TOPIC 8 thoracic and AORTIC Surgery Flashcards
1
Q
Ascending Aorta: location
A
Begins at the AV annulus and extends to the
proximal innominate artery
2
Q
Transverse Arch: location
A
Where 3 brachiocephalic branches arise
3
Q
Are Treatment for Ascending and Transverse Arch are similar?
A
very similar
4
Q
More likely to see dissection or aneurism?
A
dissection?
5
Q
Descending Thoracic and Thoracoabdominal Aorta: Location?
A
Lies just beyond the subclavian to the aortoiliac bifurcation
6
Q
Dissection - what happens?
A
Occurs when blood penetrates the intima of the Aorta
Creates an expanding hematoma between medial layers
True lumen is not usually dilated
Compressed by dissection
Branching vessels may not be affected
7
Q
Aneurysm what happens
A
Dilation of all 3 layers
8
Q
Aortic Dissection Occurence?
A
Occurs in 3.2 dissections per 100,000 autopsies
Results in more deaths than aneurysm rupture
9
Q
Aortic Dissection Risk Factors? (7)
A
- Hypertension
- advanced age
- male sex
- Marfan’s Syndrome
- Coarctation
- Bicuspid AV
- Pregnancy
10
Q
Aortic Dissections: Predisposing conditions?
Hx HTN?
A
~90% of patients
11
Q
Aortic Dissections: Predisposing conditions?
Advanced age?
A
> 60 yo
12
Q
Aortic Dissections: Predisposing conditions?
congenital Heart diseases?
A
Coarctation of aorta, bicuspid aorta
13
Q
Aortic Dissections: Predisposing conditions?
Pregnancy?
A
Uncommon
14
Q
AORTIC DISSECTIONS
Causes (Inciting Events) – 3 main
A
Increased Physical Activity Emotional Stress Blunt Trauma Can also occur without any physical activity Ie: Cannulation for bypass
15
Q
Aortic Dissections: Mechanism
A
Intimal Tear
Presence of a weakened aortic wall
Areas experiencing greatest mechanical shear forces (Points where the aorta is fixed like ductus arteriosa, there is increased shear stress applied to the aortic wall)
16
Q
Ascending Aortic Dissection %?
A
61%
17
Q
Descending Aortic Dissection %?
A
24%
18
Q
Isthmus (Distal to Left Subclavian) Aortic Dissection %?
A
16%
19
Q
Arch Aortic Dissection %?
A
9%
20
Q
Abdominal Aortic Dissection %?
A
3%
21
Q
Propagation of an aortic dissection can occurs how quick? and is driven by what?
A
Occurs within seconds
Driven by pulse pressure and ejection velocity
22
Q
Propagation of an aortic dissection what other arteries can be involve?
A
Origin of arteries (including coronary arteries) may be involved in Aortic Dissections
—-Vessel occlusions can also occur (Due to compression by the false lumen)
23
Q
DeBakey Classification
A
3 types based upon location of intimal tear and which section of the aorta is involved
TYPE I, II, III A III B
24
Q
Type II DeBakey
Intimal Tear: ?
Dissection:?
A
Intimal Tear: Asceding Aorta
Dissection: Ascedng Aorta only
Stops before innominate artery
25
Type I DeBakey
Intimal Tear: ?
Dissection:?
Intimal Tear: Asceding Aorta
| Dissection: All parts of thoracic aorta (ascending, arch, and descending)
26
Type IIIA DeBakey
Intimal Tear: ?
Dissection:?
Intimal Tear: Descending Aorta
| Dissection: Descending Thoracic only distal to left subclavian, ends above diaphragm
27
Type IIIB DeBakey
Intimal Tear: ?
Dissection:?
Intimal Tear: Descending Aorta
| Dissection: Below diaphragm
28
STANFORD (DAILY) CLASSIFICATION
Type A
where? usually what kind of cases?
```
Ascending Aorta
Any involvement regardless of where tear is
Regardless of how far it propagates
Usually emergent/ urgent cases
More virulent course
```
29
STANFORD (DAILY) CLASSIFICATION
| Type B where?
Distal aorta
| Any part of aorta distal to left subclavian
30
Prognosis for untreated ascending dissection
DISMAL
2 day mortality
50%
31
Prognosis for untreated ascending dissection
DISMAL
3 month mortality
90%
32
Usual cause of death of an Aortic dissection?
