Idiopathic Ventricular Arrhythmias Originating From the Aortic Root

Merging three-dimensional CT with electroanatomic mapping facilitates ablation of ventricular arrhythmias originating from aortic root and great cardiac vein

PURPOSE

In radiofrequency ablation near coronary arteries (CA), coronary angiography is traditionally recommended to estimate distance between catheter and CA. This study aimed to investigate the feasibility of an alternative approach for intuitively demonstrating spatial location of catheter and CA during ablation of ventricular arrhythmias (VAs) originating from aortic root (AR) and great cardiac vein (GCV).

METHODS

During mapping and ablation, 3D-reconstructed cardiac CT and electroanatomic mapping were merged, and distance between CA and catheter was monitored. Coronary angiography, for distance verification, was used when the distance was less than 5 mm in image integration model (IIM).

RESULTS

Twenty-three patients (52.26 ± 17.89 years, 12 men) with ablation originating in left cusp (LCC, n = 8), right cusp (n = 2), and left-right cusp junction (LCC-RCC, n = 12) and GCV (n = 1) were enrolled. In IIM, the distance between origin and CA was less than 5 mm in 2 VAs originating in LCC and one in GCV (3/23), whereas distance for ablation was always safe (12.3-22.3 mm) for VAs of LCC-RCC origin. IIM avoided angiography use in 20 patients, reducing radiation exposure by 80.6% (650.18 ± 624.31 vs 3356.97 ± 1529.46uGycm², P = 0.088). VA termination failed in two cases of LCC origin due to proximity to CA, and was achieved in all other patients (91.3%). No CA damage occurred during the procedures.

CONCLUSION

Mapping and ablation under IIM guidance of VAs of AR and GCV origin appears feasible and safe, while avoiding angiography use particularly in VAs of LCC-RCC origin.

Lesion Index Titration Using Contact-Force Technology Enables Safe and Effective Radiofrequency Lesion Creation at the Root of the Aorta and Pulmonary Artery

BACKGROUND

Ablation of some myocardial substrates requires catheter-based radiofrequency delivery at the root of a great artery. We studied the safety and efficacy parameters associated with catheter-based radiofrequency delivery at the root of the aorta and pulmonary artery.

METHODS

Thirty-six pigs underwent in-vivo catheter-based ablation under continuous contact-force and lesion index (power, contact-force, and time) monitoring during 60-s radiofrequency delivery with an open-irrigated tip catheter. Twenty-eight animals were allocated to groups receiving 40 W (n=9), 50 W (n=10), or 60 W (n=9) radiofrequency energy, and acute (n=22) and chronic (n=6) arterial wall damage was quantified by multiphoton microscopy in ex vivo samples. Adjacent myocardial lesions were quantified in parallel samples. The remaining 8 pigs were used to validate safety and efficacy parameters.

RESULTS

Acute collagen and elastin alterations were significantly associated with radiofrequency power, although chronic assessment revealed vascular wall recovery in lesions without steam pop. The main parameters associated with steam pops were median peak temperature >42°C and impedance falls >23 ohms. Unlike other parameters, lesion index values of 9.1 units (interquartile range, 8.7-9.8) were associated with the presence of adjacent myocardial lesions in both univariate ( P=0.03) and multivariate analyses ( P=0.049; odds ratio, 1.99; 95% CI, 1.02-3.98). In the validation group, lesion index values using 40 W over a range of contact-forces correlated with the size of radiofrequency lesions (R²=0.57; P=0.03), with no angiographic or histopathologic signs of coronary artery damage.

CONCLUSIONS

Lesion index values obtained during 40 W radiofrequency applications reliably monitor safe and effective lesion creation at the root of the great arteries.

Mapping and Ablation of Arrhythmias from Uncommon Sites (Aortic Cusp, Pulmonary Artery, and Left Ventricular Summit)

Despite advances in our understanding of the relevant anatomy and mapping and catheter ablation techniques of idiopathic outflow tract ventricular arrhythmias, challenging sites for catheter ablation remain the aortic cusps, pulmonary artery, and notably the left ventricular summit. A systematic approach should be used to direct mapping efforts efficiently between endocardial, coronary venous, and epicardial sites. Foci at the left ventricular summit, particularly intraseptal and at the inaccessible epicardial region, remain difficult to reach and when percutaneous techniques fail, surgical ablation remains an option but with risk of late coronary artery stenosis.

