Armando Hasudungan
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Peripheral Arterial Disease (Chronic Lower Limb Ischaemia)

This section focuses on Limb Ischaemia as a result of peripheral vascular disease (chronic limb ischaemia)

Lower Limb Ischaemia

Overview

Overview

Definition
Ankle-Brachial Index (ABI): Ratio of ankle to brachial systolic blood pressure, determined using Doppler ultrasound flow.
Claudication: Pain, ache, or cramp in muscles that increases with walking or leg exertion in a predictable manner and resolves with rest.
Peripheral arterial disease: Atherosclerosis leading to narrowing of the major arteries distal to the aortic arch. It can involve both the upper and lower extremities
Acute Limb ischemia: Sudden decrease in the blood flow to a limb, resulting in a potential threat to the viability of the extremity
Chronic Limb ischaemia: Peripheral vascular disease
Critical Limb ischaemia: severe obstruction of the arteries which markedly reduces blood flow to the extremities (hands, feet and legs) and has progressed to the point of severe pain and even skin ulcers, sores, or gangrene. T

Classification

FONTAINE STAGE CLASSIFICATION OF PVD
Stage I Asymptomatic, decreased pulses, ABI <0.9
Stage II Intermittend claudication
Stage III Daily rest pain
Stage IV Focal tissue necrosis

Risk Factors

Risk Factors
Cardiovascular risk factors
Atrial fibrillation
Recent MI
Aortic athersclerosis
Aneurysm
Prior vascular surgery
Deep vein thrombosis (paradoxical embolism)

Risk Factors The most important risk factors for PAD are cigarette smoking and diabetes mellitus. Hypertension, dyslipidemia, and elevated homocysteine levels also play significant roles.

Clinical Manifestation

Peripheral arterial disease is atherosclerosis leading to narrowing of the major arteries distal to the aortic arch. Progressive occlusion results in arterial stenosis, reduced blood flow, and claudication, the most common presenting symptom


Examination – The 6 P’s

  • Pain (absent in 20% of cases)
  • Pulse
  • Pallor (within a few hours becomes mottled cyanosis)
  • Pressure (pain on stretch, firm, tense)
  • Paresthesia
  • Paralysis

Physical examination findings may include cool skin; nonpalpable distal pulses; auscultation of bruits over the iliac, femoral, or popliteal arteries; abnormal capillary refill time; nonhealing wounds; shiny skin; absence of hair in the affected area; and distal extremity pallor on elevation

Differential Diagnosis

Differential diagnosis of Claudication

  • Arthritis
  • Chronic compartment syndrome
  • Muscle strain
  • Baker’s cyst
  • Nerve entrapment
  • Nerve root compression
  • Spinal stenosis
  • DVT
  • Vasculitis
DIFFERENCES BETWEEN TYPES OF CLAUDICATION
Arterial – Intermittent (atherosclerosis) Neurogenic (Lumbar spinal stenosis) Venous (Deep vein thrombosis)
Pain Pain is in the muscle of the calf, thigh or buttock Pain is in whole leg ca be associated with tingling and numbness Involvement of whole leg. Patients may describe feeling their leg is going burst
Unilateral or Bilateral Unilateral in femoropoliteal disease. Bilateral in aortic-iliac disease Bilateral Most commonly unilateral
Provoking facotrs Gradual onset after walking “claudication distance” Comes on suddenly on standing or walking Gradual onset after beginning to walk
Relieving factors Pain is relieved by rest Relieved by sitting down, bending over and stopping walking Relief on elevating the leg
Unable to straighten legs
Pulses/ABIs Absent/reduced pulses Absent/reduced pulses Normal
Skin and tissue changes Mottled skin, Gangere Absent Cyanosed, Oedematous

Investigations

  • FBC
  • Serum glucose
  • β-hCG
  • Coagulation profile
  • Lipid profile
  • Ultrasound (Colour-duplex ultrasound)
  • CT – needs to be done before surgery
  • Surgery

When peripheral artery disease is suspected, the test most commonly used to evaluate for arterial insufficiency is the ankle-brachial index (ABI). Normally, blood pressures in the large arteries of the legs and arms are similar. In PVD this is different.

Reference Values of ABI
Ankle pressure is somewhat high ≥1.30
Normal 1.00 – 1.29
Borderline normal 0.91-0.99
Mild peripheral vascular disease 0.41-0.90
Severe peripheral vascular disease ≤0.40
Think In diabetic vessels there are calcification of arteries. This means it can give false ABI readings. Thus different sites of compression (toes) are used.
Ankle-brachial index is the ratio of the ankle blood pressure to the highest brachial systolic pressure. Ankle blood pressure is obtained by inflating a blood pressure cuff above the ankle and detecting the return of the dorsalis pedis or posterior tibial artery pulse by Doppler ultrasonography as the cuff is slowly deflated

Diagnosis clinical history and physical examination findings may suggest a diagnosis of PAD, especially in patients with multiple risk factors or classic claudication + Ankle-brachial index.

