Single catheter determination of local electrogram prematurity using simultaneous unipolar and bipolar recordings to replace the surface ECG as a timing reference

Initial negative concordance on unipolar and bipolar electrograms: a novel parameter for localizing the origin of premature ventricular contractions arising from pulmonary sinus cusps

BACKGROUND

The features of the unipolar electrogram (UEGM) and bipolar electrogram (BEGM) have been utilized to identify the site of origin of idiopathic premature ventricular contractions (PVCs) arising from pulmonary sinus cusps (PSCs), but for these PVCs, whether a negative concordance in the initial waves of both EGMs recorded above pulmonary valves can be used as a parameter to localize the origin has not been previously studied. We aimed to assess whether an initial negative concordance (INC) between the UEGM and BEGM might determine the origin of PVCs mapped and ablated within PSCs.

METHODS

Data were collected from 22 patients undergoing successful radiofrequency catheter ablation for symptomatic idiopathic PVCs within PSCs. The morphological features of both the UEGM and the BEGM recorded at all ablation sites were analyzed.

RESULTS

A total of 109 sites within PSCs were ablated in 22 patients with an age (mean ± SD) of 47.2 ± 17.2 years. Ablation resulted in procedural success in all patients. The INC was observed at 18 of 22 (81.8%) successful ablation sites, contrasted with 3 of 87 (3.4%) unsuccessful sites (P < 0.001). The INC was consistent with the outcomes of conventional mapping parameters and proved to be an additional useful predictor of ablation success, with a sensitivity, specificity, positive predictive value and negative predictive value of 81.8%, 96.6%, 85.7% and 95.5%, respectively.

CONCLUSIONS

An INC between the UEGM and the BEGM can predict the origin of PVCs arising from PSCs. An initial negative concordance between unipolar and bipolar electrograms indicates that the distal electrode of the ablation catheter is at the origin of premature ventricular contractions within pulmonary sinus cusps.

MANual vs. automatIC local activation time annotation for guiding Premature Ventricular Complex ablation procedures (MANIaC-PVC study)

AIMS

To assess potential benefits of a local activation time (LAT) automatic acquisition protocol using wavefront annotation plus an ECG pattern matching algorithm [automatic (AUT)-arm] during premature ventricular complex (PVC) ablation procedures.

METHODS AND RESULTS

Prospective, randomized, controlled, and international multicentre study (NCT03340922). One hundred consecutive patients with indication for PVC ablation were enrolled and randomized to AUT (n = 50) or manual (MAN, n = 50) annotation protocols using the CARTO3 navigation system. The primary endpoint was mapping success. Clinical success was defined as a PVC-burden reduction of ≥80% in the 24-h Holter within 6 months after the procedure. Mean age was 56 ± 14 years, 54% men. The mean baseline PVC burden was 25 ± 13%, and mean left ventricular ejection fraction (LVEF) 55 ± 11%. Baseline characteristics were similar between the groups. The most frequent PVC-site of origin were right ventricular outflow tract (41%), LV (25%), and left ventricular outflow tract (17%), without differences between groups. Radiofrequency (RF) time and number of RF applications were similar for both groups. Mapping and procedure times were significantly shorter in the AUT-arm (25.5 ± 14.3 vs. 32.8 ± 12.6 min, P = 0.009; and 54.8 ± 24.8 vs. 67.4 ± 25.2, P = 0.014, respectively), while more mapping points were acquired [136 (94-222) AUT vs. 79 (52-111) MAN; P < 0.001]. Mapping and clinical success were similar in both groups. There were no procedure-related complications.

CONCLUSION

The use of a complete automatic protocol for LAT annotation during PVC ablation procedures allows to achieve similar clinical endpoints with higher procedural efficiency when compared with conventional, manual annotation carried out by expert operators.

A new quantitative mapping criterion to localize the ablation target of right ventricular outflow tract arrhythmias

PURPOSE

(1) To explore the electrophysiological characteristics of the bipolar and unipolar electrogram (UEGM) of ablation targets for RVOT arrhythmias. (2) To optimize the diagnostic criteria of RVOT arrhythmia ablation targets.

