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Electrocardiographic identification of mid-septal accessory pathways in close proximity to the atrioventricular
A Lorga Filho1, E Sosa, M Scanavacca
1Heart Institute, São Paulo, Brazil.
Insights
Electrocardiogram (ECG) findings can predict accessory pathway proximity. A negative delta wave in lead aVF suggests a mid-septal accessory pathway (AP) is near the AV conduction system.
Area of Science:
- Electrophysiology
- Cardiology
- Medical Imaging
Background:
- Mid-septal accessory pathways (APs) are a common cause of supraventricular tachycardia.
- Identifying APs close to the AV conduction system is crucial for successful ablation and preventing heart block.
Purpose of the Study:
- To determine electrocardiogram (ECG) characteristics that predict the proximity of mid-septal accessory pathways (APs) to the atrioventricular (AV) conduction system.
- To correlate ECG findings with the ablation zone of mid-septal APs.
Main Methods:
- Retrospective analysis of ECG data from patients undergoing radiofrequency (RF) catheter ablation of mid-septal APs.
- Division of the mid-septal area into three zones based on the 40-degree right anterior oblique view.
- Analysis of delta wave polarity and R/S transition in precordial leads, comparing patients ablated in posterior (zone 3) versus anterior/intermediate zones (zones 1 and 2).
Main Results:
- All patients exhibited a positive delta wave in leads I, II, aVL, and a negative delta wave in leads III and aVR.
- R/S transition in lead V2 occurred in 80% of patients.
- A negative delta wave in lead aVF was significantly associated with APs ablated in zone 3 (posterior), indicating closer proximity to the AV conduction system (P = 0.03).
Conclusions:
- The delta wave polarity in lead aVF is a valuable ECG predictor of mid-septal AP location relative to the AV conduction system.
- A positive or isoelectric delta wave in lead aVF suggests the mid-septal AP is in close proximity to the AV conduction system, guiding ablation strategies.
Abstract:
In order to identify ECG characteristics of overt mid-septal accessory pathways (APs) predictive of close proximity to the AV conduction system we analyzed data from patients who underwent successful RF catheter ablation of a mid-septal AP. Mean patient age was 31 +/- 16 years, and 13 were male. The 40 degrees right anterior oblique view was used to divide the mid-septal area into 3 zones: 1 (anterior portion); 2 (intermediate); and 3 (posterior portion). The 12-lead ECG was analyzed with regard to delta wave polarity and R/S transition in the precordial leads. The findings from patients ablated at zone 3 were compared to those at zones 1 and 2. All patients had a positive delta wave in the leads I, II, aVL, and negative delta wave in the leads III and aVR. The R/S transition occurred in lead V2 in 80% of patients. The delta wave in lead aVF was the only ECG characteristic that correlated with the AP ablation zone. Six of 8 patients ablated at zone 3 had a negative delta wave in lead aVF while 6 out of 7 patients ablated at zone 1 or 2 had a positive or isoelectric delta wave in lead aVF (P = 0.03). A positive or isoelectric delta wave in lead aVF identifies mid-septal AP in close proximity to the AV conduction system.