QRS Polarity on 12-Lead Surface ECG

Abstract

In this study, we tried to disclose certain electrocardiogram (ECG) criteria that might be useful in the classification of posteroseptal accessory atrioventricular pathways as right and left in patients with pre-excitation in whom the accessory pathway localization was verified by subsequent successful ablation. Twenty such patients with posteroseptal accessory pathways (mean age 34.9 ± 9.8; 11 male, 9 female) were included in the study. Localization of the accessory pathway was right posteroseptal in 13 (65%) and left posteroseptal in 7 (35%). Common to all these 20 patients with posteroseptal accessory pathways was a QRS polarity positive in lead L1 and negative in leads D3, aVL. In patients with right posteroseptal accessory pathways, QRS polarity was negative in lead V1 in all and positive in lead V2 in 90%. On the other hand, none of the patients with left posteroseptal accessory pathways showed negative QRS polarity in lead V1.In conclusion, these findings strongly suggest that in patients with pre-excitation, a QRS polarity negative in lead V1 and positive in lead V2 is an important surface ECG finding that signifies right-sided localization of a posteroseptal accessory pathway. In cases with left posteroseptal accessory pathways, QRS polarity in leads V1 and V2 has been found to be either biphasic or positive.

Noninvasive Study of Ventricular Preexcitation Using Multichannel Magnetocardiography

“…Accurate preoperative localization and imaging of arrhythmogenic substrates can reduce the time required for invasive mapping and avoid unsuccessful interventions, especially when the clinical arrhythmia is not inducible during the procedure. For this reason, noninvasive localization of VPX has been attempted since the 1970s, 3–18 and in the early 1980s a first attempt was made to obtain accurate three‐dimensional localization of APs using body surface potential mapping and a mathematical inverse solution based on the single moving dipole model 6 . Because the inverse solution is simpler with magnetic data, MCG studies of WPW patients began in 1985 20,21 .…”

“…In clinical practice, 12‐lead electrocardiography (ECG), which remains the simplest noninvasive method of localizing APs, has gained better accuracy with algorithms based on the outcome of catheter ablation. Nevertheless, other methods, like body surface potential mapping, single photon emission computed tomography (SPECT), and echocardiography have been used as well 3–18 . Since the 1980s, magnetocardiographic (MCG) mapping has also been proposed as a noninvasive method for three‐dimensional localization of arrhythmia foci and ventricular preexcitation (VPX) pathways 19–26 .…”

Noninvasive Classification of Ventricular Preexcitation with Unshielded Magnetocardiography and Transesophageal Atrial Pacing and Follow‐Up

“…The anatomy of the atrioventricular junction was classified according to the consensus statement published in 1999 16 . Seven ablation‐based ECG algorithms 1–7 were applied and the ECG localization of VPx was arbitrarily defined as: (1) unequivocal, when an agreement of ≥5 out of the 7 algorithms was reached, (2) uncertain, with an agreement of 4 out of 7 algorithms, or (3) unreliable, with an agreement of ≤3 out of 7 algorithms.…”

“…The 12‐lead electrocardiogram (ECG) is the simplest noninvasive method of accessory pathways (AP) localization. However, the accuracy of ECG classification of ventricular preexcitation (VPx) varies widely 1–7 . In a recent report, 8 the concordance among 3 ECG algorithms 1,2,7 was, on average, 81% (range 4%–88%) for free wall, and as low as 25%–28.6% for paraseptal AP.…”

“…More recent studies have shown that unshielded multichannel MCG provides 3‐dimensional (3D) functional imaging, which is available for multimodal electro‐anatomical integration of EP information, 11,12 and to localize the site of VPx, including during dynamic EP evaluation with TEP. The present study compared the accuracy of MCG to classify VPx, with that reached with 7 ablation‐based ECG algorithms 1–7 and to evaluate the increment in diagnostic accuracy achievable with TEP. A secondary endpoint was to test the reproducibility of MCG when different instrumentations were used during clinical follow‐up.…”