Arihara underwent surgery Thursday to remove an aneurysm and repair the artery in his right shoulder, Kennedi Landry of MLB.com reports.
The procedure puts Arihara's availability for the remainder of the season in jeopardy, though the Rangers aren't yet ready to rule out the right-hander from returning to action in August or September. He'll spend the next month resting up before the Rangers re-evaluate him in late June, at which time he could be cleared to begin a throwing program.