Qi Jin

Acute and long term outcomes of catheter ablation using remote magnetic navigation for the treatment of electrical storm in patients with severe ischemic heart failure

BACKGROUND Catheter ablation with remote magnetic navigation (RMN) can offer some advantages compared to manual techniques. However, the relevant clinical evidence for how RMN-guided ablation affects electrical storm (ES) due to ventricular tachycardia (VT) in patients with severe ischemic heart failure (SIHF) is still limited. METHODS Forty consecutive SIHF patients (left ventricular ejection fraction, 21 ± 6.9%) presenting with ES underwent ablation using RMN. All the patients received implantable cardioverter-defibrillators (ICDs) either before or after ablation. Acute ablation success was defined as noninducibility of any sustained monophasic VT at the end of the procedure. Long-term analysis addressed VT recurrence, ICD therapies and all-cause death. ES was acutely suppressed by ablation in all patients. RESULTS Acute ablation success was obtained in 32 of 40 (80%) patients. The procedure time and fluoroscopy time were 105 ± 27 min and 7.5 ± 4.8 min respectively. No major complications occurred during procedures. During a mean follow-up of 17.4 months, 19 patients (47.5%) remained free of VT recurrence. The percentage of patients receiving ICD shocks after ablation was lower than before ablation (30% vs 69%, P<0.01). The mean number of ICD shocks per individual per year was reduced from 4.3 before ablation to 1.9 after ablation (P<0.05). Ten patients died during follow-up. CONCLUSIONS Acute catheter ablation with RMN is safe and effective to suppress ES in SIHF patients. RMN-guided catheter ablation can prevent VT recurrence and significantly reduce ICD shocks, suggesting that this strategy can be used as an alternative therapy for VT storm in SIHF patients with ICDs.

Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

Objective: We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Methods: Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal probrain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Results: Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%–40% (for all comparisons, P<0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. Conclusions: RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

Endocardial focal activation originating from Purkinje fibers plays a role in the maintenance of long duration ventricular fibrillation.

Aim To determine the role of repetitive endocardial focal activations and Purkinje fibers in the maintenance of long duration ventricular fibrillation (LDVF, VF>1 minute) in canine hearts in vivo. Methods The study was conducted in electrophysiological laboratory of Shanghai Ruijin hospital from July 2010 to August 2012. A 64-electrode basket was introduced through a carotid artery into the left ventricle (LV) of 11 beagle dogs for global endocardial electrical mapping. In the Lugol’s solution group (n = 5), the subendocardium was ablated by washing with Lugol’s solution. In the control group, (n = 6) saline was used for ablation. Before and after saline or Lugol ablation, we determined QRS duration and QT/QTc interval in sinus rhythm (SR). We also measured the activation rates in the first 2 seconds of each minute during 7 minutes of VF for each group. If VF terminated spontaneously in less than 7 minutes, the VF segments used in activation rate analysis were reduced accordingly. Results At the beginning of VF there was no difference between the groups in the activation rate. However, after 1 minute of LDVF the Lugol’s solution group had significantly slower activation rate than the control group. In the control group, all episodes of LDVF (6/6) were successfully sustained for 7 minutes, while in the Lugol’s solution group 4/5 episodes of LDVF spontaneously terminated before 7 minutes (4.8 ± 1.4 minutes) (P = 0.015). In the control group, at 5.1 ± 1.3 minutes of LDVF, a successive, highly organized focal LV endocardial activation pattern was observed. During this period, activations partly arose in PF and spread to the working ventricular myocardium. Mapping analysis showed that these events were consistent with repetitive endocardial focal activations. No evidence of similar focal activations was observed in the Lugol’s solution group. Conclusions Repetitive endocardial focal activations in the LV endocardium may be associated with activation of subendocardial PFs. This mechanism may play an important role in the maintenance of LDVF.

Efficacy and Safety of Atrial Fibrillation Ablation Using Remote Magnetic Navigation: Experience from 1,006 Procedures.

The objective of this study was to assess the procedural outcomes of catheter ablation guided by remote magnetic navigation (RMN) in a large cohort of patients with paroxysmal atrial fibrillation (PAF) and persistent AF (PerAF).

