Upper airway stimulation device failure: A 7-year single center experience.

OBJECTIVE: To identify and report a single center experience with upper airway stimulator device-related failures. STUDY DESIGN: Retrospective case series. SETTING: Single tertiary academic center. METHODS: Retrospective data on 352 patients who underwent UAS surgery with an Inspire device from 2016 to 2023 was collected, including demographics, comorbidities, and nature of device failure requiring revision surgery. RESULTS: Out of the 348 patients included in our analysis, 16 (4.6 %) required revision due to device failure, with an average interval of 772 days (∼2 years) between initial implant and revision. Most failures were attributed to respiratory sensing lead damage (n = 11, 68.8 %), resulting in high system impedance and subsequent device malfunction. Lead fracture causes varied, including idiopathic occurrences and potential trauma. Lead migration was noted in one case (6.3 %), where the hypoglossal electrode detached from the nerve. Two patients (12.3 %) required implantable pulse generator (IPG) replacement, one after experiencing trauma and the other due to unclear source of malfunction. One patient (6.3 %) required complete system replacement following high lead impedance and absent tongue motion. The last patient required replacement of both the IPG and respiratory lead after experiencing high lead impedance (6.3 %). CONCLUSION: Respiratory sensing lead fracture emerged as the leading cause of device failure in this cohort, underscoring the need to address this under-reported issue, potentially linked to the time lapse after device implantation.

Complications and device failures associated with urolift: Findings from the MAUDE database.

INTRODUCTION: Urolift is an established intervention for symptoms of bladder outflow obstruction caused by benign prostate enlargement. Reported advantages include its minimally invasive profile, short learning curve and feasibility as a day case procedure. Our aim was to use a national registry as a means to evaluate the nature of complications and device failures that have been documented to occur. METHODS: Retrospective review was performed of the US Manufacturer and User Facility Device Experience (MAUDE) database, a prospective register, which contains voluntarily submitted adverse events associated with surgical devices. Information collected include event timing, underlying cause, procedural completion, complications and mortality status. RESULTS: Between 2016 and 2023, 103 device failures, 5 intra-operative complications and 165 post-operative complications (early: 151, late: 14) were registered. The commonest device problem (56%, n = 58) was failure of the implant to deploy with subsequent requirement for complete replacement. There were 50 cases of documented urosepsis. 62 patients with post operative haematuria were registered including 12 that underwent emergency embolisation. Other complications included stroke (n = 5), pulmonary embolism (n = 3) and necrotising fasciitis (n = 1). Twelve ITU admissions were registered. In the reports, 22 cases were filed that recorded a hospital stay of 7 days or more. Eleven deaths were captured in the database over the study period. CONCLUSION: While urolift is recognised as less invasive intervention compared to alternatives such as transurethral resection of the prostate, serious adverse events have been reported to occur including death. Our findings can provide learning points for surgeons and allow for improved patient counselling and treatment planning accordingly.

Improving business performance through TPM method: The evidence from the production and processing of crude oil.

Nowadays, customers expect manufacturers to supply high quality products, on-time deliveries and competitive prices. The consequence of the increased market requirements is the need to maintain high reliability and efficiency of machines and the production process. The existing methods of production management have proved to be inefficient enough to maintain the company's competitive position on the market. The Total Productive Maintenance (TPM) concept is one of the tools to maximize equipment efficiency by establishing an optimal relationship between people and machines. The aim of the article is to present the issues related to TPM and demonstrate in the process of empirical research that it serves the purpose of improving efficiency and supports quality in the enterprise. The considerations are based on the thesis that TPM is an economical variant of maintenance and guarantees stability, quality and maximization of production efficiency. The article presents the results of empirical research in an enterprise extracting and processing pre-crudes and gas from Caspian Sea. The data from the SAP management system of the investigated enterprise were used. Based on 146 maintenance orders for 40 devices, a correlation between preventive and corrective maintenance was determined using statistical tools. The main goal of the study was to show whether preventive maintenance reduces the occurrence of failures contributing to the elimination of disturbances in the production process. In addition, we analyzed real cases of equipment failures to answer the question whether the procedure of preventive maintenance of equipment in the studied population would prevent the occurrence of these defects. The empirical study demonstrated a clear impact of Preventive Maintenance on limiting the occurrence of equipment failures, and thus production disturbances.

The Dewey Monitor: Pulse Oximetry can Warn of Hypoxia in an Immersed Rebreather Diver in Multiple Scenarios.

