Figure 4: Modification of Kiray and Iimura’s classification system. Type 1 valve - within 20 mm of another central valve, with no intermediate branches; Type 2 valve - between two branches, closer to the peripheral branch, and within 25 mm of that peripheral branch.; Type 3 valve - between two branches, closer to the central branch, and within 15 mm of that central branch; Type 4 valve was defined as having no branches or other valves within (+/−) 25 mm of the valve.