Outflow Tract Arrhythmias Research Articles

Evaluation of five algorithms in predicting the sublocalisation of right ventricular outflow tract arrhythmia (RVOTA) when compared to 3D electroanatomical mapping origin

PurposeTo compare the predictive accuracy of five different algorithms as verified by successful ablation site using 3D electroanatomical non-contact mapping in patients with symptomatic and asymptomatic but high ventricular burden RVOT tachycardias.Methods28 Consecutive patients admitted for radiofrequency catheter ablation for symptomatic and asymptomatic, but high ventricular burden idiopathic VPC were recruited for this study. All patients had previous failed or intolerant to beta-blocker and/or at least one class IC anti-arrhythmic agents, and they had normal left ventricular ejection fraction. All patients had documented monomorphic VPC with left bundle branch block morphology and an inferior axis. Concordance of the arrhythmia origin based on ECG algorithm and 3D mapping system site were further evaluated. Of the five algorithms, two algorithms with easy‐applicability and having a memorable design (Dixit and Joshi) and three algorithms with more complex and detailed design (Ito, Zhang, Pytkowski) were selected for comparisons.ResultsAssessment of the diagnostic accuracy showed that each of the five algorithms had only moderate accuracy, and the greatest accuracy was observed in the algorithm proposed by Pytkowski algorithm when assessed by a general cardiologist and Dixit algorithm when evaluated by the electrophysiologist. However, when the algorithms were compared for their accuracy, specificity, sensitivity, no significant differences were found (p = 0.99).ConclusionsThe ECG based algorithms for precise localising RVOTA origin simplify the mapping process, reduce the procedural and fluoroscopic time, and improve clinical outcomes, resulting in greater clinical utility. All the five published 12-lead ECG algorithms for ROTVA differentiation were similar in terms of the diagnostic accuracy, specificity, sensitivity and LRs.

An electrocardiographic diagnostic model for differentiating right from left ventricular outflow tract arrythmias origin

Abstract Background/Introduction Several ECG signs have been proposed to discern the focal origin of ventricular outflow tract arrhythmias with a transition ≥V3. Their independent predictive value is unclear. Purpose The aim of the study is to establish a predictive model of independent ECG parameters to obtain an acute success in right-sided catheter ablation of isolated premature ventricular contractions (PVCs) or ventricular tachycardia (VT) from the ventricular outflow tract with a transition ≥V3. Methods We included 122 patients (62 women, mean age 54±16 years) with documented PVCs or VT showing a lower axis and predominantly negative QRS complexes in V1 and V2 who underwent ablation between January 2014 and June 2020. The achievement of acute ablation success from right endocardial positions was assessed. We performed a predictive model by multivariate logistic regression analysis including the following ECG variables associated with a right origin of the ventricular focus in previous studies: Transitional Zone (TZ) index, V2 transition ratio, V2S / V3R index, R-wave duration index, R/S-wave amplitude index in V2, variable coupling interval, and the presence of QS morphology in lead I. Results Two independent predictive ECG variables were identified: the V2S / V3R index (odds ratio 1.223; 95% CI, 1.024–1.460; p=0.026) and a coupling interval variability >60 ms (odds ratio 0.307; 95% CI, 0.129 - 0.731; p=0.008). The area under the curve of this model was 0.733 (Picture 1). Arrhythmias with transition in V3 present a greater electroanatomic overlap and, therefore, a higher probability of right failure (59.3% vs 73.5% in arrhythmias with transitions after V3). In these, the V2 transition ratio is useful to predict the origin of the ectopy. Conclusion Two easily identifiable ECG variables (the V2S / V3R index and coupling interval variability >60 ms) predict the acute success of a right-sided approach in the ablation of focal ventricular arrhythmias with predominantly negative QRS complexes in V1 and V2. Funding Acknowledgement Type of funding sources: None. Predictive accuracy of the ECG model

Differentiating the origin of outflow tract premature ventricular complexes using the QRS-right ventricular apex interval

