|Year : 2015 | Volume
| Issue : 1 | Page : 18-20
How to Deal with CTO: Subintimal Angioplasty
Department of Radiology, Leicester Royal Infirmary, Leicester, United Kingdom
|Date of Web Publication||5-Mar-2015|
Dr. Amman Bolia
Department of Radiology, Leicester Royal Infirmary, Leicester
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bolia A. How to Deal with CTO: Subintimal Angioplasty. Indian J Vasc Endovasc Surg 2015;2:18-20
The conventional teaching has always been to cross an occlusion intraluminally. However with time the occlusions get harder and if the occlusion is long, it is unlikely that one would be able to keep the wire/catheter within the lumen. Furthermore, with an intraluminal angioplasty it is not difficult to see how, having displaced the atheroma and the occluding material in a concentric fashion, the recurrence rates would be high.
Our first case of subintimal angioplasty (SIA) 1987 resulted accidentally when a patient with claudication presented with a 10 cm occlusion of the popliteal artery. Dissection ensued and was pursued, and following balloon dilatation, good flow was achieved. A beautiful cosmetic result was seen 3 months later when the patient came to have his procedure done on the other leg.
With SIA, an occlusion is approached eccentrically, away from any important collaterals. The dissection space is entered with a catheter/wire combination. Soon after the catheter enters the occlusion a hydrophilic wire is manipulated to form a loop, which is then advanced through the length of the occlusion. In the vast majority of cases, the loop pops back into the lumen distally, and with balloon dilatation, a beautiful disease free channel is obtained within the subintimal space. A number of examples are shown with dissection clearly demonstrated.
The majority of the treatments can be carried out with the minimum of materials. A one part needle, Teflon coated and a hydrophilic guidewire, a simple curved tipped Mini-Cath, a balloon catheter and a simple inflation device is all that is required for the majority of the cases.
Most patients are on 75-150 mg of aspirin. 3-5000 international units of heparin are given prior to crossing a lesion. Vasodilators are only used when spasm occurs, or when dealing with small vessels in the infrapopliteal segment.
The advantages of the subintimal approach are two-fold: (1) Extended scope of treatment and (2) extended long term patency.
Flush and full length occlusions of the superficial femoral artery (SFA) can now be dealt with using this technique. The biggest challenge arises from making a correct puncture. The puncture must not be too high or too low, as the former may result in retroperitoneal bleeding, and the latter may cause difficulties in entering the flush occlusion.
There have been a number of publications, and while the numbers are small and there is a mixture of critical limb ischemia and intermittent claudication in most of the publications, it has however been shown that primary success rates are high ranging from 80% to 90% and the 1-year patency rates extending up to around 70%. However, these results can be significantly improved when the patients are put in a surveillance program and hence that when a stenosis is picked up, before the vessel becomes reoccluded, it can be angioplastied thus improving secondary patencies.
For critical limb ischemia there is no doubt that the subintimal approach makes a substantial impact, resulting in limb salvage rates of nearly 90% at 1-year.
The power of remodeling is rather under estimated. SIA produces good cosmetic results primarily but even better results subsequently where, with the effect of remodeling, the vessel diameter improves, and the dissection flaps smooth out with a healing process and also a number of branch vessels appear from the recanalized segment.
Stents are only used when there is significant recoil following balloon dilatation. Stenting in such a situation prevents the need for emergency bypass surgery.
In critical limb ischemia, where the predominant disease is in the tibial vessels, long tibial occlusions can be treated, multiple vessels can be recanalized and bifurcations and trifurcations can be reconstituted. A number of examples are shown of this phenomenon.
Two large systematic reviews by Met R and Bown have shown that the technical success rates tends to be high and limb salvage rates approaching from 80% to 90%.
Subintimal angioplasty is a relatively simple technique requiring the minimal of materials and therefore inexpensive. Good results and low complication rates have been shown. The treatment extends the scope of lesions that can be treated and it makes a major impact on the treatment of critical limb ischemia.
We only need a simple catheter and wire to perform the majority of cases of Peripheral Vascular Disease (PVD): This is a point of reflection in the sea of newer devices for treating PVD.
Plain old balloon angioplasty and SIA show high primary success rates of recanalization. However, when it comes to durability one has to aim for the best hemodynamics in order to achieve the best results. This usually means correcting any flow limiting situations, and providing as many run off vessels as possible, (more run-off vessels = better patency).
A survey of the last 100 subintimal angioplasties for femoropopliteal occlusions, which included 2/3 of the patients having critical limb ischemia and 1/3 of the patients having claudication, primary success rate of 90% was achieved for a mean length of occlusion of 22 cm. Primary failure was 10%, with a mean length of occlusion of 30 cm. When the 10 failures were analyzed, 7 were due to perforations of which 5 had very heavy calcification with a mean length of occlusion of 34 cm. Two occlusions were not calcified, 1 was 40 cm long and 1 was 5 cm long. The other 3 occlusions were "acute." One was a 60 cm occlusion, which was crossed but no flow was achieved. Second one was 10 cm long, but there was heavy underlying calcification therefore the thrombus could not be aspirated. A further 50 cm occlusion was aspirated but there was an underlying popliteal aneurysm.
