Additional left ventricular septal lead facilitates R-wave sensing of implantable cardioverter-defibrillator in arrhythmogenic right ventricular cardiomyopathy: a case report

Background

Implantable cardioverter-defibrillator (ICD) implantation is a key therapeutic option in arrhythmogenic right ventricular cardiomyopathy (ARVC) to prevent sudden cardiac death due to ventricular tachycardia (VT) and fibrillation (VF). However, sub-optimized R-wave sensing due to myocardium loss interferes with VT/VF identification and appropriate therapy. We tried to implant a 3830 lead to the left ventricular septum (LVS) to facilitate ICD sensing in an ARVC patient.

Case summary

A 68-year-old woman diagnosed with ARVC was scheduled to undergo ICD implantation. Initially, no sites with suitable R-wave amplitudes were found in the right ventricle (RV) to deploy the defibrillation lead (<3.0 mV). It was likely due to severe RV involvement, but the LVS myocardium was more preserved based on cardiac magnetic resonance imaging. Therefore, we implanted a 3830 lead into the deep area of the septum to facilitate R-wave sensing. During the procedure from the right to left septum, the R-wave amplitude significantly increased (2.6 to 4.3-7.1 mV). Left ventricular septum pacing was finally achieved with favourable R-wave sensing (9.9 mV 24 h post-operation). The 3830 lead was plugged into the IS-1 port, while the defibrillation lead was plugged into the DF-1 port. After a 4-month follow-up, the R-wave amplitude of the 3830 lead was 11.1 mV.

Discussion

When the R-wave sensing is not acceptable for ICD implantation in ARVC patients, it is critical to assess myocardial conditions comprehensively. If the septal myocardium is preserved, implanting a 3830 lead to the deep or LVS is feasible to improve R-wave sensing.

The BIOMONITOR III Injectable Cardiac Monitor: Clinical Experience with a Novel Injectable Cardiac Monitor

Background: Injectable cardiac monitors (ICMs) are leadless subcutaneous devices for long-term monitoring of arrhythmias. The BIOTRONIK BIOMONITOR III is a novel ICM with a miniaturized profile, long sensing vector, and simplified implantation technique. Methods: R-wave amplitude was recorded immediately after implantation, the day after implantation, and after 3 months. Follow-up was scheduled after 3 months or after an event. All data from the ICM were retrieved. The anatomical position of the ICM was determined post-implantation and after 3 months. A patient questionnaire was conducted after 3 months. Results: In 36 patients (mean age 67 ± 13 years; 40% male) an ICM was inserted. Six patients were not included in the final analysis. The median time from skin cut to wound closure was 6 [IQR 5–7] minutes. Mean R-wave amplitude increased over time (0.73 ± 32 mV vs. 0.78 ± 0.38 mV vs. 0.81 ± 0.39 mV; p = ns). Three months after implantation, the ICM was in an anatomically stable position. In 14 (47%) patients, true episodes were detected. False arrhythmia alerts were detected in 13 (43%) patients. The total number of false detections was low, and the patient satisfaction rate was high. Conclusion: Implantation of the novel BIOMONITOR III is fast and uncomplicated; its sensing characteristics are excellent and improve over time, and patient satisfaction is high.

The BioMonitor 2 insertable cardiac monitor: Clinical experience with a novel implantable cardiac monitor

INTRODUCTION

Implantable loop recorders (ILR) are leadless subcutaneous devices that allow cardiac monitoring for up to 3 years and are a valuable tool in the diagnosis of arrhythmias, cryptogenic stroke and unexplained syncope. The Biotronik BioMonitor 2 is a novel, insertable ILR allowing long-term continuous monitoring with wireless telemetry options.

METHODS

A single-center, prospective, observational study investigating the reliability of sensing quality and detection performance in the BioMonitor 2 ILR, as well as post-implantation patient satisfaction. R-wave amplitude was recorded immediately post implantation and 1 day post implantation, followed by extensive patient instruction. Follow-up was scheduled after 3 months, or after an event. Data from the ILR were retrieved, with documentation of all episodes, R-wave amplitude and noise burden. The anatomical position of the ILR was determined 1 day post implantation and after 3 months. A patient questionnaire was conducted after 3 months.

RESULTS

30 consecutive patients (mean age 71 ± 12 years, 56% male) were analyzed. Indications for ILR implantation were: unexplained syncope (n = 24, 80%), suspected atrial fibrillation (n = 4, 13%), cryptogenic stroke (n = 1, 3%) and palpitations (n = 1, 3%). Median time from skin cut to suture was 8 min. No complications occurred. Mean R-wave amplitude at implantation was 0.84 ± 0.32 mV, at day 1 post implantation 0.96 ± 0.31 mV, and after a mean follow-up of 85 ± 24 days 1.02 ± 0.47 mV (p = 0.01). The mean noise burden was 1.4 ± 2%.

CONCLUSION

Implantation of the novel BioMonitor 2 ILR is fast and uncomplicated. Initial sensing values are good and improve over time.

Sensing performance, safety, and patient acceptability of long-dipole cardiac monitor: An innovative axillary insertion

BACKGROUND

The recommended location for implantable cardiac monitor (ICM) insertion is the left pectoral region. We tested whether an innovative left axillary implantation approach could be applicable for a new ICM, characterized by a long sensing dipole.

