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Medicine: PBL wrap-ups > Unit 4 Case 3: Thoracic Aortic Aneurysm > Flashcards

Unit 4 Case 3: Thoracic Aortic Aneurysm Flashcards

1
Q

histology of blood vessels

A

tunica intima
tunica media
tunica adventitia

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2
Q

tunica intima

A

innermost
simple squamous flat cells with flat nuclei
sit on the basal lamina

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3
Q

tunica media

A

elastic circular smooth muscle

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4
Q

tunica adventitia

A

outermost
fibroblasts
longitudinal and smooth muscle
vaso vasorum

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5
Q

capillaries

A

endothelial cells
basement membrane and some pericytes
continuous: uninterrupted endothelium and reduced permeability
sinusodial: wider gaps for the movement of larger molecules/cells in the liver and the spleen
fenestrated: gap junctions allow the movement of fluid (real corpuscles)

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6
Q

types of arteries

A

muscular
elastic

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7
Q

muscular arteries

A

media is bound by internal and external elastic lamina

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8
Q

elastic arteries

A

within the media layer has concentric layers of elastic fibres and smooth muscles

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9
Q

lumen of arteries compared to veins

A

arteries are smaller

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10
Q

wall of arteries compared to veins

A

thicker in arteries

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11
Q

media layer in arteries compared to veins

A

thicker in arteries

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12
Q

adventitia layer in arteries compared to veins

A

thinner in arteries

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13
Q

other features arteries and veins have

A

arteries have internal and external elastic lamina
veins have valves

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14
Q

how does the histology of vessels differ in the presence of an aneurysm

A

affects all layers of the vessel wall
degradation of extracellular elastin and collagen fibres
meidal degeneration
medial and adventitial infiltration by mononuclear lymphocytes and macrophages forming vascular associated lymphoid tissue
thickening of the vasa vasorum
vessel wall is weakened so the lumen is widened

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15
Q

what occurs in the media of vessels during aneurysms

A

SMCs clonal expand and change to more phagocytic like phenotypes
MMP activity increases causing further aortic wall degradation and dilation

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16
Q

what is laplaces law

A

the large the vessel radius the greater the wall tension required to withstand the given internal fluid pressure

P= (w/r) x T
p= inward pressure of the artery from the vessel wall
T= tensional stress within the wall of the vessel
W= thickness of the artery wall

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17
Q

relationship between inward pressure and tensional stress and radius of the wall

A

inward pressure exerted by the vessel wall on the blood is directly proportional to the tensional stress in the wall and inversely proportional to the radius of the wall

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18
Q

large thin walled vessels pressure

A

they are low pressure
e.g. veins

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19
Q

larger the radius the what

A

greater the tension

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20
Q

why can capillaries withstand larger pressures

A

due to their small diameter

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21
Q

what is in the image and why

A

elastic artery
elastic fibres appear black

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22
Q

what is shown by the yellow arrows

A

the adventitia of the vein

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23
Q

what is shown by the black arrows

A

external elastic lamina

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24
Q

what are the different categories for beta blockers

A

1st generation
2nd generation
3rd generation

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25
Q

1st generation beta blockers

A

non selective
block beta 1 and beta 2 receptors n the heart
based on the blockade of beta 1 receptors, decreased heart rate and reduces contractility
treat hypertension angina
beta 2 receptors are predominant in the lungs so the blockade can lead to bronchoconstriction
not recommended in asthma

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26
Q

examples of 1st generation beta blockers

A

propranolol
pindolol
nadolol
solatol
timolol

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27
Q

2nd generation beta blockers

A

beta 1 selective
cardio selective
chronic diseases
at high enough doses can be lost and beta 2 receptor blockade may occur

