Idiopathic Ventricular Arrhythmias Research Articles

Cryoablation of ventricular tachycardia using ultra-low temperature technology: acute success and insights from the post-interventional CMR

Abstract Background Radiofrequency catheter ablation (RFCA) has good acute and long-term success rates in idiopathic and ischemic ventricular arrhythmia (VA). Drawbacks of the RFCA are reversibility of the edema and limited penetration of the RF energy into the tissue which explain a worse effectiveness in midmyocardial substrates. In comparison to RFCA, the lesions produced by ultra-low temperature cryoablation (ULTC) which uses near-critical nitrogen cryogen at -1960C can be both deeper and irreversible, depending on the duration of the freeze. Purpose We aimed to evaluate the acute effectiveness of a new ULTC technology for VA by examining post-interventional cardiac magnetic resonance images (CMR) with late gadolinium enhancement (LGE), as a part of multi-center Cryocure-VT study. Methods Between December 2022 and May 2023, we ablated 6 patients (age 63±16%; 5 male) with sustained VA and structural heart disease. Three patients had previous myocardial infarction; 1 cardiac sarcoidosis, 1 LMNA/C dilated cardiomyopathy and 1 post-myocarditis VA. LGE-CMR was available in all patients before the ULTC. At first, electro-anatomical mapping and VA induction were performed followed by ULTC using transseptal access. Each application consisted of freeze-thaw-freeze cycle with freeze duration at operator’s discretion based on manufacturer-recommended duration-depth curve. At the end, induction protocol was repeated to assess the acute success. Additionally, LGE-CMR was performed after ablation as an attempt to visualize the cryo-lesions. Results Median of 6 applications (IQR 4.75-7.5) of cryo-energy were applied per patient. Median procedure time was 180 min (IQR 97-180), and median fluoroscopy time of 20 min (IQR 15-26). Septal VA exits were detected in 3/6 patients; in 1 the exit was at aorto-mitral continuity; in 2 – basal inferior. After ablation, no VAs were inducible in 5/6 (83%) patients. The only patient with failure to ablate all VAs had fewer applications (n=4) and shorter freeze duration of 30 sec., as compared to the rest. Post-procedural CMR revealed new LGE with up to 75% transmurality in 5/6 patients; microvascular obstruction in 4/6 patients. Only LV edema, but no LGE was observed in the patient with shortest freeze time, who also had intra-hospital recurrence. No complications occurred. Conclusions Cryoablation of VA using a new ultra-low temperature technology is effective and safe to ablate VT even in patients with mid-septal substrates. New LGE in result of ULTCA can be observed in CMR and the lesions depth depends on the duration of application.

Application of high-power ablation mode in patients with idiopathic ventricular extrasystole

Background. A new method of high-power short-duration ablation (HPSDA) with high impact energy, ranging from 60 to 90 W, is becoming widespread in the world. However, the number of studies on the use of HPSDA in patients with idiopathic ventricular arrhythmias (IVA) is limited. It is relevant to study the feasibility of using HPSDA to improve the outcomes of radiofrequency ablation (RFA) in patients with IVA. The aim of the study: to evaluate the immediate results of HPSDA in RFA for IVA and to compare it with the classic ablation mode. Materials and methods. We have retrospectively analyzed the results of RFA in 54 patients with symptomatic IVA. Their average age was 45.0 ± 11.7 years. The majority were men (72.3 %). Given the possible effect of intracardiac mapping on the results of ablation, the patients were divided into two groups. Group I include 27 (50 %) participants in whom mapping was performed using 3D navigation. Group II include 27 (50 %) patients in whom 3D navigation was not used. The decision to use HPSDA or classic ablation was made empirically, without considering any factors or characteristics of a patient. The following ablation parameters were used during HPSDA: temperature 45 °C, exposure time 7 seconds, energy 70 W. Results. In group I, where 3D navigation was used to localize the substrate, HPSDA was performed in 12 patients (44.4 %), and the classic mode was used in 15 cases (55.6 %). With conventional mapping, HPSDA was applied in 10 (37.0 %) patients, and the classic mode in 17 (63.0 %). Сlassic ablation allowed to achieve complete arrhythmia suppression in all patients, regardless of the mapping method. When using only HPSDA, the disappearance of arrhythmia was observed only in 45.5 % of cases. With the use of the classic mode, recurrence of IVA during the control time was observed in 16.6 % of patients, while with the use HPSDA in 33.3 %. Conclusions. The high-power regimen demonstrated significantly lower efficacy for permanent suppression of IVA compared to classic ablation methods (p = 0.007). The use of HPSDA to suppress IVA is associated with a high risk of arrhythmia recurrence during control time (p = 0.0010). It is advisable to convert the ablation mode for complete suppression of arrhythmia when the HPSDA is ineffective.

