Vascular Surgery Flashcards

1
Q

Clinical features of acute arterial ischemia?

A

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

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2
Q

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

A

6 h

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3
Q

Definition of acute arterial ischemia?

A

Acute occlusion of a peripheral artery that often threatens limb viability

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4
Q

Suspect embolism in patients with the following features

A
  • 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
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5
Q

Embolism vs. thrombosis

A
  • 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
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6
Q

Risk factors of embolism?

A
  • Cardiac: arrhythmias, endocarditis, MI, LV aneurysm, myxoma/cardiac tumour, paradoxical embolism, valvular heart disease
  • Non-cardiac: mural thrombus within arterial aneurysms, atheroembolism
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7
Q

Risk factors of thrombosis?

A
  • Atherosclerotic obstruction
  • Vasospasm
  • Aortic or arterial dissection
  • Arterial transection
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8
Q

Investigations of acute arterial ischemia?

A
  • 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
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9
Q

Rutherford ALI Category I Visible description?

A

Not immediately threatened

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10
Q

Rutherford ALI Category IIa Marginally description?

A

Salvageable if promptly treated

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11
Q

Rutherford ALI Category IIb Immediately description?

A

Salvageable with immediate revascularization

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12
Q

Rutherford ALI Category III Irreversible description?

A

Major tissue loss or permanent nerve damage inevitable

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13
Q

Rutherford ALI Category I Visible findings?

A

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

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14
Q

Rutherford ALI Category IIa Marginally findings?

A

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

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15
Q

Rutherford ALI Category IIb Immediately findings?

A

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

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16
Q

Rutherford ALI Category III Irreversible findings?

A

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

17
Q

Complications of acute arterial ischemia?

A
  • 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
18
Q

Treatment of acute arterial ischemia?

A
  • 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
19
Q

Intracompartmental etiology of compartment syndrome?

A

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

20
Q

Extracompartmental etiology of compartment syndrome?

A

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

21
Q

What is compartment syndrome?

A

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

22
Q

Pathogenesis of compartment syndrome?

A

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

23
Q

Investigations of compartment syndrome?

A

 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)

24
Q

5 Ps of Compartment Syndrome

A
  • 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
25
Q

Most important sign of compartment syndrome is ______

A

Increased pain with passive stretch

26
Q

Most important symptom of compartment syndrome is ______

A

Pain out of proportion to injury

27
Q

Treatment of compartment syndrome?

A

 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

28
Q

Complications of compartment syndrome?

A

 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