Cryoablation of para-Hisian and mid-septal accessory pathways: long-term outcomes of a specific stepwise cryoablation protocol.

BACKGROUND: Although cryoablation (CA) of septally located accessory pathways (APs) is an established treatment for Wolff-Parkinson-White Syndrome, its major limitation is the lack of data regarding long-term follow-up (FU). The present study sought to investigate long-term outcomes of a specific CA protocol targeting para-Hisian (P-H) and mid-septal (M-S) APs. METHODS: Twenty-six patients who previously underwent CA of PH or MS APs from 2004 to 2014, were prospectively considered to receive a FU during 2021. All subjects received an outpatient control visit, performing an exercise stress test and a 24-h ECG Holter monitoring. RESULTS: Acute success was achieved in 22 patients (85%). One case of recurrence was reported at short-term FU. Long-term FU, performed after a mean time of 150±37 months, did not show ventricular preexcitation recurrences, with a success rate of 81%, and without late adverse events. Symptoms reduction (12% vs. 96%, P<.001) and lower rates of antiarrhythmic drug use (12% vs. 62%, P<.001) were observed at long term-FU with respect to baseline. This clinical outcome was detected also among patients who underwent unsuccessful CA at baseline. CONCLUSIONS: Our CA protocol confirmed remarkable safety and efficacy throughout a long-term FU. Significant clinical improvement in terms of antiarrhythmic therapy discontinuation and symptoms reduction was also shown among patients who experienced acute failure of CA.

Pathophysiology of Atypical Atrial Flutters.

Atypical atrial flutters are complex supraventricular arrhythmias that share different pathophysiological aspects in common. In most cases, the arrhythmogenic substrate is essentially embodied by slow-conducting areas eliciting re-entrant circuits. Although atrial scarring seems to promote slow conduction, these arrhythmias may occur even in the absence of structural heart disease. To set out the ablation strategy in this setting, three-dimensional mapping systems have proved invaluable over the last decades, helping the cardiac electrophysiologist understand the electrophysiological complexity of these circuits and easily identify critical areas amenable to effective catheter ablation.

Mapping and Ablation of Atypical Atrial Flutters.

Atypical atrial flutters are complex, hard-to-manage atrial arrhythmias. Catheter ablation has progressively emerged as a successful treatment option with a remarkable role played by irrigated-tip catheters and 3D electroanatomic mapping systems. However, despite the improvement of these technologies, the ablation results may be still suboptimal due to the progressive atrial substrate modification occurring in diseased hearts. Hence, a patient-tailored approach is required to improve the long-term success rate in this scenario, aiming at achieving specific procedure end points and detecting any potential arrhythmogenic substrate in each patient.

Atypical Cases of Typical Atrial Flutter? A Case Study.

Ablation of typical atrial flutter has a high safety and efficacy profile, but hidden pitfalls may be encountered. In some cases, a longer cycle length with isoelectric lines is associated with a different or more complex arrhythmogenic substrate, which may be missed if conduction block of the cavotricuspid isthmus is performed in the absence of the clinical arrhythmia. Prior surgery may have consistently modified the atrial substrate and complex or multiple arrhythmias associated with an isthmus-dependent circuit can be encountered. In these cases, electroanatomic mapping is useful to guide the procedure and plan an appropriate ablation strategy.

Procedural Feasibility and Long-Term Efficacy of Catheter Ablation of Atypical Atrial Flutters in a Wide Spectrum of Heart Diseases: An Updated Clinical Overview.

Atypical atrial flutters (AAFL) are difficult-to-manage atrial arrhythmias, yet potentially amenable to effective radiofrequency catheter ablation (CA). However, data on CA feasibility are only sparingly reported in the literature in different clinical settings, such as AAFL related to surgical correction of congenital heart disease. The aim of this review was to provide an overview of the clinical settings in which AAFL may occur to help the cardiac electrophysiologist in the prediction of the tachycardia circuit location before CA. Moreover, the role and proper implementation of cutting-edge technologies in this setting were investigated as well as which procedural and clinical factors are associated with long-term failure to maintain sinus rhythm (SR) to find out which patients may, or may not, benefit from this procedure. Not only different surgical and non-surgical scenarios are associated with peculiar anatomical location of AAFL, but we also found that CA of AAFL is generally feasible. The success rate may be as low as 50% in surgically corrected congenital heart disease (CHD) patients but up to about 90% on average after pulmonary vein isolation (PVI) or in patients without structural heart disease. Over the years, the progressive implementation of three-dimensional mapping systems and high-density mapping tools has also proved helpful for ablation of these macro-reentrant circuits. However, the long-term maintenance of SR may still be suboptimal due to the progressive electroanatomic atrial remodeling occurring after cardiac surgery or other interventional procedures, thus limiting the likelihood of successful ablation in specific clinical settings.