Abstract Background For localization of outflow tract Premature ventricular complexes (PVCs) many ECG criteria have been proposed, however in some cases it is difficult to accurately localize the origin of PVCs using the surface ECG. Objective This study aims to study the relation between QRS-right ventricular apex interval and the origin of the outflow tract PVCs. Patients and Methods The study included 30 patients (27 female, age 37.20 ± 7.87, RVOT origin 18) referred for PVCs ablation and we measured the interval from the onset of the earliest QRS complex of premature ventricular contractions (PVCs) to the distal right ventricular apical signal, (the QRS-RVA interval) and correlated this interval with origin of outflow tract PVCs as identified by the successful ablation during the procedure. Results Compared to PVCs originating from RVOT, the QRS-RVA interval was significantly longer in PVCs originating from LVOT (67.33±7.56 for LVOT PVCs vs. 37.11±4.34 for RVOT PVCs, p < 0.001). Receiver operating characteristic (ROC) analysis showed that a QRSRVA interval ≥47 ms has a sensitivity, specificity, positive and negative predictive values of 100%, 100%, 100%, 100% respectively, for prediction of an LVOT origin of PVCs Conclusion The QRS-RVA interval is a simple and accurate criterion for differentiating the origin of outflow tract arrhythmia during electrophysiology study, A QRS-RVA interval ≥47 ms suggests an LVOT origin of PVCs.

Cardiac magnetic resonance imaging in right ventricular outflow tract arrhythmia: a retrospective analysis from a tertiary care centre in South India

Introduction Arrhythmia arising from right ventricular outflow tract (RVOT) is the most common cause of idiopathic ventricular arrhythmia. Previous studies involving cardiac magnetic resonance imaging (MRI) in these patients are known to show abnormalities in up to 60% of patients. Methodology This was a retrospective descriptive analysis of patients having idiopathic RVOT arrhythmia who underwent cardiac MRI between January 2010 and December 2020. Clinical and demographic details were recorded from the electronic medical records and cardiac MRI of all patients were reviewed. Results Among 214 patients with RVOT arrhythmia, 64 underwent cardiac MRI. A total of 41 patients, who did not have any abnormality on baseline echocardiogram were included in the study. There was male preponderance (56.1%), with median age of 43 years. About 43.9% had syncope. Twenty-four-hour Holter study revealed a premature ventricular complex (PVC) burden of 26.3 ± 11.7%. MRI showed structural abnormalities in 51.2% of patients, which commonly included RV sacculations and aneurysms. Late gadolinium enhancement (LGE) was seen in six patients, which was mostly seen in RV free wall. Right ventricular (RV) systolic dysfunction was evident in 29.3%. About 9.8% fulfilled the criteria for arrhythmogenic RV cardiomyopathy (ARVC). Out of 23 patients with baseline abnormalities on ECHO, 87% had structural abnormalities on MRI, and 43.5% fulfilled the criteria for ARVC. Conclusions Additional imaging by cardiac MRI helps to identify structural abnormalities in 51.2% of patients with RVOT arrhythmias, even with normal baseline echocardiogram and electrocardiogram (ECG). It is useful tool to rule out ARVC in this subset of patients, and can help in increasing the diagnostic yield in the early stages.

Utility of high resolution mapping to guide ablation of ventricular arrhythmias from the aortic sinuses of Valsalva.

Left ventricular outflow tract (LVOT) arrhythmias are commonly targeted from the aortic sinuses of Valsalva (SOV). Both presystolic potentials during ventricular arrhythmia (VA) and late diastolic potentials during sinus rhythm have been recognized as markers of successful ablation sites. The study aimed to evaluate the utility of high resolution mapping (HRM) with small and closely spaced electrodes for guiding ablation of VA from the SOV. Seventeen patients with LVOT VA underwent HRM in the SOV with either PentaRay (13) or Orion (4) catheters. Ablation was guided by low amplitude high frequency potentials that were identified with HRM and tagged on the electroanatomic map. High frequency low amplitude potentials during sinus rhythm (late) or VA (early) were demonstrated with HRM in all 17 consecutive patients; while these potentials were either absent or usually had a far-field appearance in the recordings obtained at the same sites with a 3.5-mm standard ablation catheter. On intracardiac echocardiogram, sites with these potentials corresponded to the bases of the sinuses adjacent to the LV ostium. Ablation was acutely successful in 16 out of 17 patients. Significant reduction in VA burden (≥ 90%) was noted in 15 patients. High frequency low amplitude potentials during sinus rhythm (late) and VA (early) are consistently recorded using HRM in the SOV in patients with VA arising from the aortic sinuses of Valsalva. Standard ablation catheters have limited resolution for detecting these potentials. HRM may potentially improve outcomes of ablation of VA originating from the aortic SOV.

