Vascular Surgery Flashcards
What is atherosclerosis?
Diffuse disease process in arteries.
Atheromas containing cholesterol and lipid form within the intima and inner media, often accompanied by ulcerations and smooth muscle hypertrophy.
What is the common theory of how atherosclerosis is initiated?
- Endothelial injury
- Platelets adhere
- Growth factors released
- Smooth muscle hyperplasia and plaque deposition
What are the risk factors for atherosclerosis?
HTN, smoking, diabetes, family history, hypercholesterolemia, high LDL, obesity, sedentary lifestyle
What are the common sites of plaque formation in arteries?
Branch points (e.g. carotid bifurcation), tethered sites (e.g. superficial femoral artery in Hunter’s canal in the leg)
What must be present for a successful arterial bypass operation?
- Inflow (e.g. patent aorta)
- Outflow (e.g. open distal popliteal artery)
- Run off (e.g. patent trifurcation vessels down to the foot)
What is the major principle of safe vascular surgery?
Get proximal and distal control of the vessel to be worked on
What does it mean to Potts a vessel?
Place a vessel loop twice around a vessel so that if you put tension on the vessel loop it will occlude the vessel
What is the suture needle orientation through graft vs. diseased artery in a graft to artery anastomosis?
Needle “in-to-out” of the lumen in diseased artery to help tack down the plaque and the needle “out-to-in” on the graft
What are the 3 layers of an artery?
- Intima
- Media
- Adventitia
Which arteries supply the blood vessel itself?
Vaso vasorum
What is a true aneurysm?
Dilation (> 2 nL diameter) of all 3 layers of a vessel
What is a false aneurysm?
Dilation of artery not involving all 3 layers (e.g. hematoma with fibrous covering).
Often connects with vessel lumen and blood swirls inside the false aneurysm.
What is endovascular repair?
Placement of a catheter in artery and then deployment of a graft intraluminally
How can you remember the orientation of the lower exterior arteries below the knee on A-gram?
LAMP:
Lateral Anterior tibial
Medial Posterior tibial
What is PVD?
Peripheral Vascular Disease
Occlusive atherosclerotic disease in the lower extremities.
What is the most common site of arterial atherosclerotic occlusion in the lower extremities?
Occlusion of SFA in Hunter’s canal
What are the symptoms of PVD?
Intermittant claudications, rest pain, erectile dysfunction, sensorimotor impairment, tissue loss
What is intermittent claudication?
Pain, cramping, or both of the lower extremity, usually the calf muscle, after walking a specific distance.
Then the pain/cramping resolves after stopping for a specific amount of time while standing.
Pattern is reproducible.
What is rest pain?
Pain in the foot, usually over the distal metatarsals.
This pain arises at rest (classically at night, awakening the patient)
How can vascular causes of claudication be differentiated from nonvascular causes (such as neurogenic claudication or arthritis)?
History (in the vast majority of patients); noninvasive tests
What is the differential diagnosis of lower extremity claudication?
Neurogenic (e.g. nerve entrapment, discs), arthritis, coarctation of aorta, popliteal artery syndrome, chronic compartment syndrome, neuromas, anemia, diabetic neuropathy pain
What are the signs of PVD?
Absent pulses, bruits, muscular atrophy, decreased hair growth, thick toenails, tissue necrosis/ulcers/infection
What is the site of a PVD ulcer vs. a venous stasis ulcer?
PVD arterial insufficiency ulcer: usually on the toes/feet
Venous stasis ulcer: medial malleolus
What is the ABI?
Ankle to Brachial Index:
Ratio of the systolic blood pressure at the ankle to the systolic blood pressure at the arm.
Pressure taken with Doppler.
What ABIs are associated with normals, claudicators, and rest pain?
Normal ABI: > 1.0
Claudicators ABI: < 0.6
Rest pain ABI: < 0.4
Who gets false ABI readings?
Patients with calcified arteries, especially those with diabetes
What are PVRs?
Pulse Volume Recordings:
Pulse wave forms are recorded from lower extremities representing volume of blood per heart beat at sequential sites down leg.