Trends Favoring an Anatomical Approach to Radiofrequency Catheter Ablation of Idiopathic Ventricular Arrhythmias Originating From the Left Ventricular Summit.

Epicardial radiofrequency catheter ablation (RFCA) of idiopathic ventricular arrhythmias (VAs) originating from the left ventricular summit (LVS) is challenging because of the anatomic barriers. On the other hand, RFCA at the endocardial sites near the earliest epicardial activation site of LVS-VAs (anatomic approach) has proven successful. The evolving trends in the approaches and outcomes of RFCA of LVS-VAs at a single center were evaluated. We studied 88 consecutive patients with idiopathic LVS-VAs at our institute from 2009 to 2019. These patients were divided into 3 periods: 2009 to 2012 (early), 2013 to 2015 (middle), and 2016 to 2019 (recent). The data were compared among the 3 periods. The RFCA success rate did not significantly change from the early to middle period but significantly increased from the middle to recent period (P=0.0315). The transpericardial approach usage significantly decreased over the 3 periods. The anatomic approach usage significantly increased over the 3 periods. The use of the transpericardial approach did not affect the RFCA outcomes over the 3 periods. The success rate of the anatomic RFCA tended to increase from the early to middle period and significantly increased from the middle to recent period (P=0.0412). The number of endocardial locations where RFCA was successful increased over the 3 periods. Over the 10-year period, the transpericardial approach became decreasingly performed, whereas the anatomic approach became increasingly performed with a satisfactory improvement in the RFCA outcomes of LVS-VAs. The anatomic RFCA became more successful by identifying more and various endocardial locations as target sites.

Prevalence and electrocardiographic and electrophysiological characteristics of idiopathic ventricular arrhythmias originating from the septal left ventricular summit.

The left ventricular summit (LVS) is the highest point on the epicardial surface of the left ventricle. A part of the LVS that is located between the left coronary arteries (lateral-LVS) is one of the major sites of idiopathic ventricular arrhythmia (VA) origins. Some idiopathic epicardial VAs can be ablated at endocardial sites adjacent to the epicardial area septal to the lateral-LVS (septal-LVS). This study examined the prevalence and electrocardiographic and electrophysiological characteristics of septal-LVS VAs. We studied consecutive patients with idiopathic VAs originating from the LVS (67 patients) and aortic root (93 patients). Based on the ablation results, among 67 LVS VAs, 54 were classified as lateral and 13 as septal-LVS VAs. As compared with the lateral-LVS VAs, the septal-LVS VAs were characterized by a greater prevalence of left bundle branch block with left inferior-axis QRS pattern, later precordial transition, lower R-wave amplitude ratio in leads III to II, lower Q-wave amplitude ratio in leads aVL to aVR, and later local ventricular activation time relative to the QRS onset during VAs (V-QRS) in the great cardiac vein. The electrocardiographic and electrophysiological characteristics of the septal-LVS VAs were similar to those of the aortic root VAs. However, the V-QRS at the successful ablation site was significantly later during the septal-LVS VAs than aortic root VAs (p < .0001). The precordial transition was significantly later during the septal-LVS VAs than aortic root VAs (p < .05). Septal-LVS VAs are considered a distinct subgroup of idiopathic VAs originating from the left ventricular outflow tract.

