Flashcards in The Surgical Review- Vascular Deck (83)
three layers of blood vessel walls and tissue composition
1. Tunica intima: endothelial cells
2. Tunica media: smooth muscle cells
3. Tunica Adventitia: adipose and supportive connective tissue (in large vessels this contains the vasa vasorum which is the blood supply of the vessel wall)
what are 2 ways HTN causes atherosclerosis
1. Direct endothelial damage
2. HTN -> elevated levels of angiotensin II (potent vasoconstrictor) that produces superoxide anions and pro inflammatory cytokines from smooth muscle cells leading to endothelial injury
why do diabetic patients have impaired vasodilation?
1. Dysfunction of endothelial nitric oxide synthase
2. increased production of endothelia-1, a potent vasoconstrictor
what are the key components of the atherosclerotic plaques?
1. necrotic core containing foam cells and extracellular lipids
2. fibrous cap of smooth muscle cells, lymphocytes and connective tissue
the two most common structural sources of emboli?
1. Internal carotid
what is the gold standard for diagnosing carotid stenosis?
contrast angiography but this is reserved for complex or equivocal cases, screen with CDUS (carotid duplex US) and confirm with MRA
which nerve is most often traumatized during CEA?
What are the six P's of acute ischemia?
1. Pain** most common
initial management of acute limb ischemia?
start SQH and take to arteriography
what can cause neurogenic claudication?
1. Spinal stenosis
2. Nerve compression
3. Diabetic Neuropathy
what does ischemic rest pain indicate?
that the blood supply is insufficient to meet the metabolic demands of the resting tissue, thus pain is aggravated by elevation of the extremity
what tests an be used to establish diagnosis of arterial occlusive disease? (3)
1. Segmental systolic blood pressure
2. The ABI
3. Pulse volume recordings (PVRs)
How do you test segmental systolic blood pressures?
1. Doppler segmental pressures of brachial aa to the proximal femoral aa: should have change >20mmHg
2. Measure proximal and distal thighs, and proximal and distal calves: a pressure drop of >30mmHg signifies a significant obstruction
What are the ranges of ABI for normal, claudication and critical ischemia?
Normal: ABI >1.0
Claudication: ABI 0.5-0.84
Critical Ischemia: ABI
what are the three common time points for bypass graft failure and what are the usual causes?
1. Early (2yrs): natural progression of atherosclerotic disease
atherosclerotic disease is the major cause of aneurysmal disease in all areas except what?
ascending aorta 2/2 cystic medial necrosis
screening and diagnostic tests of choice for AAA?
screening: abd US
when do you operate on a AAA?
prior to aortic cross clamping in AAA repair, what two anatomic considerations must be made?
1. identify the left renal vein and protected to avoid injury
2. if the IMA is sacrificed, in regards to pelvic outflow, at least one hypogastric (internal iliac aa) must have good flow to prevent colon ischemia and vasculogenic impotence
which visceral arteries are known to have aneurysms? how do you repair?
1. Hepatic- repair
2. Renal- repair
3. Splenic- can monitor with exceptions
*repair is with exclusion and bypass grafting
When should one repair a splenic aneurysm?
1. In pregnant women or those about to become pregnant
2. Those larger than 2cm
when should iliac artery aneurysms be repaired? how to repair?
2. Larger than 3cm
*repair with stent or bypass graft and exclusion
when should femoral artery aneurysms be repaired? how to repair?
2. Larger than 2.5cm
* repair with bypass and exclusion
when should popliteal aa aneurysms be repaired?
2. Larger than 2 cm
* repair with exclusion and bypass grafting or stent
Renal artery stenosis is mostly caused by what two pathologies?
1. Atherosclerotic disease: more common on left side, older tips
2. Fibromuscular dysplasia: younger women, bilateral or right sided disease
whats the most commonly performed confirmatory test for renal artery stenosis?
renal vein renin assay: measures renin activity in the renal vein and compares it to systemic renin activity in the case of bilateral renal artery stenosis
what is the most commonly affected upper extremity vessel in upper extremity arterial occlusive disease?
explain subclavian steal syndrome
- occurs with proximal stenosis or occlusion of the subclavian artery
- the delivery of blood to the extremity thus depends on reversed flow through the ipsilateral vertebral artery via the circle of willis
- strenuous activity of the affected UE results in stealing blood from the circle of willis and results in vertebrobasilar insufficiency = syncope/neurologic symptoms
what are the components of the scalene triangle?
1. Anterior scalene
2. Middle scalene
3. First rib
- the subclavian aa and brachial plexus pass through this
- in thoracic outlet syndrome, anomalous cervical rib or hypertrophy of the anterior scalene muscle can cause compression on the plexus, artery or vein