Features Suggesting Preferential Conduction in Pulmonary Artery Ventricular Arrhythmia for Identification of Successful Ablation Sites.

Radiofrequency catheter ablation (RFCA) for pulmonary artery ventricular arrhythmia (PAVA) can be difficult because of the occasional existence of PAVA with preferential conduction.This study described the characteristics of PAVA that demonstrate preferential conduction.We analyzed electrocardiographic and electrophysiological data from 8 patients found to have PAVAs with preferential conduction out of 183 patients (4.4%) with right ventricular outflow tract (RVOT) arrhythmias who underwent RFCA at our hospitals. The PAVA with preferential conduction were classified into two types. In type 1 PAVA, successful ablation sites (success-sites) exhibited discrete prepotentials with an isoelectric line, in which the activation time (AT) was ≥ 50 milliseconds. In type 2 PAVA, excellent pace mapping was achieved at two sites separated by ≥ 20 mm: one in the RVOT free wall and the other at the success-site in the pulmonary artery. Type 1 and 2 PAVA features were considered signs of a short and long preferential conduction pathway, respectively.There were four patients each with type 1 and 2 PAVA. Type 1 PAVA was distinguished by the isoelectric line at success-sites with the mean AT of 78 ± 25.1 milliseconds. In type 2 PAVAs, although the AT at RVOT sites was very short (18.5 ± 10.1 milliseconds), the AT at success-sites was longer than that at the RVOT by 42.3 ± 36.2 milliseconds. Type 2 PAVAs displayed distinct electrocardiogram (ECG) features (R wave in lead I, RR' in inferior leads, and transitional zone in V4) not found in typical PAVA ECGs.PAVA with preferential conduction can manifest in distinct ways on the ECG and intracardiac mapping. Knowledge of these features may facilitate successful RFCA of such PAVA cases.

Prognostic value of time dependent voltage abatement during remote magnetic navigation guided ablation in idiopathic right ventricular outflow tract arrhythmias

Kontext: NaĹĄĂ­m cĂ­lem bylo zjistit, zda časově zĂĄvislĂŠ snĂ­ĹženĂ­ voltĂĄĹže (dV/dt) na komorovĂ˝ch elektrogramech (EGM) během katetrizačnĂ­ ablace idiopatickĂ˝ch arytmiĂ­ z vĂ˝tokovĂŠho traktu pravĂŠ komory (right ventricular outflow tract, RVOT) s pouĹžitĂ­m systĂŠmu Stereotaxis Niobe II představuje účinnĂ˝ ukazatel dlouhodobĂŠ Ăşspěšnosti vĂ˝konu. Metody: Do studie bylo zařazeno 26 po sobě nĂĄsledujĂ­cĂ­ch pacientĹŻ s akutnĂ­ Ăşspěšnou ablacĂ­ RVOT pro předčasnĂŠ komorovĂŠ stahy (premature ventricular contractions, PVC) a/nebo komorovĂŠ tachykardie (KT) s pĹŻvodem nejspĂ­ĹĄe v RVOT. PozdnĂ­ Ăşspěšnost byla definovĂĄna jako vymizenĂ­ komorovĂ˝ch ektopiĂ­ z RVOT po tříměsíčnĂ­m sledovĂĄnĂ­ bez antiarytmik (antiarrhythmic drug, AAD). VĂ˝sledky: Po tříměsíčnĂ­m sledovĂĄnĂ­ vymizely symptomy i arytmie u 20 (skupina 1) z 26 pacientĹŻ (77 %), přičemĹž k recidivě doĹĄlo u ĹĄesti pacientĹŻ (23 %) (skupina 2). Během RF ablace byl "warming up" fenomĂŠn pozorovĂĄn u 85 %, resp. 83,33 % pacientĹŻ (p = 0,46) po prĹŻměrnĂŠ době (dt 2) 4,72 ± 9,42, resp. 10,75 ± 11,34 s (p = 0,045). Doba od zahĂĄjenĂ­ aplikace RF energie (t0) do vĂ˝znamnĂŠho snĂ­ĹženĂ­ voltĂĄĹže (> 90 %) nebo obrĂĄcenĂ­ polarity EGM (t1) u obou skupin činila 9,11 ± 5,11, resp. 32,16 ± 10,33 (p = 0,00006). Hodnota dV/dt1 byla 95,44 ± 87,6, resp. 23,5 ± 16,97 μV/s (p = 0,024). ZĂĄvěr: Časově zĂĄvislĂŠ snĂ­ĹženĂ­ voltĂĄĹže na komorovĂŠm EGM spolu s dobou od zahĂĄjenĂ­ RF ablace do vĂ˝znamnĂŠho snĂ­ĹženĂ­ voltĂĄĹže (> 90 %) nebo obrĂĄcenĂ­ polarity EGM a dobou od aplikace RF energie do vzniku "warming up" fenomĂŠnu představujĂ­ moĹžnĂŠ prediktory dlouhodobĂŠ Ăşspěšnosti RF ablace idiopatickĂ˝ch arytmiĂ­ vychĂĄzejĂ­cĂ­ch z RVOT. © 2021, ČKS.