Twelve-lead electrocardiographic localization of idiopathic premature ventricular contraction origins

The major sites of origins of idiopathic ventricular arrhythmias have been elucidated. Idiopathic ventricular arrhythmias most often present as premature ventricular contractions (PVCs) with a focal mechanism, and commonly occur without structural heart disease. Idiopathic ventricular arrhythmias usually originate from specific anatomical structures, commonly endocardial but sometimes epicardial and exhibit characteristic electrocardiograms (ECGs) based on their anatomical background. There are general and specific ECG characteristics that can localize the site of idiopathic PVC origins. The general ECG characteristics include the bundle branch block pattern, axis, QRS polarity in lead V6, QRS duration, precordial transition, maximal deflection index, and so forth. They can roughly localize the site of idiopathic PVC origins. Several major sites of idiopathic PVC origins are located close to each other, and specific ECG characteristics are helpful for localizing the site of origins more accurately in those PVCs. Twelve-lead surface ECG algorithms usually can localize the site of idiopathic PVC origins with a high accuracy, but their accuracy can be limited by the patients' physique, heart rotation, specific conduction properties, presence of structural heart disease, and so forth. This review describes an overview of the approaches to the 12-lead surface ECG localization of idiopathic PVCs, and also discusses their caveats and limitations.

Special considerations in mapping and ablation of focal ventricular arrhythmias originating from the left ventricular outflow tract in patients with a transcatheter aortic valve replacement

Transcatheter aortic valve replacements (TAVRs) have been increasingly performed in high-risk patients with severe aortic stenosis. Focal ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) can occur after a TAVR, and radiofrequency catheter ablation (RFCA) should be considered as a treatment option when those VAs are drug-refractory. There are specific challenges in the RFCA of LVOT VAs after a TAVR because the tubular structure of the TAVR device sits in the LVOT. However, if the anatomical background of the TAVR and LVOT VAs are well understood and the anatomical relationship between the TAVR device and LVOT is sufficiently evaluated, RFCA of LVOT VAs in patients with a TAVR should be safe and highly successful.

Eccentric Activation Patterns in the Left Ventricular Outflow Tract during Idiopathic Ventricular Arrhythmias Originating From the Left Ventricular Summit

Background:

Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular summit (LVS) can be ablated from the great cardiac vein and remote endocardial sites. The ablation sites are determined by mapping in the great cardiac vein and left ventricular outflow tract. This study investigated whether that mapping could accurately predict the sites of LVS-VA origins.

Methods:

We studied 26 consecutive patients with idiopathic LVS-VA origins that were identified in the basal and apical LVS in 15 and 11 patients, respectively.

Results:

Radiofrequency catheter ablation of the apical LVS-VAs was successful in the great cardiac vein in 9 patients and in the apical LV outflow tract in 2. That of the basal LVS-VAs was successful in the aortomitral continuity in 9 patients, at the junction of the left and right coronary cusps in 4, and in the left coronary cusp in 2. Three apical LVS-VAs exhibited an eccentric endocardial activation pattern that was from the basal to apical LV outflow tract. In 11 basal LVS-VAs, the activation pattern was eccentric because the ventricular activation within the great cardiac vein in the apical LVS was earlier than that in the basal LV outflow tract. In 2 basal LVS-VAs, the activation pattern was eccentric because a relatively early ventricular activation was recorded at multiple sites away from the successful ablation site.

Conclusions:

Eccentric activation patterns often occurred during idiopathic LVS-VAs, which could mislead the catheter ablation of those VAs. Understanding such eccentric activation patterns was suggested to be able to improve the outcomes of the catheter ablation of those VAs by the anatomic approach.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Long-term mode and timing of premature ventricular complex recurrence following successful catheter ablation

PURPOSE

Catheter ablation of premature ventricular contractions (PVCs) is highly successful and has become the hallmark treatment for symptomatic or highly prevalent cases. However, few studies exist that evaluate the outcomes of ablation and likely mechanisms of PVC recurrence beyond 1 year of follow-up.

