Vascular Ischaemia / Vessel Diseases

Upper Extremity Disease
Claudication and disability much less common partly due to less use of arm in routine ongoing excercise cf walking.
Causes include: vasospastic, intrinsic arterial disease, inflammatory disease (e.g. takayasu's), non-inflammatory medical diseases (e.g. VTE), embolism, trauma.
Evaluation
- Full history and physical evaluating for ischaemic features, signs of insufficiency, noting all pulses, Allen's test, Dopplers, BP comparisons.
- CTA better than invasive angiography, fast, safe and accessible.
- MRA has better resolution for small vessels but access and imaging time limiting; doesn't show calcification like CTA does.
Therapy
- Avoid smoking, manage other risks for atheroma
- Other treatments targeted at cause as appropriate.
- Angiography with endovascular management follows for treatable atheromatous lesions.
--> best indicated for short segment stenoses / occlusions, except poor results in vasculitis.
--> options include balloon angioplasty, embolization of pseudoaneurysms, bare metal and covered stents, thrombolysis for acute lesions.
--> thromboembolectomy when urgent severe acute ischaemia; thrombolysis preferable otherwise and especially good for small arteries of forearm.
Endovascular Technique
- Can access proximal subclavian from femoral or same arm; usually via brachial cutdown
- Balloon angioplasty for stenotic segments
- Then stent if residual stenoses of 30% or more.
- Catheter-directed thrombolysis useful for acute thrombosis; us. via femoral,
--> pulsed-spray thrombolysis using tissue plasminogen activator (tPA), 2mg over 20min; infusion if peristent thrombosis.
--> f/up angioplasty may be needed for clot lysis or residual artery stenosis.
- If severe ischaemia from acute VTE, surgical balloon embolectomy may restore perfusion more rapidly than thrombolysis
--> if was >6h occlusion, can get compartment syndrome and require fasciotomy of forearm and hand.
See vascular access

Aorto-Iliac Occlusive Disease

Classification

3 types
image
Type 1: single level disease; confined to aorta and iliac arteries
- more common in young smokers and females
- usually presents with calf claudication
Type 2: single level; similar but more extensive abdominal disease; femorals
- also get buttock claudication, impotence and diminished or absent femoral pulses.
Type 3: multi-level disease
- spectrum from claudication to rest pain and tissue loss

Clinical / Ix

Thorough hx and exam; risk factors
Have absent or diminished femoral pulses.
Features of diminished peripheral perfusion
- coolness, pallor, dependent rubor, loss of pretibial skin turgor and hair
ABI, doppler, pulse-volume recordings, exercise testing
Then delineate with duplex USS, CTA, MRA
USS - functional; doppler; define site, distance and severity of stenoses
- then CTA to clearly show anatomy
- MRA if contrast allergy or renal disease.

Treatments

First, good medical control with cardiovasc risk fx interventions, exercise (key; functional improvement and adaptation), statins,
Aspirin; alternatively clopidogrel, not warfarin
Now several options for management
- indicated if lifestyle-limiting claudication, rest pain, tissue loss
Depends on methods of revascularization and extent of occlusive disease
Arteriobifem bypass was gold standard therapy; now endovascular
- balanced by risk factors, procedure durability, life expectancy,
--> in general: short and focal lesions (<3-4cm) by endovascular; longer more diffuse lesions (3-10cm) by surgery
- failure of endovascular predicted by poor infrainguinal runoff, external iliac disease, females, and CRF
- progressing toward more role for endovascular approaches.

Endovascular Approaches
First line in general
1. Diagnostic angiogaphy at time of intervention (CTA etc earlier)
- a 50-60% reduction in lumen = significant haemodynamic lesion
- can measure pressure across lesions using catheter pressures; resting gradient of 5mmHg significant; stress gradient 15mmHg is significant (200mg nitroglycine test)
2. Therapeutic heparinization with activated clotting time of 200-250s;
3. Predilate calcified sections with an undersized balloon
4. Pass stents when appropriate (based on lesion size, treatment effect and severity).
5. For lesions of aorto-iliac bifurcation, simulataneous angioplasty with a 'kissing-balloon' method
- now good stents available for iliac segments
- for external iliac, angioplasty and selective stenting
- can do hypogastric intervention (rarely) for buttock claudication / impotence.
- for infrarenal aortic stenosis, aortic angioplasty has poorer long-term outcomes; primary stenting has better results.
- for concomitant femoral disease, hybrid femoral endarterectomy and endovascular treatment is an option
--> don't place stents across inguinal ligament due to fracture and failure rates
6. Complications include access site issues, contrast nephropathy, cardiopulmonary events; overall rate <5%
- minimize nephropathy by good hydration and oral N-acetylcysteine
- in-stent restenosis or recurrent disease in 25% at 2 years.
--> surveillance with clinical reviews, exercise pulse recordings, ABI, duplex USS

