Strategies for Failed Antegrade Approach for Infrainguinal CTOs

J.A. Mustapha, MD:  Dr. Razavi, please describe the type of infrainguinal chronic total occlusions (CTOs) that cause you to say “this is going to be a very long case!”

Mahmood Razavi, MD:  As you are well aware, long occlusions of either anterior tibial (ATA) or posterior tibial (PTA) arteries feeding the ischemic location of interest in the foot can always be challenging and at times unpredictable, especially when densely calcified. This is due to the absence of optimized devices to deal with luminal or subintimal recanalization and reentry in such below-the-knee lesions. 

Having said that, long total occlusions involving the arterial segments that span across different named territories require a pre-procedural bladder check by everyone in the angio suite! Meaning, long CTOs that involve the trifurcation with reconstitution of the distal tibial arteries or proximal occlusions of ATA or PTA with reconstitution below the ankle.

Besides lesion length and involvement of the trifurcation, lesion characteristics such as dense calcification or long lesions in patients with thromboangiitis obliterans (Buerger’s disease) can often test one’s patience and commitment, especially in a busy day. 

Dr. Mustapha: What type of CTOs do you consider straightforward?

Dr. Razavi: I don’t think there is such a thing as a “straightforward CTO” in below-the-knee vessels, since even a short occlusion can pose a significant challenge at times. CTOs have a way of humbling even the most gifted of the operators, not that I come anywhere close to being one. Just a few weeks ago, I spent over an hour trying to recanalize what appeared to be a “straightforward” short CTO of a tibioperoneal trunk with favorable proximal cap configuration, but failed miserably. Eventually I had to resort to a retrograde access to cross the short lesion and reestablish flow. 

Generally, however, short CTOs with favorable cap configurations or lesions with a “string of lakes” appearance (multiple, short segment or focal occlusions/stenoses with focal intervening reconstituted segments) can be crossed with relative ease. 

I do want to emphasize, however, that crossing a lesion with a wire and treating it successfully are two different things. There are lesions that can be crossed relatively easily with a wire but that do not allow passage of a therapeutic device and/or that do not respond to one. 

Dr. Mustapha: In your daily practice, what is your most common access approach? Is it contralateral up-and-over, antegrade, or antegrade/retrograde?

Dr. Razavi: For claudicants, we generally access the contralateral groin. This allows interrogation of the iliac arteries (including the internal iliac arteries), and common femoral (CFA) as well as profunda femoris arteries. Treatment of the proximal superficial femoral artery (SFA) is also less problematic. The disadvantage is, of course, having to deal with possible tortuousity of the iliac arteries or the nuances of aortic bifurcation. 

For infra-popliteal interventions in patients with critical limb ischemia (CLI), however, I generally use the following protocol:

1) Contralateral CFA: Used in cases of hostile ipsilateral groin, poor body habitus (severe obesity), or presence of treatable proximal disease. The logic of this approach is fairly self-explanatory. 

2) Ipsilateral CFA or proximal SFA: Used in CLI patients who do not fall in the above groups. This is my preferred approach, since it improves pushability and torquability of wires/catheters, and enhances the overall ability to cross and treat tough lesions. Additionally, an ipsilateral access reduces the concern about the device delivery length should pedal or trans-collateral approaches become necessary (in which case, one may require balloon/stent shaft lengths longer than what is currently available in the market). 

3) Tibio-pedal access: This is a remarkably useful approach in cases of failure of antegrade access to cross a vessel. We use it as a backup access and it has become necessary in roughly 5% of the cases we see. Literature shows that when antegrade crossing fails, a retrograde attempt can be successful in about 90% of those cases. Hence, a retrograde access (pedal or popliteal) in our lab is almost always when the more traditional approaches fail. 

