Cardiovascular Structure Function Cardiovascular system The heart Arteries

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

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_heart 1. html

LV volume (m. L) Pressure (mm. Hg) Aortic and Ventricular Pressures PA 100 50 PLV 0 160 120 80 Ejection

Normal pressures Unit = mm. Hg [1 mm. Hg = 133 Pa] Left Atrium Left ventricle Aorta 2 -11 90 -140 / 5 -12 90 -140 / 60 -90 Right Atrium Right ventricle Pulmonary artery 0 -8 15 -30 / 4 -12

Intra-cardiac and arterial pressures

Hypertension is defined as an abnormal increase in arterial pressure Hypertension results in an increase in ventricular work and ventricular hypertrophy

Pressure and Flow mm. Hg Systolic Pressure 100 Diastolic Pressure 50 0 0 0. 5 1 1. 5 0 0. 5 1 time in s 1. 5 m. L/s 400 200 0

Classification of arterial pressure (> 18 years) Systolic pressure = maximal pressure Diastolic pressure = minimal pressure CATEGORY SYSTOLIC (mm. Hg) DIASTOLIC (mm. Hg) 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 (m. L) 0 0 160 1 140 1 4 0. 2 0. 4 0. 6 0. 8 2 1 Ventricular pressure (mm. Hg) Pressure (mm. Hg) Ventricular pressure-volume curves Stroke volume 120 100 3 2 80 60 Stroke volume 40 20 0 4 60 80 1 100 120 140 160 Ventricular volume (m. L) 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 (mm. Hg) Ventricular work 120 100 80 1 J 60 40 20 0 60 80 100 120 140 160 Ventricular volume (m. L) P : Ventricular pressure V : Ventricular volume

Effect of systemic hypertension 200 Normal pressures 100 1 J 0 0 0. 5 1 1. 5 0 80 120 160 200 Severe hypertension 100 0 0. 5 1 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 mm. Hg) : R = 1. 1 mm. Hg. s/m. L C = 2. 0 m. L/mm. Hg Severe hypertension (190/115 mm. Hg) : R = 1. 7 mm. Hg. s/m. L C = 0. 8 m. L/mm. Hg

Resistance and compliance Normal flow rate : SV = 70 m. L, CO = 5 L/min Resistance : R MAP / CO R increases MAP increases Compliance : C SV / PP C decreases PP increases MAP mm. Hg 100 PP 50 0 0 0. 5 1 1. 5

Hypertension and aortic pressure Normal (120 / 80) 200 MAP 100 95 PP 0 0 0. 5 1 MAP = 95 mm. Hg PP = 40 mm. Hg 1. 5 Severe hypertension (190 / 115) 200 MAP 140 100 0 R = 1. 1 mm. Hg. s / m. L C = 2. 0 m. L / mm. Hg PP 0 0. 5 1 R = 1. 7 mm. Hg. s / m. L C = 0. 8 m. L / mm. Hg MAP = 140 mm. Hg PP = 75 mm. Hg 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 . . . Incident wave Reflected wave . . . . . .

Heart Sounds

Heart Sounds Two heart sounds can be distinguished: S 1 and S 2. S 1 is synchronized with early systolic phase. S 2 is synchronized with the end of systolic phase. The frequencies are between 10 and 500 Hz with low intensity

1 st 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 1 st 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