It is natural to focus on the positive aspects of transpedal access and its value in infrainguinal revascularisation. However, we should not shy away from considering the limitations of this approach in order to obtain the best results for our patients, writes Jihad A Mustapha.
Limitations can be attributed to the following four major points:
- Not all all tibiopedal vessels are free of disease.
- Not all tibiopedal vessels have expected diameters; they all vary in size.
- Most diseased tibiopedal vessels have moderate to severe calcification in both the medial wall and intimal lining.
- Many advanced critical limb ischaemia patients have a single tibial vessel runoff.
When the above characteristics of tibial pedal vessels are taken into account, one can quickly be reminded that tibiopedal access sites are not meant to accommodate large bore sheath diameters for many reasons. Most importantly, the medial calcification of these vessels makes them vulnerable to longitudinal and circumferential fractures, which can lead to abrupt closure, spiral dissections and pseudoanuerysms, when a large bore sheath is placed in them.
What is a large bore sheath? The answer can be controversial depending upon which part of the country, or even world, you practice in. My group’s experience, so far, after using over 600 retrograde tibiopedal access sheaths has been overwhelmingly positive. Complications are much more likely to occur when the sheath size used is 5F or greater in diameter. When examining our past use of the 6F diameter sheath, we identified a higher incidence of complications including slow flow, pseudoanuerysms, and the need for additional balloon angioplasty due to persistent bleeding. These findings quickly drew our attention to the limitations of tibiopedal access for infrainguinal revascularisation.
Based on our experience in treating a large number of patients and the vast differences in the tibial vessel wall and lumen composition, I feel any sheath larger than 4F is considered a “large bore sheath” for the tibial pedal arteries.
Large diameter interventional devices such as self-expanding stents, atherectomy devices, and large balloons advanced through the tibial vessels into the popliteal-tibial junction can injure the tibial anatomy leading to proximal tibial dissection, embolization, etc. This is another major limitation of tibiopedal revascularisation and should be taken into account when using these vessels for access and revascularisation. Tibial-popliteal junctions are not in straight line and do have variable angles of the tibial arterial take-off. The anterior tibial artery has the highest angle, the posterior tibial is second and the peroneal has the least angle. If you have options to get access in any tibial artery, it should be the posterior tibial artery just above the level of the medial malleolus.
Prolonged sheath placement in a tibial pedal access without recurrent flushing and increased anticoagulation activated time with an activated clotting time of over 200 seconds throughout the whole time the retrograde sheath is in place contributes to additional limitations of transpedal access.
Another limitation of retrograde access is utilisation of a single vessel run-off in patients with Rutherford classification 1–4 claudication. It is important to note, that in this type of patient, aggressive medical therapy should be instituted before attempting retrograde access in the last standing vessel. Extreme caution should be taken when limb salvage is not the primary objection of the therapy. The scenario is different when tibial access is used in a limb salvage scenario.
In conclusion, transpedal revascularisation interventions have added significant value to the success of infrainguinal revascularisation in complex disease. Increased safety and efficacy is seen in lower profile sheaths, up to 4F diameter. Complications increase as sheath size increases. Also, the type of retrograde devices introduced in and out of the vascular tree from transpedal access is associated with higher complication rates if those devices are bulkier. This access approach should be reserved as a last option.
JA Mustapha is director of Cardiovascular Catheterization Laboratories, Metro Health Hospital, Wyoming, USA. He is a consultant to Terumo, Cook Medical and Cardiovascular Systems