Role of Surgery
Remains gold standard with excellent 5-year patency rates >85%
But riskier; only recommended when anatomy or lesions not amenable to endovsacular approaches

Aorto-bifem bypass
1. Exposure and control of femoral vessels
 - may need to take profunda distally for simultaneous profundaplasty
2. Aorta exposed by vertical midline incision
- bowel retracted lateral and caudial, ligamet of Treitz divided, 4th portion of duodenum mobilized to show L renal vein
- beware hypogastric nerves anterolateral to aorta and over L common iliac
3. Retroperitoneal tunnels using blunt finger dissection for graft passage
- beware ureters; want graft posterior or may get obstruction
- avoid veins / epigastric vessels around site of inguinal ligament
4. Sized dacron graft
5. End-end anastomosis; eliminates competitive flow through native system
- heparinized, clamps distal to L renal vein and proximal to IMA
- proximal anastomosis close to renal arteries to avoid failure secondary to disease progression
- infra-renal aorta resected to below bifurcation; stump oversewn
- proximal anastomosis with a running suture
- femoral anastomoses often carrying grafts to profunda.
Complications
Wound, graft, cardiopulmonary
- seroma, haematoma, infection; graft infection, thrombosis, pseudoaneurysms
- pelvic ischaemia rare but devastating; diarrhoea, acidosis, sepsis; need to rule out colonic ischaemia.
--> averted by end-side aortic anastomosis; alternatively one or both hypogastric arteries can be revascularized.

Femoropopliteal Occlusive Disease

Vascular between inguinal ligament and tibial vessels
- superifical femoral and popliteal afteries mainly.
- usually atherosclerosis
Clinical Evaluation
Presentation usually claudication, or limb-threatening ischaemia.
Pain with walking, rest? Where?
Ulcers / tissue loss?
Skin changes?
Degree to which symptoms are impairing normal quality of life is important.
Pulse exam is critical in localizing the vascular lesion.
- femoral just below inguinal ligament, but politeal / pedal diminished / absent
- most common site of occlusion is the
Identify and characterise lesions / non-healing ulvers / wounds, necrosis
Pallor on elevation of leg and rebur dependent is a sign of severe ischaemia
ABI
Imaging as above
Lesions then categorized by TASC classification system
image

Endovascular Management
As above.
Little doubt that they are less durable than surgical bypass, but balanced by lower invasiveness and risk.
- ie long term patency is not necessarily the critical factor; nonhealing ulcer repair, function etc.
Steps are:
1. Access arterial system; us. femoral
- sheath then placed to facilitate interventions.
2. Assess lesion with angiography
3. Cross the lesion with a guidewire
4. Treat with techniques: balloon agioplasty, atheromectomy, stent placement.
5. Completion angiography.
Selective stent placement as above.
Outcomes vary wrt type above; repeat interveions often needed for more severe lesions.
- technical success in 95%, 2y patency 30-70%, highly related to classification type.

Surgical Management
Usually a bypass, occasionally enarterectomy for isolated selected lesions.
1. Exposure of common reformal through vertical or oblique incision; distal exposure of popliteal above or below knee through a medial incision of distal thigh / proximal lower leg.
2. Bypass conduit should be determined preoperative, with intraop confirmation.
- great saphenous vein is conduit of choice, alternatives are cephalic or basilic or short saphenous.
3. Heparinization, proximal anastosis, usually end-side with conduit and common femoral.
4. Tunnel connecting to site of distal anastomosis; graft passed
5. Distal anastomosis to popliteal below disease
6. Angiography to confirm patency / graft function.
Robust data avilable for expected outcomes; primary patency 30-90% at 5y
- depends on indication, conduit, quality of vein, extent of bupass, quality of runoff

Discussion 
Controversy remains over more appropriate treatment of C and D lesions;
- absence of good data; various approaches
- percutaneous first approach, surgical when it fails is reasonable.
- better morbidity, mortality, quality of life.

Tibioperoneal Occlusive Disease

General Considerations
Diabetes in 60%, calcified distal vessels that increase difficulty / options of intervention.
Multilevel disease further augments complexity; infrapopliteal collateralization prevents early disease recognition.
Frequent need for reintervention.

