CVPR 312 Cardiac Pathophysiology / Lecture 2 / Ischemic Heart Disease Flashcards Preview

CVPR 312 Cardiac Pathophysiology > CVPR 312 Cardiac Pathophysiology / Lecture 2 / Ischemic Heart Disease > Flashcards

Flashcards in CVPR 312 Cardiac Pathophysiology / Lecture 2 / Ischemic Heart Disease Deck (123):
1

Ischemic Heart Disease (IHD) is Characterized by changes in the cardiac muscle that occur when ?

Coronary arterial oxygen supply is inadequate to meet myocardial metabolic demands.

2

Coronary sinus SvO2 =

30%

3

Inadequate blood supply (circulation) to a local area due to blockage of the blood vessels to the area.

Ischemia

4

An oxygen deficiency in body tissues

Hypoxia

5

Hypoxemia

Decreased PaO2

6

Anoxia

Absence of oxygen

7

Cyanosis

a bluish skin tint caused by inadequate oxygenation of the bloodstream.

8

Myocardial Ischemia (MI) can be du to the following 2 things?

- Acute coronary thrombosis
- Coronary atherosclerosis

9

Most Common cause of death in the industrialized world

- 500,000 die annually
- 12 million affected in US

10

Risk Factors for Myocardial Ischemia

HTN
DM
Cigarette smoking
Hyperlipidemia …Cholesterol (LDL)
Obesity
Sedentary lifestyle
Psychological stress

11

Most frequent cause of coronary blood flow and myocardial ischemia ?

Atheromatous plaque

12

Coronary vasoconstriction / spasm Typically occurs at or near plaque and ?

damaged endothelium

13

Coronary emboli often results from ?

thrombi from LV or prosthetic valves

14

Severe hypotension

MAP < 45-55 mmHg = loss of coronary autoreg

15

In the precence of CAD pressure even higher than ___ may be needed to prevent ischemia.

70 mmHg

16

Causes of Myocardial Ischemia (cont.)

- Aortic Valve stenosis
- Hypertrophic cardiomyopathy
- Inflammatory dz of coronary arteries
- Congenital anomalies of the coronary circulation
- Extremely raid heart rate

17

Imbalance between O2 Sypply & O2 demand
Predisposes patients to ?

- Myocardial ischemia
- Ventricular dysfunction
- Electrical Instability
- MI
- Possible death from dysrhythmias or heart failure

18

At rest the myocardium extracts about ___________ of the O2 from coronary arterial blood

70-80%

19

Consequently, any increased O2 demand must be met by

increases in blood flow

20

In the myocardial oxygen supply - demand balance patients may develop myocardial ischemia if:

1.) Myocardial oxygen supply falls short of demand
2.) Myocardial oxygen demand exceeds supply

21

In regards to the coronary arterial blood supply, the
LEFT coronary artery supplies what?

Anterior & Lateral portions of the LV

22

In regards to the coronary arterial blood supply, the
RIGHT coronary artery supplies what?

RV & posterior LV
(80-90% of people)

23

% of Coronary venous blood that comes from the LV to the Coronary Sinus ?

75% of total

24

From the RV to the > ________ > RA

anterior cardiac vein

25

_____ _____ empty directly into all chambers (very small amount)

Thebesian veins

26

Normal coronary blood flow at rest?

225 ml/min

4 - 5 %

27

Normal coronary blood flow

- Phasic in nature esp. in LV
- Low flow during systole (compression)
- High flow during diastole (relazed state)

28

Normal coronary artery structure starting from the outside.

- Adventia
- Media
- Intima
- Endothelium
- Lumen

29

Angina Pectoris

Chest pain caused by fleeting deficiency in oxygen delivery to myocardium

30

Drug treatment of Angina Pectoris

- Nitroglycerin = vasodilator
- Beta blockers = block sympathetic beta adernergic
receptors.

31

The degree of coronary intraluminal obstruction correlates with anginal presentation. If strenuous exercise or strong emotion = chest pain (clasical angina), then we can conclude what ?

Intraluminal Obstruction of > 50%

32

The degree of coronary intraluminal obstruction correlates with anginal presentation. If the patient often has angina at rest, then we can conclude what?

Intraluminal Obstruction of > 80%

33

Prinzmatal's

Coronary vasospasm (no CAD) occurs typically at rest (morning hours)

34

Compensatory mechanisms for O2 supply/demand mismatch

- Coronary arteriolar vasodilation
- Coronary collateral circulation
- Anerobic metabolism

35

What is the primary controller of Coronary arteriolar vasodilation:

Local Metabolism

36

Blood flow is regulated by local arteriolar

Vasodilation

37

What is the major factor that controls coronary blood flow?

Oxygen Demand

38

What percentage of oxygen is removed as it goes through the heart?

70%

39

Coronary blood flow is directly proportional to ?

