New technologies are essential for improving infrainguinal therapy. This statement is based on the historic fact that the majority of devices and tools, tips, and tricks, have been borrowed from FDA-approved products and techniques that were used elsewhere in the body. It is nice to see that innovators have now begun to look more closely at infrainguinal disease, understand it, and build devices with specifications addressing the complexity of infrainguinal disease. In this issue, we will be sharing a unique spin on our discussion, with an innovator who is also an operator that invented a device during his struggle to resolve a resistive, complex lesion. The birth of this device was the direct result of the unmet need of the infrainguinal complex lesion. It is a pleasure for us to introduce readers to a device built specifically for infrainguinal disease, not borrowed from somewhere else in the body.
J.A. Mustapha, MD: John, it is not very often that we encounter a physician who faces difficulty during an attempt to treat complex lesions and who then goes on to develop the exact tool that is necessary to resolve the resistive lesion. Much less, a tool that leads to a high success rate in completing revascularization. Please walk us through the steps from inception of the concept to FDA approval.
John Pigott, MD: I have been a high-volume interventionalist treating critical limb ischemia (CLI) patients, and have used all of the devices on the market. My concept was to design a cost-effective plaque modification/vessel prep device, especially in the era of drug-coated balloons. I wanted something simple that did not need to be attached to a power source, and that was quick to use for efficient laboratory throughput. I had a number of ideas, but I relied on input from colleagues in the medicine industry, venture capitalist (VC) firms, and focus groups, and we settled on this one. I’ve learned a lot along the way. I definitely wanted the 510k process, rather than PMA [premarket approval]. I also found it extremely important to bring on a CEO experienced in medical device companies. Funding of the project is really a full-time job, and I have found it an interesting process to assemble through grants, VCs, and private equity funding. For a physician scientist, the tremendously rewarding part has been the opportunity to treat patients with the device that I conceived, and to see it come to fruition and improve patient care. From inception to FDA clearance, the process took approximately three and half years. It was very challenging but very rewarding at the same time.
Dr. Mustapha: It is an extensive process. Most of us as physicians, including me, do not realize how much effort it takes to get a device to market. I have a much higher appreciation for the extensive nature of this process. How has this device changed your practice personally?
Dr. Pigott: This device, the Flex Scoring Catheter (VentureMed Group), is currently cleared for use in the femoral popliteal as well as arteriovenous access. I am using the device in our clinical practice for both of these indications. I am currently doing less atherectomy and more Flex procedures. I am following each femoral popliteal Flex case with a drug-coated balloon. So my personal algorithm has changed from atherectomy or stenting, to Flex, followed by a drug-coated balloon.
Dr. Mustapha: What is the mechanism of action of this device that makes it unique and effective in complex infrainguinal disease?
Dr. Pigott: One characteristic that makes the Flex a unique device is that it is a one size fits all for the femoral popliteal space. The mechanism resides in the three radially opposed precision atherotomes that are attached to a basket that can be expanded from a low profile, relaxed state, to a higher profile “spring” loaded configuration. The atherotomes are mounted on skids that allow the atherotomes to glide smoothly and make precise incisions in the plaque without perforating. With two passes, we have six contiguous, longitudinal micro-incisions, along whatever length of the vessel the interventionalist chooses. This sets the vessel up for a more effective balloon angioplasty and in our initial clinical cases, we are seeing very low balloon-opening pressures. This has translated to a much lower rate of dissection, and less need for stenting.
Dr. Mustapha: It seems this device might reduce the time to prep the vessel.
Dr. Pigott: Certainly that is what we have seen in over 100 clinical cases we have completed thus far. Each pass of the device takes less than one minute, even for extremely long lesions. Our average lesion length to date is 130 mm, with half of our cases being lesions greater than 100 mm. So, this is less time in radiation than current available atherectomy devices or specialty balloons.
Dr. Mustapha: Lesions rich in elasticocarcinosis (a pathology term defined as the combination of hypertrophied elastica interna, in combination with intimal calcification ± medial calcification) lead to a nightmare of acute luminal loss due to recoil. Do you believe that the Flex device releases this restrictive combination, therefore reducing acute luminal loss, subsequently increasing acute luminal gain?
Dr. Pigott: I do believe that this is true. I think that a lot of it is based not only on the acute results we are seeing on a clinical basis, but with the decreased balloon pressures that we referenced earlier. We have some early intra-procedural duplex ultrasound demonstrating that the Flex leads to markedly improved acute luminal gain prior to use of balloon angioplasty. Many of our interventionalists are going straight to a drug-coated balloon after Flex, and eliminating prep with a regular balloon as an interim step, as they are seeing that the Flex device releases the restrictive combination discussed above.
Dr. Mustapha: It seems, based on what you have shared, that the Flex device is basically a quick way of removing the obstacles and creating a well-prepared vessel. Hence, a good, quick vessel prep tool.
Dr. Pigott: Just last week, we had a patient urgently added on to the schedule at the end of the day. With a diagnosis of rest pain, he had a 250 mm long chronic total occlusion (CTO) of the superficial femoral artery (SFA). The lesion was crossed with a guidewire and support catheter. The Flex procedure was performed and two drug-coated balloons were used. The patient noted resolution of his rest pain prior to his discharge later that day. The procedure was extremely quick, the patient had an excellent technical result, and I even got to go home early that day. So it is very rewarding as an interventionalist to conceive, design, and develop a product that produces safe and effective outcomes.
Disclosure: Dr. Mustapha reports he is a consultant for Bard, Covidien, Cordis, CSI, Spectranetics, Boston Scientific, Cook, and Terumo. Dr. Pigott reports he is the founder, chair, and chief science officer for VentureMed Group.
Dr. J.A. Mustapha can be contacted at firstname.lastname@example.org.
Dr. John Pigott can be contacted at email@example.com.
Treatment of a BTK Popliteal CTO With the Flex Scoring Catheter
Case study performed by and courtesy of Dr. David Paolini, Vascular Surgeon, Jobst Vascular Institute, Toledo, Ohio.
This is a 90-year-old female who is a smoker. She presented with critical limb ischemia with a great toe ulceration and rest pain. There was a palpable femoral pulse and no palpable pedal pulses. Her ankle-brachial index was 0.2. Contralateral access was obtained. The initial angiogram revealed irregular plaque in superficial femoral artery (SFA) without flow-limiting stenosis. The initial angiogram also showed a 5 cm, heavily calcified chronic total occlusion of the below-the-knee popliteal artery with reconstitution of 3-vessel runoff. We crossed with a Glidewire (Terumo) and support catheter. An exchange was made for an .018-inch wire. The Flex Scoring catheter (VentureMed Group) was inserted and passed two times through the CTO segment with successful re-canalization and immediate luminal gain. A 4.0 x 60 mm In.Pact Admiral drug-coated balloon (Medtronic) was then used as post Flex treatment. Final angiogram showed a widely patent popliteal vessel with no dissection and 3-vessel runoff to the foot. In the recovery room, the patient had a palpable dorsalis pedis pulse. She reported complete relief of rest pain prior to discharge.