Medical Device Daily Contributing Writer

NEW ORLEANS – Once thought of as an arcane and boring sub-specialty, the field of electrophysiology (EP) has blossomed in the past decade, fueled primarily by the incredible clinical and commercial success of implantable cardioverter-defibrillators (ICDs).

The impressive growth in the EP field is best exemplified by the fact that the membership of the Heart Rhythm Society (HRS; Washington) has nearly quadrupled in the past 15 years.

While ICDs certainly were prominent at numerous sessions and posters at last week’s Heart Rhythm 2005, the 26th annual scientific sessions of HRS, other emerging technologies certainly enjoyed the limelight in the four-day meeting at the Ernest N. Morial Convention Center.

Although totally dwarfed in size by the $4 billion domestic ICD market (which also includes devices for cardiac resynchronization), catheter ablation nevertheless is an important aspect of the interventional EP market, as it addresses important arrhythmias that remain huge clinical problems.

Specifically, atrial fibrillation (AF) is an ongoing conundrum for patients and their physicians, as its prevalence and incidence not only continues to increase with the aging population, but its exact causes and, more importantly, successful therapies remain elusive.

Over the past five years, catheter ablation of AF has evolved from an experimental procedure to one that is commonly performed throughout the world. In the US, for example, an estimated 15,000 ablations to treat AF ablations are being done annually, with at least that many outside the U.S. The lion’s share of AF ablations are aimed at left atrial pulmonary vein (PV) ablation. EP experts generally agree that AF is triggered in most patients by arrhythomogenic tissue that exists in the pulmonary vein.

Speaking at an evening symposium held during the HRS gathering, Hugh Calkins, MD, director of the EP lab at the Johns Hopkins Hospital (Baltimore, Maryland), stated that the rapid growth of AFib ablation reflects “encouraging reports of the safety and efficacy of the procedure.”

Yet, much progress remains, as the clinical results are far from sterling. At an HRS session titled “Imaging, Mapping and Ablation from 2005 to 2010,” Riccardo Cappato. MD, of the Policlinico San Donato (Milan, Italy), reported on a worldwide survey of nearly 9,000 AF ablations that were performed at 100 centers between 1995 and 2002. Cappato noted that the reported success rate, defined as free of any medical management after six months, was a modest 52%, with another 24% experiencing reduced drug needs.

He noted that these results were probably even poorer, since hospitals that did few procedures did not even respond to the survey. “Clearly, we need to do better than this” to make ablation the procedure of choice, he said.

One of the EP community thought leaders, Karl Heinz Kuck, MD, of the Algemeines Krankenhaus St. Georg (Hamburg, Germany), delivered an excellent talk on how new energy sources, such as high-intensity focused ultrasound (HIFU) lasers and cryothermia will improve the results of AF ablation. Regarding HIFU, he cited the impressive technology of ProRhythm (Ronkonkoma, New York), which features a steerable catheter that is focused via a reflecting balloon configuration to deliver sufficient energy to achieve ablation to the pulmonary vein. ProRhythm’s technology is currently being evaluated in clinical trials in both Europe and the U.S.

ProRhythm (formerly known as Transurgical) reported early this year (Medical Device Daily, Jan. 6, 2005) that it entered into a number of agreements with St. Jude Medical (St. Paul, Minnesota), providing, under certain conditions, for St. Jude to make two $12.5 million minority investments in ProRhythm, which the company anticipates will occur in 2005. The agreements also provide St. Jude with the exclusive right to acquire ProRhythm for $125 million in cash, with additional cash payments payable to the ProRhythm shareholders after completion of an acquisition if ProRhythm achieves certain milestones.

Citing several relatively recent innovations and developments now under way, Kuck concluded his HRS talk by saying that “the automation of mapping and ablation could become the standard of care by the year 2010.”

In a similar vein, renowned EP expert Douglas Packer, MD, of the Mayo Clinic (Rochester, Minnesota), indicated “the integration of mapping, guidance and ablation will be commonplace by 2010.” He said he is particularly enthused with 3-D MRI and computed tomography (CT), intracardiac echocardiography (ICE) and remote and image-guided robotic technologies.

