Course sheet · 48 cases
Case table
Every case of the book with its device printout. Hover over a blurred cell to show the true diagnosis, the steps of the recording or the clinical pearl; on a touch screen, tap it.
Printouts are the LATITUDE™ / ZOOM™ reports the cases were drawn from; the patient’s name and full date of birth are covered. “Book p.” gives the case’s pages in the printed book (paperback, English edition).
One teaching day
9:00–17:00, 2 h of breaks, 7.5–18 minutes per case: the 26 cases in bold, the most important of each chapter.
- 09:00–10:30 1 · Counters (5 × 18 min) 1-1 1-2 1-3 1-7 1-8
- 10:30–11:00 Coffee break
- 11:00–12:30 2 · Therapies (5 × 18 min) 2-6 2-7 2-10 2-11 2-15
- 12:30–13:30 Lunch
- 13:30–15:30 3 · Discrimination (8 × 15 min) 3-1 3-2 3-4 3-5 3-6 3-7 3-10 3-11
- 15:30–16:00 Coffee break
- 16:00–17:00 4 · Oversensing (8 × 7.5 min) 4-1 4-3 4-4 4-5 4-6 4-7 4-8 4-9
| # | Case | Fig. | Book p. | True diagnosis | Steps | Clinical pearl | |
|---|---|---|---|---|---|---|---|
| 1-109:00 | Detection and treatment of a VF episodesame printout as 2-1 | 10–17 | VF — appropriate shock | ICM, CRT-D, 1 coil. SR + BiV pacing → fast PVT (2 VT cycles, then VF) → V-Epsd: 8/10 VT zone (2 VT + 6 VF) → 8/10 VF zone: VF duration (5 s) overrides VT → V-Detect → charge ≈10 s (a few undersensed beats, 6/10 kept) → end of charge: 135 ms refractory, 1st beat uncounted, 2/3 fast after the 500 ms window → 41 J synced to R (HVI 76 Ω) → 500 ms post-shock refractory → SR. | An episode starts with 3 consecutive fast cycles, then 8/10 fast (V-Epsd); 6/10 must hold through the duration. Durations: initial, post-detection (VF zone fixed at 1 s), post-shock. | ||
| 1-209:18 | Detection and treatment of a VT episode | 18–23 | MMVT — appropriate ATP | ICM, CRT-D. AS + BiV → regular MMVT w/ AVD → V-Epsd after 8/10 VT, VT initial duration 12 s → V-Detect, V>A true → burst of 8 pulses (BiV) → SR. | Probabilistic counters (8/10 to detect, 6/10 during the duration) suit VF, where low, variable signals are partly undersensed, as well as regular VT where every cycle is sensed. | ||
| 1-309:36 | Non-sustained ventricular tachycardia | 24–29 | NSVT — no therapy | DCM, CRT-D, frequent NSVT. AS + BiV → MMVT w/ AVD, VT cycles alternating with PVC-classified beats → 3 consecutive VT cycles open the 8/10 search → V-Epsd (8/10 VT), 12 s duration starts → spontaneous termination → 5 slow cycles: 6/10 lost → V-EpsdEnd 10 s later, no Rx. | Long initial durations (VT zone 12 s, VF zone 5 s) or high zones let NSVT stop on its own; the episode then ends when 8/10 is not met again for 10 s (no therapy delivered). | ||
| 1-4 | Change of detection zone | 30–35 | VT accelerating into VF zone — ATP then shock | ICM, CRT-D. AS + BiV → MMVT w/ AVD, VT-zone then VF-zone cycles → V-Epsd VT (5 VT + 3 VF), VT initial duration 2.5 s → 8/10 VF, VF duration starts → VT duration ends but VF 6/10 still valid: VT Rx held → 5 VT cycles: VF 6/10 lost → burst (1st VT Rx) fails → redetection 8/10 VT and VF, post-redetection 1 s each → VT V-Dur, VF still running → VF duration ends → charge → divert window → 41 J on 2nd fast cycle → SR. | Each zone has its own 8/10 window and duration, running in parallel; after ATP for VT, acceleration into the VF zone gets the 1 s VF redetection, not the long initial duration. | ||
| 1-5 | Spontaneous termination and shock diversionpatient 2 only (no 5a) | 36–42 | Self-terminating polymorphic VT — charge diverted | Pt 1, VR ICD: PVT → V-Epsd VT-1 (8/10) → 8/10 VT then VF, durations → end of VF duration → ATP QC fails → charge → spontaneous termination → 6/10 lost → charge diverted. Pt 2, DR ICD: same; PVC in the V noise window after AP ([VS]) → ATP QC fails → charge → termination → end of charge, 500 ms window, 1st beat uncounted (135 ms) → 2 of 3 slow → charge diverted. | "Shock not reconfirmed" Off: charging stops on 5 slow beats out of 10 (6/10 lost). On: once charging starts, the shock is always delivered (first R wave after 500 ms). | ||
