Electrophysiology Catheter Research Articles

High-Performance Continuous Hydraulic Motor for MR Safe Robotic Teleoperation

Magnetic resonance imaging (MRI) guided intervention has drawn increasing attention over the last decade. It is accredited to the capability of monitoring any physiological change of soft tissue with the high-contrast MR images. This also gives rise to the demand for precise tele-manipulation of interventional instruments. However, there is still lack of choices of MR safe actuators that provide high-fidelity robot manipulation. In this letter, we present a three-cylinder hydraulic motor using rolling-diaphragm-sealed cylinders, which can provide continuous bidirectional rotation with unlimited range. Both kinematics and dynamics models of the presented motor were studied, which facilitate its overall design optimization and position/torque control. Motor performance, such as step response, frequency response, and accuracy, were experimentally evaluated. We also integrate the motor into our catheter robot prototype designed for intra-operative MRI-guided cardiac electrophysiology (EP), which can provide full degree-of-freedom and precise manipulation of a standard EP catheter.

SEVEN TYPES OF PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA IN ONE PATIENT

The report describes the case of electrophysiological study and catheter ablation of seven types of supraventricular tachycardia in one patient. During radiofrequency ablation for WPW-syndrome three functionated discrete retrograde conductive accessory atrioventricular pathways were documented and were successfully ablated. Further incessant activity of two ectopic atrial focuses was revealed. First localized in upper part of crista terminalis and another – in left superior pulmonary vein ostium. Five months after patient had a recurrence of supraventricular tachycardia. EPI-study demonstrated evidence for retrograde ventriculoatrial dissociation with induction of atypical fast/slow and typical slow/fast atrioventricular nodal reentry tachycardia, wich were successfully ablated. With further observation, rhythm disturbances did not recur.

META-ANALYSIS OF ULTRASOUND-GUIDED VERSUS CONVENTIONAL VASCULAR ACCESS FOR ELECTROPHYSIOLOGY PROCEDURES AND CATHETER ABLATION

Vascular complications are important and common adverse events during electrophysiology studies and catheter ablation of arrhythmias, particularly with uninterrupted anticoagulation. There has been a shift towards ultrasound guidance for vascular access to reduce such complications, seen in some

Catheter ablation of supraventricular tachycardia in patients with dextrocardia and situs inversus.

Dextrocardia with situs inversus is a rare cardiac positional anomaly. Catheter ablation procedures performed in this set of patients have not been sufficiently reported. A total of 10 patients with dextrocardia and situs inversus who received catheter ablation for supraventricular tachycardia (SVT) were included from a cohort of over 20 000 cases of catheter ablation for SVT in three centers from 2005 to 2016. All patients underwent electrophysiologic study and catheter ablation of SVT. Ablation targets were selected based on different tachycardia mechanisms with the primary endpoint of noninduction of tachycardia. The average age was 32.4 ± 5.6 years. Congenitally corrected transposition of great arteries (TGA) with situs inversus and D-looping of the ventricles and aorta (congenitally corrected TGA {I,D,D}) was found in four patients, while the other six patients exhibited mirror-image dextrocardia {I,L,L}. The mechanisms of SVT were atrioventricular nodal reentrant tachycardia in four patients, atrioventricular reentrant tachycardia in three, typical atrial flutter in one, intra-atrial reentrant tachycardia in one, and focal atrial tachycardia in one. Immediate procedural success was achieved in 9 out of 10 patients with no procedural complications. During a follow-up period of 6.3 ± 3.5 years on average, all patients remained free from recurrent tachycardia. For patients with dextrocardia and situs inversus, catheter ablation of SVT is safe and feasible. Differences in catheter maneuver and fluroscopy projection, along with difficulties in distorted anatomy are major obstacles for successful ablation.

