Left Atrial Tachycardia Originating From the Mitral Annulus–Aorta Junction

A novel endocardial activation-derived predictor for focal paraseptal atrial tachycardias: evidence from a multicenter cohort study

BACKGROUND

The electrocardiogram-based algorithm for predicting para-septal atrial tachycardia (PSAT) is limited by the significant overlaps in the P-wave morphology originating from various para-septal sites.

OBJECTIVE

The aim of this study was to investigate the endocardial activation characteristics of PSAT and to seek an endocardial activation-derived predictor for the ablation site.

METHODS

Forty-four patients (11 males, average 62.6±14.7 years) with PSAT ablation in four tertiary medical centers were assigned into three groups according to the ablation site: right atrial (RA) para-Hisian region (Group 1, n=10), the noncoronary cusp (NCC) (Group 2, n=13) and left atrial (LA) para-septal areas (Group 3, n=21). Multiple-chamber activation mapping was performed guided by a 3D navigation system. The discrepancies in the earliest activation time between two of three chambers (ΔRA-LA, ΔRA-NCC and ΔLA-NCC) were calculated in each group and used for pairwise comparisons.

RESULTS

There was significant difference in ΔRA-LA, ΔRA-NCC, and ΔLA-NCC compared among three groups. ΔRA-LA was the only parameter which could consistently predict the ablation site of PSAT with good accuracy (AUC 1.000, sensitivity 100%/ specificity 100%, and cut-off value 7ms for predicting right para-Hisian or NCC ablation; AUC 0.974, sensitivity 92.3%/specificity 95.2%, and cut-off value -4 ms for predicting NCC or left para-septal ablation). Based on two cut-off values, A two-step algorithm was developed to predict the ablation site of PSAT with positive predictive value of 95.4% and negative predictive value of 97.0%.

CONCLUSIONS

ΔRA-LA is a useful endocardial activation-derived parameter for predicting the successful ablation site of PSAT.

Focal atrial tachycardias originating from the aorta-mitral continuity: Anatomical and electrophysiological characteristics

BACKGROUND

The aorta-mitral annulus conjunction (AMC) is an uncommon site of origin of focal atrial tachycardias (ATs). Hence, the electrophysiological and ablation target characteristics are poorly described.

OBJECTIVE

The purpose of this study was to describe the characteristics of AMC AT in detail.

METHODS

The study enrolled 650 patients with AT, 21 (3.2%) of whom had AT originating from the AMC. A comprehensive evaluation, including electrocardiography, electrophysiology study, computed tomography scan, and intracardiac echocardiography, was performed.

RESULTS

The majority (90.5%) of ATs occurred spontaneously. The mean age of this group was 48.9 ± 21.6 years, with 12 being female (57.1%). Seventeen patients had a typical biphasic P wave with a prominent positive component. The earliest activation site in the right atrium was near the His bundle, with average activation -10.3 ± 6.0 ms preceding the P wave. The successful ablation targets were distributed as follows: 1 case at 9 o'clock, 6 cases at 10 o'clock, 7 cases at 11 o'clock, 6 cases at 12 o'clock, and 1 case in the left coronary cusp. The local AMC potential differed from the commonly perceived annular potential and was characterized by a large A and a small V (atrial-to-ventricular ratio > 1). The angle of encroachment on the left atrial anterior wall, compressed by the left coronary cusp, was significantly smaller in the AMC AT group than in the control group, which may have contributed to the arrhythmia substrate (141.7° ± 11.5° vs 155.2° ± 13.9°; P = .026).

CONCLUSION

A new strategy for mapping AMC ATs has been introduced. The ablation target should have an atrial-to-ventricular ratio of >1.

Ablation of ectopic atrial foci for successful management of symptomatic bradycardia: A case series (bradycardia and ectopic atrial beats)

Atrial premature contractions (PACs) that block at the atrio-ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing.