Divers who wish to prolong their time underwater while carrying less equipment often use devices called rebreathers, which recycle the gas expired after each breath instead of discarding it as bubbles. However, rebreathers' need to replace oxygen used by breathing creates a failure mechanism that can and frequently does lead to hypoxia, loss of consciousness, and death. The purpose of this study was to determine whether a pulse oximeter could provide a useful amount of warning time to a diver with a rebreather after failure of the oxygen addition mechanism. Twenty-eight volunteer human subjects breathed on a mixed-gas rebreather in which the oxygen addition system had been disabled. The subjects were immersed in water in four separate environmental scenarios, including cold and warm water, and monitored using pulse oximeters placed at multiple locations. Pulse oximeters placed on the forehead and clipped on the nasal ala provided a mean of 32 s (±10 s SD) of warning time to divers with falling oxygen levels, prior to risk of loss of consciousness. These devices, if configured for underwater use, could provide a practical and inexpensive alarm system to warn of impending loss of consciousness in a manner that is redundant to the rebreather.

Adverse Events in Hypoglossal Nerve Stimulator Implantation: 5-Year Analysis of the FDA MAUDE Database.

OBJECTIVE: Use of hypoglossal nerve stimulator implantation has dramatically improved the surgical treatment of multilevel airway collapse during obstructive sleep apnea (OSA). Understanding causes of adverse events and their impact on patients undergoing stimulator implantation will help improve patient preparation and surgical practices to avoid future complications. STUDY DESIGN: This study is a retrospective review of the US Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database, a publicly available voluntary reporting system. SETTING: National patient event database. METHODS: The MAUDE database was searched for reports associated with the terms "hypoglossal nerve stimulator" and "Inspire," being the only currently FDA-approved system for upper airway stimulation for OSA. All records were searched with the events limited in dates between May 2014 and September 2019. RESULTS: A total of 132 patient reports were identified over the 5-year inclusion period, containing 134 adverse events. The reported adverse events resulted in 32 device revision procedures as well as 17 explantations. Device migration and infection were 2 of the most commonly reported adverse events. Complications not witnessed in previous large-scale clinical trials included pneumothorax, pleural effusion, and lead migration into the pleural space. CONCLUSION: Previous data have demonstrated hypoglossal nerve stimulator implantation results in reliable OSA improvement. However, a number of technical difficulties and complications still exist during the perioperative period, which should be communicated to patients during the surgical consent process.

Adverse events associated with the Inspire implantable hypoglossal nerve stimulator: A MAUDE database review.

BACKGROUND: Implantable hypoglossal nerve stimulation (HNS) has been found to be a safe and effective therapy for patients with obstructive sleep apnea, and patient adherence to treatment has been found to be as high as 86% after 12 months of therapy. OBJECTIVE: The purpose of this study is to review the medical device reports (MDRs) submitted to the Food and Drug Administration's (FDA) Manufacturer and User Device Facility Experience (MAUDE) database to identify adverse events related to HNS therapy that could hinder compliance. METHODS: A search of the FDA MAUDE database was conducted using the product code "MNQ" for "Inspire stimulator for sleep apnea." Reports of adverse events associated with Inspire for sleep apnea from January 2000 to May 2020 were included for analysis. From these included reports, event variables were collected, including event setting, adverse event to patient, iatrogenic injury, device malfunction, interventions, and root causes. Results were compiled and reviewed. RESULTS: The search query yielded 180 reports that met inclusion criteria, containing a total of 196 adverse events. The most commonly reported adverse events to patients were infection (n = 50, 34.2%), neuropraxia (n = 22, 15.1%) and hematoma/seroma (n = 17, 11.6%). A total of 83 adverse events (42.3%) required reoperation. The most common reoperations performed for adverse events to patients were explantation (n = 30, 46.2%) and device repositioning/lead revision (n = 24, 36.9%), while the most common reoperation performed for device malfunctions was device replacement (n = 10, 55.6%). CONCLUSION: In attempting to further improve patient compliance, understanding these device malfunctions and adverse events related to HNS implantation or usage is crucial for the identification of potential causes of patient non-adherence.

Sacral Neuromodulation Lead Twisting Causes Migration and Loss of Efficacy.