Assessment

Thorough history and physical; functional status; often old (mean age >70y) all have comorbidities.
- patient preop optimization whenever possible.
-however, no need for routine cardiac evaluation; delay is worse than benefit.
Physical exam includes bilateral pulses, wounds, infections, coexistant venous disease.
- if intervention planned, diligent control of foot sepsis as well; leave any open toe amputations to drain.
Noninvasive vascular imaging including ABIs
- ankle pressure <50 with flat pulse waveform indicates unlikely to heal foot wounds without revascularization.
More detailed imaging includes angiography, CTA, MRA.
- number of patent vessels correlates with success chances.
- restoration of flow for healing requires at lease one continuous vessel in line to the foot.
--> if not, need to revascularize to restore such a vessel.
If the patient is a candidate for distal bypass, noninvasive evaluation of venous system should be done to look at bypass conduits.
- also upper arms if required for suitable bypass veins.
Consider primary amputation if nonambulatory, limited functional status, flexion contractures, prohibitive medical risks and lower extremity infections.

Treatment
Acutely threatened limbs:
- may benefit from systemic heparinization or thrombolytics prior to operative / endovascular intervention.
- judgment call, depends on acuity of symptoms and severity of ischaemia
Aspiriin and adenosine diphosphate receptor inhibitor (either clopidogrel or dipyridamole) initiated 5d prior to elective endovascular interventions.
- also routine start bypass patients on aspiring and clopidogrel preoperatively.

Tibial Artery Bypass
Bypass to posterior tibial, anterior tibial or peroneal vessels
- alternatively, to the pedal vessels of the foot.
All things considered, the most disease-free proximal vessel that can provide in-line flow to the foot is chosen.
Inflow?
Choice determined by prior interventions, characteristics of inlow vessel, length of available vein
- usually common femoral; alternatively, any one of distal external iliac, profunda femoris, superficial femoral, or above the knee popliteal.
Make a tension free anastomosis, avoid future pseudoaneurysms.
Autogenous veins is the preferred conduit.
- order of preference: greater saphenous, lesser saphenous, followed by arm veins (thinner walled, often have fibrotic segments from venipuncture and lower patency rates)
- may be reversed or used in-situ;  regardless, 3mm diameters recommended.
- ligate side branches, in-situ technique requires lysing venous valves.
- use of prosthetic grafts not recommended below knee because both patency and limb-salvage lower than in a long vein, but considered if no alternative.
Procedural details
1. General, spinal or epidural, monitoring
2. Inflow and outflow vessel exposure depending on plan.
- tibioperoneal trunk exposed medially; incise muscular fascia, retract medial head of gastrocnemius posteriorly; divide if required.
- proximal tibial exposed by separation of soleus from tibia
- mid posterior tibial artery is preferred target for distal bypass; runs between tibailis posterior and flexor digitorum longus
- distally, the posterior tibial artery exposed through a longitudinal incision posterior to the medial malleolus, splitting distance between malleous and tenon.
- anterior tibial artery exposed along its length by an incision 2cm lateral to tibia; dividing fascia of anterior compartment, bluntly separate tibialis anterior and flexor digitorum longus
---> see Cameron page 786 for operative anatomy

Endovascular treatment
Same indications as for surgical bypass
- but evidence base suggests intrapopliteal procedures should be reserved for limb salvage in appropriate candidates.
- avoid these treatments for claudication resolution; unsuccessful therapy may worsen symptoms and induce critical ischaemia and limb loss
Excellent alternative to surgery when pts unsuitable for bypass
- e.g. poor vein options, high risk.
- or as temporizing procedure for augmenting inflow / outflow.
--> contributes to an overall substantial decrease in major amputation rates.
Balloon angio is most common intervention here; single short segment stenoses usually.
- less likely to respond if occlussive, long-segment, multiple lesions, heavily calcified.
- stents with balloon angio suboptimal.
Long term patency uncertain, but technical success ~80%, limb salvange 50-84% at 2-5y

Post-op treatment ans surveillance
Aspirin and plavix after procedures should be considred.
Surveillance with ABIs at 1m, 3m, 6m ,1y and annually thereafter
- decrease in ABI of 0.15+ is concerning or increase in focal velocity at anastomoses wor within grafts should prompt further imaging.
Early failures are due to optechnical errors, dissection, emboli, prevented by intraop imaging and recognition
- most with early graft failures will require surgical reinterventions.
Technical feailures at 1m-2y mostly neointimal hyperplasia
Follow with clinical exam, DUS imaging of treated artery and ABIs.
Reintervention when recurrence of critical ischaemia.

Profunda Femoris Disease

Primary fx of profunda femoris is to supple to large muscles of the thigh...
... but also provides flow to the leg via numerous collaterals.
When there is occlusion of the sFA, the profunda provides flow to the entire lower leg.