Management

Management of Chronic Limb Ischaemia

  • Lifestyle Modification
  • Control Blood Pressure
  • Analgesia
  • Statin
  • Antiplatelet therapy (to reduce risk of cardiovascular events)
  • Surgery
    • Angioplasty +/- Stenting
    • Endarterectomy
    • Bypass

Prognosis

  • 70% to 80% had stable claudication
  • 10% to 20% had worsening claudication
  • 1% to 2% progressed to critical limb ischemia over five years.
  • The rate of limb amputation at five years is estimated to be 1% to 4%

Acute Limb Ischaemia

Overview This section will mainly focus on acute limb ischemia, which is any sudden decrease in limb perfusion that causes a potential threat to viability. Patients who present later than two weeks after the onset of the acute event are considered to have chronic limb ischemia. Surgical thromboembolectomy and bypass grafting were the mainstays of therapy for many years. Subsequently, thrombolytic therapy and percutaneous transluminal angioplasty (PTA) have become treatment options for selected patients. Despite these advances, the morbidity, mortality, and limb loss rates from acute lower extremity ischemia remain high

Aetiology

Acute thrombosis in a vessel with existing atherosclerosis (60%)

Emboli (30%)

  • Cardiac cause (ie. Atrial fibrillation) (80%)
  • Aortic Aneurysm

Rare causes

  • Aortic dissection
  • Trauma

causes copy


Examination – The 6 P’s

  • Pain (absent in 20% of cases)
  • Pulse
  • Pallor (within a few hours becomes mottled cyanosis)
  • Pressure (pain on stretch, firm, tense)
  • Paresthesia
  • Paralysis
ASSESSING SEVERITY BASED ON EXAMINATION
Pain/Pressure Pulse Pallor Parasthesia Paralysis
Non-viable  Variable/ Woody hard muscle Absent Fixed mottling of skin Complete deficit Profound/ Complete
Threatened Severe/ Tender to touch (swollen) Absent Blue – Pale Partial deficit Partial
Viable Mild Present Pale No sensory deficit None

Management

Remember Patients will usually have co-excisting coronary, cerebral, or renal disease

Resuscitation Acute Limb Ischaemia- Emergency

  • Oxygen
  • Fluids IV
  • Analgesia IV
  • Call for senior help
  • Assess severity (6 P’s)
  • IV Heparin (check APTT every 4-6 hrs), aim for target time of 2-2.5x normal range
Remember Acute arterial occlusion that threatens limb viability is a medical emergency and requires immediate anticoagulation and investigation with conventional arteriography.

Definitive Management (Depending on severity)

  • Nonviable – amputation
  • Threatened – manage sign/symptoms of muscle necrosis (hyperkalaemia, acidosis, ARF and cardiac arrest). Identify cause (ie. atherosclerosis).  Surgery to revascularise and perform fasciotomy if need to prevent compartment syndrome. Consider amputation if ischaemic changes advanced and life-threatening.
  • Non- threatened – Initiate thrombolytic treatment. Surgery and revascularisation will most likely be required.
Remember Smoking cessation is the single most important intervention for atherosclerotic peripheral vascular disease. Other treatments include pentoxifylline or cilostazol, regular exercise, and cardiovascular risk factor modification.

Acute vs. Chronic limb Ischaemia (PVD)

  Acute Chronic
 Aetiology Sudden obstruction of an artery due to an embolus or thrombosis. Slowly progressing disease process that is usually due to atherosclerosis causing obstruction
 Claudication  No history Usually Present
 Site Lower extremity Lower extremity
 Management  Urgent as limb can progress to irreversible ischaemia and myonecrosis within 6 hours.  Conservative and surgery if  severe lifestyle impairment, vocational impairment, critical ischemia
Prognosis ~15% mortality and up to 40% morbidity (amputation Claudication therapy (60-80% improve, 20-30% stay the same, 5-10% deteriorate, 5% amputation). For patients with critical ischemia high risk of amputation (carries 25% risk of death at 1 year)

References

Oxford Handbook of Clinical Surgery
Oxford Handbook of Clinical Medicine
Toronto Essential Notes
Hennion, D. & Siano, KA. (2013). Diagnosis and Treatment of Peripheral Arterial Disease. American Family Physician. 88(5). 306-310.