METHODS AND RESULTS

A consecutive series of 111 patients with RVOT arrhythmias who underwent radiofrequency catheter ablation (RFCA) were studied. The voltage of bipolar potential for ablation targets were evaluated by three-dimensional voltage mapping procedure. The max slope of the descending limb (MSDL)、local activation preceding time (LAPT), the interval of the descending limb (IDL) and the interval of MSDL (IMSDL) of the unipolar potential were then calculated and analyzed for successful targets(ST) and failed targets(FT)groups. Successful ablation was achieved in 102 patients and 9 patients failed. LAPT was higher in the ST group than that in FT group (30.0 ± 4.3 ms vs 22.8 ± 6.3 ms, P < 0.001). IMSDL was lower in the ST group than that in FT group (9.93 ± 6.32 ms vs 21.7 ± 16.1 ms, P < 0.001). IMSDL and LAPT have a predictive value for a ST (AUC 75% and 83.7%). The optimal cut off value for LAPT and IMSDL were 24.5 ms and 20 ms respectively. A better predictive value can be acquired when IMSDL and LAPT were used in combination (AUC 93.9%, Sensibility/Specificity 92.3%/84.2%).

CONCLUSION

A combined use of LAPT and IMSDL may be helpful as an additional criterion for ST judgement.

[Premature ventricular contractions and tachycardia in a structurally normal heart : Idiopathic PVC and VT]

Premature ventricular contractions (PVC) are a common, often incidental and mostly benign finding. Treatment is indicated in frequent and symptomatic PVC or in cases of worsening of left ventricular function. Idiopathic ventricular tachycardia (VT) is mostly found in patients with a structurally healthy heart. These PVC/VT usually have a focal origin. The most likely mechanism is delayed post-depolarization. Localization of the origin is based on the creation of an activation map with or without combination of pace mapping. Idiopathic PVC/VT are most frequently located on the outflow tracts of the right and left ventricles, including the aortic root. Other typical locations include the annulus of the tricuspid or mitral valve, papillary muscles and Purkinje fibers. Catheter ablation is an alternative to antiarrhythmic medication in symptomatic monomorphic PVC/VT. The success rate is good whereby mapping and ablation can often represent a challenge. This article is the fifth part of a series dedicated to specific advanced training in the field of special rhythmology and invasive electrophysiology. It describes the pathophysiological principles, types and typical findings that can be obtained during an electrophysiological investigation.

Focal atrial tachycardia ablation: Highly successful with conventional mapping

BACKGROUND/OBJECTIVE

Radiofrequency catheter ablation (RFCA) of focal atrial tachycardia (FAT) traditionally is guided by conventional endocardial mapping of earliest atrial activation; however, more recently electro-anatomical mapping is heralded as a more effective, albeit more expensive, tool to guide ablation. Herein we present the results of conventional mapping-guided RFCA. Apropos, we conducted a literature search of studies reporting > 10 FAT patients submitted to RFCA.

METHODS AND RESULTS

Conventional mapping-guided RFCA, performed in 63 FAT patients (aged 42.4 + 17.3 years; 14 with incessant tachycardia and 12 with tachycardiomyopathy (TCM)), was successful in 61 (96.8%) patients, applied for single foci in 59 (93.7%) and two foci in 4 patients, right (n = 46) or left sided (n = 17). The earliest atrial activation time at the ablation site was 41.3 ± 16.2 ms. Fluoroscopy time averaged 27.3 + 18.7 min, and procedure lasted 2.6 + 1.7 h. Complications occurred in two patients (sinus pauses in one needing a pacemaker and a large inguinal hematoma in one). Over 29.0 + 22.9 months, four patients (6.5%) had recurrences, of whom three were successfully re-ablated. All patients with TCM showed gradual improvement to normalization over 4-6 months. Literature search showed that RFCA success is equally high when guided with either conventional (88.5%) or electro-anatomical mapping (90%) with similar recurrences (9.6% vs. 9.5%).

CONCLUSION

Conventional mapping-guided RFCA of FAT had high success (96.8%) with low complication (3.2%) and recurrence rates (6.5%). TCM was fully reversible. These results are comparable to those achieved with the more expensive electro-anatomical mapping, which may be reserved for more complex cases or for those failing the conventional approach.

