Anatomical approach to suppression of para-Hisian ventricular arrhythmias with changes in QRS morphology after ablation at the earliest activation site.

BACKGROUND: The anatomical approach for the management of para-Hisian ventricular arrhythmias (VAs) with QRS morphological changes after catheter ablation (CA) has not been well investigated. OBJECTIVE: We aimed to evaluate the electrocardiographic and electrophysiological findings and ablation outcomes of para-Hisian VAs with QRS morphological changes after CA. METHODS: Of the 30 patients who underwent CA for para-Hisian VAs at 4 institutions, 10 (33%) had QRS morphological changes after ablation. All 10 patients underwent an anatomical approach, targeting the site anatomically opposite to the site where the QRS morphology had been changed by ablation. We investigated the safety and efficacy of the anatomical approach. RESULTS: Of the 10 patients evaluated, the approach was switched from the right ventricular septum to the left ventricular septum/aortic root in 7 (70%) (RL group) whereas 3 (30%) underwent left-to-right switches (LR group). After CA, the precordial transition zone tended to be earlier in the RL group and later in the LR group. In the RL group, successful VA suppression was achieved, despite suboptimal pace map concordance from the left side or a relatively delayed earliest activation time. Of the 10 patients who underwent an anatomical approach, 8 (80%) had procedural success, and ablation was discontinued in 1 (10%) because of the risk of atrioventricular block. CONCLUSION: The anatomical approach showed promising results regarding safety and efficacy. Therefore, it should be considered when QRS morphological changes are observed during or after CA of para-Hisian VAs.

The R Wave Amplitude in Lead aVL Could Predict Successful Catheter Ablation of Ventricular Arrhythmias Originating below the His Bundle Region of the Right Ventricle.

Radiofrequency catheter ablation (RFCA) to treat ventricular arrhythmias (VAs) originating below the His bundle (HB) region of the right ventricular (RV) septum could impair the atrioventricular node conduction. This study aimed to clarify the parameters of the 12-lead electrocardiography that predict successful RFCA of VAs originating from this region. This study included 20 consecutive patients (13 men; mean age, 68 ± 7 years) with monomorphic VAs in whom the earliest ventricular activation during the VA was below the HB region of the RV septum. According to the ablation results, the patients were divided into two groups: successful ablation (S-group; n = 10) and failed ablation groups (F-group; n = 10). The electrocardiographic parameters during the VAs and RFCA results were assessed. The R wave amplitudes in leads aVL (P = 0.001) and I (P = 0.010) in the S-group were both smaller than those in the F-group. In addition, the S-group had smaller negative deflection amplitudes in leads III (P = 0.002) and aVF (P = 0.003) than the F-group. According to the receiver operating characteristic curve analysis, the most useful electrocardiographic parameter for predicting successful ablation was the R wave amplitude in lead aVL (area under the curve, 0.895; P < 0.001); a cutoff value of < 1.3 mV predicted a successful RFCA with the highest accuracy (sensitivity, 90%; specificity, 80%; positive predictive value, 82%; negative predictive value, 89%). The R wave amplitude in lead aVL was the most useful parameter for predicting a successful RFCA to treat VAs originating below the HB region of the RV septum.

A single premature stimulation from the para-Hisian region unmasked negative involvement of the left anterior fascicle in the verapamil-sensitive ventricular tachycardia with a right bundle branch block and right-axis deviation.

A 33-year-old man had verapamil-sensitive ventricular tachycardia (VT) with a right bundle branch block (RBBB) and right axis deviation. Programmed stimulation from the para-Hisian region induced ventricular tachycardias (VT1 or VT2). VT1 was entrained during pacing from the para-Hisian region. A single para-Hisian stimulation antidromically captured the proximal portion of the left anterior fascicle (LAF), but the cycle length of VT2 remained unchanged. This observation indicated that the upper limb of the LAF was a bystander of the reentry circuit. We have clarified this mechanism with applying a single premature stimulation from the para-Hisian region.

R/S Ratio in Lead III Predicts Successful Ablation of Ventricular Arrhythmias Originating in Para-Hisian Region.