Electrophysiological properties of asymptomatic children and adolescents with the Wolff-Parkinson-White electrocardiographic pattern

Optimal management in asymptomatic children and adolescents with the Wolff-Parkinson-White (WPW) electrocardiographic pattern is still debatable. The aim of this retrospective study was to evaluate the electrophysiological properties of asymptomatic children and adolescents with WPW. The medical records and procedural data of asymptomatic children and adolescents with the WPW electrocardiographic pattern who underwent invasive electrophysiological study (EPS) and catheter ablation between April 2012 and April 2018 were evaluated. In all, 149 consecutive, asymptomatic children and adolescents with WPW who underwent EPS were retrospectively investigated. In 39 (26.2%) of the patients, a shortest pre-excited R-R interval of ≤250 ms during atrial fibrillation or an accessory pathway effective refractory period of ≤270 ms was found. A total of 39 patients with high-risk antegrade conduction and 45 patients with inducible orthodromic atrioventricular re-entrant tachycardia underwent catheter ablation. In addition, 14 patients underwent catheter ablation due to family preference. High-risk antegrade conduction properties are exhibited by more than one-quarter of asymptomatic children and adolescents with WPW. Ablation should be considered as a first-line therapy in asymptomatic children and adolescents with high-risk WPW.

Ultrasound-Guided Versus Conventional Vascular Access for Electrophysiological Catheter Ablation: A Meta-Analysis

Ultrasound-Guided Versus Conventional Vascular Access for Electrophysiological Catheter Ablation: A Meta-Analysis

Remanufactured circular mapping catheters: safety, effectiveness and cost

BackgroundThe use of remanufactured single-use devices (SUDs), including cardiac electrophysiology catheters, has become established in the USA and other health care systems but without much published scientific evaluation on the relative safety or efficacy of these devices. In the United Kingdom (UK), the use of remanufactured SUDs has not been routine. We performed a structured evaluation of the safety and efficacy of a remanufactured circular mapping catheter (Stryker® remanufactured Lasso NAV 2515) during its introduction in our centre.MethodsWe prospectively evaluated the performance of a remanufactured circular mapping catheter in 100 consecutive patients undergoing an AF ablation. Operator feedback was obtained, assessing the device appearance, ease of use and function. As an indirect measurement of efficacy, acute procedure metrics were compared to those in 100 propensity-matched cases performed by the same operators using a new device. Cost savings were calculated.ResultsNo complication occurred in association with the remanufactured device. There was one reported failure of device malfunction—the flexion-extension mechanism of a remanufactured catheter and none in the matched-control group. There was satisfactory communication with the electro-anatomic mapping system. Ease of use of the remanufactured catheter was reported to be similar to a newly manufactured device. Procedural duration was similar with remanufactured devices and matched controls. With 100 cases using the remanufactured device, cost savings amounted to £30,444.ConclusionsThe use of remanufactured circular mapping catheters is safe, efficient and reliable. Widespread use of remanufactured SUDs offers the possibility of significant economic benefit.

Differences in the upslope of the precordial body surface ECG T wave reflect right to left dispersion of repolarization in the intact human heart

BackgroundThe relationship between the surface electrocardiogram (ECG) T wave to intracardiac repolarization is poorly understood.ObjectiveThe purpose of this study was to examine the association between intracardiac ventricular repolarization and the T wave on the body surface ECG (SECGTW).MethodsTen patients with a normal heart (age 35 ± 15 years; 6 men) were studied. Decapolar electrophysiological catheters were placed in the right ventricle (RV) and lateral left ventricle (LV) to record in an apicobasal orientation and in the lateral LV branch of the coronary sinus (CS) for transmural recording. Each catheter (CS, LV, RV) was sequentially paced using an S1–S2 restitution protocol. Intracardiac repolarization time and apicobasal, RV–LV, and transmural repolarization dispersion were correlated with the SECGTW, and a total of 23,946 T waves analyzed.ResultsRV endocardial repolarization occurred on the upslope of lead V1, V2, and V3 SECGTW, with sensitivity of 0.89, 0.91, and 0.84 and specificity of 0.67, 0.68, and 0.65, respectively. LV basal endocardial, epicardial, and mid-endocardial repolarization occurred on the upslope of leads V6 and I, with sensitivity of 0.79 and 0.8 and specificity of 0.66 and 0.67, respectively. Differences between the end of the upslope in V1, V2, and V3 vs V6 strongly correlated with right to left dispersion of repolarization (intraclass correlation coefficient 0.81, 0.83, and 0.85, respectively; P <.001). Poor association between the T wave and apicobasal and transmural dispersion of repolarization was seen.ConclusionThe precordial SECGTW reflects regional repolarization differences between right and left heart. These findings have important implications for accurately identifying biomarkers of arrhythmogenic risk in disease.