Inter-atrial epicardial muscular fibers as a possible source of atrial tachyarrhythmias

A 22-year-old woman without structural heart disease underwent catheter ablation of frequent premature atrial contractions (PACs). Radiofrequency applications from both the right and left atrium were effective in suppressing or eliminating these PACs. The distance between the right atrial ablation site and the successful ablation site at the right-sided pulmonary venous carina measured 18 mm on the CARTO map, and no cardiac structure, i.e. the inter-atrial septum, was present between those sites. Taken together, the epicardial muscular fibers in the inter-atrial groove were considered to play a role as an arrhythmogenic source of this atrial tachyarrhythmia.

Learning objective

Epicardial muscular fibers connecting the right atrium and right-sided pulmonary venous carina are known to preclude isolation of the veins. This epicardial connection in the interatrial groove can be an arrhythmogenic source or part of a reentrant circuit of atrial tachyarrhythmias.

Endocardial ablation at the mitral valve vestibule and its surroundings for the treatment of arrhythmias linked to the greater cardiac vasculature

BACKGROUND

The role of the epicardial vasculature in supraventricular and ventricular arrhythmias was described in clinical studies as well as its treatment by intravascular point ablation or alcohol injection. We report on a case series of patients with different arrhythmias linked to an epicardial site of origin with evidence supporting transmural extensions that were targeted for ablation with successful outcomes.

METHODS

The records of patients who has catheter ablation for Supraventricular or Ventricular arrhythmias between 2015-2020 was searched for patients with (1) arrhythmias linked to the epicardial vasculature and (2) findings to support an endocardial connection to the epicardial vasculature by activation mapping, pace mapping, or differential pacing, and (3) were successfully ablated via an endocardial approach only.

RESULTS

From the data searched, we identified 5 patients with the following arrhythmias left ventricular summit ectopy, peri-mitral atrial flutter, preexcitation with inducible atrioventricular reentry tachycardia (AVRT) and a concealed left side accessory pathway with inducible AVRT that were linked to the following vessels: Great Cardiac vein, persistent left superior vena cava, left coronary cusp and left ventricular outflow tract. Endocardial connections were supported by a combination of electro anatomical activation mapping, pace-mapping, and differential pacing. Endocardial ablations performed in all patients were successful without complications CONCLUSION: : This report highlights a subset of patients with arrhythmias linked to the greater cardiac vascular system that can be safely and effectively ablated endocardially, given the limitations and possible complications of epicardial ablation within or in the proximity of the epicardial vasculature. This article is protected by copyright. All rights reserved.

New Discovery of Left Atrial Macroreentry Tachycardia: Originating from the Spontaneous Scarring of Left Atrial Anterior Wall

AIMS

This study sought to describe left atrial macroreentry tachycardia (LAMRT) originating from the spontaneous scarring of left atrial anterior wall (LAAW) and its clinical and electrophysiological characteristics, mechanisms, and the formation of substrates.

METHODS AND RESULTS

9 of 123 patients (89% female, age 79.78 ± 5.59 years) had LAMRT originating from the LAAW with no cardiac surgery or prior left atrial (LA) ablation. The mean tachycardia cycle length (TCL) was 241.67 ± 38.00 milliseconds. Spontaneous scars areas and low voltage areas (LVAs) in the LAAW were found in all patients. Successful ablation of the critical isthmus caused termination of the LAMRT and was not inducible in all patients. Arrhythmogenic substrates of LAMRT were the spontaneous scars of LAAW, which matched with the aorta or/and pulmonary artery contact area. The area under the curve (AUC) of age and combination of gender and age for predicting the LAMRT originating from the LAAW were 0.918 and 0.951, respectively, with a cutoff value of ≥73.5 years of age and gender (female) predicting LAMRT with 88.9% sensitivity and 89% specificity.

CONCLUSION

Combination of gender and age provides a simple and useful criterion to distinguish LAMRT from cavotricuspid isthmus- (CTI-) dependent atrial tachycardia in macroreentry atrial tachycardia (MRAT) in patients without a history of surgery or ablation. Aorta or/and pulmonary artery contacting LA may be related to spontaneous scars. Ablation the isthmus eliminated LAMRT in all patients.

Comparison of strategies for catheter ablation of focal atrial tachycardia originating near the His bundle region

BACKGROUND

Recent studies have suggested that para-Hisian atrial tachycardia (AT) can be successfully ablated from the right atrium (RA), left atrium (LA), or noncoronary cusp (NCC) in the aorta; however, the best approach remains unclear.