Arrhythmias Involving Variants of Accessory Pathways.

In some cases, atrioventricular reentrant arrhythmias are sustained by accessory pathways with peculiar electrophysiologic properties related to their specific anatomy. Most of these fibers, which may be responsible for variants of ventricular preexcitation, show decremental conduction properties due to a nodelike aspect or a peculiar tortuous anatomic route across the atrioventricular groove. Moreover, some fibers do not actively sustain any reentrant circuit and can be only involved as bystander in other arrhythmias. Although rare, these accessory pathway variants should be properly diagnosed using noninvasive and invasive methods to guide catheter ablation procedures when needed.

Ablation of Accessory Pathways with Challenging Anatomy.

Although catheter ablation of accessory pathways is deemed highly safe and effective, peculiar location of these pathways might lead to complex and potentially hazardous procedures requiring ablation in anatomic regions such as para-Hisian area, coronary sinus, and epicardial surface. The electrophysiologist should know these possible scenarios to plan the best strategy for safe and effective ablation of these uncommon accessory pathways.

Challenges in Narrow QRS Complex Tachycardia Interpretation.

Several arrhythmogenic substrates may generate narrow QRS complex tachycardia, frequently encountered in clinical practice. Some narrow QRS complex tachycardias, however, are sustained by an uncommon arrhythmogenic mechanism. Although rare, these forms should be taken into account in the differential diagnosis to avoid misdiagnosis and improper patient management. Dual atrioventricular node physiology can be responsible for different uncommon forms of narrow QRS complex tachycardia, also nonreentrant in mechanism. A ventricular origin also is possible, if the tachycardia site is located in the upper ventricular septum with fast ventricular propagation to the specific conduction system and narrowing of the QRS complex.

Efficacy and safety of cryoablation of para-Hisian and mid-septal accessory pathways using a specific protocol: single-center experience in consecutive patients.

PURPOSE: Radiofrequency (RF) catheter ablation of para-Hisian (P-H) and mid-septal (M-S) accessory pathways (APs) is a potentially harmful procedure due to their close location to the A-V node. Conversely, cryoablation (CA) appears safer in this setting. The aim of this study was to assess the efficacy and safety of CA of these APs using a specific protocol. METHODS: Fifty-three patients undergoing CA for P-H (45) or M-S (8) APs were included. CA was performed with a 4-mm catheter at - 75 °C for 480 s in the site where conduction block over the AP was obtained by a specific cryomapping protocol. Optimal catheter-tissue contact was achieved by inferior or superior vena cava approach. In case of failure, a 6-mm catheter and/or trans-septal catheterization (TSC) were considered. Normal AV conduction was monitored throughout CA, which was interrupted in case of its inadvertent modifications. RESULTS: In 46 patients (87%), CA was successful. Reasons for failure were as follows: lack of AP interruption (3 patients), intraprocedure AP conduction resumption (3), or transient A-H interval prolongation (1). Failure was associated with more aggressive approach including multiple procedures, greater use of 6-mm catheters, TSC, and longer CA applications. No major complications were observed. Three out of 46 patients (6.5%) experienced relapse of AP conduction during follow-up and were successfully re-treated by CA. CONCLUSIONS: CA of P-H and M-S APs is highly safe and effective and a specific protocol for cryomapping and CA could lead to a low recurrence rate at follow-up.

Development of simulation combining a physical heart model and three-dimensional system for electrophysiology training.

BACKGROUND: A new three-dimensional heart anatomical simulator (3D HAS) has been created combining a physical heart model with an electroanatomic mapping (EAM) system. The aim of this study is to describe the development and the validation process of this device. METHODS: We developed the 3D HAS combining a physical heart model with an EAM system. This simulator was then validated by 10 electrophysiologists, subdivided in two groups based on their experience in electrophysiology procedures. The performance of the experts was compared to the one of the novices in achieving three different tasks: fluoroless reconstruction of the right atrium, coronary sinus cannulation, and deployment of a linear ablation lesion in the cavotricuspid isthmus. For each operator, a score was calculated based on objective parameter for each task and for the overall performance. RESULTS: The 3D HAS was located in an environment that allowed use of the main features of the EAM system including contact force sensing. No technical issue was encountered during the validation process. The experts' performance was significantly better than the one of the novices both overall (P = 0.009) and in each task (right atrium reconstruction, P = 0.016; coronary sinus cannulation, P = 0.008; ablation lesion, P = 0.03). CONCLUSIONS: The 3D HAS is reliable and allows use of the main features of an EAM system in the right atrium. The ability to discriminate different levels of experience suggests that this simulator is enough realistic and could be useful for electrophysiology training.

