(CNN) Baquer Namazi, an Iranian-American who has been imprisoned in Iran since February 2016, has been discharged from an Iranian hospital and granted a four-day leave by the Iranian government, according to his family and the State Department.

Namazi is the father of American businessman Siamak Namazi, who has been detained in Iran since October 2015.

Namazi's family said the 81-year-old had been rushed to the hospital on January 15 after a severe drop in his blood pressure, an irregular heartbeat, serious depletion of energy and coloring turning white. This was the fourth time, the family said, he had been transferred to a hospital in the last year. He underwent emergency heart surgery to install a pacemaker.

Namazi has been held in Iran's notorious Evin prison when not in the hospital. His family has said imprisonment there would exacerbate the condition of his health.

Babak Namazi, Baquer's son, issued a statement expressing gratitude for the temporary leave and asking for a permanent release.

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