Phase image characterization of ventricular contraction in left anterior hemiblock
Related Experiment Videos
1Second Department of Internal Medicine, Kyorin University School of Medicine, Tokyo, Japan.
Insights
Left anterior hemiblock may coexist with right bundle branch block in patients with both conditions. However, left anterior hemiblock is unlikely in most patients with isolated left axis deviation.
Area of Science:
- Cardiology
- Medical Imaging
- Electrophysiology
Background:
- Left axis deviation (LAD) can be associated with various cardiac conditions.
- Distinguishing between isolated LAD and coexisting conduction abnormalities is clinically important.
- First-harmonic Fourier analysis of gated blood-pool images offers quantitative insights into cardiac electrical activity.
Purpose of the Study:
- To investigate the presence of left anterior hemiblock (LAH) in patients with left axis deviation (LAD).
- To differentiate between isolated LAD and combined right bundle branch block (RBBB) with LAD using cardiac imaging analysis.
Main Methods:
- Utilized first-harmonic Fourier analysis on ECG-gated blood-pool images from 50 patients.
- Included normal subjects, RBBB, LAD, and combined RBBB + LAD groups.
- Quantified regional phase shift (RPS) by comparing global left ventricular phase angles with high lateral region phase angles.
Main Results:
- Left ventricular phase changes and RPS were similar between normal, RBBB, and LAD groups.
- The RBBB + LAD group exhibited delayed phase changes in the high anterolateral region.
- RPS values were significantly lower (p < 0.01) in the RBBB + LAD group compared to others.
Conclusions:
- Data suggest that left anterior hemiblock may coexist with right bundle branch block in patients presenting with RBBB + LAD.
- Left anterior hemiblock is likely absent in the majority of patients with isolated left axis deviation.
- First-harmonic Fourier analysis of gated blood-pool imaging can help differentiate complex conduction abnormalities.
Abstract:
We investigated whether or not left anterior hemiblock is present in patients with left axis deviation using first-harmonic Fourier analysis of gated blood-pool images. Gated blood-pool images were taken in 50 patients without contraction abnormality. They included 14 normal subjects, 8 patients with right bundle branch block (RBBB), 20 with left axis deviation (LAD) and 8 with both RBBB and LAD (RBBB + LAD). ECG gated blood-pool scans were acquired in the anterior and "best septal" left anterior oblique projections. First, the phase images were displayed cinematically as a continuous-loop movie. Next, for quantitative analysis of the phase image, the whole left ventricular and left ventricular high lateral regions of interest were drawn. The "regional phase shift" (RPS) was then defined as (RPS = A-a) where "A" is the mean value of the whole left ventricular phase angles and "a" is that of phase angles in the high lateral region. The left ventricular phase changes and the RPSs in the RBBB and LAD groups were similar to those in the normal group. In the RBBB + LAD group, the latest phase changes occurred in the high anterolateral region. The RPSs of this group were significantly lower than those in the other 3 groups (p less than 0.01). These data suggest that left anterior hemiblock might coexist with RBBB in patients with RBBB + LAD, whereas left anterior hemiblock might not exist in the majority of patients with LAD alone.