Rupture of the false lumen into the pleural space or pericardium
33
Lower incidence of death with what type of aortic dissection?
Lower incidence with DeBakey Type III or Stanford B dissections
34
Other causes of death from an Aotic dissection? (4)
Progressive heart failure (AV involvement)
MI (Coronary Involvement)
Stroke (Occlusion of cerebral vessels)
Bowel Gangrene (Mesenteric artery occlusion)
35
AORTIC DISSECTIONS
Surgical Mortality %
highest and lowest types?
3-24%
Depends on affected section of aorta
Aortic Arch–Highest mortality
Descending Thoracic-lowest mortality
36
ANEURYSMS Incidence:
European Studies show 460/100,000 Thoracic
| Aneurysms
37
ANEURYSMS Incidence:
| Involved Ascending Aorta % occurrence?
45%
38
ANEURYSMS Incidence:
| Involved Descending Aorta % occurrence?
35%
39
ANEURYSMS Incidence:
| Involved arch and Thoracoabdominal % occurrence?
Both have a 10% occurrence rate
40
Fusiform Aneurysm what?
Entire circumference of the aortic wall
41
Saccular Aneurysm is what?
Involves only part of the circumference of the aortic wall
42
Fusiform or Saccular aneurysm more common?
Saccular
43
CRAWFORD CLASSIFICATION
| Used to classify what?
Thoracoabdominal Aortic Aneurysms
Used to describe the extent of the aorta requiring replacement
Extent I, II, III, IV
44
CRAWFORD Extent I :
| involves what?
Involves most or all of the descending thoracic aorta and upper abdominal aorta.
(Aneurysm)
45
ANEURYSM–CRAWFORD Extent II :
| involves what?
Involves most or all of descending thoracic aorta and extends into infrarenal abdominal aorta
46
ANEURYSM–CRAWFORD Extent III :
| involves what?
Involves the distal ½ or less of descending thoracic aorta and varying portion of abdominal aorta
47
ANEURYSM–CRAWFORD Extent IV :
| involves what?
Involves most or all abdominal aorta
48
How often to aortic aneurysms rupture
More than ½ of aortic aneurysms rupture
49
Untreated 5 year survival of a thoracoabdominal aortic aneurysm is?
13-39%
50
Other complications of aneurysms are? (3)
Mycotic infection
Atheroembolisation
Dissection (rare)
51
Predictors of poor prognosis for aneurysms? 3
Larger size (less than 10cm max transverse
diameter)
Presence of other symptoms
Associated CV Disease (CAD, MI, CVA)
52
THORACIC ARTERY TEARS -
| Majority occurs when?
after a trauma
Involve deceleration injury (MVA)
--Large shear stress on points of aortic wall that are relatively immobile.
Leads to immediate exsanguination and death
53
After a thoracic artery tear caused by a trauma -- what % make it to the hospital?
10-15% are lucky
Maintain the integrity of the adventitial covering of the aortic lumen
Survive to emergency care
54
thoracic artery tear most occur where?
distal to the origin of the left subclavian artery
| Due to fixation at the point of the ligamentum arteriosum
55
thoracic artery tear 2nd most common site
Ascending aorta just distal to the Aortic Valve
56
Aneurysms Diagnosis?
Asymptomatic until late in course
Medical evaluation for unrelated problem or
complication of aneurysm
57
Thoracic artery Trauma Rupture Diagnosis?
If they survive trauma
| Signs/symptoms similar to descending aortic aneurysm
58
Aneurysms Diagnosis?
Asymptomatic until late in course
Medical evaluation for unrelated problem or
complication of aneurysm
59
Dissections Diagnosis ?
Dramatic onset
60
Dissection in Ascending Aorta Indication for surgery?
Acute Type A
Virulent Course
High Mortality
61
Ascending Aorta Aneurysm indication for surgery? (5)
```
Persistent pain despite small aneurysm
AV Involvement creating MI
Angina
Rapidly expanding
Greater than 5-5.5 cm diameter (prob should be closer to 4.5 cm though)
```
62
Ascending Aotrta Aneurysm indication for surgery size?
