in the arterial system.
Arterial pressure and wave reflection
dorsalis
pedis
Femoral a
artery
aorta
Arterial pressure and wave reflection
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Incident wave
Reflected wave
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Heart Sounds
Heart Sounds
Two heart sounds can be distinguished: S1 and S2.
S1 is synchronized with early systolic phase.
S2 is synchronized with the end of systolic phase.
The frequencies are between 10 and 500 Hz with low intensity
1st stethoscope
• 1816 Laennec was examining
a young female patient
• He was embarrassed to place
his ear to her chest
• Rolled up 24 sheets of paper,
placed one end to his ear and
the other end to the woman’s
chest
• Discovered that the sounds
were also louder and clearer
Examples of stethoscopes
In 1819, the French doctor
René Laënnec invented
the stethoscope.
Examples of stethoscopes
En 1851, Dr. Marsh
developed the 1st
commercial model.
Pathological heart sounds
Several pathologies induce turbulence in the flow in the
cardiovascular system.
High frequencies in the turbulent flow generate audible sounds.
Aortic stenosis
Animation: http://www.healthcentral.com/heart-disease/valves/
Aortic valve
Normal vs Stenosed
Aortic stenosis : different origins
Congenital
Rhumatismal
Calcification
Aortic stenosis
The most common valvulopathy in industrial countries.
Prevalence 1 to 2 % in people > 65 years old.
Valvular surgeries in Canada (1996-1997)
Aortic stenosis
Carabello et al. NEJM, 1997
Symptoms
• Angina pectoris
• Syncope
• Intolerance to exercise
Investigation of the severity of aortic stenoses
- Gorlin Equation
- Energy loss coefficient
Valve replacement
•Biological valves :
Xeno-valves : pericardial or porcine
Homo-valves : human
Ross procedure
• Mechanical valves :
Cage-ball : Starr-Edwards
Mono-leaflet : Björk-Shiley
Bi-leaflet : St-Jude
Bioprosthetic valves
• Pericardial valves
• Porcine valves
Mechanical valves
• Caged-ball :
1960 (Starr-Edwards)
• Mono-leaflet :
• Bi-leaflet :
Surgery
Surgery
Stenosed valve
Mechanical valve
Animation: http://www.healthcentral.com/heart-disease/valves/
http://heart-surgeon.com
Cardiovascular
Structure
& Function