Resection of Calcified Aortic Heart Leaflets in Vitro by Q-switched 2 µm Microsecond Laser Radiation

Background: Transcatheter aortic valve implantation (TAVI) can result in paravalvular leakage and stent deformation in the presence of severe calcification. This study was undertaken to determine the efficacy of laser-assisted resection of calcific aortic valve leaflets as a method to minimize the effects of calcium on perivalvular leakage during TAVI.

Methods: A Q-switched Tm:YAG laser emitting at a wavelength of 2.01 μm was used to evaluate the cutting efficiency on highly calcified human aortic leaflets in vitro (N = 10). A pulse energy of 4.3 mJ, a pulse duration of 0.8-1 μs, and a repetition rate of 1 kHz were used. The radiation was transmitted via a 200 µm core diameter quartz fiber. Resection was performed in a fiber-tissue contact mode on water-covered samples in a dish. The remnant particles were analyzed with respect to quantity and size by light microscopy.

Results: A resection rate of 40.4 ± 22.2 mg/min on highly calcified aortic leaflets was achieved. This corresponds to a cutting speed of approximately 1 cm/min; a laser dissection time of 3 min per leaflet is expected. The majority of the remnant particles (85.4%) were <6 μm in diameter, with only 0.1% exceeding 300 μm.

Conclusions: The Q-switched Tm:YAG laser system showed promising results in cutting calcified aortic valves, by transmitting sufficient energy through a small flexible fiber. Catheter-based removal of aortic valve calcification may help to improve TAVI technology.