subintimal angioplasty in diabetic patients with critical lower limb ischaemia.
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Nydahl S, Hartshorne T, Bell PRF, Bolia A, London NJM.
Subintimal angioplasty of infrapopliteal occlusions in critically ischaemic limbs.
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Vraux H, Hammer F, Verhelst R.
Subintimal angioplasty of tibial vessel occlusions in the treatment of critical limb ischaemia: mid-term results.
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Ingle H, Nasim A, Bolia A, et al.
Subintimal angioplasty of isolated infragenicular vessels in lower limb ischaemia: long-term results.
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21 Peripheral Vascular Disease and Reconstruction Malcolm Simms
THE PROBLEM In Western society, the prevalence of symptomatic peripheral arterial occlusive disease (PAOD) producing intermittent claudication (IC) in men and women aged 55, 74 years is 4.5%,1 with people with diabetes being twice as susceptible as non-diabetics.
In non-diabetic claudicants, the natural history of PAOD usually pursues a benign course with only 25% deteriorating over a 5-year period, 5% requiring vascular reconstruction and only 2% progressing to am- putation.
Continued smoking trebles the risk of disease progression.2 Rather than suffering limb-related problems, the major hazard to which claudicants are subjected is mediated by the associated systemic atherosclerosis, with its attendant risk of heart attack and stroke, pro- ducing an increase in 5-year mortality from 5 to 30%.
Risk factors other than smoking and diabetes include hypertension,3 hyperlipidaemia4 and hyperhomocysteinaemia.5 The onset of symptomatic atherosclerosis tends to arise a decade later in women than in men.
In the diabetic population, the onset of PAOD is particularly sinister, since the risk of progression to amputation increases tenfold, to 20%.
In the United Kingdom, 40% of all patients undergoing major limb amputation are people with diabetes, of an annual total of 15 000 operations performed.6 Five years after amputation, only 50% of people with diabetes will be alive and only 20% will retain one intact leg.
The anatomical distribution of occlusion in the peripheral vasculature varies according to the risk factors implicated in its causation; thus smoking, hyperlipidaemia and male sex all favour iliac artery involvement,7,8 smoking in both sexes is associated with femoro-popliteal disease 9,10 and in people with diabetes the infrapopliteal arteries are the most affected.11−15 The systemic complications of diabetes that concern interventionists are addressed else- where in this book.
However, the pernicious trilogy of neuropathy, impaired tissue regener- ation and increased infectivity that threatens the feet of people with diabetes supports the generalisation that ‘every diabetic foot needs a pulse’.
PRESENTATION AND EVALUATION OF PAOD IN DIABETES Although palpation of ankle pulses should ideally be incorporated into diabetic clinic routine, the exercise is accurate and reliable in experienced hands only. Such hands, by definition,
The Foot in Diabetes, 4th Edition. Edited by Andrew J.M. Boulton, Peter R. Cavanagh and Gerry Rayman. C 2006 John Wiley & Sons, Ltd. ISBN: 0-470-01504-7
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PRESENTATION AND EVALUATION OF PAOD IN DIABETES 251
belong to trained clinicians who usually have other demands on their time.
Consequently the development of PAOD in people with diabetes may be overlooked until the onset of symptoms prompts its detection.
In contrast to the generality of PAOD sufferers, IC is an uncommon presenting symptom in people with diabetes.
The calf muscles that are most active during walking derive their blood supply from geniculate arteries that arise proximal to the popliteal trifurcation, and these are of- ten spared in diabetic-pattern PAOD.
Occlusion of the tibio-peroneal trunk and crural arteries is more likely to cause ischaemia at ankle and foot level.
Although foot claudication is sometimes complained of by PAOD sufferers with a distal pattern of occlusion, in people with diabetes this symptom is likely to be obscured by peripheral neuropathy.
As a result, the initial detection of PAOD in people with diabetes is often prompted by the onset of cutaneous trophic changes such as corns, calluses, blisters, ulcers or frank digital gangrene.
Podiatrists and diabetic nurses are trained to investigate early phenomena, but uninformed patients may ignore what they see as minor problems until they become incapacitated, by which time the limb may be unsalvage- able.
Loss of skin integrity can be followed by rapid bacterial colonisation, particularly in the presence of interstitial oedema, and localised cellulitis can quickly progress to pyonecrosis.
Clinical Evaluation In the majority of vascular patients, prognosis and therapeutic strategy can be determined clinically.
Experience has shown that IC points to disease arising from a single anatomical level, whilst chronic critical limb ischaemia (CLI), characterised by rest pain or trophic change, requires disease to affect two or more levels.
Proximally these levels comprise the aortic, iliac and femoral bifurcations and the superficial femoral artery (SFA) at the adductor hiatus.
Below the knee, the relevant levels are the popliteal trifurcation, the malleolar anastomosis and the pedal arch.
Reversal of symptoms requires restoration of flow across the appropriate number of levels.
Thus, with a symptomatic history and careful mapping of pulses, it is possible to predict the urgency and likely extent of any revascularisation, as follows.
Femoral pulse palpation provides a reasonably accurate assessment of the adequacy of aorto-iliac inflow.
The detection of obvious calcified plaque in the femoral artery by pressing firmly and rocking the fingertips from side to side is a reliable pointer to the presence of further calcification in the distal arterial tree.
Palpation of the popliteal pulse has considerable clinical significance; a strong pulse in the presence of CLI in the foot implies that there must be occlusion at trifurcation and malleolar levels, and so curative intervention will have to extend to the foot.
Clinical accuracy in popliteal artery assessment is impaired by oedema and vascular calcification.
When an absent popliteal pulse coincides with ischaemic trophic change in the foot, the popliteal trifurcation is probably diseased but the calf arteries are likely to be spared.
If CLI is observed in the presence of a palpable ankle pulse, it is likely that the arteries of the foot are too extensively diseased for revascularisation to be profitable and that conservative treatment should be preferred.
Unfortunately, CLI is a concept that resists measurement, particularly in people with dia- betes.
The 2000 TransAtlantic Inter-Society Vascular Consensus Document defines it as rest pain, ulceration or gangrene attributable to objectively proven PAOD, predicting the need for major amputation within 6 months in the absence of successful intervention; ankle pressures should be below 50 mm Hg and toe pressures below 30 mm Hg.16 Despite this apparently sim- ple concept, publications describing vascular interventions for purported CLI do not routinely