METHODS

This study is a retrospective analysis of patients who underwent catheter ablation for symptomatic PVCs with acute procedural success and had clinical follow-up ≥ 12 months.

RESULTS

Forty-four patients (24 women; age 53.5 ± 4.8 years) following acutely successful PVC ablation with long-term follow-up were studied. At a mean of 36 ± 6 months, overall long-term ablation success was 75% (33/44 patients). Notably, recurrence of the targeted PVC focus was low (6.8%, 3/44 patients); the majority of recurrences were from a new source location (18.2%, 8/44 patients). The time course for targeted versus de novo PVC recurrences was significantly different: recurrence of a PVC similar to the targeted PVC morphology occurred at a mean of 5.0 ± 2.0 months, while recurrence of a PVC different from the index case occurred at a mean of 35.8 ± 17.1 months (p = 0.01). Non-ischemic cardiomyopathy was associated with increased risk of PVC recurrence (odds ratio [OR] 14.50 (95% confidence interval [CI] 1.92-109.33, p = 0.01)) and was a significant negative prognostic factor in multivariate analysis for PVC recurrence survival (hazard ratio [HR] 4.63, 95% CI 1.03-20.74, p = 0.04).

CONCLUSIONS

The majority of long-term PVC recurrences occur late in follow-up, at locations remote from the targeted PVC source or sources. Such sites may represent ongoing substrate evolution; additional work is required to determine the precise substrate alterations which promote such arrhythmogenic changes.

Novel method for the prediction of para-Hisian premature ventricular complexes from the electrocardiogram

BACKGROUND

Catheter ablation of para-Hisian (PH) premature ventricular complexes (PVCs) has a high risk of heart block. This study aimed to find the electrocardiographic (ECG) predictors of PH-PVCs.

METHODS

We enrolled 47 patients who underwent an electrophysiologic study for catheter ablation of PVCs and analyzed the ECG characteristics, retrospectively.

RESULTS

The PVC locations were the PH in 14, right ventricular (RV) outflow tract (OT) in 11, left ventricular (LV) OT in 16, LV septum in 5, and LV summit in 1. The QRS width of the PH-PVCs was significantly narrower than that of the rest of PVCs (140.9 ± 17.1 ms vs. 158.9 ± 19.4 ms, P = 0.004). Precordial transition of the PH-PVCs related to sinus rhythm was not helpful in predicting the location. Lead I had monophasic R waves in 100% and lead aVR QS waves in 100%. In aVL, 13 of 14 patients had monophasic R waves, and 1 had biphasic (rS) waves with an initial positive polarity. Among the study cohort, 15 patients had a QS in aVR and R in aVL, including 13 PH-PVCs and 2 PVCs coming from the RVOT septum and LVOT septum, respectively. The QS in aVR and monophasic R in aVL had a sensitivity of 92.8%, specificity of 93.9%, positive predictive value of 86.7%, and negative predictive value of 96.9% for localizing PH-PVCs.

CONCLUSIONS

A PVC morphology with a QS in aVR and monophasic R in aVL and QRS width <143 msec, could be used as a reliable parameter for predicting the PH location.

Ablation of ventricular arrhythmias with predominant monophasic "R" waves in precordial leads from the left sinus of Valsalva: Electrocardiographic and electrophysiologic characteristics

BACKGROUND

While the left sinus of Valsalva (LSV) is a frequent origin of ventricular arrhythmias (VAs). Uncommonly, VAs with right bundle branch block (RBBB) morphology may be successfully terminated from the LSV.

OBJECTIVE

We aimed to investigate the electrocardiographic and electrophysiologic characteristics of VAs with RBBB which were successfully eliminated from the LSV.

METHODS

We identified patients with VAs successfully ablated from the LSV from January 2014 to December 2017 and compared electrophysiologic characteristics and ablation sites of those VAs with RBBB versus a control group of patients with left bundle branch block morphology.