OBJECTIVES: The aim of this study was to investigate the electrocardiographic characteristics of ventricular arrhythmias (VAs) originating near the His bundle (HB) and use the R/S ratio in lead III (RIII/SIII ratio) to predict successful ablation of para-Hisian VAs. BACKGROUND: Catheter ablation for idiopathic VAs near the HB is often challenging, and data are limited. METHODS: The present study included 134 consecutive patients undergoing catheter ablation of para-Hisian VAs. The electrocardiographic characteristics in these patients were retrospectively evaluated with successful ablation and failed ablation. RESULTS: Successful ablation was achieved in 115 (85.8%) of the 134 patients. There was no significant difference in QRS duration between the successful and the failed ablation groups. The ablation success rate was significantly lower for para-Hisian VAs with a predominantly positive R wave in lead III than those with a predominantly negative S wave in lead III. The significant factor associated with successful ablation was the RIII/SIII ratio. The RIII/SIII ratio ≤1.1 predicted the successful ablation of para-Hisian VAs with high sensitivity (80.9%) and specificity (94.7%). The RIII/SIII ratio of >1.2 had high sensitivity (100.0%) and specificity (82.8%) to predict the distance <5 mm from the site of origin of para-Hisian VAs to the site recording the largest HB potential. CONCLUSIONS: The RIII/SIII ratio was a helpful predictor of the successful ablation of VAs originating in the vicinity of the HB. This may be useful for planning ablation of para-Hisian VAs and minimizing the risk of inadvertent atrioventricular block.

Safety and efficacy of first-line cryoablation for para-hisian ventricular arrhythmias using a cryomapping protocol approach: A case series.

A first-line cryoablation for para-Hisian VAs using a strict cryomapping protocol is useful and safe, even if the His bundle potential is recorded on the ablation catheter.

Catheter ablation of right-sided para-Hisian ventricular arrhythmias using a simple pacing strategy.

BACKGROUND: Ablation of para-Hisian ventricular arrhythmias (PH-VAs) is challenging because of the close relationship of the origin site and His bundle. Using pacing techniques to differentiate the near-field from far-field His activations, thereby avoiding atrioventricular block, has been reported in patients with para-Hisian accessory pathways. OBJECTIVES: We applied the same pacing technique and 3-dimensional mapping to guide radiofrequency (RF) ablation in patients with right-sided PH-VAs and investigated the clinical outcome of such cases. METHODS: Fourteen patients with right-sided PH-VAs were included in this study. The earliest activation sites were confirmed in the right ventricle on the 3-dimensional map. Pacing with different outputs was performed at the largest His potential site (P1) and the earliest activation site (P2). If the minimum His bundle-right bundle branch-captured output at P2 was higher than that at P1, RF ablation was performed at the site. RESULTS: All the patients in this study had monomorphic premature ventricular contractions (PVCs) with a mean QRS duration of 118.3 ± 8.1 ms. A His-right bundle branch potential with an amplitude of 0.05 ± 0.02 mV was recorded at P2, with a mean distance of 5.97 ± 1.84 mm away from P1. PVCs were successfully eliminated in 13 of 14 patients (92.9%). One patient exhibited persistent right bundle branch block after ablation, and 1 recurrence of ablated PVCs occurred during a median follow-up period of 15 months. CONCLUSION: Using a simple pacing technique to evaluate the safety of RF energy application led to a high success rate of RF catheter ablation of right-sided PH-VAs without atrioventricular block.

Safety and Efficacy of Cryoablation in Patients With Ventricular Arrhythmias Originating From the Para-Hisian Region.

OBJECTIVES: This study aimed to assess the outcome of cryoablation in patients with ventricular arrhythmias (VAs) originating from the para-Hisian region. BACKGROUND: There are few data regarding the outcome of cryoablation in patients with VAs originating from the para-Hisian region, where there is the risk of injury to the conduction system. METHODS: The study analyzed all patients undergoing cryoablation at the Mayo Clinic (Rochester, Minnesota) as part of an ablation for VAs originating from the para-Hisian region. RESULTS: The study population consisted of 10 patients (64 ± 15 years of age, 7 men). Cryoenergy was applied after an unsuccessful radiofrequency (RF) ablation in 8 (80%) patients. The VAs were successfully ablated with cryoablation in 7 (70%) patients; RF ablation after an unsuccessful cryoablation eliminated the VAs at almost the same location with careful monitoring in 1 patient. The authors could not ablate the actual focus because a transient atrioventricular block developed during cryo- and RF energy applications, which led to an unsuccessful ablation in the remaining 2 patients. A complete atrioventricular block occurred during the cryoenergy application in 1 patient, who needed a permanent pacemaker implantation. There were no VA recurrences in 4 of 8 (50%) patients with procedural success during a median follow-up period of 122 days (interquartile range: 43 to 574 days). CONCLUSIONS: Cryoablation is clinically effective in some patients with VAs originating from the para-Hisian region, where there is the risk of injury to the conduction system, and therefore should be considered as an alternative to or in addition to RF ablation in these cases. Cryoablation requires care because it can also lead to major complications.