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