Phrenic nerve stimulation for central sleep apnea: a single institution experience.

PURPOSE: Phrenic nerve stimulation (PNS) was approved by the Food and Drug Administration (FDA) to treat moderate to severe central sleep apnea. We report here, results of a retrospective study regarding our institutional outcomes at one year. In this study we evaluated the change in the apnea hypopnea index, epworth sleepiness score, and functional outcomes of sleep score at one year post implant. METHODS: This is a retrospective analysis of patients ≥ 18 years of age who had PNS implanted for moderate to severe CSA at the Ohio State University Wexner Medical Center apnea between Feb 1, 2018 to July 1, 2021. Sleep disordered breathing parameters and objective sleepiness as measured by the Epworth Sleepiness Scale (ESS) scores, and Functional Outcomes of Sleep Questionnaire (FOSQ) scores were assessed at baseline and one-year post-implant. RESULTS: Twenty-two patients were implanted with PNS at OSU between February 1, 2018 and May, 31, 2022. The AHI showed a statistically significant decrease from a median of 40 events/hour at baseline to 18 at follow-up (p-value = 0.003). The CAI decreased from 16 events/hour to 2 events/hour (p-value of 0.001). The obstructive apnea index, mixed apnea index, and hypopnea index did not significantly change. The ESS scores had a statistically significant improvement from a median score of 12 to 9 (p-value = 0.028). While the FOSQ showed a trend to improvement from 15.0 to 17.8, it was not statistically significant (p-value of 0.086). CONCLUSION: Our study found that PNS therapy for moderate to severe CSA improves overall AHI and CAI. Objective sleepiness as measured by the ESS also improved at one-year post implant.

Transvenous phrenic nerve stimulation: setting up a clinical program.

BACKGROUND: Central sleep apnea (CSA) is a form of sleep-disordered breathing caused by a lack of the drive to breathe during sleep. Phrenic nerve stimulation (PNS) was approved in 2017 for treatment of moderate to severe CSA. However, information on setting up a successful PNS program is lacking. We describe our institution's program to provide a framework to bridge the gap between clinical research and clinical application for PNS therapy. METHODS: The PNS program was created as a joint program between cardiology and sleep medicine. The program team included cardiologists, sleep medicine specialists, advanced practice providers, clinic managers, and staff who worked together in the evaluation, implantation, and management of patients. RESULTS: Thus far, 33 patients have been implanted at our institution. We have noted resolution of central apneas with PNS and improvement in patient sleep symptoms. The multidisciplinary clinic with cardiology and sleep medicine has led to high patient satisfaction and has facilitated a cohesive relationship between implant and management teams. CONCLUSIONS: PNS therapy is an effective treatment option for CSA. While the therapy treats central apneas, it will not affect upper airway obstruction. Proper patient identification is important and cooperative management between cardiology and sleep medicine enhances patient care and experience. Challenges of establishing a multidisciplinary program include identification of providers, clinic space, and scheduling. Once established, the program provides an important service to a vulnerable patient population.

Subcutaneous cardiac rhythm monitors: state of the art review.

Introduction: Subcutaneous cardiac rhythm monitors (SCRMs) provide continuous ambulatory electrocardiographic monitoring for surveillance of known and identification of infrequent arrhythmias. SCRMs have proven to be helpful for the evaluation of unexplained symptoms and correlation with intermittent cardiac arrhythmias. Successful functioning of SCRM is dependent on accurate detection and successful transmission of the data to the device clinic. As the use of SCRM is steadily increasing, the amount of data that requires timely adjudication requires substantial resources. Newer algorithms for accurate detection and modified workflow systems have been proposed by physicians and the manufacturers to circumvent the issue of data deluge.Areas covered: This paper provides an overview of the various aspects of ambulatory rhythm monitoring with SCRMs including indications, implantation techniques, programming strategies, troubleshooting for issue of false positive and intermittent connectivity and strategies to circumvent data deluge.Expert opinion: SCRM is an invaluable technology for prolonged rhythm monitoring. The clinical benefits from SCRM hinge on accurate arrhythmia detection, reliable transmission of the data and timely adjudication for possible intervention. Further improvement in SCRM technology is needed to minimize false-positive detection, improve connectivity to the central web-based server, and devise strategies to minimize data deluge.

