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Access in CLI: Should CLI Centers Still Practice Access Without Ultrasound?
In this issue, we are privileged to have two busy critical limb ischemia (CLI) specialists, Dr. George Adams and Dr. Fadi Saab, discuss the controversial topic of imposing ultrasound for access in all arterial conduits during CLI therapy. This forum is intended to open the discussion of why some operators continue to use palpation and angiographic access, and why some have shifted exclusively to ultrasound-guided access. We will hear supporting scientific evidence behind each type of approach, and the pros and cons of each.
George Adams, MD, is an interventional cardiologist at Rex Hospital and the University of North Carolina Health Systems in Raleigh, North Carolina. He is the Director of Cardiovascular and Peripheral Vascular Research. Dr. Adams is a seasoned and well-versed CLI endovascular therapist with excellent outcomes.
J.A. Mustapha, MD: Dr. Adams, how many peripheral vascular endovascular procedures do you perform yearly?
George Adams, MD: I perform 900-1,000 peripheral vascular interventions per year.
Dr. Mustapha: How would you describe the trajectory of your skillset in CLI therapy? Is there a point where your skills have leveled off or do you anticipate a continued rise in your skill level?
Dr. Adams: The CLI population is increasing, especially with the growing epidemics of diabetes, renal insufficiency, and an aging population. For the majority of these patients, I am the last option before amputation. As such, developing novel techniques and devices for access, crossing, and treatment are instrumental in restoring blood flow to salvage limbs. With these new techniques and devices, yes, my skills continue to evolve, and I do not see any time in the near future where they will level off.
Dr. Mustapha: You report that you do not use ultrasound guidance in your daily practice. I have observed you during live cases and have seen how well you do getting access into target conduits without ultrasound. Please elaborate on how you achieve this level of success in all different arterial conduits?
Dr. Adams: Understanding the anatomy and angiographic views, as well as using devices that decrease complications, are instrumental in gaining safe, reliable and predictable access. For example, I access all arterial conduits (radial, brachial, femoral, popliteal, tibial, and digital) with the same equipment. I use a 21-gauge micropuncture needle and dilator on every access. In addition, I use a long, 80 cm, nitinol wire with a preformed tip (Nit-Vu, AngioDynamics) to prevent shearing of the wire and loss of wire in the body. It also it provides good tactile sensation. Peroneal access is a great example of the importance of anatomy and angiographic views. This artery lies deep in the lower leg behind the interosseous membrane. As such, ultrasound is typically ineffective for those that use it. To gain access, the angiographic camera is rolled laterally (right lateral for the right leg and left lateral for the left leg) approximately 30-40 degrees until the fibula and tibia are splayed. Access by the operator is parallel to the beam of the camera (coming in at the same 30- to 40-degree angle) and perpendicular to the vessel (Figures 1-2). Tactile sensation is important, because the operator will feel a “pop” on the needle passing through the interosseous membrane. The peroneal artery lies directly behind the membrane. To visualize the depth of the needle, the camera can be rolled 90 degrees medially.
Dr. Mustapha: What is your preferred access method for complex tibial-pedal disease?
Dr. Adams: For complex tibio-pedal disease, I always come from a contralateral retrograde or antegrade approach first. I typically use a .014-inch platform to cross, allowing my entire tool bench to be utilized.
Dr. Mustapha: What do you think about those centers that have shifted completely to ultrasound-guided access?
Dr. Adams: I applaud those centers that have switched completely to ultrasound-guided access. My hope is that radiation and complications may be reduced with this technology. However, realistically, the majority of centers around the world cannot partake in the expense of the equipment, ultrasound technician, and additional time and training to become proficient.
Dr. Mustapha: Is there a place for ultrasound-guided access in your practice?
Dr. Adams: I typically do not use ultrasound-guided access. I have become proficient with angiographic access and currently ultrasound-guided access is not warranted.
Dr. Mustapha: Does tibial access, with or without ultrasound, add value to CLI therapy?
Dr. Adams: For those clinicians who are versed in using ultrasound and/or cannot access with typical angiographic views and techniques, ultrasound is of the utmost importance.
