Feasibility Study of Extracorporeal Shock Wave Lithotripsy for Chronic Total Occlusion Therapy

Abstract

Recently, due to a lack of exercise and aging, cardiovascular disease has become a major cause of death worldwide. Drug therapy and surgical operation have been widely used to treat cardiovascular disease. However, the treatment of chronic total occlusions (CTOs) through clinical operation still remains a considerable challenge, as CTOs have stiff proximal fibrous caps on their ends, which can be a serious barrier for a conventional operation using guide wires or biomedical devices. Through the analysis of the composition and physical properties of CTOs, we synthesized an artificial CTO composition consisting of collagen, blood, CaCO3, and levo-polylactic acid polymer. The artificial CTO composition was inserted into an arterial segment of swine, and a final CTO artery model was obtained. For the feasibility test of an extracorporeal shock wave lithotripsy (ESWL) device for CTO therapy, we adopted ESWL equipment with a C-arm X-ray fluoroscope. Through the feasibility tests, the optimal parameters of the ESWL equipment were found: an energy level of 4 (16.7–17.2 kV) and a total of 1000 shock waves. A tunneling efficiency of 85 % was achieved with the optimal parameters. We also tested the tunneling efficiency according to increased tissue thickness with the optimal parameters; the tunneling efficiency was reduced when the tissue thickness was increased, but the tunneling efficiency remained at 62 % for a tissue thickness of 3 cm. In addition, the final remaining clot ranged in size from 3 to 183 μm, which was observed using a Nikon Ti-U microscope and analyzed using ImageJ. The safety of ESWL treatment was also confirmed through pathological analysis. Consequently, we expect that ESWL might become an effective therapeutic method for the tunneling of CTO.