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cardio.atrial_flutter.wpw-preexcited.v1

Pre-excited atrial flutter (WPW) — DCCV / procainamide; AV-nodal blockers ABSOLUTELY contraindicated

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Start encounter →Print handoutPRODUCTION

Phase E variant of cardio.atrial_flutter.v1 — narrowed to pre-excited atrial flutter/AF conducting antegrade over a manifest accessory pathway in WPW. Because the accessory pathway is non-decremental, rapid antegrade conduction can degenerate to VF — the principal sudden-death mechanism in WPW. KEY DIFFERENCES FROM PARENT: AV-nodal blocking agents (adenosine, IV diltiazem/verapamil, beta-blockers, digoxin, and IV amiodarone) are ABSOLUTELY CONTRAINDICATED — they can preferentially accelerate antegrade accessory-pathway conduction and precipitate VF, inverting the parent flutter rate-control paradigm. Default acute therapy is electrical: immediate synchronised DC cardioversion if unstable (and preferred even in many stable patients given VF risk); stable-patient pharmacologic option is an accessory-pathway-prolonging agent — IV procainamide (first-line) or IV ibutilide — never an AV-nodal blocker. The broad, irregular, very fast QRS with a short shortest-pre-excited RR (<250 ms) is the diagnostic + risk signature, distinguished from polymorphic VT and SVT-with-aberrancy. Definitive therapy is accessory-pathway catheter ablation (Class I after a pre-excited AF/flutter event) — curative and substrate-eliminating; sports/occupational clearance only after cure or reassuring EP risk stratification. Manifest pointer reuses cardio.atrial_flutter.v1 manifest. Design-brief pointer reuses parent (pre-excitation-specific differences documented inline). Lifelong AV-nodal-blocker avoidance flag until the pathway is ablated. Status INTEGRATED. Authored 2026-05-15 by shard-06-cardio-acute as pre-excited (WPW) atrial-flutter variant. Sister-differentiated from parent flutter, with-cardiogenic-shock, and post-arrest shockable-rhythm.

Entry points (6)

  • symptom
    Palpitations, presyncope or syncope in a patient with known WPW / a delta wave on prior ECG — pre-excited atrial flutter/AF until proven otherwise (VF risk)
    palpitations_syncope_with_known_wpw
  • vital_abnormality
    Very fast (>200-250 bpm), broad-complex, often irregular tachycardia — pre-excited atrial flutter/AF; distinguish from polymorphic VT and SVT with aberrancy
    very_fast_broad_irregular_tachycardia
  • imaging
    ECG showing flutter/fibrillatory atrial activity conducting with variable broad pre-excited QRS morphology — antegrade accessory-pathway conduction
    ecg_pre_excitation_with_atrial_flutter
  • vital_abnormality
    Hypotension / shock / pulmonary oedema / ischaemia with a wide irregular tachycardia — unstable pre-excited tachyarrhythmia requiring immediate synchronised DCCV
    haemodynamic_instability_with_wide_irregular_tachycardia
  • history
    Known accessory pathway / prior AVRT, now presenting in atrial flutter — high arrhythmic risk; AV-nodal-blocker avoidance pathway
    prior_accessory_pathway_or_avrt_now_in_flutter
  • history
    Resuscitated cardiac arrest with pre-excitation on the post-ROSC ECG — pre-excited AF/flutter degenerating to VF as the arrest mechanism
    resuscitated_arrest_with_pre_excitation_on_post_rosc_ecg

Required inputs (10)

  • agerequired
    demographic • used at CONTEXT
    Younger patients with WPW + pre-excited AF/flutter are at particular SCD risk; age frames ablation urgency and occupational/sports clearance
  • sex
    demographic • used at CONTEXT
    Informs ablation planning and pregnancy considerations for antiarrhythmic selection
  • known_wpw_or_prior_delta_waverequired
    history • used at FRAME
    Prior documented pre-excitation greatly raises pretest probability and immediately invokes the AV-nodal-blocker contraindication
  • blood_pressurerequired
    vital • used at ENTRY
    Haemodynamic stability determines immediate synchronised DCCV vs a controlled pharmacologic strategy
  • heart_raterequired
    vital • used at ENTRY
    Very high ventricular rates and a short shortest-pre-excited R-R interval mark high VF risk
  • twelve_lead_ecgrequired
    imaging • used at INITIAL_WORKUP
    Defines the broad irregular pre-excited morphology, the shortest pre-excited RR (risk marker), and differentiates from VT/SVT-with-aberrancy
  • medications_given_prehospital_or_in_edrequired
    history • used at RED_FLAGS
    Inadvertent adenosine/AV-nodal blocker administration can precipitate VF and changes immediate management/monitoring
  • electrolytesrequired
    lab • used at INITIAL_WORKUP
    Potassium/magnesium correction supports rhythm stability and antiarrhythmic safety (QT for ibutilide)
  • troponin
    lab • used at BRANCHING_WORKUP
    Rate-related demand ischaemia or a degenerating arrhythmia may elevate troponin; informs disposition
  • structural_heart_disease_status
    history • used at CONTEXT
    Procainamide/ibutilide selection and ablation planning depend on structural heart disease and LV function

