A RF ablation guide wire with an optical coherence reflectometry guidance system has been developed to percutaneously open total occlusions in arteries. The ablation energy does generate heat as does any electrosurgical application of RF energy. Prior histology studies using this device had shown that the heat generated in the total occlusion was not a clinical concern. In this study, a novel fiber-optic based temperature measurement sensor was used to actually measure the temperature rise in an artery in vivo in a porcine model. The optical temperature measurement system is immune to RF emissions and interference and could be delivered in the same catheter as the guide wire. Temperature rises in the occluded arteries in a worst-case scenario were shown to be less than 10°C, localized to the volume adjacent to the ablation tip, and the temperature returned to ambient within a few seconds after the energy was no longer applied. The temperature data is in agreement with the prior histology studies.
There have been many innovations and technological advancements in balloon angioplasty since its introduction in the late 1970’s, but percutaneous intervention on a totally occluded artery is still a challenge to the vascular interventionalist. Catheter-based intervention that avoids an invasive surgical procedure is a clear and desired advantage for the patient. A total occlusion challenges the interventionalist because the path of the artery can not be seen in the occluded vessel since the flow of the radiopaque contrast media is blocked. Optical coherence reflectometry techniques have been shown to be able to differentiate between artery wall and occlusive materials allowing the lumen of the blocked artery to be seen inside the occlusion. During this past year, a guide wire that uses OCR for forward-looking guidance has received FDA 510(k) clearance and future generation devices that add radio frequency ablation capabilities are in clinical trials. Clinical results show that these new tools are addressing this subset of patients with percutaneous interventions with safety and effectiveness.
There have been many innovations and technological advancements in balloon angioplasty since its introduction in the late 1970's, but percutaneous intervention on a totally occluded artery is still a challenge to the vascular interventionalist. Catheter-based intervention that avoids an invasive surgical procedure is a clear and desired advantage for the patient. A total occlusion challenges the interventionalist because the path of the artery can not be seen in the occluded vessel since the flow of the radiopaque contrast media is blocked. Optical coherence reflectometry techniques have been shown to be able to differentiate between artery wall and occlusive materials allowing the lumen of the blocked artery to be seen inside the occlusion. Light emitting diodes are a critical component of these systems making them technologically possible and economically feasible.
One of the last remaining frontiers in angioplasty interventions is successfully recanalizing arteries containing total occlusions. The primary limitation is the inability to pass a guide wire safely across the total occlusion to facilitate therapeutic interventions, such as balloon angioplasty. The Optical Coherence Reflectometry (OCR) guide wire system has demonstrated clinical potential for navigating through total occlusions, but often these lesions are refractory to passage of the guide wire by mechanical force alone. The OCR guide wire has been coupled with low frequency (250-500 kHz), short duration (100 millisecond pulses) radio frequency energy to facilitate guided ablation through the total occlusion. Through a real- time monitoring system and display, the physician is warned if the guide wire approaches the normal arterial wall, allowing the guide wire to be redirected to prevent perforating the vessel. Coupled with the OCR guidance system, the RF ablation allows passage through highly resistant lesions that would not normally be transversed with conventional guide wires. The OCR guided RF guide wire system has been successfully tested in porcine models with cadaveric atherosclerotic diseased arterial grafts.
One of the last remaining frontiers in angioplasty interventions is successfully recanalizing arteries containing total occlusions. The primary limiting condition is the inability to pass a guide wire safely across the total occlusion to facilitate therapeutic interventions. The operator has to perform the intervention without the assistance of x-ray imaging to define the vessel's path since the contrast media flow is blocked by the occlusion. To overcome this limitation, a guide wire system has been developed that transmits low coherence near-infrared light through an optical fiber internal to the guide wire and illuminates the tissue adjacent the distal end. Differences in the scattering of near-infrared light by the normal arterial wall and occluding tissues are detected by optical coherence reflectometry (OCR) techniques. Through a real-time monitoring system and display, the physician is warned if the guide wire approaches the normal arterial wall, allowing the guide wire to be redirected to prevent perforating the vessel. The system has been used in clinical coronary angioplasty cases demonstrating the ability to cross 10 out of 11 total occlusions without any perforations or dissections. The OCR guide wire system has demonstrated clinical potential and will require additional testing for clinical efficacy claims.
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