Cardiovascular Structure & Function

Transcription

1 Cardiovascular Structure & Function

2 Cardiovascular system: The heart Arteries Veins Capillaries Lymphatic vessels

3 Weighting of the heart ceremony: Ancient Egyptians

4 William Harvey and Blood Flow April 1, 1578 June 3, 1657

5 Introduction The most basic functions of the cardiovascular system are: To deliver oxygen and nutrients to body tissues To remove waste To regulate temperature

6 Circulatory system

7 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

8 Heart valves Pulmonary Aortic T P M A Mitral Tricuspid

9 Systolic and Diastolic phases Diastolic phase = Ventricular filling Systolic phase = Ventricular ejection

10 Cardiac cycle Systole Animation: Diastole

11 Aortic and Ventricular Pressures LV volume (ml) Pressure (mmhg) Ejection P A P LV

12 Normal pressures Unit = mmhg [1 mmhg = 133 Pa] Left Atrium 2-11 Left ventricle / 5-12 Aorta / Right Atrium 0-8 Right ventricle / 0-8 Pulmonary artery / 4-12

13 Intra-cardiac and arterial pressures

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

15 Pressure and Flow mmhg Systolic Pressure Diastolic Pressure ml/s time in s

16 Classification of arterial pressure (> 18 years) Systolic pressure = maximal pressure Diastolic pressure = minimal pressure CATEGORY SYSTOLIC (mmhg) DIASTOLIC (mmhg) Normal < 130 < 85 Normal Hypertension STAGE 1 (Mild) STAGE 2 (Moderate) STAGE 3 (Severe) STAGE 4 (Very Severe) >209 >119 A very low pressure should also by examined by a Doctor.

17 Ventricular pressure-volume curves Pressure (mmhg) Ventricular Volume (ml) Stroke volume Time (s) 4 1 Ventricular pressure (mmhg) Stroke volume Ventricular volume (ml) 1. Isovolumetric contraction 2. Ventricular ejection 3. Isovolumetric relaxation 4. Ventricular filling 2 1

18 Ventricular work Ventricular Pressure (mmhg) J P : Ventricular pressure V : Ventricular volume Ventricular volume (ml)

19 Effect of systemic hypertension 200 Normal pressures J Severe hypertension J

20 Ventricular work as a f(preload,afterload)

21 Factors influencing flow and pressure

22 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

23 Resistance and compliance Resistance : R MAP / CO Compliance : C SV / PP MAP : mean arterial pressure CO : cardiac output SV : stroke volume PP : pulse pressure Normal conditions (120/80 mmhg) : Severe hypertension (190/115 mmhg) : R = 1.1 mmhg.s/ml C = 2.0 ml/mmhg R = 1.7 mmhg.s/ml C = 0.8 ml/mmhg

24 Resistance and compliance Normal flow rate : SV = 70 ml, CO = 5L/min Resistance : R MAP / CO R increases Compliance : C SV / PP C decreases MAP increases PP increases mmhg MAP PP

25 Hypertension and aortic pressure MAP Normal (120 / 80) PP R = 1.1 mmhg.s / ml C = 2.0 ml / mmhg MAP = 95 mmhg PP = 40 mmhg Severe hypertension (190 / 115) MAP PP 140 R = 1.7 mmhg.s / ml C = 0.8 ml / mmhg MAP = 140 mmhg PP = 75 mmhg

26 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.

27 Arterial pressure and wave reflection dorsalis pedis Femoral a artery aorta

28 Arterial pressure and wave reflection Incident wave Reflected wave

29 Heart Sounds

30 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

31 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

32 Examples of stethoscopes In 1819, the French doctor René Laënnec invented the stethoscope.

33 En 1851, Dr. Marsh developed the 1st commercial model. Examples of stethoscopes

34 Pathological heart sounds Several pathologies induce turbulence in the flow in the cardiovascular system. High frequencies in the turbulent flow generate audible sounds.

35 Aortic stenosis Animation:

36 Aortic valve Normal vs Stenosed

37 Aortic stenosis : different origins Congenital Rhumatismal Calcification

38 Aortic stenosis The most common valvulopathy in industrial countries. Prevalence 1 to 2 % in people > 65 years old. Valvular surgeries in Canada ( )

39 Aortic stenosis Carabello et al. NEJM, 1997

40 Symptoms Angina pectoris Syncope Intolerance to exercise

41 Investigation of the severity of aortic stenoses - Gorlin Equation - Energy loss coefficient

42 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

43 Bioprosthetic valves Pericardial valves Porcine valves

44 Mechanical valves Caged-ball : 1960 (Starr-Edwards) Mono-leaflet : Bi-leaflet :

45 Surgery

46 Surgery Stenosed valve Mechanical valve Animation:

47 Cardiovascular Structure & Function