1. Cardiovascular Physiology A
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2. Objectives To learn the basic anatomy and physiology of the heart
Muscle/ pump
To understand the mechanism for the delivery of oxygen and nutrients to the organs and tissues of the body
To become familiar with mechanisms to control blood pressure
To understand the process of atheroma formation (Next Class)
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3. Outline Needs for energy distribution Anatomy of the heart
The heart as a pump
Circulation
Introduction to EKGs
Blood pressure
Atheroma formation (next lecture)
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4. The Need for Circulation
All living cells require metabolic substrates (e.g. oxygen, glucose, amino acids) and a mechanism to remove the byproducts of metabolism (e.g. carbon dioxide, lactic acid- stuff we need to remove)
In human beings most cells are not in contact with the external environment
The ultimate purpose of the cardiovascular system is to facilitate exchange of gases, fluid, electrolytes, large molecules and heat between cells and the outside environment
The heart and vasculature ensure that adequate blood flow is delivered to organs so that this exchange can take place.
Klabunde, RE Cardiovascular Physiology Concepts Lippincott, Williams and Wilkins, 2005
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5. Exchanges External: Internal: Lungs (oxygen, carbon dioxide)
Gastrointestinal tract- guts (glucose, amino acids, fatty acids, etc. and elimination.)
Kidneys (water, electrolytes, and elimination)
Skin (water, electrolytes, heat)
Internal:
Arteries – Arterioles - Capillaries (close to cells for nutrient exchange) – Venules - Veins
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6. Capillary – no muscle – where exchanges take place
Test material***
Capillary – no muscle – where exchanges take place
- System is very important
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7. Circulation
Veins
Heart
Aorta
Delivered in parallel to organs
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9. Heart Anatomy Heart Muscles Right Atrium Right Ventricle Left Atrium
Left Ventricle
Heart Valves:
Between the atria and ventricles
Right: Tricuspid Left: Mitral
Between ventricles and outflow
Right: Pulmonic Left: Aortic
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12. Cardiac Cycle
Rhythmic contraction of the heart relies on the organized propagation of electrical impulses along its conduction pathway.
The electrical impulse spreads along each cardiac cell and rapidly between neighbouring cells
Electrical action potential leads to physical contraction of the cardiac muscle cells
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16. Heart Sounds First Heart Sound: Second Heart sound:
Closing of mitral and tricuspid valves and contraction of the Ventricles
Second Heart sound:
Closure of the Aortic and Pulmonary valves
Systole: (Contraction)
The time between the 2 heart sounds
Diastole: (Relaxation)
The time between the second heart sound and the first
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17. Electrocardiogram
Measures the electrical currents generated by the depolarization and repolarization of the cardiac cells
Diagnosis:
Rhythms
Blockages
An indication of heart diseases
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18. Not in exam***
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19. Refer to Page 24 in your handout (Chapter 13)19
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20. Summary 1 Heart is a very efficient pump
Pump needs a distribution system
Arteries
Veins… because system is closed
Why distribution?
Needs a means of carrying blood
Cells need O2 & nutrients for metabolisms to work
Closed system… Returns deoxygenated blood & metabolites
Needs an electrical system
To initiate/transmit impulses, create action potentials (AP) to accomplish specific cell function (i.e., pumping action)
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21. Summary 2 If you understand the basic elements … then you can appreciate what might go wrong
Problem with Pump – when aging pump doesn’t work well – high salt intake
Congenital – perforation of the septal wall and/or malformation of heart vessels
Disease – enlargement, thickening
Failure of the valves – disease such as syphilis –Leakage – pressure build up behind fluid in lungs/extremities
atrial enlargement
Blockages
Clogged arteries – insufficient fuel – cell death
Heart cannot contract
Ruptures
Aneurysm – weakening aorta
Changes over time
In flexibility/elasticity of distribution system
Electrical Interruptions
Conduction blocks – may need pacemaker
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22. Summary 3 … then primary care assessment
History – The story
Pain on exertion or at rest
Shortness of breath, etc.
