Magnetic resonance imaging interactions with a sacral neuromodulation system

Aims

Sacral neuromodulation (SNM) has successfully treated patients with functional urinary and/or bowel disorders for more than two decades. Historically, patients with the InterStim system (Medtronic) were contraindicated for Magnetic Resonance Imaging (MRI) scans. In 2012, Medtronic obtained Food and Drug Administration (FDA) approval for allowing 1.5 Tesla (T) MRI head scans. In September 2019, the Axonics System (Axonics) received FDA approval for 1.5 T full‐body MR Conditional labeling and then 3 T full‐body MR Conditional labeling in July 2020. In August 2020, Medtronic received 1.5 and 3 T full‐body MR Conditional labeling from the FDA for their new SNM systems (InterStim II and Micro devices with SureScan^TM leads). With the advancements in MRI technology and availability of full‐body MRI eligible SNM systems, it is important for physicians to better understand MRI safety for these systems.

Methods

This paper explains the fundamentals of MRI physics, its interactions with active implantable medical devices (AIMDs), the subsequent potential safety hazards with emphasis on radio frequency (RF)‐related safety, and the risks associated with “Off‐label” scans, including abandoned and broken leads.

Results

MRI guidelines provided by the AIMD device manufacturer should be followed to ensure MRI scan safety and avoid any unnecessary risk to patients.

Conclusions

MRI guidelines provided by the device manufacturer are the best resource for guidance for performing safe MRI scanning. Specific conditions should be fully understood and generalizations on MRI safety claims based on partial analysis or case studies should be avoided.

Two-year outcomes of the ARTISAN-SNM study for the treatment of urinary urgency incontinence using the Axonics rechargeable sacral neuromodulation system

AIMS

Sacral neuromodulation (SNM) is a guideline-recommended treatment with proven therapeutic benefit for urinary urgency incontinence (UUI) patients. The Axonics® System is the first Food and Drug Administration-approved rechargeable SNM system and is designed to deliver therapy for a minimum of 15 years. The ARTISAN-SNM study was designed to evaluate UUI participants treated with the Axonics System. Two-year follow-up results are presented.

METHODS

One hundred and twenty-nine UUI participants underwent implantation with the Axonics System. Therapeutic response rate, participant quality of life (QoL), and satisfaction were determined using 3-day voiding diaries, ICIQ-OABqol, and satisfaction questionnaires. Participants were considered responders if they had a 50% or greater reduction in UUI episodes post-treatment. As-treated and Completers analyses are presented.

RESULTS

At 2 years, 93% of the participants (n = 121 Completers at 2 years) were therapy responders, of which 82% achieved ≥ 75% reduction in UUI episodes and 37% were dry (100% reduction). Daily UUI episodes reduced from 5.6 ± 0.3 at baseline to 1.0 ± 0.2 at 2 years. Statistically significant improvements in ICIQ-OABqol were reported. All participants were able to recharge their device and 94% of participants reported that the recharging frequency and duration were acceptable. Participant demographics nor condition severity were correlated with clinical outcomes or recharging experience. No unanticipated or serious device-related adverse events occurred.

CONCLUSIONS

At 2 years, participants treated with the Axonics System demonstrated sustained safety and efficacy, high levels of satisfaction with therapy and recharging. Participant-related factors were not associated with efficacy or recharging outcomes, indicating the reported results are applicable to a diverse population.

One-year outcomes of the ARTISAN-SNM study with the Axonics System for the treatment of urinary urgency incontinence

Aims

Sacral neuromodulation (SNM) is a guideline‐recommended treatment for voiding dysfunction including urgency, urge incontinence, and nonobstructive retention as well as fecal incontinence. The Axonics® System is a miniaturized, rechargeable SNM system designed to provide therapy for at least 15 years, which is expected to significantly reduce revision surgeries as it will not require replacement as frequently as the non‐rechargeable SNM system. The ARTISAN‐SNM study is a pivotal study designed to treat patients with urinary urgency incontinence (UUI). Clinical results at 1‐year are presented.

