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2. Southwestern Illinois EMS System
Introduction to
Cardiac
Anatomy and Physiology

3. Introduction Cardiovascular disorder Heart disease
Diseases, conditions that involve heart, blood vessels
Heart disease
Conditions affecting heart

4. Introduction Coronary heart disease Coronary artery disease
Coronary arteries, resulting complications
Angina pectoris, acute MI
Coronary artery disease
Affects arteries that supply heart muscle with blood

5. Risk Factors & Prevention Strategies
Nonmodifiable (fixed) risk factors
Modifiable risk factors
High blood pressure
Elevated serum cholesterol levels
Tobacco use
Diabetes
Traits, lifestyle habits that may increase chance of developing disease
Nonmodifiable (fixed) risk factors
Heredity
Race
Gender
Advancing age
Modifiable risk factors
High blood pressure
Major risk factor for heart disease, stroke, end-stage renal disease
Risk of cardiovascular disease doubles for every 10-point increase in diastolic BP, every 20-point increase in systolic BP
Elevated serum cholesterol levels
LDL move cholesterol from liver through blood, bad cholesterol
If not removed from blood, builds up in arteries, narrows arterial walls, athersclerosis
HDL
Move cholesterol from body tissues, organs through blood, back to liver, broken down, recycled
Exercise, physical activity increases HDL concentration
Tobacco use
Heart attack increased 6 x in women, 3 x in men, 20 cigarettes/day
Diabetes
Type 2 diabetics, 2-4 x increased risk of coronary heart disease, 4 x increase in death from coronary heart disease

6. Risk Factors & Prevention Strategies
Modifiable risk factors
Physical inactivity
Obesity, body fat distribution
Metabolic syndrome
Physical inactivity
150+ minutes moderate physical activity/60 minutes vigorous physical activity/week reduces risk of coronary heart disease by 30%
Obesity and body fat distribution
Waist circumference 40+ inches in men, 35+ inches in women, increased cardiovascular risk
Metabolic syndrome
Group of disorders including high blood pressure, elevated insulin levels, excess body weight, 1+ abnormal cholesterol levels

7. Risk Factors & Prevention Strategies
Contributing risk factors
Stress
Inflammatory markers
Psychosocial factors
Alcohol intake
Stress
Persistent levels of epinephrine, increased blood pressure
Inflammatory markers
C-reactive protein released into bloodstream when active inflammation present
Atherosclerosisis, inflammatory disease
Fibrinogen necessary for normal blood clotting
High blood levels increase blood thickness, platelets clumping
Psychosocial factors
Depression, risk of heart disease
Lower socioeconomic groups
 Alcohol intake
3+ drinks/day, increased death risk
Light/moderate, protective effect
Increases HDL levels, protect against coronary heart disease through anti-inflammatory mechanism, reduce fibrinogen, hinder platelet clumping

8. Cardiovascular Anatomy & Physiology

9. Anatomy Review Blood vessels Arteries Arterioles Capillaries Venules
Veins
Arteries
Carry blood from heart to arterioles
Under high pressure
Arterioles
Smallest branches of arteries
 Connect arteries, capillaries
Capillaries
Smallest, most numerous
Connect arterioles, venules
Function as exchange vessels
Venules
Smallest branches of veins
Connect capillaries, veins
Veins
Carry deoxygenated blood to heart
Walls of veins thinner than arteries
Valves in larger veins of extremities, neck allow blood flow in one direction to heart

10. Anatomy Review Heart anatomy Location Mediastinum
Behind sternum, above diaphragm
Base
Apex
Mediastinum
Space between lungs in middle of chest
Sits behind sternum, just above diaphragm
2/3 lies to left of midline of sternum
1/3 lies to right of sternum
Base
Upper portion
Approximately level of 2nd rib
Apex
Lower portion
Formed by tip of left ventricle
Just above diaphragm between 5th & 6th ribs in midclavicular line
Tilted slightly toward left in chest
Anterior surface composed mostly of right ventricle
Inferior surface formed by right, left ventricles

11. Anatomy Review Heart Location
Heart lies in middle of thoracic cavity behind sternum, between lungs

12. Anatomy Review Heart anatomy Heart chambers Upper chambers
Right, left atria
Lower chambers
Right, left ventricles
Right, left atria
 Right atrium receives blood low in oxygen
From superior & inferior vena cava, coronary sinus
Coronary sinus, largest vein, drains heart
Left atrium receives oxygenated blood from lungs
From right, left pulmonary veins
When atria contract, blood pumped through valve into ventricles
Right, left ventricles
Walls thicker than atria
Right ventricle pumps blood to lungs
Left ventricle pumps blood to body
Apical impulse/point of maximal impulse, felt at apex

