7. Aortic Surgery- Exam 2 PERF TECH Flashcards
(130 cards)
1
Q
what is the goal of aortic surgery
A
enable aortic repair while limiting ischemic injury to the CNS
2
Q
what are 4 different strategies for aortic surgery
A
ascending
arch
thoracic
descending
3
Q
what are the 2 types of aortic conditions
A
aneurysms
dissections
4
Q
ascending aorta=
A
begins at the AV annulus and extends to the proximal innominate artery
5
Q
transverse arch=
A
where 3 brachiocephalic branches arise
6
Q
which 2 aortic surgery treatments are similar
A
treatment of ascending and transverse arch
7
Q
descending thoracic and thoracoabdominal aorta=
A
lies just beyond the subclavian tot he aortoiliac bifurcation
8
Q
when does a dissection occur? what does it create?
A
occurs when blood penetrates the intima of the aorta
creates an expanding hematoma btwn medial layers
9
Q
with a dissection, is the true lumen dilated?
A
true lumen is not usually dilated- its compressed by the dissection–branching vessels may not be affected
10
Q
an aneurysm includes dilation of what
A
all 3 layers
11
Q
what is the incidence of dissections and what does this result in
A
occurs in 3.2 dissections per 100,000 autopsies
results in more deaths than aneurysm rupture
12
Q
what are risk factors for a dissection
A
hypertension advanced age male sex Marfans Syndrome Coarctation Bicuspid AV Pregnancy
13
Q
what are causes/inciting events for dissections
A
increased physical activity
emotional stress
blunt trauma
–can also occur with or without any physical stress (cannulation for bypass)
14
Q
what is the mechanism for an aortic dissection:
1. Intimal Tear
A
- Presence of a weakened aortic wall
- Areas experiencing greatest mechanical shear forces
- Points where aortic is fixed, there is increased shear stress applied to the aortic wall
15
Q
% chance for having an intimal tear in the ascending
A
61%
16
Q
% chance for having an intimal tear in the descending
A
24%
17
Q
% chance for having an intimal tear in the isthmus (distal to the left subclavian)
A
16%
18
Q
% chance for having an intimal tear in the arch
A
9%
19
Q
% chance for having an intimal tear in the abdominal
A
3%
20
Q
what is the mechanism for an aortic dissection:
2. Propagation
A
- occurs within seconds
- driven by pulse pressure and ejection velocity
- origin of arteries (including coronaries) may be involved in aortic dissections
- vessel occlusion can also occur
- due to compression by false lumen
21
Q
DeBakey Type 1:
A
Intimal Tear: Ascending Aorta
Dissection: All parts of the thoracic aorta (ascending, arch and descending)
22
Q
DeBakey Type 2:
A
Intimal Tear: Ascending Aorta
Dissection: Ascending Aorta only- stops before the innominate artert
23
Q
DeBakey Type 3A:
A
Intimal Tear: Descending Aorta
Dissection: Descending Thoracic only distal to left subclavian, ends above diaphragm
24
Q
DeBakey Type 3B:
A
Intimal Tear: Descending Aorta
Dissection: below diaphragm
25
Stanford Type A:
- Ascending Aorta
- Any involvement regardless of where tear is and how far it propagates
- Usually emergent/urgent cases/more virulent cases
26
Stanford Type B:
- Distal Aorta
| - Any part of aorta distal to left subclavian
27
what is the prognosis for untreated ascending dissection- 2 day mortality and 3 month?