Mapping strategy for multiple atrial tachyarrhythmias in a transplant heart

BackgroundDifferent atrial arrhythmias can coexist in the recipient and donor atria after heart transplantation.Case presentationWe report an unusual case of a patient with three different types of atrial arrhythmia after heart transplantation: an atrial fibrillation in the recipient atria, and a cavotricuspid isthmus dependent atrial flutter and a focal atrial tachycardia in the donor atria. 3D electroanatomical mapping and ablation were guided by remote magnetic navigation (RMN). Atrial fibrillation continued in the recipient atria even after the donor heart was converted to sinus rhythm by ablation.ConclusionsIt is critical to understand the surgical anatomy of a bi-atrial anastomosis and its relevant electrical activation pattern before ablation. Appropriate electroanatomical mapping strategy with RMN can facilitate the successful ablation of post-transplant atrial arrhythmias.

Defibrillation Threshold Varies During Different Stages of Ventricular Fibrillation in Canine Hearts

BACKGROUND Recent studies have shown that short duration ventricular fibrillation (SDVF) and long duration ventricular fibrillation (LDVF) are maintained by different mechanisms. The objective of this study is to evaluate how the defibrillation threshold (DFT) varies over the duration of fibrillation since the mechanism of VF maintenance changes as VF progresses. METHODS Twelve canines were randomly divided into two groups (Group A and B, n=6 each). DFTs were measured three times in each group: SDVF (20s), LDVF (3min in Group A and 7min in Group B) and the first episode of refibrillation after successful defibrillation for LDVF. Two 64-electrode baskets used to globally map the endocardium were deployed into the left ventricle and right ventricle, respectively. RESULTS LDVF-DFT in Group A was significantly higher than that of Group B (628±98V vs 313±81V, P<0.001). In Group B, the DFT of refibrillation was significantly increased compared with the LDVF-DFT (570±199V vs 313±81V, P=0.035) but did not differ from the DFT of refibrillation in Group A (570±199V vs 638±116V, P=0.39). Highly synchronised activation patterns on the left ventricular endocardium were observed between 3 and 7min of LDVF in Group B but not within 3min-LDVF in Group A or during refibrillation in each group. CONCLUSIONS DFT varied during different stages of VF. The highly synchronised activation patterns exhibiting after 3min VF might contribute to the decreased LDVF-DFT.

The effects of acute amiodarone on short- and long-duration ventricular defibrillation threshold in canines.

Introduction: Some studies have shown that the defibrillation threshold (DFT) differs between short-duration ventricular fibrillation (SDVF, <1 minute) and long-duration ventricular fibrillation (LDVF > 1 minute). The goal of this study is to evaluate the effects of acute intravenous amiodarone on SDVF-DFT and LDVF-DFT and its possible mechanism as well. Methods: Twelve open-chest dogs were randomly divided into 2 groups (control group, normal saline, 10 mL·kg−1·h−1 maintenance, n = 6; amiodarone group, loading dose 10 mg/kg over 10 minutes, maintenance dose 5 mg·kg−1·h−1, n = 6). VF was electrically induced and recorded with a 12 × 12 unipolar electrode plaque (2-mm spacing) sutured on the left ventricular epicardium and a plunge needle (6 unipolar electrode) inserted in the left ventricular apex. The DFTs of SDVF and LDVF were determined 20 seconds and 3 minutes after VF induction, respectively. Restitution was estimated from activation recovery intervals during pacing from the plaque and plunge needle electrodes. The activation rate was estimated by Fast Fourier Transform analysis of VF at same electrodes. The VF cycle length was defined as the reciprocal of the activation rate. The epicardial and transmural dispersion of the maximal slope of the restitution curve and VF cycle length of SDVF and LDVF were calculated, respectively. Results: In controls, LDVF-DFT was higher than SDVF-DFT (645 ± 61 vs. 520 ± 63 V, P < 0.01). Amiodarone did not significantly alter SDVF-DFTs (496 ± 49 vs. 552 ± 69 V, P > 0.05) but decreased LDVF-DFT by 31% (P < 0.01). Compared with control, amiodarone significantly reduced the maximum slope of the restitution curve (1.12 ± 0.35 vs. 0.81 ± 0.25, P = 0.03) and its epicardial dispersion (0.32 ± 0.07 vs. 0.24 ± 0.04,coefficient of variation, P = 0.017). Amiodarone significantly increased the SDVF-CL (92 ± 8 vs. 99 ± 10 milliseconds, P < 0.01) and epicardial dispersion 0.14 ± 0.06 vs. 0.18 ± 0.05, P < 0.01. Amiodarone did not change the LDVF-CL (228 ± 12 vs. 226 ± 10 milliseconds, P > 0.05) or epicardial dispersion (0.17 ± 0.03 vs. 0.15 ± 0.02, P > 0.05) compared with control. However, the drug significantly decreased the transmural dispersion of LDVF-CL (68 ± 28 vs. 39 ± 14 milliseconds, P < 0.01) without changing the transmural dispersion of SDVF-CL (29 ± 22 vs. 32 ± 30 milliseconds, P > 0.05). Conclusions: Acute amiodarone significantly decreased the LDVF-DFT. The decreased transmural dispersion of LDVF-CL by amiodarone might contribute to the decreased LDVF-DFT.