Periaortic Ventricular Tachycardias in Nonischemic Cardiomyopathy: Substrate and Electrocardiographic Correlations.

Periaortic fibrotic ventricular tachycardia (VT) substrate is common in nonischemic cardiomyopathy (NICM), often intramural, and difficult to ablate. We sought to better characterize normal and abnormal periaortic voltage map parameters and NICM periaortic VTs. In 15 patients without heart disease, the 5th percentile of endocardial voltage for increasing distance from the aortic valve ring was determined. In 53 consecutive patients with NICM (64±11 years; left ventricular ejection fraction 31±10%) undergoing ablation of recurrent VT, periaortic electrogram voltage and VT characteristics were analyzed. In healthy patients, the fifth percentile of the bipolar voltage increased proportional to the distance from the aortic valve ring, from 1.0 mV at 1 cm to 1.5 mV at 1.5 cm; the corresponding unipolar voltage cutoffs were 5.0 and 7.5 mV. A total of 160 VTs were induced in 53 patients with NICM, of which 28 VTs in 20 patients had periaortic origins. Periaortic VTs were associated with similar periaortic bipolar voltage, but lower UVs consistent with intramural fibrosis as an important substrate. Periaortic VTs could be divided into left and right bundle branch block forms with mapping showing right septal and lateral exits. Left bundle branch block VTs were more often acutely abolished with ablation (100% versus 69%; P=0.034), but with a 23% incidence of heart block. Greater extent of low voltage was associated with more induced VTs and worse acute outcome. Adjusting voltage parameters based on distance from the aortic valve may improve definition of left ventricular outflow tract arrhythmia substrate. Periaortic VTs are common in NICM, often associated with intramural substrate and can be divided into left bundle branch block and right bundle branch block types associated with different ablation outcomes and risks.

Surface unipolar electrogram characteristics to predict site of origin of outflow tract arrhythmias using noninvasive mapping.

Noninvasive electroanatomic mapping (NIEAM) demonstrate patterns of depolarization that are useful in identifying the chamber of origin (COO) in outflow tract ventricular arrhythmias (OTVA). However, its use in predicting exact site of origin (SOO) has not yet been validated. NIEAMs (CardioInsight, Medtronic) from 40 patients (age 62.5 ± 2.6) undergoing ablation for OTVA were reviewed for diagnostic accuracy in predicting the SOO. Earliest arrhythmia breakout and directionality of earliest instantaneous unipolar electrograms (uEGMs) on NIEAMs were evaluated subjectively by two observers for quality and amplitude. Sites with most negative earliest uEGMs on right and left ventricular outflow tracts, as well as epicardial surface were manually identified. Using NIEAM-based activation timing of the lateral mitral annulus and basal septum COO was identified for each OTVA. Predictions of SOO using NIEAMs was compared with true SOO from invasive study. NIEAMs SOO predictions were compared with subjective 12 lead electrocardiogram (ECG) review by two observers. Review of arrhythmia breakout and signal directionality had poor diagnostic value in predicting SOO in OTVA (50.6% and 49.4%, 56.6% and 43.4%, respectively) and underperformed compared with ECG interpretation (59.1% and 80.5%). After excluding uEGMs with poor characteristics, the uEGM with most negative amplitude at the COO was predictive of the true SOO with 96.4% sensitivity and specificity. We propose a stepwise approach when interpreting NIEAMs for OTVA where patterns of activation are evaluated first to determine the COO, followed by identification of the site with most negative amplitude instantaneous uEGM to determine SOO.

Precordial T-Wave Inversions in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy Who Present with the Initial Features of Right Ventricular Outflow Tract Arrhythmia.

