March 2026 issue, BioElectRx Business Report
March 31, 2026 | Central sleep apnea is a complex condition frequently seen in patients with heart failure or atrial fibrillation. Unlike the physical blockage seen in obstructive apnea, CSA is driven by sympathetic hyperactivity and chemoreceptor hypersensitivity. This creates unstable respiratory control, leading to repetitive breathing pauses that cause hypoxia, oxidative stress, and chronic insomnia.
While CPAP machines are highly effective for obstructive sleep apnea, they generally fail to address the underlying mechanisms of CSA.
To address this unmet medical need, Respicardia developed the remedē system, a transvenous phrenic nerve stimulation therapy. Their journey to market required a total of $153 million raised across four funding rounds between 2006 and 2017. The FDA granted the PMA in October 2017, following a pivotal trial involving 151 patients across 31 sites.
In 2021, shortly after the U.S. market launch, Respicardia was acquired by Zoll Medical (a subsidiary of Asahi Kasei), which now leads commercialization efforts. The remedē TPNS system utilizes a novel neuromodulation technique. Unlike traditional diaphragm pacing, which requires invasive surgery and general anesthesia to implant leads, the TPNS system is implanted via a minimally invasive outpatient procedure. The procedure is performed under sedation by a cardiac electrophysiologist rather than a surgeon. The TPNS system uses transvenous leads inserted through the pericardiophrenic vein to target the phrenic nerve. While stimulation of either the left or right nerve is effective, the left phrenic nerve is often preferred. Because the vein runs closer to the nerve on the left side, the stimulation requires lower amplitude, pulse width, and frequency settings (2 mA, 150 µsec, 20 Hz) compared with those for the right phrenic nerve (2 mA, 300 µsec, 40 Hz).
TPNS leads are notably smaller than cardiac leads: left lead is 1.2 mm and right is 1.6 mm, compared to the 2.2-2.7 mm cardiac transvenous leads used in implantable cardioverter-defibrillators for stimulating the myocardium and in Cardionomic’s implantable pulmonary artery catheter with stent-based electrode for cardiac pulmonary nerve stimulation. Similarly small diameter (1.3 mm) is available in Synchron’s Stentrode, but that lead is designed for neural recording rather than stimulation.
Despite its clinical efficacy and safety, TPNS faces three primary hurdles to widespread adoption.
The first hurdle is reimbursement and coverage. Currently, Zoll relies on temporary and regional coverage rather than a National Coverage Decision. The TPNS implant procedure uses a temporary CPT code 0424T (Medicare payment level of ~$30K), while the IPG and stimulation leads are billed under HCPCS code C1823 specific to transvenous neuromodulation (Medicare payment level of ~$29K).
A significant improvement took effect this year when a landmark CMS rule overhauled the “prior authorization“ process. Insurers must now provide specific clinical reasons for denials and complete reviews within seven calendar days (often 3–5 days), down from the previous 14-day window. Insurers can no longer issue a vague “not covered” decision; they must cite a specific reason and the exact clinical criteria used, which strengthens physicians’ ability to file appeals.
The second hurdle is the limited number of specialized centers capable of performing TPNS lead insertion. One potential solution is expanding training to interventional and general cardiologists, who already gain familiarity with temporary transvenous pacing during their fellowships.
The third hurdle is the perceived low priority Zoll Medical places on TPNS therapy. Sleep apnea is just one of eight business segments at Zoll, and with annual revenue of $250–$300 million for this segment (including the WatchPAT device for detecting sleep apnea), it represents is a small share of Zoll’s $2.6 billion total annual revenue.
If these barriers are addressed, TPNS for CSA could become a billion-dollar market. This would place it on a similar trajectory to hypoglossal nerve stimulation for OSA, where the market leader, Inspire Medical, is expected to reach $1.0 billion in revenue by the end of 2026.
