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Results of the computer simulation: Typical LBBB patterns observed after slowing the conduction velocity in left ventricular myocardium without blocking the onset of left ventricular activation, i.e. without simulating the block in the left bundle branch. 12-lead ECG (a), vectorcardiogram (b), (H) horizontal plane, LS: left sagittal plane, (F) frontal plane. Adapted from: Bacharova L, Szathmary V, Mateasik A. Electrocardiographic patterns of left bundle-branch block caused by intraventricular conduction impairment in working myocardium: a model study. J Electrocardiol. 2011; 44 : 768–78. With permission.
Source publication
Intraventricular conduction disturbances (IVCD) are currently generally accepted as ECG diagnostic categories. They are characterized by defined QRS complex patterns that reflect the abnormalities in the intraventricular sequence of activation that can be caused by pathology in the His-Purkinje conduction system (HP) or ventricular myocardium. Howe...
Similar publications
Biventricular pacing (Biv) and left bundle branch area pacing (LBBAP) are methods of cardiac resynchronization therapy (CRT). Currently, little is known about how they differ in terms of ventricular activation. This study compared ventricular activation patterns in left bundle branch block (LBBB) heart failure patients using an ultra-high-frequency...
Citations
... Even assuming fixed intramyocardial conduction velocity, the larger the size of the LV, the longer it would take to activate it. Additionally, adverse remodeling results in impaired intraventricular conduction withing the working myocardium prolonging QRS duration, a mechanism applicable on top of presence of LBBB but also seen as non-specific intraventricular conduction delay when left bundle branch conduction is intact [34,35]. On the other hand, LV dilation may not have a consistent effect on QRS voltage. ...
Background:
Standard ECG criteria for left ventricular (LV) hypertrophy rely on QRS amplitudes. However, in the setting of left bundle branch block (LBBB), ECG correlates of LV hypertrophy are not well established. We sought to evaluate quantitative ECG predictors of LV hypertrophy in the presence of LBBB.
Methods:
We included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010-2020. Orthogonal X, Y, Z leads were reconstructed from digital 12‑lead ECGs using Kors's matrix. In addition to QRS duration, we evaluated QRS amplitudes and voltage-time-integrals (VTIs) from all 12 leads, X, Y, Z leads and 3D (root-mean-squared) ECG. We used age, sex and BSA-adjusted linear regressions to predict echocardiographic LV calculations (mass, end-diastolic and end-systolic volumes, ejection fraction) from ECG, and separately generated ROC curves for predicting echocardiographic abnormalities.
Results:
We included 413 patients (53% women, age 73 ± 12 years). All 4 echocardiographic LV calculations were most strongly correlated with QRS duration (all p < 0.00001). In women, QRS duration ≥ 150 ms had sensitivity/specificity 56.3%/64.4% for increased LV mass and 62.7%/67.8% for increased LV end-diastolic volume. In men, QRS duration ≥ 160 ms had a sensitivity/specificity 63.1%/72.1% for increased LV mass and 58.3%/74.5% for increased LV end-diastolic volume. QRS duration was best able to discriminate eccentric hypertrophy (area under ROC curve 0.701) and increased LV end-diastolic volume (0.681).
Conclusions:
In patients with LBBB, QRS duration (≥ 150 in women and ≥ 160 in men) is a superior predictor of LV remodeling esp. eccentric hypertrophy and dilation.
