The PFO (patent foramen ovale) closure market has certainly traveled a long and twisted road over the years. And the journey isn't over yet. Although some large companies have pulled back on their US commercialization efforts or decided to exit the field entirely, othrs continue to stick it out, hoping the eventual opportunity will far outweigh the risks and costs involved. In Europe, where percutaneous PFO closure following stroke/TIA is more widely accepted and performed, there are nine CE marked PFO closure devices available from eight different manufacturers, with two more devices expected to be added to the mix in the near future. But despite widespread European acceptance, manufacturers have so far failed to achieve the ultimate goal: US regulatory approval.

The seeds planted in neurostimulation ventures over the past 10 years have produced more disappointments than results, but the fallow period is over. The Food & Drug Administration recently cleared Neuronetics to begin selling its NeuroStar TMS as a treatment for people who haven't responded to a drug regimen taken during their current episode of depression. This is good news for scores of venture-backed neurostimulation companies, although Neuronetics is somewhat unique. It is developing a non-invasive device that delivers magnetic, rather than electrical pulses.

For Northstar Neuroscience, which is exploring new approaches for neurostimulation devices, the decision to take the money and run when the device IPO window was open in 2006 has meant the difference between survival or closing up shop. The FDA's recent approval of the company's second study of its Renova cortical stimulation device for the treatment of major depressive disorder is one sign that reports of Northstar's demise may, have been premature. The company's second chance can largely be attributed to the fact that it flew in the face of conventional wisdom that held that it was too early for the company to go public in 2006.