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Pathophysiology, Clinical Features and Diagnosis of Vascular Disease Affecting the Limbs
Introduction
The term ‘peripheral arterial disease’ (PAD) is often used to mean obstructive (‘obliterative’) disease of major lower limb arteries, causing ischaemia. However, a range of vascular disorders can cause symptoms in upper and lower limbs, including any disease of arteries, veins or lymphatics outside the heart. This chapter concentrates on lower limb vascular-related problems as they are much more common. Upper limb symptoms are outlined in Table 40.5 (p. 514).
Patients with vascular limb disorders may present to any medical specialty and some require urgent action, for example, acute limb ischaemia or a symptomatic abdominal aortic aneurysm. Thus all clinicians need to understand the principles of diagnosis and the scope and timing of treatment. This chapter covers the pathophysiology of limb vascular insufficiency, plus the details of history taking and examining patients with suspected vascular disease, and the process of reaching a broad, ‘first stage’ diagnosis.
Vascular Insufficiency of the Limb ( Table 40.1 )
Arterial insufficiency and venous insufficiency are common and may be either acute or chronic. Vascular disorders of the lower limb are caused mainly by atherosclerosis, arterial thromboembolism, aneurysms, complications of diabetes, and thrombotic and varicose disorders of the venous system. Some patients have arterial and venous conditions together.
Arterial insufficiency means inadequate arterial blood supply to a limb that can occur over hours or days (acute) or over months or years (chronic). Acute arterial insufficiency is frequently caused by an embolism, often of cardiogenic origin, that lodges at a bifurcation of a normal artery. The lack of collaterals means that the ischaemia is often severe and limb threatening. Acute limb ischaemia can also be caused by in situ thrombosis of an atherosclerotic plaque in a lower limb artery, or much less commonly, by thrombosis of a popliteal aneurysm ( Table 40.2 ) or an aortic dissection extending into the lower limb vessels.
TABLE 40.1
Pathophysiology of Arterial and Venous Insufficiency—the Clinical Consequences of Vascular Diseases Affecting the Lower Limb a
| Basic Disease | Pathophysiological Process | Clinical Manifestations |
|---|---|---|
| Atherosclerosis and Embolism Causing Ischaemia | ||
| Atherosclerotic narrowing of large distributing arteries | Arterial supply inadequate to supply muscles during exercise Arterial supply inadequate even at rest, with relative ischaemia of all tissues. Risk of pressure ulceration. Healing severely impaired Limb is critically ischaemic; risk of limb necrosis in 6–8 hours unless urgently revascularised Thrombotic occlusion of atherosclerotic artery; clinical features as acute critical ischaemia |
Intermittent claudication —muscle pain on walking, quickly relieved by rest Chronic severe ischaemia —rest pain in foot, worse at night. Onset chronic over weeks or months. Skin pale/red/purple Acute-on-chronic ischaemia —sudden onset (within 2 weeks) of acute ischaemia in patient with a previous history of chronic ischaemia |
| Embolism from heart Mitral stenosis with left atrial thrombus; atrial fibrillation; endocarditis; recent MI Embolism from an aortic aneurysm |
Masses of thrombus detach and impact at arterial bifurcations, occluding flow | Acute severe ischaemia of upper or lower limb, brain or intestine. |
| Diabetes Mellitus | ||
|---|---|---|
| The ‘diabetic foot’ (imprecisely known as the neuroischaemic foot ) | Accelerated atherosclerosis and neuropathy. Loss of sensation predisposes to injury and ulceration and failure to heal because of ischaemia | Foot lesions (often painless)—deep ulceration in pressure areas, necrotic toes. Assume atherosclerotic ischaemia unless foot pulses palpable. Infection spreads rapidly, with potential limb-threatening necrosis and systemic sepsis. Needs early and vigorous treatment |
| Lesions often complicated by pyogenic infection | Response to infection impaired in diabetics | |
| Venous Disorders | ||
|---|---|---|
| Thromboembolism Acute deep venous thrombosis (DVT) May be complicated by pulmonary embolism |
Spontaneous thrombosis in deep veins of calf or thigh; may propagate to iliofemoral veins Obstructs venous return causing swelling and warmth. Venous gangrene in extreme cases, which requires early treatment often with thrombolysis. |
Pain and swelling of calf and ankle , often with calf tenderness, but often asymptomatic without clinical signs. Thigh swollen if iliofemoral veins thrombosed. Associated with risk factors, particularly immobility. Leg usually blueish or normal colour |
| Chronic venous insufficiency Postthrombotic limb and venous eczema | Late complication of DVT Spontaneous recanalisation of occluded veins damages valves causing incompetence (reflux) and local venous hypertension Similar clinical features to those in gross superficial venous insufficiency in varicose veins |
Chronic brawny oedema of leg often with narrow ankle because of lipodermatosclerosis (‘champagne bottle leg’). Skin atrophic, scaly and pigmented and gaiter area above ankle vulnerable to chronic ulceration after minor trauma |
MI, Myocardial infarction.
a Aneurysms are covered in Chapter 42 and varicose veins and thrombophlebitis in Chapter 43 .
