procedure with success rates ranging from 79 to 91%.
There is a learning curve to the tech- nique, and we believe that with experience the primary success rates of recanalising occlusive disease of femoro-popliteal and tibial segment are nearer to 90%.
Secondly, whilst there is variability in the patencies at 1 year, ranging from the poor 33% at 1 year, to 65% at 5 years, there is marked consistency in the limb salvage rates of around 90% at 1 year and 88% at 3 years in one of the series.
It can be concluded that subintimal angioplasty even in the predom- inantly femoro-popliteal segment makes a significant impact on the treatment of critical limb ischaemia.
Table 20.2 shows that where the treatment has been directed exclusively to the tibial vessels alone, in patients where there was no significant supra-popliteal inflow disease, subintimal angioplasty provided equivalent results to those for the femoro-popliteal segments.
The primary success rates range from 78 to 86%, and whilst patency at 1 year averages 56%, limb salvage is consistently high from 81% at 1 year to 94% at 3 years.
The incidence of diabetes ranges from 33 to 72%35, 37 between the two sites of treatment, femoro-popliteal or tibial (Tables 20.1 and 20.2), and it can be concluded that subintimal angioplasty is an effective treatment and makes a substantial impact on the treatment of critical limb ischaemia.
Since a significant proportion of patients with critical limb ischaemia have diabetes, over 33% except for one series, it is not difficult to see that subintimal angioplasty is a highly effective mode of minimally invasive treatment for patients with diabetes with foot ulcers/gangrene and PVD generally.
COMPLICATIONS Angioplasty is not without morbidity or mortality although the incidence of the latter is very small.
In a large study by Axisa,38 1377 procedures were reviewed.
Emergency surgical interven- tion was required in 2.3%.
The overall amputation rate following angioplasty was 0.6%, but it was 2.2% for patients with critical limb ischaemia.
There was a 1.3% mortality at 30 days, the commonest cause being bronchopneumonia.
In patients with critical limb ischaemia, the mortality was higher at 4.9%.
The commonest complication of angioplasty is puncture site haematoma, the incidence of which has been reported up to 10%.
The vast majority of these are self-limiting, though occasionally the patient may require transfusion or even surgery, the incidence being less than 1%.
A more serious complication is when bleeding from the puncture site, usually from a high puncture, tracks in the retroperitoneal space.
Such an occurrence is not easily evident
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CONCLUSION 247
at the puncture site and may come to light only when the patient demonstrates symptoms of significant hypotension due to substantial blood loss.
Urgent attention is necessary to prevent mortality.
Rapid replacement of fluid/blood and surgical repair is warranted in these situations.
Fortunately, nowadays, closure devices are available that can be used to seal the puncture site when a high puncture has been made.
Peripheral embolisation following angioplasty occurs in less than 5% of patients; the ma- jority of the emboli can be aspirated percutaneously at the same time as the procedure.
The incidence of perforation of the arterial wall has been reported at 3.7% in a large series by Hayes39 comprising 1409 patients and 1532 limbs.
Patients who had perforation were more likely to be older (median age 74.8 years vs 69.6 years) and/or diabetic.
However, the perforation itself does not influence the ultimate outcome of the case.
Acute limb ischaemia can occur as a complication after attempted angioplasty, the incidence of which is <1.5%.
In the past, this situation would have required an urgent bypass operation, but nowadays, fortunately, the majority of cases can be retrieved using a long self-expandable stent to counter the elastic recoil of the vessel, which causes acute shutdown to the flow acutely.
THROMBOLYSIS Acute limb ischaemia occurs when a previously stenotic lesion progresses to an occlusion acutely, without adequate collateralisation around the stenotic lesion.
This would most com- monly occur in the femoro-popliteal segment.
Symptoms include pain, pallor, decreased sen- sation and a cold foot.
There are two strategies for the management of this acute situation.
If the limb is viable and not too threatened, it may be managed conservatively for 3 months and beyond, until the occlusion matures.
There is usually symptomatic improvement during this interval through development of collateral circulation.
It can then be dealt with by PTA or subintimal angio- plasty, when the thrombus will be sufficiently hardened and therefore be amenable to balloon dilatation.
If the limb warrants treatment sooner rather than later, then thrombolysis can be started, using the lytic agent recombinant tissue plasminogen activator (rtPA).
A suitable catheter is embedded into the thrombus and the lytic agent infused over several hours, with check angiograms performed at intervals to assess progress.
The underlying stenosis will be revealed and balloon dilated, to achieve a satisfactory haemodynamic result.
Thrombolysis can be used in conjunction with percutaneous aspiration thrombectomy (PAT) using a large-bore catheter.
Thrombolysis is most effective when the thrombus load is not too large.
Haemorrhagic complications are not uncommon, with a 1, 3% stroke and up to 5% death risk.
CONCLUSION PVD causes ulceration and gangrene in a substantial proportion of diabetic patients.
In view of the aging population and increasing incidence of diabetes, it is likely to present as a sub- stantial problem for vascular surgery/radiology departments.
Fortunately, with the availability of refined and varied guidewires, low-profile coated balloons and the availability of newer and minimally invasive techniques such as subintimal angioplasty, it is possible to treat the majority of patients.
In our unit the proportion of patients with critical limb ischaemia treated
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248 INTERVENTIONAL RADIOLOGY IN THE DIABETIC FOOT
by angioplasty was 23% between 1988 and 1991,29 46% in 199440 and 64% in 1997.32 Indeed, angioplasty has become the first-line treatment for the management of critical limb ischaemia, and with increasing experience, we believe that more than 75% of the patients with critical limb ischaemia can be treated in this minimally invasive fashion.