OBJECTIVE: This study aimed to present 2 cases with unusual lead complications in InterStim devices implanted in patients with refractory overactive bladder symptoms. MATERIALS: Two patients with InterStim implants presented with loss of efficacy. Both patients required lead revision surgery with findings of a twisted lead with associated lead migration. RESULTS: In both cases, revision surgery revealed twisting of the InterStim lead causing retrograde lead displacement. Patients were managed with lead removal and placement of a new lead. At the time of revision, one patient had a seroma within a large pocket of the implantable pulse generator (IPG) site, which was managed with closure and development of a new IPG pocket. In both cases, revision with new lead placement resulted in significant symptom improvement. CONCLUSIONS: Sacral neuromodulation lead complications are known to be among the most consequential adverse events. We report the first 2 cases, to our knowledge, of patients presenting with an InterStim device that lost efficacy due to lead twisting and subsequent retrograde lead migration, likely due to rotation of the IPG within the gluteal pocket. This finding is easily remedied with IPG pocket revision and lead replacement.

DBS dysfunction mimicking transient ischemic attacks-a case report.

We report on a patient with thalamic deep brain stimulation (DBS) for essential tremor who was admitted to a stroke unit with transient vertigo, dysarthria, and gait disturbance. Transient ischemic attacks were assumed but fluctuating neurological symptoms persisted until presentation to a DBS center. Here, unstable high monopolar impedances of the right-hemispheric electrode contacts were detected. Surgical revision revealed a fracture of the pocket adaptor connecting this electrode to the impulse generator. Replacement resulted in stable impedances and remitted the transient neurological symptoms. Emergency and stroke doctors should be aware of neurological symptoms induced by technical dysfunctions in DBS.

17-Year Single Center Retrospective Review of Rate, Risk Factors and Outcomes of Lead Breakage during Sacral Neuromodulation Lead Removal.

PURPOSE: One risk of removal of a tined sacral neuromodulation lead is breakage, resulting in a retained lead fragment. We report lead breakage rates, risk factors and outcomes of retained fragments. MATERIALS AND METHODS: We report on 464 tined lead removals from 2002 to 2018. Clinical and surgical factors were reviewed and appropriate statistical analysis performed. Retained fragments were reviewed for fragment description and long-term complications. RESULTS: A total of 464 tined lead removals were included, with 35 lead breaks identified, for a rate of 7.5% (35). Factors associated with breakage included male gender (OR 6.58, 95% CI 2.54-17.01, p=0.001) and diabetes (OR 2.42, 95% CI 1.05-5.58, p=0.019). A shorter time since implantation was protective (OR 0.86, 95% CI 0.76-0.98, p=0.002). There was no difference in breakage rate based on age, weight, history of prior revision, bilateral leads, reason for lead removal, surgical technique or surgeon. Of the 35 breaks 27 had imaging available. Of these 66% (18) broke in the tined region and 81% (22) were ghost leads. Most patients (80%, 28 of 35) with retained lead fragments received another implant. Only 1 patient had a related complication of additional surgery for pain related to the fragment. CONCLUSIONS: There is a low rate of tined lead breakage during lead removal. However, it is higher than the manufacturer estimate. Protective factors include a shorter time between implant and lead revision. The most common location for lead breakage is in the region of the tines, most are ghost fragments and long-term complications are uncommon.

Making Locally Fabricated Phototherapy Devices Work Better.

BACKGROUND: The efficiency of a phototherapy (PT) device is a function of the irradiance delivered by the device at the surface of the skin. Because cost limits the ability of health care facilities in low- and middle-income countries to procure commercial PT devices, efforts have gone into local fabrication of devices for use in health care facilities in Nigeria. Evaluation of such fabricated devices is yet to be conducted. OBJECTIVE: To identify and document essential features of locally fabricated phototherapy (FPT) devices in use in Nigeria. MATERIALS AND METHODS: A cross sectional survey of locally FPT devices available in health facilities providing newborn health care services was conducted as part of evaluating neonatal jaundice management services in Kaduna State. Each FPT was characterized with respect to mobility/portability, adjustability, lamp type, number and color of lamps used. The irradiance of each device was measured using Model 22 Olympic BiliMeter™ at the facility's traditional PT distance and also at a distance at which optimum irradiance is delivered by the device. RESULTS: A total of 54 PT devices were in use. Thirty-two (59.3%) of these devices were locally fabricated while others were obtained from commercial sources. Of the fabricated devices 22/32 (68.8%) were non-adjustable while the remaining 10 devices were adjustable but with limited adjustability. Only 5/32 (15.6%) of the FPT devices used special blue fluorescent lamps. The majority, 68.8% (22/32) of the FPT devices used ordinary low-intensity blue lamps while the remaining 5/32 (15.6%) devices used white light fluorescent lamps. None of the devices used light emitting diodes as a PT light source. Only three fabricated devices offered irradiance (9.4, 13.6 and 33 µW/cm2/nm) at the facilities' traditional distances for PT. CONCLUSIONS: FPT devices in use in Kaduna, functioned sub-optimally because of technically inadequate designs. The devices will need to be designed to especially enable adjustability to vary distance between device and patient's skin and the use of lamps which offer high irradiance.

