Aortic Arch

Question 0

Most common location and agents causing mycotic aneusrysms of Arch

Answer 0

1. Lesser curvature of aortic arch or
2. Opposite the visceral vessels in the abdomen.

typical organisms are

a. E.Coli, 
b. Salmonella
c. Streptocci

“called myocotic because of grey, slimmy color”

Question 1

What is the pathophysiology of medial degenerative disease

Answer 1

loss of elastic fibers
medial necrosis as a loss of smooth muscle cells.
occur in older adults, smoke history, history of HTN, and COPD

Question 2

List common vasculitis and aortitis

Answer 2

previous chest radiation for Hodgkins dsiease or breast malignancies  (radiation induced vasculitis is associated with severe calcification and porcelain aorta) 
Takayasu
Giant cell arteritis (Hortons disease) 
Polymyalgia rheumatic
Behcet's 
Kawasaki
Buerger's 
Logains
Ankylosing spondylitis 
Reiters
Rheumatoid arthritis

Question 3

List brain protective features for all patients

Answer 3

Systemic Hypothermia (Temperatures can change...) 
Head packed with ice
Mannitol in prime and after arrest
EEG silence
Alpha-stat pH control
Magnesium sulfate
Membrane oxygenator
Closed circuit bag venous reservoir
Routine cell saver device 
Co2 into the field

Question 4

What is brain protection specific for retrograde perfusion

Answer 4

Superior vena cava cannula inserted
Snared below azygous vein
Flow rate at 300 to 500 ml/min
Pressure < 25-35mmHg to avoid cerebral edema

Question 5

What is genetics behind Marfan

Answer 5

Autosomial dominant with variable penetrance occurs in 1 in 5000
mutations in Fibrillin 1 expression - on chromosme 15
more then 100 mutations have been identified

Question 6

Describe genetics and features of Loeys-Dietz syndrome

Answer 6

Mutations in TGF beta receptors 1 and 2

Phenotype of 
	Hypertelorism (wide spaced eyes) 
	bifid uvula (cleft palate) 
	generalized arterial tortuosity 
	widespread vascular aneurysm

surgery receommended at 4 to 4.2cm cm

Question 7

What are features and Genetics of Ehlers-Danlos

Answer 7

Heterogeneous connective tissue disorder that involve skin and joints and can cause hyperelasticity and fragility

Cardiac involvement (vascular) is an autosomial dominant inherited disorder of connective tissue resulting from mutation of COLA31 encoding type III collagen.

25% of patients less then 20 year old die
80% before the age of 40

facial features: thin, propensity to bleed, translucent skin

Question 8

What is benefit of selective antegrade cerebral perfusion and Mild (28-30degrees) systemic hypothermic circulatory arrest for aortic replacement

Answer 8

ACP and mild systemic hypothermic circulatory arrest can safely be applied to complex aortic arch surgery up to 90 minutes

Unilateral ACP offers at least equal brain and visceral organ protection as bilateral ACP and maybe advantagous in that it reduces embolism arising from surgical manipulation on arch vessels.

Question 9

Describe Crawford classification of TA

Answer 9

type I most or all of the descending thoracic aorta and upper abdominal aorta
type II most or all of the descending thoracic aorta and most or all of the abdominal aorta
type III distal or less of descending thoracic aorta and any involvement of abdominal aorta
type IV most or all of the abdominal aorta below the diaphragm

Question 10

Where is the artery of Adamkiewicz

Answer 10

T8 to T12

Question 11

List techniques to provide spinal protection to thoracic aortic surgery

Answer 11

Circulatory arrest
Selective cooling of epidural or subarachnoid space
Reimplantation of intercostals 
CSF drainage
Perfusion of distal aorta 
	-Left heart bypass
	- Gott Shunt

Question 12

List surgical strategies for all type of descending thoracic aneurysms

Answer 12

Heparinzation of 1mg/kg
Permissive mild hypothermia (32 to 34 degrees nasopharyngeal)
Reattachment of segemental arteries (especially T7 to L2)
perfusion of renal arteries with 4 degree C crystalloid
sequential aortic clamping when possible