TABLE 40.2
Symptoms and Signs of Popliteal Aneurysm—different clinical consequences of a similar underlying disorder
| Clinical Presentation | Pathophysiology |
|---|---|
| Asymptomatic —pulsatile swelling in popliteal fossa discovered by patient, by chance or during examination of patient with vascular problem | Often part of multianeurysmal disease |
| Examine for other aneurysms— contralateral popliteal fossa, abdomen, femoral arteries | |
| Acute ischaemia | Thrombosis of aneurysm or distal embolisation of clot from within aneurysm |
| Chronic ischaemia | Gradual occlusion of aneurysm or arterial runoff by thrombus or atherosclerosis. Similar symptoms to those in atherosclerotic disease |
| Apparent deep venous thrombosis (DVT) —swelling, cyanosis of leg | Large aneurysmal swelling occludes popliteal veins. May lead to DVT |
| Rupture of aneurysm | Sudden pain and swelling behind knee; swelling and pain in leg—often misdiagnosed as a DVT; occasionally evidence of distal ischaemia |
Symptoms and Signs in the Limb
Taking an accurate history is key to the diagnosis of lower limb vascular problems. This must include an assessment of major risk factors ( Table 40.3 ). Detailed history taking is covered in Table 40.4 and examination in Fig. 40.1 . In a suspected vascular case, the student or doctor tries to decide if the problem is arterial, venous or lymphatic, or has some other cause.
TABLE 40.3
Preliminary Assessment of the Vascular Patient for Obvious Risk Factors
| Factors to Assess First | Significance |
|---|---|
| Major Risk Factors for Arterial Disease—‘Gasd’ | |
| G ender | Men affected by atherosclerosis and aneurysms 10 years earlier than women |
| A ge | Peripheral atherosclerosis rare below 55 years—most common age 60–70 years. DVT unlikely below 20 years |
| S moking cigarettes | Risk of atherosclerosis proportional to ‘pack-years’ smoked; PVD unlikely in people who have never smoked |
| D iabetes (especially type 2) | Premature and accelerated atherosclerosis, predominantly more distally in limb. 25% of PAD patients are diabetic compared with 2%–3% of general population Peripheral neuropathies (sensory, motor and autonomic) Reduced resistance to infection |
| Other Risk Factors | |
|---|---|
| Hypertension | Predisposes to atherosclerosis, stroke and aneurysm expansion |
| Hypercholesterolaemia and hypertriglyceridaemia | Risk factors for atherosclerosis. Some inherited types have major adverse effects |
| Obesity and sedentary lifestyle | Difficult to quantify but likely to be significant factors |
DVT, Deep venous thrombosis; PAD, peripheral arterial disease; PVD, peripheral vascular disease.
TABLE 40.4
History Taking in Suspected Limb Arterial or Venous Disease
| History of Presenting Complaint | |
|---|---|
| Limb Symptoms | Important Features of the History |
Symptoms and signs
|
Detailed history of each symptom:
|
| Past Medical History | Important Features of the History |
| General cardiovascular history Peripheral vascular disease |
Venous or arterial thromboses; bleeding tendency |
| Arterial | Intermittent claudication; previous limb surgery—bypass operations; angioplasty; arterial thrombosis |
| Venous | Varicose veins/previous surgery; thrombophlebitis; DVT or pulmonary embolism; arm swelling; trauma + immobilisation, for example, lower limb fracture/treatment/ligament injury (predisposing to silent DVT) |
| Related history | In claudication—back problems and surgery (possible cauda equina claudication) Cervical rib; hypothyroidism Preexisting lymphatic disorder of limb (e.g., primary lymphoedema) |
| Cardiac Disease | |
| Manifestations | Ischaemic heart disease; (angina, MI) Heart failure (chronic lower bilateral limb oedema) Hypertension; valvular disease; arrhythmias |
| Interventions | Medication/thrombolysis Coronary angiography/angioplasty /pacemaker Coronary stent (type and length of dual antiplatelet therapy required) Cardiac surgery, for example, CABG; valve surgery, TAVI (transcatheter aortic valve implantation) |
| Cerebrovascular Disease | |
| Manifestation | Ischaemic/haemorrhagic stroke; transient ischaemic attacks (TIAs) |
| Interventions | Medication; carotid artery surgery/stent |
| Renal failure | Acute or chronic renal failure ± dialysis |
| Rheumatological disease | Collagen/vascular disease: Raynaud; rheumatoid disease Systemic sclerosis/scleroderma; other connective tissue disorders; vasculitis |
| Miscellaneous contributing factors | |
| Lower limb paresis or deformity | Predisposes to pressure ulcers: stroke or congenital spinal problems, for example, spina bifida |
| Haematological disorders | Thrombophilias, for example, thrombocythaemia, factor V Leiden mutation, antithrombin III, protein C or S deficiency; polycythaemia vera |
| Drug History | |
| Is patient taking: | Antihypertensives (ACE inhibitors, beta-blockers, calcium-channel blockers, diuretics); antiplatelet drugs (aspirin, clopidogrel, etc.) Anticoagulants (e.g., warfarin, DOAC—direct oral anticoagulant); a statin |
| Social History | |
| Smoking | Smoker/ex-smoker/passive smoker; how many pack-years |
| Exercise | Physically fit; regular exercise |
| Employment | Do symptoms impact on work; how does occupation impact on symptoms. Effect of claudication symptoms on quality of life is main indication for treatment |
| Family History | |
| Hereditary cardiovascular disease? | Cardiac, peripheral arterial disease, aneurysm, arterial or venous thrombosis |
ACE, Angiotensin-converting enzyme; CABG, coronary artery bypass grafting; DVT, deep venous thrombosis; MI, myocardial infarction.