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28
Q

examples of 2nd generation beta blockers

A

atenolol
acebutolol
bisoprolol
esmolol
metoprolol

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29
Q

3rd generation beta blockers

A

non selective and selective
act on blood vessels to cause vasodilation

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30
Q

carvedilol and labetalol

A

non selective
cause vasodilation by blocking alpha and beta q

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31
Q

nebivolol

A

beta 1 selective and released nitrous oxides from endothelial cells

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32
Q

betaxolol

A

vasodilation by blocking calcium channels

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33
Q

side effects of beta blockers

A

tiredness
dizziness]lightheaded
cold fingers or toes
difficulty sleeping/nightmares
nausea

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34
Q

emergency side effects of beta blockers

A

shortness of breath
wheezing
tightening of chest
yellow skin
whites of eyes turn yellow

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35
Q

beta blockers used in aneurysms

A

proanalol
lower blood pressure by slowing the heart rate
may reduce how fast the aorta is widening

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36
Q

marfan syndrome

A

disorder of the body’s connective tissue
autosomal dominant hereditary condition
gene leads to abnormal fibrillar production

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37
Q

what is an aneurysm

A

budge in the wall of an artery
caused by constant high blood pressure, wearing the arteries

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38
Q

different types of aneurysms

A

abdominal aortic
thoracic aortic
cerebral

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39
Q

abdominal aortic aneurysms

A

most dangerous type
aorta is the largest vessel in the body
most common

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40
Q

thoracic aortic aneurysm

A

largely asymptomatic
may get back pain and shortness of breath if symptoms do occur

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41
Q

cerebral aneurysm

A

brain
not too dangerous unless they rupture causing a bleed on the brain

42
Q

risk factors for aneurysms

A

high blood pressure
smoking
family history
age
gender
genetic conditions

43
Q

high blood pressure as a risk factor

A

places increased pressure on the walls off the artery increasing the chances of an aneurysm

44
Q

smoking as a risk factor

A

harmful substances in tobaccos smoke can damage the walls of the blood vessels

45
Q

age as a risk factor

A

normally around age 40

46
Q

gender as a risk factor

A

women are more likely to develop
after menopause women have less oestrogen in their blood which helps with the elasticity of blood vessels

47
Q

genetic link as a risk factor

A

having a close relative that has aneurysms will increase your own chances

48
Q

genetic conditions as a risk factor

A

marfan syndrome
genetic condition that affects the connective tissue of the body will weaken the wall of the aorta

49
Q

aortic rupture

A

the all layers of the aorta wall tear
causing blood to leak out of the aorta due to the burst aneurysm
stops blood being pumped around the body and is life threatening

50
Q

aortic dissection

A

starts with a tear in the inner layer of the aortic wall of the thoracic aorta

51
Q

stage 1 of the response to internal bleeding

A

hypovalemia and cardiovascular compensation

52
Q

osmoreceptor response to internal bleeding

A

osmolality of the remaining fluid hasn’t yet changed
osmoreceptors are ignorant of the volume reduction
vasopressin release is triggered by baroreceptors sensing loss of blood pressure

53
Q

categories of cardiovascular response to haemorrhage

A

autonomic effects
neurohormonal effects

54
Q

autonomic effects in the response to haemorrhage

A

arterial hypotension causes baroreflex activation
decreased cardiac output causes chemoreceptor activation
decreased vagal stimulus, increased heart rate
sympathetic activation which results in:
-increased peripheral vascular resistance
-redistribution of blood flow away from the cutaneous and splanchnic circulariotn
-stimulation of systemic catecholamine release from adrenal glands producing increased systemic effect in addition to peripheral sympathetic nervous system of solitary tract to hypothalamus
-stimulation of renin by sympathetic stimulation of the juxtaglomeraluar cells due to lower renal perfusion