Migration and surgical retrieval of a broken dental needle: a literature review and case report.

Although the incidence of broken needles in dental practice is minimal, needle breakage can occur as a result of manufacturing defects, inadequate patient management, or poor practitioner technique. Retrieval of a broken needle is justified not only because of the potential for needle migration but also because of psychological and medicolegal considerations. This case report describes the surgical removal of a dental needle that fractured during an attempt at local anesthesia. Identifying the precise location of the broken needle fragment and its relationship with the surrounding bones, vessels, and nerves is essential to designing an adequate treatment plan. If surgical retrieval is indicated, it should be performed immediately, especially in cases in which the needle fragment has not been bent or deformed. In the present case, the use of C-arm fluoroscopy aided the surgical removal while saving time and reducing the cost of treatment.

Removal of a broken acupuncture needle in retroperitoneum by laparoscopy: a case report.

BACKGROUND: Acupuncture is a famous traditional medicine in China, but the complications caused by broken acupuncture needles have been rarely reported. It seems easy to remove the foreign matters usually, but things become difficulty in special issues. Here, we reported a recently encountered case to provide an important teaching point of treating a chronically retained broken needle in retroperitoneum. CASE PRESENTATION: A 42-year-old man presented with a chronically retained broken needle in his body after acupuncture therapy two years ago. However, due to the discomfort at the left back recently and ordinary inconvenience such as security check, he came to our hospital for minimally invasive surgery. He was introduced to our department because the broken needle had migrated from subcutaneous to adipose tissue in retroperitoneum during the two years. Considering the position of the broken needle, the patient was performed by laparoscopy in general anesthesia. The operation time was about 31 min and there were only three 7 mm incisions in the left lateral abdominal wall. The X-ray exam was performed to confirm that the broken needle was removed integrally. The patients begun normal activity at 6 h after surgery and was discharged on the second day after surgery. CONCLUSIONS: Acupuncture is widely used for pain treatment in China, but how to handle the complication of acupuncture needle broken in body are rarely reported. Laparoscopy will be the reasonable choice for treating needles broken in retroperitoneum.

Quantification of Electromechanical Coupling to Prevent Inappropriate Implantable Cardioverter-Defibrillator Shocks.

OBJECTIVES: This study sought to test specialized processing of laser Doppler signals for discriminating ventricular fibrillation (VF) from common causes of inappropriate therapies. BACKGROUND: Inappropriate implantable cardioverter-defibrillator (ICD) therapies remain a clinically important problem associated with morbidity and mortality. Tissue perfusion biomarkers, implemented to assist automated diagnosis of VF, sometimes mistake artifacts and random noise for perfusion, which could lead to shocks being inappropriately withheld. METHODS: The study tested a novel processing algorithm that combines electrogram data and laser Doppler perfusion monitoring as a method for assessing circulatory status. Fifty patients undergoing VF induction during ICD implantation were recruited. Noninvasive laser Doppler and continuous electrograms were recorded during both sinus rhythm and VF. Two additional scenarios that might have led to inappropriate shocks were simulated for each patient: ventricular lead fracture and T-wave oversensing. The laser Doppler was analyzed using 3 methods for reducing noise: 1) running mean; 2) oscillatory height; and 3) a novel quantification of electromechanical coupling which gates laser Doppler relative to electrograms. In addition, the algorithm was tested during exercise-induced sinus tachycardia. RESULTS: Only the electromechanical coupling algorithm found a clear perfusion cut off between sinus rhythm and VF (sensitivity and specificity of 100%). Sensitivity and specificity remained at 100% during simulated lead fracture and electrogram oversensing. (Area under the curve running mean: 0.91; oscillatory height: 0.86; electromechanical coupling: 1.00). Sinus tachycardia did not cause false positive results. CONCLUSIONS: Quantifying the coupling between electrical and perfusion signals increases reliability of discrimination between VF and artifacts that ICDs may interpret as VF. Incorporating such methods into future ICDs may safely permit reductions of inappropriate shocks.