| 1-6 | Diversion window at end of a charge | 43–47 | VF (+ AF) — appropriate shock | ICM, CRT-D, pAF. AF + BiV → very fast PVT in VF zone → V-Epsd (8/10 VF), initial duration → V-Detect → charge 11 s (max output) → end of charge: 135 ms refractory, 1st beat uncounted → next 2 VF beats fall inside the 500 ms divert window → shock synced to the 3rd fast beat (41 J, 64 Ω) → VF + AF end → 500 ms post-shock, 1st A and V beats uncounted. | After charge end comes a 500 ms diversion window (its first 135 ms refractory); a reconfirmed shock needs 2 of the next 3 intervals faster than the lowest zone; 500 ms refractory after any shock. | ||
| 1-709:54 | Undersensing and charge diversion | 48–53 | Induced VF with undersensing — diverted, then shock | Brugada, VR ICD, septal lead (R 3.5 mV), induction at 1 mV: low-energy T-wave shock after 8 pulses at 200 bpm → low-voltage PVT/VF → V-Epsd (8/10 VF) → 1st V event undersensed → 1 s duration, V-Detect, charge → end of charge: undersensing, 2/3 fast not met → Dvrt (false “termination”) → new 8/10, post-detection duration → V-Detect → very short charge (capacitors still charged) → not reconfirmed (2nd charge of an episode is never diverted) → 21 J → SR. | AGC: after refractory + 15 ms the threshold drops to 75% of the last peak (mean peak if paced), then 7/8 per step down to Min or the programmed value; only one charge per episode can be diverted. | ||
| 1-810:12 | End-of-episode criteria following an electric shock | 54–67 | VF — 3 shocks; end-of-episode criteria | ICM, CRT-D. AP + BiV → VF → VF duration 5 s → charge → 41 J on 2nd fast beat → VF restarts at once → redetection 8/10 VT (1 s) and VF (post-shock 1 s, fixed) → V-Detect → charge → 2nd shock after 500 ms, the 30 s end-of-episode clock starts → recurrence <30 s = same episode → shock → SR … later VF: V-EpsdEnd (30 s without 8/10, counters reset) → new episode: 8/10 VT + VF → ATP QC (1st Rx of a new episode) fails → shock → recurrence → 1 s post-shock duration → shock → SR. | V-Epsd End when 8/10 is not met again for a fixed time: 10 s after no therapy or ATP only, 30 s after any shock. 8/10 within it = same episode: 1 s post-shock duration, next shock. | ||
| 2-1 | VF episode correctly detected and treated with maximum output shocksame printout as 1-1 | 70–77 | VF — appropriate shock | ICM, CRT-D. SR + BiV → fast PVT (1 VT, then VF) → V-Epsd 8/10 VT (1 VT + 7 VF) → 8/10 VF, VF duration 5 s takes precedence → V-Detect → charge ≈9 s (a few RVS undersensed, too sparse to divert) → 135 ms, 1st beat uncounted, 2/3 fast after 500 ms → 41 J on 2nd beat (54 Ω) → no beat: V pacing 2 s after the shock → SR. | Up to 8 shocks in the VF zone; shocks 3 to 8 are always 41 J. Maximum energy from the first shock is reasonable (IIa) unless a lower energy proved effective at induction. | ||
| 2-2 | VF episode with low-amplitude shock in a child | 78–82 | VF in a child — low-energy shock | 13-y/o post-SCA, VR ICD, recurrent VF. SR (VS) → very fast PVT, every beat in VF zone → V-Epsd (8/10 VF), initial duration programmed at 1 s → charge 2.7 s → 135 ms + uncounted beat, then 2 fast (VF, VT) after 500 ms → 14 J synced (33 Ω) → SR. | Children: first shock about 1 J/kg (2-5 J in neonates), usually one high VF zone, close remote monitoring; inappropriate therapies are commoner (lead fracture, sinus tachycardia, TWOS). | ||
| 2-3 | Multiple electric shocks in the VF zone | 83–94 | VF — 5 max-output shocks | ICM, CRT-D. Slow VT → accelerates into VF zone → end of duration, charge → degenerates into VF → 41 J on 2nd fast beat → organized VT restarts → redetection 8/10, VF 1 s → charge → shock after 500 ms (no 2/3 check after a shock) → VT/VF again → same sequence → shocks 3, 4, 5 (41 J each) → termination. | A high DFT seen in spontaneous VF is an emergency. Programmable: energy, vector and polarity (biphasic, tilt fixed). With a single-coil lead only RV coil → can delivers a shock. | ||
