Vascular Surgery & Hypertension Flashcards
1
Q
What “branches” off of the ascending aorta?
A
Coronary arteries
2
Q
What are the branches off of the aortic arch?
A
Innominate artery/brachiocephalic
Left common carotid
Left subclavian
3
Q
What branches come off of the brachiocephalic?
A
Right subclavian
Right common carotid
4
Q
Why should an arterial line always be placed in the right arm during a mediastinoscopy?
A
If the aorta is compressed during mediastinoscopy, the first vessel affected would be the innominate so monitoring a-line in the right arm would monitor perfusion
5
Q
How is monitoring with an A-line in the right arm also a monitor of brain perfusion during a mediastinoscopy?
A
This also monitors perfusion to the brain because the right carotid comes off the innominate
6
Q
What determines where the A-line is placed for an ascending aortic aneurysm?
A
Location of the surgeon’s cross-clamp
-surgeon may put in a femoral line
7
Q
What can an asceding aortic aneurysm also affect?
A
The aortic valve
8
Q
What diseases are aortic dissections associated with?
A
Marfan’s
Hypertension
9
Q
Where are traumatic aortic dissections more common?
A
In the ascending aorta
10
Q
Where are aortic aneurysms more common?
A
In the abdominal aorta
11
Q
Where is aortic occlusive disease more common?
A
At aortic bifurcation
12
Q
What medication is required with aortic cross clamping?
A
Heparinization
13
Q
What besides blood can anesthesia give to prevent clot breakdown?
A
Antifibrolytics
14
Q
What does an aortic cross clamp do to afterload?
A
Increases afterload
15
Q
The increased afterload due to aortic cross clamping can have what negative effects on the heart?
A
Increases LV pressure required may > LV failure
Increases O2 demand > ischemia
16
Q
What device is common to use during aortic cross clamping in order to monitor afterload and the heart’s response to this increase?
A
PA catheter
17
Q
What vasodilator is used during aortic cross clamping in order to help decrease resistance?
A
NTG
18
Q
Why is an arterial dilator (Nipride) not used in aortic cross clamping in order to decrease afterload?
A
May decrease spinal cord perfusion pressure by both decreasing distal aortic pressure and increasing CSF pressure
19
Q
What does anesthesia want to give before cross clamp is removed? Why?
A
Volume
Because when the clamp is removed there is a sudden drop in afterload
20
Q
What happens when the cross clamp is removed?
A
Sudden drop in afterload > hypotension
-turn NTG off
21
Q
What is a risk with all surgeries that invovles aortic cross clamping?
A
Acute kidney injury
22
Q
What increases the risk of kideny injury with aortic cross clamping?
A
longer cross clamping times
emergency surgery
pre-existing renal disease
23
Q
What kidney injury prevention attempts have been tried, none of which are successful?
A
Mannitol
Furosemide
Fendolopam
Dopamine
24
Q
What makes ascending aorta repairs more risky?
A
Disscetions or tears can extend back into valve
- surgery is similar to AVR but:
- longer surgery time
- more blood loss
25
What is circulatory arrest? When is it utilized?
Surgical technique that involves deep hypothermia and stopping circulation
Ascending aortic repairs
26
Why is circulatory arrest utilized in ascending aorta dissections or tears?
Perfusion is difficult even with CPB, profound hypothermia decreases metabolism and reduce risk of ischemia
27
What is unique about descending aorta incision and ansethesia?
Thoracolumar incision and one lung anesthesia
| -sternotomy can be done if needed
28
Why is one lung ansethesia performed during descending aorta repair?
Makes more room for surgeon to work
29
Where are aoritc clamps placed during descending aortic repair?
Above and below the site
30
What does cross clamping above and below the descending aortic repair do to circulation?
Circulation is isolated into 2 separate systems
- femoral cannulation for CBP of lower body
- upper body perfusion via heart and lungs
31
What risk does double cross clamping the descending aorta carry?
Paraplegia due to inadequate spinal cord perfusion
32
Why is paraplegia a risk with descending aorta repair surgery?
The main radicular artery that perfuses the spinal cord is the Artery of Adamkiewicz, it's location varies among the population, so it is unknown if it is affected by clamp until postop
33
What percetage of the population have the artery of adamkiewicz coming off T5-T8?
15%
34
What percetage of the population have the artery of adamkiewicz coming off T9-T12?
60%
35
What percetage of the population have the artery of adamkiewicz coming off L1-L2?
25%
36
How can anesthesia help protect the spinal cord during descending aorta repair?