RESULTS

We identified 18 patients with RBBB and predominant "R" waves in the precordial leads. In 12 (66.7%) patients, a small "s" wave in lead V2 and positive "R" in the remaining pericardial leads could be seen. Overall, a single "V" potential was seen in 72.2% of patients in the study group, while discrete potentials were recorded in 80% of the patients in the control group. The majority (88.9%) of the VAs could only be terminated at the nadir of the LSV in the study group. After mean follow-up of 33 ± 14 months, 93.8% and 92% were free of VAs after initial ablation in study and control group, respectively (P = 0.99).

CONCLUSION

Some VAs with predominant monophasic "R" wave in precordial leads could be terminated from LSV, especially a small "s" wave in lead V2 was recorded. The nadir of LSV is highly successful for RBBB VAs and single electrogram was recorded at the target for most of the cases.

Low power ablation for left coronary cusp ventricular tachycardia-Efficacy and long-term outcome

Background

The left coronary cusp is an uncommon but well-known site for the ablation of idiopathic ventricular tachycardia (VT). Proximity to the left coronary ostium makes ablation of this arrhythmia challenging. Different power settings have been described by various operators. Our objective was to describe the outcomes with low power ablation.

Methods

Once mapping confirmed origin from the left coronary cusp, ablation was performed if the best site was situated at least 5 mm from the left coronary ostium. Ablation was started at 15 W and, if successful, was stopped after 30 s. When required, higher powers were used up to 30 W.

Results

Ten patients with VT or premature ventricular beats mapped to the left coronary cusp were included in the study. No ablation was performed in one patient because of proximity to the left coronary ostium. Successful ablation was performed in eight of the other nine patients with a mean power of 18.1 ± 5.3 W and duration of 42.2 ± 13.5 s. There were no complications. All the eight patients remained free of recurrence at 16.8 ± 16.5 months of follow-up.

Conclusions

VT can be ablated from the left coronary cusp close to the left coronary ostium. Ablation with low power is effective in achieving immediate success which is also durable with time while avoiding complications.

Image integration into 3-dimensional-electro-anatomical mapping system facilitates safe ablation of ventricular arrhythmias originating from the aortic root and its vicinity

Aims

During ablation in the vicinity of the coronary arteries establishing a safe distance from the catheter tip to the relevant vessels is mandatory and usually assessed by fluoroscopy alone. The aim of the study was to investigate the feasibility of an image integration module (IIM) for continuous monitoring of the distance of the ablation catheter tip to the main coronary arteries during ablation of ventricular arrhythmias (VA) originating in the sinus of valsalva (SOV) and the left ventricular summit part of which can be reached via the great cardiac vein (GCV).

Methods and results

Of 129 patients undergoing mapping for outflow tract arrhythmias from June 2014 till October 2015, a total of 39 patients (52.4 ± 18.1 years, 17 female) had a source of origin in the SOV or the left ventricular summit. Radiofrequency (RF) ablation was performed when a distance of at least 5 mm could be demonstrated with IIM. A safe distance in at least one angiographic plane could be demonstrated in all patients with a source of origin in the SOV, whereas this was not possible in 50% of patients with earliest activation in the summit area. However, using the IIM a safe position at an adjacent site within the GCV could be obtained in three of these cases and successful RF ablation performed safely without any complications. Ablation was successful in 100% of patients with an origin in the SOV, whereas VAs originating from the left ventricular summit could be abolished completely in only 60% of cases.

Conclusion

Image integration combining electroanatomical mapping and fluoroscopy allows assessment of the safety of a potential ablation site by continuous real-time monitoring of the spatial relations of the catheter tip to the coronary vessels prior to RF application. It aids ablation in anatomically complex regions like the SOV or the ventricular summit providing biplane angiograms merged into the three-dimensional electroanatomical map.

A case of ventricular ectopy eliminated by catheter ablation: Diversity of the potentials on the left coronary cusp

An 18-year-old man without organic heart disease underwent catheter ablation for frequent monomorphic ventricular ectopic beats(VEBs). The origin of the VEB was presumed located on the left coronary cusp(LCC) regarding his electrocardiography. Local activation in the right ventricular outflow tract was not so early. On the LCC, four different prepotentials were obtained by slight relocation of the catheter. Finally, on the site with positive discrete prepotential recorded on the distal electrodes, an application of radiofrequency current immediately eliminated the VEB. Although LCC is considered as a small structure, detailed mapping may be important to find the most optimal ablation site.