12-phase flow (11)

  1. 1FRAME
    Pre-excited atrial flutter = flutter/AF conducting antegrade down a non-decremental accessory pathway → potentially very rapid broad tachycardia that can degenerate to VF. The single most important rule: NO AV-nodal blockers (adenosine, IV diltiazem/verapamil, beta-blockers, digoxin, IV amiodarone)
    inputs: known_wpw_or_prior_delta_wave
    advance: pre-excited mechanism framed + AV-nodal-blocker contraindication flagged
  2. 2ENTRY
    Assess haemodynamic stability immediately. UNSTABLE (hypotension, shock, ischaemia, pulmonary oedema, depressed consciousness) → prepare immediate synchronised DC cardioversion. STABLE → controlled pharmacologic rhythm control with a pathway-prolonging agent
    inputs: blood_pressure, heart_rate
    advance: stability triaged + cardioversion readiness established
  3. 3CONTEXT
    Prior WPW/AVRT history, prior EP study/ablation, structural heart disease + LV function, athlete/high-risk occupation, pregnancy, current antiarrhythmics, family history of SCD
    inputs: age, structural_heart_disease_status
    advance: context complete
  4. 4RED_FLAGS
    Haemodynamic instability; degeneration to VF/polymorphic VT; inadvertent AV-nodal blocker already given (heightened VF watch + pads on); shortest pre-excited RR <250 ms; syncope/arrest as the presentation (highest-risk pathway)
    inputs: medications_given_prehospital_or_in_ed
    actions: wide_complex_tach
    advance: life-threatening features + drug-safety screen complete
  5. 5INITIAL_WORKUP
    12-lead ECG (broad irregular pre-excited morphology; measure shortest pre-excited RR), continuous telemetry, defibrillator pads applied, IV access, electrolytes (K/Mg), bedside echo if structural concern; CXR if pulmonary oedema
    inputs: twelve_lead_ecg, electrolytes
    actions: panel.cardiac
    advance: rhythm characterised + resuscitation readiness in place
  6. 6BRANCHING_WORKUP
    Differentiate pre-excited AF/flutter from polymorphic VT and SVT-with-aberrancy; troponin if ischaemic features; assess for precipitants (thyroid, sympathomimetics, alcohol); plan electrophysiology study for pathway risk stratification + ablation
    inputs: troponin
    actions: panel.coag
    advance: diagnosis confirmed + precipitants assessed + EP referral framed
  7. 7RISK_STRATIFICATION
    Shortest pre-excited RR in AF <250 ms, multiple accessory pathways, syncope/arrest presentation, inducible AF/AVRT at EP study = high-risk pathway warranting expedited ablation. MAP/instability drives acute pathway (DCCV vs drug)
    inputs: blood_pressure
    actions: calc.map
    advance: arrhythmic risk + acute strategy decided
  8. 8TREATMENT
    UNSTABLE → immediate SYNCHRONISED DC cardioversion (start 100-200 J biphasic; escalate). STABLE → IV procainamide (first-line; prolongs accessory-pathway refractoriness) or IV ibutilide; proceed to DCCV if drug fails or instability develops. ABSOLUTELY AVOID adenosine, IV diltiazem/verapamil, beta-blockers, digoxin, IV amiodarone (may accelerate pathway conduction → VF). Correct K/Mg. Definitive: accessory-pathway catheter ablation (Class I after pre-excited AF/flutter)
    inputs: blood_pressure, medications_given_prehospital_or_in_ed
    advance: sinus rhythm restored safely + ablation referral made
  9. 9DISPOSITION
    Admit to a monitored bed/telemetry after a pre-excited AF/flutter episode; expedited electrophysiology consult for ablation. ICU if instability, arrest, or post-cardioversion monitoring required
    advance: monitored disposition + EP pathway documented
  10. 10MONITORING
    Continuous telemetry for recurrence/VF; post-cardioversion rhythm and neuro checks; QT monitoring if ibutilide used (torsades risk, watch ≥4 h); electrolyte normalisation; readiness for repeat DCCV
    actions: panel.cardiac
    advance: stable monitored period without recurrence
  11. 11FOLLOWUP
    Electrophysiology: accessory-pathway ablation (curative; Class I post pre-excited AF/flutter) — confirm bidirectional pathway block; sports/occupational clearance only after successful ablation or reassuring risk stratification; family screening if SCD history; document lifelong AV-nodal-blocker avoidance until pathway eliminated; anticoagulation per CHA2DS2-VASc if AF component persists
    advance: ablation completed/scheduled + clearance + avoidance documentation in place