Electrophysiological study and radiofrequency catheter ablation in children with supraventricular tachycardias

Electrophysiological study and radiofrequency catheter ablation in children with supraventricular tachycardias

Robust navigation support in lowest dose image setting.

Clinical cardiac electrophysiology (EP) is concerned with diagnosis and treatment of cardiac arrhythmia describing abnormality or perturbation in the normal activation sequence of the myocardium. With the recent introduction of lowest dose X-ray imaging protocol for EP procedures, interventional image enhancement has gained crucial importance for the well-being of patients as well as medical staff. In this paper, we introduce a novel method to detect and track different EP catheter electrodes in lowest dose fluoroscopic sequences based on [Formula: see text]-sparse coding and online robust PCA (ORPCA). Besides being able to work on real lowest dose sequences, the underlying methodology achieves simultaneous detection and tracking of three main EP catheters used during ablation procedures. We have validated our algorithm on 16 lowest dose fluoroscopic sequences acquired during real cardiac ablation procedures. In addition to expert labels for 2 sequences, we have employed a crowdsourcing strategy to obtain ground truth labels for the remaining 14 sequences. In order to validate the effect of different training data, we have employed a leave-one-out cross-validation scheme yielding an average detection rate of [Formula: see text]. Besides these promising quantitative results, our medical partners also expressed their high satisfaction. Being based on [Formula: see text]-sparse coding and online robust PCA (ORPCA), our method advances previous approaches by being able to detect and track electrodes attached to multiple different catheters.

Ventricular Arrhythmias in the Patient with a Structurally Normal Heart.

Ventricular arrhythmias (VAs) are among the most common cardiac rhythm disturbances encountered in clinical practice. Patients presenting with frequent ventricular ectopy or sustained ventricular tachycardia represent a challenging and worrisome clinical scenario for many practitioners because of concerning symptoms, frequent associated acute hemodynamic compromise, and the adverse prognostic implications inherent to these cases. While an underlying structural or functional cardiac abnormality, metabolic derangement, or medication toxicity is often readily apparent, many patients have no obvious underlying condition, despite a comprehensive diagnostic evaluation. Such patients are diagnosed as having an idiopathic VA, which is a label with specific implications regarding arrhythmia origin, prognosis, and potential for pharmacologic and invasive management. Further, a subset of patients with otherwise benign idiopathic ventricular ectopy can present with polymorphic ventricular tachycardia and ventricular fibrillation, adding a layer of complexity to a clinical syndrome previously felt to have a benign clinical course. Thus, this review seeks to highlight the most common types of idiopathic VAs with a focus on their prognostic implications, underlying electrophysiologic mechanisms, unique electrocardiographic signatures, and considerations for invasive electrophysiologic study and catheter ablation. We further address some of the data regarding idiopathic ventricular fibrillation with respect to the heterogeneous nature of this diagnosis.

Novel approach to discriminate left bundle branch block from nonspecific intraventricular conduction delay using pacing-induced functional left bundle branch block

Left bundle branch block (LBBB) has a predictive value for response to cardiac resynchronization therapy as reported by Zareba et al. (Circulation 123(10):1061-1072, 2011). However, based on ECG criteria, the discrimination between complete LBBB and nonspecific intraventricular conduction delay is challenging. We tested the hypothesis that discrimination can be performed using standard electrophysiological catheters and a simple stimulation protocol. Fifty-nine patients were analyzed retrospectively. Patients were divided into groups of narrow QRS (n = 20), wide QRS of right bundle branch block (RBBB) morphology (n = 14), and wide QRS of LBBB morphology (n = 25). Using a diagnostic catheter placed in the coronary sinus, left ventricular activation was assessed during intrinsic conduction as well as during right ventricular (RV) stimulation. In patients with narrow QRS and RBBB, the Q-LV/QRS ratio was 0.43 ± 0.013 (n = 20) and 0.41 ± 0.026 (n = 14), respectively. In patients with LBBB morphology, the Q-LV/QRS split up into a group of patients with normal (0.43 ± 0.022, n = 7) and a group with delayed left ventricular activation (0.75 ± 0.016, n = 18). By direct comparison of the Q-LV/QRS ratio during intrinsic conduction with the Q-LV/QRS ratio during RV pacing leading to a functional LBBB, a clear distinction between a group of "true LBBB" and another group of "apparent LBBB"/nonspecific intraventricular conduction delay (NICD) could be generated. We present a novel and practical method that might facilitate discrimination between patients with apparent LBBB and true LBBB by comparing Q-LV/QRS ratios during intrinsic activation and during RV stimulation. Although this method can already be directly applied, validation by 3D electrical mapping and prospective correlation to cardiac resynchronization therapy (CRT) response will be required for further translation into clinical practice.

