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cardio.cardiogenic-shock.lyme-carditis.v1

Cardiogenic shock / high-grade AV block — Lyme carditis

cardiologyacuteadultacuteinpatienttransitionoutpatient
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Phase E variant of cardio.cardiogenic-shock.core.v1 — narrowed to Lyme carditis with high-grade AV block ± cardiogenic shock per IDSA / AAN / ACR Lyme Disease Clinical Practice Guidelines 2021 (Lantos PMID 33417672) + CDC Lyme Disease Clinician Guidance + Modified Two-Tier Testing 2019. Pathophysiology: Borrelia burgdorferi spirochete invades myocardium / conduction system causing carditis in 1-10% of untreated Lyme cases; classic phenotype is HIGH-GRADE AV BLOCK (Mobitz II, CHB) that fluctuates hour-to-hour and resolves within days-weeks with antibiotics; less commonly myopericarditis with LV dysfunction; rare fulminant myocarditis with overt shock. Demographics: endemic regions (Northeast US, upper Midwest, Pacific Northwest); summer / early fall presentation; previously healthy young / middle-aged adults; tick (Ixodes scapularis / pacificus) exposure history; 50-70% recall a bite or erythema migrans rash but absence does NOT rule out diagnosis. Diagnosis: ECG (fluctuating-degree AV block — pathognomonic when seen in young/middle-aged patient from endemic region), bedside echo (LV / RV / pericardial / valvular), two-tier serology (ELISA → Western blot OR modified two-tier per CDC 2019), blood cultures × 3 (rule out IE), CSF analysis if neuro symptoms (concurrent Lyme meningitis), cardiac MRI optional. Treatment ACUTE: CEFTRIAXONE 2 g IV q24h × 14-21 d for high-grade AV block / hospitalized carditis (28 days if neuroborreliosis); doxycycline 100 mg PO BID × 14-21 d for mild conduction outpatient; doxycycline IV alternative if severe penicillin allergy; TEMPORARY transvenous pacing if symptomatic CHB; AVOID permanent pacer in acute window (conduction recovers in 90%+ per IDSA 2021); standard CS support if hemodynamic compromise from rare fulminant variant. Long-term: complete recovery in 90%+ with timely antibiotics; tick-bite prevention counseling (repellent, tick checks, prompt removal); single-dose doxycycline 200 mg post-exposure prophylaxis for future Ixodes attachments ≥36 h per IDSA 2021; permanent pacer evaluation ONLY if conduction does not recover by 6 weeks (rare). Inherits parent CS framework (vasopressor / inotrope ladder, MCS escalation, MDT activation); specialises for Lyme carditis — antibiotic-cure of underlying infection, temporary-only pacing, excellent recovery prognosis, tick-bite prevention focus, ID stewardship for concurrent Lyme features. Status INTEGRATED until terminology + RxNav-validated drug codes are reconciled. Authored 2026-05-15 by shard-06-cardio-acute as Phase E wave 20 infection-driven cardiac variant.

Entry points (5)

  • imaging
    New high-grade AV block (Mobitz II / CHB) in patient from endemic region with tick exposure or erythema migrans → Lyme carditis until proven otherwise
    ecg_high_grade_av_block_with_lyme_exposure
  • symptom
    Fluctuating-degree AV block (1st-degree → Mobitz I → CHB hour-to-hour) in previously healthy young/middle-aged adult — pathognomonic for Lyme carditis
    fluctuating_av_block_in_young_healthy_adult
  • history
    Recent erythema migrans rash + new palpitations / syncope / dyspnea → Lyme carditis evaluation with ECG + echo + serology
    recent_erythema_migrans_with_palpitations_or_syncope
  • symptom
    Fulminant Lyme myocarditis presentation with new severe LV dysfunction + shock physiology in patient from endemic area
    fulminant_lyme_myocarditis_with_cardiogenic_shock
  • history
    Tick exposure in endemic region during summer/early fall + new conduction abnormality or LV dysfunction
    tick_exposure_endemic_region_summer_with_carditis

