St. Jude Medical Inc. on Monday announced the acquisition of Nano­stim Inc., giving the Little Canada-based medical technology company the world's first commercially available "leadless" pacemaker.

The deal with the small California-based company has been in the works for a couple of years. Buying Nanostim gives St. Jude's inventory of heart rhythm products a wireless pacemaker about the size of a AAA battery. St. Jude will soon put the device on the market in Europe and it has also received approval from the U.S. Food and Drug Administration to begin evaluating it in clinical trials in the United States.

Much of the buzz around the pacemaker has to do with its size, and the fact that it does not connect to the heart with wires — called leads. Conventional pacemakers were once the size of a hockey puck and now are comparable to three stacked 50-cent pieces. They deliver an electric pulse over leads that are snaked through veins into the heart. Leads, however, are considered the weak link of pacemakers and implanted defibrillators. Their thin wires can sometimes fracture and fail as the human heart beats more than 115,000 times a day.

The company announced that the device has received CE Mark approval and will be commercially available soon in select European markets. St. Jude officials would not comment on when they believe the device might be available in the United States. That probably would not happen for a least a few more years.

St. Jude has had its problems with leads, having to pull its Riata defibrillator lead from the U.S. market because of problems with inner wires coming through outer insulation. Its QuickSite and QuickFlex pacemaker leads were also pulled for the same reasons.

Besides avoiding lead issues, St. Jude said the new device will reduce complications and improve patient comfort. Cardiologists must create a "pocket" just beneath the skin of the patient's chest to hold a traditional pacemaker generator. The Nano­stim pacemaker, which is less than 10 percent the size of a traditional pacemaker, does not need a "pocket." Doctors will be able to deliver the device to the interior of the heart by steering a catheter up through a vein in the leg. It will be attached to the interior wall of the heart.

"The Nanostim leadless pacemaker represents one of the most important advances in the history of pacing technology," said Dr. Eric Fain, president of St. Jude's implantable electronic systems division.

Said Dr. Johannes Sperzel of the Kerckhoff Klinik in Bad Nauheim, Germany: "This revolutionary technology offers my patients a safe, minimally invasive option for pacemaker delivery that eliminates leads and surgical pockets. This is the future of cardiac pacing."

It could also become an attractive alternative for younger pacemaker patients, who bemoan the visible lump and scar on their chest from a traditional pacemaker. In addition, it would eliminate the need to remove failed pacemaker leads — a sometimes risky procedure — from younger patients who will need a device for decades to come.

Dr. Mark Carlson, chief medical officer at St. Jude, said the Nanostim pacemaker "could be perfect for younger patients. Young patients grow taller and the leads that connect a pacemaker to the heart will not grow," he said. "Doctors put in slack, but they cannot do enough of that."

Carlson said the device has an average battery life of nine years and is designed to be retrievable from the heart when it needs to be replaced. Pacemakers must be replaced when their battery wears out. A recent study shows the overall performance of the miniature pacemaker is comparable to conventionally sized devices, St. Jude said.

Cardiac pacemakers are used to treat patients whose hearts beat too slowly. Carlson acknowledged that the Nano­stim device is not appropriate for some pacemaker patients. While it can automatically adjust its pacing to adapt to a patient's activity levels, it is designed for patients who need only one chamber — the right ventricle — of their heart paced. Many patients need what is called dual-chamber pacing to put their heart into the most efficient rhythm.

"This is the first step," Carlson said. "But we certainly anticipate developing this technology not just for single-chamber but dual-chamber pacing."

The terms of the deal

The acquisition announced Monday closes a series of agreements made between St. Jude and privately held Nano­stim in May 2011. St. Jude Medical paid $123.5 million to Nanostim shareholders — with another $65 million in cash to come, based on a number of milestones. St. Jude officials said that except for acquisition-related expenses, the deal does not affect the company's 2013 earnings per share outlook.

St. Jude Medical, with about 16,000 employees worldwide and 2,500 workers in Minnesota, said Nanostim and its 45 employees will become a part of the company's implantable electronic systems division.

St. Jude is the first of the big three medical device firms with local ties to bring a leadless pacemaker to market, but Medtronic and Boston Scientific are developing similar devices, said analyst Larry Biegelsen of Wells Fargo. In a May 13 note to investors, he said data regarding the device "appears mostly positive."

Jeff Windau, an analyst with Edward Jones, said St. Jude has a chance to gain customers.

"It is definitely the next step in innovation. When you think of what has been a key source of problems in the area, it has been leads and problems with the leads — fractures, removals," he said. "It just opens more doors for patients, maybe other patients for whom [leads] might be a problem."

Still, he cautioned, much remains to be learned once U.S. clinical trials start. "As with any new device, the trials will be watched carefully over time to see if there are unintended consequences and problems."