Characteristics of Local Endograms at the Site of Successful Arrhythmia Suppression During Activation Mapping of Idiopathic Ventricular Arrhythmias Using 3D Navigation

A topical issue is the determination of the optimal values of activation time of local endograms (LE) and bipolar signal morphology during ablation in patients with idiopathic ventricular arrhythmias (VA) at the site of successful suppression, and the influence of 3D navigation on these values.&#x0D; The aim. To study earliest activation time (EAT) and LE morphology in the area of successful suppression during ablation of idiopathic VA using 3D navigation.&#x0D; Materials and methods. Analysis of the results of ablation in 57 patients with idiopathic VA was made. The patients were divided into two groups. Group I included 30 (52.6%) patients in whom mapping was performed using 3D navigation (EnSite Velocity Cardiac Mapping System). Group II included 27 (47.4%) patients who were mapped using conventional methods.&#x0D; In group I, extrasystole was found in 20 (66.7%) patients, while ventricular tachycardia was observed in 10 (33.3%) patients. In group II, extrasystole was revealed in 16 (59.3%) patients, and ventricular tachycardia in 11 (40.7%) patients.&#x0D; Group I included 21 (70%) patients with right ventricular localization of arrhythmia and 9 (30%) patients with left ventricular localization. Meanwhile, group II included 17 (63%) patients with a focus in the right ventricle and 10 (33%) patients with that in the left ventricle.&#x0D; The morphology of the LE was evaluated according to criteria such as polarity (positive or negative) and degree of signal fragmentation (monomorphic or fragmented). Polarity was determined by the initial direction of the signal during the first 10 ms, regardless of further changes in the endogram. The signal was considered fragmented if there were three or more polarity changes.&#x0D; Results. In group I, EAT of LE was -38.0±7.0 ms, while in group II it was -38.0±8.5 ms. No difference was found between the studied groups (p=0.834).&#x0D; Among all patients in both groups, the average value of EAT of LE at the site of successful arrhythmia elimination was -37.0±8.5 ms. In 92.9% cases EAT of LE was -30 ms or earlier. Only in four (7.1%) patients it was possible to achieve suppression of the arrhythmia with EAT of LE not earlier than -30 ms, while in all these cases the focus was always localized in the right ventricle. The minimum value of EAT of LE at the site of successful suppression of arrhythmia was -27 ms.&#x0D; The dominant morphology at the site of successful suppression among the patients in both groups, regardless of the type of mapping, was positive polarity of endogram.&#x0D; Conclusions. Regardless of the mapping method, in the site of successful idiopathic VA suppression LE must precede QRS by at least 27 ms.

Right ventricular scalloping index as cardiac magnetic resonance-derived marker for diagnosis of arrhythmogenic right ventricular cardiomyopathy.

The cardiac magnetic resonance (CMR) evaluation of right ventricular (RV) morphologic abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is subjective. Here, we aimed to use a quantitative index, the right ventricular scalloping index (RVSI), to standardize the measurement of RV free wall scalloping and aid in the imaging diagnosis. We retrospectively included 15 patients with definite ARVC and 45 age- and sex-matched patients with idiopathic right ventricular outflow tract ventricular arrhythmia (RVOT-VA) as controls. The RVSI was measured from cine images on four-chamber view to evaluate its ability to distinguish between ARVC and RVOT-VA patients. Other cardiac functional parameters including strain analysis were also performed. The RVSI was significantly higher in the ARVC than RVOT-VA group (1.56 ± 0.23 vs 1.30 ± 0.08, p < 0.001). The diagnostic performance of the RVSI was superior to the RV global longitudinal, circumferential, and radial strains, RV ejection fraction, and RV end-diastolic volume index. The RVSI demonstrated high intraobserver and interobserver reliability (intraclass correlation coefficient, 0.94 and 0.96, respectively). RVSI was a strong discriminator between ARVC and RVOT-VA patients (area under curve [AUC], 0.91; 95% CI, 0.82-0.99). A cutoff value of RVSI ≥1.49 provided an accuracy of 90.0%, specificity of 97.8%, sensitivity of 66.7%, positive predictive value (PPV) of 90.9%, and a negative predictive value (NPV) of 89.8%. In a multivariable analysis, a family history of ARVC or sudden cardiac death (odds ratio, 38.71; 95% CI, 1.48-1011.05; p = 0.028) and an RVSI ≥1.49 (odds ratio, 64.72; 95% CI, 4.58-914.63; p = 0.002) remained predictive of definite ARVC. RVSI is a quantitative method with good performance for the diagnosis of definite ARVC.