| 2-4 | VT in the VF zone and high defibrillation thresholdpaper book (EN): item 4 has no badge on the trace; from badge 4 on, badge n = item n+1 | 95–105 | MMVT degraded to VF by shock — high DFT | ICM, DR ICD. Organized VT in VF zone → 8/10 VT then 8/10 VF; VT duration ends, VF still running → VF duration ends → ATP QC fails → charge → 41 J → 2 slow beats then very fast disorganized VF → 1 s redetection → 2nd shock → same pattern (shock, 2 slow beats, VF) → 3rd, 4th shock → slow VT persists. High DFT: CS coil added. | The DFT is not a fixed value: a shock can turn stable VT into VF and repeated maximum shocks may fail; an extra coil (e.g. coronary sinus) widens the shock field. | ||
| 2-5 | VF, device shock with AF induction | 106–112 | Fast VT — appropriate shock, shock-induced AF | ICM, DR ICD. Fast VT w/ AVD in VF zone → V undersensing but 6/10 kept → ATP QC fails → charge → 41 J → VT ends → A beat sensed in refractory → A pacing in the atrial vulnerable period → AF induced. | Ventricular shocks are synchronized to the R wave whatever the atrial phase and can induce AF, more often with low energy and dual-coil shocks; induced AF is usually short. | ||
| 2-611:00 | ATP burst in the VF zone | 113–126 | Recurrent MMVT in VF zone — ATP QC then shocks | DCM, DR ICD. SR → MMVT in VF zone → 8/10 VF, 1 s duration → V-Detect, rate (last 4 cycles) 229 <250 → ATP QC (8-pulse burst) → 1st beats uncounted, 2 of 3 slow → charge diverted → V-EpsdEnd → same VT recurs → ATP QC → 2/3 fast → charge → 41 J on 2nd fast beat → SR → VT recurs <30 s (same episode) → no 2nd ATP QC (1 per episode) → charge → 41 J → SR. | ATP first (a burst rather than a ramp, class I) up to about 230 bpm cuts shocks; after the burst, 2 of 3 fast intervals start the charge, 2 of 3 slow or a 2 s pause divert therapy. | ||
| 2-711:18 | ATP burst in the VF zone with acceleration | 127–132 | MMVT accelerated by ATP QC — shock | Severe CM, perm. AF, CRT-D. MMVT in VF zone → 8/10 VF, 1 s duration → V-Detect, rate 226 <250 → ATP QC (8 pulses, 88 % coupling) → 1st beat in refractory ([VS]), 2nd uncounted → 2/3 fast → charge → VT accelerates (fast, low voltage) → end of charge, 500 ms window → 31 J on 2nd fast beat → SR. | ATP Quick Convert (VF zone, before charging, up to 250 or 300 bpm) is a fixed burst of 8 at 88%; if it fails or accelerates the arrhythmia, the shock comes later and succeeds less often. | ||
| 2-8 | Undersensing, rate calculation error and ATP burst in the VF zone | 133–138 | PVT/VF with undersensing — futile ATP QC, shock | Idiopathic VF, DR ICD. AP (sensor rate) + VS → very fast PVT → undersensed beat classified VS → V-Detect: rate over the last 4 cycles 225 <250 (falsely low) → ATP QC, no V capture → charge → shock on the 3rd VF beat (the 2nd falls inside the 500 ms window) → 41 J → SR. | The rate that allows ATP is the mean of the 4 cycles before V-Detect, so undersensing can let ATP fire in fast VF; evidence for ATP above 250 bpm is weak. | ||
| 2-9 | Oversensing and anti-tachycardia pacing in the VF zone | 139–144 | Lead noise (oversensing) — inappropriate ATP | ICM, DR ICD (box change, old RV lead). AP-Sr/VP-Sr → noise of variable amplitude on V sense, shock EGM clean → VF counter fills (V-Epsd) → intermittent: at end of duration rhythm = sinus, no Rx → noise again → VF counter → ATP QC (2 of 8 pulses capture) → noise persists, 2/3 fast → charge → noise stops: 6/10 lost → charge diverted → noise resumes → VT counter (V-Detect) → ATP, no capture. | Lead noise can trigger very fast inappropriate ATP; systematic ATP up to 300 bpm is unproven and can be pro-arrhythmic when inappropriate. | ||
| 2-1011:36 | Anti-tachycardia pacing in the VT zone | 145–149 | MMVT — ATP success | CRT-D. AS + BiV → MMVT w/ AVD in VT zone → V-Epsd (8/10 VT/VT-1) → initial duration 12 s → V-Detect, V>A → burst of 10 pulses (BiV) → SR. | ATP terminates about 90% of VTs below 200 bpm and works up to about 240 bpm; sequences can be programmed empirically, sparing shocks, symptoms and battery. | ||