OBJECTIVE

This study aimed to compare different approaches to radiofrequency catheter ablation (RFCA) of para-Hisian AT.

METHODS

We retrospectively analyzed 68 consecutive patients (49[72%] women; mean age 61 ± 13 years) treated with RFCA for this type of AT. Mapping of the RA (n = 68), LA (n = 21), and NCC (n = 52) was performed during AT to identify the earliest activation site and to apply RFCA.

RESULTS

RFCA successfully terminated AT in the RA in 13 of 28 patients (46.4%), in the LA in 4 of 16 patients (25.0%), and in the NCC in 46 of 52 patients (88.5%) after 1 procedure (P < .05). Atrioventricular block occurred only during RFCA in the RA in 4 of 28 patients (14.3%). After a mean follow-up of 33.5 ± 25.4 months, AT recurrence was observed in 5 of 13 patients (38.5%) ablated in the RA, 1 of 4 (25.0%) ablated in the LA, and 2 of 46 (4.4%) ablated in the NCC (P < .05). RFCA in the LA was effective only if the local activation time (LAT) was earlier than that in the RA. RFCA in the NCC was successful regardless of the LAT (P < .05).

CONCLUSION

Mapping and ablation in the NCC should be always considered in cases of AT originating from the His bundle region, regardless of the LAT.

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.

Incessant Long R-P Tachycardia

A 13-year-old boy had a positive P wave in V1 with a negative P wave in lead I, aVL, and aVR, as well as a positive P wave in the inferior leads, which correlated with a left atrial appendage (LAA) atrial tachycardia (AT) focus. P-wave morphologies can provide clues regarding an AT's origin, and this P-wave negative in lead I favored LAA AT. Careful mapping along the atria and coronary sinus to determine the earliest site of activation for the surface P wave is a reliable method for precisely localizing the AT origin as a target for catheter ablation.

Usefulness of combined CARTO electroanatomical mapping and manifest entrainment in ablating adenosine triphosphate-sensitive atrial tachycardia originating from the atrioventricular node vicinity

Background

By using a noncontact mapping system, adenosine triphosphate (ATP)-sensitive atrial tachycardia (ATP-AT) originating from the atrioventricular (AV) node vicinity was successfully ablated at the entrance to the slow conduction zone indicated by the manifest entrainment technique. We aimed to prospectively validate the efficacy of the combination of CARTO electroanatomical mapping and manifest entrainment in ablating this ATP-AT.

Methods

Of the 27 AT patients from January 2013 to March 2014, 6 patients with sustained ATP-AT were studied (age, 67±13 years; tachycardia cycle length, 350±95 ms). We first created the CARTO map during AT, and performed rapid pacing from the anterior right atrial wall (ARAW) and cavotricuspid isthmus (CTI) approximately 30 mm remote from the earliest activation site (EAS). We identified the site where manifest entrainment, defined as the orthodromic capture of the EAS with a long conduction time, was observed, and ablated the site approximately 20 mm remote from the EAS, between the pacing site and the EAS.

Results

Manifest entrainment was demonstrated in all patients paced from the ARAW (four patients) and from the CTI (two patients). Ablation at the prespecified site terminated AT in 6±3 s, and AT became no longer inducible in all patients. At the successful ablation sites, discrete atrial electrograms were recorded; however, low-amplitude, fractionated electrograms suggestive of slow conduction were not observed in all patients. The atrio-His interval during sinus rhythm remained unchanged (from 96±12 to 89±7 ms, p=NS). During 11±6 months, no patients showed AT recurrence and AV conduction abnormality.

Conclusion

CARTO mapping- and manifest entrainment-guided ablation strategy is effective and safe in the treatment of ATP-AT.

Focal atrial tachycardia originating from the septal mitral annulus: electrocardiographic and electrophysiological characteristics and radiofrequency ablation

AIMS

This study sought to investigate electrocardiographic characteristics, electrophysiological features, and radiofrequency ablation in patients with focal atrial tachycardia (AT) originating from the septal mitral annulus.