Large wave form means good collateral blood flow.
Prior to surgery for chronic PVD, what diagnostic test will every patient receive?
A-gram maps disease and allows for best treatment option (i.e. angioplasty vs. surgical bypass vs. endarterectomy)
What is the bedside management of a patient with PVD?
- Sheep skin (easy on the heels)
- Foot cradle (keeps sheets/blankets off the feet)
- Skin lotion to avoid further cracks in the skin that can go on to form a fissure and then an ulcer
What are the indications for surgical treatment of PVD?
STIR: Severe claudication refractory to conservative treatment that affects quality of life Tissue necrosis Infection Rest pain
What is the treatment of claudication?
Conservative treatment (e.g. exercise, smoking cessation, treatment of HTN, diet, aspirin +/- pentoxifylline (Trental)
How can the medical conservative treatment for claudication be remembered?
PACE: Pentoxifylline Aspirin Cessation of smoking Exercise
How does aspirin work?
Inhibits platelets (inhibits cyclooxygenase and platelet aggregation)
How does pentoxifylline (Trental) work?
Results in increased RBC deformity and flexibility
What is the risk of limb loss with claudication?
5% at 5 years
10% at 10 years
What is the risk of limb loss with rest pain?
> 50% of patients will have amputation at some point
In the patient with PVD, what is the main postoperative concern?
Cardiac status, because most patients with PVD have CAD (20% have an AAA).
MI is the most common cause of postoperative death after a PVD operation.
What is Leriche’s syndrome?
Buttock claudication, impotence, and leg muscle atrophy from occlusive disease of the iliac arteries and distal aorta
What are the treatment options for severe PVD?
- Surgical graft bypass
- Angioplasty (balloon dilation)
- Endarterectomy (remove disease intima and media)
- Surgical patch angioplasty (place patch over stenosis)
What is a FEM-POP bypass?
Bypass SFA occlusion with a graft from the FEMoral artery to POPliteal artery
What is a FEM-DISTAL bypass?
Bypass from the FEMoral artery to a DISTAL artery (e.g. peroneal, anterior tibial, or posterior tibial artery)
What graft material has the longest latency rate?
Autologous vein graft
What is an in situ vein graft?
Saphenous vein is more or less left in place, all branches are ligated, and the vein valves are broken with a small hook or cut out.
A vein can also be used if reversed so that the valves do not cause a problem.
What type of graft is used for above-the-knee FEM-POP bypass?
Either vein or Gortex graft.
Vein still has better patency.
What type of graft is used for below-the-knee FEM-POP or FEM-DISTAL bypass?
Must use vein graft.
Prosthetic grafts have a prohibitive thrombosis rate.
What is dry gangrene?
Dry necrosis of tissue without signs of infection
What is wet gangrene?
Moist necrotic tissue with signs of infection
What is blue toe syndrome?
Intermittent painful blue toes (or fingers) due to microemboli from a proximal arterial plaque
What are the indications for lower extremity amputation?
Irreversible tissue ischemia and necrotic tissue; severe infection; severe pain with no bypassable vessels; patient not interested in bypass procedure
What are 6 types of lower extremity amputations?
- AKA (above-the-knee)
- BKA (below-the-knee)
- Symes
- Transmetatarsal
- Toe
- Ray (removal of toe and head of metatarsal)
What is acute arterial occlusion?
Acute occlusion of an artery, usually by embolization (also, acute thrombosis of atheromatous lesion, vascular trauma)
What are the classic signs and symptoms of acute arterial occlusion?
Six P’s:
Pain, Paralysis, Pallor, Paresthesia, Polar, Pulselessness
What is the classic timing of pain with acute arterial occlusion from an embolus?
Acute onset; patient can classically tell you exactly when and where it happened
What is the immediate preoperative management of acute arterial occlusion?
- Anticoagulate with IV heparin (bolus followed by constant infusion)
- A-gram
What are the sources of emboli with acute arterial occlusion?