| 2-1111:54 | Anti-tachycardia pacing in the VT zone and post-detection duration | 150–160 | VT — multiple ATP sequences | CRT-D. AS + BiV → MMVT w/ AVD → V-Epsd, 12 s → V-Detect (V>A) → burst of 10 → SR → same VT before V-EpsdEnd → 8/10, post-detection duration 1 s → 2nd burst (same episode) → works, quick recurrence → bursts 3, 4 → ramps 1–3 (−10 ms per pulse, min 200 ms) → NSVT, 8/10 not met. | VT recurring before V-Epsd End gets the VT-zone redetection duration (here 1 s) and is paced after a few cycles: lengthen it (programmable in the VT zone only) to let NSVT stop. | ||
| 2-12 | Progression of therapies in the VT zone | 161–173 | VT — ATP then 11 J shock | CRT-D. AS + BiV → MMVT w/ AVD → V-Epsd, 12 s → V-Detect (V>A) → burst 1 fails → 8/10, 1 s → burst 2 fails → bursts 3, 4 → ramps 1, 2 → ramp 3 works → VT recurs before V-EpsdEnd (same episode) → ramp 4 → next Rx = shock: charge → 11 J on 2nd fast beat after the divert window (2/3 fast) → SR. | Recurrence before V-Epsd End moves on to the next therapy in sequence. Burst settings: 5-15 pulses, coupling around 88%, a minimum interval limit, 5 V / 1 ms output. | ||
| 2-13 | Low-amplitude shock and acceleration of arrhythmia | 174–185 | VT — low-energy shock accelerates, 41 J shock | CRT-D. MMVT w/ AVD in VT zone → burst 1 (8 pulses) fails → burst 2 (+1 pulse) → bursts 3, 4 → ramps 1–3 → next Rx = shock: charge → 11 J on 2nd fast beat (2/3) → VT accelerates into VF zone → VF detection, charge → 41 J → SR. | A first VT-zone shock of 10-15 J charges quickly and often works, but can accelerate the VT (upper limit of vulnerability). | ||
| 2-14 | Maximum output shock in the VT zone | 186–194 | VT — ATP fails, max shock | VR ICD. Probable VT (morphology change on the shock EGM) → end of duration: burst of 10 fails → bursts 2, 3 → ramps 1–3 → next Rx = shock: charge → 41 J on 2nd fast beat after the divert window (2/3 fast) → SR. | A first VT-zone shock at maximum energy lowers the pro-arrhythmic risk and raises first-shock success, at the cost of a longer charge. | ||
| 2-1512:12 | Anti-tachycardia pacing in the VT zone with acceleration into the VF zone | 195–210 | VT — ATP accelerates into VF zone, shock | CRT-D. VT w/ AVD in VT zone → end of duration: burst of 10 → VT accelerates into VF zone → VF detection, charge → becomes polymorphic → 41 J → SR. | ATP accelerates VT or degenerates it into VF in about 1-5% of cases: shocks must always be programmed as back-up. | ||
| 3-113:30 | Single-chamber discrimination, Rhythm ID and a ventricular tachycardia episode | 211–216 | VT — appropriate ATP (RID−) | ICM, VR ICD, RID thr 94 %. Abrupt, stable tachycardia >200 bpm, shock-EGM morphology ≠ SR → every beat uncorrelated (U, 0 %) → V-Epsd (8/10 VT), 12 s → V-Detect: RID− (0/10 correlated, <3/10) → VT → burst → SR. | Boston discriminators act only in VT/VT-1 zones (VF zone: rate alone). Program them only if conducted SVT is possible; judge them by sensitivity for VT (near 100%) and specificity. | ||
| 3-213:45 | Single-chamber discrimination, Rhythm ID and an atrial fibrillation episode | 217–221 | AF — therapy correctly withheld (RID+) | HCM, VR ICD, RID 94 %. Irregular tachycardia, narrow shock EGM; VT-1/VS alternate, every beat correlated (C) → V-EpsdEnd of a previous episode (8/10 not met) → V-Epsd (8/10 VT-1) → V-Dur: RID+ (≥3/10 correlated) → SVT, Rx withheld; beat-by-beat analysis goes on. | Rhythm ID compares 8 points of the shock-channel QRS with a sinus template: 3 or more of 10 cycles correlated = SVT (RID+, therapy withheld), fewer = VT (RID-); VF-zone cycles never correlate. | ||
| 3-3 | Single-chamber discrimination, Rhythm ID and sinus tachycardia | 222–226 | Sinus tachycardia — therapy correctly withheld (RID+) | ICM, VR ICD, RID 94 %. Regular tachycardia, narrow shock EGM, gradual acceleration VS → VT-1, every beat correlated → V-EpsdEnd (previous episode) → V-Epsd (8/10 VT-1) → V-Dur: RID+ → Rx withheld → rate slows (VS), still correlated. | The template is refreshed passively (every 2 h) or actively (every 28 h, pacing modified); at follow-up, check that the match stays well above the threshold (nominal 94%). | ||