Dr. Mustapha: Where do you stand in terms of the time to obtain tibial access?
Dr. Adams: Tibial access on average takes less than 5 minutes. I always try from above, first crossing with a 0.014-inch platform to leave my tool bench open. Time to access is lesion-dependent. I will spend more time crossing longer lesions (20-40 cm), but typically not longer than 10 minutes of fluoroscopy time for any lesion. I then will look for any transcollaterals and attempt access for a maximum of 5 minutes. If unsuccessful from both antegrade and transcollateral access, I will perform a retrograde access. Specific signs that would cause me to switch to a retrograde access would include not reentering the true lumen, the wire obviously extending in a plane farther from the reentry site, and when a large branch (such as the profunda) may be jeopardized from an antegrade approach.
Dr. Mustapha: What is your institution’s access complication rate for CLI cases?
Dr. Adams: Tibial access complications in our institution are less than 1%. The rare tibial access complication is likely related to anticoagulation, vessel size, and extended length of time working within the vessel.
Dr. Mustapha: What advice can you provide to the younger CLI therapist who is starting to dive into unpredictable and complex CLI revascularization cases?
Dr. Adams: The keys to success to developing a successful CLI program include:
- Patience. These cases are typically multilevel, chronic total occlusions and contain calcium. Therefore, many cases may extend 2-4 hours.
- Tools. “A carpenter is only as good as his tools.” Become versed in and understand how to personalize a variety of access, crossing, and treatment tools. This would include but not be limited to atherectomy, thrombectomy, devices with biologics, wires, and catheters.
- Skill. Develop safe, reliable, and predictable techniques to access, cross, and treat lesions. Remember, for many of these patients we are their last resort before amputation.
Fadi Saab, MD, is an interventional cardiologist who practices at Metro Health Hospital in Wyoming, Michigan. He is a very busy CLI specialist who opts to use ultrasound for access in all conduits, arterial and venous. His practice is the complete opposite of what we have just heard from Dr. Adams; yet he also has a high success rate and low complication rate.
Dr. Mustapha: Dr. Saab, Dr. Adams elaborated on the fact that he is able to get access in all arterial conduits without ultrasound. What are your thoughts?
Dr. Saab: The classical training of interventional cardiologists has revolved around palpation and fluoroscopic guidance. However, this approach has failed to succeed when it comes to alternative and tibial access in patients with advanced peripheral vascular disease (PVD) and critical limb ischemia (CLI). I switched my practice from fluoroscopy-guided access early on in my career simply because of the high failure rate of obtaining tibial access. Dr. Adams has highlighted the steps required to obtain fluoroscopic-guided tibial access above. I will leave it up to the reader to make a comparison and determine which approach is easier, attainable, and sustainable.
Dr. Mustapha: What caused you to make a complete shift to ultrasound-guided access so early in your career?
Dr. Saab: Early on, I learned the success of my procedures depends solely on my ability to obtain access. For example, when a CLI patient is referred for limb salvage, there are two clear outcomes. Either there is success in establishing in-line blood flow to the limb and saving the leg, or failure to achieve adequate revascularization and acceptance of the fateful outcome of amputation. With such responsibility, the clinician has an obligation to utilize any technology that affords him an advantage. A huge part of our institution’s amputation prevention program success is our ability to obtain access in tibial vessels using ultrasound guidance.
Dr. Mustapha: You are always advocating the importance of ultrasound. How can busy clinicians incorporate such tools in their practice?
