Undersensing by an ICD Due to Alternans of the Ventricular Electrogram

Heuverswyn, Frederic E. Van; Timmers, Liesbeth; Stroobandt, Roland X.; Barold, S. Serge

doi:10.1111/j.1542-474x.2012.00521.x

Cited by 6 publications

(9 citation statements)

References 10 publications

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“…Its effectiveness is supported by reports that T-wave oversensing can be corrected by inserting a new generator that combines these features, 39,40 but this is usually an unnecessarily expensive solution. Although these combinations usually are safe, rare cases of serious undersensing in VF have been reported, 38,41,42 There is no consensus as to if or when sensing during induced VF should be tested if these features are programmed, but it is prudent to do if the R wave is small.…”

Section: Parameter Combinations and Risk Of Undersensing In Vfmentioning

confidence: 99%

Troubleshooting Implanted Cardioverter Defibrillator Sensing Problems I

Swerdlow

Asirvatham

Ellenbogen

et al. 2014

Circ: Arrhythmia and Electrophysiology

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electrograms from floating bipolar atrial electrodes on defibrillation leads. 12,13 The former requires a dual-coil lead and the latter a specialized lead. Evaluating Sensing From ICD ElectrogramsFilter settings may influence electrogram appearance (Figure 2). Wideband signals with minimal filtering reproduce QRS complexes accurately and retain the distinctive, rounded appearance of T waves. Highly filtered narrowband signals display the signal that is compared with the sensing threshold in the sensing process, but they alter signal amplitude and polarity, markedly reducing the amplitude of signals with prominent low-frequency components, such as T waves and some components of VF ( Figure I in the Data Supplement). Programmable filter settings (St. Jude Medical and Biotronik) permit assessing the effect of filtering on R-and T-wave amplitude.Sampling is the process of converting an analog signal into a digital sequence. It must be performed at ≥2× the source's signal frequency to reproduce the source's information content completely. ICD telemetry reproduces cardiac signals completely because it samples at 128 to 256 Hz per channel, but it may distort nonphysiological signals periodically (Figure II in the Data Supplement) 14 and it may not completely reproduce myopotentials that have frequency content >100 Hz. Stored Versus Real-Time ElectrogramsStored electrograms and their corresponding interval and episode data are the primary sources for diagnosing devicedetected tachycardias. Real-time electrograms are useful in troubleshooting reproducible oversensing: lead or connector problems in the pocket may be identified by pocket manipulation, pectoral or diaphragmatic myopotentials can be provoked by pectoral muscle contraction and straining or deep breathing, respectively (Figure III in the Data Supplement). Differential electrograms recorded simultaneously between 1 common electrode and 2 different electrodes are useful when lead or connector-related oversensing is suspected (Figure 3). Role of Additional Diagnostics, Alerts, and Remote MonitoringTrend plots of P-and R-wave amplitude, impedance measurements and trends, and algorithms that identify oversensing facilitate electrogram interpretation as discussed below. Alerts for suspected oversensing may notify the patient using audible tones or pulse generator vibration, may be transmitted via internet-based remote-monitoring networks, or both. Remote monitoring has transformed follow-up of sensing problems, permitting rapid determination of cause of an alert and implementation of a response plan, especially for devices with wireless telemetry.16,17 Troubleshooting Ventricular OversensingPresentation, Classification, and Recognition Clinical PresentationIn ICD patients, ventricular oversensing of rapid signals presents as oversensing alerts or inappropriate detection of VT/ VF, often resulting in inappropriate shocks. In pacemakerdependent patients it also presents as failure to deliver bradycardia pacing. ClassificationOversensing can be classified by electro...

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Section: Parameter Combinations and Risk Of Undersensing In Vfmentioning

confidence: 99%

Troubleshooting Implanted Cardioverter Defibrillator Sensing Problems I

Swerdlow

Asirvatham

Ellenbogen

et al. 2014

Circ: Arrhythmia and Electrophysiology

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“…One case (previously reported) exhibited simultaneous alternans of the RV EGM, FF EGM, and the surface ECG (Fig. ) …”

Section: Resultsmentioning

confidence: 67%

“…) . Five patients presented with ischemic cardiomyopathy (including two patients previously reported) and three had nonischemic cardiomyopathy. This patient (Case 9, Fig.…”

Section: Resultsmentioning

confidence: 72%

“…We found seven new cases of QRS alternans and added two of our previously reported examples for data analysis (Table and Figs. ) . Five patients presented with ischemic cardiomyopathy (including two patients previously reported) and three had nonischemic cardiomyopathy.…”

Section: Resultsmentioning

confidence: 80%

“…QRS alternans is usually precipitated by changes in heart rate; input from nervous, humoral, pharmacologic components; or ectopic beats. This report describes our observations of QRS alternans documented in nine patients with an implanted cardioverter‐defibrillator (ICD; seven new cases and two previously published cases by our group for comparison) …”

Section: Introductionmentioning

confidence: 87%

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Alternans of the Ventricular Electrogram in Patients with an Implanted Cardioverter-Defibrillator

Barold

M.Sc.

Meester

et al. 2015

Pacing and Clinical Electrophysiology

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Ventricular alternans may be more common than realized in ICD patients with VT. The correlation of VEGM alternans with the surface electrocardiogram remains unknown. Although QRS alternans itself as an electrical pattern is generally benign, its cause may not be, as illustrated in our patient with CPVT. Furthermore, associated cycle length alternans or undersensing of the smaller alternans component may complicate ICD therapy.

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