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.

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.

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.

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.

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.

Reduced fluoroscopy exposure during ablation of atrial fibrillation using a novel electroanatomical navigation system: a multicentre experience.

AIMS: Catheter ablation of atrial fibrillation (AF) focuses on pulmonary vein (PV) ablation with or without additional atrial substrate modification. These procedures require significant fluoroscopy exposure. A new 3D non-fluoroscopic navigation system (CARTO(®) 3 System, Biosense Webster, CA, USA) that allows precise location visualization of diagnostic and ablation catheters was evaluated for its impact on fluoroscopic exposure during AF ablation procedures. METHODS AND RESULTS: Two groups of patients were treated by our centres for drug refractory AF. One group was treated using the new CARTO(®) 3 system to guide catheter ablation (Group A, 117 patients). The other group was treated using the CARTO(®) XP system (Biosense Webster) 3 months previously (Group B, 123 patients). For both groups, circumferential PV ostia ablation was performed; PV isolation was validated using a circular catheter placed at each ostium. There was no difference in any clinical characteristics (age, sex, AF type, left atrium diameter and volume, and heart disease) among the two study groups. The mean number of PVs identified and isolated per patient was similar in both groups, as were the mean procedural duration and radiofrequency time. However, mean fluoroscopic time was significantly reduced in Group A (15.9±12.3 min) as compared with Group B (26±15.1 min) (P < 0.001). CONCLUSION: This multicentre observational study demonstrates a significant reduction of fluoroscopy exposure using a new 3D non-fluoroscopic mapping system to guide AF catheter ablation.

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.

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.

Atrial tachycardias in patients with congenital heart disease: a minimally invasive simplified approach in the use of three-dimensional electroanatomic mapping.

AIMS: Atrial tachycardia (AT) is a common complication after repair of congenital heart disease (CHD). This two-centre prospective study evaluated the ability of three-dimensional electroanatomic mapping (EAM) to guide ablation of ATs in this particular population with a minimally invasive simplified approach. METHODS AND RESULTS: Thirty-one consecutive patients (mean age 26 ± 17 years) with AT after repair of CHD were treated with a very limited number of intracavitary catheters and a specific setting of the Window of Interest (WoI) for the ablation of post-surgical ATs. A single-intracavitary catheter approach was performed in 22 patients, whereas an overall use of two intracavitary catheters in the other nine patients. Thirty-one patients exhibited 41 ATs. Seventy-six per cent of these were macro-reentrant ATs (MRATs), and 24% were focal ATs (FAT). The mid-diastolic isthmus (MDI) was located in the right atrial free wall (RAFW) in 82.8% of MRATs. Also in FATs, the RAFW was the most common site (77.8%) of the ectopic focus. Fifty-eight per cent of MRATs showed a double-loop reentry, with both loops sharing the same MDI in all cases. In 87% of cases, the abolition of the MRAT was obtained by applying radiofrequency energy to the MDI. Ninety per cent of FATs were successfully ablated. Mean conduction velocity and voltage amplitude had significantly lower values in successfully treated than in unsuccessfully treated MRATs. CONCLUSION: Three-dimensional EAM, performed with a minimally invasive simplified approach and by using a specific parameter setting of the WoI, showed to be very effective to guide ablation of ATs in CHD patients.

Electroanatomic mapping and ablation of macroreentrant atrial tachycardia: comparison between successfully and unsuccessfully treated cases.

INTRODUCTION: Ablation of macroreentrant atrial tachycardia (MRAT) is demanding and identification of predictors of failure may be of help in patient management. This study compares the characteristics of successfully versus unsuccessfully treated patients undergoing electroanatomic mapping (EAM) and ablation of MRAT. METHODS AND RESULTS: Consecutive patients undergoing EAM and ablation of MRAT were included. Ablation was linearly placed at the mid-diastolic isthmus (MDI) to achieve arrhythmia interruption and conduction block. Variables were analyzed for predictors of both procedural failure and cumulative failure (procedural failure + early recurrences). Fifty-two patients (37 M; age 64 +/- 16 years) with 56 MRATs were considered. The MRAT was in the right atrium in 25 morphologies (45%) and 32 (57%) showed a double-loop reentry. Fifty-one morphologies (91%) in 47 patients were successfully treated; 3 patients had early recurrences of the same MRAT. None of the clinical variables considered significantly differed in the successfully treated group as compared to the unsuccessfully treated. Conversely, there was a significant difference as to the EAM characteristics: successfully treated cases showed a narrower target isthmus with a lower voltage amplitude and slower conduction velocity (CV). In the MDI, a CV >60 cm/sec and a width >40 mm were the strongest predictors of procedural failure and cumulative failure, respectively. CONCLUSIONS: In this patient population, while the clinical variables did not differ significantly, there was a significant difference in the EAM characteristics between successfully and unsuccessfully treated cases. CV and width of the isthmus target for ablation were the strongest independent predictors of procedure outcome.

Use of a novel sharp-tip, J-shaped guidewire to facilitate transseptal catheterization.

AIMS: Transseptal catheterization (TSP-C) is a demanding procedure and at the same time one of the key points of atrial fibrillation ablation, an increasingly diffused procedure. This study prospectively evaluates the usefulness of a novel sharp-tip, J-shaped 0.014'' transseptal guidewire (TSP-GW) to facilitate TSP-C in case of resistant atrial septum (AS). METHODS AND RESULTS: Consecutive patients undergoing TSP-C for arrhythmia ablation in a single centre were considered for the study. TSP-C was performed according to a standardized technique. The criterion to use the TSP-GW was a resistant AS, defined as inability to perforate the fossa ovalis by applying moderate pressure to a standard Brockenbrough needle. The TSP-GW was inserted in the needle lumen and advanced to puncture the AS and enter the left atrium; subsequently, the transseptal assembly was advanced over the TSP-GW. Double transseptal puncture was routinely performed for ablation of atrial fibrillation. Eighty-one patients (54 males, 27 females; mean age 54 +/- 17 years, range 12-81) undergoing TSP-C were enrolled; 132 TSP-C procedures were planned and accomplished. Nineteen patients (23%) in 27 procedures showed a resistant AS. In all these procedures, the TSP-GW was safely and successfully used to accomplish the TSP-C. In patients with a resistant AS, only a significantly lower prevalence of structural heart disease was observed when compared with controls. No complication related to TSP-C was observed. CONCLUSION: The TSP-GW facilitates TSP-C in 23% of the patients, in whom a resistant AS is encountered. In this population, there was no clinical predictor of such anatomy.

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.

[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.