In vivo human sock-mapping validation of a simple model that explains unipolar electrogram morphology in relation to conduction-repolarization dynamics

INTRODUCTION

The unipolar electrogram (UEG) provides local measures of cardiac activation and repolarization and is an important translational link between patient and laboratory. A simple theoretical model of the UEG was previously proposed and tested in silico.

METHOD AND RESULTS

The aim of this study was to use epicardial sock-mapping data to validate the simple model's predictions of unipolar electrogram morphology in the in vivo human heart. The simple model conceptualizes the UEG as the difference between a local cardiac action potential and a position-independent component representing remote activity, which is defined as the average of all action potentials. UEGs were recorded in 18 patients using a multielectrode sock containing 240 electrodes and activation (AT) and repolarization time (RT) were measured using standard definitions. For each cardiac site, a simulated local action potential was generated by adjusting a stylized action potential to fit AT and RT measured in vivo. The correlation coefficient (cc) measuring the morphological similarity between 13,637 recorded and simulated UEGs was cc  =  0.89 (0.72-0.95), median (Q₁ -Q₃ ), for the entire UEG, cc  =  0.90 (0.76-0.95) for QRS complexes, and cc  =  0.83 (0.58-0.92) for T-waves. QRS and T-wave areas from recorded and simulated UEGs showed cc> 0.89 and cc> 0.84, respectively, indicating good agreement between voltage isochrones maps. Simulated UEGs accurately reproduced the interaction between AT and QRS morphology and between RT and T-wave morphology observed in vivo.

CONCLUSIONS

Human in vivo whole heart data support the validity of the simple model, which provides a framework for improving the understanding of the UEG and its clinical utility.

Conventional mapping and ablation of focal ventricular tachycardias in the healthy heart

Ventricular tachycardias (VT) in the healthy heart, also known as idiopathic VTs, often have a focal origin. Triggered activity due to delayed after-depolarization is the most likely mechanism of focal VTs. Localization of the site of origin of focal VTs is based on activation mapping with or without combination with pace mapping. The characteristic anatomic site of origin of idiopathic VTs is the right and left outflow tract. Other sites include the tricuspid and mitral annulus, the papillary muscles, and Purkinje fibers. Catheter ablation is indicated for monomorphic symptomatic VT and can be an alternative to antiarrhythmic drugs. Success rates are high, but mapping and ablation can be challenging. We review the main electrophysiological findings and the important clues for ablation of focal VTs. Specific considerations for each location are considered.

Characterization of Electrograms from Multipolar Diagnostic Catheters during Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in USA with more than 2.3 million people affected annually. Catheter ablation procedure is a method for treatment of AF, which involves 3D electroanatomic mapping of the patient's left atrium (LA) by maneuvering a conventional multipolar diagnostic catheter (MPDC) along the LA endocardial surface after which pulmonary vein (PV) isolation is performed, thus eliminating the AF triggers originating from the PVs. However, it remains unclear how to effectively utilize the information provided by the MPDC to locate the AF-sustaining sites, known as sustained rotor-like activities (RotAs). In this study, we use computer modeling to investigate the variations in the characteristics of the MPDC electrograms, namely, total conduction delay (TCD) and average cycle length (CL), as the MPDC moves towards a RotA source. Subsequently, a study with a human subject was performed in order to verify the predictions of the simulation study. The conclusions from this study may be used to iteratively direct an MPDC towards RotA sources thus allowing the RotAs to be localized for customized and improved AF ablation.

Non-pharmacological management of ventricular tachycardia

Ventricular tachyarrhythmias (VTA), a major cause of sudden cardiac death, require meticulous management in order to prevent recurrent episodes. Recently, non-pharmacological interventions, including radiofrequency catheter ablation and implantable cardioverter defibrillators (ICD), have become important treatments of VTA. Catheter ablation is curative in a relatively high percentage of patients presenting with idiopathic monomorphic ventricular tachycardia (VT). For VT associated with structural heart disease, however, the efficacy of catheter ablation remains limited, and ICD is the first-line therapy. In a subset of patients presenting with recurrent episodes of ventricular fibrillation (VF), catheter ablation is a therapeutic option when the VF is triggered by specific premature ventricular complexes. In Japan, unlike in the United States and Europe, ICD have not yet been accepted as first-line prevention of sudden cardiac death caused by VTA. The efficacy of ICD is occasionally limited by intolerable complications, such as electrical storm, inappropriate shock delivery and infection. Catheter ablation and ICD therapy might need to be combined for problematic cases.