Detection of high-frequency artifact as a function of pulse generator algorithms and outer-insulation material.

BACKGROUND: A high rate of malfunction, predominantly intermittent high-frequency artifacts (HFAs), has been recently reported in Abbott Medical Tendril pacing leads. OBJECTIVE: To investigate the factors associated with the occurrence of HFAs on Tendril leads using a commonly used comparator lead for a control. METHODS: We reviewed institutional data for Medtronic CapSureFix 5076 and Abbott Medical Tendril pace-sense leads retrospectively. Recordings deemed to be due to electromagnetic interference and far-field oversensing were not included in the classification of HFAs. RESULTS: A total of 7673 leads were analyzed: 1628 Optim-insulated Tendril leads, 825 non-Optim Tendril leads, and 5220 CapSureFix 5076. HFAs were seen in 212 leads and were more frequently observed in Tendril compared to CapSureFix leads during a mean follow-up of 4.1 ± 3.6 years. Lower age at implant, defibrillator systems, atrial position, and connection to an Abbott Medical generator were associated with increased HFA. In multivariable analysis, only connection to Abbott Medical generators (odds ratio 7.686, P < .001) and age (odds ratio 0.988 per year, P = .016) were independently associated with HFAs on pace-sense leads. In an Abbott-generator-only analysis, Optim-insulated Tendril leads were more likely to display HFAs than non-Optim Tendril leads but not Medtronic CapSureFix 5076 leads. CONCLUSION: Abbott Medical pulse generators independently predict HFA in Tendril and CapSureFix 5076 leads, likely the result of displaying short or low-amplitude noise episodes that other devices do not record. When restricted to Abbott generators only, Optim-insulated Tendril leads show an increased incidence of HFAs when compared to non-Optim Tendril leads but not CapSureFix 5076 leads.

Recommendation of New Medical Alarms Based on Audibility, Identifiability, and Detectability in a Randomized, Simulation-Based Study.

OBJECTIVES: Accurate and timely identification of existing audible medical alarms is not adequate in clinical settings. New alarms that are easily heard, quickly identifiable, and discernable from one another are indicated. The "auditory icons" (brief sounds that serve as metaphors for the events they represent) have been proposed as a replacement to the current international standard. The objective was to identify the best performing icons based on audibility and performance in a simulated clinical environment. DESIGN: Three sets of icon alarms were designed using empirical methods. Subjects participated in a series of clinical simulation experiments that examined the audibility, identification accuracy, and response time of each of these icon alarms. A statistical model that combined the outcomes was used to rank the alarms in overall efficacy. We constructed the "best" and "worst" performing sets based on this ranking and prospectively validated these sets in a subsequent experiment with a new subject sample. SETTING: Experiments were conducted in simulated ICU settings at the University of Miami. SUBJECTS: Medical trainees were recruited from a convenience sample of nursing students and anesthesia residents at the institution. INTERVENTIONS: In Experiment 1 (formative testing), subjects were exposed to one of the three sets of alarms; identical setting and instruments were used throughout. In Experiment 2 (summative testing), subjects were exposed to one of the two sets of alarms, assembled from the best and worst performing alarms from Experiment 1. MEASUREMENTS AND MAIN RESULTS: For each alarm, we determined the minimum sound level to reach audibility threshold in the presence of background clinical noise, identification accuracy (percentage), and response time (seconds). We enrolled 123 medical trainees and professionals for participation (78 with < 6 yr of training). We identified the best performing icon alarms for each category, which matched or exceeded the other candidate alarms in identification accuracy and response time. CONCLUSIONS: We propose a set of eight auditory icon alarms that were selected through formative testing and validated through summative testing for adoption by relevant regulatory bodies and medical device manufacturers.

Device Malfunctions and Complications Associated with Benign Prostatic Hyperplasia Surgery: Review of the Manufacturer and User Facility Device Experience Database.

