Related Experiment Videos
Electrocardiographic criteria of left ventricular hypertrophy in left bundle-branch block
Insights
The Sokolow criteria for left ventricular hypertrophy are applicable even with left bundle-branch block, though specificity is limited. QRS axis measurements are not helpful in this context.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Left ventricular hypertrophy (LVH) is a common cardiac condition.
- Left bundle-branch block (LBBB) can alter electrocardiogram (ECG) findings.
- Assessing LVH in the presence of LBBB is diagnostically challenging.
Purpose of the Study:
- To evaluate the validity of standard electrocardiographic criteria for LVH in patients with LBBB.
- To determine if the Sokolow index remains reliable for diagnosing LVH during LBBB episodes.
Main Methods:
- Studied 79 patients with intermittent left bundle-branch block.
- Compared QRS voltage and axis before and after LBBB onset.
- Excluded cases of incomplete LBBB.
Main Results:
- Significant correlations were found between pre- and post-LBBB QRS voltage and axis.
- R wave voltage decreased, S wave voltage increased, and QRS axis shifted leftward with LBBB onset.
- The Sokolow index for LVH remained unchanged despite LBBB.
Conclusions:
- The Sokolow criteria can be satisfactorily applied to diagnose LVH in the presence of LBBB.
- Specificity of the Sokolow criteria for LVH is reduced in LBBB.
- QRS axis is not a useful indicator for LVH when LBBB is present.
Abstract:
In order to determine whether the electrocardiographic criteria of left ventricular hypertrophy apply in the presence of left bundle-branch block we studied 79 cases of intermittent left bundle-branch block and compared the QRS voltage and axis before and after its onset. Cases of incomplete left bundle-branch block were excluded. There was a statistically significant correlation between pre- and post-left bundle-branch block values of R or S wave voltage in leads I, V1, V2, V5, and V6, the Sokolow index (R V5 or V6 + S V1), and the QRS axis. There was a statistically significant reduction in R wave voltage in leads I, V5, and V6, an increase in S wave voltage in V1 and V2, and leftward shift of QRS axis, but the Sokolow index remained unchanged, after the onset of left bundle-branch block. The Sokolow criteria for left ventricular hypertrophy apply satisfactorily even in the presence of left bundle-branch block, though specificity is low, but QRS axis is unhelpful.