[The vectorcardiogram in A-V canal in the first three years of life: qualitative and quantitative analysis (author's transl)].

The electrocardiograms and the vectocardiograms of 26 childrens, up to 3 years of age, affected by A-V canal, were been analyzed. The pattern of QRS loop in the 3 planes, the voltage of right maximum spatial vector (RMSV) and left maximum spatial vector (LMSV), their projection onto the horizontal (azimuth) and frontal plane (elevation) were related to right ventricular systolic pressure. The qualitative and quantitative evaluation of VCG Showed a better correlation with the haemodynamic data than the electrocardiogram. In all but 3 cases, the high frequency of superior orientation and counterclockwise rotation of QRS loop in the frontal plane was found; moreover the good correlation of right ventricular systolic pressure to the rotation of QRS loop on the horizontal plane was also confirmed. In fact, the latter was counterclockwise in the cases with a low pressure, whereas it became clockwise in those with higher pressure. Moreover a good direct correlation of the right ventricular pressure with forward orientation of LMSV on the horizontal plane was found. In differential diagnoses with other congenital heart diseases with superior orientation and anticlockwise rotation on the frontal plane, useful results were obtained by using the calculation of elevation time (the interval between point 0 and intersection of the QRS loop with the axis) which is significantly lower in the A-V canal. Terminal forces directed posteriorly and to the right and with a delay no longer than 0,03 inches do not warrant the diagnosis of left anterior hemiblock with a right bundle branch block associated. On the contrary, on the basis of anatomical and electrophysiologic studies we believe that in this disease there is an asinchrony in the activation i.e. the postero-inferior region, then the left lateral wall and finally the tree high part of right ventricle wall are sequentially activated.