Sensei robotic catheter system

Hansen Medical offers a robotic catheter placement device, the Sensei Robotic Catheter System, which uses a system of pulleys to navigate a steerable sheath for catheter guidance. The Sensei obtained U.S. Food and Drug Administration (FDA) approval in 2007, after which the Cleveland Clinic's electrophysiology program, then directed by Dr. Andrea Natale, received the first placement. The Sensei provides the physician with more stability and more force in catheter placement with the Artisan sheath compared to manual techniques, allowing for more precise manipulation with less radiation exposure to the doctor, commensurate with higher procedural complications to the patient, including cardiac perforations, tamponade and femoral artery injuries. Centers have reported acute and long term success rates consistent with manual procedures. Hansen Medical was founded by Dr. Frederic Moll, who had also co-founded Intuitive Surgical, maker of the Da Vinci Surgical System, whose use has propelled medicinal robotics to the forefront. The system is indicated for use in mapping, but largely it is used in off-label procedures for the treatment of Atrial Fibrillation (afib), as well as in structural cardiology with the company's acquisition of AorTx.

As of June 30, 2009, over 68 Sensei systems have been installed across the world, with over 2000 procedures performed. The Sensei operates by guiding standard catheters through a manipulated sheath in the patient's vasculature. The doctor performs the procedure at a side cart with a technology called "IntelliSense" to deduce forces applied. IntelliSense mathematically estimates the pressure the catheter exerts on heart tissue. Because of the sheath's multiple degrees of freedom, force detection at the distal tip has remained a challenge for Hansen's engineers. The sheath is 14 French in size, allowing for standard size catheters to be used. The Sensei has FDA clearance for mapping procedures only, but doctors continue to experiment with the system for ablation.

Clinical data and other reports

Off-label usage

The system has encountered some skepticism from the academic community, in some studies achieving complication rates as high as 19% and also having reports of autonomous sheath movement during procedures. Doctors continue to use the system for ablation procedures despite the FDA's requirement that Hansen Medical place a sticker on the system and advertisements to warn doctors and patients that the safety of the system for ablation has not been demonstrated. The following is a label that the FDA requires Hansen to provide on its website, the Sensei system itself, and all advertisements:

The safety and effectiveness of this device for use with cardiac ablation catheters, in the treatment of cardiac arrhythmias including atrial fibrillation, have not been established.

Despite the FDA requirement for this label, Hansen Medical continues to advertise for the treatment of AF with the Sensei robot. Dr. Frederic Moll, CEO of Hansen Medical, recently mentioned in a JP Morgan presentation on December 5 that atrial fibrillation procedures total 77-80% of all procedures conducted with the Sensei robot.

Procedural complications and patient mortality

Despite hundreds of procedures at academic universities and FDA approval, clinical data and disclosures in the company's SEC filings indicate that perforations and safety concerns remain an issue. The system firmly places the catheter on the heart wall during ablation, which can lead to tenting of the heart muscle and ultimately perforation. Additionally, the large diameter Artisan Sheath (14F compared to 7F for most cardiac catheters) has led to fistulas and damage to femoral arteries around the groin, where catheters are inserted. At the American College of Cardiology 2008 conference, Biosense Webster submitted Manufacturer and User Facility Device Events (MAUDE) filings to avoid confusion about perforation, thrombosis and tamponade complications from use with the Hansen system. In addition to the five complications reported through Biosense, Hansen has another fifteen officially reported complications since its approval in late 2007. Additionally, Hansen has failed to report several complications to the FDA in off-label procedures, including one in which the 14F Artisan Sheath punctured a femoral artery in a procedure in May, 2009. In the adverse event recorded on August 12, the Artisan Steerable Sheath had "non-instinctive driving," similar to a report filed earlier in 2008. On September 11, 2008, a patient died when undergoing a procedure with the Sensei system, due to a perforation from an Artisan Sheath.

Reports of clinical data

Results determining the efficacy and safety of the Sensei system compared to manual procedures has been mixed and inconclusive. Several centers report higher acute success rates compared to manual, commensurate with higher complication rates and procedure times, though with lower flouroscopy dosage to the operator. Large centers with experienced operators tend to achieve complication rates similar to manual procedures, while smaller centers such as the Lahey Clinic obtain complication rates as high as 17%. Recent clinical data presented by Dr. Gallinghouse showed 94% PAF patients free of AF & 87% CAF patients free of AF with low complication rate. These results indicate that robotic navigation of catheters for ablation of atrial fibrillation can be safe and effective for the selected sample of patients under highly skilled physicians, and that fluoroscopy and procedure times decrease with experience in that particular sample. A leading electrophysiologist, Andrea Natale, was one of the chief advocates of the Sensei system. However, at Heart Rhythm Society 2008 he deemed the technology "was not for (him)" after achieving a 19% complication rate, much higher than the average 4-5% rate for manual ablations.