[Asymptomatic ventricular pre-excitation: what management?] / Pre-eccitazione ventricolare in assenza di sintomi: che strada percorrere?

The management of asymptomatic patients with ventricular pre-excitation diagnosed occasionally is controversial. In fact, the lack of clinical arrhythmias does not necessarily define a benign condition: it could be possibly due to poor conduction over the accessory pathway or, conversely, to peculiar and individual conditions, which, even if the accessory pathway is capable of fast conduction, can prevent the onset of arrhythmias. These can occur unexpectedly during follow-up and may include malignant ventricular arrhythmias, although sudden death is very rare in this clinical scenario. An aggressive strategy aiming at extensive ablation in all cases with asymptomatic ventricular pre-excitation is not justified, as well as the "wait-and-see" approach. Clinically, it is important to accurately define the individual risk of any arrhythmia related to the accessory pathway, which may require treatment. For decades, the management of asymptomatic ventricular pre-excitation has been quite inhomogeneous among centers and in some cases it is still very different. Recently, a consensus document proposed the combined use of non-invasive and invasive diagnostic tools for accurate screening of these patients. If non-invasive methodologies are unable to demonstrate poor conduction over the accessory pathway, then an invasive approach is justified for arrhythmia risk definition and, if necessary, adequate therapy.

Optimization of catheter/tissue contact during pulmonary vein isolation: the impact of atrial rhythm.

Aims: During pulmonary vein isolation (PVI), even if operators are aware of the contact force (CF), its values may greatly vary and the impact of cardiac rhythm has not been thoroughly investigated yet. This study aims at assessing the actual values of CF, the applications with suboptimal CF, and the impact of cardiac rhythm on CF during PVI. Methods and results: Twenty patients undergoing point-by-point PVI with a CF-sensing catheter were considered. CF target was between 6 and 40 g. The mean CF per application (mCF) was evaluated and considered suboptimal if ≤5 g. The real-time graphic of CF was also evaluated and classified as pulsatile if regular variations synchronous with the atrial rate were seen; otherwise it was irregular. To achieve PVI, 1458 applications were delivered; 287 (19.68%) had suboptimal mCF. A great variability of mCF was seen according to anatomy, operators and patients. Compared to applications in atrial fibrillation (AF), those in sinus rhythm (SR) showed a higher median value of mCF (11 vs. 9 g; P = 0.0099) and a lower percentage of suboptimal mCF (17.95% vs. 25.15%; P = 0.0051). Compared to the irregular, the pulsatile pattern, almost exclusively observed in SR, was associated with higher mCF (14.69 ± 8.77 vs. 10.79 ± 7.89 g; P < 0.0001) and fewer suboptimal applications (8.02% vs. 27.73%; P < 0.0001). Conclusion: During PVI, several factors influence CF, which, despite optimization attempts, can be suboptimal in ∼20% of the applications. However, CF is higher in SR than in AF and this is strictly associated with a pulsatile pattern of instant CF values.

The effects of gender on electrical therapies for the heart: procedural considerations, results and complications: A report from the XII Congress of the Italian Association on Arrhythmology and Cardiostimulation (AIAC).

Use of cardiac implantable devices and catheter ablation is steadily increasing in Western countries following the positive results of clinical trials. Despite the advances in scientific knowledge, tools development, and techniques improvement we still have some grey area in the field of electrical therapies for the heart. In particular, several reports highlighted differences both in medical behaviour and procedural outcomes between female and male candidates. Women are referred later for catheter ablation of supraventricular arrhythmias, especially atrial fibrillation, leading to suboptimal results. On the opposite females present greater response to cardiac resynchronization, while the benefit of implantable defibrillator in primary prevention seems to be less pronounced. Differences on aetiology, clinical profile, and development of myocardial scarring are the more plausible causes. This review will discuss all these aspects together with gender-related differences in terms of acute/late complications. We will also provide useful hints on plausible mechanisms and practical procedural aspects.