What is the most appropriate method for coronary sinus cannulation? The telescopic method or the electrophysiologic method?

ObjectivesThe most challenging stage of cardiac resynchronization therapy (CRT) is coronary sinus cannulation (CS). The aim of this study was to compare coronary sinus cannulation techniques using electrophysiology catheters and coronary angiography catheters.MethodsIn this observational, retrospective and non-randomized study, 87 patients who were eligible for CRT device implantation were screened at Kahramanmaras Sutcu Imam University Hospital between March 2014 and March 2018. Seventy-two patients who met the inclusion criteria were enrolled in the study. The study population was divided into 2 groups: the first group consisted of 36 patients whose coronary sinuses were cannulated via electrophysiology (EP) catheters and the second group included 36 patients who received coronary angiography catheters for coronary sinus cannulation.ResultsThe two groups were similar in terms of the baseline characteristics of the patients. The total fluoroscopy time was less with cannulation using coronary angiography catheters. There were no differences between the two groups in terms of the amount of contrast material and the success of the operations.ConclusionsCoronary sinus catheterization using coronary angiography catheters significantly reduces fluoroscopy time in patients undergoing CRT.

Theuse of an esophageal catheter to check the results of left atrial posterior wall isolation in the treatment of atrial fibrillation.

Left atrial posterior wall isolation (LAPWI) via catheter, surgical, and hybrid techniques is a promising treatment for persistent atrial fibrillation (PersAF). We investigated whether confirmation of LAPWI can be achieved using an esophageal pacing and recording electrode. Patients undergoing PersAF ablation with the intention to achieve LAPWI were enrolled. Two approaches to LAPWI were tested: (1) ablation using endocardial catheter ablation only, and (2) "Staged Hybrid" ablation with thoracoscopic epicardial ablation, followed by endocardial left atrial electrophysiological study and catheter ablation where necessary. Patients enrolled in the study all required further catheter ablation to achieve LAPWI in this group. In both the groups, esophageal recording and esophageal pacing was performed at the start of mapping and electrophysiological study and compared with endocardial electrophysiological findings. This was repeated at the end of the procedure. Twenty patients (16M, four F) were studied. Endocardial electrophysiological study showed that in none of the cases was the posterior left atrial wall electrically isolated at the start of the study. One patient with Barrett's esophagus failed to sense or pace from the esophagus at any point in the study. In the remaining 19/19, esophageal pacing captured the atrial rhythm at the start of the procedure. LAPWI was then achieved in 17/19 using endocardial catheter ablation; retesting at this point showed sensing and capture of the atrium from the esophagus was abolished. In the remainder sensing and capture persisted. Esophageal pacing can be used to confirm or refute electrical isolation of the left atrial posterior wall.

Cardiac electrophysiology catheters for electrophysiological assessments of the lower urinary tract-A proof of concept ex vivo study in viable ureters.

To explore the feasibility of minimally invasive catheter-based electrophysiology studies in the urinary tract. This is a well-known method used in cardiology to investigate and treat arrhythmias. We developed an experimental platform which allows electrophysiological recordings with cardiac catheters and conventional needle electrodes in ex vivo pig ureters. The action potential was triggered by a stimulating electrode. We considered 13 porcine ureters (freshly collected and harvested in organ bath), 7 of which were used to optimize the setup and define the stimulation parameters; we performed the recordings in the remaining six ureters. The electrical propagation of the generated action potential was tracked with multiple sensing electrodes, from which propagation directions, velocities, refractory periods, and pacing thresholds were extracted. We recorded propagating electrical activity in four ureters using needle electrodes and in two ureters using cardiac catheters. Propagation velocities for forward direction (from kidney to bladder) derived by the two methods were similar (15.1 ± 2.6 mm/s for cardiac catheters, 15.6 ± 2.3 mm/s for needle recordings). Pacing thresholds, activation patters, and refractory times were provided for the ureteric smooth muscle. Retrograde propagations and corresponding velocities were also observed and measured. This study is a proof-of-concept showing that electrical activity can be measured "from the inside" of urinary cavities using catheters and that obtained results are comparable with the more invasive needle recordings. Catheter-based electrophysiology may allow, in the clinical setting, for: i) a more differentiated understanding of urological disorders such as overactive bladder and ii) new therapeutic approaches (e.g., targeted tissue ablation).

