Effects Of WPW Syndrome On Terminal QRS Vector Observed In ECG And3-dimension Vector

ObjectiveIn WPW syndrome, the change of initial QRS vector is usually noted.However, there is little information about the change of terminal QRS vector. Inthis study we intend to make a comparison between3-dimension vector andelectrocardiogram (ECG) in observing the effects of Wolff-Parkinson-Whitesyndrome (WPW syndrome) on terminal QRS vector. Furthermore, therelationship between the change of terminal QRS vector and accessorypathway (AP) as well as the initial QRS vector will be analyzed.MethodsThe30patients who were proved to have a single accessory pathwaycapable antegrade conduction by ablation were included. All the patients weredivided into9groups based on the AP location. As to the ECG, the change ofterminal QRS vector was observed in each lead before and after ablation. In3-dimensional vector, the change of terminal QRS vector was observed in3-dimensional solid surface before and after ablation. The relationship betweenthe change of terminal QRS vector and AP location as well as the change ofinitial QRS vector was analyzed in ECG and3-dimensinal vector, respectively.Results1. All30patients had a change in terminal QRS vector in ECG and 3-dimensional vector. The change of terminal QRS vector was related to theinitial QRS vector: the change of terminal QRS vector was identical to thepolarity of initial QRS vector before ablation. The change of terminal QRS vectorwas association with the AP location: if the AP was located in left-side ventricle,the ECG showed a decrease in the amplitude of terminal S wave (or appear ther' wave) in lead V1, the3-dimensional vector showed a increase of horizontalangles. Inversely, the AP was located in right-side ventricle. If the AP located inthe anterior region (LA,LL), the ECG showed a decrease in the amplitude of theterminal R wave (or an increase in the amplitude of terminal s wave) in leads IIIand aVF, the3-dimensinal vector showed a decrease in the angle of altitude.2. The agreement between the change of terminal QRS vector and theinitial QRS vector in3-dimentional vector was higher in comparison to theagreement between the terminal QRS vector and initial QRS vector in any leadof ECG (91.65%Vs74.4%, P<0.01). The consistency rate between the changeof terminal QRS vector and initial QRS vector was higher than that in any lead ofECG (0.846Vs0.559?P<0.01).ConclusionPre-excitation not only affects the initial vector, but also affects QRSterminal vector and morphology. The change of terminal QRS vector is relatedto the AP location and the initial QRS vector. The effect of WPW syndrome onQRS initial and terminal vector is showed more intuitive and easy incomparisonto ECG. The diagnosis of WPW syndrome and the analysis of AP location in3-dimensional vector is superior than that in ECG. ObjectiveAlthough the pre-excitation syndrome can affect terminal QRS vector, therehas been little information concerning that. The study further explores the effectof antegradely conducting accessory pathway (AP) on terminal vector.Methods158patients who were proved to have a single AP capable antegradeconduction by ablation were included. In150patients (overt group), the classicalpre-excitation was recorded before ablation. In8patients (latent group) withoutdelta wave before ablation, the pre-excitation was induced duringtransesophageal atrial pacing. Overt group: ECGs before and after ablationwere examined. The change of terminal QRS vector was observed, whichrelationship with AP location and delta wave was analyzed. Latent group: ECGsbefore and after ablation as well as during atrioventricular reentrant tachycardiawere analyzed. In patients with a change of terminal vector, the relationshipbetween V wave derived from target site and the initial QRS complex wasanalyzed.Results1. Overt group: All patients had a change in terminal vector, which wasrelated to delta wave and AP location. 2. latent group: Of8patients2cases had a change in terminal vector. TheV wave derived from target site occurred almost simultaneous with the initialQRS complex.ConclusionPre-excitation not only affects the initial vector, but also affects QRSterminal vector and morphology. Delta wave represents that AP conduction isfaster than normal conduction. The change of terminal vector is the sign of APconduction, which is helpful for the diagnosis of pre-excitation without evidentdelta wave and incomplete latent pre-excitation.