Idiopathic Ventricular Premature Contraction and Ventricular Tachycardia: Distribution of the Origin, Diagnostic Algorithm, and Catheter Ablation

Idiopathic ventricular premature contractions (VPCs), defined as VPCs in the absence of obvious structural heart disease, are one of the common types of arrhythmia in clinical practice. They are sometimes complicated with non-sustained ventricular tachycardia (VT), and/or sustained VT with almost same QRS morphology in 12 leads ECG. Idiopathic VT (IVT) commonly occurs by focal mechanisms and the origins are distributed in a variety of sites in both ventricles. In this article, the clinical characteristics of IVT/IVPCs, the diagnostic algorithm, and how to ablate them will be reviewed.

Insights on the pulmonary artery-derived ventricular arrhythmia

Pulmonary artery-derived ventricular arrhythmia is gradually being recognized, which in a clinical context is recognized as an arterial ectopic beat. Our study aimed to provide new insights on the epidemiological characteristics, origin site, electrocardiogram (ECG) characteristics, intracardiac electrophysiological characteristics and radiofrequency catheter ablation (RFCA) strategies for pulmonary artery-derived ventricular arrhythmia. Patients with a distance between the origin site and the pulmonary valve of >10 mm have what is known as pulmonary trunk-derived ventricular arrhythmia, while patients with a distance between the origin site and the pulmonary valve of ≤10 mm have what is known as pulmonary sinus cusp-derived ventricular arrhythmia. It is very difficult to differentiate pulmonary artery-derived ventricular arrhythmia from right ventricular outflow tract-derived ventricular arrhythmia on ECGs as both share similar anatomical features, but pulmonary artery-derived ventricular arrhythmia shows obvious intracardiac electrophysiological characteristics. Currently, conclusions based on the epidemiological characteristics of pulmonary artery-derived ventricular arrhythmia, relationship between the origin site and the pulmonary valve, electrophysiological characteristics, and RFCA strategies are controversial and still need further study.

Left atrial appendage as a vantage point for mapping and ablating premature ventricular contractions originating in the epicardial left ventricular summit

Idiopathic ventricular tachycardia arising from the LV summit epicardial area can be successfully mapped and possibly ablated from the left atrial appendage.

Successful elimination of premature ventricular contractions by ablation of origin and preferential pathway

However, the common strategy for eliminating premature ventricular contractions (PVCs) is to explore the exit site and ablate, which may be difficult in some cases. The origin and the preferential pathway, an insulated pathway connected to the exit, may also become targets for eliminating PVCs.

Novel electrophysiological criteria for septal ventricular outflow tract tachycardias requiring a sequential bilateral ablation

BACKGROUND

Septal ventricular outflow tract ventricular arrhythmias (OT-VAs) are defined as septal origin VAs from the right ventricular or left ventricular OT. Patients with septal OT-VAs may require a sequential bilateral OT ablation. This study aimed to evaluate the electrophysiological characteristics and ablation outcome in patients with septal OT-VAs.

METHODS

We retrospectively analyzed the electrocardiography and electrophysiological parameters in 96 patients (mean age 49 ± 15 years, 49 male) undergoing bilateral activation mapping before catheter ablation of idiopathic septal OT-VAs. The patients were categorized into three groups based on the successful ablation sites, including the right ventricular outflow tract (RVOT), RVOT/left ventricular outflow tract (LVOT), and LVOT.

RESULTS

Mapping in the three groups demonstrated a gradually decreasing and increasing trend in the earliest activation time obtained from the RVOT and LVOT, respectively. The absolute earliest activation time discrepancy (AEAD) of ≤18 milliseconds could predict the requirement for a sequential bilateral ablation with a sensitivity and specificity of 100.0% and 93.7%, respectively. The small AEAD (≤21 milliseconds) was associated with a higher recurrence rate in patients receiving a successful unilateral ablation, while patients with a longer distance between the bilateral OT earliest activation sites (DEA > 26 mm) increased future recurrences after an initially successful sequential bilateral ablation.

