Atherectomy: Back to the Future
"The angiographic catheter can be more than a tool for passive means for diagnostic observation; used with imagination, it can become an important surgical instrument.”
-Charles T. Dotter, 1920-1985
The prophetic words of Dr. Dotter from the Czechoslovak Radiological Congress on June 19, 1963 ushered in a major turning point for the management of vascular atherosclerotic disease. Engineers, physicians, and entrepreneurs from around the globe have answered the call of Dr. Dotter by arming us with an abundance of catheter based devices to combat vascular disease. In 1974, the revolutionary work of Dr. Andreas Gruentzig provided us with balloon angioplasty. After its rapid and enthusiastic adoption, complications of elastic recoil, spasm, intimal dissection, abrupt closure and restenosis motivated others to imagine alternative or adjunctive means for treating atherosclerotic occlusive disease. The pioneering efforts of Dr. John B. Simpson in the 1980s led us to the next major breakthrough in vascular interventions which was plaque modification by atherectomy.
Today, atherectomy plays an important role in the percutaneous management of patients with peripheral vascular disease. There are many atherectomy catheters currently available that have varying mechanisms of action such as directional cutting, differential cutting with rotational or orbital atherectomy, photo-ablation with excimer lasers, and rotational cutters with continuous or active removal of plaque debris. Needless to say, these devices are the culmination of decades of ingenuity, technological advancements, and clinical experience.
The readership of Vascular Disease Management includes a diverse group of scientists, technicians, and interventionists with a wide spectrum of clinical experience. Many are pioneers in our field who have first-hand experience during the early days of atherectomy. On the other hand, many, including myself, were only afforded the stories passed on from our more senior colleagues. Recently, I had the privilege to investigate the early days of atherectomy in a comprehensive review for an upcoming publication. What I learned is that the story of atherectomy is a fascinating one (and perhaps terrifying to some). The current generation of atherectomy devices all share common principles with the original devices, albeit with the added benefit of 30-years of technological improvements and experience.
The first device was a directional atherectomy catheter. After a failed balloon angioplasty, Dr. Simpson closely studied a Cope pleural biopsy needle and imagined its potential to shave atheroma. This concept became reality with the creation of the Simpson AtheroCath in the early 1980s. This was the first major interventional device since balloon angioplasty to gain approval by the FDA. The original peripheral AtheroCath consisted of a rigid metal housing unit that enclosed a cylindrical metal cutting blade with a Surlyn balloon mounted on the opposite side of the housing. Adjacent to the metal housing was a flexible distal nose cone to collect excised atheroma and a short 0.018" floppy wire (0.046cm) to assist catheter advancement and steering. Inflation of the balloon caused plaque to be forced into the cutting window where a battery powered cutter shaved atheroma at 2,000 rpm. After deflation of the balloon, the housing was re-aligned for the next cut. The original catheters were bulky and as large as 11 Fr. The affixed balloon was responsible for some of the luminal gains which was not the intended goal. Complications with these devices ranged from 2% to 10% as a consequence of access related complications, thrombosis, dissections, perforations and distal emboli.
The second device to gain FDA approval in the late 1980’s was the transluminal extraction catheter (TEC) which was invented by Interventional Technologies, Inc. (San Diego, California) and developed in conjunction with Richard S. Stack at Duke University. TEC was a 0.014”, over-the-wire based cutting and aspiration system that consisted of a conical cutter composed of two imbedded stainless steel blades attached to the distal end of a semi-flexible, hollow torque-tube. The battery powered cutter had microtome-sharp edges that rotated at 750 rpm when activated, and the debris was collected in a 125-cc vacuum bottle irrigated with warmed Lactated Ringer’s solution. The peripheral devices were up to 11 Fr. It was suggested that a “Dotter effect” was partially responsible for some of the luminal gains. TEC was challenging to use in tortuous anatomy and prone to access related complications, thromboembolism, catheter fracture and anemia when aspiration was excessive.
Other atherectomy devices developed in the 1980s include the Auth Rotablator and XeCl Excimer Laser. These devices have stood the test of time with modified and improved iterations available today. David Auth, a renowned biomedical engineer, began development of the Rotablator in 1981. The first successful case of rotational atherectomy was performed in peripheral vessels (iliac, SFA, and popliteal arteries) by Zacca and colleagues in 1989. Original burr sizes for peripheral applications were as large as 6mm requiring up to 14-Fr sheaths. Laser atherectomy started with neodymium (Nd):yttrium aluminum garnet (YAG) [1060nm] and argon [500nm] lasers. These devices created significant thermal injury. The Argon “hot” tip probe was FDA approved for peripheral vessels, but lost traction given propensity for complications, including perforation rates as high as 4.1%. The 308nm XeCl excimer laser was pioneered by Grundfest and colleagues in 1985. As opposed to other atherectomy devices, this was first approved for use in coronary arteries in 1989, and only received FDA approval for use in peripheral vessels in 1992. Other atherectomy devices were developed in the late 1980’s that did not achieve widespread momentum such as the Pullback Atherectomy Catheter (PAC) and Trac-Wright device. I’m sure some readers familiar with PAC may recall inflating a blood pressure cuff on the lower extremity to achieve luminal gains.
When we go back to the earliest days of atherectomy, what we realize is how it has greatly shaped the procedure today, and how it will continue to do so in the future. From the original Simpson AtheroCath to the newer devices from Covidien and Avinger, directional atherectomy remains a viable tool with markedly improved catheter designs. Sharing some properties of the TEC device, we now have the Jetstream Atherectomy System (Boston Scientific Corp.) which allows a front cutting mechanism with active aspiration of debris, and expandable blades for creation of lumens larger than the catheter shaft. Another front cutting device with a deflectable tip, Phoenix catheter (Volcano Corp.), utilizes Archimedes screw technology to continuously cut and remove debris. Orbital atherectomy (Cardiovascular Systems, Inc.) share differential cutting features of the Rotablator, but has a differing mechanism of action. 308nm XeCl Excimer Laser (Spectranetics Corp.) has become an approved therapy for treatment of in-stent restenosis in femoropopliteal disease.
The newer generation of interventionists owe a debt of gratitude to the early adopters of atherectomy. Through their trials and tribulations (and bravery), atherectomy has now become a relatively simple procedure. For those who have lived through the early days of atherectomy, we would be honored to hear about your experience (the good, the bad, and the ugly).
