Innovations in Electrophysiology
Electrophysiology (EP), as a subspecialty, is coming into its own. Electrophysiologists have access to more capital than in the past, and with a 10 to 15 percent annual market growth, it is one of the fastest growing sectors within cardiology. Vendors have taken notice and are focusing on technology and designs that cater specifically to EP docs.
Historically, in hospitals, cardiac surgery and interventional cardiology have driven financial growth. Today, however, cardiac surgery and cath lab volumes are down, as are their margins, while EP volume and its margins are up, says Laurence Epstein, director of electrophysiology at Brigham and Women’s Hospital (BWH) in Boston.
Driving from the cockpit
While EP is growing in stature, the labs are often crowded and cluttered with tangles of equipment and cables. Long, complex procedures are made more tedious by repositioning equipment, walking back and forth to the control room and working with dissimilar systems. The “EP Cockpit” from Philips Healthcare organizes the tangled mess of equipment into to one movable ceiling mount. The equipment is accessed from a tableside control panel. Cost is about $300,000.
The cockpit’s 56-inch, high-resolution monitor displays up to 16 inputs, including live and reference x-rays, hemodynamic data, intracardiac ultrasound (ICE), 3D mapping and video switching—which eliminates the need for half a dozen or more smaller monitors dotted throughout the lab. Physicians can preset the tableside interface to highlight any one of the inputs, such as ICE or 3D mapping, during the procedure.
At the Texas Cardiac Arrhythmia Institute at St. David’s Medical Center, in Austin, Texas, the cockpit allows for “a more rational placement of all the tools, a way to have a more functional lab with less chance of noise during the procedure,” says Andrea Natale, MD, executive medical director.
At BWH, the EP lab has a 56-inch screen from Carrot Medical, with similar “cockpit” capabilities. This model costs between $150,000 to $200,000, which can include an integrated wireless intercom system and the ability to record imaging in real time. Advances in the pipeline from Carrot, however, include gesture technology, which would allow physicians to manipulate images on the screen without touching it, like operating a Nintendo Wii. Physicians also will be able to “draw” on the screen without touching it. “If I need to measure a beat on the electrical signals and I point it out to someone, invariably that person never puts their cursor on the right beat. With this advanced technology, I’ll be able to circle the area with my fingers without touching the screen,” says Epstein.
The EP Cockpit is the final piece that integrates all the technologies and allows easy access from one keyboard panel for Tom Lonergan, executive director of the Hoag Heart and Vascular Institute at Hoag Memorial Hospital Presbyterian, Newport Beach, Calif. “That is where the edge of the universe is for EP right now,” he says. “You want to have the right tools, but you want them all integrated into a seamless system that makes it operationally efficient from a business standpoint, reduces procedure time, lowers costs and improves outcome.”
Balloons, robots & 3D imaging
Having technology like the cockpit helps electrophysiologists, especially during long, complex ablations for atrial fibrillation (AF) and ventricular tachycardia (VT). Advances in ablation technology such as 3D mapping and remote robotic catheter navigation have enabled the growth of radiofrequency ablation (RF) procedures for AF and VT. But even RF ablation is challenging, says Epstein, which is why research is ongoing into other ablative therapies, such as cryo-balloons, laser balloons and high-intensity focused ultrasound balloons. “In about a decade, we might even be able to deliver focused ultrasound energy from outside the heart,” says Epstein.
The use of remote robotic navigation is gaining momentum for several reasons: it delivers better precision than manual navigation, allows physicians to place mapping catheters in hard-to-reach anatomical locations within the heart with stability, and spares the operator radiation exposure during long procedures. Two robotic systems are available: Stereotaxis Magnetic Navigation System and Hansen Medical Sensei Robotic Catheter System. Stereotaxis costs about twice as much as Hansen and has considerable siting requirements—but it has been around longer, which has created a certain comfort level with the many EPs who have trained on it, says Lonergan.
Hansen uses a steerable sheath to guide the catheter, while Stereotaxis uses magnets. The Hansen sheath currently is not long enough to perform VT ablations, but the company plans to have one on the market soon.
Natale and his group have both systems and preference varies among physicians. The Stereotaxis is primarily used for VT and the Hansen for AF. Now that the ThermoCool catheter (Biosense Webster) is FDA-approved, however, the group is increasingly using the Stereotaxis system for AF.
