Two cases of accessory pathways located at the aortomitral continuity: clues from the 12-lead ECG where the algorithms have failed.

摘要

Several algorithms have been proposed to help determine the location of an accessory pathway from the preexcited 12-lead ECG. This can be useful in planning ablation strategy as well as informing the patient of potential risks of the procedure, which depend in part on the likely site of the accessory pathway. Some of these algorithms are based on the polarity of the QRS complex,1'2 whereas others are based on a combination of QRS and delta wave polarities. However, none of these algorithms is 100% sensitive or specific. For example, the algorithm devised by Arruda et al had an overall sensitivity of 90% and specificity of 99% among the 121 patients against whom the algorithm was prospectively tested. Furthermore, considerable variation between algorithms can exist in the predicted site of the accessory pathway, particularly in cases with minimal preexcitation or preexcitation in more unusual locations.6 Here we report two cases in which the algorithms failed to predict the site of the accessory pathway. In both cases, the successful ablation site was in the region of the aortomitral continuity, a site at which accessory pathways are not thought to exist. We describe the ECG characteristics of the two patients and discuss how the pattern of preexcitation can be used by others in predicting this unusual accessory pathway location.