Resource Use and Economic Implications of Remote Monitoring With Subcutaneous Cardiac Rhythm Monitors.

OBJECTIVES: This study reports resource use and economic implications of rhythm monitoring with subcutaneous cardiac rhythm monitors (SCRMs). BACKGROUND: SCRMs generate a substantial amount of data that requires timely adjudication for appropriate clinical care. Resource use for SCRM monitoring is not known. METHODS: The study included consecutive transmissions during 4 weeks from 1,811 SCRMs. Resource use was quantified by assessment of time commitment of device clinic personnel and electrophysiologists for data adjudication. Incidence and characteristics of false positive (FP) episodes were assessed. Impact of custom programming for arrhythmia detection on incidence of FP episodes and resource use was analyzed. RESULTS: A total of 1,457 transmissions (alerts = 462; full downloads = 995) were received during study period. Average device clinic personnel time for adjudication of 1 transmission was 15 ± 6 min. This totaled to 364 h spent (2.3 full-time staff) over the 4-week period, which translated into a salary cost of $12,000 U.S. dollars (USD). Average time spent by an electrophysiologist for 1 transmission was 1.5 ± 1 min and totaled to 37 h for 4 weeks, which translated into an estimated cost of $9,600 USD. Of 1,457 total transmissions, 512 (35%) represented multiple transmissions from the same patients, which resulted in no additional reimbursement. Incidence of FP episodes in the entire cohort was 50% and was variable in alert (60%) and full download (49%) (p = 0.04) transmissions. When SCRMs with manufacturer suggested nominal programming and institutional custom programming were compared, there was a reduction in FP episodes (55% vs. 16%; p = 0.01), which translated to a 34% reduction in resource use for data adjudication. CONCLUSIONS: SCRM data adjudication requires significant resources. Custom programming for SCRMs may overcome the data deluge.

Incidence of false-positive transmissions during remote rhythm monitoring with implantable loop recorders.

BACKGROUND: Implantable loop recorder (ILR) is preferred strategy for prolonged rhythm monitoring. OBJECTIVE: The purpose of this study was to report the incidence and causes of false-positive (FP) diagnoses during remote monitoring with ILR. METHODS: During a 4-week study period, all consecutive remote transmissions in patients with ILR (Reveal LINQ, Medtronic) implanted for atrial fibrillation (AF) surveillance, cryptogenic stroke (CS), and syncope were reviewed. A nurse specializing in device management and an electrophysiologist adjudicated all transmissions. Primary endpoint of the study was incidence of FP in patients with AF, CS, and syncope. RESULTS: A total of 695 remote transmissions (scheduled downloads: 414; Alerts: 281) sent from 559 patients were adjudicated. The majority of patients had ILR for AF surveillance (n = 321), followed by CS (n =168) and syncope (n = 70) with nominal programming for rhythm diagnosis. Incidence of FP transmissions during the study period was 46%, 86%, and 71% in patients with AF, CS, and syncope, respectively. Incidence of FP transmissions was higher in patients with CS and syncope than in patients with AF (P <.001). For scheduled transmissions, primary causes of FP were signal dropout and undersensing; for alert transmissions, primary reasons for FP were premature atrial and ventricular ectopy. CONCLUSION: Incidence of FP during remote monitoring with nominal settings on this ILR was substantial, ranging from 46% to 86% depending on the indication for implantation. Adjudication of these transmissions required a considerable time commitment from electrophysiologists and device clinic personnel but would be required to avoid misdiagnosis and potential errors in clinical management.