Prediction and prognosis of ventricular tachycardia recurrence after catheter ablation with remote magnetic navigation for electrical storm in patients with ischemic cardiomyopathy

Ventricular tachycardia (VT) recurrence after catheter ablation for electrical storm is commonly seen in patients with ischemic cardiomyopathy (ICM).

Remote magnetic navigation facilitates the ablations of frequent ventricular premature complexes originating from the outflow tract and the valve annulus as compared to manual control navigation

OBJECTIVE The purpose of this study was to assess the role of remote magnetic navigation (RMN) in the ablation of ventricular premature complexes (VPCs) arising from outflow tracts (OT) and valve annuli by comparing to manual control navigation (MCN). METHODS A total of 152 patients with frequent VPCs were prospectively enrolled. 64 (42%) patients underwent ablation guided by RMN. Acute success rate was defined as the complete elimination and non-inducibility of clinical VPCs during the procedure. RESULTS Overall, acute success rate of RMN group was not different from MCN group (87.5% vs 84.1%, p = 0.56). Compared to MCN group, the fluoroscopic time of OT-VPCs ablation in the RMN group was significantly reduced by 67% (2.9 ± 2.3 min vs 8.9 ± 9.7 min, p = 0.006), and the ablation applications in successful cases were significantly reduced (11 ± 7 vs 15 ± 11, p = 0.018). Compared to MCN, RMN significantly decreased ablation applications (15 ± 9 vs 23 ± 9, p = 0.013) in the acute success rates of ablating VPCs of valve annulus, and has a trend of a higher success rate for VPCs arising from tricuspid annulus (10/11 vs 7/12, p = 0.193). No complications occurred in the RMN group. Three cases of cardiac tamponade and one case of transient atrioventricular block occurred in the MCN group (p = 0.22). After a mean follow up of 16.2 months, 2/56 and 3/74 patients had a recurrence of VPCs in the RMN group and MCN group respectively (p = 0.75). CONCLUSIONS When compared to MCN, RMN-guided ablation for VPCs was just as effective and safe, with the added benefit of reduced fluoroscopic time and fewer ablation applications.

Antifibrillatory effects of renal denervation on ventricular fibrillation in a canine model of pacing‐induced heart failure

What is the central question of this study? In the present study, we investigated the effects of renal denervation on the vulnerability to ventricular fibrillation and the ventricular electrical properties in a rapid pacing‐induced heart failure canine model. What is the main finding and its importance? Renal denervation significantly attenuated the process of heart failure and improved left ventricular systolic dysfunction, stabilized ventricular electrophysiological properties and decreased the vulnerability of the heart to ventricular fibrillation during heart failure. Thus, renal denervation can attenuate ventricular electrical remodelling and exert a potential antifibrillatory action in a pacing‐induced heart failure canine model.