St. Jude Medical Inc. is studying the design of a new type of minimally invasive heart valves amid questions over whether the devices can collect clotted blood.

An editorial in the New England Journal of Medicine on Monday declared that more information is urgently needed about the bioprosthetic valves. An article written by 24 physicians in the same publication found that patients in three small studies who took blood-thinning drugs after getting the valves implanted avoided the blood-clot problems, which can reduce the valves ability to efficiently pump blood.

Dr. Gregory Helmer, who directs the transcatheter aortic valve replacement program at the University of Minnesota, said the latest minimally invasive valves will continue to benefit eligible patients, who tend to be among the sickest patients with aortic stenosis, a narrowing of the aortic valve. He questioned the tone of the NEJM editorial’s declaration of urgent need.

“I think that is an overstatement,” Helmer said Monday. “I think more information would be wonderful and we look forward to it further advancing this field of medicine, which continues to advance at a rapid pace. I don’t think there’s any need to panic or have that type of language in there.”

St. Jude agreed with the call for more information. In addition to studying its own unapproved device for minimally invasive aortic valve replacement, called the Portico, it will look at commercially available valves. In the U.S., Edwards Lifesciences and Medtronic are approved to sell such devices.

In June, St. Jude said it detected reduced motion in other valves besides its own.

Until 2011, virtually all patients in the United States who had an artificial heart valve implanted got one via open-chest surgery, which can be too traumatic for older and more frail patients. The new minimally invasive aortic valves, approved only for high-risk patients, allow doctors to place the device inside the heart using a narrow tube snaked through the body’s blood vessels.

More than 200,000 people have had one implanted. Analysts project device companies will sell $4 billion worth of the valves by 2020, as the devices gained acceptance among less-risky patient populations.

The study Monday found that the risk of reduced valve motion appeared common to all bioprosthetic valves, not just the minimally invasive type. Such valves, which are composed of heart tissue taken from animals like pigs and sewn onto a metal frame, were thought to offer an advantage over traditional mechanical artificial valves that require patients to take blood thinning drugs for life. Monday’s study calls that into question.

“I’ve always said that we don’t really know the optimal anti-coagulation therapy for these patients after these valves have been deployed,” Helmer said. “This brings that even further to light.”