A key feature of the Hansen system that Epstein considers an advantage is a force sensor at the tip of the catheter that allows the operator to determine how much force is being used to push the catheter against the heart wall. “We need to collect data on this, but perhaps you will be able to titrate the force to improve lesion formation,” he says.
One of the reasons why EPs can better treat AF with ablation is because of the advances in 3D imaging technology. Pre-procedural CT and MR images are easily integrated and superimposed onto live fluoroscopy images, helping EPs better navigate within the heart. And now, 3D rotational atriography overlaid images have proven promising and may replace the need for pre-procedural CT scans. Studies confirm its ability to reduce radiation dose compared with pre-procedural CT scans. Advanced software programs also create 3D electro-anatomical maps of the heart that can be interfaced with remote or tableside catheter movement. Lonergan says that the 3D mapping systems are so good that they preclude the need for a second x-ray plane. “From a business standpoint, that $400,000 savings is a big deal.”
In the future
Because MRI provides better tissue detail than fluoroscopy, research is ongoing to develop MR-compatible equipment for the EP lab to be used intraoperatively to guide catheters. Another area of research involves developing a real-time feedback sensor that gives physicians an accurate assessment of the RF lesion. And the EP lab of the future also might allow physicians to mark the screen where ablation will take place, hit a button and the ablation automatically commences.
| Lead extraction requires skill, comprehensive tool set |
| As more people receive implantable cardiac devices, the need to remove infected or defective leads increases. Because scar tissue can bind the lead in several places along its length, lead extraction demands expertise, as well as a plethora of specialized tools and immediate cardiac surgical backup. The main extraction tools include laser and radiofrequency ablation, mechanical rotational sheaths and manual traction. In years past, it was common to leave non-functioning leads inside patients as long as the leads were not directly causing a problem. Today, physicians have learned that this could lead to infection or venous occlusion and they have become increasingly proactive in removing malfunctioning leads. Recent studies demonstrate the safety of lead extraction using a variety of techniques. Laser Researchers from Brigham and Women’s Hospital (BWH) in Boston reported the extraction of nearly 1,000 leads from almost 500 patients in a seven-year span, resulting in a 98 percent success rate (Heart Rhythm 2008;5:520-525). Nearly 80 percent of extractions used laser assistance (CLeaRS, Spectranetics), while the rest were done with manual traction. Independent predictors of the need for laser were implant duration and the presence of an implantable cardioverter defibrillator (ICD) lead. There were two major complications (cardiac tamponade, both with laser). Senior author Laurence Epstein, MD, director of the electrophysiology laboratory at BWH, said that lead extraction is the one procedure with the largest learning curve. “The feel is the most important thing,” he says. “You have to pull hard enough to track the sheath over the lead, but not too hard that the lead breaks. That is where experience comes into play.” Radiofrequency Czech researchers, led by Vivek Y. Reddy while at the Massachusetts General Hospital, equally randomized 120 patients to RF-assisted extraction (Perfecta, Cook Medical) or manual traction (Europace 2007 9(2):98-104). They wanted to find a less expensive alternative to laser. Success with RF was higher (93 vs. 73 percent), including a better rate of ICD lead removal and reduced time. Three patients—one in the standard and two in the RF arm—had serious bleeding complications. Some reports suggest that laser and RF devices are more prone to cause perforations. Charles J. Love, MD, director of arrhythmia device services at Ohio State University in Columbus, disagrees, saying that perforations are associated more with operator experience rather than with any one technique. Mechanical Charles Byrd, MD, a clinical professor of surgery at the University of Miami School of Medicine, Fla., and researchers used a mechanical device (Evolution, Cook Medical) to extract 130 of 131 leads from 67 consecutive patients (2007 Venice Arrhythmias Congress, Italy). They experienced two complications: a bleed into the right chest unrelated to the device and a small tear in the superior vena cava by the outer sheath that required no surgical repair. Mechanical sheaths are particularly effective with heavily calcified scar tissue and are relatively inexpensive, less than $100. Laser sheaths cost upwards of $2,000, while the cost of RF sheaths falls somewhere between the two. Experts recommend having all types of tools available. “Lead extraction is not a procedure that allows for one single tool to be successful in the majority of cases. It’s like trying to fix your car with one wrench. You want to have every tool possible to be as successful as possible,” says Love. |