4) Radial access: Apart from the coronaries, this is better suited for mesenteric, renal, vertebral, and subclavian interventions rather than peripheral arterial disease (PAD). For us, this is a very rare approach for treatment of lower extremity arterial disease interventions, even for iliac arteries. I prefer to use CFA, SFA, popliteal, and or tibio-pedal access over the radial artery any day for this purpose. 
The reasons for my lack of enthusiasm to use radial access for PAD interventions include the loss of crossing ability of tough lesions (loss of torquability, pushability, maneuverability, and reach of devices); reduced ability to deal with potential complications such as vessel injury or thrombo-embolic events; having to deal with the nuances of the aortic arch; potential of stroke (albeit a very small risk); poorer angio room logistics (although probably better than pedal access); potential for loss of the radial artery, which is completely unnecessary for PAD interventions; and an inability to upsize the sheath to a 7 or 8 French should I need it. 

Dr. Mustapha: How far into a CTO procedure do you have to be before determining your approach is not working and it is time to switch to another method?  

Dr. Razavi: In the SFA where the use of reentry devices is more efficacious, my threshold for switching to such a device is bit lower. If unsuccessful, the common techniques I use include pulling back and re-tracking through a different path and the use of more angulated catheters, etc. I may give each step 5 minutes or so before moving on. Of course, if I see angiographic connection between the lumen I created and the reconstituted vessel, I may persist longer than 5 minuntes in trying different wires and catheters. If various attempts fail for about 15-20 minutes, then I consider the use of a reentry device or a retrograde approach like popliteal. This, of course, depends on the angle of the aortic bifurcation and iliac tortuousity, degree of difficulty to pass the reentry device through the CTO, and so forth.

In below-the-knee interventions, I prefer a retrograde access in case of failure, if there is a good target. I admit that my threshold to move to a second access is a bit higher. If my initial cath/wire fail to cross for about 5 minutes or so, I try changing wires/catheters and switching to specialty CTO devices. Use of sharp-angled catheters, balloon-assisted reentry, and trans-collateral recanalization are all common alternatives I use in a hierarchical manner. If these fail for about 30-40 minutes, then I secure a distal access for a retrograde approach. 

Dr. Mustapha: In a perfect world, if you could ask for the perfect CTO crossing device for CLI CTOs, how would you describe it?

Dr. Razavi: I am not much of a Star Trek fan, but would love to have a device that I can externally move over the CTO and recanalize it. If you think about it, that is not so far-fetched, given the state of technology in externally applied energy sources and image-guided therapies. In fact, the device can likely guide itself over a vessel and will not need a physician for operation, only for prescription! I probably just made this a busy intellectual property landscape.

While we are waiting for the invention of my externally applied system, a “perfect” CTO crossing device would have to have superior maneuverability with high fidelity to advance through dense, calcified or fibrotic lesions. It will have to have an imaging component to guide its advancement. Since we are thinking “perfect”, it should also be able to treat the lesion as it crosses to reduce time-wasting exchanges. This type of device will almost certainly change a “Razavathon” or “Mustaphathon” case into a “Razavimin” case, a far more enjoyable situation by all concerned, especially my technologists and nurses (a “Mustaphimin” case does not sound quite as good!). 

See Case Example below.

CASE EXAMPLE

Case by Mahmood Ravazi, MD

This is an 81-year-old female with a 5-week history of left heel ulceration. Her past medical history includes diabetes mellitus, hypertension, chronic kidney disease stage IV, and dyslipidemia. She is status post right above-knee amputation. Physical exam revealed palpable femoral pulses and no distal pulses in the left foot. Left ankle-brachial index (posterior tibial artery) was 0.36.

Disclosure: Dr. Mahmood Razavi reports relationships with the following companies over the past 12 months: Abbott Vascular, Zimmer Biomet, Boston Scientific, Cagent, CSI, Medtronic, MicroVention-Terumo, Penumbra, ReFlow Medical, Soundbite Medical Solutions, and Veniti. 

Dr. Mahmood Razavi can be contacted at mrazavi@razavimd.com.

Dr. J.A. Mustapha can be contacted at jmustapha@acvcenters.com.