The principal symptoms and signs of vascular disease are pain, changes in skin texture, colour and temperature, tissue loss including ulceration, and swelling. The upper limb is affected by a largely different range of disorders with signs and symptoms ( Table 40.5 ).
TABLE 40.5
Summary of Signs and Symptoms of Vascular Disease of the Upper Limb
| Sign or Symptom | Underlying Disorder | Other Clinical Features |
|---|---|---|
| Swelling of Arm and/or Forearm | ||
| Axillary vein thrombosis/Paget Schroetter syndrome Predisposing causes: Unaccustomed use of arm overhead, for example, decorating Excess weight lifting Cervical rib or congenital bands obstructing vein Too narrow a space between first rib and clavicle |
Blueness and heaviness of arm; later, prominent collateral veins over deltopectoral area. Symptoms usually abate spontaneously but early thrombolysis worth considering | |
| Colour Change | ||
| Acute whiteness or blueness | Embolism (causes as lower limb) | Acute ischaemia—hand cold, painful, loss of sensation and motor function |
| Trauma to brachial artery, for example, supracondylar fracture | ||
| White finger(s) | Raynaud disease (common): fingers go white then turn blue then red, often in response to cold. Because of vasospasm—pathogenesis unknown | Recurrent symptoms especially in cold weather May lead to atrophy of finger tips but rarely major tissue loss |
| Secondary Raynaud phenomenon (rare); underlying disorders include: Limited cutaneous scleroderma (CREST) Mixed connective tissue disease Sjögren syndrome Systemic lupus erythematosus Hand-arm vibration syndrome (HAVS) from use of vibrating tools |
As Raynaud disease | |
| Red painful fingers | Reflex sympathetic dystrophy posttrauma following fracture, especially forearm | Pain, redness, disability in arm |
| Pain | ||
| Vascular | Substantial subclavian arterial narrowing. Rarely symptomatic because of excellent upper limb collaterals | Muscle pain on exercise—arm ‘claudication’. Low systolic pressure |
| Acute ischaemia—most commonly embolism of cardiac thrombus; sometimes acute-on-chronic thrombosis (see acute ischaemia earlier) | Acute pain of vascular origin plus other features of ischaemia—pulselessness, pallor, paralysis, loss of sensation | |
| Neurovascular | Thoracic outlet syndrome—95% neurological symptoms, 5% arterial—lower trunk symptoms affecting C8/T1 most common. Rare and difficult to diagnose | Chronic pain—usually musculoskeletal but may be because of thoracic outlet syndrome |
CREST, Calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia.
Pain
Most limb pain is caused by musculoskeletal disorders, such as arthritis or by trauma rather than vascular disease. Where lower limb peripheral ischaemia is the working diagnosis, a full cardiovascular workup is needed (see Table 40.4 and Fig. 40.1 ).
-
Lower limb —patients may have itching and aching with varicose veins, or have exercise-related muscular cramp-like pain or severe and constant pain, initially in the toes and foot, caused by obliterative arterial disease. Where the history is short (<2 weeks), acute ischaemia may be the cause.
-
Upper limb —vascular-related pain is uncommon. Aching and swelling may be caused by subclavian or axillary vein thrombosis. Claudication is rare and acute ischaemia is usually because of embolism. Thoracic outlet syndrome is also rare. The brachial plexus may be compressed as it passes between the clavicle and first rib (or extra cervical rib) causing nerve root symptoms. Even less commonly, the condition may cause arterial or venous obstruction at the thoracic outlet.