2 day mortality= 50%
| 3 month mortality= 90%
28
what is the usual cause of death for dissections
rupture of false lumen into the pleural space or pericardium
29
what types of dissection have a low incidence rate
debakey type 3
| stanford type B
30
what are 4 other causes of death after an aortic dissection
- progressive heart failure (AV involvement)
- MI (coronary involvement)
- Stroke (occlusion of cerebral vessels)
- Bowel Gangrene (Mesenteric artery occlusion)
31
what is the surgical mortality of aortic dissections? what type is the highest and which is the lowest
3-24% -depends on affected section of the aorta
highest mortality= aortic arch
lowest mortality= descending thoracic
32
what is the incidence of thoracic aneurysms
460 per 100,000
33
% of aneurysms involved with the ascending aorta
45%
34
% of aneurysms involved with the arch
10%
35
% of aneurysms involved with the descending aorta
35%
36
% of aneurysms involved with the thoracoabdominal
10%
37
aneurysms shape: fusiform
entire circumference of the aortic wall
38
aneurysm shape: saccular
involves only part of the circumference of the aortic wall
39
arch aneurysms are typically what shape
saccular
40
what is the crawford classification of aneurysms used to classify and describe
classify thoracoabdominal aortic aneurysms
| describe the extent of the aorta requiring replacement
41
Crawford extent 1=
involves most or all of the descending thoracic aorta and upper abdominal aorta
42
Crawford extent 2=
involves most or all of descending thoracic aorta and extends into infrarenal abdominal aorta
43
Crawford extent 3=
involves the distal half or less of the descending thoracic aorta and varying portion of the abdominal aorta
44
Crawford extent 4=
involves most or all of the abdominal aorta
45
how many aneurysms rupture
more than half
46
what is the untreated 5 year survival of a thoracoabdominal aortic aneurysm
13-39%
47
what are 3 other complications of aneurysms
mycotic infection
atheroembolisation
dissection (rare)
48
what are 3 predictors of a poor prognosis of aneurysms
1. large size (less than 10cm max transverse diameter)
2. Presence of other symptoms
3. Associated CV disease (CAD, MI, CVA)
49
majority of thoracic artery tears occur after what
trauma
- involve deceleraton injury (MVA)
- large shear stress on points of aortic wall that are relatively immobile
50
what does a thoracic artery tear from trauma lead to
immediate exsanguination and death
10-15% are lucky-survive to emergency care
-maintain the integrity of the adventitial covering of the aortic lumen
51
what is the most common site for thoracic artery rupture
most occur distal to the origin of the left subclavian artery
-due to fixeation at the point of the ligamentum arteriosum
52
what is the 2nd most common site for thoracic artery rupture
ascending aorta just distal to the aortic valve
53
diagnosis of dissections
dramatic onset
54
diagnosis of aneurysms
- asymptomatic until late in course
| - medical evaluation for unrelated problem or complication of aneurysm
55
what are the indications for surgery of the ascending aorta for a dissection
Acute Type A
- Virulent course
- High Mortaility
56
what are the indications for surgery of the ascending aorta for an aneurysm
- Persistent pain despite small aneurysm
- AV involvement creating a MI
- Rapidly expanding
- Greater than 5-5.5 cm diameter
- Angina
57
what are the indications for surgery of the arch for a dissection
Acute, limited to arch (rare)
58
what are the indications for surgery of the arch for an aneurysm
- Repair of arch aneurysm is more complicated (increased mortality)
- Persistent symptoms
- Greater than 5.5-6 cm
- Progressive expansion
59
what are the indications for surgery of the descending aorta for a dissection
- medical management in acute phase
- failure to control HTN medically
- continued pain
- enlargement on CXR, CT, Angio
- Neuro deficit
- Renal/GI ischemia
60
what are the indications for surgery of the descending aorta for an aneurysm
- Greater than 5-6 cm
- expanding/leaking
- chronic, causing persistent pain
61
what cases can you do CPB without circ arrest
Very proximal aneurysms limited to the Aortic Root or Ascending Aorta
62
CPB W/O CIRC ARREST: where do you cannulate
Cannulate in the ascending aorta or transverse aorta, and Dual stage in RA or Bicaval
--If patient is unstable prior to sternotomy – cannulate femoral to go on CPB prior to sternotomy
63
CPB W/O CIRC ARREst: where do you cross clamp
Cross clamp proximal to the Innominate Artery
64
CPB W/O CIRC ARREST- do you do normal LV/PA vent and plegia?
yes- normal case
65
Studies have shown it doesn’t necessarily abate cerebral metabolic demands because of what
Significant cerebral metabolic activity occurs at temperatures at which DHCA is initiated.
- Promotes brain ischemia
- Accumulation of metabolic wastes
66
1993 study by Svensson et al: Rates of TIA, Stroke, Early Mortality
low
67
1993 study by Svensson et al: results of Perioperative neurologic complications
Higher when DHCA was greater than 40 minutes
68
1993 study by Svensson et al: mortality results
Increased dramatically when DHCA was greater than 65 minutes
69
when was RCP first done? by who? to treat what?
1st done in 1980 by Milles and Ochsner
| -Treating massive air embolism
70
name 6 benefits of RCP
Homogeneous cerebral cooling
Air bubble wash out
Wash out of embolic debris
Wash out of metabolic wastes
Prevent cerebral blood cell micro aggregation
Delivery of oxygen and nutrients to brain
71
do experimental and clinical data consistently support the efficacy of RCP for cerebral protection? why?
NO
| Flow may not be adequate to meet the metabolic needs
72
is RCP or ACP the older technique
ACP
73
what technique maintained pre-DHCA jugular venous sats and cerebral oxygen extractioin
ACP
74
Study done by Olsson and Thelin conclusions
Unilateral ACP associated with higher risk of perioperative stroke than bilateral ACP
75
Study by Ye et al. looked at MRI perfusion imaging studies conclusions
- Porcine model
- Unilateral and bilateral ACP under DHCA
- Both provided uniform cerebral perfusion to both hemispheres
76
for a circ arrest case- where do you monitor temps
Nasopharyngeal / Bladder
Arterial
Venous
Water
77
for a circ arrest case- how do you monitor the brain
EEG
78
what dictates adequate cerebral cooling
Electrocerebral silence
79
for a circ arrest case- what drugs do you use
Mannitol (25g) and Steroids
- Enhances cerebral protection
- Put in the pump prior to turning off the pump (Prime?)