| 3-414:00 | Single-chamber discrimination, Rhythm ID and correlation percentage | 227–237 | Sinus tachycardia — inappropriate therapies (RID threshold too high) | ICM, VR ICD, RID 94 %. Regular narrow tachycardia, gradual acceleration VS → VT-1, correlated → VT-1 duration ends (no Rx in VT-1) → faster, VT zone: RID+ → withheld → V-Detect: only 2/10 correlated → RID− → “VT” → inappropriate burst → redetection: no morphology analysis after a Rx → every VT-zone Rx delivered. Fix: lower the 94 % threshold (83 %: sens 100 %, spec 79 %). | Nominal RhythmMatch 94%: 100% sensitivity but about 41% specificity (morphology checked at initial detection only); 83% kept 100% sensitivity and raised specificity to 79%. | ||
| 3-514:15 | Single-chamber discrimination, Rhythm ID and SRD | 238–248 | AF — inappropriate shocks (SRD expired) | ICM, VR ICD, RID 94 %. Irregular narrow tachycardia (AF), VT-1/VS alternate, correlated → V-EpsdEnd (previous) → V-Epsd (8/10 VT-1/VT) → V-Dur: RID+ → withheld → SRD timer expires (SRD marker) → VT-zone Rx despite RID+ → successive Rx up to 5 shocks. Fix: SRD Off or several minutes. | SRD delivers therapy after a set time even when discriminators say SVT; guidelines advise turning it off or setting it to several minutes. | ||
| 3-614:30 | Dual chamber discrimination and V>A | 249–253 | VT with AV dissociation — appropriate ATP (V>A) | ICM, CRT-D. AS + BiV → abrupt regular tachycardia w/ AVD (V 156 > A 62 bpm) → V-Epsd: beats uncorrelated (U, <94 %) → V>A true (V ≥10 bpm faster over the last 10 intervals) → VT (V>A overrides RID) → V-Detect → burst → SR. | V>A (mean of the last 10 V vs 10 A intervals, at least 10 bpm faster) overrides every other discriminator: True = VT, therapy. | ||
| 3-714:45 | Dual-chamber discrimination, atrial refractory periods and V>A criterion | 254–263 | Sinus tachycardia — inappropriate ATP (false V>A) | ICM, DR ICD, RID. Probable 1:1 ST, VS/VT-1 alternate → 8/10 met → end of duration: stable + correlated → no Rx → beat by beat: R-wave timing varies → “unstable”, still correlated → stable again → PAC → 2nd PAC falls in the A refractory period after V sense (long PR) → not counted → false atrial slowing → V>A true (overrides RID) → bursts 1–5, inappropriate → sinus rate falls below VT-1 → end. | Undersensed atrial events (an atrial extrasystole in the refractory period) can make V>A falsely True and override correct morphology; V>A needs good atrial sensing, otherwise turn it off. | ||
| 3-8 | Dual-chamber discrimination and tachycardia | 264–269 | Sinus tachycardia — therapy correctly withheld | DCM, DR ICD, RID + atrial discrimination On. Probable conducted ST, VS → acceleration into VT-1 → correlated (>94 %) → V-Epsd (8/10 VT-1) → end of duration: V>A false → RID+ (all correlated) → withheld → slows to VS. Logic: step 1 V>A, step 2 RID, step 3 AFib/stability. | Dual-chamber Rhythm ID works in steps: V>A first (True = VT), then morphology (3 or more of 10 correlated = SVT), then stability and the AFib rate threshold. | ||
| 3-9 | Dual-chamber discrimination and atrial tachycardia | 270–274 | Atrial tachycardia — therapy correctly withheld | ICM, DR ICD, RID. Probable AT w/ variable AV conduction, VS/VT alternate, correlated → V-Epsd (8/10 VT) → end of duration: V>A false, RID+ → SVT, withheld → rate slows (VS), 6/10 VT lost. | 1/1 atrial tachycardia or flutter fools onset and stability (abrupt and stable, like VT); morphology-based Rhythm ID is preferred in these patients. | ||