Atrial Unipolar Potential in Radiofrequency Catheter Ablation of Atrial Tachycardia

We conducted this study to verify the efficacy of atrial unipolar potentialfor for ablation of atrial tachycardia. The morphology of atrial unipolar potential at the successful and the best unsuccessful ablation sites was analyzed in 35 patients with atrial tachycardia (sino-atrial reentrant tachycardia (SART) 15, adenosine-sensitive atrial reentrant tachycardia near the His bundle (HAT) 10, and non-reentrant ectopic atrial tachycardia (EAT) 10). The usefulness of atrial unipolar potential was compared with the Ao-Po interval. The incidences of QS pattern at the successful and the best unsuccessful sites were (successful versus unsuccessful; P, respectively) 93 versus 55%; P = 0.20 in SART, 90 versus 0%; P = 0.0001 in HAT, and 90 versus 10%; P = 0.001 in EAT. The mean Ao-Po intervals at the successful and the best unsuccessful sites were 35 versus 30 ms; NS in SART, 48 versus 45 ms; NS in HAT, and 58 versus 50 ms; NS in EAT. A significantly higher incidence of transient success at QS pattern sites was observed in SART than in HAT or EAT (n = 2 +/- 0.8 versus 0.2 +/- 0.1 and 0.1 +/- 0.1, P = 0.0005), and each transient site and final success site in SART was distributed linearly. The sensitivity and specificity of QS patterns with regard to the determination of appropriate target sites were 0.91 and 0.45 in SART, 0.9 and 1.0 in HAT, and 0.88 and 0.88 in EAT, respectively. In ablation of HAT and EAT, the QS pattern is very useful and should be given high priority when determining the optimum target site. In SART, the ablation success was often achieved by multiple, linear RF delivery near perinodal tissue, and the QS pattern could be a candidate for the optimum target site.

Recording Techniques for Clinical Electrophysiology

The precise techniques employed in the electrophysiology laboratory influence the nature of the electrograms that are recorded during mapping procedures. Unipolar recordings that are minimally filtered can be useful for mapping focal arrhythmia sources, but have substantial far-field signal that can obscure low-amplitude signals of interest in abnormal regions. Bipolar recordings are standard in most laboratories because rejection of far-field signal facilitates identification of local potentials in abnormal areas, but the signal of interest can be beneath either recording electrode and far-field signals do occur. Simultaneously obtained unipolar recordings are a useful adjunct to bipolar recordings in some situations. High pass filtering and digital sampling also influence electrogram characteristics. High pass filtering of unipolar recordings can be useful to reduce far-field components, but limits inferences from electrogram morphology.

Influence of High-Pass Filtering on Noncontact Mapping and Ablation of Atrial Tachycardias

The aim of the study was to define the impact of different high-pass filter settings (HPF) on the accuracy of mapping of ectopic atrial tachycardias (EAT) using a noncontact mapping (NCM) system. In 20 patients with 22 EAT a noncontact probe was deployed in the right (n = 19) or in the left atrium (n = 3). The device enables interpolation and analysis of unipolar electrograms. It provides information on focus localization and signal morphology. These parameters were compared in different HPF of 0.5 Hz, 2 Hz, 8 Hz, and 16 Hz. The NCM signal morphology was preserved at all HPF. An initial negative deflection recorded by NCM system showed a positive predictive value of 93% regarding the ablation success. The deviation (spatial disparity) between visualized focus origin and successful ablation site was 6.9 +/- 5.4 mm. Between two consecutive filter settings, the focus shift was more pronounced between 0.5 and 2 Hz (5.4 +/- 4.5 mm) compared to a setting between 8 and 16 Hz (2.9 +/- 2.9 mm; P < 0.05). Successful ablation was achieved in 15/18 right atrial tachycardias (83%) and in 2/3 left atrial arrhythmias. Different HPF influence NCM spatial analysis of EAT. However, a small variability in foci localization does not impact final ablation results.