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Vibrating catheter can penetrate occlusions in blocked vessels
Crosser system could be an advance in the mechanical frontier of coronary arteries.
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A new type of vibrating catheter has the ability to break through the calcified blockages in totally occluded vessels.
The Crosser system, engineered by FlowCardia Inc. of Sunnyvale, Calif., consists of a generator and a vibrating catheter. The system is in trials to evaluate its safety and effectiveness in the clinical setting. According to some researchers, the device may provide a cost-effective alternative to percutaneous coronary intervention in some patients should it yield favorable data from larger clinical trials.
The Crosser system
Currently, the Crosser system is used when a traditional wire procedure attempting to cross a total occlusion has failed. The system is composed primarily of two components. The generator converts AC power into a high-frequency current, which is converted by a transducer into a high-frequency vibration that is transferred to the tip of the catheter. The catheter itself is a nitinol-core wire that transmits that vibrational energy from the generator to the tip of the catheter. The catheter is designed as a monorail system, following a 0.014 inch or 0.018 inch guide wire to the occlusion.
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“Chronic total occlusions are one of the last
mechanical frontiers in terms of reopening coronary
arteries.”When the targeted occlusion is reached, the stainless steel tip of the catheter, vibrating at 20,000 cycles per second, is pushed into the occlusion. The high-frequency vibration functions as a cutting force and the catheter pierces through the occlusion, allowing the guide wire entry into the lumen where a balloon or a stent can be delivered. The activation of the vibrating catheter is controlled by a foot pedal used by the interventionalist.
“Chronic total occlusions are one of the last mechanical frontiers in terms of reopening coronary arteries, so seeing advances in that area is really important because it’s been a very difficult area to fix,” George Vetrovec, MD, chairman of the division of cardiology at VCU Medical Center and member of the Interventional Cardiology section of the Cardiology Today editorial board, said in an interview. “With improved imaging, we’re probably at a good time now to address these blockages knowing the direction the total occlusion traverses. The problem has always been matching safety to success in total occlusions. This kind of vibratory mechanical method has a lot of potential for success and relative safety.”
Preliminary studies
To date, results of several preliminary studies using the Crosser system have been published, and other studies are ongoing.
Most of the available study results demonstrate that the Crosser system is between 65% and 80% effective in achieving endpoints of revascularization and crossed occlusions.
One was a prospective registry conducted in four European centers. The researchers enrolled 53 patients with CAD and 55 chronic total occlusions. The study was divided into a feasibility phase to assess safety and locate design flaws and a pivotal phase to implement the updated design and to assess efficacy. A total of 30 chronic total occlusions were treated in the feasibility phase and 25 in the pivotal phase. The primary endpoint of device efficacy and secondary endpoint of clinical success were both met in 19 of the 25 occlusions (76%) in the pivotal phase of the study. No major adverse cardiac events, Q-wave MI, perforations or target lesion revascularizations were observed in the follow-up period of 30 days. The results of the study were published in The Journal of Invasive Cardiology.
Another feasibility study of the device was known as the FlowCardia’s Approach to Chronic Total Occlusion Recanalization (FACTOR) trial. This trial also yielded an acceptable safety and efficacy profile, encouraging continued research and development of the device.
“What we found was the device was exceptionally effective and safe and was able to cross approximately, depending on the study, 70% to 80% of chronic total occlusions after failure of a routine wire procedure,” Louis Cannon, MD, FACTOR investigator and program director of the new Northern Michigan Hospital Heart and Vascular Institute, told Cardiology Today. “The safety issue is very big, because previous devices have not been this safe. We found that there were no perforations whatsoever with the device, and that is with very robust use. When we’re really trying to get through the total occlusion and we’re pushing extremely hard with big backup catheters and heavy wires, it still had no perforations.”
One ongoing clinical trial in the United States is evaluating the efficacy of the Crosser system in the peripheral vascular setting. The trial is called the Peripheral Approach To Recanalization In Occluded Totals (PATRIOT) study, which finished enrolling participants in September. The researchers of the study are examining the efficacy of the Crosser system in chronic total occlusion revascularization within the lower extremities.
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Courtesy of FlowCardia |
Cautious optimism
The Crosser system received 501(k) clearance from the FDA in January. The trends in preliminary data from the U.S. studies and those conducted in Europe suggest promise for the device, but some feel cautiously optimistic about any new technology like the Crosser system.
“I think that 70% to 80% is good, particularly with low complications,” Vetrovec said. “The caveats that need to be examined are the extent to which this device saves time, such as physician time, cath lab time, radiation and the extent to which the device perhaps is more efficient in terms of less total equipment use. Those are some issues that need to be further examined to determine what the device’s impact would be in addition to just opening up total occlusions in arteries.” – by Eric Raible
For more information:
- To learn more about the Crosser system, visit www.flowcardia.com.
- Grube E, Sutsch G, Lim V, et al. High frequency mechanical vibration to recanalize chronic total occlusions after failure to cross with conventional guide wires. J Invasive Cardiol. 2007;18:85-91.