```
Steroids
Hypothermia
Mannitol
Lumbar CSF drainage
Avoid excessive vasodilator administration with cross clamp afterload elevation
```
37
How does removing some lumbar CSF help protect the spinal cord?
Decreases CSF pressure > less tissue pressure for vascular to push against and get spinal cord perfused
38
Where is an infrarenal cross clamp of the aorta? Does this risk renal failure?
Below the kidneys
| Yes
39
Where is a suprarenal cross clamp of the aorta? Does this risk renal failure?
Above the kidneys
| Yes
40
What less invasive technique for repairing dissection or aneurysm removes the need for aortic cross clamping?
Endovascular stents
41
Where can endovascular stenting be used in aortic repairs?
Anywhere
42
What could be suspected in a person with peripheral vascular disease from plaque?
They are prone to plaque, so it is reasonable to suspect there may be plaque in the coronaries and/or carotids
43
Lower extremity peripheral vacular bypass graft procedures done with regional anesthesia have what benefits for the graft?
Increase graft flow and decrease graft thrombosis
44
Peripheral vascular surgeries for bypass
Femoral popliteal bypass
Femoral to femoral bypass
Aorta bi-femoral bypass
45
Hypertension does what to vascular tone?
Causes chronic vasoconstriction
46
What does this chronic vasoconstriction mean for volume status?
Chronic volume depletion due to less vascular space for fluid
47
What used to treat hypertension also affects chronic volume depletion?
Diuretics
48
What happens to the kidney with chronic volume depletion from volume depletion and/or chronic constriction of the renal vasculature?
Kidneys are under perfused
49
What response do the kidney have due to under perfusion?
Triggers renin, angiotensin, aldosterone
50
What overall effect does the trigger of RAAS have?
Retain fluid in an attempt to increase renal blood flow
51
What diseases are associated with hypertension?
CAD
PVD
Carotid disease
Renal dysfunction
52
How does hypertension affect autoregulation?
It shifts the autoregulation curve to the right
53
What does a right shift in the autoregulation curve mean?
The range for autoregulation function is higher
| -patients needs a higher BP to maintain autoregulation
54
What are the advantages of continuing BP medications preop?
No rebound hypertension
-more stable BP, less labile
Less angina/ischemia
Lower morbidity and complications
55
What is the DBP "red flag" value for HTN and that May case should be postponed?
110 mmHg
| -consider postponement if elective procedure
56
Why is continued preop use of ACE inhibitors and ARBs controversial?
```
Possible refractory hypotension under anesthesia when continued
-only class that is sometimes held
```
57
What benefits does continuing beta blockers preop have?
Smoother induction
| -consider additional dose
58
Should BB be given preop to those not on them?
Risks out weigh benefits
- Fewer MIs and arrhythmias
- More strokes and deaths
59
What do all calcium channel blockers cause?
Myocardial depression
| -so does VA and BB
60
What can be given for a coronary vasospasm?
Calcium channel blocker
61
What happens in a HTN patient during induction (BP wise)?
Labile BP
- induction agent vasodilates them > hypotension
- stimulation > HTN
62
What makes lability of BP worse in HTN patients?
If they are volume depleted
63
With poor preop control of BP what are they at higher risk for?
Ischemia
64
What also increases the risk of ischemia?
Hypotension
| -HTN is better than hypotension
65
What helps reduce the labile BP swings?
```
Fluid
Induction-adequate depth
-fentanyl
-lidocaine
Adjunct BB dose or sodium nitroprusside
```
66
What is the danger of hypotension in a HTN patient?
Poor organ perfusion
| -autoregulated orgran now require higher BP to maintain perfusion
67
Why is hypertension a significant cause of congestive heart failure and cardiomyopathy?
Nagelhout
Because it causes increased afterload from chronic vasoconstriction
68
Hypertension increases the likelihood of the development of what?
Atherosclerosis
| -and thus chronic and untreated HTN increases risk of MI, stroke and chronic kidney injury
69
What is essential hypertension?
AKA primary and idiopathic
- has no identifiable cause
- diagnosed on the basis of exclusion
70
What is remedial hypertension?
AKA secondary hypertension
| -has an identifiable and potentially curable cause
71
What is concentric hypertrophy?
Hypertrophy that occurs in response to chronic increases in intracardiac pressures
- Chronic HTN and increased afterload > hypertrophy of LV
72
Does LV hypertrophy affect the O2 supply and demand balance?