Methods

A total of 129 eligible UUI patients were treated. All participants were implanted with a quadripolar tined lead and neurostimulator in a single procedure. Efficacy data were collected using a 3‐day bladder diary, a validated quality of life questionnaire (ICIQ‐OABqol), and a participant satisfaction questionnaire. Therapy responders were defined as participants with ≥50% reduction in UUI episodes compared to baseline. Data were analyzed on all 129 participants.

Results

At 1 year, 89% of the participants were therapy responders. The average UUI episodes per day reduced from 5.6 ± 0.3 at baseline to 1.4 ± 0.2. Participants experienced an overall clinically meaningful improvement of 34 points on the ICIQ‐OABqol questionnaire. All study participants (100%) were able to recharge their device at 1 year, and 96% of participants reported that the frequency and duration of recharging was acceptable. There were no serious device‐related adverse events.

Conclusions

The Axonics System is safe and effective at 1 year, with 89% of participants experiencing clinically and statistically significant improvements in UUI symptoms.

Implantation of a defibrillator in a patient with an upper airway stimulation device

The patient is a 62-year-old man with continuous positive airway pressure-intolerant obstructive sleep apnea who was enrolled in a study for a hypoglossal nerve upper airway stimulation device (UAS). Nearly 2.5 years later, he was admitted to the hospital for unstable angina. Diagnostic workup revealed a prior myocardial infarction, an ejection fraction of 30% on maximal medical therapy, and episodes of nonsustained ventricular tachycardia. During hospitalization, the patient received an implantable cardioverter defibrillator (ICD). This is the first reported case of simultaneous use of a UAS and an ICD, and we report no untoward device interference between the two implantable devices.

Treating obstructive sleep apnea with hypoglossal nerve stimulation

BACKGROUND

Reduced upper airway muscle activity during sleep is fundamental to obstructive sleep apnea (OSA) pathogenesis. Hypoglossal nerve stimulation (HGNS) counteracts this problem, with potential to reduce OSA severity.

STUDY OBJECTIVES

To examine safety and efficacy of a novel HGNS system (HGNS, Apnex Medical, Inc.) in treating OSA.

PARTICIPANTS

Twenty-one patients, 67% male, age (mean ± SD) 53.6 ± 9.2 years, with moderate to severe OSA and unable to tolerate continuous positive airway pressure (CPAP).

DESIGN

Each participant underwent surgical implantation of the HGNS system in a prospective single-arm interventional trial. OSA severity was defined by apnea-hypopnea index (AHI) during in-laboratory polysomnography (PSG) at baseline and 3 and 6 months post-implant. Therapy compliance was assessed by nightly hours of use. Symptoms were assessed using the Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire (FOSQ), Calgary Sleep Apnea Quality of Life Index (SAQLI), and the Beck Depression Inventory (BDI).

RESULTS

HGNS was used on 89% ± 15% of nights (n = 21). On these nights, it was used for 5.8 ± 1.6 h per night. Nineteen of 21 participants had baseline and 6-month PSGs. There was a significant improvement (all P < 0.05) from baseline to 6 months in: AHI (43.1 ± 17.5 to 19.5 ± 16.7), ESS (12.1 ± 4.7 to 8.1 ± 4.4), FOSQ (14.4 ± 2.0 to 16.7 ± 2.2), SAQLI (3.2 ± 1.0 to 4.9 ± 1.3), and BDI (15.8 ± 9.0 to 9.7 ± 7.6). Two serious device-related adverse events occurred: an infection requiring device removal and a stimulation lead cuff dislodgement requiring replacement.

CONCLUSIONS

HGNS demonstrated favorable safety, efficacy, and compliance. Participants experienced a significant decrease in OSA severity and OSA-associated symptoms.

CLINICAL TRIAL INFORMATION

NAME: Australian Clinical Study of the Apnex Medical HGNS System to Treat Obstructive Sleep Apnea.

REGISTRATION NUMBER

NCT01186926. URL: http://clinicaltrials.gov/ct2/show/NCT01186926.