METHODS

We considered a series of 55 patients consecutively implanted with a long-dipole ICM (BioMonitor 2); the first 30 subjects underwent prepectoral location insertion, while the subsequent 25 received the ICM in the axillary region. Sensing performances collected at 1-month follow-up were compared between the two groups. During the visit, each patient was also asked to fill in a brief questionnaire to assess patient acceptability of the device.

RESULTS

All patients had a successful insertion of ICM. Mean R-wave amplitude was 0.87 ± 0.44 mV in the prepectoral group and 1.00 ± 0.45 mV in the axillary one, without any significant difference. The percentage of patients with visible P wave was also comparable between the two approaches (65.5% vs 68.2%, P = 0.84). None of the patients reported device-related issues or discomfort, and ICM was generally well accepted and tolerated by all the involved patients.

CONCLUSION

Axillary insertion may represent a valid alternative to the standard one for long-dipole ICM technology providing not only patient acceptability but also high-quality sensing performances.

Performance of the New BioMonitor 2-AF Insertable Cardiac Monitoring System: Can Better be Worse?

BACKGROUND

Implantable loop recorders (ILR) are valuable tools for the investigation of patients with suspected arrhythmias. The BioMonitor 2-AF is a novel insertable ILR with enhanced atrial fibrillation (AF) detection algorithm and remote monitoring capability.

OBJECTIVE

The objective of this first-in-human study with the BioMonitor 2-AF was to analyze course of P-wave sensing performance and R-wave amplitude, prevalence of false and correctly sensed and classified episodes, and effectiveness of remote monitoring.

METHODS

All 19 patients who underwent ILR insertion were included in the BIOTRONIK Home Monitoring® system (BIOTRONIK GmbH, Berlin, Germany). Daily changes in P-wave and R-wave sensing were analyzed over 6 weeks. A breathing test (in- and expiration) was performed in two different body positions at baseline and during a 6-week in-house follow-up to investigate alterations of P-wave and R-wave sensing.

RESULTS

R-wave amplitude and the high P-wave visibility (94.4%) remained unchanged during the follow-up period. In most patients both an increase and decrease of R-wave amplitude, and in some cases a complete R-wave vector change (31.6%), was documented during the "breathing test." Change of body position did not alter R-wave sensing amplitude mostly. "Breathing test" and change of body position had no effect on P-wave sensing performance. In 15.8% of the patients, misclassification of episodes as AF or high ventricular rates due to P-wave oversensing occurred. No ILR-related complication occurred. Automatic transmission via BIOTRONIK Home Monitoring® was successful 100% of the time.

CONCLUSION

This study demonstrates that the BioMonitor 2-AF is a safe and effective tool for continuous cardiac monitoring.

Maintaining Accurate Long-Term Sensing Ability Despite Significant Size Reduction of Implantable Cardiac Monitors

BACKGROUND

The Reveal LINQ™ implantable cardiac monitor (ICM; Medtronic, Minneapolis, MN, USA) is obviously smaller than its precursor (the Reveal XT™), but little is known about its long-term safety. Here, we investigated the long-term R-wave sensing reliability of the Reveal LINQ™ ICM.

METHODS

We analyzed the sensing quality of the Reveal LINQ™ ICM over time between March 2014 and January 2015.

RESULTS

A total of 30 patients underwent Reveal LINQ™ implantation. The main reason for implantation was unexplained syncope (60%). We evaluated a total of 305.8 patient-months (median, 10.7 months) of R-wave sensing quality. A comparison of baseline and follow-up R-wave sensing values revealed no difference (0.401 mV ± 0.244 mV vs 0.447 mV ± 0.323 mV; P = 0.225).

CONCLUSIONS

The consistent detection of events is an important safety feature of an ICM and linked to secure R-wave sensing. Despite the noticeable size reduction, the Reveal LINQ™ ICM retains reliable sensing quality over time.

R-wave sensing in an implantable cardiac monitor without ECG-based preimplant mapping: results from a multicenter clinical trial

INTRODUCTION

Reducing the form factor of an implantable cardiac monitor (ICM) may simplify device implant. This study evaluated R-wave sensing at a range of electrode distances and a preferred device implant location without mapping.

METHODS

Patients scheduled for a Medtronic Reveal® ICM implant (Medtronic Inc., Minneapolis, MN, USA) underwent a preimplant pocket recording using a diagnostic recording catheter. The ICM implant location was left to the discretion of the implanting physician, but a "recommended" position spanned the V2 -V3 electrocardiogram electrode location in an oblique 45° angle. R-wave amplitudes were analyzed from ICM follow-up.

RESULTS

Seventeen of 41 subjects (15 male, age 57 ± 16 years) had the maximum surface-filtered R-wave at the recommended location. Fourteen patients underwent diagnostic recording across the range of electrode spacing. There was a strong correlation between the R-wave amplitude and electrode distance (r(2) = 0.97, P < 0.001) with an increase of 29 μV per 2.5 mm. Comparing normalized R-wave distributions between the recommended ICM implant group (Group 1, n = 19) and the remaining patients (Group 2, n = 7), the proportion of ICM R-wave counts of amplitude 0.25-1.2 mV was higher (79% vs 46%, P < 0.05). Of 17 patients in Group 1 who had ≥ 1-month ICM follow-up (79 ± 45 days), no sensing-related false arrhythmia detection was found in 16 (93%) patients.

CONCLUSIONS

The subcutaneous R-wave amplitude correlates with electrode spacing in the implant zone of ICM patients. Implant locations at the V2 -V3 position at a 45° angle offer an adequate R wave for sensing. Preimplant mapping to achieve acceptable R-wave amplitude may not be necessary.