More Americans are living longer, and many develop multiple co-morbidities that preclude them from undergoing open surgeries. This has led to an explosion of endovascular treatments for cardiovascular disease. During the last decade, millions of patients with peripheral arterial disease (PAD) have benefited from these newer percutaneous approaches to treatment, including those with critical limb ischemia (CLI).
While open surgery still plays a vital role in limb salvage, a burgeoning variety of innovative endovascular techniques are proving to be quite successful in restoring blood flow for the most critically ill—and saving limbs.
What's Best For Whom?
“Open surgery in limb salvage is well established, and endovascular techniques are increasingly used. Both approaches have their clear indications. However, in some instances, both ways are acceptable, and that's what we need to clarify,” says Tareq Massimi, MD, vascular surgeon at MedStar Washington Hospital Center.
This is the goal of the international BEST-CLI study now underway. MedStar Washington Hospital Center and several other MedStar facilities are part of the multicenter U.S. arm of the investigation comparing optimal endovascular therapy to optimal surgical therapy in patients with CLI who are eligible for either approach. The study began in 2016 and will enroll more than 2,000 patients nationwide.
“To qualify for the study, patients must have advanced disease—CLI with rest pain or tissue loss (ulcer or gangrene),” Dr. Massimi explains. “After a thorough evaluation, if we determine the patient could benefit from either intervention and they agree to participate, they are randomized and receive the best possible approach of their assigned treatment.”
Throughout MHVI, 14 patients have been enrolled and are undergoing treatment. Dr. Massimi says, “We provide close, long-term follow-up to document complications, define which procedure provides the longest period of relief before the patient requires another intervention, and ultimately what produces the best outcome.”
Dr. Massimi says the study also may help eliminate institutional biases that are common nationwide.
“Everyone advocates for their own techniques—those they were taught during their training," he says. "Surgeons and interventionalists have their preferences, based on experience and historical data. This trial would clarify the right thing for the patient based on the outcomes.”
The BEST-CLI study goals also include building a “multidisciplinary structure that fosters cooperation among interventional cardiologists, interventional radiologists, vascular surgeons and vascular medicine specialists,” Dr. Massimi says.
Suzanne Kool, MD, a vascular surgeon in the Baltimore region of MedStar Heart & Vascular Institute (MHVI), says in her fellowship at Ohio State University she was involved in the BEST-CLI study and agrees that the goals of the study promote collaboration among vascular specialists. “In our practice in Baltimore,” she says, “we also include specialists in podiatry, diabetes, and plastic surgery. We are looking at bringing in everyone who can help treat the whole person and restore their quality of life as much as possible.”
Risk vs. Benefit
Dr. Kool says that just like other disciplines, as the technology has improved, so have the procedures. In her practice, she says, about 60 percent of her limb salvage surgeries are performed endovascularly. “Fifteen or 20 years ago, a shorter lesion would get a bypass. Those lesions are now being treated using endovascular techniques. These newer techniques are being used in more and more complex cases. But we need to be careful. Just because we CAN do a surgery endovascularly, SHOULD we?”
The advantages of endovascular procedures, she says, are:
- less risk of complications
- most are done without general anesthesia and are outpatient
- most have low blood loss, are less painful and have no long incisions that need to heal
A disadvantage, however, is that the benefits of endovascular procedures don’t typically last as long as those from open surgeries. “But longer term results may not always be needed,” she says. “For someone who is otherwise healthy and has severe disease, and you want the intervention to last long, then open is probably the way to go. But if you’re just hoping to improve flow long enough to heal a wound, then an endovascular procedure may be safer for someone who has comorbidities.”
It all comes down to what‘s best for the patient. Dr. Kool says, “We look at all the factors—age, comorbidities, and overall function status. For a bedridden patient who will never walk again, amputation can be the quickest and safest option to heal a wound without quality of life being affected. But for someone who could walk again, we aim to save the limb. If that’s not possible, the goal is to get them back to their baseline functionality. There is clearly still a need for both open and endovascular options.”