Precordial T-wave inversion (TWI) is an important diagnostic criterion for arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aimed to characterize the initial repolarization features of definite ARVC in patients who first presented with right ventricular outflow tract ventricular arrhythmia (RVOT-VA) and TWI. Patients who presented with RVOT-VA and TWI ≥ V2 were retrospectively assessed. The initial characteristics of repolarization between patients with and without a final diagnosis of definite ARVC during follow-up were compared. TWI ≥ V2 was observed in 61 of 553 patients (mean age: 44.1 ± 14.7 years; 14 men) with RVOT-VAs. After an average follow-up time of 54.9 ± 33.7 months, 31 (50.8%) patients were classified into the definite ARVC group and 30 (49.2%) into the non-definite ARVC group. The disappearance of precordial TWI ≥ V2 was observed in eight (13.1%) patients after the elimination of RVOT-VAs. In a multivariate analysis of the initial electrocardiogram features, only fragmented QRS [odds ratio (OR): 15.45, 95% confidence interval (CI): 1.61-148.26, p = 0.02] and precordial V2 TpTe interval (OR: 1.03, 95% CI: 1.01-1.06, p = 0.02) could independently predict definite ARVC during longitudinal follow-up. An initial V2 TpTe cutoff value > 88.5 ms could predict the final diagnosis of definite ARVC, with a sensitivity and specificity of 74.2% and 78.6%, respectively. Despite the high risk of ARVC in RVOT-VAs and TWI ≥ V2, "normalization" of TWI was observed after ventricular arrhythmia elimination in 13.1% of the patients. Fragmented QRS and longer V2 TpTe interval were associated with definite ARVC during longitudinal follow-up.

Contact-force monitoring increases accuracy of right ventricular voltage mapping avoiding “false scar” detection in patients with no evidence of structural heart disease

PurposeElectroanatomical mapping (EAM) could increase cardiac magnetic resonance imaging (CMR) sensitivity in detecting ventricular scar. Possible bias may be scar over-estimation due to inadequate tissue contact. Aim of the study is to evaluate contact-force monitoring influence during EAM, in patients with idiopathic right ventricular arrhythmias. Methods20 pts (13 M; 43 ± 12 y) with idiopathic right ventricular outflow tract (RVOT) arrhythmias and no structural abnormalities were submitted to Smarttouch catheter Carto3 EAM. Native maps included points collected without considering contact-force. EAM scar was defined as area ≥1 cm2 including at least 3 adjacent points with signal amplitude (bipolar <0.5 mV, unipolar 3,5 mV), surrounded by low-voltage border zone. EAM were re-evaluated offline, removing points collected with contact force <5 g. Finally, contact force-corrected maps were compared to the native ones. ResultsAn EAM was created for each patient (345 ± 85 points). After removing poor contact points, a mean of 149 ± 60 points was collected. The percentage of false scar, collected during contact force blinded mapping compared to total volume, was 6.0 ± 5.2% for bipolar scar and 7.1 ± 5.9% for unipolar scar, respectively. No EAM scar was present after poor contact points removal. Right ventricular areas analysis revealed a greater number of points with contact force < 5 g acquired in free wall, where reduced mean bipolar and unipolar voltage were recorded. ConclusionsTo date this is the first work conducted on structurally normal hearts in which contact-force significantly increases EAM accuracy, avoiding “false scar” related to non-adequate contact between catheter and tissue.

Contact- versus noncontact-guided ablation of the right ventricular outflow tract arrhythmias: A propensity score matched analysis.

There are unique advantages and disadvantages in the choice of contact mapping (CM) versus noncontact mapping (NCM) systems during ablation of right ventricular outflow tract (RVOT) arrhythmias. This study compared acute procedural success and clinical outcomes in matched patients undergoing CM- versus NCM-guided RVOT ablation. A total of 167 consecutive patients with idiopathic RVOT ventricular arrhythmias underwent NCM- or CM-guided ablation. Propensity scoring was used to match each patient undergoing NCM-guided ablation to one control patient undergoing CM-guided ablation. A total of 120 patients were included in this final analysis. If initial ablation was acutely unsuccessful in either group, patients crossed over to the other group. Ablation was acutely successful in 47 of 60 (78.3 %) patients in the NCM group and 55 of 60 (91.7%) in the CM group (P=.002). Thirteen NCM patients required CM and two CM patients crossed over to utilize NCM (P=.002). Procedural duration, fluoroscopy time, and dose in NCM were greater than that in CM (P<.05, respectively). However, procedural complications were not different between two groups. During a mean follow-up of 51 ± 20.6 months, 51 of the 60 NCM patients remained free of arrhythmia, while 48 of the 60 CM patients had no recurrent arrhythmias (P=.47). Contact mapping, compared to NCM, is the superior initial technique to guide RVOT arrhythmia ablation due to a higher procedural success without the need to switch to alternative mapping techniques and shorter procedural and fluoroscopic times.