METHODS AND RESULTS

In 13 patients with AT originating from the septal mitral annulus, activation mapping was performed to identify the earliest activation site. Successful ablation was performed through either a transseptal (n = 12) or a retrograde aortic approach (n = 1). As confirmed by electrogram recordings, fluoroscopy, and three-dimensional (3D) mapping, successful ablation sites were located in the anterior paraseptal, mid- to anteroseptal, and posterior septal mitral annulus in eight, three, and two patients, respectively. Foci for all locations demonstrated a negative/positive appearance in lead V1. Mapping in the right atrium demonstrated that the earliest right atrial activation was near the septum (His-bundle region or proximal coronary sinus). The electrograms at the successful ablation sites were fractionated in 9 patients, and presented with an atrial:ventricular ratio of <1 in all 13 patients. There were no complications in any patients and long-term success was achieved in 12 of 13 patients during the 23 ± 6 months following ablation.

CONCLUSION

The area surrounding the septal mitral annulus, most commonly the anterior paraseptal, is an unusual, but important site of origin for focal AT, which is associated with a distinctive P-wave morphology and atrial endocardial activation sequence. Radiofrequency ablation of AT originating from the septal mitral annulus, through either a transseptal or a retrograde aortic approach appears to be safe and effective.

Atrial tachycardias arising from the atrial appendages and aortic sinus of valsalva

Focal atrial tachycardias arising from the atrial appendages and the aortic sinuses of Valsalva are less frequently encountered in clinical practice. This review article describes the clinical presentation, surface P wave morphology, electrophysiologic characteristics and treatment of these arrhythmias. Catheter ablation of these focal tachycardias has a high success rate. It is however important to be aware of specific anatomic considerations in these locations for optimal treatment outcomes with low complication rates.

Focal atrial tachycardia surrounding the anterior septum: strategy for mapping and catheter ablation

Background—

Focal atrial tachycardias (ATs) surrounding the anterior atrial septum (AAS) have been successfully ablated from the right atrial septum (RAS), the aortic cusps, and the aortic mitral junction. However, the strategy for mapping and ablation of AAS-ATs has not been well defined.

Methods and Results—

Of 227 consecutive patients with AT, 47 (20.7%; mean age, 56.3±11.6 years) with AAS-ATs were studied; among them, initial ablation was successful at RAS in only 5 of 14 patients and at noncoronary cusp (NCC) in 28 of 33 patients. In 45 of the 47 patients, the 46 of 48 AAS-ATs were eliminated at RAS in 8 patients, NCC in 35 patients (earliest activation time at NCC was later than that at RAS by 5–10 ms in 6 patients), and aortic mitral junction in 3 patients (all with negative P wave in lead aVL and positive P wave in the inferior leads), including 1 patient whose 2 ATs were eliminated separately from the NCC and the aortic mitral junction.

Conclusions—

Most of the ATs surrounding the AAS can be eliminated from within the NCC, which is usually the preferential ablation site. Ablation at the RAS and aortic mitral junction should be considered when supported by P-wave morphologies on surface ECG and results of activation mapping and ablation.

Arrhythmias in the developing heart

Prevalence of cardiac arrhythmias increases gradually with age; however, specific rhythm disturbances can appear even prior to birth and markedly affect foetal development. Relatively little is known about these disorders, chiefly because of their relative rarity and difficulty in diagnosis. In this review, we cover the most common forms found in human pathology, specifically congenital heart block, pre-excitation, extrasystoles and long QT syndrome. In addition, we cover pertinent literature data from prenatal animal models, providing a glimpse into pathogenesis of arrhythmias and possible strategies for treatment.

Electrophysiologic characteristics of ventricular arrhythmias arising from the aortic mitral continuity-potential role of the conduction system

INTRODUCTION

Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown.

METHODS

Procedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate.

RESULTS

Of the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs; 26.1 ± 10.9% vs. 14.9 ± 10.1%, P = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 milliseconds vs. 33.1 ± 8.8 milliseconds, P = 0.03), lower pace map scores (8.7 ± 1.6 vs. 11.4 ± 0.8, P = 0.001), and a trend toward shorter V-H intervals during VA (32.1 ± 38.6 milliseconds vs. 76.3 ± 11.1 milliseconds, P = 0.06) as compared to those without PP. A strong and positive correlation was found between V-H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R(2) = 0.97, t = 13.7, P < 0.001) but not in those without PPs.