Intracardiac 3D navigation as a tool to improve the efficiency of ablation of idiopathic ventricular arrhythmias

Aim. Еvaluate the effect of 3D navigation on the effectiveness of ablation idiopathic ventricular arrhythmias. Materials and methods. The paper presents a retrospective postoperative analysis of 57 patients with idiopathic ventricular arrhythmias. Patients were divided into two groups. Group I included 30 (52.6 %) patients who used a 3D navigation system during mapping. Group II – 27 (47.4 %) patients in whom mapping was performed using classical methods. The effectiveness criteria were: frequency of acute suppression of arrhythmia, number of radiofrequency applications for suppression, and time of intervention. Results. Intraoperatively, complete suppression of the arrhythmia was successfully achieved in all cases in both groups. In group I average number of applications in patients with ventricular extrasystole was 5.5 (4.0; 8.0), while in group II – 6.5 (3,5; 9.0), without statistically significant difference (p = 0.414). A similar situation was observed with ventricular tachycardia. Іn group I number of applications was 3.2 (3.0; 4.3), and in group II – 5.0 (2.3; 11.0), which also had no statistically significant difference (р = 0.537). The duration of intervention for ventricular extrasystole in group I was 100.6 ± 26.6 min, while in group II – 136.4 ± 42.2 min, that has statistically significant difference (p = 0.007). During ablation of ventricular tachycardia in group I average duration was 89.3 ± 20.4 min, while in group II – 135.4 ± 55.5 min. The duration of intervention for ventricular tachycardia with the use of 3D navigation had a significantly shorter time compared to classical methods (p = 0.024). Conclusions. Based on the obtained data, we concluded that the use of 3D navigation significantly reduced the intervention time, regardless of the localization and type of arrhythmia. At the same time, no significant difference was found in the frequency of acute arrhythmia suppression and the number of applications to achieve the effect between the studied groups.

Outcomes of single-procedure radiofrequency catheter ablation for idiopathic ventricular arrhythmias: a single-centre retrospective cohort study

ObjectivesRadiofrequency catheter ablation is the first-line treatment for idiopathic premature ventricular complexes (PVCs) and ventricular tachycardias (VTs). However, the outcomes were less compared among the categories. The study aims to...

Predictors of unsuccessful radiofrequency catheter ablation of idiopathic ventricular arrhythmias in children

Ventricular arrhythmias (VAs) in children are generally idiopathic and have a benign course. Catheter ablation (CA) is increasingly becoming a first-line treatment option in children with idiopathic VAs. Acute ablation success reaches 100% procedures and long-term – 87%. Predictors of outcomes of CA in pediatric patients with idiopathic VAs have not been fully investigated.Aim: To identify predictors of long-term unsuccessful outcomes of CA in pediatric idiopathic VAs.Material and Methods. This retrospective study included 164 children aged 7 to 17 years with idiopathic VAs, who underwent CA from 2011 until 2023 in Almazov National Medical Research Centre. Efficiency was assessed in acute period and 6 months after CA.Results. In this study the acute success was 92% and long-term success was 88,4%. In multivariable models, multifocal VAs (odds ratio: 8,814; 95% CI: 1,943–39,981; p = 0,005), effectiveness of antiarrhythmic therapy (odds ratio: 16,522; 95%CI: 1,959–139,374; p = 0,010) and noninducibility of VAs during procedure (odds ratio: 9,369; 95% CI: 1,400–62,684; 0,021), become predictors of long-term unsuccessful outcomes of CA in pediatric idiopathic VAs.Conclusion. In our study there were identified independent predictors of long-term noneffective CA in children with idiopathic VAs, such as multifocal VAs, effectiveness of antiarrhythmic therapy, and noninducibility of VAs CA. In patients with presence of two or more ventricular foci and the effectivness of antiarrhythmic therapy, prolongate drug therapy may be more preferable.