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 resultsA 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%). ConclusionA combined use of LAPT and IMSDL may be helpful as an additional criterion for ST judgement.

Left sinus of Valsalva-Electroanatomic basis and outcomes with ablation for outflow tract arrhythmias.

The ablation of outflow tract premature ventricular contractions (PVCs) is generally safe and effective. In some patients, successful ablation sites may not correlate with the earliest activation. We sought to evaluate mechanistic and anatomic relevance of the region below the left sinus of Valsalva in variable morphology outflow tract ventricular arrhythmias. PVC cases where ablation was in the region inferior to the left sinus of Valsalva were identified. Procedural and demographic information and long-term outcomes were obtained. Cadaver dissections to evaluate regional anatomy were done as well. A total of 51 cases were included (age 53 ± 10; 37 [73%] males). Ablation was done for high PVC burden (>20%; mean 27% ± 8%) and presence of symptoms (73%) or ejection fraction less than 50% (78%). QRS morphology included either R wave (8; 16%), Rs (9; 18%), or rS (67%) in lead I, no precordial transition (40; 78%), V2 transition, (7; 14%), or V3 transition (4; 8%). In 31 (61%), the site just below the left coronary cusp was the earliest site, while the remainder had another site earlier. Ablation was acutely successful in 50 of 51 (98%). After 3 months, success was noted in 48 of 51 (94%). In two patients, repeat ablation in the same region resulted in durable suppression. The cases presented emphasize the importance of a region centered below the left sinus of Valsalva, where multivariable morphology QRS may be successfully ablated. Consideration of mapping and ablation even when signals are late in this region may be warranted in previously failed ablation attempts or first-line evaluation.

Mapping and Ablation of Ventricular Outflow Tract Arrhythmias.

Arrhythmias arising from the ventricular outflow tracts are commonly encountered. Although largely benign, they can also present with heart failure and sudden cardiac death. Mapping and ablation of these arrhythmias is commonly performed in the electrophysiology laboratory with a high success rate, but occasionally can prove challenging to abolish. This article discusses the mapping and ablation of outflow tract arrhythmias and the challenges that can be overcome by a systematic approach.

Electrocardiographic features, mapping and ablation of idiopathic outflow tract ventricular arrhythmias.

Idiopathic outflow tract ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. These arrhythmias have focal origin and display characteristic electrocardiographic features. The purpose of this article is to review the state of the art of diagnosis and treatment of idiopathic outflow tract ventricular arrhythmias. We systematically reviewed scientific literature about idiopathic outflow tract ventricular arrhythmias selecting the most relevant papers on this topic. The right ventricle outflow tract is the most common site of origin for outflow tract ventricular arrhythmias, but also left ventricle outflow tract can harbour these arrhythmias. Outflow tract ventricular arrhythmias are generally benign and may require treatment if they are symptomatic, incessant or give rise to cardiomyopathy. Radiofrequency catheter ablation is an effective and safe therapeutic strategy. A successful procedure requires a thorough preoperative analysis of the 12-lead electrocardiogram of the spontaneous arrhythmia combined with a detailed electroanatomical mapping and intracardiac echocardiography. Idiopathic outflow tract arrhythmias are frequent in daily clinical practice and can be successfully eliminated through discrete radiofrequency catheter ablation with low rates of complications.

Prognostic Value of Time Dependent Voltage Abatement During Remote Magnetic Navigation Guided Ablation in Idiopathic Right Ventricular Outflow Tract Arrhythmias

scholarly articles on cardiology Journal of Cardiology & Cardiovascular Therapy is an Open Access, international peer reviewed journal launched from Juniper Publishers. Cardiology is a branch of medicine deals with the disorders of heart that keeps cardiologists up to date with advances in the diagnosis and treatment of cardiovascular diseases.

Magnetic resonance imaging abnormalities in the basal interventricular septum of patients with left ventricular outflow tract arrhythmias.

