Objectives Spike and discrete potentials have been documented at optimal ablation site (OAS) in patients with idiopathic ventricular arrhythmias arising from the right ventricular outflow tract (RVOT-IVAs). However, characteristics of isolated diastolic potentials (IDPs) and its role in arrhythmogenesis were currently unknown in those patients.
Methods Twenty-three consecutive patients with RVOT-IVAs and ten control subjects were studied. Electroanatomical mapping (EAM) was performed in RVOT during sinus rhythm. The discrete, low amplitude potentials separated from ventricular activations by an isoelectric segment and independent with P and T waves were defined as IDPs. The electrophysiological characteristics of IDPs and its relation to OAS were examined.
Results IDPs were recorded in RVOT in all patients and in one control subject. The mean maximal amplitude of the IDPs was 0.3 ± 0.1mV. IDPs were mainly located in transitional-voltage zone (0.5–1.5mV), with the size of 1.5 ± 0.3cm2 and mean distance from pulmonary valve of 1.4 ± 0.3cm. According to the interval between IDPs and ventricular activation, two patterns during sinus rhythm were distinguished at baseline: constant and automatic. Constant IDPs was characterised by decremental property. The OAS was within the IDPs area in 18 patients (78.3%) and was on the borderline of the IDPs area in the remaining 5 patients. There was no difference in these parameters between patients whose OAS was within or on the border (P > 0.05).
Conclusions IDPs can be recorded in patients with RVOT-IVAs and the OAS was always located either within or on the border area of IDPs. While the precise mechanism of generation remains to be clarified, our observations indicate that IDPs may be related to the VAs origin/breakout. Mapping them might be a useful tool in guiding successful ablation in the RVOT-IVAs.