A new method of a pulmonary vein map to identify a conduction gap on the pulmonary vein antrum ablation line

Methods and techniques for increasing the safety and efficacy of pulmonary vein isolation in patients with atrial fibrillation

The most common type of sustained arrhythmia is atrial fibrillation (AF). Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for atrial fibrillation, which has emerged as the primary therapeutic strategy for atrial fibrillation patients. Unfortunately, about one-third of patients experience recurrent atrial arrhythmias after the procedure.

Novel Clue to Locate Conduction Gaps in the Pulmonary Vein Isolation Ablation Line

Background: Several methods have been reported for locating the conduction gap (CG) in the pulmonary vein isolation (PVI) ablation line. However, the value of the interval between far-field atrial potential (FFP) and pulmonary vein potential (PVP) remains unknown.

Methods: Consecutive patients with a CG during observation on the table after PVI were included. The PVP, FFP, and the CG location were evaluated to develop a novel algorithm to identify the CG location in the left superior pulmonary vein. The performance of this novel algorithm was prospectively tested in a validation cohort of consecutive patients undergoing repeat PVI ablation.

Results: A total of 116 patients with atrial fibrillation (AF) were recruited, 56 of whom formed the validation cohort. The interval between FFP and PVP of the left superior pulmonary vein was associated with the CG location, and an interval <5 ms predicted the presence of CG in the upper portion of the ostium with a sensitivity of 92.9% and a specificity of 96.9%. In the prospective evaluation, the interval was able to correctly predict the site of CG in 89.6% of cases.

Conclusions: The interval between FFP and PVP is a novel and accurate index that can be used to predict the CG location in the left superior pulmonary vein. An far-field atrial potential and pulmonary vein potential (FFP–PVP) interval value of ≥5 ms could be used to exclude a CG in the upper portion of the ostium in the majority of patients undergoing AF ablation.

Localization of Residual Conduction Gaps After Wide Antral Circumferential Ablation of Pulmonary Veins

Ablation of atrial fibrillation (AF) is the cornerstone therapy for patients with symptomatic AF resistant to anti-arrhythmic drugs or as first-line therapy, and is based on permanent pulmonary vein (PV) isolation. The presence of a conduction gap in a wide antral circumferential ablation lesion around PVs is often sufficient to transform an initially successful ablation into a procedural failure, thus necessitating a redo intervention. The strategy during a redo procedure is based on the detection and ablation of the reconnection gap. Finding gaps is often simple, but also sometimes challenging, because gaps may be difficult to detect, resulting in unnecessary radiofrequency delivery. The present review aimed to describe the various techniques published thus far to detect residual reconnections along the encircling ablation lines around PVs, to help electrophysiologists to detect and ablate reconnection gaps.

Cardiac mapping and pulmonary vein isolation using a novel ablation catheter with tip minielectrodes

BACKGROUND

Pulmonary vein isolation (PVI) is a standard treatment for atrial fibrillation (AF). Identification of gaps in the ablation line is difficult. Tip-ring electrograms from ablation catheters represent relative large areas of myocardial tissue. Recently, an ablation catheter with three minielectrodes (ME) on the catheter tip with closer interelectrode spacing was introduced. The aim of our study was to evaluate the novel electrodes during PVI.

METHODS

PVI was performed with an irrigated ablation catheter equipped with conventional electrodes and three additional radial tip electrodes. Detection of pulmonary vein potentials (PVPs), local signal amplitude, amplitude reduction during ablation, and loss of capture after ablation were compared between the ME and the conventional tip-ring electrodes.

RESULTS

Thirty-one patients (mean age 67.8 ± 10.3 years, 45.2 % men) were included. A total of 306 mapping/lesion points were analyzed. A PVP was significantly more often obtained with the ME compared to the conventional tip-ring electrodes (99.2% vs 83.5%, P < 0.001). Local amplitude was significantly higher on the ME (0.8 ± 0.6 mV vs 0.67 ± 0.46 mV, P  =  0.003). Amplitude reduction during 1 RF pulse was significantly greater on the ME (82.9 ± 19.5% vs. 61.8 ± 26.9%, P < 0.001). During pace mapping, loss of capture after 1 RF pulse was observed significantly more often on ME (98.3% vs 63.3%, P < 0.001).

CONCLUSION

Signal amplitude is higher and sensitivity during PVP mapping and ablation is increased when ME are used. ME may facilitate catheter ablation of AF in the future.