Mid-term outcome of catheter ablation of idiopathic non-outflow tract ventricular arrhythmias

BackgroundCatheter ablation is recommended in patients with frequent and symptomatic ventricular arrhythmias (VAs) in an otherwise normal heart. Right or left outflow tract (OT) are the most common origins, and catheter ablation is highly effective with low complication rates. However, outcome of catheter ablation of VAs other than the OT (non-OTVAs) is limited. The aim of this single-center study was to assess the safety and mid-term outcome of catheter ablation for non-OTVAs.Method and ResultsFrom 2013 to 2018, 251 patients who underwent catheter ablation for idiopathic non-OTVAs were enrolled and grouped according to the origins including His-Purkinje system (HPS, n = 108), papillary muscle / moderator band (PM/MB, n = 47), tricuspid annulus (TA, n = 70), and mitral annulus (MA, n = 26), 244 (97.2%) had acute elimination of VAs. The time of VAs recurrence of the single procedure was 1.69 (0.12,9.72) months, with 66% occurring within the first 3 months. The recurrence rate was significantly higher in the PM/MB group than in the TA (p = 0.025) and MA groups (p = 0.023). The single procedure success rate in all patients was 70.1%, in which 66.7%, 59.6%, 80%, and 76.9% were achieved in the HPS, PM/MB, TA, and MA groups, respectively (p = 0.284). After multiple procedures, the total success rate was 76.5% at the follow-up of 4.38 ± 2.42 years. The rate was significantly lower in the PM/MB group than in the TA group (p = 0.035). In subgroup analysis, no significant difference was observed in the recurrence rate of single procedure in patients with different VA origins within the PM/MB (log-rank test, p = 0.546).ConclusionDespite a certain percentage of recurrences observed in the mid-term follow-up, catheter ablation remained feasible and effective for idiopathic non-OTVAs.

Localizing the Origin of Idiopathic Ventricular Arrhythmias From ECG Using a Recurrent Convolutional Neural Network With Attention

Localizing the Origin of Idiopathic Ventricular Arrhythmias From ECG Using a Recurrent Convolutional Neural Network With Attention

Clinical outcome of idiopathic juvenile ventricular arrhythmias in 25 dogs

Introduction/ObjectivesJuvenile ventricular arrhythmias in the absence of structural heart disease have been characterized in a small number of canine breeds with limited long-term follow up. The objective of this study was to describe the clinical outcome of dogs with JVA presenting to a university teaching hospital. Animals, materials, methodsTwenty five dogs, less than two years old with idiopathic ventricular arrhythmias were retrospectively identified via a medical record search. Young dogs with ventricular arrhythmias were excluded if they had structural heart disease, systemic illness, or an abnormal troponin (if performed). Electrocardiographic and Holter monitor data was evaluated for arrhythmia frequency and complexity at the time of diagnosis and over time. Long-term follow up was achieved through client and primary veterinarian contact. ResultsBreeds included German Shepherd (eight), Boxer (four), Great Dane (three), mixed breed (two) and one each of the following: Anatolian Shepherd, French Bulldog, golden retriever, Great Pyrenees, Labrador retriever, Shiloh Shepherd, miniature Poodle and Siberian Husky. The average age at diagnosis was 7.9 months (range, 2–22 months). The overall median survival was 10.96 years (range, 1.75–15.66 years). There was an average reduction in the number of ventricular beats by 86.7 % per year (P value −0.0257) based on Holter data. ConclusionIn most cases, idiopathic juvenile ventricular arrhythmias had a favorable long-term prognosis with reduced ectopy over time in this case series. Juvenile ventricular arrhythmias remains a diagnosis of exclusion but can be considered in a broader range of dog breeds than previously described.