Yes, it increases demand
73
All patients with chronic HTN should be suspected of having?
Some degree of coronary artery disease
74
What medications have been found to help with refractory hypotension from ACE inhibitors and ARBs?
Vasopressin and methylene blue
75
Patient with DBP great than what have a significantly increased risk of perioperative cardiac morbidity?
110 mmHg
-may be modified in patients with HTN in whom DBPs greater than 110 occur frequently despite aggressive antihypertensive therapy
76
Why may Etomidate offer some advantages in patients with cardiac pathology as compared to Propofol?
Etomidate preserves SV and CO
77
Intraluminal stent grafts have been approved for aneurysms of what size?
Co-existing
Above 5.5 cm
| -as well as complicated type B dissections
78
Chronic impairment of blood flow to the extremities is most often due to what?
Atherosclerosis
79
Acute arterial occlusion is mostly likely from?
Embolism
80
What is an ankle-brachial index? (ABI)
The calculated ratio of SBP at the ankle to the SBP in the brachial artery
81
What does the ABI define?
An ABI of less than 0.9 is the most widely accepted definition of peripheral arterial insufficiency
82
Why does intermittent claudication occur with peripheral arterial disease?
When the metabolic requirement of exercising skeletal muscles exceeds oxygen delivery
83
Why does rest pain occur with peripheral artery disease?
The arterial blood supply does not even meet the minimal nutritional requirements of the affected extremity
84
What are the risk factors associated with development of peripheral atherosclerosis?
```
Older age
Family Hx
Smoking
DM
HTN
Obesity
Dyslipidemia
```
85
What are the most reliable physical findings associated with PAD?
Decreased or absent arterial pulses
| -buits may indicate the anatomical site of arterial stenosis
86
Signs of chronic leg ischemia?
```
SQ atrophy
Hair loss
Coolness
Pallor
Cyanosis
Dependent redness
```
87
Reduced lower extremity pulses may be the presenting sign of what (less commonly)?
Undiagnosed aortic coarctation
88
What is an aortic dissection?
M and M
An intimal tear that allows blood to track into the aortic wall (the media)
89
Who diseases put patient at risk of aortic dissection?
Marian syndrome and Ehlers-Danlos syndrome > cystic medial necrosis > aortic dissection
90
What aortic dissections are most common?
Proximal type involving the ascending aorta
91
Where do aortic aneurysms more commonly occur?
In the abdominal vs thoracic aorta
92
What is the most common cause of aortic aneurysms?
Atherosclerosis
93
What is a pseudoaneurysm?
When the intima and media are ruptured and only adventitia or blood clot forms the outer layer
94
When is elective treatment of aortic aneurysms generally performed?
With aneurysms 5 cm or greater
95
Where does atherosclerotic obliteration of the aorta (Occlusive disease of the aorta) most commonly occur?
Near the aortic bifurcation
| -Leriche syndrome
96
What is coarctation of the aorta?
A congenital narrowing of the aorta
97
What is preductal (infantile) type coarctation of the aorta?
Lesion is proximal to the opening of the ductus arteriosis
| -recognized in infancy because lower extremities are cyanotic
98
What is postductal coarctation of the aorta?
Lesion is after the ductus arteriosus
- may not be recognized until adulthood
- symptoms and hemodynamic significance depend on severity of narrowing and the extent of collateral circulation
- HTN in the upper body is usually present
- “rib notching” on CXR may be present d/t dilated collateral intercostal arteries
99
What aortic procedures are usually performed with median sternotomy, CPB and deep hypothermic circulatory arrest?
Surgery on the ascending aorta
| Surgery on the aortic arch
100
This aortic surgery may be complicated by long aortic cross clamp times and large intraoperative blood loss?
Ascending aorta
101
What aortic surgery can be performed with a left thoracotomy with or without CPB?
Surgery involving the descending thoracic aorta
102
Surgery on the descending thoracic aorta involves cross clamping the aorta above and below the lesion, what does this do to BP?
Acute hypertension develops above the clamp and hypotension below (when there is no shunt or partial bypass)
103
During surgery involving the descending thoracic aorta, when is the period of greatest hemodynamic instability?
Following the release of the aortic cross clamp
-abrupt decrease in afterload together with bleeding and release of vasodilation acid metabolites from the ischemic lower body can precipitate severe hypotension
104
Spinal cord perfusion pressure =
MAP - CSF pressure
105
In general, the more distally the clamp is applied to the aorta what affect does this have on LV afterload
The more distally the clamp is placed the less effect on LV afterload