Look – diagnosis
Edema – swelling – blood flow doesn’t get pumped back
Listen
The heart sounds
Blood pressure – resistance in the distribution system
Feel
The pulses
ECG
Assess the electrical conductivity & efficiency of heart cycle
THESE ARE THE BASIC TOOLS FOR THE GPs
Obviously more sophisticated methods are needed/available for further investigation
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23. Blood Pressure
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24. Objectives Review of structure & function
Learn the role of various blood vessels in oxygen and nutrient supply and removal
Blood Pressure and its determinants
Understand how different factors might influence blood pressure levels
Become familiar with mechanisms of controlling blood pressure
Learn how blood pressure is measured
Hypertension or High blood pressure
Impact of hypertension
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25. Outline Structure of blood vessels Blood circulation
Capillary exchange
Physiologic methods to control blood pressure
Blood pressure measurement
Causes of altered blood pressure
Guidelines for measuring BP
Public health consequences of high BP
Management of High Blood Pressure – Lifestyle
Management of High Blood Pressure – Drug therapy
Benefits of treating/controlling High Blood Pressure
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26. Normal Arterial Wall

27. Blood Vessel Structure
Intima: Inner Layer – Endothelium and sub endothelial layer-loose connective tissue-
Media: Smooth Muscle
Adventitia: Fibrous Tissue/Connective tissue
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28. Blood Vessel Structure **
Capillary and venules have smooth muscles - FALSE

29. Blood Flow During Rest

30. Capillary Exchange Most capillary exchange is by
diffusion (between cells)
or transcytosis
(through cells)
Gases (O2) (CO2) diffuse freely
Capillary filtration and Absorption is by bulk flow:
Hydrostatic pressure (pushes)
Osmotic pressure (mainly proteins- pulls fluid)

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32. Venous Blood Flow Blood vessels are similar
(in reverse) to the arterial
system
Small very thin-walled venules
to larger veins
Blood begins at very
low pressure
Moved by skeletal muscles,
respiratory pump
Valves prevent backflow
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33. *Handling the Overflow
Outflow is greater than inflow
Return is helped by the Lymphatic System
Lie next to the capillaries
Even thinner walls than capillaries
Fluid enters (one-way)
Empty into venous system or continue into larger lymph ducts
Fluid is moved by
smooth muscle contractions, endothelial contractions, skeletal muscle contractions
Valves prevent backflow
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34. Lymphatic System Returns fluid and proteins to circulatory system
Picks up fat absorbed by small intestine
Filter to capture and destroy pathogens
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35. Edema: Swelling “Accumulation of fluid in the interstitial space”
Edema varies with capillary exchange:
A. Inadequate lymphatic drainage
Obstruction (parasite, cancer, fibrous growth)
B. Filtration is much greater than absorption
Venous back-up (heart failure)
Low plasma protein concentration (starvation)
Increased interstitial plasma protein
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36. Blood Pressure Systolic pressure: Ventricles contracting
Diastolic pressure: Ventricles relaxing
(but there is still pressure in the arteries)
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37. Determinants of Blood Pressure
Cardiac Output (CO)
Peripheral Resistance (TPR)
MAP = CO X TPR
CO = Stroke Volume X Heart Rate
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38. BP Regulation – Role of CV & Renal Systems
MAP = CO X TPR
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39. Factors influencing MAP
1/R = 1/R1 + 1/R2+…
Volume
CO=SVXHR
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40. Factors Affecting Blood Pressure
Blood volume
Raise intake of fluids
Blood loss
These are “regulated” by vasoconstriction of the vessels, sympathetic nervous system (make the blood pump faster) and the renal system
Arterial-venous blood distribution
Heart pump effectiveness
Resistance in the blood vessels
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41. Blood Pressure Controls
Local:
Myogenic autoregulation of blood flow
Meets the needs of the respective tissue/organ
Paracrine concentrations stimulate
smooth muscle contractions
Adjusts metabolic product concentrations
Central:
Sympathetic nervous system (fight or flight) stimulates hormone release causing vasoconstriction and kidney excretion
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42. Homeostatic Regulation: Baroreceptors
Carotid arteries (on the way to the brain)
Aortic arch (on the way to the heart)
Sensitive to distension of the vessel
Send message to medulla
Adjust sympathetic and parasympathetic activity
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43. BP Regulation – Orthostatic Hypotension heart isn’t adjusting but the pressure is high so you get dizzy
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44. Blood Pressure Regulation
Systems involved:
Heart
Blood vessels
Kidneys
Hormones (modulate the functions of the above)
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45. Blood Pressure Measuring Devices
Sphygmomanometer
Aneroid manometers
Random Zero Sphygmomanometers
Digital devices
Ambulatory BP Monitors
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46. Blood pressure Measurement
Use Sphygmomanometer
1. Stop the blood flow
2. Release pressure gradually
The first sound we hear will be the highest pressure = systolic
3. When there is no sound the ventricles are relaxed.
There is still pressure in the arteries = diastolic
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47. Blood Pressure Cuff
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48. Effect of Hypertension
On the heart itself: Heart attack, Myocardial infarction
On the brains: Stroke
On the kidneys: kidney failure/chronic kidney disease
Eyes: retinopathy: retinal microvascular signs
Periphery: Peripheral vascular disease

49. Errors in the Measurement of BP
Patient Errors
Observer Errors
Equipment Errors
1994
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50. Hypertension or High BP
Hypertension refers to a blood pressure measurement of greater than 140/90 mm Hg (or on medication)
consistently, at rest
Pre Hypertension Blood pressure is between 120/80 mmHg and 139/89 mmHg.
