There are a number of important pre-procedural considerations. The patient needs to be able to lie flat and still for the procedure (possibly for a number of hours) and if they are unable to do this then anaesthetic support for sedation and possibly general anaesthetic may be required. Pre-procedural imaging and previous endovascular interventions must be carefully reviewed. Recent blood tests should be available, particularly renal function. Aspirin should be continued pre-procedure and has been shown to reduce the incidence of peri-procedural thromboembolic events. If the patient is on warfarin this should be stopped, aiming for an INR <1.5 before intervention is performed.

The principle of any vascular intervention is to first ensure that inflow is restored (i.e., the most proximal level of disease is treated), before considering more distal intervention. Whilst much emphasis is placed on the below-the-knee (BTK) disease in patients with diabetes it is important to remember this principle and ensure that proximal iliac or femoral disease is adequately treated. It is also important to relate the severity of the clinical presentation to the planned endovascular treatment. For example, patients with intermittent claudication and combined SFA and BTK disease may derive sufficient benefit from treatment of the SFA disease alone, whereas patients with tissue loss usually require multi-level intervention.

A relatively recent concept is that of angiosome treatment, which has particular relevance to treating diabetic ulceration. The foot is divided into distinct vascular territories or angiosomes, one each from the anterior tibial (AT) and peroneal arteries (PA) and three from the posterior tibial (PT) artery. The AT supplies the dorsal side of the foot and toes, the PA supplies the lateral ankle and lateral heel, and the PT perfuses the plantar surface of the foot and the medial heel. There are small collateral vessels in the foot known as choke vessels, which are often compromised in diabetic patients. Studies have suggested that restoration of direct perfusion of the affected part of the foot, based on the angiosome concept, results in improved ulcer healing. Angiosome-targeted perfusion may not be possible due to severe disease of the target vessel. Some operators propose that, if possible, multiple vessels should be re-canalised. This technique improves total foot perfusion, and provides some insurance against subsequent blockage. We would initially try to treat the target angiosome vessel supplying the area of the foot with the ulcer or wound, but if this was not possible then we would attempt to restore flow in other vessels.

We use ultrasound guidance for all arterial punctures, as this reduces access site complications. The access route depends on the planned site of intervention. Antegrade access indicates the sheath is pointing in the direction of arterial flow, and retrograde access against the arterial flow. Antegrade common femoral artery access is usually employed for infra-inguinal disease, because the straight-line approach allows more “pushability” when trying to cross lesions and is preferable when performing a very distal intervention. Antegrade access may not be possible in obese patients or those with heavily scarred groins.

Retrograde common femoral artery access and an ‘up and over’ approach enable simultaneous assessment and treatment of iliac disease, and is appropriate for treating common femoral artery (CFA) or proximal SFA disease. A contralateral approach requires longer guide-wires, catheters and balloons, and monorail systems may prove useful. A contralateral approach may not be successful in patients with very tortuous or angulated iliac arteries.

Retrograde popliteal or below knee vessel access is becoming increasingly common for the treatment of more complex cases. Dedicated micro-puncture systems and pedal access sheaths are available for such cases.

The first stage of endovascular recanalisation is crossing the lesion. This can be achieved either intra-luminally or in the sub-intimal plane. There has been much debate over which type is preferential, but in practice, the type of lesion usually dictates the crossing technique. Stenoses are usually crossed intra-luminally and longer occlusions typically require a sub-intimal approach

To create a sub-intimal channel, a guide catheter is pointed towards the arterial wall at the proximal aspect of the occlusion and a hydrophilic guide-wire is passed into the space between the intima and media. The looped guide-wire is used to dissect a sub-intimal tract and then passed back into the true lumen at the distal end of the occlusion. Angioplasty then displaces the atheromatous and calcified intimal and medial layers to the contralateral side of the lumen, thus creating a neo-lumen. Care should be taken not to extend the created sub-intimal tract too distally, so as to preserve collaterals as well as possible distal targets for bypass. Re-entry into the true lumen may not be possible, particularly in extensively calcified vessels (reported up to 10–15 % of cases). Specialised re-entry devices are available such as the Outback^® (Cordis) and Offroad^® (Boston Scientific, Natick, MA, USA) devices. The Outback device is a 6F compatible catheter with a sharp, hollow 22G needle that can be directed towards and used to puncture back into the true lumen.