Aortic Arch Flashcards
Most common location and agents causing mycotic aneusrysms of Arch
- Lesser curvature of aortic arch or
- Opposite the visceral vessels in the abdomen.
typical organisms are
a. E.Coli, b. Salmonella c. Streptocci
“called myocotic because of grey, slimmy color”
List common vasculitis and aortitis
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
List brain protective features for all patients
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
What is brain protection specific for retrograde perfusion
Superior vena cava cannula inserted
Snared below azygous vein
Flow rate at 300 to 500 ml/min
Pressure < 25-35mmHg to avoid cerebral edema
What is genetics behind Marfan
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
Describe genetics and features of Loeys-Dietz syndrome
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
What are features and Genetics of Ehlers-Danlos
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
What is benefit of selective antegrade cerebral perfusion and Mild (28-30degrees) systemic hypothermic circulatory arrest for aortic replacement
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.
Describe Crawford classification of TA
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
Where is the artery of Adamkiewicz
T8 to T12
List techniques to provide spinal protection to thoracic aortic surgery
Circulatory arrest Selective cooling of epidural or subarachnoid space Reimplantation of intercostals CSF drainage Perfusion of distal aorta -Left heart bypass - Gott Shunt
List surgical strategies for all type of descending thoracic aneurysms
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
What additional stragetgies can be performed when dealing with Crawford type I or II
CSF drainage
Left heart bypass during proximal anastomosis
selective perfusion of celiac axis and superior mesenteric artery during intercostals and visceral anastomosis
How do you accomplish CSF drainage
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
Describe benefit and set up for left heart bypass
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
List benefits of endovascular therapy for the treatment of thoracic aortic disease
No Cross clamping Peripheral access avoiding thoracotomy Minimal Respiratory complications Shortening hospital stay and recovery time No Heparinization Less morbidity associated with procedure
What anatomical requirements are needed for endovascular repair
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
What are types of endoleaks
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?
Endo vs open repair of TA
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
What is benefit of axillary artery cannulation in Arch Aneurysms
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
What is evidence and dose of steroids for aneurysms of the arch
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
What are specific details of axillary cannulation flow for cerebral perfusion
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
List benefits of alpha stat during CPB
Preserves cerebral autoregulation
Maintains metabolic suppression
Reducing the risk of cerebral embolization
How do you ensure correct cooling of the head
Long duration of cooling
Low esophageal temp
High jugular venous oxygen saturation
topical hypothermia (ice packs on the head)
What is the perfusate temperature when rewarming
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
How do Somatosensory-evoked potential (SSEPs) and motor-evoked potential
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.
What is the pathophysiology of medial degenerative disease
loss of elastic fibers
medial necrosis as a loss of smooth muscle cells.
occur in older adults, smoke history, history of HTN, and COPD
