A study on the transmural conduction velocity of activation front in the left ventricle of RBBB patients.

To investigate the effect of ventricular hypertrophy on the conduction velocity, the transmural conduction velocity was obtained from the findings of echocardiographic, and body surface potential mapping examinations on 20 RBBB patients. The transmural conduction velocity was linearly correlated with the ventricular septal thickness and the greater the thickness, the faster was the conduction velocity. There was no statistically significant difference in the duration of the left ventricular activation obtained from the mapping examinations as well as in the time of onset of intrinsicoid deflection in V5 between the group of left ventricular hypertrophy and that of non-hypertrophy. There was a good linear correlation between the imaginary distance covered by the activation front which proceeded in the direction from endocardium to epicardium during the left ventricular activation and the ventricular septal thickness. These findings were explicable from the faster conduction velocity in the hypertrophied ventricle. The increase in the conduction velocity in the hypertrophy group would be due to cable characteristics of hypertrophied cardiac cells and also due to increase in the number of multiple intercalated discs in the hypertrophied ventricle. It was concluded that the conduction velocity would be an important information to interpret the ECGs in ventricular hypertrophy as well as to estimate the pathological state of the heart.