Image: The Remedé neurostimulator with the stimulation lead in the left pericardiophrenic vein and the sensing lead in the azygos vein (Photo courtesy of Respicardia).
An implantable neurostimulator indirectly stimulates the phrenic nerve, significantly improving central sleep apnea (CSA) symptoms.
The Respicardia (Minnetonka, MN, USA) Remedē System provides transvenous phrenic nerve stimulation via the left pericardiophrenic or right brachiocephalic vein to the adjacent phrenic nerve, resulting in stimulated diaphragmatic contractions during sleep. As a result, a stabilized gas exchange and improved breathing pattern are established, with fewer apneic events, improved oxygen saturation, and increased end-tidal carbon dioxide. An added benefit is that the system does not suppress the intrinsic drive to breathe in patients with CSA.
The system includes a battery-powered pulse generator implanted under the skin in the upper chest and thin transvenous wire leads. It is programmed using an external system programmer and programming wand. The system has two therapy approaches; an asynchronous mode that generates pulses at a fixed rate, and a synchronous mode that delivers a pulse only when a pause in breathing is detected. System safeguards ensure that therapy is only delivered during sleep, and that the system only turns on when the patient is inactive and lying down.
In a study involving 141 CSA patients, the apnea hypopnea index (AHI), a measure of the frequency and severity of apnea episodes, was reduced by 50% or more in a majority of patients with an active Remedē System implanted. The most common adverse events were concomitant device interaction, implant site infection, swelling, local tissue damage, or pocket erosion. The Remedē System is not intended for use in patients with obstructive sleep apnea (OSA), a condition in which the patient attempts to breathe, but the upper airway is partially or completely blocked.
“This implantable device offers patients another treatment option for central sleep apnea,” said Tina Kiang, PhD, of the U.S. Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH). “Patients should speak with their health care providers about the benefits and risks of this new treatment compared to other available treatments.”
In CSA the respiratory control centers in the brain are dysfunctional during sleep, failing to provide the signal to inhale, thus leading the individual to miss several cycles of breath and an increase in carbon dioxide levels. Typically, episodes last for 10-30 seconds and can be intermittent in nature. Potential causes of CSA include heart problems, brain disorders, medications, other substances, and idiopathic causes.