55
Q

what causes baroreflex activation

A

arterial hypotension

56
Q

what causes chemoreceptor activation

A

decreased cardiac output

57
Q

neurohormonal effects to haemorrhage

A

renin secretion causes: vasoconstriction by angiotensin and increased sodium retention by aldosterone

vasopressin release causes:
vasoconstriction by V1 receptors and increased water retention by V2 receptors

venous hypotension decreases atrial natriuretic peptide secretion causing:
decreased renal blood flow and decreased urinary water and sodium excretion

net effect is decreased urine output and increased retention of sodium and water

58
Q

what does renin secretion cause

A

vasoconstriction by angiotensin
increased sodium retention by aldosterone

59
Q

what does vasopressin release cause

A

vasoconstriction by V1 receptors
increased water retention by V2 receptors

60
Q

what restores intravascular volume

A

transcapillary refill

61
Q

transcapillary refill

A

movement of fluid and protein (mainly albumin) from interstitial compartment into the intravascular compartments

62
Q

what describes the net movement of fluid in the capillaries

A

the starling equation

63
Q

what does the sympathetic response to haemorrhage result in

A

decrease in diameter of the arterioles and decrease in pressure at capillaries

64
Q

oncotic pressure after haemorrhage

A

remains same
as the fluid composition of the intravascular component is unchanged
no longer balanced by high capillary hydrostatic pressure
results in movement of free tea out of the interstitial space and into the intravascular space

65
Q

albumin movement

A

after movement of free water the capillary fluid is diluted
hydrostatic attraction into the capillary is balanced by the osmotic attraction out of the capillary
protein concentration gradient appears to be related to volume of interstitial compartment and pressure within it
interstitial albumin replenishes the intravascular albumin deficit
haemorrhage stimulates albumin synthesis by the liver

66
Q

compensatory mechanism

A

reduction in blood volume during acute blood loss causes a fall in central venous pressure and cardiac filling
leads to reduced cardiac output and arterial pressure

67
Q

what are examples of the body’s compensatory mechanisms

A

baroreceptor reflexes
chemoreceptor reflexes
circulating vasoconstrictors
renal absorption of sodium and water
activation of thirst mechanisms
reabsorption of tissue fluids

68
Q

cariogenic shock

A

impaired coronary blood flow resulting from hypotension causes myocardial hypoxia and acidosis
depresses cardiac function and causes arrythmias

69
Q

sympathetic escape

A

Accumulation of tissue metabolic vasodilator substances impairs sympathetic-mediated vasoconstriction, which leads to loss of vascular tone, progressive hypotension and organ hypoperfusion
Loss of precapillary vascular tone increases capillary hydrostatic pressure and capillary fluid filtration, which reduces plasma volume

70
Q

Cerebral ischemia/hypoxia

A

Loss of sympathetic outflow from a hypoxic medulla leads to vasodilation, which further reduces arterial pressure and cerebral perfusion

71
Q

Metabolic acidosis

A

acidosis depresses cardiac muscle and vascular smooth muscle contraction, which further decreases arterial pressure

72
Q

Rheological factors

A

Reduced microcirculatory flow
increases tissue blood viscocity reduces perfusion
Plugging of the microcirculation by leukocytes and platelets, and intravascular coagulation reduce organ perfusion

73
Q

Systemic inflammatory response

A

Endotoxins released into systemic circulation from the ischemic gastrointestinal tract lead to cytokine production, and enhanced formation of nitric oxide and oxygen free radicals, which cause vasodilation, cardiac depression, and organ injury

74
Q

hypovolemic shock

A

occurs when the body starts to shut down due to large amount of fluid loss

75
Q

haemorrhage shock

A

type of hypovolemic shock
where the fluid lost is blood

76
Q

classes of haemorrhage shock

A

Class 1 – blood loss < 15% of total blood volume (up to 750mL of blood lost)​
Class 2 - blood loss is 15-30% of total blood volume (750-1500 mL of blood lost)​
Class 3 – blood loss is 30-40% of total blood volume (1500-2000 mL of blood lost)​
Class 4 – blood loss > 40% (more than 2000 mL of blood lost)

77
Q

what is involved in initial haemorrhage shock resuscitation

A

primary survey, circulation
insert 2 large-bore IVs for fastest fluid administration
administer 20mL/kg bolus of normal saline
transfuse blood products at a 1:1:1 ratio