13. Anatomy Review Heart anatomy Septum Pulmonary circulation
Systemic circulation
Blood carried from heart to body through arteries, arterioles, capillaries
Blood returned to heart through venules, veins
Septum
Interatrial septum separates right, left atria
Interventricular septum separates right, left ventricles
 Separates heart into functional pumps
Right atrium, ventricle
Left atrium, ventricle
Pulmonary circulation
Right side of heart. low-pressure system, pumps unoxygenated blood through lungs to left side
Systemic circulation
 Left side, high-pressure pump, receives oxygenated blood, pumps to rest of body

14. Anatomy Review Heart anatomy Heart layers Endocardium Myocardium
Epicardium
Pericardium
Endocardium
Innermost, thin smooth layer of epithelium, connective tissue
Lines heart’s inner chambers, valves, chordae tendineae, papillary muscles
Continuous with innermost layer of arteries, veins, capillaries, creates continuous, closed circulatory system
 Myocardium
Middle, thick, muscular layer
Cardiac muscle fibers, pumping action
Epicardium is the outermost layer
Contains blood capillaries, lymph capillaries, nerve fibers, fat
Main coronary arteries lie on epicardial surface
Feed this area first
Enters myocardium, supplies inner layers with oxygenated blood
Continuous with inner lining of pericardium at apex
 Pericardium
Protects from trauma, infection
Fibrous parietal pericardium
Outer layer
Anchors heart to sternum, diaphragm
Helps prevent excessive movement in chest
Serous pericardium
Inner layer
Parietal layer lines inside of fibrous pericardium
Visceral layer adheres to outside of heart, forms the outer layer of heart muscle

15. Anatomy Review Heart anatomy Heart valves AV valves
Separate atria from ventricles
Tricuspid valve, between right atrium, right ventricle
Mitral/bicuspid valve lies between left atrium, left ventricle
Open when forward pressure forces blood forward
Close when backward pressure pushes blood backward
Tricuspid valve, between right atrium, right ventricle
3 separate cusps/flaps
Mitral/bicuspid valve lies between left atrium, left ventricle
2 cusps

16. Anatomy Review Heart anatomy Atrial kick
Blood flows continuously into atria
70% flows directly through, into ventricles before atria contract
When atria contract, additional 30% added to filling of ventricles
When ventricles contract (systole), pressure rises
Tricuspid, mitral valves close when pressure within ventricles exceeds that of atria

17. Anatomy Review Heart anatomy Semilunar (SL) valves
Pulmonic, aortic valves
Prevent backflow of blood from aorta, pulmonary arteries into ventricles
Close as ventricular contraction ends, pressure in pulmonary artery, aorta exceeds that of ventricles
Chordae tendinae, connective tissue, attached to AV valves underside & papillary muscles
Prevent backflow of blood from aorta, pulmonary arteries into ventricles
When right ventricle contracts blood flows through pulmonic valve into right, left pulmonary arteries
When left ventricle contracts blood flows through aortic valve into aorta
Chordae tendinae, connective tissue, attached to AV valves underside & papillary muscles
Papillary muscles relax, contract with ventricles
Adjust tension on chordae tendinae, preventing bulging too far into atria

18. Anatomy Review Blood flow through heart
Enters right atrium via superior, inferior venae cavae, coronary sinus
Right atrium through tricuspid valve into right ventricle
Right ventricle expels blood through pulmonic valve into pulmonary trunk
Flows through pulmonary arteries to lungs
Enters right atrium via superior, inferior venae cavae, coronary sinus
Low in oxygen, high in carbon dioxide
Right atrium through tricuspid valve into right ventricle
When ventricle contracts, tricuspid valve closes
Right ventricle expels blood through pulmonic valve into pulmonary trunk
Divides into right, left pulmonary artery, each carries blood to one lung

19. Anatomy Review Blood flow through heart
Low in O2, passes through pulmonary capillaries
From left atrium through mitral valve into left ventricle
Distributed throughout body through aorta, its branches
Low in O2, passes through pulmonary capillaries
Direct contact with alveolar-capillary membrane, oxygen & carbon dioxide exchanged, then to pulmonary veins
Carbon dioxide exhaled as left atrium receives oxygenated blood from lungs
From left atrium through mitral valve into left ventricle
Left ventricle contracts, mitral valve closes
Leaves through aortic valve into aorta

20. Anatomy Review Blood flow through heart
Tissues of head, neck, upper extremities via superior vena cava
Lower body via inferior vena cava
Superior, inferior vena cava carry contents into right atrium
Superior, inferior vena cava carry contents into right atrium
Blood flows from the right atrium through the tricuspid valve into the right ventricle

21. Anatomy Review Cardiac cycle
Repetitive pumping process, events associated with blood flow through heart
Systole
Diastole
Systole
Chamber contracts blood, being ejected
Atria, ventricles have systolic phase
Diastole
Relaxation period, chambers allowed to fill
Atria, ventricles have diastolic phase
Myocardium receives fresh oxygenated blood from coronary arteries during ventricular diastole