Introduction and Objectives: Multiple surgical therapies for benign prostatic hyperplasia (BPH) have been developed to decrease complications and increase provider efficiency. We investigated contemporary BPH treatment device-related adverse events by searching a publicly available database. Materials and Methods: The Manufacturer and User Facility Device Experience (MAUDE) database was queried for contemporary BPH treatments. All devices were evaluated for malfunction, patient complications, and manufacturer review. The MAUDE adverse event classification system was used to standardize complications. Univariate analysis was performed to identify associations between BPH devices and adverse events. Results: A total of 2567 reports were identified: transurethral resection of the prostate (TURP) 197 (7.67%), holmium laser enucleation of the prostate (HoLEP) 39 (1.52%), GreenLight™ 2315 (90.2%), and UroLift® 16 (0.62%). The most common deviations for each modality included cutting loop detachment during TURP 116 (58.9%), morcellator dysfunction for HoLEP 23 (58.9%), tip fracture/detachment for GreenLight (68.8%), and failure to deploy during UroLift 10 (62.5%). Only 18 (0.7%) patients required medical/surgical management (MAUDE II-IV) due to a device complication. No significant relationship was seen between each modality and complications; however, morcellator use (27.8%) was observed in higher grade complications. Manufacturer review occurred in 61.7% of cases, with 41.3% of reviewed cases finding the operator the cause of the malfunction. Conclusion: Each BPH modality investigated had minimal patient harm with over 99% of patients experiencing no complication after device malfunction. Of note, great care should be taken with morcellator use during HoLEP as it had the greatest number of MAUDE II to IV complications among all devices. Manufacturer review revealed that over 40% of cases were due to misuse by the user. Therefore, urologists should select the modalities they are most familiar with to decrease patient harm and prevent device malfunctions.

Efficacy of the current of injury in envisaging the dislodgement of leads implanted in the right atrial septum or the right ventricular septum.

BACKGROUND: The implantation of leads in the right atrial septum (RAS) or the right ventricular septum (RVS) is technically challenging, and dislodgement occurs occasionally. This study aims to determine a predictor for the dislodgement of leads implanted in the RAS or RVS. METHODS: This retrospective cohort study enrolled 137 consecutive patients who underwent the cardiac implantable electronic devices implantation, using active fixation leads in the RAS and RVS. We compared the pacing threshold, R- or P-wave amplitude, slew rate, and presence of the current of injury (COI) between dislodged and nondislodged leads. RESULTS: We performed lead fixation for 74 and 125 times in the RAS and RVS, respectively. Atrial lead dislodgement occurred five times (6.8%) intraoperatively and five times (6.8%) postoperatively, whereas ventricular lead dislodgement occurred eight times (6.4%) intraoperatively and three times (2.4%) postoperatively. Although there were no lead parameters that showed a significant difference common to RAS lead and RVS lead, the presence of the COI was significantly different between nondislodged and dislodged leads in both the RAS and RVS (atrial leads: 57.8% vs 0%, P < 0.001; ventricular leads: 67.5% vs 9.1%, P < 0.001). The positive predictive value of COI presence for predicting no lead dislodgement was 100% and 98.7% in the RAS and RVS, respectively. CONCLUSION: Lead dislodgement is more likely when the COI is absent; documentation of COI should be pursued during lead implantation in challenging sites as the RAS and RVS.

Failure to detect life-threatening arrhythmias in ICDs using single-chamber detection criteria.

BACKGROUND: There are anecdotal reports of sudden death despite a functional implantable cardioverter defibrillator (ICD). We sought to describe scenarios leading to fatal or near-fatal outcome due to inappropriately inhibited ICD therapy in devices programmed with single-chamber detection criteria. METHODS: Programmed settings, episode lists, and intracardiac electrograms from 24 patients with a life-threatening event (n = 12) or fatal outcome (n = 12) related to failed ventricular arrhythmia detection were used to clarify the underlying scenario. RESULTS: Fifty episodes of failed ventricular arrhythmia detection were identified and categorized into six scenarios: (1) spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) with a rate below the detection limits, (2) misclassification of polymorphic VT (PVT) or VF as supraventricular tachycardia (SVT), (3) misclassification of VT/VF as cluster of nonsustained VT episodes, (4) misclassification of monomorphic VT (MVT) as SVT, (5) inappropriate shock abortion, and (6) false termination detection. These scenarios occurred respectively 6, 9, 3, 9, 8, and 15 times. In 9/9 (100%) patients with PVT/VF classified as SVT, rate stability was active for rates ranging from 222 to 250 beats/min. MVT detected as SVT was due to the sudden onset criterion in 7/9 (78%) patients and twice a consequence of the rate stability criterion active for rates ranging from 200 to 250 beats/min. CONCLUSION: We describe six scenarios leading to failure of ventricular arrhythmia detection in a single-chamber detection setting withholding life-saving therapy. These scenarios are more likely to occur with high-rate programming and long detection times, especially if combined with rate stability and sudden onset.