Richard Lord had congestive heart failure so advanced that he’d have shortness of breath from ­sitting on the couch or laying in bed.

Doctors said his weakened heart would only keep him alive for another six months. Yet at 73, the retired banker in Augusta, Minn., was too old for a heart transplant.

On June 9, he became the first person in Minnesota to get a HeartMate 3, a third-generation implanted medical device that continuously pumps the oxygenated blood that his heart couldn’t.

“Quite frankly, I feel good. I’m at 70 percent or 80 percent,” Lord said. “So far, the HeartMate 3 is performing as they had forecast.”

St. Jude Medical is banking on a similarly positive forecast. The company announced plans last week to buy HeartMate’s ­manufacturer, Thoratec Corp., in a $3.4 billion deal that would be St. Jude’s biggest corporate acquisition ever. Data from Thoratec’s European clinical trial of the heart pump have not been released, but St. Jude officials have seen it.

Little Canada-based St. Jude already makes the CardioMEMS device to monitor early heart-failure, and pacemakers and defibrillators to restore a normal heart beat. Circulatory support devices like the HeartMate line mechanically pump blood when the heart can no longer do the job even with drugs, lifestyle changes and heart-rhythm devices.

“The idea that St. Jude is going to have not only pacemakers and these CardioMEMS devices, but also have mechanical circulatory support, I think for them is making them try to be a totally full-service heart-failure device company,” said Dr. Rebecca Cogswell, a cardiologist at the University of Minnesota Medical Center and a principal investigator for the HeartMate 3 trial.

The deal to buy the California-based heart pump company is slated to close by the end of the year. The definitive agreement between the two companies says Thoratec will actively solicit competing proposals through Aug. 20, but it’s not clear that any other device company would put forward a richer offer than St. Jude’s bid of $63.50 per share.

“We don’t believe that another bidder will emerge,” J.P. Morgan Securities analyst Michael Weinstein wrote in a note to investors Thursday. “The financial returns from the deal are relatively modest and we believe that another party would have a difficult time justifying a meaningful premium to St. Jude’s $63.50 offer.”

Heart pumps are reserved for the sickest heart-failure patients, but their high price tags may make up for lower procedure volumes. Medicare pays an average of $149,000 for internal LVAD implantation, and federal officials recently announced they may raise it to $154,000 in 2016.

Thoratec controls 60 percent of the $750 million market for mechanical circulatory support pumps, and St. Jude CEO Dan Starks told investors that 80 percent of Thoratec’s sales still take place in the United States. He also noted that the company is working to commercialize a tiny new heart pump that can fit inside a blood vessel during high-risk heart procedures.

Thoratec has approval from the Food and Drug Administration to sell its earlier-generation HeartMate II pump for two groups of advanced-stage heart-failure patients: those who need a temporary solution until heart transplant, as well as a growing number of patients like Lord, who will use a heart pump as a long-term “destination” therapy.

The device came with risks for developing blood clots and strokes, which caused Thoratec to lose market share to competitors. In published letters, other physicians defended the device’s long term safety and said variables in the use of anti-clotting drugs could explain unexpectedly high rates of blood clots in some patient groups.

Now Thoratec is testing its new HeartMate 3. Starks told investors Wednesday that he got to see the early data on HeartMate 3 performance before making the offer to acquire the company, though he could not reveal what the data say.

“One could certainly surmise that, given our enthusiasm for combining these two companies, that we are very satisfied with what we found on a confidential basis with respect to product pipeline and clinical data,” Starks said.