Acting Allegheny County Allegheny County Sheriff William P. Mullen was in critical but stable condition yesterday at Mercy Hospital after emergency heart surgery.

Sheriff Mullen was stricken with a heart attack Tuesday after playing basketball at a gym on the South Side at about 7:30 p.m.

According to a statement from the hospital, "Sheriff Mullen is conscious and resting with his family at his side."

Acting Chief Deputy Sheriff Joseph Rizzo said Sheriff Mullen was expected to remain hospitalized for seven to 10 days. He said the acting sheriff suffered no heart damage during the attack and "the doctors expect a full and complete recovery."

Sheriff Mullen moved up to that position Nov. 1 after former Sheriff Pete Defazio retired. The department was roiled by a five-year investigation that ended last year with the plea by Mr. DeFazio in U.S. District Court to a single count of macing. The term macing refers to coercing public employees to contribute to a political campaign.

Deputy Sheriff Rizzo said Sheriff Mullen had taken a seat on the bench after playing a basketball game when he collapsed. Cardiopulmonary resuscitation was provided by two men who had served with him on the Pittsburgh Bureau of Police.

His promotion came automatically from a provision in the second-class county code that states that if the sheriff does not complete his term, the chief deputy sheriff becomes the acting sheriff. Sheriff Mullen had been the chief deputy sheriff since April.

Deputy Sheriff Rizzo, who is running the office, said the Sheriff's Department has received "a lot of great support from the county executive's office" since the acting sheriff's heart attack. He said he expects to be in daily contact with Sheriff Mullen as early as next week.

"He's a worker," Deputy Sheriff Rizzo said about Sheriff Mullen.

County Solicitor Michael Wojcik said it is up to the governor to appoint a new sheriff to take office for the rest of this year until a new sheriff can be elected.

This year, the county also is planning a referendum for the May primary to eliminate the elected office and replace it with an appointed sheriff. If that is approved by County Council for the ballot, the candidates running in the primary would be in the position of running for an office that may be abolished before they can take charge.

Sheriff Mullen, for instance, is on record as saying he plans to run for the Democratic nomination, but also supports abolishing the elected position.

Yesterday, during a news conference about proposed transit cuts, county Chief Executive Dan Onorato supported keeping Sheriff Mullen in his job through the end of the year.

Mr. Wocjik said it is the administration's hope that the governor acts quickly to name a sheriff and that the name he chooses is William P. Mullen Jr.