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cardio.atrial_flutter.atrial-septal-defect-related.v1

Atrial flutter in adult unrepaired/late-repaired atrial septal defect (RA volume overload → CTI macroreentry)

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Phase E structural-substrate variant of cardio.atrial_flutter.v1 — atrial flutter in adult unrepaired or late-repaired secundum ASD. Population: adults with secundum ASD; 10-15% develop AFL/AF by 40 yr, 25-50% by 60 yr (Berger 1999 PMID 10468420). Substrate: chronic L→R shunt → RA + RV volume overload → RA enlargement + stretch → CTI macroreentry (right-sided typical AFL dominant). Treatment paradigm: standard AC + acute rate/rhythm + CTI ablation Class I (>95% acute success per Calkins 2007 PMID 17572388) + CONCURRENT ASD DEVICE CLOSURE if hemodynamically significant (Qp/Qs ≥1.5, RV dilation, PASP <50% systemic) per AHA/ACC 2018 ACHD (Stout PMID 30121239). Combined-session percutaneous device closure (Amplatzer Septal Occluder / Gore Cardioform) + CTI ablation now standard of care at high-volume ACHD-EP centres. Critical decision points: (1) Eisenmenger physiology (PASP >2/3 systemic, fixed PHT, R→L shunt) CONTRAINDICATES closure (Class III); (2) paradoxical embolism (cryptogenic stroke / TIA) upgrades closure urgency; (3) lifelong AC even after closure if RA remains enlarged given substrate persistence (Silversides 2004 PMID 15036666); (4) mixed AF/AFL coexistence common — combined PVI + CTI + closure may be needed at single session. Sister engines: cardio.atrial_flutter.adult-congenital-heart-disease.v1 (broader CHD with surgical scar substrate vs ASD-specific structural substrate), cardio.atrial_flutter.typical-cavotricuspid.v1 (same CTI circuit but no congenital substrate or closure decision), cardio.atrial_flutter.v1 (parent). Mixed AF/AFL → cross-link to cardio.afib.core.v1. Manifest pointer reuses cardio.atrial_flutter.v1 manifest. Design-brief pointer reuses parent. Status INTEGRATED. Authored 2026-05-15 by shard-06-cardio-acute.

Entry points (6)

  • history
    New atrial flutter / palpitations in adult with known unrepaired or late-repaired secundum ASD — RA volume-overload substrate + CTI macroreentry
    new_atrial_flutter_in_adult_with_known_asd
  • imaging
    Atrial flutter on ECG with RV volume-overload pattern (RBBB or rSR' V1, right axis, RA enlargement) — undiagnosed ASD or known ASD presenting with arrhythmia
    flutter_ecg_with_rv_volume_overload_pattern
  • symptom
    Palpitations, dyspnea on exertion, or reduced exercise tolerance in adult with systolic flow murmur + fixed split S2 → undiagnosed ASD + new AFL
    palpitations_dyspnea_in_adult_with_systolic_murmur_fixed_split_s2
  • imaging
    TTE shows secundum ASD with RA + RV dilation + L→R shunt + atrial flutter on telemetry — combined structural + arrhythmia substrate confirmed
    tte_with_asd_+_ra_enlargement_+_aflutter
  • history
    Recurrent atrial flutter after late-life ASD closure (>40 yr at closure) — substrate persistence post-closure given irreversible RA remodelling (Silversides 2004 PMID 15036666)
    recurrent_aflutter_after_late_asd_closure
  • vital_abnormality
    Unexplained paradoxical embolism (cryptogenic stroke / TIA) + new AFL → patent intracardiac shunt (ASD or PFO) workup; AFL drives R→L shunt thrombus passage
    unexplained_paradoxical_embolism_with_aflutter

Required inputs (12)

  • agerequired
    demographic • used at CONTEXT
    Adult ASD AFL prevalence rises with age — 10-15% by 40, 25-50% by 60 (Berger 1999 PMID 10468420); CHA2DS2-VASc + ablation candidacy + life expectancy
  • sbprequired
    vital • used at RED_FLAGS
    SBP <90 with AFL RVR + ASD physiology → emergent DCCV 50-100 J biphasic; ASD shunt may worsen hemodynamic compromise
  • hrrequired
    vital • used at CONTEXT
    Conduction ratio variable — ASD-AFL often 2:1 (HR ~150) with right-sided typical CTI circuit; rate control target 80-110
  • ecg_12_leadrequired
    imaging • used at INITIAL_WORKUP
    Sawtooth flutter waves negative in II/III/aVF + positive in V1 (counterclockwise CTI-typical); RBBB or rSR' V1 + right axis + RA enlargement = ASD signature — Saoudi 2001 (PMID 11428013)
  • asd_diagnosis_+_size_+_shunt_severityrequired
    history • used at CONTEXT
    Anchors substrate; ASD type (secundum >> primum/sinus venosus), defect size, Qp/Qs ratio, RV dilation severity, PASP — drives concurrent closure decision per AHA/ACC 2018 ACHD (PMID 30121239)
  • creatinine_egfrrequired
    lab • used at INITIAL_WORKUP
    DOAC dosing + contrast for ASD device closure + AAD dosing
  • tshrequired
    lab • used at INITIAL_WORKUP
    Reversible cause screen — thyrotoxic flutter overlay common in adult ASD
  • tte_with_bubble_studyrequired
    imaging • used at INITIAL_WORKUP
    TTE with agitated saline bubble study — confirms shunt; LA + RA size, RV size + function, PASP, valvular function (mitral cleft if primum ASD), Qp/Qs estimation
  • tee_pre_closure_+_ablation
    imaging • used at BRANCHING_WORKUP
    Defines ASD anatomy (rim adequacy for device closure), excludes LAA thrombus pre-CV, identifies sinus venosus or partial anomalous pulmonary venous connection (PAPVC) frequently coexists
  • cha2ds2_vasc_factorsrequired
    history • used at RISK_STRATIFICATION
    AC indication identical to AF; LIFELONG typical given persistent RA substrate even after closure — Khairy 2010 GUCH-AF (PMID 20660806)
  • bleeding_historyrequired
    history • used at RISK_STRATIFICATION
    HAS-BLED + peri-procedure bleed risk for combined closure + ablation
  • paradoxical_embolism_history
    history • used at CONTEXT
    Cryptogenic stroke / systemic embolism history → R→L shunt evidence; AC strategy + closure urgency upgraded

