Cardiovascular Structure & Function
Jan 20, 2016
Cardiovascular Structure
& Function
Cardiovascular Structure
& Function
• 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
IntroductionIntroduction
• 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
Circulatory systemCirculatory system
1. Left ventricle2. Aorta3. Arterial system4. Vena cava5. Right atrium6. Right ventricle7. Pulmonary artery8. Lungs9. Pulmonary veins10. Left atrium1. Left ventricle
Heart valves Heart valves
M
AT
P
Pulmonary
Aortic
Mitral Tricuspid
Systolic and Diastolic phases Systolic and Diastolic phases
Diastolic phase =Ventricular filling
Systolic phase =Ventricular ejection
Cardiac cycle Cardiac cycle
Systole
DiastoleAnimation: http://library.med.utah.edu/kw/pharm/hyper_heart1.html
Aortic and Ventricular PressuresAortic and Ventricular Pressures
0
50
100
80
120
160
Pre
ssur
e (m
mH
g)L
V v
olum
e (m
L)
Ejection
PA
PLV
Left Atrium 2-11Left ventricle 90-140 / 5-12Aorta 90-140 / 60-90
Right Atrium 0-8Right ventricle 15-30 / 0-8Pulmonary artery 15-30 / 4-12
Normal pressuresNormal pressures
Unit = mmHg [1 mmHg = 133 Pa]
Intra-cardiac and arterial pressures Intra-cardiac and arterial pressures
HypertensionHypertension
Hypertension is defined as an abnormal increase in arterial pressure
Hypertension results in an increase in ventricular work and ventricular hypertrophy
Pressure and FlowPressure and Flow
0 0.5 1 1.50
50
100m
mH
g
0 0.5 1 1.50
200
400
time in s
mL
/s
Systolic Pressure
Diastolic Pressure
Systolic pressure = maximal pressureDiastolic pressure = minimal pressure
CATEGORY SYSTOLIC (mmHg) DIASTOLIC (mmHg)
Normal < 130 < 85
Normal ++ 130-139 85-89
Hypertension
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
A very low pressure should also by examined by a Doctor.
Classification of arterial pressure (> 18 years)Classification of arterial pressure (> 18 years)
Ventricular pressure-volume curves Ventricular pressure-volume curves
60 80 100 120 140 1600
20
40
60
80
100
120
0 0.2 0.4 0.6 0.80
50
100
0 0.2 0.4 0.6 0.8
80
100
120
140
160
Time (s)
Pre
ssu
re (
mm
Hg
)V
entr
icu
lar
Vo
lum
e (m
L)
Ven
tric
ula
r p
ress
ure
(m
mH
g)
Ventricular volume (mL)
1
1
1
2
2
23
3
3
4
4
4
1. Isovolumetric contraction2. Ventricular ejection3. Isovolumetric relaxation 4. Ventricular filling
1
1
Stroke volume
Strokevolume
P : Ventricular pressureV : Ventricular volume
Ventricular work Ventricular work
60 80 100 120 140 1600
20
40
60
80
100
120
Ve
ntri
cula
r P
ress
ure
(m
mH
g)
Ventricular volume (mL)
1 J
Effect of systemic hypertensionEffect of systemic hypertension
80 120 1600
100
200
80 120 1600
100
200
0 0.5 1 1.50
100
200
0 0.5 1 1.50
100
200
Normal pressures
Severe hypertension
1 J
1.5 J
Ventricular work as a f(preload,afterload)Ventricular work as a f(preload,afterload)
Factors influencing flow and pressureFactors influencing flow and pressure
Mean pressure (MAP) and pulsed pressure (PP)Mean pressure (MAP) and pulsed pressure (PP)
MAP 2/3 DP + 1/3 SP
PP = SP DP
SP (systolic pressure)
DP (diastolic pressure)
MAP (mean pressure)PP
Normal conditions (120/80 mmHg) : R = 1.1 mmHg.s/mLC = 2.0 mL/mmHg
Severe hypertension (190/115 mmHg) : R = 1.7 mmHg.s/mLC = 0.8 mL/mmHg
Resistance and compliance Resistance and compliance
Resistance : R MAP / CO MAP : mean arterial pressureCO : cardiac output
Compliance : C SV / PP SV : stroke volume PP : pulse pressure
Normal flow rate : SV = 70 mL, CO = 5L/min
Resistance : R MAP / COR increases MAP increases
Compliance : C SV / PPC decreases PP increases
0 0.5 1 1.50
50
100
mm
Hg
MAP
PP
Resistance and compliance Resistance and compliance
Hypertension and aortic pressure Hypertension and aortic pressure
0 0.5 1 1.50
100
200
0 0.5 1 1.50
100
200
Normal (120 / 80)
Severe hypertension (190 / 115)
MAP
PP
R = 1.1 mmHg.s / mLC = 2.0 mL / mmHg
MAP = 95 mmHgPP = 40 mmHg
R = 1.7 mmHg.s / mLC = 0.8 mL / mmHg
MAP = 140 mmHgPP = 75 mmHg
MAP
PP
140
95
Arterial Pressure 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 reflectionArterial pressure and wave reflection
aortaFemoral a
arterydorsalis
pedis
.......................
.......................
......................
......................
...................
..............
Incident wave
Reflected wave
Arterial pressure and wave reflectionArterial pressure and wave reflection
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
Heart Sounds Heart Sounds
1st stethoscope1st 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 stethoscopesExamples of stethoscopes
In 1819, the French doctor René Laënnec invented the stethoscope.
En 1851, Dr. Marsh developed the 1st commercial model.
Examples of stethoscopesExamples of stethoscopes
Pathological heart sounds 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 Aortic stenosis
Animation: http://www.healthcentral.com/heart-disease/valves/
Aortic valveNormal vs Stenosed
Aortic valveNormal vs Stenosed
Aortic stenosis : different originsAortic stenosis : different origins
Congenital
Rhumatismal
Calcification
Aortic stenosisAortic stenosis
Valvular surgeries in Canada (1996-1997)
The most common valvulopathy in industrial countries. Prevalence 1 to 2 % in people > 65 years old.
Carabello et al. NEJM, 1997
Aortic stenosisAortic stenosis
SymptomsSymptoms
• Angina pectoris
• Syncope
• Intolerance to exercise
Investigation of the severity of aortic stenoses
Investigation of the severity of aortic stenoses
- Gorlin Equation
- Energy loss coefficient
Valve replacementValve replacement
Xeno-valves : pericardial or porcine
Homo-valves : human
Ross procedure
•Biological valves :
Cage-ball : Starr-Edwards
Bi-leaflet : St-Jude
Mono-leaflet : Björk-Shiley
• Mechanical valves :
Bioprosthetic valvesBioprosthetic valves
• Pericardial valves
• Porcine valves
Mechanical valvesMechanical valves
• Caged-ball : 1960 (Starr-Edwards)
• Bi-leaflet :
• Mono-leaflet :
SurgerySurgery
SurgerySurgery
Stenosed valve Mechanical valve
http://heart-surgeon.comAnimation: http://www.healthcentral.com/heart-disease/valves/
Cardiovascular Structure
& Function
Cardiovascular Structure
& Function