| 摘要 |
A cannula includes a tubular body and an endoscope for viewing through a transparent, blunt, tissue-separating tip substantially covering the distal end of the body. Endoscopic viewing through the tip is enhanced by inner walls that taper to a cusp adjacent the blunt tip in order to reduce visual distortion. Alternatively, a cannula includes a dissection probe and a removable or deflectable tip for exposing the probe and endoscope to facilitate viewing and the dissection of connective tissue and lateral vessels along the dissected cavity. Methods of using such cannulas produce an elongated cavity along the course of a vessel for subsequent harvesting or other treatment of the isolated vessel. Lateral branch vessels of a main vessel to be harvested are doubly clipped or otherwise doubly occluded, and then severed to isolate the main vessel for use, for example, in revascularizing the coronary artery.
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