Dr. Saab: I often hear physicians, regardless of their discipline, describing ultrasound as a nice skill to have, but not necessarily essential. Nonetheless, there is a huge demand throughout the country for physician education regarding the use of ultrasound in gaining access to arterial conduits, mainly tibial vessels. The Amputation Prevention Symposium (AMP) was the first congress to recognize the importance of educating healthcare providers regarding the importance of ultrasound. It is for that reason that a significant portion of the AMP program focuses on ultrasound. The meeting hosts hands-on ultrasound training where experienced faculty educate physician attendees on ultrasound mapping of the lower extremity arterial circulation. The training involves describing and identifying ultrasound landmarks where physicians can identify borders of multiple structures such as the common femoral artery (CFA), for example. In addition, physicians practice scanning tibial vessels of live models with healthy vessels, diseased vessels and abnormal anatomy. This exercise is essential, because it helps physicians learn important images they can recognize in their patients. For the cardiologists, it can be equated to reading an echocardiogram where the physician studies normal and abnormal variations of cardiac anatomy. This knowledge is important to replicate when it comes to peripheral arterial anatomy. Another important hands-on event held at AMP is the Ultrasound-Guided Tibio-Pedal Access Workshop utilizing human cadaveric models. A physician who completes this training course can become comfortable obtaining ultrasound-guided access in cadaveric models. The high success rate of this approach causes me to believe the skill set is attainable and sustainable. In these workshops, 100% of the physicians are successful in gaining ultrasound-guided tibial access. Having seen the results in the workshops at the AMP Symposium, our team has incorporated cadaver workshops in the physician training courses held at Metro Health Hospital.
Dr. Mustapha: Are all CLI cases and procedures defined equally as of today?
Dr. Saab: I believe the term “CLI” alone is vague. Not all cases are created equally. My response here focuses mainly on the anatomical considerations and complexities. For example, the Peripheral Registry of Endovascular Outcomes (PRIME) collects anatomical details regarding the pattern and distribution of disease. To date, the lesion lengths reported range in length from 5 to 500 cm. The average lesion length is 120 mm with 1.5 average lesions being treated in each procedure. Almost 50% of the CLI patients in the PRIME registry required a pre-planned, staged intervention for the same limb. Sixty percent of patients had combined suprapopliteal and infrapopliteal lesions, and 19.5% of patients have isolated infrapopliteal/tibial disease. These few highlights demonstrate the wide range of presentation for CLI patients. Unfortunately, randomized trials have failed to capture this level of complexity for obvious reasons. This is why real-world registries like PRIME are very important to show the true nature and difficulties in managing this complex population. Relying solely on the highly sub-selected group of CLI patients enrolled in randomized, controlled, clinical trials does not show the true nature of CLI as a whole and limits the support in treating CLI. Despite the earlier challenges described earlier, amputation prevention remains a cost-saving measure in comparison to leg amputation.
Dr. Mustapha: Can you explain the steps you take to obtain access in tibials, including what type of ultrasound probe you use?
Dr. Saab: The tibial vessels are accessed in the following fashion. Typically the foot is prepped and draped separately. The orientation of the foot is adjusted depending on the target tibial vessel. In cases of the dorsalis pedis (DP) or the distal anterior tibial artery (AT), the foot is maintained in natural orientation, with the heel of the foot on the mattress with slight dorsiflexion. To access the posterior tibial artery (PT), the foot is rotated laterally and the leg will be bent slightly at the knee level for patient comfort. To access the peroneal artery, the foot needs to be rotated further laterally to separate the fibula and tibia. This maneuver will facilitate direct cannulation of the artery. A vascular technologist is present during the access process. My group typically employs the Philips linear 15-7 MHz hockey stick-shaped probe and the Philips iU22 xMatrix ultrasound machine. Studying the tibial vessel is of particular importance. The short and long access views of these vessels will reveal the access point. The operator monitors the introduction of the access needle. The vessel is accessed in a cross-sectional fashion, then the probe is changed to longitudinal plane to watch the advancement of the wire (Figures 3, 4a and 4b) Once access is gained into the tibial vessel, the micro sheath is introduced.
Dr. Mustapha: What are your steps for CFA antegrade and retrograde access?