Required inputs (17)

  • agerequired
    demographic • used at CONTEXT
    Most cases in 20-50 year-olds; older patients may have higher baseline AV node dysfunction confounding diagnosis
  • sbprequired
    vital • used at RED_FLAGS
    SCAI 2022 staging baseline; symptomatic bradycardia + SBP <90 = pacing + vasopressor indication
  • hrrequired
    vital • used at RED_FLAGS
    CHB with escape rate <40 = high-risk; defines symptomatic bradycardia threshold for temporary pacing
  • spo2required
    vital • used at INITIAL_WORKUP
    Pulm congestion if myocarditis-driven LV dysfunction; intubation rarely needed
  • troponinrequired
    lab • used at INITIAL_WORKUP
    Mildly-to-moderately elevated in Lyme carditis; helps gauge myocardial involvement vs pure conduction system disease
  • bnp_ntprobnprequired
    lab • used at INITIAL_WORKUP
    Elevated if LV dysfunction component; trends recovery on antibiotics
  • lyme_serologyrequired
    lab • used at INITIAL_WORKUP
    Two-tier ELISA → Western blot (IgM early, IgG established); modified two-tier per CDC 2019 update; obtain at admission and at 4-6 weeks if initial negative + clinical suspicion high
  • creatininerequired
    lab • used at CONTEXT
    Baseline renal function for ceftriaxone (no dose adjust) vs other agents; cardio-renal monitoring
  • blood_culturesrequired
    lab • used at INITIAL_WORKUP
    Modified Duke criteria exclusion — rule out infective endocarditis as alternative cause of AV block (aortic root abscess) and shock
  • ecgrequired
    imaging • used at INITIAL_WORKUP
    Diagnostic anchor — fluctuating-degree AV block (1st-degree → Mobitz II → CHB); document conduction status hour-to-hour during acute phase
  • echorequired
    imaging • used at INITIAL_WORKUP
    LV function, RV strain, pericardial effusion, valvular function (rule out IE), wall motion abnormalities
  • cxrrequired
    imaging • used at INITIAL_WORKUP
    Pulmonary congestion if myocarditis-driven LV dysfunction; cardiac silhouette typically normal
  • cardiac_mri
    imaging • used at BRANCHING_WORKUP
    Late gadolinium enhancement pattern of myocarditis if diagnosis uncertain or for prognostication; not required for treatment initiation
  • tick_exposurerequired
    history • used at CONTEXT
    Endemic region + outdoor exposure + warm-season timing supports diagnosis; only 50-70% recall bite or rash
  • erythema_migrans_history
    history • used at CONTEXT
    Pathognomonic if bull's-eye rash present in past weeks-months; absence does not rule out diagnosis
  • penicillin_allergyrequired
    history • used at CONTEXT
    Drives antibiotic selection — ceftriaxone vs IV doxycycline alternative if anaphylaxis-class beta-lactam allergy
  • neuro_symptoms
    history • used at CONTEXT
    Headache / cranial nerve palsy / radiculopathy → CSF analysis for concurrent Lyme meningitis (changes antibiotic duration to 2-4 weeks IV)

12-phase flow (11)

