Researchers at Ohio State University (OSU, Columbus, USA), Advocate Heart Institute (Naperville, IL, USA), and other institutions conducted a prospective, randomized trial involving 151 patients in 31 hospital-based centers in Germany, Poland, and the USA, to test the remedé system, an implantable transvenous device made by Respicardia (Minnetonka, MN, USA) which stimulates the phrenic nerve to cause diaphragmatic contraction, similar to normal breathing.

 

All study participants underwent device implantation and were randomly assigned to either stimulation or no stimulation (controls) for six months. The primary effectiveness endpoint in the intention-to-treat population was the proportion of patients achieving a 50% or greater apnoea-hypopnoea index (AHI) reduction from baseline, as measured by a full-night polysomnography assessed by masked investigators and compared to the control population. Between six and 12 months of follow-up, all patients received the neurostimulation treatment.

 

The results revealed that at the six-month evaluation, the device reduced CSA events per hour by half or more in 51% of the treatment group; only 11% of controls achieved the same level of reduction. Other important sleep measures, such as the amount of time spent with a low blood oxygen level, were also significantly improved. About a third of the patients in the treatment group reported therapy-related discomfort that was resolved with some further reprogramming of the device. The study was published on September 3, 2016, in The Lancet.

 

“CSA is a serious concern because it affects about a third of people with heart failure and it's known to make the condition worse,” said senior author William Abraham, MD, director of the division of cardiovascular medicine at OSU. “Currently, we don't have good treatments available. Positive airway pressure devices have been used, but many patients don't tolerate them well and a recent study showed them to be harmful. The effects of neurostimulation are clinically relevant, and this could be a promising therapy for those with central sleep apnea.”

 

Unilateral transvenous phrenic nerve stimulation is provided by a neurostimalor implanted in the left pericardiophrenic or right brachiocephalic vein in order to stmulate the adjacent phrenic nerve, resulting in diaphragmatic contractions during sleep. The result is a stabilized gas exchange and a more regular breathing pattern, fewer apneic events, improved oxygen saturation, and increased end-tidal carbon dioxide (CO2), without suppressing the intrinsic drive to breathe in patients with CSA.