A cannula adapted for antegrade administration of cardioplegic solutions during surgical procedures on the heart. A normal physiological condition such as "patent" (meaning open) "antegrade flow" (meaning flowing forward) of the vertebral arteries" is not dangerous.This page provides information on the types of patents and types of patent applications, and the examination process. A stepbystep overview of a patent application and maintenance process. The five stages of a patent process. There are several important steps to draft, file, and prosecute a patent in Texas. Enter the city or county in Texas for which you are trying to determine venue. Patent Office staff offer a set of steps for an inventor to work through. Pulsatile flow loop. Persistent antegrade LIMA flow.