You will see in manuals 90%: Unknown cause = Essential Hypertension. This is incorrect. Most can be attributed to some factor, usually overweight, high sodium intake, alcohol, physical inactivity, etc.
Pathogenic process:
Vessels: Damages endothelial wall, promoting the formation of atherosclerotic plaques
Heart: Increases strain on the heart, leading to hypertrophy (pump is working harder), then back-up causing pulmonary edema, and then congestive heart failure 50
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51. Hypertension target in terms of definition
Levels for defining hypertension have shifted down, from 165/95 mmHg to DBP >=90 mmHg to currently 140/90 mm Hg or on treatment
Canadian recommendations include for diagnosis at different visits specific BP levels + presence of target organ damage or BP >=140/90 at visit 5
Epidemiologic diagnosis usually based on one or the mean of a few measures (2-6) >=140/90
Creates some difficulty for comparison of studies
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52. Prevalence of High Blood Pressure in Canada CHHS- 1986-1992
BP > 140/90 mm Hg or treated;
survey n = 23,129
4.1 million hypertensive adults
Total: 22%; Women 18%
Men 26%
Canadian Heart Health Surveys
Joffres et al. AJH, 1997
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53. HBP Was a Challenge In Canada
21%
13%
43%
22%
Hypertensive patients
who are treated
but BP uncontrolled
and BP controlled
who are unaware
Patients who are aware
but remain untreated
and BP uncontrolled 9%
Diabetic patients
who are treated and
BP controlled
Prevalence: 22% yrs or about 4 million Canadians
Joffres et al., Am J Hypertens 2001; 14:
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54. Percentage with hypertension† who are aware, treated by medication, controlled,‡ CHMS 2007-2009
‡ measured SBP lower than 140 mm Hg and DBP lower than 90 mm Hg
E interpret with caution (coeffi cient of variation 16.6% to 33.3%)
Note: Because of rounding, the sum of the estimates exceeds 100%.
Source: Canadian Health Measures Survey.
Conclusion: Better treatment and control now, but numbers are still high 4.6 million adults yrs and prevalence is not just slightly lower at 19% vs 22% in the 80s and 90s.
Prevalence: 19% (4.6 million) of Canadian adults aged 20 to 79 years
Wilkins K, Campbell NR, Joffres MR, McAlister FA, Nichol M, Quach S,
HL, Tremblay MS. Blood pressure in Canadian adults. Health Rep. 2010
Mar;21(1):37-46
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55. Global Prevalence of HBP
Nearly 1 in 5 persons live with HBP
i.e. Almost 1.5 billion people have hypertension in the world
HBP = Silent killer - Symptoms are not overt & hence more people are UNAWARE
In Canada about 19% of the adult population is hypertensive (approx. 4.6 million) (2009)
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56. Attributable Mortality by Selected Factors
Ezzati et al. Lancet 2002
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57. % Attributable DALY by Selected Factors
DALY: Disability Adjusted Life Years
Ezzati et al. Lancet 2002
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58. Risk Factors for High Blood Pressure
Family history
Overweight
Physical inactivity
Alcohol
Diet (high sodium and low potassium, magnesium, calcium.
(smoking- lose appetite – blood pressure goes down)
Age- But no or little increase with age in Brazil, Papua New Guinea, South Korea, Tokelau Islands etc. Raises question of the influence of lifestyle on age related increase in BP.
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59. Building Awareness of HBP
National and International Hypertension Societies. See
World Hypertension League
World Hypertension Day
2005 – Awareness of hypertension
2006 – Treat to Goal
2007 – Healthy Diet…Healthy Blood Pressure
2008 – Measure your blood pressure … at Home
2009 – Salt and Hypertension
2010 – Healthy Weights-Healthy Blood pressure
2011 – Know Your Numbers and Target Your Blood Pressure
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61. Hypertension Treatment
LIFESTYLE MANAGEMENT
Reduce salt intake, weight, chronic alcohol intake
High fruit/vegetable diet,
Stop smoking
Increase exercise
DRUGS:
Diuretics first drug of choice
Beta-blocking drugs to bind beta receptors
Calcium channel blockers – helps smooth muscle not to constrict so easily
ACE inhibitors and angiotensin receptor blockers (ARBs) - decrease angiotensin activity
Renin-Angiotensin-Aldosterone Systems (RAAS)
Combination therapy for high risk patients
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62. Guidelines – Management of HBP
Canadian High Blood Pressure Education Program (CHEP)
USA -Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC)
WHO/International Society of Hypertension (WHO-ISH)
European Society of Hypertension (ESH)
National Societies (Culturally sensitive)
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63. The “Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure” (JNC VII)
Provides a guideline for hypertension prevention and management. The following are the report’s key messages:
In persons older than 50 years, systolic blood pressure greater than 140 mmHg is a much more important cardiovascular disease (CVD) risk factor than diastolic blood pressure.