Metabolic consumption

40

If there is a small occlusion in coronary blood flow, what happens?

collateral flow may double to affected area over several days.

41

If there is a GRADUAL occlusion in coronary blood flow, what happens?

Collaterals develop progressively with the disease.

42

What happens when sclerotic process overwhelms the collateral capacity?

Heart Failure

43

Under resting conditions, cardiac muscle normally consumes ____ ____ to supply most of its energy instead of carbohydrates .

Fatty Acids

44

What % of energy is derived from fatty acids?

70%

45

Under what conditions must cardiac metabolism call on glycolysis mechanisms for energy ?

Under ANAEROBIC or ISCHEMIC conditions.

46

Glycolysis consumes large amounts of ____ _____ and at the same time forms large amounts of LACTIC ACID in the cardiac tissue ?

BLOOD GLUCOSE

47

What is one of the causes of cardiac pain under cardiac ischemic conditions?

LACTIC ACID build up in the cardiac tissue

48

Vagal stimulation by Acetylcholine causes what DIRECT effect?

Vasodilation

49

Indirect stimulation is a far more important role. Sympathetic Stimulation causes what?

↑HR
↑Contractility = ↑ metabolic demand > sets off local blood flow regulatory mechanisms for DILATING

50

Sympathetic Stimulats and their receptors ?

Epi
Noepi
a & b receptors

51

Vagal stimulation with its release of acetylcholine poduces:

↓HR
↓ contractility
> ↓ Cardiac Oxygen Consumption
= Indirectly constrict the coronary arteries

52

Typical Angina evoked by:

- Exertion
- Emotions
- Cold/heat exposure
- Meals
- Sexual Intercourse

Relieved by Rest

53

Stable Angina

- Reproducible and Predictable in onset

54

Atypical Angina

- No relationship to exertion

55

Unstable Angina

- New onset of typical angina
- Increasing in insensity or occurs at rest

56

Type of Angina that varies in symptoms ?

Prinsmtal's Angina

57

ECG Evaluation of an MI ?

- ST may be elevated or depressed
- T waves may be tall

58

ECHO Evaluation of an MI ?

Wall motion abnormalities

59

Thallium Scan Evaluation of an MI ?

Absence of thallium “cold spot” MI

60

Lab Evaluation of an MI ?

Troponin

Creatine Kinase (CK-MB) 30 – 220 U/L.

Lactate dehydrogenase (LDH) 100 - 220 U/L

Myoglobin (Mb) 30 – 90 µg/mL

61

Leading cause of death in industrialized countries?

CAD

62

Ischemic heart disease leads to what

-Angina
-MI
-Sudden Cardiac Death
-Chronic Heart Failure

63

Arteriosclerosis

Natural changes in the following:
- INTIMA
- CONNECTIVE TISSUE
- DIAMETER of ARTERY.

64

Atherosclerosis

pathologic phenomenon occurring in the following:
- coronary
- carotid
- iliac
- femoral arteries
- aorta.

65

Narrowing and hardening of the arteries leads to imbalance between what?

Supply and Demand which leads to ISCHEMIA.

66

Ischemic Heart Disease is a result of what

CAD (atherosclerosis)

67

How is Ischemia detected?

- Symptoms (angina)
- ECG (indirectly)

68

Cross Section of an artery on how atherosclerosis develops, starting from the inside?

- Endothelium
- Internal Elastic Tissue
- Smooth Muscle Cells
- External Elastic Tissue
- Connective Tissue

69

Inflammatory response is the result of

proliferation of tissue within the arterial wall which may result in obstruction of blood flow.

70

What are the causes of atherosclerosis?

↑ cholesterol
↑ triglycerides
↑ BP - turbulent blood flow
- tobacco smoke
- glycosylated substances

71

Response to injury hypothesis ?

Endothelium is injured > Platelets & monocytes adhere to endothelium > Release growth factors.

Monocytes become Macrophages & take up LDL & SMC's.

Smooth muscle proliferation & migrate from medial to intimal layer.

72

Migration to the intima smooth muscles with lipids form fatty streaks AKA ?

Foam Cells

73

Fibromuscular layer with cholesterol core ?

Fibromuscular plaque

74

Atherosclerosis affects what vessels?

Intermediate and Large arteries

75

Fatty lesions that develop on the inside surface of the artery.

Atheromatous plaque

76

Results of atheromatous plaques ?

↓ Lummen Size
↓ Blood Flow

77

How do atheromatous plaques begin?

they begin by deposition of cholesterol crystals in the intima and smooth muscle.

78

Minimal intrusion into vessel lumen ?

Fatty Streak

79

Artherosclerosis can result in ?

- Hypertensive Heart Disease
- Coronary Artery Occlusion
- ↑ cholesterol
- ↑ LDL

80

Good Cholesterol

HDL

81

Muscle cells die after

1 hour of ischemia

82

↑ in Cardiac Output results mostly from ?

