leadless pacemaker by the European Union. St. Jude Medical had secured the exclusive right to acquire Nanostim with a May 2011 investment in the start-up. St. Jude Medical continued the restructuring it started in 2014 with its consolidation of the company's two operating units—the implantable electronic systems and the cardiovascular and ablation technologies units—into single research and development division. The company also consolidated its worldwide manufacturing and supply chain operations into a second division. In July 2015, the company announced its intention to acquire heart-device manufacturer Thoratec Corporation for $3.4 billion. The acquisition was completed in October 2015. In September 2015, St. Jude Medical announced that Daniel Starks would retire as chairman, president, and chief executive officer. On January 1, 2016, Michael T. Rousseau succeeded Starks as president, CEO and a member of the St. Jude Medical Board of Directors. Starks would remain executive chairman of the board of directors. In late April 2016, Abbott Laboratories announced it would acquire St. Jude Medical for $25 billion ($46.75 in cash & 0.8708 shares of Abbott common stock, equating to an approximate value of $85 per share). On January 5, 2017, Abbott announced that it had completed its $25 billion acquisition of St. Jude Medical. Acquisition history The following is an illustration of the company's major mergers and acquisitions and historical predecessors (this is not a comprehensive list): Operations St. Jude Medical manufactures implantable cardioverter-defibrillators (ICD); pacemakers; electrophysiology catheters; vascular closure products; cardiac mapping and visualization systems; optical coherence tomography (OCT) imaging systems; structural heart repair products; and neurostimulation devices. The company's operations are divided into two divisions: research and development; and manufacturing and supply chain. St. Jude Medical also operates six technology centers located in Brussels, Belgium, Beijing, China, Tokyo, Japan, Austin, Texas, St. Paul, Minnesota and Sylmar, California. These centers offer training to physicians and allow them to simulate patient procedures using St. Jude Medical devices and technologies. Products The company also manufactures implantable cardioverter-defibrillators (ICDs) and implanted cardiac resynchronization devices (CRT-Ds). The ICDs and CRT-Ds use quadripolar lead technology, which utilizes four electrodes on a single lead to pace multiple locations on the left side of the heart. In 2013, the company began marketing the Ilumen Optis device, which is a diagnostic and assessment tool for patients with coronary artery disease. The device uses fractional flow reserve for measuring intra-arterial pressure and optical coherence tomography technology, which allows doctors