Indianapolis ? Boston Scientific Corp. made an unexpected, $25 billion takeover offer Monday for the troubled medical device maker Guidant Corp., more than $3 billion more than what Johnson & Johnson agreed to pay for Guidant last month.

Boston Scientific, which makes heart devices, offered in a letter to Guidant’s chairman to pay a combination of cash and stock worth about $72 per Guidant share. It said that is nearly 14 percent above Friday’s value of J&J’s revised cash-and-stock deal for Guidant.

The offer comes nearly a year after J&J said it would buy the Indianapolis medical-device maker for $25.4 billion. But J&J cut its offer by nearly $4 billion after a series of product recalls by Guidant, and Guidant management accepted the lower price last month.

Boston Scientific executives said the prospect of entering the lucrative market for implantable pacemakers and defibrillators by purchasing Guidant outweighs the legal risks posed by Guidant’s recent problems.