| 3-1015:00 | Dual-chamber discrimination and dual tachycardia | 275–279 | Dual tachycardia (AF + VT) — appropriate ATP | Mitral CM, DR ICD. AF w/ fast irregular conduction → sudden regular V rhythm, new EGM morphology (VT) → 3 consecutive VT cycles: atrial intervals classed against the AFib threshold → V-Epsd (8 consecutive VT) → 10 cycles to V-Detect: correlation → V>A false, RID− → AF+ (6/10 then 4/10 fast A) + stable → dual tachycardia → treat → burst of 10 fails → V-Detect on rate only (no discrimination after a Rx) → 2nd burst → VT ends, AF goes on. | With V>A false and morphology uncorrelated, stability and the AFib rate threshold decide: stable, or no fast atria → therapy; unstable with fast atria → inhibition. | ||
| 3-1115:15 | Dual-chamber discrimination and AF with aberrant conduction | 280–282 | AF/AT with aberrancy — therapy correctly withheld | ICM, DR ICD. Fast atrial activity (probable AT/AF) w/ fast variable conduction, VS/VT/VF cycles → V-Epsd (8/10) → end of duration: V>A false, RID− (aberrancy), AF+ (A rate > AFib threshold), unstable (>30 ms) → SVT (aberrantly conducted AF) → withheld → beat by beat, same diagnosis. | Dual tachycardias and AF with aberrancy are the hardest: V>A cannot decide; with uncorrelated vectors and fast atria, stability makes the call (stable = VT). | ||
| 3-12 | Dual-chamber discrimination and discrimination error due to signal variability on the shock channel | 283–290 | SVT — inappropriate ATP + 6 shocks | HCM, DR ICD. Regular 1:1 tachycardia (AS-VS) → A (AF) + V (VT) acceleration → V-Epsd (8 VT); shock-EGM signal variable (myopotentials) → end of duration: V>A false, stable, AF+, RID+ → withheld → still RID+ → shock-EGM noise: RID− + AF+ + stable → “dual tachycardia” → 1st Rx → redetection (no discrimination) → every VT-zone Rx (ATP + 6 shocks). | Morphology is read on the shock channel: myopotential noise there decorrelated SVT cycles and caused inappropriate therapy. | ||
| 3-13 | Dual-chamber discrimination and discrimination error due to inappropriate programming of the correlation percentagetwo episodes | PDF a PDF b | 291–297 | 1:1 atrial tachycardia — inappropriate ATP (RID threshold too high) | ICM, CRT-D, RID 94 %. Ep 1: regular 1:1 tachycardia, 1st fast beat atrial (AT) → V-Epsd (8 VT/VF), correlated → end of duration: stable, AF+, RID+ → withheld → RID− (<3/10 correlated) → “dual tachy” → burst → ends. Ep 2: same 1:1 AT → end of duration: RID−, stable → bursts/ramps → V stops spontaneously. Fix: threshold 88 %. | A correlation threshold set too high misclassified atrial tachycardia; 88% would have prevented the inappropriate therapies. | |
| 3-14 | Dual-chamber discrimination, atrial tachycardia | 298–300 | 1:1 atrial tachycardia — therapy withheld (gradual onset) | ICM, wide QRS, CRT-D, Onset/Stab. Fast 1:1 rate at the VT-zone edge (RVS) → slight acceleration into VT zone (<375 ms) → 8/10; onset gradual (Gradl) → end of duration: stable + gradual → Rx withheld (read as ST) → beat by beat: still stable, withheld. True dx 1:1 AT; fix: raise the VT zone or use RID. | Onset (lowest zone only) withholds therapy for a gradual rate rise; 1/1 AT hovering at the zone limit defeats it: raise the VT zone above the clinical AT or rely on morphology. | ||
| 3-15 | Dual-chamber discrimination and atrial fibrillation | 301–308 | Conducted AF — inappropriate ATP + shock (stability) | ICM, CRT-D, Onset/Stab, stability thr 20 ms. Irregular conducted AF → V-Epsd (Gradl) → end of duration: AF+ and unstable → withheld → conducted AF stabilises → “stable” → bursts → ramps → max shock, all inappropriate → the shock ends AF. Fix: stability 30–40 ms. | Conducted AF can stabilize and pass the 20 ms nominal stability criterion; tune stability and the AFib rate threshold (170 bpm nominal; too low risks therapy for sinus tachycardia). | ||
| 3-16 | Dual chamber discrimination, atrial tachycardiatwo episodes | PDF a PDF b | 309–315 | 1:1 atrial tachycardia — ATP (Onset/Stab) vs withheld (RID) | ICM, CRT-D. Ep 1 (Onset/Stab): regular 1:1 tachycardia, A beats classed AF → V-Epsd (Gradl) → end of duration: AF+ and stable → burst (inappropriate) → SR. Ep 2 (RID): identical 1:1 AT → V-Epsd → end of duration: RID+ → withheld → spontaneous termination (favours AT). | Onset/Stability handles 1/1 AT poorly (fast atria and a stable rhythm mean therapy); the same tachycardia may be inhibited another time: programming is a trade-off. | |