Question 13

What additional stragetgies can be performed when dealing with Crawford type I or II

Answer 13

CSF drainage
Left heart bypass during proximal anastomosis
selective perfusion of celiac axis and superior mesenteric artery during intercostals and visceral anastomosis

Question 14

How do you accomplish CSF drainage

Answer 14

18 guage catheter into the 2nd or 3rd lumbar space
intra-op pressure kept at 8 to 10 mmHg
Early post op keep pressure at 10 to 12 mmHg
12-15 mmHg when it is confirmed they can move their legs

Question 15

Describe benefit and set up for left heart bypass

Answer 15

provides the greatest benefit and allows time for reimplantation of vessels
beneficial in pts with poor cardiac reserve because it offloads the left ventricle

Left atrium/Left inferior pulmonary vein to left femoral artery or distal descending aorta 
Bypass flows of 1500 to-2500 ml/min
Allow heart to eject
Monitor brain saturation 
Target a distal MAP of 55 to 65mmHg

Question 16

List benefits of endovascular therapy for the treatment of thoracic aortic disease

Answer 16

No Cross clamping 
Peripheral access avoiding thoracotomy 
Minimal Respiratory complications 
Shortening hospital stay and recovery time 
No Heparinization 
Less morbidity associated with procedure

Question 17

What anatomical requirements are needed for endovascular repair

Answer 17

Oversizing –10 to 15% stent size increase then regular aorta
Landing zone– at least 2 cm adequate zone proximal for adequate fixation
Femoral artery access—femoral arteries must be 8 mm
Maximal graft size is 4 mm

Question 18

What are types of endoleaks

Answer 18

type I: inadequate proximal or distal landing zone
type II: retrograde aortic perfusions from a banch vessel
type III: fractures or holes in the material or graft-graft
type IV: porosity in the endograft material–treated with reversal of anticoagulation
type V: endotension?

Question 19

Endo vs open repair of TA

Answer 19

Blood loss is decrease
Renal failure is less
Paraplegia is less
mortaility is less 
Stroke is the same 
50% shorter length of stay 
50% shorting of ICU stay 
50% faster return to normal activity 
All cause mortality at 2 years was the same between open and stent graft repair

Question 20

What is benefit of axillary artery cannulation in Arch Aneurysms

Answer 20

Artery that is rarely involved in generalized atherscloerosis or aortic dissection
Avoids dislodgement of debris associated with central cannulation
Avoids embolization of retrograde flow
Avoids risk of local dissection with central cannulation
Risk of malperfusion is lower
Facilitates selective antegrade cerebral perfusion

Question 21

What is evidence and dose of steroids for aneurysms of the arch

Answer 21

Methlyprednisolone (1g) on initiating CPB if hypothermic circulatory arrest is planned to be greater then 30 minutes.
Steroids are continued for 48 hours post opr.
Barbituarates are not used anymore

Question 22

What are specific details of axillary cannulation flow for cerebral perfusion

Answer 22

Perfusate temperature is 15 to 20 degrees
Hematocrit is 25 to 30%
FLows of 8 to 10 cc/kg/min
Mean arterial pressure (MAP) of 40 to 60 mmHg

Question 23

List benefits of alpha stat during CPB

Answer 23

Preserves cerebral autoregulation
Maintains metabolic suppression
Reducing the risk of cerebral embolization

Question 24

How do you ensure correct cooling of the head

Answer 24

Long duration of cooling
Low esophageal temp
High jugular venous oxygen saturation
topical hypothermia (ice packs on the head)

Question 25

What is the perfusate temperature when rewarming

Answer 25

Lower the perfusate temp toward 10 degree
Hypothermic reperfusion has been shown to improve neurological outcome (but there is debate)
Never raise blood temp above 37 degrees

Question 26

How do Somatosensory-evoked potential (SSEPs) and motor-evoked potential

Answer 26

Intercostals are sacrificed gradually before starting CPB.
Each intercostal is provisionally clamped and sacrificed only if the MEP or SSEP remain unchanged for 10 minutes.
MEP and SSEP is continued until the patient exits the operating room to confirm the return of stability of signals.