- Heart (85%: clot from AFib, clot forming on dead muscle after MI, endocarditis, myxoma)
- Aneurysms
- Atheromatous plaque
What is the most common cause of embolus from the heart?
AFib
What is the most common site of arterial occlusion by an embolus?
Common femoral artery (SFA is the most common site of arterial occlusion from atherosclerosis)
What diagnostic studies are in order for acute arterial occlusion?
- A-gram
- ECG (looking for MI, AFib)
- Echocardiogram (looking for clot, MI, valve vegetation)
What is the treatment for acute arterial occlusion?
Surgical embolectomy via cutdown and Fogarty balloon (bypass is reserved for embolectomy failure)
What is a Fogarty?
Fogarty balloon catheter: catheter with a balloon tip that can be inflated with saline, used for embolectomy
How is a Fogarty catheter used?
Insinuate the catheter with the balloon deflated past the embolus and then inflate the balloon and pull the catheter out.
How many mm in diameter is a 12 French Fogarty catheter?
Divide French number by pi.
So 12 French is about 4 mm in diameter.
What must be looked for postoperatively after repercussion of a limb?
Compartment syndrome, hyperkalemia, renal failure from myoglobinuria, MI
What is compartment syndrome?
Leg (calf) is separated into compartments by very unyielding fascia.
Tissue swelling from reperfusion can increase the intracompartmental pressure, resulting in decreased capillary flow, ischemia, and myonecrosis.
Myonecrosis may occur after the intracompartmental pressure reaches only 30 mmHg.
What are the signs and symptoms of compartment syndrome?
Pain (especially after passive flexion/extension of the foot), paralysis, paresthesias, pallor.
Pulses are present in most cases because systolic pressure is much higher than the minimal 30 mmHg needed for the syndrome.
Can a patient have a pulse and compartment syndrome?
Yes
How is the diagnosis of compartment syndrome made?
History, compartment pressure measurement
What is the treatment of compartment syndrome?
Treatment includes opening compartments via bilateral calf-incision fasciotomies of all 4 compartments in the calf
What is a AAA?
Abdominal aortic aneurysm
Abnormal dilation of the abdominal aorta (> 1.5-2 times normal), forming a true aneurysm
What is the M:F ratio for AAA?
6:1
By far, which group is at highest risk for AAA?
White males
What is the common etiology for AAA?
Believed to be atherosclerotic in 95% of cases (inflammatory otherwise)
What is the most common site of AAA?
Infrarenal (95%)
What is the incidence of AAA?
5% of all adults older than 60 years
What percentage of patients with AAA have a peripheral arterial aneurysm?
20%
What are the risk factors for AAA?
Atherosclerosis, HTN, smoking, male, advanced age, connective-tissue disease
What are the symptoms of AAA?
Most AAAs are asymptomatic and discovered during routine abdominal exam by PCPs.
Vague epigastric discomfort to back and abdominal pain.
What do testicular pain and AAA signify?
Retroperitoneal rupture with ureteral stretch and referred pain to the testicle
What are the risk factors for AAA rupture?
Increasing aneurysm diameter, COPD, HTN, recent rapid expansion, large diameter, symptomatic
What are the signs of AAA rupture?
- Abdominal pain
- Pulsatile abdominal mass
- Hypotension
By how much each year do AAAs grow?
3 mm/year on average
Why do larger AAAs rupture more often and grow faster than small AAAs?
Laplace’s Law (wall tension = pressure X diameter)
What is the risk of rupture per year based on AAA diameter size?
< 5 cm: 4%
5-7 cm: 7%
> 7 cm: 20%
Where does the aorta bifurcate?
At the level of the umbilicus (thus when palpating for an AAA, palpate above the umbilicus and below the xiphoid process)
What is the differential diagnosis for AAA?
Acute pancreatitis, aortic dissection, mesenteric ischemia, MI, perforated ulcer, diverticulosis, renal colic
What are the diagnostic tests for AAA?
U/S (follow AAA clinically); CT or A-gram (assess lumen patency and iliac/renal involvement)