Concealed structural abnormalities were detected by delayed enhancement - magnetic resonance imaging (DE-MRI) in patientswith apparently idiopathic tachycardia of left ventricular (LV) origin. Basal septal fibrosis was evaluated as a potential arrhythmia substrate in patients with left ventricular outflow tract (LVOT) arrhythmias. A total of 22 patients with LVOT arrhythmias, including frequent monomorphic premature ventricular complexes (PVCs) in 15 patients and ventricular tachycardia (VT) in 7 patients, underwent catheter ablation and DE-MRI. A total of 19 patients with frequent PVCs and 17 patients with idiopathic VT of other origin served as a control group. Basal septal intramural fibrosis as thin strip-shaped intramyocardial DE or as marked intramyocardial DE involving >25% of wall thickness was detected more frequently in patients with LVOT arrhythmias (41% and 32%) than in patients with non LVOT arrhythmias (14% and 3%). After successful ablation, 4/16 patients with basal septal intramural fibrosis and LVOT PVCs (n = 3) or LVOT VT (n = 1) compared with no patient without basal septal fibrosis experienced episodes of sustained VT with similar or different QRS morphology resulting in ICD therapy in three patients. Follow-up DE-MRI after PVC ablation (17 ± 7 months) revealed an increase in LV ejection fraction from 49 ± 5% to 56 ± 5% (n = 9) but the amount of septal DE remained unchanged. Basal septal intramural fibrosis may serve as the arrhythmia substrate in a substantial part of patients with premature ventricular complexes (PVCs) and VT originating from the LVOT and identifies patients with continued risk for VT recurrence after initially successful ablation of LVOT arrhythmias.

Electrophysiological characteristics of the earliest activation site in idiopathic right ventricular outflow tract arrhythmias under mini‐electrode mapping

Right ventricular outflow tract ventricular arrhythmias (RVOT VAs) often originate in the voltage-transitional zone. The target electrogram could be compromised by the architecture of the roving catheter. Mini-electrodes could improve the mapping resolution, especially in low-voltage areas. The aim was to assess the electrophysiological characteristics of the earliest activation site (EAS) of RVOT VAs during mapping using mini-electrodes. Twenty-seven patients with RVOT-type VAs were mapped using Orion mini-electrodes and the Rhythmia mapping system. Bipolar and unipolar electrograms were analyzed and compared with conventional ablation catheter recordings. Twenty-five patients (25 of 27) were successfully mapped and ablated at the RVOT. At the EAS, all 25 (100%) patients exhibited local sharp potentials (spiky potential) at the VAs, and 88% (22 of 25) individuals showed reverse late potentials in adjacent sinus beats on the bipolar mini-electrode recordings. Related unipolar electrograms manifested 20% "q-plateau-QS," 76% "gross QS," and 4% "late QS" patterns related to spiky potential voltages and advanced times. Compared with electrograms recorded by ablation catheter, bipolar mini-electrode recordings exhibited significantly shorter spiky potential durations (P = 0.001) and a significantly increased incidence of the reverse late potentials (P = 0.041). Unipolar mini-electrode recordings had a lower incidence ratio of "late QS" patterns (P = 0.039). Compared with ablation catheter mapping, mini-electrodes improved the mapping resolution of the EAS of RVOT VAs and exhibited shorter spiky potential durations and reduced incidence of "later QS" unipolar patterns.

The anatomic substrates for outflow tract arrhythmias

Much has been learned regarding the cellular and molecular mechanisms involved in producing idiopathic ventricular tachycardias originating from the ventricular outflow tract. Questions remain, however, regarding their genesis. In part, this reflects the uncertainty regarding the anatomic arrangement of their myocardial components. This is exacerbated by the lack of consensus regarding the appropriate terms to describe their components, as shown by the current use of "cusp," used interchangeably to describe either the valvar sinuses or the leaflets of the arterial valves. Such uncertainty can be resolved only by providing precise definitions of leaflets, sinuses, and the sinutubular junction. Further problems are created when the arterial roots are described in an attitudinally incorrect manner. Current techniques reveal the location of the cardiac components as they are positioned within the thorax. In this review, we discuss these potential difficulties, putting them into the context of the anatomy of the ventricular outflow tracts as revealed by virtual dissection of computed tomographic datasets. We provide a brief account of cardiac development, suggesting that such evidence can provide vital clues to the potential origins of arrhythmias originating from the myocardial components of the ventricular outflow tracts.