The challenges of developing the LimFlow System for Transcatheter Arterialization of Deep Veins (TADV) went beyond engineering and anatomical obstacles.

One of the biggest hurdles was downright emotional, LimFlow leaders said in an interview with Medical Design & Outsourcing before they sold their company to Inari Medical.

Artery-to-vein crossing is key to LimFlow’s unique FDA-approved system for chronic limb-threatening ischemia (CLTI) patients who have no other option than lower limb amputation.

To restore blood flow to an ischemic foot, the TADV system uses LimFlow’s ARC arterial catheter’s needle inside the tibial artery to puncture the adjacent tibal vein at the precise location of Limflow’s V-Ceiver venous catheter. A guidewire between the two catheters allows a physician to insert a self-expanding nitinol crossing stent to route the blood from the blocked artery to the vein, restoring oxygenation to the foot. (Read more about how the entire process works in this earlier post.)

To line up the two catheters for the needle to puncture the artery and vein in the right places, LimFlow started out with a non-imaging ultrasound approach with one catheter emitting a signal and the other receiving, CEO Dan Rose said.

“This was really cool technology, a very clear differentiation from what’s available, but what we figured out was that we could probably develop something that was very elegant, very straightforward, very usable with no electronics, nothing plugged into the wall,” he said.

Instead, they designed the V-Ceiver catheter to expand the vein to present a larger target. Radiopaque markers in the catheter help the physician visualize the vein with fluoroscopy, and the catheter’s nitinol mesh captures the wire once it has crossed from the artery into the vein.

“We got rid of a lot of cost and a lot of complication and just went simple,” Rose said. “It dropped crossing times by an hour, believe it or not.”

It wasn’t an easy choice — or cheap. The company had already invested in developing, validating and certifying the technology for the system’s CE mark in Europe.

“It means shelving a lot of IP, it means shelving a lot of investment, going to your board and saying, ‘Hey, wait a minute. We did that, and now we think we can do it more easily,'” Rose said. “But the fact is, if you think about the way technology works, you can either innovate ahead of what may be your competition and make it simpler and easier, or you can wait for them to force you to do it.”

The move away from ultrasound meant turning their back on the technology that they had worked with since the company launched in 2012, a hurdle that was more than just technical.

“We had to build this ultrasound system, validate it, and then we kind of threw all that away and transitioned to something much more usable,” said John Weaver, an engineer by training who serves as LimFlow’s global marketing director. “Not only do we have to overcome those hurdles initially, but then we had to overcome this emotional tie to it and adopt something that’s easier and better for the procedure and better for the therapy.”

Looking back, it was a tough call, but the right call, Rose and Weaver said.

“You have to be bold sometimes and say, ‘Maybe we’re overthinking it and over-engineering,'” Rose said.

This post was originally published on Sept. 29, 2023, and updated after Inari purchased LimFlow in November 2023.