Previous exam 2001 Flashcards
Indications for surgery for type B dissection
pain malperfusion limb ischemia visceral ischemia uncontrolled hypertension contained rupture of dissected segment increase in size by >1cm in 6 months Aneurysm size > 6.5cm
Factors affecting paraplegia during thoracic aneurysm repair
factors affecting cross clamp time perioperative hypotension location of aneurysm Crawford I (13% incidence) left subclavian to abdominal aorta (not involving renals) Crawford II (30%) Left subclavian to abdominal aorta (involving infra renals) Crawford III (7%) distal half of the descending aorta and substantial segments of abdo aorta Crawford IV 4% upper abdo aorta +/- infra renal aorta (not much descending aorta increased age replacement below T4 absence of distal perfusion emergency surgery
Measures to prevent paraplegia in TA repair
distal perfusion-left heart bypass (maintain SBP > 90) moderate hypothermia (30degree) re-implantation of intercostals CSF drainage (CSF < 10mmHg) epidural cooling steriods, barbiturates, mannitol avoid hyperglycemia avoid nipride-not only causes periop hypotension but also causes cerebral vasodilation and increased CSF
What is anatomy of spinal cord
Anterior longitudinal spinal artery is formed by joining branches from right and left vertebral arteries runs down the entire length of spinal cord supplies blood to the cervical spinal cord in the thoracic and lumbar spine this artery is fed by collaterals (anterior radicular arteries Paired posterior longitudinal spinal arteries arise from R and L vertebrals Segmental spinal arteries supply thoracic and lumbar cord originate from intercostal and lumbar arteries that join to form: Ant Radicular arteries–supply anterior longitudinal spinal artery Artery of Admkiewicz–largest radicular artery (T9-to L2)
Describe what happens to pH when cooling
Hypothermia decreases the tendency of weak acids and bases to dissociate Buffering capacity of blood remains constanthydroxide ions (OH-) and hydrogen ions (H+) [OH/H+] at 16:1 pH rises with hypothermia (become alkaline) ph increases 0.0134 for each degree C of hypothermia pco2 decreases 4.5% for each degree of hypothermia hypothermia leads
What are advantages to pH and alpha stat
Alpha stat===No further CO2 is added. Total CO2 content is constant and no adjustments are made for temp (ratio of OH/H is constant) hydroxide ions (OH-) and hydrogen ions (H+) Benefit of alpha stat allows for preservation of cerebral autoregulation as metabolism and cerebral blood flow are coupled improved myocardial contractility and metabolism increased defibrillation thresholds increased subendocardial blood flow decreased cerebral blood flow pH–exogenous CO2 is added to maintain pH at 7.40. Results in acidosis when corrected for temp. CO2 increases cerebrovasodilation and therefore increases cerebral blood flow and potential advantage of improved cooling but at higher risk of emboli and cerebreal edema.
List complications of vavular substitues
infection paravalvular leak patient prosthesis mismatch hemolysis structural valve deterioration thrombosis anticoagulation
List mechanism and side effect of OKT3, cyclosporing, azathioprine, and prenisone
OKT3: monoclonial murine antibody of T cells (Anti CD3 antibody) side effect: infection:pulmonary edema/reactive airways/bronchoconstriction Cyclosporin: inhibitor of Calcium calcineurin phosphatase, thus inhibiting gene activationof IL-2 production. More selective immunosuppresion than steroids side effect: nephrotxicity, heptotoxicity, neurotoxicity, hypertension, Gingival hyperplasia Azathioprine: inhibitis purine synthesis through all bone marrow lineages–inhibits antigen stimulated proliferation of lymphocytes side effect: bone marrow suppression (anemia/leukopenia/thrombocytopenia/pancreatitis/hepatitis/alopecia Prednisone: blocks all lines of immune response: inhibits IL1; IL3; IL 6; ICAM-which would normally increase the signal for lympohyte activation. side effect: pyschosis;HTN;poor wound;Glucose intolerance;osteoporsis;impotence
Side effects of amiodarone
corneal deposits, halos and blurred vision acute hypersensitivity pneumonitis hyper/hypotheyroid QT prologation AV block Hepatitis photosensivity
Indications for chronic MR surgery
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What is mechanism for pulmonary hypertension after protamine and how do you treat
Heparin-protamine complex stimulate thromboxane A2 from pulmonary macrophages treatment stop protamine 100 fio2 stop anesthetics give heparin on CPB reasonable to give steroids because unable to know if it’s type II or III If re-operation needed then Heparinase lactoferrin Methylene blue
Classification of interrupted aortic arch
Type A (40%) Interrupted distal to the left subclavian Type B (55%) Interrupted left carotid and the left subclavian Type C (5%) Interrupted between the inominate and the left carotid Most have a large VSD and varying degree of other left sided obstruction and hypoplasia. 40 to 50% have bicuspid aortic valve
5 year old girl with Turners syndrome presents with leg pain and chest pains
Higher incidence of coarctation in females with Turners. They present with with proximal hypertension (headaches, epitaxis, rupture cerebral aneurysm) or claudication surgical options resection, end to end anastomosis prosthetic patch aortoplasty prosthetic interposition graft subclavian flap aortoplasty resection with extended end to end anastomosis
What are risks for AV groove disruption
overzealous removal of calcium from posterior annulus of mitral valve implanting too large a prosthesis in MV position lifting the heart for de-airing after valve implantation
7 year old infant presents to ER with resp distress, severe metabolic acidosis, absent femoral pulses
Watch for acyanotic ductal dependent lesions with left side obstructions coarctation hyoplastic arch interrupted arch MS AS HLHS
