Seminar - A new device for crossing chronic total occlusions by Professor Martin Brouillette
Date: 15 December 2015 (Tuesday)
Time: 11:00 am – 12:00 pm
Venue: EF305, The Hong Kong Polytechnic University
Cardiovascular disease is the leading cause of death worldwide. This disease includes chronic total occlusions (CTOs), which are complete blockages of an artery. Unlike partial occlusions, CTOs are difficult to cross percutaneously using conventional guidewire (thin and flexible wires) techniques because of the fibrotic and calcified nature of the blockage.
We report on the design and testing of a new minimally-invasive device used to cross CTOs in the coronary and peripheral vasculature. The device is based on a novel high-power ultrasound generator which exploits inverse dispersion in long solid waveguides to amplify the signal of broadband piezoelectric ultrasound transducers to produce high-amplitude (~500 Bars) and short duration (~1 microsecond) pressure pulses. These pulses are then propagated into small (~0.35 mm) non-dispersive waveguides, which have the same dimensions and properties as conventional cardiology guidewires, for percutaneous introduction into the vascular system. The distal tip of the non-dispersive waveguide is then placed in contact with the occlusion where the arrival of the mechanical pulses locally erodes the hard calcified components of the CTO, enabling the waveguide to progress across the lesion.
This device was extensively tested on the bench using a variety of CTO surrogates such as egg shells, plasters as well as calcified plaques obtained from leg amputations. Also, the safety of this method was assessed by subjecting live ex-vivo pig arteries to the tip of the waveguide for 3 minutes under full power. State-of-the-art microscopy techniques have shown that epithelial cell viability was greater than 80% following exposure, which is comparable to that following the simple introduction of a guidewire. Finally, ex-vivo CTO segments, obtained from leg amputations, were successfully crossed on the bench after unsuccessful attempt with commercial equipment.
Martin Brouillette holds a B. Eng. from McGill University and both a Master's and a Doctorate in Ae