Signal Reconstruction of Pulmonary Vein Recordings Using a Phenomenological Mathematical Model: Application to Pulmonary Vein Isolation Therapy

Atrial fibrillation (AF), the most prevalent cardiac arrhythmia, is commonly initiated by ectopic beats originating from a small myocardial sleeve extending over the pulmonary veins. Pulmonary vein isolation therapy attempts to isolate the pulmonary veins from the left atrium by ablating tissue, commonly by using radiofrequency ablation. During this procedure, the cardiologist records electrical activity using a lasso catheter, and the activation pattern recorded is used as a guide toward which regions to ablate. However, poor contact between electrode and tissue can lead to important regions of electrical activity not being recorded in clinic. We reproduce these signals through the use of a phenomenological model of the cardiac action potential on a cylinder, which we fit to post-AF atrial cells, and model the bipolar electrodes of the lasso catheter by an approximation of the surface potential. The resulting activation pattern is validated by direct comparison with those of clinical recordings. A potential application of the model is to reconstruct the missing electrical activity, minimizing the impact of the information loss on the clinical procedure, and we present results to demonstrate this.

Atrial mapping during pulmonary vein pacing: a novel maneuver to detect and close residual conduction gaps in an ablation line

BACKGROUND

Location of residual conduction gaps on ablation lines around pulmonary veins (PV) is challenging, and several maneuvers have been described. Atrial mapping during PV pacing-the "pace and map" maneuver-could localize gaps.

METHODS AND RESULTS

We prospectively studied 209 patients undergoing PV isolation at a single institution over a 25-month period. In 24 (11.4 %) patients, 26 PV remained connected after an ablation line and an initial conventional gap closure protocol. The atrial side of the ablation line was mapped with the ablation catheter during PV pacing, and the earliest site was considered a gap site. Ablation at these gap sites resulted in bidirectional PV conduction block in 22 PV (85 %) in 21 patients (88 %), after 2.2 ± 1.6 radiofrequency applications and 8.2 ± 4.8 min. Early PV reconnection (≥20 min) occurred in 0 PV (0 %). During a mean follow-up of 12 ± 6 months, eight patients (33 %) had arrhythmia recurrences.

CONCLUSIONS

The "pace and map" maneuver is a relatively simple and efficacious means to identify gaps in ablation lines around PV, focusing on the atrial rather than the PV side of the line. It could be considered among the ways to eliminate residual conduction gaps.

Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate

Cardiac electrophysiology has moved a long way forward during recent decades in the comprehension and treatment of complex cardiac arrhythmias. Contemporary electroanatomical mapping systems, along with state-of-the-art technology in the manufacture of electrophysiology catheters and cardiac imaging modalities, have significantly enriched our armamentarium, enabling the implementation of various mapping strategies and techniques in electrophysiology procedures. Beyond conventional mapping strategies, ablation of complex fractionated electrograms and rotor ablation in atrial fibrillation ablation procedures, the identification and modification of the underlying arrhythmogenic substrate has emerged as a strategy that leads to improved outcomes. Arrhythmogenic substrate modification also has a major role in ventricular tachycardia ablation procedures. Optimisation of contact between tissue and catheter and image integration are a further step forward to augment our precision and effectiveness. Hybridisation of existing technologies with a reasonable cost should be our goal over the next few years.

Long-term results of pulmonary vein antrum isolation in patients with atrial fibrillation: an analysis in regards to substrates and pulmonary vein reconnections

AIMS

To examine the impact of left atrial (LA) low-voltage zones (LVZs) on atrial fibrillation (AF) recurrence after pulmonary vein antrum isolation (PVAI) without LA substrate modification.

METHODS AND RESULTS

Seventy-six patients with AF (paroxysmal/persistent 65/11) were prospectively enroled. Left atrial voltage maps were constructed during sinus rhythm using NavX to identify LVZs (<0.5 mV), and PVAI without any LA substrate modification was performed using an open-irrigation catheter. After PVAI, 20 mg of adenosine triphosphate (ATP) was injected. Adenosine triphosphate-induced PV reconnections were eliminated by touch-up ablation when unmasked. Voltage maps revealed LVZs in 24 patients (32%) and no LVZs in 52 (68%). During 24 ± 7 months of follow-up, 15 patients (63%) with LVZs and 10 (19%) without had AF recurrences off antiarrhythmic drugs (log-rank P < 0.001). A multivariate logistic regression analysis revealed that LVZ areas [odds ratio (OR): 1.12 per 1 cm(2), 95% confidence interval (CI): 1.04-1.23, P = 0.001] and ATP-induced reconnection (OR: 2.08, 95% CI: 1.01-4.91, P = 0.046) were significant predictors of recurrence. In those with LVZs, the LVZ area was strongly correlated with the LA body volume (r = 0.81, P < 0.001) and a unique predictor of recurrence (OR: 1.17 per 1 cm(2), 95% CI: 1.01-1.55, P = 0.031), while in those without an LVZ, ATP-induced PV reconnection was a unique predictor (OR: 3.24, 95% CI: 1.15-15.39, P = 0.025).