Discrimination rules (Boston Scientific)Discrimination works only in the VT zones (VT, VT-1), at the end of the initial duration; in the VF zone rate alone decides. After a first therapy, redetection is on rate only (no discrimination). SRD (sustained rate duration) treats despite an SVT verdict once its timer expires: usually Off (3-5). Single chamber: Rhythm ID only
Dual chamber: Rhythm ID (in steps)
Dual chamber: Onset/Stability
Guidelines: program discrimination up to 230 bpm; turn it off in complete, permanent AV block. | |||||||
| 4-116:00 | Oversensing of electrocautery | 318–321 | Electrocautery EMI — no therapy (Monitor only) | ICM, CRT-D, box change, Tachy Mode Monitor only. AS + BiV → electrocautery: fast, chaotic signals of variable amplitude on A, V and shock channels at once (AF, VF markers) → VF-zone episode, no Rx → stops → recurs. Rules: Tachy Off during surgery; asynchronous pacing if dependent; bipolar cautery, short bursts. | Electrocautery: fast, chaotic signals on all 3 channels. Set Tachy Mode off during surgery (asynchronous pacing if dependent); bipolar cautery, short bursts, plate far from the device. | ||
| 4-2 | Surgical intervention and VF at the time of reperfusiona = patient 1, b = patient 2 | PDF a PDF b | 322–328 | EMI + cardioplegia; true VF at reperfusion — shock | Pt 1 (AVR, CPB, Monitor only): no A/V activity (cardioplegia asystole despite pacing), baseline noise → cautery: fast chaotic signals on 3 channels (AF/VF) → VF zone, no Rx. Pt 2 (CABG, Monitor + Therapy): cautery on V + shock channels → stops → true very fast low-voltage VF at reperfusion (imperfect sensing) → detection, charge → 41 J → SR. | Cardiac surgery: cardioplegia shows as asystole despite pacing, VF is frequent at reperfusion. Usual practice: Tachy Mode off, temporary pacing and external defibrillation. | |
| 4-316:08 | Inappropriate therapies during a TAVI procedure | 329–333 | Oversensed pacing artefacts during TAVI — inappropriate ATP | CRT-D, TAVI. AS + BiV → temporary RV rapid pacing: sharp spikes on A, V and shock channels (artefacts, capture seen on the shock EGM) → VT/VF cycles alternate: 8/10 VT met, VF not → end of VT duration → ATP sequences → next Rx = shock: charge → pacing stops, oversensing ends → 2/3 fast not met → charge diverted. Rule: deprogram Tachy for TAVI. | Rapid ventricular pacing during TAVI is oversensed: suspend ICD therapies; LATITUDE can flag 4 or more cycles of 160 ms or less as a non-physiological RV signal. | ||
| 4-416:15 | Lead fracture and multiple capacitor chargesa = follow-up reports, b = episodes | PDF a PDF b | 334–337 | RV lead fracture — no therapy | VR ICD, LATITUDE Z alert. Fast signals on the bipolar sense EGM, shock EGM clean → variable-amplitude noise, some saturating → episode in VT zone, no Rx → noise ends. Follow-up: pace Z jump >2000 Ω, shock Z stable, many NSVT; interval plot = cloud of very short cycles (near blanking) + slower ones → RV lead fracture. | Lead fracture: intermittent very short, variable cycles plus abnormal pacing impedance (above 2000 Ω) with stable shock impedance; remote monitoring catches it before shocks. | |
| 4-516:23 | Oversensing of the P wave by the defibrillation leadSVG strip, converted to PDF | 338–340 | P-wave oversensing — no therapy | CRT-D. ST → intermittent oversensing of atrial activity by the RV lead (P wave seen on the A channel) → beats classed VS/VT-1/VT/VF → 8/10 VT-1 → NSVT stored, no Rx. Causes: RV lead near the AV junction, coil in RA, integrated bipolar. | P-wave oversensing by the RV lead: displacement to the AV junction (R wave falls) or an integrated bipolar lead straddling the tricuspid valve; lower sensitivity (then check VF sensing) or revise the lead. | ||