Arrhythmia-specific settings for automated high-density mapping: A multicenter experience.

Advancements in electrophysiology 3-D mapping systems facilitate the broadening scope of electrophysiology study and catheter ablation to treat complex arrhythmias. While electroanatomical mapping systems have default settings available for a variety of mapping parameters, significant operator customization driven by arrhythmia type and experience can occur. However, multicenter comprehensive reporting of customized mapping settings is lacking. In this prospective, multicenter observational registry, subjects with cardiac arrhythmias underwent electrophysiology study and ablation procedure using the EnSite Precision™ electroanatomical mapping system per standard of care, and associated automated mapping thresholds and procedural characteristics were observed. Cardiac mapping and ablation was performed in 503 patients (64.4% male, 59.6±13.2 years) for a variety of indications including atrial fibrillation (N=277), atrial flutter (N=67), other supraventricular tachycardias (N=96), and ventricular tachycardia (N=56). Automated electroanatomical mapping was used to generate 88.2% of all maps, and arrhythmia-specific adjustments of mapping thresholds were utilized to collect electrophysiologically relevant data. The most commonly used thresholds for mapping in AF were Distance (average 2.7±3.5mm) and Signal-to-Noise Ratio (5.2±1.1), while mapping in VT commonly used Score (88.5±6.5%) and Distance (0.6±0.5mm). Automated mapping collected and utilized 8.8 times more data than manual mapping without increasing mapping time. This registry revealed arrhythmia-specific automated mapping settings used to generate electroanatomical maps of multiple cardiac rhythms with higher point density than manual mapping without increasing mapping time. Commonly used mapping threshold settings could serve as an important reference for new automated electroanatomical mapping users or those expanding their usage to new indications and arrhythmias.

Advances in Clinical Cardiology 2017: A Summary of Key Clinical Trials.

Numerous important cardiology clinical trials have been published or presented at major international meetings during 2017. This paper aims to summarize these trials and place them in clinical context. The authors reviewed clinical trials presented at major cardiology conferences during 2017 including the American College of Cardiology, European Association for Percutaneous Cardiovascular Interventions, European Society of Cardiology, European Association for the Study of Diabetes, Transcatheter Cardiovascular Therapeutics, and the American Heart Association. Selection criteria were trials with a broad relevance to the cardiology community and those with potential to change current practice. A total of 75 key cardiology clinical trials were identified for inclusion. New interventional and structural cardiology data include left main bifurcation treatment strategy, multivessel disease management in cardiogenic shock, drug-eluting balloons for in-stent restenosis, instantaneous wave-free physiological assessment, new-generation stents (COMBO, Orsiro), transcatheter aortic valve implantation, and closure devices. New preventative cardiology data include trials of liraglutide, empagliflozin, PCSK9 inhibitors (evolocumab and bococizumab), inclisiran, and anacetrapib. Antiplatelet data include the role of uninterrupted aspirin therapy during non-cardiac surgery and dual antiplatelet therapy following coronary artery bypass grafting. New data are also included from fields of heart failure (levosimendan, spironolactone), atrial fibrillation (apixaban in DC cardioversion), cardiac devices (closed loop stimulation pacing for neuromediated syncope), and electrophysiology (catheter ablation for atrial fibrillation). This paper presents a summary of key clinical cardiology trials during the past year and should be of practical value to both clinicians and cardiology researchers.

Impact of attributed audit on procedural performance in cardiac electrophysiology catheter laboratory.

