A state decision on whether to allow hospitals to perform elective angioplasties without having a backup cardiac surgery unit onsite will be decided after a series of public hearings, state Health Commissioner Mary E. O'Dowd said on Tuesday. Angioplasty is a procedure performed by specially trained cardiologists, typically to open a blocked or narrowed artery. With cardiac surgery, in contrast, the heart is operated on directly. The State Health Planning Board will hold a series of regional hearings to gather information before the state issues new angioplasty regulations, O'Dowd said. The subject has sharply divided hospitals over the past decade.