Boston Scientific has responded swiftly to Johnson & Johnson’s raised bid for medical device maker Guidant by sweetening its own offer by a dollar a share.

In a press release, Boston Scientific also said that the $73-a-share offer was good only until 4 o’clock this afternoon, piling the pressure on Guidant’s management to recommend the bid to its shareholders.

J&J hiked its own offer to a little over $68 on Wednesday, and in a joint statement with Guidant said the bid had been accepted and would be recommended to Guidant investors at a meeting on January 31. But this united front was undermined almost immediately after one of Guidant’s shareholders, Elliott Associates/Elliott International, said they would oppose any deal from J&J under $71 a share even before Boston Scientific’s improved offer was tabled.

As it stands, Boston Scientific’s offer values Guidant at around $26 billion, compared to J&J’s $23.2 billion proposal.

Elliott, which holds around 3 million Guidant shares, also said it was still concerned about the antitrust risks associated with a Boston Scientific acquisition, even though the latter firm has already agreed to divest Guidant’s cardiovascular stent business – the most likely area of concern – to Abbott Laboratories for $4 billion.

Johnson & Johnson originally offered $25.4 billion for Guidant in December 2004, but lowered the amount to $21.5 billion 11 months later because of a major product recall at Guidant, as well as regulatory investigations that it said had affected the business's value. Boston Scientific made its $25 billion bid in December, and tabled a formal offer January 8.

Both companies want Guidant to grab a slice of the fast-growing $10 billion market for pacemakers and implantable cardiovascular defibrillators (ICDs). Guidant is placed second in this market, behind Medtronic and ahead of St Jude Medical, but is gearing up to launch a new range of cardiac rhythm management (CRM) systems, including wireless versions, that are tipped to be big sellers.