80
for a circ arrest case- what arterial cannulation site is preferred
Axillary Cannulation is preferred
81
for a circ arrest case- describe how axillary cannulation is performed
- Artery is usually exposed prior to sternotomy
- After heparin is given,
- 8mm graft is sewn to the artery
- Cannula is placed in the 8mm graft
82
for a circ arrest case-where do you cannulate arterially in an emergency
femoral artery
83
for a circ arrest case- in an emergent dissection case- what do you make sure of before going up to full flow
make sure that the cannula is in the true lumen!
84
for a circ arrest case- where do you put the venous cannula
RA, Bicaval, Femoral
| Depends on need and access
85
for a circ arrest case- when CPB is initated you assess adequacy of perfusion- this is especially important for what cannulation site
femoral artery
86
for a circ arrest case- 10°C drop in temperature – reduces rate of oxygen consumption by what %
50%
| As temperature decreases, metabolic demand decreases
87
for a circ arrest case- Pump flows can be reduced to a CI of?
1.6-1.8 L/min/m2
88
for a circ arrest case- A 10°C decrease in tempearture causes a ____% increase in blood viscosity
20-25%
89
for a circ arrest case- Hemodilution to a hct of less than __%. Why?
25%
-Before they used hemodilution, saw hypothermia-induced hyperviscosity which caused substantial morbidity (stroke and visceral infact)
90
for a circ arrest case- Hct kept low until you rewarm. Then you do what
Hemoconcentrate
91
for a circ arrest case- what are the effects of hemodiluting and having a low hct
- Reduces oxygen carrying capacity, but overall oxygen delivery improves
- Decreased viscosity enhances the flow in the microcirculation
92
for a circ arrest case- what do you do at fibrillation? Why this way?
Give CPG via retrograde cannula
| -Remember aneurysm/dissection is probably in the ascending aorta or arch, therefore no antegrade CPG.
93
for a circ arrest case- when can you give antegrade cpg
If the AV is competent and a AoXC can be safely put on the aorta w/o damaging tissue
94
for a circ arrest case- Keep cooling until EEG shows no cerebral electrical activity. How long does this take? what the brain temp? Cool no lower than what?
Usually takes about 20-25 min.
Brain Temp 18-20°C
Cool no lower than 15°C
95
for a circ arrest case- when you dont have an EEG, what do you do
cool for at least 25 min to a target core temp of 18-20°C
96
for a circ arrest case- at EEG silence, what do you do
Give pentobarbital
Circulate for 3 minutes
-Head is packed in ice to facilitate surface cooling
-Put patient in Trendelenburg position
97
for a circ arrest case- after the EEG is silent and you have given pentobarbital and circulated for 3 minutes- what happens next
Flow is turned off
Patient is drained
Innominate artery is snared
Initiate ACP
98
for a circ arrest case- Initiate ACP at what rate? where are the snares
10mL/kg/min
| Right axillary – innominate artery – snare diverts blood antegrade through right common carotid – brain.
99
for a circ arrest case- after ACP is given, the aorta is opened and you get bleed back/obstructed from what?
Bleed back from the L. Common Carotid and L. Subclavian obscure field view
- Cardiotomy suction in distal arch
- Possible use of balloon occluder in both vessels
100
for a circ arrest case- where is the end of the graft sewn
End of graft is sewn to proximal descending thoracic aorta, transverse arch or distal ascending aorta
-Attach head vessels: Island or Branched graft
101
for a circ arrest case- after the end of the graft is sewn, the patient is put in steep Trendelenburg- what happens next?
1. Cardiotomy suction placed in unattached graft
2. Release tourniquet on innominate
3. Slowly increase flow to full flow (50mL/kg/min) as the aorta and graft are deaired--If cannulated femorally, move the cannula to the arch
4. Systemic circulation re-estabilished
102
for a circ arrest case- when the Proximal graft is attached, you slowly rewarm to what temp? not to exceed what gradient
36.5°C
| Not to exceed a 10°C gradient between arterial blood and nasopharyngeal / bladder
103
for a circ arrest case- when the Proximal complete what happens
Deair with venting needle through graft
AoXC removed
TEE is utilized to make sure there is no air present
CPB is terminated
104
what off pump values do you want for:
| Systolic BP/Mean/HR/CI
Systolic BP appx 100-120mmHg
Mean 70-90mmHg
HR 60-80 BPM
CI 2.0-2.5 L/min/m2
105
what will you see after bypass, especially with DHCA
coagulopathy
106
why do you see coagulopathy after DHCA? what do you treat with?