Left atrial appendage thrombi relate to easily accessible clinical parameters in patients undergoing atrial fibrillation transcatheter ablation: A multicenter study.

BACKGROUND: Transesophageal echocardiography (TEE) is routinely performed before atrial fibrillation (AF) transcatheter ablation to exclude the presence of left atrial (LA) or LA appendage (LAA) thrombi. The aim of the study is to evaluate if easily accessible clinical parameters may relate to the presence of LA or LAA thrombi to identify patients who could potentially avoid TEE. METHODS AND RESULTS: Between January 2012 and September 2014, data from 1539 consecutive patients undergoing TEE, as a work-up before AF transcatheter ablation, in six large volume centers were collected. Baseline clinical features, CHA2DS2-VASc score, transthoracic echocardiography and presence of thrombi at TEE were recorded. Exclusion criteria were valvular, hypertrophic or dilated cardiomyopathy, previous heart surgery or an ejection fraction ≤35%. Mean age was 59.6±10.4years, 1215 (78.9%) were males; 951 (62.9%) presented in sinus rhythm (SR) on admission, 324 (21.1%) had undergone at least one previous ablation and 900 (58.5%) had CHA2DS2-VASc score 0-1. Thrombi were encountered in 12 patients (0.8%). SR at TEE independently related to the absence of thrombi (OR 5.15, 95% CI 1.38-19.02, p=0.015); in addition to this, no patient with a CHA2DS2-VASc score 0-1 and SR on admission presented thrombi at TEE (specificity 100%, p=0.011). CONCLUSION: In a selected population of patients referred for AF ablation, LA/LAA thrombi prevalence is low. No patients in SR with CHA2DS2-VASc score 0-1 presented LAA thrombi at TEE, identifying a significant subset of patients who could potentially safely be spared from pre-procedural TEE.

Validation of a High-Fidelity Electrophysiology Simulator and Development of a Proficiency-Based Simulator Training Program.

INTRODUCTION: Simulator training can potentially provide high-intensity training in electrophysiology (EP) without compromising patient safety. We assessed the construct validity of a novel EP simulator (ANGIO Mentor; Simbionix) and developed proficiency-based scores for clinical EP simulator training. METHODS: Two European training centers participated. Participants were grouped on the basis of years of EP experience and (for a subset) subjectively scored clinical catheter manipulation skills. Each participant attempted the simulator's 5 modules 3 times. These modules focus on catheter manipulation in 3-dimensional models, ranging from geometric shapes to fluoroscopic contracting cardiac models, with performance scored by the system on the basis of attainment of preset targets. Using these scores, targets were formulated for basic EP training. RESULTS: Twenty-eight participants were included (13 with subjectively scored catheter manipulation). Scores for participants with less than 1-year EP experience (group 1) were significantly lower for each of the attempts at the modules (P < 0.002). For group 1 only, scores improved with subsequent attempts (P < 0.005). In 4 of the 5 modules, scores of group 1 were significantly lower than the more experienced groups (P < 0.0005). Participants with subjectively scored above-average catheter manipulation skills also had higher scores in 4 of the 5 modules (P < 0.05). Target scores for a proficiency-based training program were generated from the median scores for each module for those with 1-year experience or more. CONCLUSIONS: Scores attained in the simulator can distinguish those with less than 1-year EP experience and those with above-average catheter manipulation skills. Consequently, target scores have been generated for a proficiency-based training program.

Agenesia of the left atrial appendage: possible but very rare.

: Agenesia of the left atrial appendage in a patient with atrial fibrillation is shown. Although of interest, the prevalence of this abnormality is very low.

Invasive electrophysiological evaluation and ablation in patients with asymptomatic ventricular pre-excitation persistent at exercise stress test.