This small study demonstrated that re-entry following a subintimal dissection, is almost certain to be achieved if there is minimal or no calcification in the vessels. If there is heavy calcification, perforation is likely. The failed calcified lesions were long in length (mean 34 cm). Failure is guaranteed when the occlusion is acute, especially if the vessel is calcified, as in these situations it is difficult to aspirate the fresh clot.
The main conclusion from this small study was that there were no failures due to lack of re-entry from a subintimal dissection.
For infrapopliteal occlusions, multiple vessels can be recanalized and there are 3 main reasons for doing so: (a) There is improved total perfusion to the foot, (b) There is better SFA patency with a three vessel run off and (c) there is insurance against blockage so if one vessel re-occludes, there would still be two remaining.
For tibial occlusive disease, the most useful wire is the 1.5 mm J hydrophilic wire in a 0.035 size and a support catheter using 5 French, 3 mm diameter and 2 cm long balloon catheter. Such device allows most occlusions to be crossed, at least up to the ankle level. Beyond this level smaller systems may be necessary.
Most publications have demonstrated that for critical limb ischemia high limb salvage rates of up to nearly 90% are achievable at 1-year. This result has also been reflected in large systematic review/meta-analysis where up to 90% limb salvage rates have been shown.
Iliac occlusions are probably the most difficult lesions to treat endovascularly. This is because during a retrograde approach to a common iliac occlusion the wire/catheter combination has a tendency to enter into a dissection but then subsequently quite difficult to re-enter back at the aortic level. This is not surprising as the intima at the aortic level is quite thick. Therefore, in such situations a re-entry device, for example Outback (Cordis) may become necessary. However we have found that for common iliac and external iliac occlusions the cross-over approach enables re-entry to be achieved distally without the need of a re-entry device.
The power of remodeling is demonstrated using a couple of examples.
An advantage of an endovascular approach is the possibility of treating a patient's inflow and outflow problem at the same sitting. For example if a patient has an External Iliac occlusion and a full length SFA occlusion, both these lesions can be treated by the cross-over approach using one puncture.
In conclusion, the majority of the occlusions can be crossed without any aids. Better case selection can improve the results further, particularly if heavy calcification and acute occlusions are excluded. One has to aim to achieve good hemodynamics in order to aid patency. Re-entry devices are most useful in common iliac occlusions. Stents, including covered stents are only useful for bail out.
Subintimal versus Intraluminal Angioplasty for Lower Limb Critical Limb Ischemia
Subintimal and intraluminal angioplasties for infrapoliteal occlusions are complimentary and not competing.
Critical limb ischemia is generally a disease of the tibial vessels. Therefore to treat critical ischemia means to be deal with tibial occlusive disease. The aim of this treatment is to establish good flow to the foot, with good hemodynamics. Long-term patency is not the goal. Subintimal and Intraluminal Angioplasty can achieve this goal. The difference between the two approaches, Subintimal versus Intraluminal, is that indications are different. Therefore for best results, one has to arm oneself with both techniques. SIA is applicable when there is not too much calcification, when the occlusion are long, when the bifurcation or the trifurcation needs to be reconstituted, and where there is a good target vessel (in this regard SIA can be lightened to a bypass procedure for which a good target vessel is also necessary).
The materials necessary are 0.035/1.5 mm J hydrophilic guidewire, a 3 mm × 2 cm balloon catheter on a 5 French shaft and a vasodilator (Tolazoline). The finer points for the technique are that one has to keep the loop short in order to avoid perforation. The 0.035/5 French system is useful when dealing with long occlusions, as this combination allows the system to be stiffened, with the use of a Half-Stiff or Stiff wire. A 1.5 mm J hydrophilic wire is a necessity for the procedure.
The advantage of the subintimal approach is that the bifurcation and the trifurcation can be reconstituted, long occlusions can be tackled and multiple vessels reconstituted.
The indications for intraluminal angioplasty are diffuse disease or a long stenosis, small vessels, cylindrical calcification (Renal failure and diabetic patients) and small diffuse target vessels (diabetics with no collaterals). A number of examples are shown of treatment of long occlusions, reconstitution of the bifurcation/trifurcation, and patients with diffusely diseased target vessels.
The main advantages of multiple vessel recanalization in patients with critical limb ischemia are: (a) Improved total foot perfusion, (b) better SFA patency with a 3 vessel run off and (c) Insurance against future blockage. A small number of publications dealing exclusively with infrapopliteal SIA has shown a high primary success rate of over 80% and once again, limb salvage rates rising from 80% to 94%.
| Conclusion|| |
Subintimal and Intraluminl Angioplasties are complimentary. Indications are different. Limb salvage rates are similar. One has to arm oneself with both techniques to achieve the best result.