12-phase flow (11)

  1. 1FRAME
    Structural ASD-substrate AFL — typical CTI macroreentry from chronic RA volume overload (L→R shunt). Adult ASD prevalence of AFL: 10-15% by 40 yr / 25-50% by 60 yr (Berger 1999 PMID 10468420). Combined CTI ablation + concurrent ASD closure now standard if hemodynamically significant shunt — AHA/ACC 2018 ACHD (PMID 30121239)
    inputs: ecg_12_lead, asd_diagnosis_+_size_+_shunt_severity
    advance: ASD substrate + AFL morphology confirmed
  2. 2ENTRY
    New palpitations / dyspnea / fatigue / reduced exercise tolerance / cryptogenic stroke / incidental ECG in adult with known or suspected ASD; ED, cardiology clinic, ACHD clinic, or stroke service
    inputs: age
    advance: Engine entered
  3. 3CONTEXT
    ASD type (secundum >> primum / sinus venosus), defect size, Qp/Qs ratio, RV size + function, PASP, prior closure attempts, structural HD, pulmonary HTN status (Eisenmenger contraindicates closure), paradoxical embolism history, lifestyle modifiables (alcohol, weight, OSA — recurrence drivers)
    inputs: hr, cha2ds2_vasc_factors, bleeding_history, asd_diagnosis_+_size_+_shunt_severity
    advance: Context complete
  4. 4RED_FLAGS
    Hemodynamic instability (SBP <90, pulmonary edema, ischemia, AMS) → synchronized DCCV 50-100 J biphasic now (typical flutter cardioverts at lower energy than AF); Eisenmenger-equivalent fixed pulmonary HTN (PASP >2/3 systemic, R→L shunt) → AVOID closure (closure precipitates RV failure); paradoxical embolism with stroke → urgent neurology + AC
    inputs: sbp
    actions: tachycardia
    advance: Stable or cardioverted + Eisenmenger excluded
  5. 5INITIAL_WORKUP
    ECG, TSH, BMP/Mg, creatinine, CBC, BNP, TTE with bubble study — baseline + structural anatomy + shunt direction + RA/RV/PASP
    inputs: ecg_12_lead, tsh, creatinine_egfr, tte_with_bubble_study
    actions: panel.cardiac, panel.renal
    advance: Stage-1 returned
  6. 6BRANCHING_WORKUP
    TEE for ASD anatomy (rim adequacy for device closure) + LAA thrombus exclusion; right heart cath if PASP >50% systemic on TTE (need to confirm operability — fixed vs reversible pulm HTN); cardiac MRI for Qp/Qs quantification + RV volume; concomitant AF surveillance via Holter (mixed AF/AFL frequent in adult ASD)
    inputs: tee_pre_closure_+_ablation
    actions: acs_pathway, afib_new_onset
    advance: Branch resolved + closure candidacy decided
  7. 7RISK_STRATIFICATION
    CHA2DS2-VASc (AC indication identical to AF — Class I per ACC/AHA 2024 PMID 38753446) + HAS-BLED + eGFR for DOAC + AAD dose + ablation candidacy; lifelong AC typical given persistent RA substrate (Khairy 2010 GUCH-AF PMID 20660806)
    inputs: cha2ds2_vasc_factors, bleeding_history
    advance: Risk tier documented
  8. 8TREATMENT
    Acute: rate control (BB or non-DHP CCB if EF preserved; AVOID non-DHP CCB if RV dysfunction or pulm HTN). Definitive: CTI ablation Class I (>95% acute success per Calkins 2007 PMID 17572388) + CONCURRENT ASD CLOSURE in same EP procedure if Qp/Qs ≥1.5 + RV dilation + PASP <50% systemic per AHA/ACC 2018 ACHD (PMID 30121239). AC continuous through procedure; mixed AF/AFL coexistence common — ACC/AHA 2024 (PMID 38753446)
    inputs: hr, creatinine_egfr
    advance: Acute strategy + AC + EP combined-procedure referral booked
  9. 9DISPOSITION
    Admit if unstable, AAD initiation requiring monitoring (dofetilide REMS), recent combined closure + ablation observation, or post-CV; discharge if rate-controlled with AC and EP combined-procedure booked
    advance: Disposition documented
  10. 10MONITORING
    Telemetry; QTc on dofetilide / sotalol / amiodarone; post-combined-procedure observation for groin hematoma, tamponade, device embolization (rare ~0.5%), atrioesophageal fistula (lower risk for right-sided CTI vs LA lines); AC adherence
    inputs: ecg_12_lead
    advance: Monitoring orders documented
  11. 11FOLLOWUP
    ACHD clinic + EP at 4 weeks post-procedure with 12-lead + Holter; AC continuation lifelong if persistent RA enlargement (substrate persistence — Silversides 2004 PMID 15036666); device endothelialization period 6 months — DAPT 1-6 mo per device + ASA lifetime; lifestyle (alcohol, weight, OSA per LEGACY); 3, 6, 12-month Holter; transition pediatric ACHD → adult ACHD if not yet established
    advance: Follow-up booked + ACHD pathway entered