Platelet dysfunction secondary to extreme hypothermia
- Usually requires FFP/ Platelets/ Cryo?
- Often resort to Factor VII and IX
- Usually use an antifibrinolytic to help with bleeding
107
COMPLICATIONS OF AORTIC SURGERY AND DHCA include what 8 things
```
Air Emboli
Clots
LV Dysfunction
MI (Reimplanting coronaries)
Renal Failure
Respiratory failure
Coagulopathy
Hemorrhage
```
108
TEVAR=
Thoracic EndoVascular Aortic Repair
- Requires femoral access
- Flouroscopy
- Graft self-deploys
- Req’s flouroscopy to check position
- Requires systemic heparinization
109
describe TEVAR proximal and distal ends
Requires proximal “Landing Zone” of 15mm length
| Distal end needs to be non-aneurysmal
110
Cons and considerations of TEVAR
Con: Side branches – possibility of occluding a vessel that branches off the aorta
Considerations: Aortic Tortuosity, calcification, atherosclerosis
111
TEVAR advantages
- Reduces mortality
- Reduces morbidity
- Less blood loss
- Quicker recovery
- Hemodynamic stability
- Pulmonary and cardiac comorbidities that may have not made them a candidate for open surgeries, allow them to have this option.
112
complications of TEVAR
```
Conversion to open procedure
Bleeding *most common
Endoleak
Stroke
Paraplegia
Contrast Nephropathy
```
113
with a TEVAR, why whould we have to Convert to open procedure
Aortic Rupture / dissection
| Malposition – causing visceral ischemia
114
with a TEVAR, describe the complication of an endoleak
- Blood flows back into the aneurysmal sac after the endovascular graft is placed
- Usually observe and hope it spontaneously resolves
115
describe left heart bypass
Heart pumps blood to the lungs
Lungs oxygenate
-Venous cannula places in LA/ L. Pulmonary veins
-Arterial cannula placed in descending aorta
116
when is left heart bypass used
Used on Descending legions
117
what is used in the ECC circuit for left heart bypass
- Tubing
- Centrifugal pump
- No Reservior
- No H/E
- No Bubble Trap
- Excluding those help minimize the heparinization required
118
with left heart bypass, If the patient needs volume, who gives it
Anesthesia
119
describe flow of blood with left heart bypass
Heart pumps blood to the vessels proximal to the clamp (usually the head vessels)
ECC pumps distal to clamp
120
where do you monitor arterial pressure while on left heart bypass
Monitored at radial or brachial artery (upper body)
| Monitored at femoral artery (lower body)
121
What the treatment?
Proximal Art Press= Increased
Distal Art Press= Decreased
Pulmonary Wedge Press= Decreased
Volume
| increase flow
122
What the treatment?
Proximal Art Press= Increased
Distal Art Press= Decreased
Pulmonary Wedge Press= Increased
increase flow
123
What the treatment?
Proximal Art Press= Increased
Distal Art Press= Increased
Pulmonary Wedge Press= Decreased
volume
| vasodilator
124
What the treatment?
Proximal Art Press= Increased
Distal Art Press= Increased
Pulmonary Wedge Press= Increased
vasodilator/diuretic
maintain flow
hold volume in a VR
125
What the treatment?
Proximal Art Press= Decreased
Distal Art Press= Decreased
Pulmonary Wedge Press= Decreased
volume
| look at partial occlusion of arterial outflow cannula
126
What the treatment?
Proximal Art Press= Decreased
Distal Art Press= Decreased
Pulmonary Wedge Press= Increased
inotrope
| increase flow
127
What the treatment?
Proximal Art Press= Decreased
Distal Art Press= Increased
Pulmonary Wedge Press= Increased
inotrope/diuretic
| decrease flow
128
What the treatment?
Proximal Art Press= Decreased
Distal Art Press= Increased
Pulmonary Wedge Press= Decreased
possible volume
| decrease flow
129
MARFAN’S SYNDROME=
Connective Tissue Disorder
They aren’t as stiff as they should be
Arteries are weakened, particularly the aorta
Aorta dilates – weakens
Under exertion the aorta can tear – dissection
Also have MV prolapse and AI
130
AORTIC DEBRANCHING AND ENDOVASCULAR REPAIR=
Can do an extra-anatomic bypass
- Connect the aorta to the Innominate artery, L. Carotid, and L. subclavian arteries
- Then, deploy an endograft in the arch and occlude the head vessels.
- Head vessels get flow via the graft, and the aneurysm/ dissection is treated via the endograft
