An Extreme Approach to CTOs via Retrograde Puncture of the Pedal Loop and Digital Arteries

What are the indications for use of a retrograde puncture of the pedal loop and digital arteries?

It is an extreme technique, so certainly after antegrade failure. This is a bailout technique, especially in patients who belong to the worse class, Rutherford class VI and University of Texas Wound Classification System 2D and 3D, meaning both infection and an ischemic situation together. Retrograde puncture can be used when it is not possible to recanalize a tibial vessel to the foot and when main arteries in the foot are not available, like the pedal artery or the plantar arteries, but some flow exists in some digital arteries or in the arch. It is possible to perform a puncture directly in those small arteries. In most cases, through retrograde recanalization, it is possible to recanalize the tibial vessel. 

Can you describe the technique?

Preparation of the patient is very important. We perform local anesthesia in the area where we want to stick the artery with a mixture of lidocaine and nitrate or any other vessel dilator. We also perform direct injection of dilators as well, via a groin injection, or even better, with a catheter below the knee, in order to avoid spasm. When you touch these tiny vessels with the needle, they can immediately spasm. Spasm is the first enemy in this case. We use a micropuncture introducer set from Cook. There is a set with a 21-gauge dedicated needle that is very short and stable. A short tip is important, because often the vessel is smaller than the tip of the needle. It is very important to use dedicated needles. We insert an .018” wire directly through the needle, either a dedicated wire from the micropuncture set or a V-18 Control Wire (Boston Scientific), which is a long wire that permits arrival at the origin of the vessel below the knee. When the support wire is in the vessel, we then insert the Cook microsheath that is sized as a 4 French sheath outside and 2.9 French inside. The microsheath has a lateral valve, making it possible to inject contrast medium or drugs. Through the sheath, it is possible to change wires, insert the support catheter (we use the CXI catheter from Cook) or directly balloon, if required, by changing out to an .014” wire and then inserting an .014” balloon. After retrieving the wire from below, the procedure continues from the antegrade approach. It is possible to see the puncture with a very small 1.5mm balloon inflated at nominal pressure for 3 or 4 minutes. We perform angioplasty in the digital artery and use it to seal the access without any problems.

Your center has a significant experience with retrograde puncture in these smaller arteries. How many patients have you done so far?

At this point, 45 patients. 

What can you tell us about outcomes?

We are going to publish, I hope in the very near future, the clinical result in this patient population. But I can say that we have realized that we can change the destiny of these patients. All were scheduled for a major below-the-knee amputation and we succeeded in performing a transmetatarsal amputation instead. We have been able to save their walking capability.

How would you describe the learning curve?

Experience with retrograde pedal artery puncture or posterial tibial puncture makes it easier, but I would say that after 5 or 6 patients, it is possible to perform this approach in the correct way.

What type of problems have you experienced?

The problem with this kind of approach also exists with all retrograde distal approaches — the amount of x-ray exposure, which is higher than with a common antegrade procedure. We really do not know how much more, however. It needs to be studied further in order to assess the real danger. 

How long does it take to gain access?

It depends, because the very first procedures, of course, were longer than the later ones. Sometimes you need only a few seconds to successfully perform the access. Of course, when the wire is in, the operator can stay far away from the beam, and the procedure is the same as an antegrade procedure. However, if you have difficulty sticking the artery, your hands are very close to the principal beam. One idea might be to modify the approach by using an extensor for the needle, allowing the operator to stay further away from the principal beam of the x-ray equipment. A company called Upstream in Israel is producing this type of extensor. It is not easy to obtain since there is no distributor in Italy, but we have found the needle extensor to be useful in reducing the x-ray exposure to the operator.

Dr. Marco Manzi may be contacted at marcodocmanzi@gmail.com.