Improved imaging technologies and more precise navigation devices were clearly on display at this year’s HRS meeting. Both EP MedSystems (West Berlin, New Jersey) and Siemens Medical Solutions (Malvern, Pennsylvania) prominently featured their ICE product lines. The latter pioneered this technology and is the undisputed market leader, which is now increasingly being used in PV ablations. The former, which entered the market in 2004, recently initiated a multi-center, randomized US study called Intra-Cardiac Echo-cardiography Guided Cardioversion to Help Interventional Procedures (ICE-CHIP), which will investigate the potential role of ICE in the cardioversion of AF patients.

EP Medsystems and Philips Medical Systems (Andover, Massachusetts) have recently concluded a multi-platform joint development agreement, to provide the most technologically advanced EP products. An initial collaboration has already occurred in the area of EP recording systems and this will likely evolve to a joint effort in the ICE area.

Innovative mapping technologies that have appeared in the last few years have clearly improved the safety and efficacy of catheter ablation. These include the CARTO, a 3-D, color-coded cardiac mapping and navigation system from Biosense Webster (Diamond Bar, California), a division of Johnson & Johnson (New Brunswick, New Jersey), the EnSite non-contact cardiac anatomical mapping technology from St. Jude Medical (St. Paul, Minnesota) and the Realtime Position Management (RPM) ultrasound catheter-based technology from Boston Scientific (Natick, Massachusetts). Many EP labs have acquired one of these technologies in recent years.

While 3-D MRI and CT will enhance these technologies, an exciting new area in interventional EP is in catheter navigation systems. A recently new public company, Stereotaxis (St. Louis), is the most prominent player at the moment. Its magnetic assisted intervention system consists of proprietary catheters, guidewires and stent delivery devices along with a computer-controlled, externally applied magnetic field that precisely and directly govern the motion of these devices. The goal is to bring precise remote digital instrument control and programmability to interventional procedures.

The range of procedures is enormous, spanning EP, cardiology and other interventional disciplines. Clinical results to date are positive and appear to validate the technology. For example, in a series of relatively simple supra-venticular tachycardia ablations, both the procedural time and fluoroscopic time were cut significantly. In a study of left ventricular lead implants comparing conventional navigation to magnetic navigation, the procedure time again was reduced significantly, with a further benefit that the number of disposable supplies was reduced.

Speaking at a company-sponsored evening symposium, Ruchir Sehra, MD, Stereotaxis’ chief technology officer, indicated that his company has sold 30 systems worldwide (including 20 in the U.S.) and that approximately 1,600 cardiology procedures have been performed to date. The company has important strategic alliances with Siemens, Philips and Biosense Webster.

Warren Jackman, MD, director of clinical electrophysiology at the University of Oklahoma Medical Center (Oklahoma City), recently said that the Stereotaxis system “defines a new era in interventional medicine, one where computers and software provide an opportunity to help physicians navigate devices more precisely and efficiently.”

Debuting at HRS, privately owned, venture capital-backed Hansen Medical (Mountain View, California) was clearly one of the highlights of the meeting. The company was founded in 2002 by Frederic Moll, MD, who also was a founder of the enormously successful Intuitive Surgical (Sunnyvale, California), and Rob Younge, a co-founder of Intuitive. Hansen’s goal is to provide safe, accurate and efficient control over catheter movement during interventional procedures. Ideally, this precision will lead to faster procedures as well.

The basis of the system is an electromechanical robot, which the physician controls from a workstation that integrates visualization, guidance, and patient physiologic data. Once seated at the workstation the physician is able to instinctively guide the movement of diagnostic or therapeutic catheters with a “joystick” to the desired anatomic location.

Hansen’s exhibit, its first at HRS, was consistently buzzing with activity the entire show. In addition, several talks during the conference were highly favorable, as physicians extolled its ease of use, instinctive operation and simplicity. At an evening symposia, Andrea Natale, MD, of the Cleveland Clinic (Cleveland), said that in his feasibility trial, the system performed very well, reducing procedural time and demonstrating safety and efficacy.

“This is a very promising approach to EP catheter navigation,” he told a packed audience. Natale did caution, however, that because of the lack of tactile feel of conventional catheter manipulation, it would take time to get used to using the robotic system. “It is very different than what we are used to” he concluded.

Hansen said it hopes to attain FDA clearance via a 510(k) in the second half of this year. Final pricing of the system has not yet been determined, but CEO Moll told Medical Device Daily that he expects it will be priced at about half that of the Stereotaxis system, or somewhere in the neighborhood of $1 million.