Experience of left ventricular outflow tract arrhythmia ablation in paediatric patients using limited fluoroscopy and three-dimensional mapping technique.

The left ventricular outflow tract is an important source of ventricular arrhythmias. Up to one-third of all idiopathic ventricular arrhythmias in patients with structurally normal hearts may arise from this region. We would like to share the results of our left ventricular outflow tract ablation using three-dimensional mapping and limited fluoroscopy. This is a single-centre retrospective cohort study. Forty-six consecutive patients who underwent left ventricular outflow tract ablation procedures between January 2015 and June 2023 were included in the study. The EnSite Precision System (Abbott, St. Paul, MN, USA) was used to facilitate mapping and to reduce or eliminate the need for fluoroscopy. The study group comprised 29 males and 17 females, with a mean age of 13.4 ± 4.5 years. The most common location for arrhythmias was the left coronary cusp (n : 21). Other locations, in sequence, included the junction of the right and left coronary commissure (n : 10), right coronary cusp (n : 10), left ventricular outflow tract endocardium (n:4), aorto-mitral junction (n : 1), and great cardiac vein (n : 1). Nine of these patients had previously undergone unsuccessful right ventricular outflow tract ablation at another centre. Cryoablation was performed in three patients, irrigated radiofrequency ablation in three patients, and conventional radiofrequency ablation in the remaining patients. The acute success rate was 100%, and no recurrences were observed. The mean follow-up period was 49.6 ± 24.4 months. All patients were asymptomatic and were being followed without antiarrhythmic medication. Although left ventricular outflow tract ablations pose a risk for coronary artery and heart valve complications, they can be performed successfully and safely with the guidance of three-dimensional mapping.

The V6R/V5R index, a novel ECG criterion, can identify idiopathic ventricular arrhythmias arising from the aortic cusp

Abstract Background Idiopathic ventricular arrhythmias (VAs) with a left ventricular outflow tract (LVOT) origin often have dominant R waves (R wave amplitude&amp;gt;S wave amplitude) in the precordial leads (V1 through V6). Radiofrequency catheter ablation (RFCA) within the aortic cusp can eliminate LVOT-VAs. However, some require RFCA at the aorto-mitral continuity (AMC), the endocardium just below the LV summit, and/or mitral annulus for a cure. No ECG indices have been fully established to help differentiate between VAs that can be ablated from the aortic cusp and those that require ablation from other sites. Purpose The purpose of this study was to identify ECG indices useful in differentiating VAs with an aortic cusp origin from those from outside the cusp among the LVOT-VAs. Methods Among 200 patients in whom successful RFCA of idiopathic VAs was obtained at the OT, this study included 36 (totaling 37 premature ventricular complexes [PVCs]) who had dominant R waves in the precordial leads and an LVOT origin. According to the PVC origins, the PVCs were classified into 2 groups: 1) Cusp group (n=22); PVCs were successfully eliminated by RFCA within or just under the aortic cusp and 2) non-cusp group (n=15); PVCs were successfully ablated from the other LVOT sites described above or by a sequential unipolar ablation (combination of the cusp, AMC, and mitral annulus). The detailed PVC morphology was compared between the 2 groups. Results There was no significant difference in the ratio of the Q wave amplitude in aVL to aVR, V2 R/S amplitude ratio, V2 R/S duration index, V2 transition ratio, transition zone index, or V2S/V3R index between the 2 groups. However, the ratio of the R wave amplitude in V6 to V4 (V6R/V4R index) was significantly higher in the cusp group than in the non-cusp group (0.68±0.14 mV vs. 0.52±0.15 mV, p=0.002). The receiver operating characteristic curve demonstrated that a V6R/V4R index of &amp;gt;0.56 predicted the PVCs originated from the cusp with a sensitivity of 0.73 and specificity of 0.91 (area under the curve of 0.81). Conclusion The V6R/V4R index is a simple and useful ECG parameter and could distinguish PVCs with an aortic cusp origin from those originating from outside the cusp among the LVOT-VAs with a high accuracy.

