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Background: Open‐window mapping (OWM) is a novel automated mapping method for catheter ablation of an accessory pathway (AP), in which the local signal is annotated with window‐of‐interest parameters to analyze both atrial and ventricular signals. This study aimed to determine the utility of OWM in visualizing the location and width of APs in patients with Wolff‐Parkinson‐White syndrome. Methods: This two‐center study enrolled 30 patients (20 males; mean age: 56 years, interquartile range [IQR]: 22–69 years) who underwent high‐density OWM with the extended early‐meets‐late (EEML) algorithm using a 20‐electrode, 5‐spline catheter (PENTARAY, Biosense Webster). The lower threshold of the EEML was set to adjust the EEML gap to match the propagation mapping, and broad APs were defined as an EEML gap > 1 cm. Results: The median mapping points, mapping time, and lower threshold of the EEML were 2482 (IQR: 1755–4000) points, 23 (IQR: 15–30) min, and 23 (IQR: 18–25), respectively. All 30 APs (24 in the mitral annulus and 6 in the tricuspid annulus) were successfully eliminated. Of these APs, 21 (70%) were eliminated by the first radio frequency (RF) application. OWM revealed broad APs in 11 patients (37%), in four of whom (36%) the first RF application achieved a loss of AP conduction (vs. 90% of patients without broad APs; p =.004). Conclusion: OWM facilitates the visualization of the location and width of APs, which may be particularly useful for predicting whether multiple RF applications are required for broad APs. [ABSTRACT FROM AUTHOR]

Introduction: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His-bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His-bundle in comparison with right ventricular outflow tract (RVOT)-VT/VPCs. Methods and Results: Ninety RV-VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His-bundle. Ten patients had foci near the His-bundle (HIS group), with the His-bundle local ventricular electrogram preceding the QRS onset by 15–35 msec (mean: 22 msec) and His-bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 ± 0.6 mV) was significantly lower than that of the RVOT group (1.7 ± 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group. Conclusion: VT/VPCs originating near the His-bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency catheter ablation (RFCA) can eliminate most idiopathic repetitive monomorphic ventricular tachycardias (RMVTs) originating from the right and left ventricular outflow tracts (RVOT, LVOT). Here, we describe the electrophysiological (EP) findings of a new variant of RMVT originating from the mitral annulus (MAVT). Methods and Results: MAVT was identified in 35 patients out of 72 consecutive left ventricular RMVTs from May 2000 to June 2004. All patients underwent an EP study and RFCA. The sites of origin of the MAVT were grouped into four groups according to the successful ablation sites around the mitral annulus. Group I included the anterior sites (n = 11), group II the anterolateral sites (n = 9), group III the lateral sites (n = 6), and group IV the posterior sites (n = 9). The MAVTs were a wide QRS tachycardia with a delta wave-like beginning of the QRS complex. The transitional zone of the R wave occurred between V1-V2 in all cases. The 12-lead electrocardiogram (ECG) pattern might reflect the site of the origin of MAVTs around the mitral annulus. We proposed an algorithm for predicting the site of the focus and the tactics needed for successful RFCA of the MAVT. Conclusions: We described the EP findings of the new variant of RMVT, MAVT. Most MAVTs could be eliminated by RF applications to the endocardial mitral annulus using our proposed tactics. [ABSTRACT FROM AUTHOR]

Introduction: Dual atrioventricular nodal non‐reentrant tachycardia (DAVNNT) is a rare and challenging‐to‐diagnose arrhythmia, without previous reports associating it with a leftward inferior extension (LIE). Methods: Diagnosis was made using adenosine triphosphate (ATP) injection during atrial pacing in a suspected DAVNNT patient. Results: Ablation of the rightward inferior extension was unsuccessful in eliminating DAVNNT; however, subsequent ablation of the LIE successfully eradicated the arrhythmia. Conclusion: This unique case, marked by the first instance of DAVNNT caused by LIE, diagnosed through ATP injection, underscores the utility of this diagnostic approach and broadens the spectrum of our understanding and management of this condition. [ABSTRACT FROM AUTHOR]

We report a case in which endocardial radiofrequency (RF) ablation guided by unipolar intracoronary mapping using a guidewire was an effective therapy for treating VT originating from an epicardial site of the left ventricle. A 55-year-old man with dilated cardiomyopathy was referred for treatment of refractory sustained monomorphic VT. The earliest unipolar electrogram with a near-perfect pace map was identified at segment #8 of the left anterior descending artery utilizing a guidewire through a microtube catheter during the VT. VT was terminated by an endocardial RF application at an upper midventricular septal site that did not have a good pacemap or the earliest electrogram, and that was the most adjacent anatomical endocardial site to the guidewire tip. No VT was clinically observed during a follow up period of 14 months. [ABSTRACT FROM AUTHOR]

Background Phrenic nerve (PN) palsy (PNP) is the most frequent complication of cryoballoon ablation (CBA) of atrial fibrillation (AF). The major complication of this technique seems to be right-sided PN injury (PNI) following ablation of the right pulmonary veins (PVs). We sought to assess the incidence and prognosis of left-sided PNI during CBA. Methods CBA was performed in 448 patients with AF. During the ablation of the left-sided PVs, the PN was paced from the left subclavian vein with a pacing output just exceeding the threshold by 10 ∼ 20%. The right and left arm 12-lead electrocardiogram electrodes were positioned 5 cm above the xiphoid process and 16 cm along the left costal margin. The amplitude of the compound motor action potentials was recorded during the CBA. Results Two thousand one hundred seventy-eight CBA applications were delivered in 1,094 left-sided PVs. PNI occurred in 29 patients (6.5%); the PN could be captured by an increasing pacing output in 21 patients (4.7%), and premature termination of the freezing was required to avoid PNP in eight patients (1.8%). The PN function recovered before discharge; however, it took 7 months for one patient to completely recovery from the PNP. Conclusions Left-sided PNP could be provoked during a left-sided CBA procedure. Assessment of the left PN during the CBA was necessary to prevent left-sided PNP. [ABSTRACT FROM AUTHOR]

Background: Despite similar QRS morphology, idiopathic repetitive monomorphic ventricular tachyarrhythmias (VTs) of left ventricular outflow tract (LVOT) are known to have the variants of different adjacent origins, including the aorto-mitral continuity (AMC), anterior site around the mitral annulus (MA), aortic sinus cusps (ASC), and epicardium. However, the electrocardiographic characteristics of those variants previously have not been evaluated fully. Methods and Results: Based on the mapping site and successful ablation in 45 consecutive patients with LVOT-VTs, we classified them into VTs of AMC (n = 3), MA (n = 8), ASC (n = 32), and epicardial (n = 2) origins. In all patients, we performed activation mapping and an electrocardiographic analysis. All AMC-VTs patients had monophasic R waves in almost all the precordial leads, while those with anterior MA-VTs had an Rs pattern in some precordial leads except for lead V6, and those with ASC-VTs had a variable transitional zone in leads V1–4. There was no S wave in lead V6 in any group except for one patient with anterior MA-VTs. The intrinsicoid deflection time in the AMC-VTs patients and anterior MA-VTs patients was significantly greater than in those with ASC-VTs (P < 0.05). There was no significant difference in the R-wave amplitude in the inferior leads among the groups. Successful radiofrequency catheter ablation (RFCA) was achieved in all patients except for in those with epicardial origin VT. Conclusions: Despite many morphological similarities, the LVOT-VTs originating from the AMC, anterior MA and ASC could be identified by our proposed electrocardiographic characteristics in order to safely perform RFCA. [ABSTRACT FROM AUTHOR]