Intermittent Claudication
Chronic lower limb arterial insufficiency usually presents as muscular pain on walking. The history is characteristic: pain begins at a reproducible distance, is worse walking uphill and increases if walking continues; the patient usually begins to limp , accounting for the name ‘intermittent claudication’ (Latin: claudicare to limp), and the patient is forced to stop. Symptoms usually predominate in one limb. The pain subsides within a minute or two of stopping and recurs at the same walking distance. Pain is almost always in the calf, whatever level the arterial obstruction, but may extend into thigh or even buttock in aortoiliac obstruction. If associated with impotence, this is known as Leriche syndrome .
After a thorough history, only cauda equina claudication or pseudo claudication might be mistaken for ‘true’ claudication. This is caused by compression of the cauda equina in the spinal canal by central disc protrusion or canal stenosis. Lower limb pain is also brought on by exercise, but there are important differences— Table 40.6 .
TABLE 40.6
Comparison Between Cauda Equina Claudication and Arterial Claudication
| Arterial Insufficiency | Cauda Equina Syndrome |
|---|---|
| History | |
| ‘Fixed’ claudication distance | ‘Variable’ claudication distance |
| Pain exacerbated by walking uphill | Pain often absent when walking uphill; often better when cycling |
| No history of low back problems | History of low back problems |
| Pain disappears after 1–2 minutes rest | Pain takes 15–30 minutes to subside |
| Examination | |
|---|---|
| Absent peripheral pulses and low ankle pressure in affected limb | Pulses usually present and ankle pressure normal |
| No evidence of a lower motor neurone (LMN) lesion | Evidence of an LMN lesion, such as diminished or absent lower limb tendon reflexes |
| Duplex ultrasound scan or arteriography shows arterial obstruction | CT or MRI scanning of the spinal canal is diagnostic, demonstrating a narrow spinal canal or disc protrusions impacting on the cauda equina |
CT, Computed tomography; MRI, magnetic resonance imaging.
Chronic Ischaemic Rest Pain
With more severe arterial obstruction, ischaemic pain occurs when the patient is in bed or even when sitting. Termed rest pain , this is usually felt in the skin and soft tissues of the foot and is very severe and burning. It occurs mostly at night because gravity assistance to arterial supply is lost, cardiac output falls at rest, and skin vessels dilate with warmth. The pain is characteristically relieved by hanging the leg out of bed or even walking around and is not fully relieved by any analgesics. Often, patients end up sleeping in a chair, causing lower limb oedema. Patients often present after tolerating this severe pain for several weeks. Only 10% of claudicants progress to rest pain.
There may also be skin changes or tissue loss, such as gangrene and ulceration (see later). The term critical ischaemia implies that loss of part of the limb is inevitable unless it is revascularised. Beware of the trap in diabetic patients with neuropathy— severe ischaemia may be painless . Disruption of small vessel autonomic control may mean a severely ischaemic foot is warm and red (often referred to as a sunset foot ) rather than cold and white or blue. In the absence of palpable pulses, imaging will help determine the severity of the ischaemia.
Acute Critical Ischaemia
This is of sudden onset, associated with severe pain similar to rest pain. However, if peripheral blood flow is very low, pain may be absent in the distal, most severely affected area, which becomes numb or has diminished sensation (paraesthesia) because of nerve ischaemia. Muscle paralysis is marked in severe ischaemia, as is muscle pain on moving the foot. It is vital to recognise acute arterial insufficiency quickly, as without timely treatment, it rapidly progresses to irreversible necrosis.
The cardinal clinical features of acute critical ischaemia are:
-
Pain —severe but variable in intensity, affecting distal part of limb.
-
Pallor —the ischaemic area is initially white but later becomes mottled (marbling) because of stagnation of deoxygenated blood. If this blanches on pressure, the limb is still viable. If the mottling does not blanch (fixed staining) then the limb is nonviable.
-
Pulselessness — foot pulses are absent and popliteal and femoral pulses may be lost, depending on level of arterial occlusion.
-
‘ Perishing’ coldness —most extreme at foot (or hand).
-
Paraesthesia (reduced sensation) or anaesthesia of the periphery. This only occurs if ischaemia is severe.
-
Paralysis of calf muscles. The patient is unable to flex or extend toes or ankle. This only occurs if ischaemia is extreme. Pain may disappear at this stage.
(As an aide-mémoire , these features are known as the six Ps: P ain, P allor, P ulselessness, P erishing coldness, P araesthesia, P aralysis. Not all are present all of the time; anaesthesia and paralysis are dire prognostic features and indicate that revascularisation is required immediately.)
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