  1. 1FRAME
    Confirm Lyme carditis as the etiology of conduction collapse / pump failure — endemic region + tick exposure + fluctuating-degree AV block in young/middle-aged previously healthy adult; identify whether presentation is conduction-only (most common) vs combined conduction + myocarditis with shock (rare but recoverable)
    inputs: ecg, tick_exposure
    advance: Lyme carditis confirmed as working diagnosis with sub-phenotype (conduction vs myocarditis-shock) stated
  2. 2ENTRY
    Continuous ECG monitoring + IV access + transcutaneous pacer pads ready; activate cards/EP team if CHB; mobilize ID team for antibiotic stewardship; bedside echo for LV/RV function; STAT serology + blood cultures (rule out IE)
    inputs: hr, sbp
    advance: Monitoring + IV access + pacer pads + cards/EP/ID consults active
  3. 3CONTEXT
    Endemic exposure history (region, season, outdoor activities), erythema migrans history, neuro symptoms (concurrent meningitis), penicillin allergy (drives drug selection), comorbidities, baseline ECG if available
    inputs: age, tick_exposure, erythema_migrans_history, penicillin_allergy, neuro_symptoms, creatinine
    advance: Context complete and antibiotic plan drafted (ceftriaxone IV vs doxycycline PO/IV per severity + allergy)
  4. 4RED_FLAGS
    Symptomatic CHB / hemodynamically unstable bradycardia → temporary transvenous pacing; refractory shock from fulminant myocarditis → MCS escalation; concurrent neuro symptoms → CSF analysis
    inputs: hr, sbp
    actions: cardiogenic_shock
    advance: Pacing decision made and emergent intervention triggered if needed
  5. 5INITIAL_WORKUP
    ECG (q4-6h serial during acute phase given fluctuating block), bedside echo, troponin, BNP/NT-proBNP, BMP, CBC, coags, two-tier Lyme serology (ELISA → Western blot), blood cultures × 3 (rule out IE), CXR
    inputs: ecg, echo, troponin, bnp_ntprobnp, lyme_serology, blood_cultures, cxr
    actions: panel.cardiac, panel.renal, panel.coag
    advance: Workup complete and Lyme carditis confirmed serologically (or empiric treatment started while awaiting if high pre-test probability)
  6. 6BRANCHING_WORKUP
    Cardiac MRI if myocarditis pattern needed for prognosis or DDx; CSF analysis if neuro symptoms (concurrent Lyme meningitis); TEE if endocarditis suspicion persists; right-heart cath rarely needed
    inputs: cardiac_mri
    advance: Branching diagnostics complete or deferred based on clinical trajectory
  7. 7RISK_STRATIFICATION
    SCAI 2022 staging if shock physiology; conduction-system risk stratification (PR interval, escape rate, fluctuation pattern); concurrent neuro / arthritis findings (disseminated Lyme); penicillin allergy severity; surgical risk if pacer needed
    inputs: sbp, hr, troponin
    advance: Risk stratified and conduction-recovery vs persistent-block likelihood estimated
  8. 8TREATMENT
    CEFTRIAXONE 2 g IV q24h × 14-21 d for high-grade AV block / hospitalized carditis (IDSA 2021 PMID 33417672); doxycycline 100 mg PO BID × 14-21 d for mild conduction outpatient; doxycycline IV alternative if penicillin allergy; TEMPORARY transvenous pacing if symptomatic CHB; standard CS support if hemodynamic compromise; AVOID permanent pacer in acute window (conduction recovers in 90%+)
    inputs: hr, sbp, creatinine
    advance: Antibiotics started + pacing decision documented + CS support active if indicated
  9. 9DISPOSITION
    CICU / step-down with continuous telemetry while high-grade AV block present; transition to floor when block resolves to 1st-degree or normal; discharge planning includes IV antibiotic completion (PICC line for outpatient ceftriaxone) or PO doxycycline transition
    advance: Disposition assigned with telemetry + antibiotic completion plan documented
  10. 10MONITORING
    Continuous telemetry until conduction normalizes; daily ECG documentation; daily troponin + BNP trend; LFT + CBC weekly during ceftriaxone; serial echo at 48-72 h to confirm LV recovery if myocarditis component
    inputs: ecg, echo, troponin
    actions: panel.cardiac, panel.renal
    advance: Monitoring cadence set + recovery trajectory documented
  11. 11FOLLOWUP
    Repeat ECG + echo at 1 month + 3 months post-completion; cardiology / EP follow-up if persistent conduction abnormality at 6 weeks (pacer evaluation); ID follow-up for concurrent Lyme features (arthritis, neuro); tick-bite prevention counseling; consider single-dose doxycycline 200 mg post-exposure prophylaxis future Ixodes attachments ≥36 h per IDSA 2021
    advance: Follow-up booked + recovery confirmation echo / ECG scheduled + prevention counseling completed