CONCLUSIONS

The application of bilateral OT-VA activation mapping and the measurement of the AEAD and DEA provided not only pivotal information for the ablation strategy, but also prognostic implications for recurrences in patients with septal OT-VAs.

Idiopathic Ventricular Arrhythmias Originating From the Parietal Band

Backgrounds—

The parietal band is one of the muscle bands in the right ventricle. This study investigated the electrocardiographic and electrophysiological characteristics and ablation outcome of idiopathic ventricular arrhythmias (VAs) originating from the parietal band.

Methods and Results—

We studied 14 patients with idiopathic VA origins in the parietal band among 294 consecutive patients with VA origins in the right ventricle. The QRS morphologies of the parietal band VAs were characterized by a left bundle branch block and left inferior (n=12) or superior (n=2) axis pattern with the presence of a notch in the middle of the QRS in all cases, precordial transition at ≤lead V3 in 7 patients, and a slow QRS onset in 4 patients. During parietal band VAs, a far-field ventricular electrogram with an early activation was always recorded in the His bundle region, regardless of the location of the VA origins. During the catheter ablation, a mean number of 10.4±7.4 radiofrequency applications with a duration of 1099±1034 seconds were delivered. Catheter ablation was successful in 10 patients, and VAs recurred in 4 during a mean follow-up period of 41±24 months. A change in the QRS morphology was observed spontaneously in 4 patients, immediately after the ablation in 4, and at the time of a VA recurrence in 2.

Conclusions—

Idiopathic VAs rarely originated from the parietal band. The catheter ablation of the parietal band VAs was always challenging, requiring a large amount of the radiofrequency energy delivery for a successful ablation with a relatively high recurrence rate.

Approach selection of radiofrequency catheter ablation for ventricular arrhythmias originating from the left ventricular summit: potential relevance of Pseudo Delta wave, Intrinsicoid deflection time, maximal deflection index

BACKGROUND

Ventricular arrhythmias (VAs) originating from the left ventricular summit is a challenge for radiofrequency catheter ablation (RFCA). The present study aimed to investigate the appropriate RFCA strategy for VAs originating from the left ventricular summit.

METHODS

Forty-five consecutive patients with VAs arising from the left ventricular summit were successfully ablated at our cardiac electrophysiology center and reviewed in the study.

RESULTS

Thirty-two cases of VAs were eliminated in the left ventricular endocardium by retrograde transaortic (n = 22, 22/45, 48.9%) or antegrade transseptal (n = 10, 10/45, 22.2%) approaches, the other 13 cases were eliminated in the left ventricular epicardium by distal great cardiac vein (DGCV) approach (n = 13, 13/45, 28.9%). Though these VAs were similar in electrocardiographic (ECG) morphology, the pseudo delta waves (PDW), intrinsicoid deflection time (IDT), maximal deflection index (MDI) differed among them, PDW >53 ms, IDT > 74 ms, MDI > 0.45 strongly indicated that ablating left ventricular summit VAs by DGCV approach. During mean follow-up of 19.5 ± 13.2 (range, 3-60) months, 2 (4.4%) patients experienced VAs recurrence.

CONCLUSION

This retrospective study showed that VAs of left ventricular summit origin can be effectively cured with RFCA. For these VAs, prolonged PdW, IDT, MDI indicating RFCA by DGCV approach can be attempted firstly.

Efficacy of an Anatomical Approach in Radiofrequency Catheter Ablation of Idiopathic Ventricular Arrhythmias Originating From the Left Ventricular Outflow Tract

Background—

When anatomic obstacles preclude radiofrequency catheter ablation of idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT), an alternative approach from the anatomically opposite side (endocardial versus epicardial or above versus below the aortic valve) may be considered (anatomic ablation). The purpose of this study was to investigate the efficacy of an anatomic ablation in idiopathic LVOT VAs.

Methods and Results—

We studied 229 consecutive patients with idiopathic LVOT VAs. Radiofrequency ablation from the first suitable site was successful in 190 patients, and in the remaining 39 patients, it was unsuccessful or had to be abandoned because of anatomic obstacles. In 22 of these 39 patients, an anatomic ablation was successful, and the VA origins were located in the intramural LVOT in 17 patients, basal left ventricular summit in 4, and LVOT septum near the His bundle in 1. The anatomic ablation was highly successful for idiopathic VAs originating from the intramural LVOT (>75%) and lateral LVOT, whereas it was unlikely to be successful for idiopathic VAs originating from the basal left ventricular summit (25%) and sepal LVOT.

