Oropharynx-Brainstem-Heart Connection: A Controlled Clinical Trial to Assess Atrial Fibrillation Attenuation in Patients Treated With Oral Appliance Therapy

Atrial fibrillation (AF) is highly prevalent in the U.S. and possesses a greater risk in patients with sleep disordered breathing (SDB) versus patients without SDB. AF recurrence after catheter ablation is associated with 25% increased risk in patients with obstructive sleep apnea (OSA). One hypothesis suggests that the repeated hypoxic episodes time-linked to OSA and central sleep apnea may act as chemo-reflex triggers that enhances brainstem sympathetic activity in conjunction with responses to OSA-event hypoxia. This hypothesis is believed to induce tachycardia and cardiovascular stress. In an animal model, episodes of hypoxia were shown to induce pulmonary vein burst firing and reduction of the negative tracheal pressure promptly restored normal sinus rhythm. The Trigemino-cardiac reflex hypothesis implicates chemo- and mechanoreceptors in the oronasal cavity that provides signaling to the reticular formation via the mesencephalic nucleus of the trigeminal nerve and serves to control breathing, cardiac function, blood pH (acidity), amongst other body functions.

The sympathetic system in patients with OSA syndrome is considered to be chronically hypersensitized. A hyperarousal state suggests AF patients with OSA would tend to have AF occur more frequently in conjunction with apnea hypopnea events. An increase in autonomic sympathetic cardiac dominance with a withdrawal of cardiac parasympathetic control could easily be driven by mechanoreceptors in the oropharynx upon airway narrowing and present as decreased heart rate variability. Considering that the upper airway is often the site of greatest airflow restriction (i.e. snoring), a potential sudden rise in autonomic sympathetic nerve activity in sensory afferent fibers from the oropharynx should be the first to communicate the airflow reduction to brainstem. This theory is supported by the investigators' preliminary data and those in other reports. Oral appliance (OA) therapy that prevents snoring in conjunction with a mouth shield should simultaneously facilitate an open airway and prevent mouth breathing. The combination effect is expected to decrease vagus nerve motor efferent activity to the esophagus, facilitate nasal breathing, reduce sympathetic tone, promote stable sleep and increase HRV(heart rate variability). In patients with AF, the MyTAP + MS intervention is likely to also facilitate putatively effective medical therapies, reduce noxious AF triggers, and maintain normal oral bacterial flora levels and cardiac functioning.