Current multiple-optical-fiber catheters for excimer laser coronary angioplasty (ELCA) emit pulsed light at 308nm from a xenon chloride (XeCl) excimer laser to remove plaque in occluded arteries. Because the fiber ends, arranged in a closest- packed array, do not cover the entire surface of the catheter tip, these devices ablate holes typically holes typically 75-80 percent of the catheter tip diameter. To increase the ablation effectiveness, an optimally spaced fiber catheter has been designed in which the fiber-to-fiber spacing is increased precisely enough so as to cover the entire catheter tip area with fibers. In vitro and in vivo testing compared the optimally spaced catheter to catheter models currently in clinical use. Although device handling characteristics were found to be identical, the optimally spaced devices removed a significantly greater amount of tissue. This may offer a technical advantage in a clinical setting.
In response to recent demand for increased debulking of large diameter coronary vascular segments, a large eccentric catheter for excimer laser coronary angioplasty has been developed. The outer tip diameter is 2.0 mm and incorporates approximately 300 fibers of 50 micron diameter in a monorail- type percutaneous catheter. The basic function of the device is to ablate a coronary atherosclerotic lesion with 308 nm excimer laser pulses, while passing the tip of the catheter through the lesion. By employing multiple passes through the lesion, rotating the catheter 90 degrees after each pass, we expect to create luminal diameters close to 3 mm with this device. Design characteristics, in-vitro testing, and initial clinical experience is presented.
A novel laser catheter design has been utilized to assist in the removal of chronically implanted pacing leads. The catheter, or 'laser sheath,' uses fiber optics to convey pulsed 308 nm light from a CVX-300 XeCl excimer laser to the distal tip of the catheter. As the catheter is threaded over an implanted pacing lead, into the patient's vasculature, lasing action can be used to cut through fibrotic adhesions that typically overgrow the lead, making lead removal difficult. In a randomized clinical trial, greater than 300 patients have been treated with the laser sheath, with no complications secondary to the use of the laser. Leads were totally removed in nearly all laser cases. Design features of the laser sheath that contribute to its clinical success are discussed.
In this paper, we present performance, reliability, and maintainability data for the ELS-4000, a production-worthy, spectrally narrowed KrF excimer laser for wafer steppers. This laser uses the same modular design concept as its predecessor, the CX-2LS. The ELS-4000 exhibits the following specifications: (i) spectral bandwidth (FWHM) less than 2.0 pm; (ii) wavelength stability less than or equal to 0.25 pm; (iii) output power of 4 W at 400 Hz; (iv) pulse-to-pulse energy stability less than or equal to 2.5%; (v) fast and accurate wavelength slewing and locking capability; (vi) small footprint measuring 0.74 m by 1.36 m; (vii) mean productive time between failures exceeding 700 hours; and (viii) design and engineering features, which meet all the safety standards of
the semiconductor industry.
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