Non-invasive imaging using duplex ultrasound scanning (combined ultrasonography and Doppler colour flow images), MR angiography (MRA) and CT angiography (CTA) has now superseded digital subtraction angiography due to improved quality of the imaging and safety.
Digital subtraction angiography (DSA) is performed by a catheter inserted into the femoral vessels (usually the contralateral vessel to allow retrograde insertion of the catheter into the aortic bifurcation). It is now usually only carried out as a combined procedure to allow angioplasty or stent insertion to improve blood flow. It has a small but significant complication rate when associated with non-invasive imaging, is expensive, time consuming and often requires an overnight stay tying up hospital beds.
answers
Clinical cases
CASE1.18– A 78-year-old man presents complaining of calf pain on
walking
A1: Whatisthelikelydifferentialdiagnosis?
⦁ Peripheral vascular disease ⦁ Spinal stenosis or sciatica
A2: Whatfeaturesofthegivenhistorysupportthediagnosis?
The most likely cause will be PVD caused by atherosclerosis to the vessels of the lower limbs. The site of stenosis or occlusion will affect the presenting symptoms. The proximal disease (e.g. common iliac) may produce buttock claudication on exercise as well as lower limb pain. The most common site to be affected is the obturator foramen (two-thirds of the way down the thigh). This produces classic intermittent claudication (IC). The important aspects to obtain are the distance walked before having to stop (remember that most patients and doctors are poor at judging this and that the distance will be longer on the flat rather than uphill), the time required for the pain to resolve and walking to recommence and an assessment of the nature of the problem (static or progressive).
Spinal stenosis causes a similar presentation, making differentiation between the two sometimes tricky. Lower limb pain from spinal stenosis tends to occur after varying distances and does not resolve within minutes of rest (unlike in IC). The subsequent distances may become shorter and the time for resolution of the pain increases. The patient may also complain of a ‘bad’ back with neurological symptoms.
A3: Whatadditionalfeaturesinthehistorywouldyouseektosupporta
particulardiagnosis?
The diagnosis may be supported by the fact that the individual has risk factors that predispose him to atherosclerosis and he may have other cardiovascular problems.
A4: Whatclinicalexaminationwouldyouperformandwhy?
A full cardiovascular and peripheral vascular examination should be performed. The lower limbs may show signs of muscle wasting, thinning of skin and loss of hair. Peripheral pulses may be felt in the groin but are absent distally. Gangrene and tissue loss (ulceration) would indicate critical ischaemia, a stage beyond intermittent claudication.
A5: Whatinvestigationswouldbemostusefulandwhy?
In an individual not showing signs of critical ischaemia or disabling claudication the investigations undertaken would be aimed at preventing disease progression and not treating the stenosis or occlusion. Bloods including full-blood count (for anaemia), U&Es, fasting cholesterol and random blood glucose. Ankle brachial pressure indices (ABPIs) may be recorded to allow quantitative comparison of future follow-up. But the majority of patients with stable claudication do not require any further investigation and are followed up clinically.
Peripheral vascular disease (PVD) 49
A6: Whattreatmentoptionsareappropriate?
Cardiac function should be optimized to decrease any ‘pump failure’ as a cause. Strategies to slow disease progression should be undertaken (cessation of smoking, statins, antiplatelet medication, good diabetic control and treatment of hypertension).
Regular exercise improves neovascularization and cardiorespiratory function and helps in weight loss. A structured exercise program is proven to improve outcomes for claudicants.
CASE1.19– The same man presents to A&E with an acutely painful leg
A1: Whatisthelikelydifferentialdiagnosis?
The patient appears to have developed acute limb ischaemia. This is commonly the result of either thrombosis of the diseased vessels or an embolus occluding the vessel. In a known sufferer of PVD, the most likely cause is thrombosis.
A2: Whatfeaturesofthegivenhistorysupportthediagnosis?
Remember the 6 P’s of acute limb ischaemia – pale, pulseless, painful, paralysed, paraesthetic and ‘punishingly cold’.
A3: Whatadditionalfeaturesinthehistorywouldyouseektosupporta
particulardiagnosis?
An acute thrombosis due to a ruptured atheromatous plaque is the likely diagnosis in this patient who has a chronic history of intermittent claudication. Acute thrombosis of a popliteal aneurysm may present with an acutely ischaemic leg. Patients may have a history of a popliteal aneurysm or have other aneurysmal disease present in the popliteal or femoral arteries and the abdominal aorta. Embolus should be considered in patients who have no previous PVD history, or who have normal pulses on the opposite leg. A source of emboli should be considered, such as patients with new onset atrial fibrillation or a recent myocardial infarction.
A4: Whatclinicalexaminationwouldyouperformandwhy?
An examination will need to assess the viability of the limb and the urgency for intervention. Sensory and motor function should be assessed and recorded. If the diagnosis is in doubt, ABPIs can be performed. The patient’s general state should be assessed because acute limb ischaemia is often a pre- morbid episode and surgical intervention may cause unnecessary suffering.
If considering bypass surgery, the peripheral veins should be noted (varicosities) as these are typically used for bypass grafts.
A5: Whatinvestigationswouldbemostusefulandwhy?
Imaging of the arterial anatomy with either CT angiogram or MR angiogram if time permits would be indicated. An on-table angiogram may be performed if radiologists are present. Duplex USS may also be used if more detailed imaging is not and can also be useful in determining the venous anatomy for a suitable conduit (but should not delay theatre).
In embolic cases, the source of emboli should be investigated using ECG, echocardiography or duplex for abdominal aortic aneurysm.
A6: Whattreatmentoptionsareappropriate?
Depending on the suitability, a bypass graft may be attempted to restore flow. If the limb is unsalvageable then an amputation may be required.