In the immediate aftermath of the Obamacare rollout, pharma and healthcare M&A fell. Now, however, it's back up, on deals like Monday morning's Covidien - Medtronic announcement, a merger valued at $43 billion. While some deals in the healthcare industry are being guided by synergies, other, like Monday's MergerTalk deal, are being guided by strategy. Medtronic needs to relocate its Minnesota tax base to Ireland, where Covidien is based, in order to save on a hefty U.S. tax bill. Medtronic isn't the only one: Pfizer attempted to acquire AstraZeneca, for the same reasons. The Deal's Jon Marino and Sarah Pringle have details from Wall Street.