To correlate the antegrade effective refractory period of the accessory pathway with its anatomical location in the heart. To investigate whether the accessory pathway location can predict the high risk nature of the accessory pathway
The Wolf-Parkinson-White (WPW) syndrome is a clinical entity characterized by the presence of ≥1 accessory pathways between the atria and the ventricles pre-disposing patients to arrhythmias. Anterograde conduction through the accessory pathway leads to preexcitation of the ventricles and a delta wave in the ECG. The prevalence of preexcitation in the general population has been estimated to be 1 to 3 in 1000 individuals. Although most asymptomatic patients with pre-excitation have a good prognosis, there is also a lifetime risk of malignant arrhythmias and SCD, estimated to be 0.1 % per patient year. * More worrisome is the fact that this event can be the first manifestation of the disease in up to 53 % of patients. * Atrial fibrillation (AF) can be a life-threatening arrhythmia in the WPW syndrome if the AV AP has a short anterograde refractory period (RP), allowing too many atrial impulses to be conducted to the ventricle. * This will result in very high ventricular rates with possible deterioration into ventricular fibrillation (VF) and sudden death. * Parameters proved to indicate high risk AP include AP effective refractory period \<240 ms, shortest preexcited RR interval \<250 ms * Certain Locations were thought to be associated with higher risk of the accessory pathway like Septal localization which was significantly more frequent in patients with VF when compared with individuals with no VF but the overall number of patients is limited . . These debatable relations between AP location and its risk stratification was not extensively studied in larger scale studies….
Study Type
OBSERVATIONAL
Enrollment
35
To assess whether the AP is of high risk or not, for all patients the AERP of the AP will be determined by one of the following ways: The cycle length at which abrupt and complete loss of pre-excitation occurs during exercise test. If this didn't happen, the patient will be subjected to invasive electrophysiologic study.. The Antegrade refractory period of the AP is measured during EPS as the shortest cycle length with one-to-one conduction over the AP by incremental atrial stimulation after which the QRS becomes narrow or no conduction occurs due to block of the impulse in the AP. The shortest pre-excited R-R interval during spontaneous or induced AF.
the antegrade refractory period during invasive EPS done for the patients
the values will be correlated to the site of the AP diagnosed be EPS.. according to the previous studies and the current guidelines, if the refractory period is \< 250 ms, this is considered a high risk AP
Time frame: 2 hours
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