CONCLUSION

The LVZ area was an independent predictor of recurrence after PVAI without any LA substrate modification. Adenosine triphosphate-induced PV reconnection was also an independent predictor, especially in those without LVZs.

Anatomical and electrophysiological variations of Koch's triangle and the impact on the slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia: a study using 3D mapping

OBJECTIVE

This study aimed to reveal individual variations in Koch's triangle using NavX and to evaluate the efficacy of the NavX-guided slow pathway ablation.

METHODS

A regional geometry around Koch's triangle was constructed in 42 consecutive patients with atrioventricular nodal reentrant tachycardia (AVNRT), and a bipolar electrogram map was created with 72 ± 30 sampling points during sinus rhythm to identify sites with Haissaguerre's slow potentials (SPs) and His bundle electrograms (HBEs) to examine the anatomical and electrical variations. Radiofrequency ablation was performed at the most prominent SP recording site. The acute results and long-term outcome were examined in comparison to another 42 consecutive patients who underwent a conventional fluoroscopy-guided slow pathway ablation in the previous months.

RESULTS

The size of Koch's triangle and the coronary sinus ostium varied over a wide range of 132 to 490 and 69 to 346 mm(2), respectively. HBEs were recorded linearly along the antero-septal right atrium (n = 29) or deviated downward toward the midseptum (n = 13, 31 %). The SPs were always distributed below the lowest HBE recording site. The NavX-guided ablation eliminated AVNRT with a median of 1 radiofrequency pulse, 9.1 ± 4.6 min of fluoroscopy, and 49 ± 14 min of procedure time, all of which were significantly smaller than those in fluoroscopy-guided ablation. No procedure-related complications or long-term recurrence was noted in either group.

CONCLUSION

Koch's triangle varies in terms of the size and electrogram distribution, and the NavX-guided slow pathway ablation overcomes the diversity and seems more effective than fluoroscopy-guided ablation.

Association between changes in coronary artery circulation and cardiac venous retention: a lesson from cardiac computed tomography

To use computed tomography (CT) image data to measure a potential association between the implantation of coronary artery bypass grafts (CABG) and changes in the coronary venous system has not yet been examined. In 112 (aged 59.4 ± 9.0; 45F) patients (pts.), a 64-slice CT angiography was performed. Patients were divided into 2 groups: CABG (56 pts.) and control (56 pts.)—without changes in coronaries. In each case, ten multi-planar reconstructions (MPR) and 3D volume rendering reconstructions using a 2 mm layer with ECG-gating, helical pitch: 12.8; rotation time: 0.4 s and average tube voltage: 135 kV at 380 mA. The visualization of the coronary veins was independently graded by 2 experts trained in CT. In the CABG group, the average number of visible coronary veins was 5.3 ± 1.3, while in the control group it was 3.1 ± 1.1 (p < 0.001). Statistical differences were also observed for the following coronary veins: posterolateral (control 2.1 ± 1.9 vs. CABG 2.9 ± 1.9; p < 0.05), lateral (control 2.2 ± 1.7 vs. CABG 3.1 ± 1.3; p < 0.01) and anterolateral (control 0.5 ± 0.9 vs. CABG 1.3 ± 1.0; p < 0.001). Implantation of CABG influences the coronary venous system. In patients after CABG, the number of identifiable coronary veins is significantly higher as compared to that in subjects without changes in coronaries. This might suggest an association between changes in coronary artery circulation and cardiac venous retention.

Three-dimensional mapping of cardiac arrhythmias - string of pearls -

The evolution of 3-dimensional (D) mapping systems has contributed to improved procedures for ablation of complex tachyarrhythmia in terms of providing detailed anatomical information along with the ability to integrate with pre-acquired computed tomography/magnetic resonance imaging/intracardiac echocardiography images, reducing the radiation exposure, and producing activation and substrate maps. 3-D mapping systems are categorized as magnetic based vs. impedance based according to the catheter location technology, and are also classified as contact based vs. non-contact based according to the data collection technology. Contact-based mapping systems are used widely, in which a series of electrograms is taken sequentially in contact with the heart, thus requiring a relatively stable and sustained arrhythmia to create an activation map. Non-contact mapping systems, however, allow a beat-to-beat analysis of the activation even in non-sustained, polymorphic, or hemodynamically intolerant tachycardia. In this article, the clinical utility of 3-D mapping systems is discussed based on the literature and on experience, with particular emphasis on the non-contact mapping system.