The risk of CVD beginning at 115/75 mmHg doubles with each increment of 20/10 mmHg; individuals who are normotensive at age 55 have a 90 percent lifetime risk for developing hypertension. 63
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64. JNC VII (Cont’d)
Individuals with a systolic blood pressure of 120–139 mmHg or a diastolic blood pressure of 80–89 mmHg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD. (High normal BP)
Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (angiotensin converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, calcium channel blockers). 64
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65. JNC VII (Cont’d)
Most patients with hypertension will require two or more antihypertensive medications to achieve goal blood pressure (<140/90 mmHg, or <130/80 mmHg for patients with diabetes or chronic kidney disease).
If blood pressure is >20/10 mmHg above goal blood pressure, consideration should be given to initiating therapy with two agents, one of which usually should be a thiazide-type diuretic.
The most effective therapy prescribed by the most careful clinician will control hypertension only if patients are motivated. Motivation improves when patients have positive experiences with, and trust in, the clinician.
Empathy builds trust and is a potent motivator. 65
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66. How to measure BP at home
Do not talk
Keep back supported
Place cuff mid-arm at heart level
Be seated
Ensure arm is supported
Keep legs uncrossed
Keep feet flat on the floor
CHEP 2008
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67. Leading diagnoses resulting in visits to physician offices in Canada25 20
Routine medical
exams
Depression
Acute respiratory
tract infection 15
Diabetes
Million visits/year
Hypertension 10
URTI: Upper Respiratory Tract Infections.
Patient visits to office-based physicians for essential hypertension numbered 18.9 million in 2002, a 10% increase from the previous year. Most visits were to GP/FMs (90%). 55% of visits were made by female patients and 45% were made by males. The age distribution was as follows: More than 81% of visits involved a drug recommendation. • Community retail pharmacies dispensed an estimated 52.7 million prescriptions for anti-hypertensive  agents in 2002, compared with 34 million in Source IMS Canada with permission. 5
Source: IMS HEALTH Canada
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68. Benefits of Lowering Blood Pressure
In clinical trials, antihypertensive therapy has been associated with reductions in
(1) stroke incidence, averaging 35–40 percent;
(2) myocardial infarction (MI), averaging 20–25 percent; and
(3) Heart Failure, averaging >50 percent.
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69. It is estimated that in patients with stage 1 hypertension (SBP 140–159 mmHg and/or DBP 90–99 mmHg) and additional cardiovascular risk factors, achieving a sustained 12 mmHg reduction in SBP over 10 years will prevent 1 death for every 11 patients treated.
In the added presence of CVD or target organ damage, only nine patients would require such BP reduction to prevent one death
Ref: adapted from SHEP, SYST-EUR, STONE studies.
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70. Effect of SBP and DBP on Age-Adjusted CAD Mortality: MRFIT
CAD Death Rate per 10,000 Person-years
100+
90-99
80-89
75-79
70-74
<70
<120
160+
Diastolic BP (mmHg)
Systolic BP (mmHg)
20.6
10.3
11.8
8.8
8.5
9.2
12.6
12.8
13.9
24.6
25.3
25.2
24.9
16.9
23.8
31.0
25.8
34.7
43.8
38.1
80.6
37.4
48.3
Neaton et al. Arch Intern Med 1992; 152:56-64.
CAD Death rate per 10,000 person years
Multiple Risk Factor Intervention Trial (MRFIT)
Systolic blood pressure (SBP) and diastolic blood pressure (DBP) have been shown to be strongly associated with coronary artery disease (CAD) mortality. The combined effect of SBP and DBP on age-adjusted CAD mortality is shown on this slide. These data, from a cohort of men screened for the Multiple Risk Factor Intervention Trial (MRFIT) and followed for an average of 12 years, show that SBP is actually a stronger predictor of death from CAD than DBP.
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Source:
Neaton JD and Wentworth D for the Multiple Risk Factor Intervention Trial (MRFIT) Research Group. Serum cholesterol, blood pressure, cigarette smoking, and death from coronary heart disease. Arch Intern Med 1992; 152:56-64.