Conclusions—

When a standard catheter ablation targeting the best electrophysiological measure of idiopathic LVOT VAs was unsuccessful or had to be abandoned because of anatomic obstacles, an anatomic ablation was moderately successful. These idiopathic LVOT VAs with a successful anatomic ablation commonly arose from the intramural LVOT among the left coronary cusp, aortomitral continuity, and epicardium, occasionally the basal left ventricular summit, and rarely the LVOT septum near the His bundle.

Disappearance of Idiopathic Outflow Tract Premature Ventricular Contractions After Catheter Ablation of Overt Accessory Pathways

BACKGROUND

Multiple mechanisms have been proposed for idiopathic premature ventricular contractions (PVCs) originating from the outflow tracts (OTs). Recent observations such as the coexistence of these arrhythmias with atrioventricular nodal reentrant tachycardias and the association between discrete prepotentials and successful ablation sites of ventricular arrhythmias (VAs) from the OTs suggest a common link.

OBJECTIVE

In this case series we draw attention to a unique association between accessory pathways (APs) and idiopathic PVCs from the OTs, disappearing after AP ablation.

METHODS

We identified 6 cases in collaboration with several international electrophysiology centers, which presented with pre-excitation in association with OT, and in 1 case inflow tract (IT), PVCs on 12-lead surface ECG.

RESULTS

Six cases displayed pre-excitation and PVCs, in 5 cases originating from the right ventricular outflow tract (RVOT) and in 1 case from the right ventricular inflow tract (RVIT). In all patients, PVCs were monomorphic and had fixed coupling intervals, in 3 cases presenting in bigeminy. Catheter ablation of the AP led to the simultaneous disappearance of PVCs in 5 of 6 cases. The sites of ablation were remote from the OTs in all these cases. In most cases, the occurrence of OT PVCs was closely associated with the presence of pre-excitation.

CONCLUSION

The coexistence of pre-excitation and PVCs from the OTs and the fact that in 5 of 6 cases PVCs disappeared after AP ablation suggests a common mechanism for arrhythmia genesis.

Outflow Tract Premature Ventricular Contractions and Ventricular Tachycardia: The Typical and the Challenging

The ventricular outflow tracts are the most common sites of origin for ventricular arrhythmias that occur in the absence of structural heart disease. Drug therapy with β-blockers and calcium blockers has limited efficacy for control. In the presence of marked symptoms or frequent arrhythmia causing left ventricular (LV) dysfunction, catheter ablation is a consideration. The right ventricular outflow tract, aortic root, LV outflow endocardium, and epicardium are potential sites for ablation for these arrhythmias. In intractable cases of highly symptomatic ventricular arrhythmias originating from the LV summit, surgical ablation is an option.

Prevalence and Electrocardiographic and Electrophysiological Characteristics of Idiopathic Ventricular Arrhythmias Originating From Intramural Foci in the Left Ventricular Outflow Tract

Backgrounds—

Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) sometimes require catheter ablation from both the endocardial and epicardial sides for their elimination, suggesting the presence of intramural VA foci. This study investigated the prevalence and electrocardiographic and electrophysiological characteristics of these idiopathic intramural LVOT VAs when compared with the idiopathic endocardial and epicardial LVOT VAs.

Methods and Results—

We studied 82 consecutive VAs with origins in the aortomitral continuity (n=30), LV summit (n=34), and intramural site (n=18). The maximum deflection index (the time to the maximum deflection in the precordial leads/QRS duration) was the largest in LV summit VAs (0.52±0.07), smallest in aortomitral continuity VAs (0.45±0.06), and midrange in intramural VAs (0.49±0.05). The electrocardiographic and electrophysiological characteristics of the intramural LVOT VAs were similar to those of the aortomitral continuity VAs. The intramural LVOT VAs exhibited a significantly smaller R-wave amplitude ratio in leads III to II, and ratio of the Q-wave amplitude in leads aVL to aVR, and a significantly earlier and later local ventricular activation time relative to the QRS onset at the His bundle and successful ablation sites than the LV summit VAs, respectively.