Dr. Saab: Antegrade and retrograde CFA access is typically handled by the operator. In cases of difficult access such as obese patients and fibrotic groins, the ultrasound technician may assist. In antegrade access, the CFA artery should be accessed 2-2.5 centimeters above the bifurcation. Studying the vessel will allow the operator to access the CFA, avoiding the external iliac. Accessing the external iliac is a costly mistake. The needle should enter the artery under direct visualization. The wire may be advanced. The ultrasound probe orientation can be changed from cross-sectional to longitudinal. Typically the wire is sub-selective into the profunda, generally related to the angle of entry into the skin and angle between the superficial femoral artery (SFA) and profunda. A sheath is then advanced into the CFA. At this stage, the access wire is maintained in the profunda and the dilator is removed. Another 0.018-inch wire will be introduced through the sheath. A bend is placed on the tip of the wire and guided under ultrasound into the SFA. Once the wire is advanced into the SFA, the access wire will be removed and the dilator of the sheath is introduced over the 0.018-inch wire. This approach advances the sheath into the SFA and secures the antegrade access.
During retrograde CFA ultrasound-guided access, the physician will interrogate the CFA in a short access view, and scan up and down to identify the SFA/profunda bifurcation. Needle access will be performed under ultrasound access and in certain cases, a long access view can visualize the wire through the needle.
Dr. Mustapha: Do you believe that ultrasound has improved your time to access?
Dr. Saab: Absolutely. The average time to obtain tibial access, currently reported in the PRIME registry, ranged from 41-59 seconds. The average number of attempts ranged from 1.2-1.4 times. No significant difference has been noted between CFA antegrade and retrograde access, in terms of time to access (45 vs 39 seconds). This is especially evident with emergencies. Our practice has incorporated the use of ultrasound-guided access to enter the radial and common femoral arteries when treating coronary emergencies, such as ST-elevated myocardial infarctions. Saving time to access is not the only advantage, but success in actually obtaining tibial access is significantly higher. Tibial access remains a challenge for a lot of clinicians. By incorporating direct visualization of the vessel, you avoid surrounding venous structures, and above all, the frustration of blind sticks. Finally, choosing an adequate arterial access point within the CFA where there is no significant plaque or calcification will pave the way for a safe exit strategy and allow the operator to use closure devices if needed.
Dr. Mustapha: What is your institution’s access complication rate for CLI cases?
Dr. Saab: Before I answer this question, we must recognize that becoming proficient in using ultrasound for access requires time. Based on our experience in proctoring physicians and training fellows, the time frame for proficiency ranges from 3-6 months. The variability depends on multiple factors. The most important is physician commitment and tenacity. Also, the type of equipment available for the physician plays an important role. For example, there is a big difference between a basic SonoSite machine and the more advanced arterial imaging ultrasound-devices like the Philips IE 22 when used in CLI cases. I continue to emphasize the importance of attending training courses and meetings focused on use of ultrasound. During training courses at Metro Health Hospital, the evening before the course is dedicated to the discussion of ultrasound, paired with a hands-on training session where the physicians scan live models with normal and abnormal anatomy, and learn to identify arterial structures, including tibiopedal vessels.
Dr. Mustapha: What is your most common access complication and what do you do to prevent it?
Dr. Saab: This may come as a surprise to a lot of providers, but we tend to have a significantly low number of complications with ultrasound-guided tibial access. We continue to see a higher rate of hematoma formation in patients with antegrade CFA access (1.5-2.1%). In cases where ultrasound was used adequately, we have not seen cases of retroperitoneal bleeding. We believe the success is related to incorporation of a few techniques. First, in patients with an ACT above 200, we usually consider reversing anticoagulation by giving a protamine-testing dose. I, myself, usually do not exceed a total of 25 mg to reverse anticoagulation. Another, newer approach has been the use of closure devices, in particular the Mynx Vascular Closure (Cardinal Health) and Perclose ProGlide (Abbott Vascular). When we use the Perclose closure device, we use the ultrasound probe to visualize the foot pedal of the closure device against the arterial wall. This confirms location and allows the device to be deployed safely.
Dr. Mustapha: Why do you think the ultrasound-guided access approach is superior to non-ultrasound guided access?
