PO-04-141 PRECISE LOCALIZATION OF ORIGINS IN VENTRICULAR ARRHYTHMIAS FROM PULMONARY SINUS CUSPS: INSIGHTS INTO DISCRETE POTENTIAL AT ANATOMIC VENTRICULO-ARTERIAL JUNCTION

Abstract

The sharp high-frequency discrete potentials recorded during mapping of ventricular arrhythmias from pulmonary sinus cusps (PSCs) often indicate site of origin and target for ablation, which can be located beyond or below pulmonary sinuses. To understand the site of origin by investigating the relationship between the discrete potentials and local anatomic structures in PSC arrhythmias. Patients undergoing ablation for idiopathic ventricular arrhythmias from PSC using 3-D mapping system and intracardiac echocardiography were enrolled. The end of ventricular myocardial extension (VME) at anatomical ventriculo-arterial junction was mapped during sinus rhythm, with its distance to pulmonary valve attachment at each sinus bottom and junction measured. When discrete potentials were observed beyond pulmonary cusps, initial radiofrequency was delivered using supravalvular approach mapping of ventricular arrythmias, while conventional approach was used for targeting the potentials at interleaflet triangles. The anatomical relationship between sites of discrete potentials, valve attachment and VME was studied. From 21 patients with ventricular arrhythmias from PSCs, all had ventricular myocardium extending beyond the level of each sinus bottom and junction as well, with different VME length over 3 cusps (P<0.01). The longest VME was seen in left pulmonary cusp which was 13.3±4.7mm over the valve attachment, while the shortest was found in anterior cusp (Panel A). Typical near-field discrete potentials preceding local electrograms during ventricular beats were found in 17 patients with timing of 36.5±7.3mm before QRS onset, all proven as effective targets for ablation (Panel B). The potentials could be found beyond pulmonary cusps in 12 patients (8 in the left cusp, panel C) while at the interleaflet triangles in 7 cases. In 2 patients, they can be recorded from both above and below the valve. The sites of origin were close to VME with a mean distance of 2.3±2.8mm. Acute success were achieved in all patients with a success rate of 88.2% after a 6-month follow up period. In the cases of idiopathic ventricular arrhythmias from PSCs, ventricular myocardial extends beyond all pulmonary cusps with different length over each sinus. The sites of origin have close anatomical relationship with VME, which can be close to or distant from pulmonary valves. It is reasonable to select proper approach based on the location of discrete potentials.