78
Q

how are TAAs diagnosed

A

CT
MRIU
X ray

79
Q

what does the image show

A

Ct scan with an iodine contrast
black arrow is an aneurysm of descending aorta
white arrow shows blood in the throat as a result of the aortic dissection

80
Q

chest x ray and aneurysms

A

demonstrates widening mediastinum
not sensitive enough to diagnose
CT required for more detailed imaging

81
Q

surgical processes used in the case

A

aortic root surgery
end-vascular aortic aneurysm repair
emergency surgery

82
Q

aortic root surgery

A

Open-chest surgery to treat and enlarged section of the aorta to prevent a rupture. Aortic aneurysms near the aortic root may be related to Marfan and other related condition. ​
Asurgeon removes part of the aorta and sometimes the aortic valve. A graft replaces the removed section of the aorta and a mechanical or biological valve. If the valve is not removed, the surgery is called valve-sparing aortic root repair. ​
​

83
Q

end vascular aortic aneurysm repair

A

catheter inserted into blood vessel
graft attached at the end and placed at the site of the aneurysm
reinforces the weakened section

84
Q

emergency surgery

A

ruptured TAA requires emergency open chest surgery
risky and high chance of complications
important to treat TAAs before rupturing

85
Q

difference between surgeries for ascending and descending aneurysm

A

Median sternotomy for ascending and aortic arch aneurysms or left thoractotomy or thoraco-retroperitoneal exposure for descending and thoracoabdominal aneurysms) and replacement with a synthetic graft.

86
Q

when is elective surgery indicated for aneurysms

A

Large in the case the diameter was 61mm which is large.​
Rapidly enlarging (> 0.5 cm/year)​
Causing bronchial compression​
Causing aortobronchial or aortoesophageal fistulas(abnormal tunnel in the body)​
Symptomatic ​
Traumatic ​
Mycotic(infection with a fungus or a disease caused by a fungus.)

87
Q

complications of open heart surgery

A

Bleeding.​
Death.​
Heart attack due to a blood clot after surgery.​
Infection at the site of the chest wound.​
Long-term need for a breathing machine.​
Irregular heart rhythms, called arrhythmias.​
Kidney problems.​
Memory loss or trouble thinking clearly, which often is temporary.​
Stroke.

88
Q

less invasive options for aneurysm treatment

A

transcatheter-placed end-vascular stent grafts
end-vascular surgery

89
Q

complications of TAA

A

rupture of aorta
aorta dissection

these may lead to death

90
Q

delayed mobilisation after surgery

A

associated with higher short term readmission and mortality

91
Q

early mobilisation after surgery

A

reduces risk of post operative complications
accelerates recovery of function walking capacity
reduces length of hospital stay

92
Q

positive impacts of early mobilisation post op

A

prevents blood clots
increased wound healing due to increased circulation
decreased gas and constipation
increased mood
prevents muscle weakness

93
Q

prevalence

A

number of individuals with the disease either at the specific point in time or over a specific period of time

94
Q

incidence

A

number of new cases of disease during a specified period

95
Q

mortality

A

related to the number of deaths caused by health event under investigation

96
Q

role of an agency carer

A

provide domestic care
no nursing care

97
Q

carer assessment

A

provided to individuals who care for someone to see what would make their lives easier
may be eligible for support

98
Q

psychological impact of being a full time carer

A

stress and worry
anxiety
isolated and lonely
less time for yourself
financial worries
lack of sleep
guilt frustration and anger
low self esteem
depression
physical impact

99
Q

fear of surgery

A

homophobia
where symptoms involve irrational fear, situational induced panic attacks

100
Q

acute stress

A

anxiety disorder develops in weeks after traumatic event
lasts at least 3 days
up to a month

101
Q

symptoms of acute stress

A

feeling numb
detached
experiencing derealisation
depersonalisation

102
Q

treatment of acute stress

A

psychiatric evaluation
medication such as antidepressants

Medicine: PBL wrap-ups (21 decks)

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