Robert Kohler

Removal of Calcified Plaque Utilizing Orbital Atherectomy

Arterial disease occurs when plaque builds up in the arteries and limits flow of oxygen-rich blood to organs and other parts of the body reducing organ function. Atherectomy is a mechanical process in which plaque is removed from artery walls or modified to change vessel compliance. Various types of atherectomy systems exist to remove or modify plaque depending on plaque morphology. Orbital atherectomy (Diamondback 360® Orbital Atherectomy System) is a sanding process utilizing a diamond abrasive crown mounted eccentrically to a flexible drive shaft.The effects of rotational speed, crown size, centrifugal forces and run time were evaluated. Finite element modeling and bench testing using carbon as a calcified plaque surrogate material were used.The crown-simulated vessel wall force was calculated using a finite element model that included a rigid vessel wall and a rotating crown. Results show a small force when the crown begins to rotate at lower speeds, that increases to a peak force at maximum speed, and decreases as the orbit diameter increases with material removal.A design of experiments plan was created and used to quantify the effects of crown size rotation speed and number of treatment passes on lumen diameter. Increasing the crown diameter increased lumen diameter nonlinearly at an increasing rate with crown rotation speed in the carbon model.Scanning Electron Microscopy (SEM) analysis of the particulate material removed in the bench test demonstrated brittle fracture as the mode of material removal of the carbon surrogate.Copyright

Coronary artery rotation in native and stented porcine coronary arteries

Coronary arteries are exposed to several complex biomechanical forces during the cardiac cycle. These biomechanical forces potentially contribute to both native coronary artery disease, development of atherosclerosis and eventual stent failure. The aim of the present study was to characterize and define coronary artery axial rotation and the effect of stent implantation on this biomechanical factor.