Sympathetic Stimulation

83

Circulatory response to exercise challenge causes an increase in arterial pressure by ?

- Vasoconstriction of arterioles
- ↑ contractility of the heart
- ↑ filling pressures

84

A MASS Sympathetic discharge causes what ?

↑ Arterial pressure
↑ in rate & strength = ↑ Cardiac Output

Muscle walls of veins are contracted = ↑ venous return / preload.

85

SVR formula ?

80 X (MAP-RAP)
_____________
CO

86

Platelet aggregation and thrombus formation is secondary to what ?

Atherosclerosis

87

Coronary vasospasm can lead to what ?

Rupture of plaque

88

What can cause a vasospasm ?

Platelet activation

89

Area of the myocardium that is affected as a result of an MI?

Infarct

90

The percentage of heart attacks that are fatal?

33%

91

Neutorphils that cause tissue damage are activated by ?

Lack of O2

92

Damaged myocardial tissue is replaced by what ?

Connective Tissue

93

Often the origin of infarct moves from endocardium to epicardium. This is know as what?

Subendocardial myocardial infarction

94

Decreased cardiac output causes death because ?

- Systolic Stretch
- Cardiogenic Shock

95

Daming of venous blood causes death because?

- It increases capillary hydrostatic pressures
- Leads to Edema and Congestion

96

Fibrillation can cause death and is most often the result of what?

- Depletion of K+
- Injury Current
- Sympathetic reflexes
- Abnormal conduction pathways

97

Hemodynamic alterations can be a result of?

- shock
- hemorrhage
- anesthesia induced hypotension

98

Ischemic Heart Diseases that are Non-Atherosclerotic ?

- Lupus
- Traumatic injury
- Kawasaki Disease
- Cocaine-Induced Vasospasm

99

Treatments of CAD

- Clot dissolving drugs
- Shock for fibrillation
- IABP
- Angioplasty / Stents
- Coronary Bypass on CPB or Op-CAB
- Cardiomyoplasty
- Heart Transplant

100

CAD patients tend to be

Hypovolemic with increased SVR

101

CPB Considerations: Hypovolemia

When anesthesia removes vosoconstriction during induction, what is needed?
Keep track of how much crystalloid is given before bypass; check HCT just before going on CPB if concerned.

- Volume Expansion

102

The lower the EF (<40%), the greater the likelihood of the patient to be in CHF, therefore the patient may be ?

- Normal or hypervolemic

103

CPB Considerations: ECG

Be alert for any ectopic or Eschemic changes. When going on CPB, be especially observant for

- ST Elevations
- Bradycardia (no vent yet)
- PA Pressures

104

The change from pusitile pressure to non - pulsitile pressure decreases the following:

- ABP
- hemodilution
- Cooling
- Surgical manipulation

Increase flow and pressure to optimize flow to coronaries.

105

With myocardial protection in mind what should be considered with a patient that has AI?

Should retrograde carioplegia be considered ?

- Suction with LV Vent

- Depends on the extent and location of legions.

106

Why is the time during cross-clamp removal so critical ?

- We want to prevent distention of the heart

107

Mortality risk of a redo CABG?

10%

108

Risk of entering a patant IMA graft during sternotomy approaches what percentile?

50%

109

Blood flow in muscles during strenuous exercise can increase by how much ?

20-fold

110

Rate of blood flow through the muscles is ?

Intermittent during contraction due to mechanical compression of the vessels.

111

Capillaries open (vasodilate) during exercise do to ?

Decreased O2 in the tissues.

112

Drop in Oxygen content in muscle tissues causes what ?

Local arteriolar dilation

113

Sympathetic vasoconstrictor nerves secrete

norepi

114

Adrenal glands secrete

norepi (a) and Epi (B)

115

Vasodilation is due to:

- ↓ O2 in the tissues
- Adenosine
- H+
- Lactic Acid
- CO2

116

Sympathetic vasoconstrictor nerves secrete the following?

Norepinephrine at their nerve endings

117

When the Sympathetic vasoconstrictor nerves are maximally activated, they can secrete enough norepinephrine to cause what?

Decrease in blood flow through the resting muscles to as little as 1/2 to 1/3 of the normal flow.

118

Mass Sympathetic discharge causes what ?

- Increase in Arterial Pressure
- Increase in C.O.

119

Increase in Arterial Pressure causes what ?

- Vasoconstriction of arterioles
- Increased contractility of the heart
- Increased filling pressures

120

During Mass Sympathetic discharge, the heart is stimulated which causes what?

- Increased HR
- Increased in contractility

121

During Mass Sympathetic discharge, the arterioles of the PVS are strongly contracted which causes what ?

- Active muscles are strongly dilated
- No vasoconstriction in coronary & cerebral circulation

122

During Mass Sympathetic discharge, the muscle walls of the veins are contracted which causes what ?

- Increase in venous return / preload

123

Increase in C.O. results mostly from

- Sympathetic stimulation