New for 2022, I want to spend some time every Tuesday sharing with my readers a technical tip that I’ve learned which has helped me in my career. Selfishly, I’d like to use this opportunity as well to have you all share your tips with me so we can all learn from each other.
I want to spend today talking about limb salvage. And no, I’m going to spare you the emotionally charged rants about my feelings towards academic IR, even though I hope you do find those entertaining.
Instead, I want to talk about truly saving a leg. I think as IRs, we have a unique advantage when it comes to other endovascular specialists in that working in small vessels is something that comes relatively naturally to us. This is perfect for advanced limb salvage work because it undoubtedly requires dealing with below knee and oftentimes below ankle disease. Many old school physicians will say that there is “no use intervening on tibials” because doing so “isn’t durable.” Anyone who has committed themselves to stopping the proverbial chop knows that this is a bunch of crap and that going below the knee is vital to getting the job done, particularly for diabetics and renal disease patients who are disproportionately affected by distal disease as opposed to smokers who present with proximal disease.
So my tip for you today, be an expert angiographer first. We are truly useless without pictures. Here is how you obtain good pictures.
First, read this article from Radiographics: https://pubs.rsna.org/doi/10.1148/rg.316115511
Here you will learn how to obtain proper AP and lateral shots of the foot. Before that even, you need to start from the beginning.
- Access
Your access will be determined by your clinical exam. The vast majority of times, you will want to obtain ipsilateral antegrade common femoral or proximal SFA access to give you pushability to intervene on distal lesions. If you are going to go contralateral (usually hostile groins), then you are going to want to take a 90 cm or longer angled catheter and park it in the distal popliteal artery in order to obtain good images of the foot. If using CO2, then put a couple towels under the foot to raise it up.
Pro tip: Do not let the presence of a palpable pedal pulse keep you from taking the patient to angiography, especially if you have evidence of reduced toe pressure and the presence of a non-heaing wound. Certainly possible to have incomplete pedal loops or dorsalis pedis/lateral plantar disease occlusions. In ESRD patients, the lateral plantar tends to go first, followed by the dorsalis pedis.
- Getting Good Pictures
Contrary to popular belief, the AP foot shot is the most important shot. It gives you the most information necessary to assess distal perfusion and provides the optimal roadmap for completing pedal loops. To obtain this image you will want to angle the image intensifier parallel with the foot and make sure you can see the webspace between the first and second digits. A lateral foot shot will be merely 90 degrees to this angulation.
- Keep your patient comfortable.
Any minor motion will kill your image. Sedation and tending to patient comfort is key. If movement becomes a problem, tie both feet together. A quick note on sedation-understand that these patient are sick. Disease in their feet usually means disease in their coronaries. Sedation could kill a patient if they have one of four conditions: 3 vessel CAD, severe aortic stenosis, severe pulmonary hypertension or a low ejection fraction. Go low, go slow.
That’s all I have for today. Focus on obtaining great pictures to better understand anatomy and patterns of PAD. A foot shot is always essential. Don’t forget it.