Anatomic Considerations
Originates at femoral bifurcation, 3-5cm below fhte inguinal ligament.
- varies; can be at the ligament or 5cm+ below it.
- look at imaging pre-procedurally.
Branches posterolaterally, forming an acute angle with the superficial femoral artery.
When dissecting, note the change in claiblre of the common to superficial femoral as a clue.
Crossed anteirorly by the circumflex femoral vein at bifurvation.
- potential site of fistula during percutaneous endovascular procedures
Divided into 3 zones from anatomic landmarks:
- proximal = at profunda takeoff to lateral femoral circumflex artery origin
- middle = at lateral femoral circumlex to takeoff of second perforator (in adductor longus, anterior to brevis and magnus
- distal = from 2nd perforator to 4th perforator.
image


Evaluation
Difficult to examine clinically; femoral can be palpable despite a big embolus at the bifurcation
Important to evaluate in all imaging evaluations.
Can evaluate PVRs in SFA disease to assess profunda collateral flow.
Duplex helpful.
CTA, MRA.

Indications for intervention and technique
Usually not isolated involvement with atherosclerosis
Disease often at orifice and proximal portion in continuity with SFA / common disease
Have claudication, rest pain, tissue loss; often multi-vessel cause.
Profundaplasty performed as isolated procedure or adjunct to inflow / outflow procedures to help collateralisation.
- may experience a marked improvement in walking or rest pain after profundaplasty alone.
May be used as a source of inflow for a more distal bypass
May be used as outflow for femoral bypass

Exposed via vertical groin incision, surface landmark of inguinal ligament and pulse; followed as below.
Dissection along anterior surface, lateral femoral circumflex vein ligated; avoid injuring the arterial branches
Delicate artery: must be careful.

Vascular Claudication

Overview
Extremely common problem;
Anyone >40y with ABI < 0.9 has significant PAD
- although >50% have no symptoms; asymptomatic chronic subclinical ischaemia
Patient-oriented personalized endpoints critical for appropriate management
Balance risk of intervention against symptoms and natural history of disease.

Medical Management
PAD / claudication is a general marker of bad vessels; cardiac death 3-5% per year
Medical therapy benefits all of this.
Revascularization only indicated when medical therapy has failed
Cardiovascular risk modification is central
- smoking cessation; likely improves walking distances and slows progression
- diabetic control; each 1% increase in HbA1c associated with 25% increased risk for PAD; aim <7
- control HTN; 2-3x risk of PADaim <140/90 or <130/80 if diabetes / CRF
- Reduce cholesterol; statins improve ABI, walking performance, symptoms; strong LDL/HDL improvement = substantial benefit
- supervised exercise training / walking programs; min 30-45m, 3-4x per week for offers proven benefit in claudication.
- need a statin, aspirin (for CV mortality risk).

Natural Hx
image


Surgical Management
Medical management only effective in 1/3, endovascular therapy has improved management options for all
- lower morbidity lower mortality, easier on patients, and though lower patency rates, repeat procedures often well tolerated when needed.
Open bypass operations increasingly replaced by outpatient angioplasty with return to work in 48h
Interventions must be focused on patient-oriented outcomes; ie symptoms relief and quality of life paramount.
- ie traditional endpoints of technical success, limb salvage and patency are insensitive
- e.g. better to focus on degree of exercise-induced leg pain.

Foot Gangrene
Both dry and wet occur in presence of arterial occlusion
- dry = no bacterial infection; mummification and demarcation of necrotic tissue
- wet = area acutely infected and swollen
--> rapid tissue decay accompanied by systemic symptoms and pain.

Dry does not require immediate amputation; instead auto-amputation may occur alleviating the need
- may take months while epitheliazation occurs under the gangrenous eschar.
Wet requires urgent evaluation for revascularization and amputation as reqd.

Epidemiology / Risk Fx
Usual chronic microvascular and macrovascular disease, smoking, HTN, and diabetes
Mostly unilateral; bilateral in specific systemic conditions.

Evaluation
Thorough history and exam, identify preexisting conditions.
Level of amputation determined empirically by thorough history and physical.
- look for changes of kin (color, atrophy), pulses and bruits,
Etc
Diagnostics with ABI, doppler, pulse volume recordings.
Note that the disease is due to macrovascular disease but ability to recover after revascularization depends on an adequate microcirculation.
- can assess microcirculation with the toe-brachila index; uses photplesthymography
- normally toe pressure ~30 mm Hg less than highest brachial pressure (TBI 0.7 = normal)
- Toe pressure <50 mm Hg in acute gangrene or <30 under non-ulceration = critical ischaemia
Imaging with Angiography, MRA, duplex US (Major modality, high sensitivity / specificity).

Management
1. Antibiotics and medical management
- polymicrobial infections, need to cover aerobic, gram +ve cocci staph strep,
- B-hemolytic strep and Staph in diabetic wounds: more virulent, be more aggressive.
2. Debridement of deviltalized tissue when infected.
- shart debridement
3. Revascularization of the leg.