Studies on right ventricular outflow tract-wall abnormality and microelectric potential in idiopathic ventricular tachycardia and premature contraction originated from right ventricular outflow tract

Syncope and sudden death have been sporadically reported in the idiopathic premature contraction and tachycardia originated from the right ventricular outflow tract (RVOT), and MRI studies have shown the local wall abnormality in those cases. Authors studied the relationship between the RVOT-wall abnormality and microelectric potential and also in the sites of the local RVOT-wall abnormality and of successful ablation. MRI was performed in 11 cases of the ventricular tachycardia (VT), 11 of premature contraction (PVC) and 11 of the control without those symptoms using equipment Gyroscan 1.5T MASTER (Phlips Medical System). From the images, cases were divided in two groups of those with (+) wall abnormalities like thinning, hypertrophy, no contraction, knob and paradoxical knob, and without (-) abnormality to compare their summed mean electrocardiogram (ECG) parameters like root-mean square of the voltages in the last 40 ms (RMS40 inμV). Ablation was done in (+) cases of 8 VT and 3 PVC with catheters through the femoral vein. Dilated RVOT was found in VT and PVC. The (+) group was found to have less RMS40 than (-) group. Consistency of the abnormal site with successful ablation site was found in 6/7 cases out of 11 with RVOT-wall abnormality. It was suggested that the RVOT-wall abnormality can cause the VT more frequently than PVC and the abnormal site can be a measure of origin for arrhythmia. (T.I.)