| 4-616:30 | Oversensing of atrial activity by the defibrillation lead during an episode of atrial arrhythmia | 341–342 | AF oversensed by RV lead — pause (pacing-dependent) | DCM + CHB, DR ICD, integrated bipolar RV lead (coil = anode). AF correctly detected, mode switch, VP-Sr at sensor rate (dependent) → fast A activity oversensed on V sense (shock EGM: no V activity) → V pacing inhibited, near-pause (presyncope) → oversensing ends. Risk: inappropriate Rx + asystole. | In pacing-dependent patients, oversensed atrial arrhythmia inhibits ventricular pacing (asystole) as well as risking inappropriate therapy. | ||
| 4-716:38 | Early displacement of a right ventricular lead into the atrium | 343–348 | RV lead dislodged into RA, AF oversensed — inappropriate shock | CRT-D, day 1. A and RV sensing almost simultaneous, LV later (true V) → AF onset: very fast signals on A, sensed on RV too (intermittently) → sustained RV oversensing → 8/10 VF → end of duration, charge → 6/10 lost → charge diverted → 2nd charge (cannot be diverted) → after 500 ms: inappropriate 41 J → AF and oversensing stop. CXR: RV lead floating in RA; Rx Off until revision. | Early RV lead dislodgement into the atrium: AF was sensed as VF and shocked; suspend therapies until the lead is repositioned. | ||
| 4-816:45 | T wave oversensing | 349–352 | T-wave oversensing — inappropriate ATP, charges aborted/diverted | VR ICD, small R wave. SR with intermittent TWOS (R/T alternation) → prolonged TWOS → V-Epsd (8/10) → 1 s duration, charge → PVC + undersensed QRS → undersensing: charge interrupted → 8/10 again → end of duration: ATP QC (inappropriate) → TWOS gone: charge diverted. | T-wave oversensing (rare with Boston) alternates high-frequency R and low-frequency T signals; small R waves favour it, as the AGC then reaches high sensitivity quickly. | ||
| 4-916:53 | Oversensing of diaphragmatic myopotentials | 353–355 | Diaphragmatic myopotentials — no therapy | VR ICD, integrated bipolar at RV apex. Low-amplitude non-physiological signals (crescendo–decrescendo) on V sense only, shock EGM clean → 3 consecutive beats classed VF → EGM stored as an NSVT episode, no Rx. Clues: end of diastole, high auto-sensitivity, apical integrated bipolar lead. | Diaphragmatic myopotentials: low-amplitude, high-frequency noise on the sensing channel only, late in diastole at maximum sensitivity; commoner with integrated bipolar apical leads. | ||
No case matches.
Abbreviations
- -Sr
- paced at the sensor-indicated rate
- 8/10, 6/10, 2/3
- fast intervals out of the last 10 (to detect / to stay detected), fast beats out of 3 after a charge
- AF
- atrial fibrillation
- AS / AP, VS / VP
- atrial / ventricular sensed / paced event
- AT
- atrial tachycardia
- ATP QC
- ATP Quick Convert (ATP in the VF zone)
- AVC / AVD
- AV conduction / AV dissociation
- AVR / CABG
- aortic valve replacement / coronary bypass
- BiV
- biventricular pacing
- CHB
- complete heart block
- CPB
- cardiopulmonary bypass
- CS
- coronary sinus
- CT
- charge time
- CXR
- chest X-ray
- DCM / HCM / ICM
- dilated / hypertrophic / ischaemic cardiomyopathy
- DFT
- defibrillation threshold
- Dvrt
- charge diverted
- EMI
- electromagnetic interference
- Gradl
- gradual onset
- HVI
- shock (high-voltage) impedance
- MMVT / PVT
- monomorphic / polymorphic VT
- NSVT
- non-sustained VT
- Onset/Stab
- Onset/Stability discrimination
- PAC
- premature atrial complex
- PVC
- premature ventricular complex
- RID+ / RID−
- Rhythm ID correlated (SVT) / not correlated (VT)
- Rx
- therapy
- SCA
- sudden cardiac arrest
- SR / ST
- sinus rhythm / sinus tachycardia
- SRD
- sustained rate duration
- TAVI
- transcatheter aortic valve implantation
- thr
- threshold
- TWOS
- T-wave oversensing
- V-Epsd / V-Detect / V-Dur / V-EpsdEnd
- episode start (8/10) / detection at end of duration / end of duration / end of episode
- VR / DR ICD
- single- / dual-chamber ICD
- Z
- impedance
From Boston Scientific ICD — clinical cases by P. Bordachar, M. Strik, A. Thiyagarajah, S. Ploux. Published by Cardiocases.