Peripheral Arterial Disease (Chronic Lower Limb Ischaemia)

» Vascular Surgery

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)