Audit has played a key role in monitoring and improving clinical practice. However, audit often fails to drive change as summative institutional data alone may be insufficient to do so. We hypothesised that the practice of attributed audit, wherein each individual's procedural performance is presented will have a greater impact on clinical practice. This hypothesis was tested in an observational study evaluating improvement in fluoroscopy times for AF ablation. Retrospective analyses of fluoroscopy times in AF ablations at the Barts Heart Centre (BHC) from 2012-2017. Fluoroscopy times were compared pre- and post- the introduction of attributed audit in 2012 at St Bartholomew's Hospital (SBH). In order to test the hypothesis, this concept was introduced to a second group of experienced operators from the Heart Hospital (HH) as part of a merger of the two institutions in 2015 and change in fluoroscopy times recorded. A significant drop in fluoroscopy times (33.3 ± 9.14 to 8.95 ± 2.50, p < 0.0001) from 2012-2014 was noted after the introduction of attributed audit. At the time of merger, a significant difference in fluoroscopy times between operators from the two centres was seen in 2015. Each operator's procedural performance was shared openly at the audit meeting. Subsequent audits showed a steady decrease in fluoroscopy times for each operator with the fluoroscopy time (min, mean±SD) decreasing from 13.29 ± 7.3 in 2015 to 8.84 ± 4.8 (p < 0.0001) in 2017 across the entire group. Systematic improvement in fluoroscopy times for AF ablation procedures was noted byevaluating individual operators' performance. Attributing data to physicians in attributed audit can promptsignificant improvement and hence should be adopted in clinical practice.

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System.

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum of physiological, biochemical, morphological, and pharmacological parameters in centrally denervated hearts. Here, we describe a setup for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cyclic adenosine monophosphate (cAMP) dynamics. The intracardiac autonomic nervous system is modulated by the mechanical dissection of atrial fat pads-in which murine ganglia are located mainly-or by the usage of global as well as targeted pharmacological interventions. An octapolar electrophysiological catheter is introduced into the right atrium and the right ventricle, and epicardial-placed multi-electrode arrays (MEA) for high-resolution mapping are used to determine cardiac electrophysiology and arrhythmogenesis. Förster resonance energy transfer (FRET) imaging is performed for the real-time monitoring of cAMP levels in different cardiac regions. Neuromorphology is studied by means of antibody-based staining of whole hearts using neuronal markers to guide the identification and modulation of specific targets of the intracardiac autonomic nervous system in the performed studies. The ex vivo Langendorff setup allows for a high number of reproducible experiments in a short time. Nevertheless, the partly open nature of the setup (e.g., during MEA measurements) makes constant temperature control difficult and should be kept to a minimum. This described method makes it possible to analyze and modulate the intracardiac autonomic nervous system in decentralized hearts.

Idiopathic premature ventricular complexes originating from the distal great cardiac vein: Clinical, cardiac and electrophysiological characteristics and catheter ablation outcome

AimsAlthough catheter ablation for idiopathic ventricular arrhythmia (VA) has been generally well-established, VA originating from the great cardiac vein (GCV) may be clinically challenging due to its epicardial origin, proximity to coronary arteries and limited accessibility. The purpose of this study was to explore its electrophysiological characteristics and identify effective mapping/ablation strategies for idiopathic premature ventricular complexes (PVCs) originating from the GCV. Materials and methodsBetween January 2013 to January 2018, 12 patients (who were diagnosed with PVCs originating from the GCV) among the 305 patients with idiopathic left ventricular outflow tract tachycardia were included. The origin of the ectopy was localized by mapping, the characteristics of the electrocardiogram (ECG) were analyzed, and all the patients with PVCs originating from GCV were treated by radiofrequency catheter ablation (RFCA). The safety and efficacy of RFCA were evaluated. Key findingsThe origin of the ectopy was successfully localized in GCV for all 12 patients by mapping, and access to GCV via the coronary sinus was feasible. Successful RFCA was achieved in 11 of 12 patients (91.67% acute procedural success) without perioperative complications. During a median follow-up of 12.6 ± 6.5 months, only one patient had recurrent VA (recurrence rate: 9.1%). SignificanceECG characteristics may be helpful for identifying patients with PVCs originating from the GCV. RFCA within the coronary venous system appears to be safe and effective for these patients, and should be considered when routine RFCA from the endocardium or aortic sinus of the Valsalva is not effective.