Transvenous Phrenic Nerve Stimulation for Central Sleep Apnea

Central sleep apnea (CSA) occurs when there is a recurrent temporary failure of the pontomedullary breathing pacemaker and subsequent cessation of breathing during sleep. The pathophysiological changes of low cardiac output states are the most common causes of CSA. Thus, CSA occurs most frequently in patients with underlying cardiovascular disease and specifically heart failure (HF). However, cessation of inspiratory effort is also observed in other physiologic and pathophysiologic states such as high-altitude induced periodic breathing, narcotic-induced CSA, and idiopathic CSA, along with any processes that may compress the brainstem. CSA is associated with immediate negative consequences, including intermittent hypoxia and sympathetic activation. Several studies have reported an association between CSA and worsened mortality in HF patients. Therefore, the treatment of CSA has been considered part of standard care, especially in patients with HF. In these patients, treatment of CSA can improve sympathetic activation, quality of life and decrease arrhythmias. Previously, the mainstay of treatment for CSA was continuous positive airway pressure (CPAP) therapy and then, as technology evolved, Adaptive Servo Ventilation (ASV). Recent data have suggested increased mortality in patients with HF with reduced ejection fraction (HFrEF) treated with ASV for CSA with EF <45, excluding this otherwise efficacious modality from usage in the majority of patients with CSA. Upon this background, the recent introduction of a novel therapeutic modality, transvenous phrenic nerve stimulation (TPNS), provides a valid treatment option that should be considered in all patients with CSA. In this chapter, we will introduce this treatment modality to the reader and attempt to provide a comprehensive overview of its operation, efficacy data, and application to the treatment of patients with CSA.