Dr. Saab: There are multiple reasons. First, most obviously, is direct visualization of the vascular structure. This is especially important in patients with PVD and impaired pulses. In patients requiring tibial access, there is no sense in using palpation maneuvers, because there is nothing to palpate. The second is radiation exposure. The times mentioned previously regarding time to access when using ultrasound are relatively short. To draw a comparison with fluoroscopy, one must consider the following: access must be obtained in one of the CFAs and adequate angiography with large contrast volume will be required to identify the tibial targets. After that, the operator must use fluoroscopic guidance, exposing his or her self directly to radiation in order to access the vessel. During this whole process, the patient may not move, venous access may occur, and any slight change in the foot orientation will lead to repeating the whole process. In addition, orthogonal views may be required to access the vessel correctly. These additional steps can double the time required, and increase radiation time and contrast volume.
Dr. Mustapha: What would you say to the new operator performing CLI therapy to convince them to use ultrasound for access?
Dr. Saab: One must recognize the skillset of experienced operators using fluoroscopy to gain access into arterial conduits. However, to reach that level of comfort, they had to spend endless hours of unnecessary contrast and radiation exposure to themselves and their patients. With that said, I truly believe that if they were afforded the current ultrasound technology or training, they would embrace the ultrasound approach. Any new CLI operator that is looking to increase success rate of revascularization and decrease complication rates must embrace and incorporate ultrasound into practice.
Dr. Mustapha: Do you predict a future where we continue to have friendly disagreement between believers and non-believers of ultrasound-guided access, or do you predict a future where one will prevail as the gold standard?
Dr. Saab: In my opinion, the verdict is already in. Ultrasound-guided arterial access is far superior to blind palpation/fluoroscopic modality. In the era of quality metrics and outcomes, I suspect that using ultrasound will become routine care in a fashion similar to using ultrasound to gain access into venous conduits. Institutions and providers will be assessed based on their ability to include this skill into their practice.
Dr. Mustapha: Tell us more about your intraprocedural ultrasound utilization and how this approach has impacted your outcomes?
Dr. Saab: The term described as extravascular revascularization (EVUS) refers to the use of transcutaneous ultrasound imaging to visualize vascular structures and equipment. The immediate and live feedback will allow the operator to adjust his treatment plan, depending on images provided. Non-invasive arterial duplex imaging uses real-time ultrasound to image vascular structures. This is the natural evolution of incorporating ultrasound into revascularization protocols. Once the physician becomes proficient in gaining access and assessing arterial structures, he or she will be able to use ultrasound to identify wires, catheters, and devices within the vessel. Furthermore, the physician will be able to guide the devices within the artery. EVUS can aid the physician in guiding therapy. Ultrasound is helpful in identifying crushed stents. I recall one case where the popliteal artery appeared aneurysmal under ultrasound. The patient was originally treated as a traditional SFA/popliteal occlusion. Angiography with fluoroscopy had clearly failed to identify the underlying thrombosed popliteal aneurysm. The patient was referred for a second opinion and during revascularization, the aneurysm was discovered and the treatment algorithm changed completely. These techniques are still in their infancies. I find that we are constantly evolving and attempting to increase our accuracy, decrease our radiation exposure, and improve our outcomes.
Disclosure: Dr. Mustapha reports he is a consultant for Bard, Covidien, Cordis, CSI, Spectranetics, Boston Scientific, Cook, and Terumo. Dr. Saab reports he is a consultant for Terumo, Cook, CSI, Covidien, Spectranetics, and Bard. Dr. Adams reports he is a consultant for Cook Medical, Daiichi Sankyo, Lake Region Medical, Volcano, Asahi, Abbott Vascular, CSI, Medtronic, and Terumo. He is a speaker for Abbott Vascular, CSI, Cook Medical, Medtronic, and Spectranetics. He has received research support from Boston Scientific, CloSys, Daiichi Sankyo, Flexible Stenting Solutions, Medtronic, Volcano, and Mercator.
Dr. J.A. Mustapha can be contacted at jihad.mustapha@metrogr.org.
Dr. George Adams can be contacted at george.adams@unchealth.unc.edu.
Dr. Fadi Saab can be contacted at fadi.saab@metrogr.org