Conclusions—

Intramural sites account for a significant proportion of LVOT VAs. The electrocardiographic and electrophysiological characteristics of the idiopathic intramural LVOT VAs were midrange between those of the idiopathic endocardial and epicardial LVOT VAs, and more similar to those of the idiopathic endocardial LVOT VAs than those of the idiopathic epicardial LVOT VAs.

Long-Term Results After Single and Multiple Procedures of Ablation of Ventricular Tachycardia

INTRODUCTION

The aim of this study was to assess long-term results after single and multiple procedures of catheter ablation of ventricular tachycardia (VT). While it is generally accepted that multiple procedures are sometimes necessary in order to achieve long-term clinical success, the literature on this issue displays wide variability.

METHODS

We assessed the outcome of 160 consecutive patients who underwent 214 ablation procedures in the period 2008 to May 2015: 93 had overt structural heart disease (SHD) (previous myocardial infarction in 74 cases) and 67 had no SHD.

RESULTS

After the first procedure, the 1-year actuarial recurrence rates were 25% in patients with SHD and 5% in those without. However, recurrences increased progressively after the first year, reaching 46% and 35%, respectively, at 5 years. Overall, VT recurred in 35/93 (38%) patients with SHD and 22/67 (33%) patients without. Redo (1 to 4) procedures were performed in 28 (20%) patients with SHD and 18 (27%) patients without. After the last procedure, the 1-year actuarial recurrence rates were 5% in patients with SHD and 7% in those without, and the corresponding rates at 5 years were 23% and 7%. During follow-up, 21 patients died (all in the SHD group): no death was related to VT recurrence.

CONCLUSIONS

During long-term follow-up, VT frequently recurs after the first procedure, both in patients with SHD and in those without; multiple procedures are needed in order to increase the success rate.

Ablation of ventricular arrhythmia originating from the aortic sinus of Valsalva in an adolescent with anomalous origin of the right coronary artery

A 16-year-old patient underwent successful ablation of ventricular arrhythmia originating from the aortic sinus of Valsalva following surgical unroofing of an anomalous right coronary artery. This case illustrates the complexity of decision making in the management of patients with anomalous coronary arteries and the importance of keeping an open mind when determining ventricular arrhythmia aetiology and origin.

Catheter Ablation of Idiopathic Ventricular Arrhythmias Arising From the Cardiac Outflow Tracts - Recent Insights and Techniques for the Successful Treatment of Common and Challenging Cases

Ventricular arrhythmias (VA), like premature ventricular contractions (PVC) and ventricular tachycardia (VT) in patients without structural heart disease (idiopathic VA), mainly arise from the right and left ventricular outflow tracts (RVOT/LVOT). The prognosis for OT VA is generally good in the majority of patients, but there is potential for developing dilated cardiomyopathies from the high burden of VA, as well as a certain risk for sudden cardiac death because of fast monomorphic VT or polymorphic VT triggered by short-coupling PVC. Radiofrequency catheter ablation (RFCA) has evolved into a widely accepted treatment strategy for patients suffering from VAs. A detailed knowledge of surface ECGs and complex cardiac anatomy, especially within the ventricular OTs, is essential for the understanding of cardiac OT-VAs and highly related to safe and successful RFCA procedures. This review article focuses on RFCA of idiopathic VA arising from the cardiac OT as well as adjacent regions and will illustrate recent insights and technical issues. (Circ J 2016; 80: 1073-1086).

The "Dead-End Tract" and Its Role in Arrhythmogenesis

Idiopathic outflow tract ventricular arrhythmias (VAs) represent a significant proportion of all VAs. The mechanism is thought to be catecholamine-mediated delayed after depolarizations and triggered activity, although other etiologies should be considered. In the adult cardiac conduction system it has been demonstrated that sometimes an embryonic branch, the so-called "dead-end tract", persists beyond the bifurcation of the right and left bundle branch (LBB). Several findings suggest an involvement of this tract in idiopathic VAs (IVAs). The aim of this review is to summarize our current knowledge and the possible clinical significance of this tract.