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← Section V · Cardiac Masses, Pericardial Disease, Contrast and New Applications
V.E

Echocardiography in Disorders of Cardiac Rhythm and Conduction

8 cards

Notes

Atrial fibrillation

  • LA enlargement is both a cause and consequence.
  • Loss of A wave; no atrial contraction reflected on mitral inflow.
  • LAA emptying velocity < 20 cm/s → high thrombus risk.
  • Pre-cardioversion TEE recommended if AF > 48 hr without prior anticoagulation.
  • Spontaneous echo contrast (SEC) → marker of stasis and future embolic events.

Ventricular arrhythmias

  • Consider ARVC/D (RV enlargement, regional aneurysms, reduced FAC).
  • HCM (unexplained LVH, LGE on cMRI).
  • Cardiac sarcoidosis (patchy involvement, conduction disease, granulomas on PET/cMRI).
  • Anomalous coronary artery (SCD in young athletes).
  • Long QT / Brugada / catecholaminergic polymorphic VT (structurally normal heart).

Bundle branch blocks

  • LBBB - septal contraction delayed; paradoxical septal motion in preejection with subsequent normal thickening. Reduces global function estimates; may need to interpret EF/GLS with caution.
  • RBBB - Q wave in V1; often benign; may be seen post-cardiotomy.

Cardiac resynchronization therapy (CRT)

  • Criteria: LVEF ≤ 35 %, LBBB with QRS ≥ 150 ms, NYHA II-IV on OMT.
  • Echo assessment:
    • Baseline LV size and EF.
    • Interventricular mechanical delay (aortic PEP − pulmonary PEP > 40 ms suggests dyssynchrony).
    • Septal-to-posterior wall motion delay (SPWMD > 130 ms on M-mode).
    • CRT response: reduction in LV volumes ≥ 15 % on follow-up echo = 'reverse remodeling'.

Pacemaker- or ICD-lead complications

  • Pericardial effusion (perforation) → tamponade in worst case.
  • Tricuspid regurgitation from lead impingement.
  • Vegetation on lead (lead endocarditis).
  • RA thrombus on catheter.

Complete heart block

  • Sudden CHB after acute MI (inferior wall) - usually resolves; anterior MI CHB is more concerning (Purkinje damage).
  • CHB in an elderly patient with normal LV - consider cardiac sarcoidosis, cctga, Lyme carditis.

Ebstein's anomaly + WPW

  • ~25 % of Ebstein's patients have WPW (accessory pathway on tricuspid annulus). May present with SVT.

Rhythm and Doppler artifacts

  • Irregular rhythms produce beat-to-beat Doppler variability; average velocities over 3–5 beats (regular) or 5–10 beats (irregular).

Cards

  • basicV.E-001
    State the LAA emptying velocity threshold associated with high thrombus and embolic risk.
    → < 20 cm/s. Associated with severe spontaneous echo contrast, thrombus, and cardioembolic events. Normal LAA velocity ≥ 40 cm/s.
  • basicV.E-002
    When is a pre-cardioversion TEE recommended for atrial fibrillation?
    → AF duration > 48 hours (or unknown) without therapeutic anticoagulation for ≥ 3 weeks. TEE rules out LA/LAA thrombus, allowing cardioversion without prolonged anticoagulation.
  • basicV.E-003
    State the class I CRT indications from a functional perspective.
    → LVEF ≤ 35% with LBBB and QRS ≥ 150 ms; NYHA class II–III (ambulatory IV) on optimal guideline-directed medical therapy; sinus rhythm.
  • basicV.E-004
    What echocardiographic finding indicates a favorable response to cardiac resynchronization therapy on follow-up?
    → Reverse remodeling — a reduction in LV volumes ≥ 15% (typically LVESV reduction) with improvement in LVEF at 6 months post-implantation.
  • basicV.E-005
    How does LBBB affect septal motion on echo?
    → Septal contraction is delayed. The septum shows paradoxical anterior motion in pre-ejection followed by normal thickening. Global EF and strain estimates may need cautious interpretation.
  • basicV.E-006
    What is the septal-to-posterior wall motion delay (SPWMD) and what value suggests dyssynchrony?
    → Time interval on M-mode between maximal septal contraction and maximal posterior wall contraction. > 130 ms suggests significant intra-ventricular dyssynchrony (candidate marker for CRT response, though modern criteria rely on ECG and clinical parameters).
  • basicV.E-007
    Which congenital lesion is classically associated with WPW syndrome?
    → Ebstein's anomaly of the tricuspid valve (~25% have WPW; accessory pathway is on the tricuspid annulus).
  • basicV.E-008
    Which cardiomyopathy commonly presents with unexplained heart block in a young or middle-aged adult?
    → Cardiac sarcoidosis. Patchy myocardial involvement often produces AV block, VT, and (later) LV dysfunction. Diagnosis often requires PET or cMRI.