Growing Endovascular Arsenal
Today, numerous percutaneous approaches are being used to revascularize limbs in cases of CLI—with more in the pipeline. With CLI affecting about 1.4 million people in the United States and nearly 320,000 new cases every year, more widespread and targeted use of these techniques will no doubt save both limbs and lives.
“Which procedure we choose depends on the individual patient, the location of the obstruction, and the direction of the blood flow,” says Dr. Massimi.
“Using endovascular techniques, we are employing balloon angioplasty, drug-coated balloons, stents, and atherectomy devices to open and debulk plaques and various blockages, and treat de novo or restenotic lesions, all of which helps restore the blood flow into the limb,” he says. New and creative techniques also include retrograde pedal access for limb salvage in high-risk patients.
One trial at MHVI is looking at the variety of medications and doses for drug-coated balloons to determine what is most effective. Another trial is examining the use of shock waves to break up highly calcified plaques.
The well-established open bypass surgery also is performed with great results using natural grafts as well as synthetic materials bonded with heparin, Dr. Massimi says. “However, it will be a few more years until we know which is best for what patient.”
LimFlow: Veins Into Arteries
Nelson Bernardo, MD, medical director for Peripheral Vascular Intervention at MHVI and director for Peripheral Interventional Research Studies at MedStar Cardiovascular Research Network, is leading a feasibility study of an investigational revascularization technique called LimFlow™.
The LimFlow System is currently indicated as a treatment for patients with end-stage CLI who have no other revascularization option—and have failed either endovascular or surgical interventions, or even both. “The procedure is based on a concept devised some time ago for use in the heart to ‘bypass’ occluded coronary arteries,” says Dr. Bernardo.
The LimFlow procedure entails the creation of a fistula from an artery in the leg to its accompanying vein. The latter carries the oxygenated blood flow into the critically ischemic foot via venous pedal arch acting as the arterial system. The vein is accessed distally at the level of the ankle while the artery is accessed at the groin area using the antegrade femoral approach. Catheters are advanced from both access points, and these meet at an area above the arterial obstruction. A connection is made across from the patent segment of the artery to the vein, guided by the LimFlow ultrasound system.
To ensure correct direction of blood flow distally to the foot, “push valvulotome” is used to disrupt the venous valves. This is followed by the implantation of LimFlow ePTFE-covered nitinol self-expanding stents from the arteriovenous crossing point down to the ankle. This ensures laminar flow through the arterialized vein and into the pedal arch to perfuse the ischemic foot.
“Disappointing results in the heart led to its adaptation and use in the vascular bed of the legs. MedStar Washington Hospital Center is one of the few U.S. centers conducting the FDA-approved feasibility study,” Dr. Bernardo explains.
“The goals of this pilot study are to investigate the safety, effectiveness and feasibility of the LimFlow procedure for the treatment of critical limb ischemia. We have treated five patients thus far, individuals who have been designated to have no hope, with no discernible blood flow to their foot. Limb loss/amputation is typically inevitable for these patients who present with complaints of resting foot pain, non-healing wounds/ulcers, and even gangrene.”
“Wound healing is critical to the success of this procedure and all treatment for CLI,” says Dr. Bernardo. “We have an entire expert team led by podiatric surgeon John S. Steinberg, DPM, and plastic surgeon Christopher Attinger, MD, who help ensure optimal recovery.”
Dr. Bernardo says, “LimFlow is a simple but ingenious approach that shows great promise. Patients I’ve performed the procedure on feel relief from pain. What is very dramatic is the immediate relief of resting ischemic pain. At the end of the procedure, one is able to touch the affected limb without any complaint from the patient.
“It’s one of a number of endovascular techniques with the potential to reduce amputation and agonizing pain in patients with CLI—and dramatically improve quality of life.”