Greater than 5-5.5 cm diameter (prob should be closer to 4.5 cm though)
63
Dissections in Aortic Arch Indication for surgery?
Acute, limited to arch (rare)
64
Aneurysm in Aortic Arch Indication for surgery? (5)
| size?
Repair of arch aneurysm is more complicated
Carries increased morbidity and mortality
Persistent symptoms
Greater than 5.5-6cm
Progressive expansion
65
Dissection Descending Aorta Indication for surgery? (6)
```
Medical management in acute phase
Failure to control hypertension medically
Continued pain
Enlargement on CXR, CT, Angio
Neurologic deficit
Renal/ GI Ischemia
```
66
Aneurysm Descending Aorta Indication for surgery? (4)
| size?
Greater than 5-6cm
Expanding
Leaking
Chronic, causing persistent pain
67
CPB w/out circ arrest in very proximal aneurysms limited to what two areas?
(DESCENDING AORTA)
the Aortic Root or Ascending Aorta
68
CPB w/out circ arrest - Cannulate where??
Dual stage canulate?
or Bicaval
(DESCENDING AORTA)
- ascending aorta or transverse aorta
| - in RA
69
CPB w/out circ arrest -- where do you cross clamp?
LV/PA Vent and CPG??
(DESCENDING AORTA)
- -Cross clamp proximal to the Innominate Artery
| - - normal
70
CPB w/out circ arrest
If patient is unstable prior to sternotomy–cannulate where??
(DESCENDING AORTA)
femoral to go on CPB prior to sternotomy
71
DHA and brain ischemia
1. Rates of TIA, Stroke, Early Mortality?
2. Perioperative neurologic complications?
3. Mortality?
(study by Svensson et al. looked at protective limits of DHCA)
1. Low
2. Higher when DHCA was greater than 40min
3. Increased dramatically when DHCA was greater than 65 min
72
Retrograde Cerebral Perfusion - benefits? (5)
- 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
73
HOW TO DO A CIRC ARREST CASE
| Need to monitor what 2 things?
```
TEMPERATURES
- Nasopharyngeal / Bladder
- Arterial
- Venous
- Water
BRAIN
- EEG–Brain activity
- Electrocerebral silence dictates adequate cerebral cooling
```
74
HOW TO DO A CIRC ARREST CASE
| Drugs?
Mannitol (25g) and Steroids
Enhances cerebral protection
Put in the pump prior to turning off the pump (Prime?)
75
HOW TO DO A CIRC ARREST CASE
Cannulation
- Arterial and Venous
Axillary Cannulation is preferred
-Artery is usually exposed prior to sternotomy
After heparin is given, 8mm graft is sewn to the artery, and cannula placed in it.
- In an emergency–femoral artery is used
If it’s a dissection, make sure that the cannula is in the true lumen!
Venous cannula
–RA, Bicaval, Femoral
Depends on need and access
76
HOW TO DO A CIRC ARREST CASE
| Pump flows can be reduced to what CI?
Pump flows can be reduced to a CI of 1.6-1.8 L/min/m2
77
A 10°C decrease in tempearture causes what effect on blood viscosity?
20-25% increase in
78
HOW TO DO A CIRC ARREST CASE
| Hct of what? why??
Hemodilution to a hct of less than 25%
- saw hypothermia-induced hyperviscosity
- Hct kept low until rewarm, and than Hemoconcentrate
Hemodilution - Reduces O2 carrying capacity, but overall O2 delivery improves
(Decreased viscosity enhances the flow in the microcirculation)
79
HOW TO DO A CIRC ARREST CASE
| At fibrillation what do you do?? how is arrest maintained?
-Give CPG via retrograde cannula
Remember aneurysm/dissection is probably in the ascending aorta or arch, therefore no antegrade CPG.
-If the AV is competent and a AoXC can be safely put on the aorta w/o damaging tissue
Give antegrade CPG
-Arrest is maintained with deep hypothermia
80
HOW TO DO A CIRC ARREST CASE
when watching the EEG when do you cool till? and how long does it take?
Temps?
```
Keep cooling until EEG shows no cerebral
electrical activity
Usually takes about 20-25 min.
Brain Temp 18-20°C
Cool no lower than 15 °C
```
81
HOW TO DO A CIRC ARREST CASE
| When not using an EEG cool how long? temp?