22. Anatomy Review Cardiac cycle
Depends on cardiac muscle ability to contract, condition of heart’s conduction system
Pressure with each chamber rises in systole, falls in diastole
Conduction system provides timing of events between atrial, ventricular systole

23. Anatomy Review Coronary arteries Right, left Main arteries
Left anterior descending (LAD), left circumflex (LCX), right coronary artery (RCA)
Lie on outer surface of heart
Right, left
1st branches off proximal aorta
Openings just beyond cusps of aortic SL valve
When contract, flow to heart tissues reduced, vesicles compressed
Fill when ventricles relaxed
Lie on outer surface of heart
Penetrate heart’s muscle, supply endocardium, myocardium with blood

24. Anatomy Review Coronary Arteries
3 major coronary arteries are left anterior descending (LAD; also called anterior intraventricular artery), left circumflex (LCX), right coronary artery (RCA)

25. Anatomy Review Coronary veins Travel alongside arteries
Coronary sinus, largest vein, drains heart
Lies in groove that separates atria from ventricles
Drains into right atrium

26. Anatomy Review Heart rate Affected by sympathetic, parasympathetic ANS
Chronotropic effect
Inotropic effect
Dromotropic effect
Affected by sympathetic, parasympathetic of ANS
Sympathetic division prepares body to function under stress, “fight-or-flight”
Parasympathetic division conserves, restores body resources, “feed-and-breed”
Chronotropic effect
Change in heart rate
Positive effect, increase
Negative effect, decrease
Inotropic effect
Change in myocardial contractility
Dromotropic effect
Speed of conduction through AV junction
Positive effect, increase in velocity
Negative effect, decrease in velocity

27. Anatomy Review Heart rate Baroreceptors
Specialized nerve tissue (sensors)
Found in internal carotid arteries, aortic arch
Detect changes in blood pressure
When stimulated cause sympathetic/parasympathetic response
 Will “reset” to new “normal” after few days of exposure to specific pressure
Sympathetic, adrenergic response
Parasympathetic, cholinergic response

28. Anatomy Review Heart rate Chemoreceptors
In internal carotid arteries, aortic arch, medulla detect changes in concentration of hydrogen ions (pH), O2, carbon dioxide in blood

29. Anatomy Review Heart rate Parasympathetic stimulation
Parasympathetic fibers supply sinoatrial node, atrial muscle, & AV junction of heart by vagus nerves
Slows sinoatrial node discharge rate
Slows conduction through AV node
Decreases atrial contraction rate
Can cause small decrease in ventricular contraction force
Acetylcholine (neurotransmitter) released when parasympathetic nerves stimulated
Binds to parasympathetic receptors

30. Anatomy Review Heart rate Sympathetic stimulation
Sympathetic nerves supply specific areas of heart’s electrical system, atrial muscle, ventricular myocardium
When stimulated, norepinephrine released
Increases in heart rate shorten all phases of cardiac cycle
When stimulated, norepinephrine released
Increases contraction force
Increases heart rate
Increases blood pressure

31. Anatomy Review Heart rate
Increases in heart rate shorten all phases of cardiac cycle
Electrolyte, hormone levels, medications, stress, anxiety, fear, body temperature can influence heart rate
Heart rate increases when body temperature increases, decreases when body temperature decreases
If ventricles do not have time to fill
Amount of blood sent to coronary arteries reduced
Amount of blood pumped out of ventricles decreases
Signs of myocardial ischemia may be seen

32. Heart as Pump Venous return
Most important factor determining amount of blood pumped out by heart is amount of blood flowing into right heart

33. Heart as Pump Cardiac output
Amount of blood pumped into the aorta each minute by heart
Defined as stroke volume x heart rate
Stroke volume determined by
Preload
Afterload
Preload
Force exerted on walls of ventricles at end of diastole
More blood returning to right atrium increases preload
Less blood decreases preload
Afterload
Pressure/resistance against which ventricles must pump to eject blood
Influences
Arterial BP
Ability of arteries to become stretched
Arterial resistance
Lower resistance, more easily blood ejects
Increased afterload increases heart’s workload
Increased blood thickness
High BP

34. Heart as Pump Cardiac output Frank–Starling’s law
Greater the volume of blood in heart during diastole (preload), the more forceful cardiac contraction & more blood ventricle will pump (stroke volume)
Important that heart adjust its pumping capacity in response to changes in venous return
During exercise, heart muscle fibers stretch in response to increased volume (preload) before contracting
Stretching of muscle fibers allows heart to eject additional volume with increased force
increasing stroke volume & cardiac output

35. Heart as Pump Cardiac output Frank–Starling’s law
Factors that increase cardiac output include increased body metabolism, exercise, age & size of body
Factors that may decrease cardiac output include shock, hypovolemia, heart failure
Heart failure may result from any condition that impairs preload, afterload, cardiac contractility, or heart rate
As heart begins to fail, body’s compensatory mechanisms attempt to improve cardiac output by manipulating 1+ of these factors

36. Conclusion
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