Vascular Surgery

Question 1

Clinical features of acute arterial ischemia?

Answer 1

6Ps- all may not be present
• Pain: may be constant or elicited by passive movement
• Pallor: pale within a few hours becomes mottled cyanosis
• Paresthesia: light touch lost first then other sensory modalities
• Paralysis/Power loss: most important, heralds impending non-salvageable limb
• Polar/Poikilothermia: cold leg becomes cold
• Pulselessness: helpful to determine site of occlusion

Question 2

Urgent management required as skeletal muscle can tolerate ___ of total ischemia before irreversible damage

Answer 2

6 h

Question 3

Definition of acute arterial ischemia?

Answer 3

Acute occlusion of a peripheral artery that often threatens limb viability

Question 4

Suspect embolism in patients with the following features

Answer 4

• Acute onset (patient able to accurately recall the moment of the event)
• History of embolism
• Known embolic source (e.g. cardiac arrhythmias)
• No prior history of intermittent claudication
• Normal pulse and Doppler in unaffected limb

Question 5

Embolism vs. thrombosis

Answer 5

• Thrombosis is more common than embolism; usually in superficial femoral artery
• Existing atherosclerotic plaques can rupture causing thrombosis
• Previous vascular grafts/reconstructions can fail and thrombose leading to acute presentation
• Hypercoagulable states can contribute to thrombosis
• Embolism generally results in greater degree of ischemia due to lack of collaterals

Question 6

Risk factors of embolism?

Answer 6

• Cardiac: arrhythmias, endocarditis, MI, LV aneurysm, myxoma/cardiac tumour, paradoxical embolism, valvular heart disease
• Non-cardiac: mural thrombus within arterial aneurysms, atheroembolism

Question 7

Risk factors of thrombosis?

Answer 7

• Atherosclerotic obstruction
• Vasospasm
• Aortic or arterial dissection
• Arterial transection

Question 8

Investigations of acute arterial ischemia?

Answer 8

• Determine Rutherford classification based on physical findings and Doppler signals
• Ankle Brachial Index (ABI)
• ECG, troponin: rule out recent MI or arrhythmia
• CBC: rule out leukocytosis, thrombocytosis or thrombocytopenia in patients receiving heparin (may suggest HITS)
• PT/INR, PTT: patient anticoagulated/sub-therapeutic INR
• Echo: identify wall motion abnormalities, intracardiac thrombus, valvular disease, aortic dissection (Type A)
• CT angiogram: identify underlying atherosclerosis, aneurysm, aortic dissection, identify embolic source, identify other end organs with emboli (e.g. splenic/renal infarcts), identify level of the occlusion and extent
• Angiography: can be obtained in OR as part of intervention or for treatment planning

Question 9

Rutherford ALI Category I Visible description?

Answer 9

Not immediately threatened

Question 10

Rutherford ALI Category IIa Marginally description?

Answer 10

Salvageable if promptly treated

Question 11

Rutherford ALI Category IIb Immediately description?

Answer 11

Salvageable with immediate revascularization

Question 12

Rutherford ALI Category III Irreversible description?

Answer 12

Major tissue loss or permanent nerve damage inevitable

Question 13

Rutherford ALI Category I Visible findings?

Answer 13

Sensory Loss: None
Muscle Weakness: None
Arterial: Audible
Venous: Audible

Question 14

Rutherford ALI Category IIa Marginally findings?

Answer 14

Sensory Loss: Minimal or none
Muscle Weakness: None
Arterial: Inaudible
Venous: Audible

Question 15

Rutherford ALI Category IIb Immediately findings?

Answer 15

Sensory Loss: More than toes, associated with rest pain
Muscle Weakness: Mild, moderate
Arterial: Inaudible
Venous: Audible

Question 16

Rutherford ALI Category III Irreversible findings?

Answer 16

Sensory Loss: Profound, anesthetic
Muscle Weakness: Profound
Arterial: Inaudible
Venous: Inaudible

Question 17

Complications of acute arterial ischemia?

Answer 17

• Local: compartment syndrome with prolonged ischemia; requires 4-compartment (anterior/lateral/superficial and deep posterior) fasciotomy
• Heart: risk of arrhythmia, MI, cardiac arrest and death with reperfusion injury
• Kidneys/other organs: renal failure and multi-organ failure due to toxic metabolites from ischemic muscle, rhabdomyolysis
• Up to 10% chance of metachronous embolism

Question 18

Treatment of acute arterial ischemia?

Answer 18

• Immediate heparinization with weight-based bolus (80 Units/kg) and continuous infusion to titrate PTT to 70-90s
• If impaired neurovascular status: emergent revascularization (Rutherford category IIb)
• If intact neurovascular status: may have time for workup (including CT angiogram)
• Identify and treat underlying cause
  • Embolus: embolectomy
  • Thrombus: thrombectomy ± bypass graft ± endovascular therapy
  • irreversible ischemia (i.e. Rutherford category III): primary amputation or palliation/comfort measures
• Continue heparin post-operatively, start oral anticoagulant post-operatively when stable x3mo or longer depending on underlying etiology and other comorbidities

Question 19

Intracompartmental etiology of compartment syndrome?

Answer 19

Intracompartmental
• Fracture (particularly tibial shaft or paediatric supracondylar and forearm fractures)
• Reperfusion injury, crush injury, or ischemia

Question 20

Extracompartmental etiology of compartment syndrome?

Answer 20

Extracompartmental: constrictive dressing (circumferential cast), poor position during surgery, circumferential burn

Question 21

What is compartment syndrome?

Answer 21

o Increased interstitial pressure in an anatomical compartment (forearm, calf) where muscle and tissue are bounded by fascia and bone (fibro-osseous compartment), with little room for expansion
o Interstitial pressure exceeds capillary perfusion pressure, leading to muscle necrosis (in 4-6h) and eventually nerve necrosis

Question 22

Pathogenesis of compartment syndrome?

Answer 22

Increased pressure from blood and intracompartmental swelling - Decreased venous drainage + Decreased lymphatic drainage - Intracompartmental pressure greater than perfusion pressure - Muscle and nerve anoxia - Muscle and nerve necrosis - Leaky basement membranes - Transudation into tissue surrounding compartment

Question 23

Investigations of compartment syndrome?

Answer 23

 Clinical diagnosis
 In children or unconscious patients where clinical exam is unreliable, compartment pressure monitoring with catheter (normal = 0 mmHg; elevated ,>30 mmHg or [measured pressure - dBP]<30 mmHg)

Question 24

5 Ps of Compartment Syndrome

Answer 24

• Pain: out of proportion for injury and not relieved by analgesics – Increased pain with passive stretch of compartment muscles
• Pallor: late finding
• Paresthesia
• Paralysis: late finding
• Pulselessness: late finding

Question 25

Most important sign of compartment syndrome is ______

Answer 25

Increased pain with passive stretch

Question 26

Most important symptom of compartment syndrome is ______

Answer 26

Pain out of proportion to injury

Question 27

Treatment of compartment syndrome?

Answer 27

 Remove constrictive dressings (casts, splints), elevate limb at the level of the heart
 Urgent fasciotomy
 48-72 h post-operative: necrotic tissue debridement + wound closure
 May require delayed closure and/or skin grafting

Question 28

Complications of compartment syndrome?

Answer 28

 Volkmann’s ischemic contracture: ischemic necrosis of muscle; followed by secondary fibrosis; and finally calcification - especially following supracondylar fracture of humerus
 Rhabdomyolysis, renal failure secondary to myoglobinuria