DIAMondback Atherectomy With OCT Visualization for Calcified PAD Lesions (DIAMOCT-PAD Study).

OBJECTIVE: In this study, we aimed to describe the immediate and long-term vascular effects of OAS in patients with peripheral arterial disease (PAD) and moderate to severely calcified lesions. BACKGROUND: Debulking the calcified atherosclerotic plaque with the orbital atherectomy system (OAS) can potentially enhance vessel compliance and increase the chance of reaching a desirable angioplasty result. METHODS: A total of 7 patients were evaluated both at baseline and at 6-month follow-up. Following a diagnostic peripheral angiogram, patients with significant SFA disease had a baseline intravascular optical coherence tomography (IV-OCT) and the lesion was treated with OAS. Repeat IV-OCT was performed after atherectomy and after drug-coated balloon, if used. Patients were also evaluated with angiography and IV-OCT imaging at their 6-month follow-up. RESULTS: The majority of tissue removed was fibrous tissue. During follow-up, luminal volume increased for 4 of the 7 patients from baseline to 6-month follow-up and decreased in 3 patients. On average there was a 6% increase of luminal volume (P<.01 compared with baseline). A recent virtual histology algorithm was used for automatic classification of IV-OCT images unaided by any reader. The algorithm used convolutional neural networks to identify regions as either calcium, fibrous, or lipid plaque, and it agreed with an expert reader 82% of the time. CONCLUSION: To the best of our knowledge, the current report is the first to describe vascular effects of OAS in medial calcified lesions immediately after and at follow-up using IV-OCT in patients with severe PAD.

Virtual Histology Optical Coherence Tomography Imaging of Orbital Rotational Atherectomy for Calcified Peripheral Arterial Disease.

In order to assess the vascular effects of rotational orbital atherectomy, we performed intravascular imaging with virtual histology intravascular optical coherence tomography in a 72-year-old man with critical limb ischemia of the right lower extremity.

Biophysical mechanisms of transient optical stimulation of peripheral nerve.

A new method for in vivo neural activation using low-intensity, pulsed infrared light exhibits advantages over standard electrical means by providing contact-free, spatially selective, artifact-free stimulation. Here we investigate the biophysical mechanism underlying this phenomenon by careful examination of possible photobiological effects after absorption-driven light-tissue interaction. The rat sciatic nerve preparation was stimulated in vivo with a Holmium:yttrium aluminum garnet laser (2.12 microm), free electron laser (2.1 microm), alexandrite laser (750 nm), and prototype solid-state laser nerve stimulator (1.87 microm). We systematically determined relative contributions from a list of plausible interaction types resulting in optical stimulation, including thermal, pressure, electric field, and photochemical effects. Collectively, the results support our hypothesis that direct neural activation with pulsed laser light is induced by a thermal transient. We then present data that characterize and quantify the spatial and temporal nature of this required temperature rise, including a measured surface temperature change required for stimulation of the peripheral nerve (6 degrees C-10 degrees C). This interaction is a photothermal effect from moderate, transient tissue heating, a temporally and spatially mediated temperature gradient at the axon level (3.8 degrees C-6.4 degrees C), resulting in direct or indirect activation of transmembrane ion channels causing action potential generation.