Validation of a clinical model for predicting left versus right ventricular outflow tract origin of idiopathic ventricular arrhythmias.

Prediction of the chamber of origin in patients with outflow tract ventricular arrhythmias (OTVA) remains challenging. A clinical risk score based on age, sex and presence of hypertension was associated with a left ventricular outflow tract (LVOT) origin. We aimed to validate this clinical score to predict an LVOT origin in patients with OTVA. In a two-center observational cohort study, unselected patients undergoing catheter ablation (CA) for OTVA were enrolled. All procedures were performed using an electroanatomical mapping system. Successful ablation was defined as a ≥80% reduction of the initial overall PVC burden after 3 months of follow-up. Patients with unsuccessful ablation were excluded from this analysis. We included 187 consecutive patients with successful CA of idiopathic OTVA. Mean age was 52±15 years, 102 patients (55%) were female, and 74 (40%) suffered from hypertension. A LVOT origin was found in 64 patients (34%). A score incorporating age, sex and presence of hypertension reached 73% sensitivity and 67% specificity for a low (0-1) and high (2-3) score, to predict an LVOT origin. The combination of one ECG algorithm (V2 S/V3 R-index) with the clinical score resulted in a sensitivity and specificity of 81% and 70% for PVCs with R/S transition at V3 . The published clinical score yielded a lower sensitivity and specificity in our cohort. However, for PVCs with R/S transition at V3, the combination with an existing ECG algorithm can improve the predictability of LVOT origin.

Electrical and Structural Insights into Right Ventricular Outflow Tract Arrhythmogenesis.

The right ventricular outflow tract (RVOT) is the major origin of ventricular arrhythmias, including premature ventricular contractions, idiopathic ventricular arrhythmias, Brugada syndrome, torsade de pointes, long QT syndrome, and arrhythmogenic right ventricular cardiomyopathy. The RVOT has distinct developmental origins and cellular characteristics and a complex myocardial architecture with high shear wall stress, which may lead to its high vulnerability to arrhythmogenesis. RVOT myocytes are vulnerable to intracellular sodium and calcium overload due to calcium handling protein modulation, enhanced CaMKII activity, ryanodine receptor phosphorylation, and a higher cAMP level activated by predisposing factors or pathological conditions. A reduction in Cx43 and Scn5a expression may lead to electrical uncoupling in RVOT. The purpose of this review is to update the current understanding of the cellular and molecular mechanisms of RVOT arrhythmogenesis.

Anatomy of the Ventricular Outflow Tracts: An Electrophysiology Perspective.

Outflow tract ventricular arrhythmias are the most common type of idiopathic ventricular arrhythmia. A systematic understanding of the outflow tract anatomy improves procedural efficacy and enables electrophysiologists to anticipate and prevent complications. This review emphasizes the three-dimensional spatial relationships between the ventricular outflow tracts using seven anatomical principles. In turn, each principle is elaborated on from a clinical perspective relevant for the practicing electrophysiologist. The developmental anatomy of the outflow tracts is also discussed and reinforced with a clinical case.

Half versus normal saline irrigation during catheter ablation of outflow tract ventricular arrhythmias (HALF): a multi-center, parallel, open-label, randomized controlled study.

Animal studies demonstrated that deeper lesions could be achieved during radio-frequency catheter ablation (RFCA) by using half saline (HS) compared to normal saline (NS) as irrigation. This study sought to compare the efficiency and safety of HS and NS for irrigation during RFCA of idiopathic outflow tract ventricular arrhythmia (OT-VA). In this multicenter, randomized controlled study, 167 patients undergoing RFCA of OT-VA were randomized 1:1 to receive HS- or NS-irrigated ablation. Acute success was defined as the absence of induced targeted premature ventricular contraction (PVC) at the end of the procedure. The 6-month success was defined as a ≥ 80% reduction of pre-procedural PVC burden. There were no differences of baseline characteristics between the HS and NS group. Patients in HS group had shorter total ablation time (259.5 ± 155.5 S vs. 355.6 ± 230.7 S, P = 0.04) than that in NS group. The acute and 6-month success rates were similar between the HS and NS group (92.8 vs. 91.7%, P = 0.79; 90.9 vs. 92.1%, P = 0.79, respectively). No significant difference was observed in the incidence of steam pops between the HS and NS group (2.4 vs. 1.2%, P = 0.62). The ablation using HS irrigation achieved similar success rate and safety compared to that using NS irrigation but was associated with a shorter total ablation time. Chinese Clinical Trial Registry (ChiCTR2200059205).

