CVPR 312 Cardiac Pathophysiology / Lecture 2 / Ischemic Heart Disease Flashcards
1
Q
Ischemic Heart Disease (IHD) is Characterized by changes in the cardiac muscle that occur when ?
A
Coronary arterial oxygen supply is inadequate to meet myocardial metabolic demands.
2
Q
Coronary sinus SvO2 =
A
30%
3
Q
Inadequate blood supply (circulation) to a local area due to blockage of the blood vessels to the area.
A
Ischemia
4
Q
An oxygen deficiency in body tissues
A
Hypoxia
5
Q
Hypoxemia
A
Decreased PaO2
6
Q
Anoxia
A
Absence of oxygen
7
Q
Cyanosis
A
a bluish skin tint caused by inadequate oxygenation of the bloodstream.
8
Q
Myocardial Ischemia (MI) can be du to the following 2 things?
A
- Acute coronary thrombosis
- Coronary atherosclerosis
9
Q
Most Common cause of death in the industrialized world
A
- 500,000 die annually
- 12 million affected in US
10
Q
Risk Factors for Myocardial Ischemia
A
HTN DM Cigarette smoking Hyperlipidemia …Cholesterol (LDL) Obesity Sedentary lifestyle Psychological stress
11
Q
Most frequent cause of coronary blood flow and myocardial ischemia ?
A
Atheromatous plaque
12
Q
Coronary vasoconstriction / spasm Typically occurs at or near plaque and ?
A
damaged endothelium
13
Q
Coronary emboli often results from ?
A
thrombi from LV or prosthetic valves
14
Q
Severe hypotension
A
MAP < 45-55 mmHg = loss of coronary autoreg
15
Q
In the precence of CAD pressure even higher than ___ may be needed to prevent ischemia.
A
70 mmHg
16
Q
Causes of Myocardial Ischemia (cont.)
A
- Aortic Valve stenosis
- Hypertrophic cardiomyopathy
- Inflammatory dz of coronary arteries
- Congenital anomalies of the coronary circulation
- Extremely raid heart rate
17
Q
Imbalance between O2 Sypply & O2 demand
Predisposes patients to ?
A
- Myocardial ischemia
- Ventricular dysfunction
- Electrical Instability
- MI
- Possible death from dysrhythmias or heart failure
18
Q
At rest the myocardium extracts about ___________ of the O2 from coronary arterial blood
A
70-80%
19
Q
Consequently, any increased O2 demand must be met by
A
increases in blood flow
20
Q
In the myocardial oxygen supply - demand balance patients may develop myocardial ischemia if:
A
- ) Myocardial oxygen supply falls short of demand
2. ) Myocardial oxygen demand exceeds supply
21
Q
In regards to the coronary arterial blood supply, the
LEFT coronary artery supplies what?
A
Anterior & Lateral portions of the LV
22
Q
In regards to the coronary arterial blood supply, the
RIGHT coronary artery supplies what?
A
RV & posterior LV
80-90% of people
23
Q
% of Coronary venous blood that comes from the LV to the Coronary Sinus ?
A
75% of total
24
Q
From the RV to the > ________ > RA
A
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
