He worked as a consultant in the Ministry of Education and Church Affairs and at a teachers' college before being assisting chief executive at NKI-skolen.
During Korvald's Cabinet from 1972 to 1973, he was a State Secretary, first in the Ministry of Local Government and Labour, then in the Office of the Prime Minister.
After that he held another political position, secretary-general of the Christian Democratic Party, before he was director of enterprise in Vestfold County Municipality.
The chief executive Steinar Stokke had to step down from several hospital boards in May 2003 because of a flawed project where patient diagnoses was to be coded in different ways to be eligible for public funding.
Arntsen subsequently had to resign, but in response, the Minister of Health Dagfinn Høybråten promptly relieved the entire board of their positions.