Endocardial, epicardial, and right atrial approach for catheter ablation of premature ventricular contractions from the inferoseptal process of the left ventricle.

Inferoseptal process of the left ventricle (ISP-LV) might be a source of idiopathic ventricular arrhythmias. In these cases, ectopic foci are accessible from the LV endocardium, epicardially from the middle cardiac vein as well as from the right atrium (RA). This study reports a series of patients with premature ventricular contractions (PVCs) arising from the ISP-LV that were successfully ablated following access from different structures. Five patients (4 males, age 61 ± 12.8 years) with PVCs arising from the ISP-LV were successfully ablated using three different approaches for ablation-endocardial, epicardial (through coronary sinus or its branches), and RA approaches. Endocardial LV mapping, RA, and coronary sinus (CS) mapping were performed in all five cases. PVCs demonstrated RBBB or LBBB-like morphology and left superior axis. The three patients ablated endocardially had a maximum deflection index (MDI) of 0.36, 0.43, and 0.54, whereas in the remaining 2 patients, MDI was 0.57 and both demonstrated QS morphology in the inferior leads. Local activation time at the successful ablation site was 35 ± 8.9 (26-55) msec pre-QRS. Pacemapping at the successful ablation site resulted in a good (11/12) or perfect (12/12) QRS match in all cases. Three of the patients demonstrated frequent monomorphic PVCs of another morphology suggesting a remote exit site. All patients remained arrhythmia-free after a mean follow-up of 21 ± 15 (6-36) months. Successful ablation of PVCs from ISP-LV may require access from the CS or even RA apart from LV endocardial approach. Not infrequently patients demonstrate additional PVC foci.

PO-05-073 CHARACTERISTICS OF BIPOLAR AND UNIPOLAR ELECTROGRAMS AT SUCCESSFUL ABLATION TARGETS FOR VENTRICULAR ARRHYTHMIA ORIGINATING FROM THE VICINITY OF LEFT VENTRICULAR SUMMIT

Successful elimination of idiopathic ventricular arrhythmias from the vicinity of left ventricular summit could frequently be achieved from aortic cusps, endocardial or epicardial ablation. To explore whether the characteristics of bipolar and unipolar electrograms recorded from the vicinity of left ventricular summit could guide the appropriate site for successful ablation. Patients with idiopathic ventricular arrhythmias from the vicinity of left ventricular summit who underwent endocardial and epicardial mapping/ablation were retrospectively studied. Patients with structural heart disease or reentrant ventricular arrhythmias were excluded. Electrograms of the earliest activation sites in different anatomical structures, including great cardiac vein/anterior interventricular vein (GCV/AIV), supravalvular, subvalvular area, and/or right ventricular outflow tract (RVOT) were extracted for analysis. In total, 55 patients (median age 59 years, 42 men) and 163 mapping points were analyzed. These mapping points were located in GCV/AIV (n = 44), supravalvular area (n = 42), subvalvular area (n = 45), or the RVOT (n = 32). A pre-potential was identified at 17 (10.4%) points, while a unipolar QS morphology at 69 (42.3%) points. Successful ablation was achieved at 37 points. The presence of a pre-potential and the bipolar local activation time (LATBi) have a predictive value for successful ablation. In contrast, neither the unipolar LAT (LATUni), difference between LATBi and LATUni, presence of a unipolar QS morphology, nor the slope and interval of the unipolar descending limb could predict success. Earliest bipolar local activation and the presence of a pre-potential provide good surrogates to predict successful ablation of idiopathic ventricular arrhythmias originating from the vicinity of left ventricular summit.