• In an early study, 9 out of 48 patients incurred life-threatening injuries during Sensei procedures. Three of the complications were "significant" vascular injuries, including iliac vein stenting and cardiac tamponade.
• A 2008 report related to worldwide usation of the Sensei system for A fib showed no procedure-related mortality. Vascular complications were reported in 0.7% of patients and in 1.3% of patients periricardial effusion occurred intra-operative or early after the procedures.
• Saliba and Reddy (2008) investigated the Sensei system in a trial with 40 patients with atrial fibrillation using PV and SVC isolation. 85% of patients were free of atrial fibrillation at 12 months, and the investigators reported a 5% complication rate (n=2) encountering pericardial tamponade.
• Barrett and Wazni led a study using the Sensei robot for 48 patients with atrial fibrillation. One procedure was aborted due to a vascular complication and another due to a thickened septum. The investigators determined that treatment in the coronary sinus was not feasible: "Ablation within the CS was not completed with the system in any patient, and was performed manually in 12 patients. The CS ostium could be entered in the majority but further advancement of the catheter was unsuccessful or was felt to be unsafe."
• In a more encouraging study, doctors from the Texas Cardiac Arrhythmia Institute performed 162 ablation procedures, with 106 consisting of paroxysmal AF and 56 of chronic AF. PVAI was obtained in all patients, with 29 out of 32 patients (90%) free of AF at 6 months of follow up. Three major complications were reported, two of which were pericardial tamponade and one femoral pseudoaneurysm.
• Barnebei et al. (2009) report a 17% complication rate in 35 procedures with the Sensei system, including 3 retroperitoneal hemorrhages, 2 cardiac tamponades as well as a pericardial effusion. Additionally, they found that "in this early single-center experience comparing robotic and manual catheter ablation for AF, the robotically controlled catheter system was associated with a longer procedure time, more complications, and a trend toward fewer recurrences of symptomatic atrial tachyarrhythmia."
• An abstract presented at HRS 2009 from Gallinghouse et al. at the Texas Cardiac Arrhythmia Institute finds "Robotic navigation of catheters for ablation of atrial fibrillation appears to demonstrate equivalent safety relative to manual navigation, and may offer efficacy advantages in our single center experience. Fluoroscopy and procedure times are similar."
• Servatius et al. from the University Heart Center Hamburg Eppendorf noted that "Higher recurrence rates of the right PVs may suggest a more challenging accessibility of the septal side of the LA using the RNS. Recurrence of PV conduction is frequently encountered after initially successful PVI and may be reduced but not completely eliminated by using RNS."
• In a study of 65 patients, Tilz et al. from St. Georg Hamburg achieved a 4.6% complication rate and an acute success rate of 95%. One procedure had to be aborted because of a malfunction of the Sensei Robot. Further, the long term success rate after an average of 239 days fell to 73%, and the investigators remark, "Achieving catheter stability at the anterior left PV ostium remains a challenge."
• R. Liew et al. (2009) achieve a 6% complication rate in a sample of 33 patients. Additionally, they record longer procedure times on the Sensei versus manual (259 min vs. 289 min), and 35% of the Sensei patients were listed for touch up procedures compared to only 28% for the manual sample.

Reports from Dr. Natale and other doctors using the Sensei have raised concern that many more adverse events have occurred with system usage in the U.S. than the documented 18 in the MAUDE database. Additionally, European complications are not reported to the FDA, and close to a third of Sensei placements are in Europe. This calls into question the Hansen CEO, Dr. Frederic Moll's claim that the Sensei system achieves a similar complication rate as manual procedures, as a substantial portion of Sensei procedures are performed in Europe.

Product recall

On May 21, 2008, the company recalled a batch of Artisan catheters that had a manufacturing malfunction that could lead to leaks during the procedures. According to Doug Worth, Director of Regulatory Affairs at Hansen Medical, at least 10 procedures were affected by this problem. A leak "in the flexible bellows portion of the catheter has the potential to cause, among other things, loss of haemostas, flush fluid leakage and/or introduction of air into the catheter with a risk of subsequent embolism."

Artisan S Catheter

The company received FDA 510K clearance for an extension of the Sensei Robotic Catheter System platform, called the "Artisan S Catheter." The company has yet to make formal recognition of this product in a press release or a filing with the SEC, which is customary for material events like a new product clearance. The Artisan S Catheter is substantially similar to the original Artisan catheter according to the FDA filing. Apart from that, little has been disclosed by Hansen about the device.

Sites

United States

• Scottsdale Healthcare Osborn, AZ
• Scripps Health, San Diego, CA
• Sequoia Hospital, CA
• University of Miami Hospital, FL
• Emory Crawford Long Hospital, GA
• St. Luke's Hospital, IA
• Loyola University Hospital, IL
• Brigham and Women's Hospital, MA
• Massachusetts General Hospital, MA
• University of Maryland Medical Center, MD
• Duke University Medical Center, NC
• Mount Sinai Hospital, NY
• Cleveland Clinic, OH
• Riverside Hospital, OH
• VA Brecksville Hospital, OH
• Midwest Regional Medical Center, OK
• Oklahoma Heart Hospial, OK
• St. Lukes Baptist Hospital, TX
• The Methodist Hospital, TX
• St. David's Hospital, TX
• University of Virginia Medical Center, VA
• University of Mississippi Medical, MS

Europe

• St. Georg Hospital, Germany
• University Hospital Hamburg-Eppendorf, Germany
• Imperial College Hospital, London, United Kingdom
• St. Bartholomew's Hospital, London, United Kingdom
• St. Mary's Hospital, London, United Kingdom
• St. Thomas' Hospital, London, United Kingdom
• John Radcliffe Hospital, Oxford, United Kingdom