Cool for at least 25 min to a target core temp of 18-20°C
82
HOW TO DO A CIRC ARREST CASE
| At EEG silence give what?
Give pentobarbital
Circulate for 3 minutes
Head is packed in ice to facilitate surface cooling
Put patient in Trendelenburg position
83
```
HOW TO DO A CIRC ARREST CASE
Flow is turned off
Patient is drained
Innominate artery is snared
Initiate what?????
Right axillary–innominate artery–snare diverts blood antegrade through right common carotid–brain.
What is Opened???
```
Initiate ACP–10mL/kg/min
Aorta is opened
84
HOW TO DO A CIRC ARREST CASE
| when the Aorta is opened (after flow has been turned off) what happens?
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
85
```
HOW TO DO A CIRC ARREST CASE
Proximal graft attached
Slowly rewarm to what????
Proximal complete
THEN DO WHAT?
AoXC removed
TEE is utilized to make sure there is no air
present
CPB is terminated
```
36.5°C
Not to exceed a 10°C gradient between arterial blood and nasopharyngeal / bladder
Deair with venting needle through graft
86
HOW TO DO A CIRC ARREST CASE
End of graft is sewn to proximal descending
thoracic aorta, transverse arch or distal
ascending aorta
Attach head vessels (by Island or Branched graft)
Put patient in steep Trendelenburg
Cardiotomy suction placed where????
Release tourniquet on innominate
Slowly increase flow WHAT???
If cannulated femorally, move the cannula to the arch
Systemic circulation re-estabilished
in unattached graft
to full flow (50mL/kg/min) as the aorta and graft are deaired
87
```
OFF PUMP
Want systolic BP appx ???
Mean ???
HR ???
CI ???
```
Want systolic BP appx 100-120mmHg
Mean 70-90mmHg
HR 60-80 BPM
CI 2.0-2.5 L/min/m2
88
COMPLICATIONS OF AORTIC SURGERY AND DHCA (8)
```
Air Emboli
Clots
LV Dysfunction
MI (Reimplanting coronaries)
Renal Failure
Respiratory failure
Coagulopathy
Hemorrhage
```
89
TEVAR stands for?
Thoracic Endo Vascular Aortic Repair
90
TEVAR - some facts??
```
Requires femoral access
Flouroscopy
Graft self-deploys
Req’s flouroscopy to check position
Requires systemic heparinization
```
91
TEVAR requires what??
Requires proximal “Landing Zone” of 15mm
| length
92
TEVAR - distal end needs to be?
Distal end needs to be non-aneurysmal
93
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
```
94
TEVAR - considerations? (3)
Aortic Tortuosity, calcification, atherosclerosis
95
TEVAR - complications? (6)
```
-Conversion to open procedure
(Aortic Rupture / dissection
Malposition–causing visceral ischemia)
-Bleeding
-Endoleak
(Blood flows back into the aneurysmal sac after the endovascular graft is placed
Usually observe and hope it spontaneously resolves)
-Stroke
-Paraplegia
-Contrast Nephropathy
```
96
Left Heart Bypass - ECC circuit?
```
Tubing
Centrifugal pump
No Reservior
No H/E
No Bubble Trap
Excluding those help minimize the heparinization required
```
97
Left Heart Bypass -
is basically a what?
used on what?
what do heart and lungs do?
```
Basically, a shunt around the aneurysm/
dissection
Used on Descending legions
Heart pumps blood to the lungs
Lungs oxygenate
```
98
Left Heart Bypass -
| Venous and Arterial Cannulation?
--Venous cannula places in LA/ L. Pulmonary veins
Risk of air embolism
Move tip of cannula–impair drainage
--Could cannulate Apex of LV
Great flow
Risk of LV injury
---Arterial cannula placed in descending aorta
99
LEFT HEART BYPASS
| If the patient needs volume?
Anesthesia must give
100
LEFT HEART BYPASS
| Arterial pressure monitored where?
Monitored at radial or brachial artery (upper body)
| Monitored at femoral artery (lower body)
101
Marfan's Syndrome does what to the vessels??
Arteries are weakened, particularly the aorta
Aorta dilates–weakens
Under exertion the aorta can tear–dissection
Also have MV prolapse and AI