AIMS: In patients with asymptomatic ventricular pre-excitation (VPE) persistent at exercise stress test, this study evaluates the proportion of cases with adverse conduction properties of the atrioventricular accessory pathway (AP) at invasive electrophysiological study and the long-term follow-up after they received treatment according to pre-determined criteria. METHODS AND RESULTS: Over 10 years, asymptomatic patients with VPE persistent at exercise stress test referred for invasive electrophysiological evaluation including isoproterenol (IPN) infusion were included. Ablation was planned if they had at least one of the following criteria: (i) shortest pre-excited R-R interval (SPERRI) ≤250 ms and/or (ii) inducible atrioventricular re-entrant tachycardia (AVRT). Cryoablation was electively used in para-hisian and mid-septal APs. Patients non-eligible for ablation received no therapy. Sixty-three patients (45 males; mean age 26 ± 14 years) underwent electrophysiological evaluation: 7 had fasciculo-ventricular fibres and were excluded, whereas 56 had 58 APs. Thirty-one patients (55%) were eligible and underwent successful ablation: 87% had at least the SPERRI ≤ 250 ms and 61% had at least inducible AVRT. In 15 cases (48%) the ablation criteria were met only during IPN infusion. During follow-up (73 ± 33 months), one patient was successfully retreated for resumption of VPE in the ablation group, whereas no event was observed in the group of patients who received no treatment. CONCLUSION: In this subset of patients with asymptomatic VPE, invasive electrophysiological evaluation shows fast antegrade conduction over the AP and/or inducible AVRT in about half of the cases. Patients who received no therapy because of a benign electrophysiological profile had an event-free follow-up.

Left atrial diverticula in patients undergoing atrial fibrillation ablation: morphologic analysis and clinical impact.

INTRODUCTION: Left atrial diverticula (LAD) have been reported to be (1) at risk for intracavitary thrombosis and cardiac perforation during ablation and (2) sites of extrapulmonary vein foci. In atrial fibrillation (AF) ablation, their presence might undermine procedure safety and efficacy. This observational study evaluates the morphology and clinical impact of LAD in patients undergoing AF ablation. METHODS AND RESULTS: Consecutive patients undergoing computed tomography scan (Aquilion 64, Toshiba, Otawara, Japan) and AF ablation with imaging integration (CARTO 3 Merge, Biosense Webster, CA, USA) in our center were included. Morphologic analysis was performed by 2 independent radiologists. Ablation was obtained by irrigated radiofrequency energy (Navistar Thermocool or Thermocool SF, Biosense Webster). Out of 212 patients, 58 (27.3%) had LAD; 74.4% of LAD were located in the anterosuperomedial left atrium. In patients with and without LAD, the prevalence of prior cerebrovascular events was similarly low. The rate of major periprocedure complications did not differ significantly: 1.7% versus 2.6% (P = 1) in patients with and without LAD, respectively. However, 1 case of cardiac perforation occurred during ablation in a diverticulum. During follow-up, survival free from arrhythmia recurrences was comparable in the 2 groups. CONCLUSION: LAD are present in about one-fourth of patients undergoing AF ablation and, in general, they have no impact on its safety and efficacy. However, occasionally, radiofrequency energy delivery in a LAD can cause tissue overheating and perforation.

Simulator training reduces radiation exposure and improves trainees' performance in placing electrophysiologic catheters during patient-based procedures.

BACKGROUND: Currently, training in interventional electrophysiology is based on conventional methodologies, and a paucity of data on the usefulness of simulation in this field is available. OBJECTIVE: The purpose of this study was to evaluate the impact of simulator training on trainees' performance in electrophysiologic catheter placement during the early phase of their learning curve. METHODS: Inexperienced electrophysiology fellows were considered. A hybrid high-fidelity simulator (Procedicus VIST, version 7.0, Mentice AB Gothenburg, Sweden for Biosense Webster) was used. The following parameters were evaluated in 3 consecutive patient-based procedures before and after two training sessions of at least 1.5 hours on the simulator: (1) ability to place catheters in conventional recording/pacing sites (coronary sinus, His-bundle area, high right atrium, and right ventricular apex); (2) amount of help provided by the supervisor (scale from 1-3; 3 for maximal help); (3) fluoroscopy time; and (4) positioning time. RESULTS: Seven fellows performed 168 catheter placements during 42 patient-based procedures with no complications. Comparing parameters before and after simulator training, there was a significant reduction in the mean amount of help and in fluoroscopy and positioning times per placement: from 1.71 ± 1.24 to 0.42 ± 0.68 (P <.001), from 121 ± 88 seconds to 76 ± 54 seconds (P <.001), and from 175 ± 138 seconds to 102 ± 74 seconds (P <.001), respectively. Overall fluoroscopy time per patient decreased from 567 ± 220 seconds to 305 ± 111 seconds (P <.0001). Improvement appeared to be related to simulator training alone and not to the previously performed patient-based procedures. CONCLUSION: During the early phase of the trainees' learning curve, simulator training significantly improves the independent trainees' performance with reduction in radiation exposure.