CONCLUSION

Local EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success.

Left septal atrial tachycardias: electrocardiographic and electrophysiologic characterization of a paraseptal focus

OBJECTIVE

The objective was to characterize the electrocardiographic and electrophysiological features of focal atrial tachycardia (FAT) originating from the left septum (LS).

BACKGROUND

FAT is recognized to occur at predefined anatomic locations rather than randomly throughout the atria. We describe the ECG and EP features of ATs originating from the LS as an important site for apparent perinodal tachycardias.

METHODS

Nine patients presenting with LS FAT from a consecutive series of 384 underwent EP/RFA for symptomatic FAT.

RESULTS

The mean age was 56 ± 12 years; 7 female with symptoms for 36 ± 28 months. P wave morphology (PWM) was negative/positive in lead V1 and across the precordial leads and negative or negative/positive in inferior leads in all patients. Tachycardia was incessant in 6 out of 9 patients with a mean tachycardia cycle length 421 ± 56 milliseconds. His A was ahead of P wave in all patients (mean -15 ± 5 milliseconds) and earlier than CS proximal (mean 4 ± 9 milliseconds). Successful acute focal ablation achieved at a mean of 31 ± 12 milliseconds ahead of P wave with no recurrences at a mean follow-up of 30 ± 28 months.

CONCLUSION

Although the left septum is an uncommon site for focal AT an awareness of this location for harboring foci is particularly important when mapping apparently right-sided septal tachycardias.

Electrophysiological characteristics of focal atrial tachycardia surrounding the aortic coronary cusps

BACKGROUND

Catheter ablation of atrial tachycardia (AT) arising near the coronary cusps has been reported in limited numbers of patients. We investigated the electrophysiological characteristics of these ATs in 22 consecutive patients.

METHODS AND RESULTS

This study included 22 patients (mean age ± SD, 53 ± 11 years; 86% female) with ATs arising near the aortic coronary cusps who underwent successful ablation. Activation mapping was performed during tachycardia to identify the earliest activation site. All patients achieved successful ablation through either a retrograde aortic (n=19) or a transseptal (n=3) approach. The successful ablation sites were located in the noncoronary cusp (NCC) (n=16), including 3 near the junction between the NCC and right coronary cusp. The remaining 6 cases were ablated from the left coronary cusp (LCC) (n=3) or the left atrium posterior to the LCC (n=3). For most tachycardias, there were distinctive P-wave morphological features recorded for each cusp location. Furthermore, analysis of the electrogram morphological features recorded during tachycardia at successful ablation sites revealed an atrial/ventricular (A/V) ratio >1 in 14 of 16 NCC ATs; the remaining 2, from the NCC near the junction with the right coronary cusp, showed an A/V ratio ≤ 1. At ablation sites in the LCC, the A/V ratio was <1 (4 of 6 patients) or 1 (remaining 2 patients). During a follow-up duration of 30 ± 13 months, all patients were free of arrhythmias without antiarrhythmic drugs.

CONCLUSIONS

ATs surrounding the aortic coronary cusps can be safely and effectively ablated, with good long-term outcomes. In addition to the P-wave morphological features, the A/V ratio of the local electrogram recording during tachycardia facilitated the localization of successful sites.

Paroxysmal Long R-P Tachycardia

This case highlights characteristic features of atrial tachycardia arising from the mitral annulus. P wave morphologies can provide additional clues regarding the origin of atrial tachycardia on the mitral annulus. The atrial activation sequence is sometimes, but not always, earliest in the His potential electrogram position and may or may not be characterized by proximal-to-distal coronary sinus activation. Careful mapping along the mitral annulus to determine the earliest site of activation with reference to the surface P wave is a reliable method for precisely localizing an atrial tachycardia origin. Catheter ablation can be approached using either a transseptal or retrograde aortic approach.

Focal atrial tachycardia arising from the right atrial appendage: electrophysiologic and electrocardiographic characteristics and catheter ablation

BACKGROUND

Focal atrial tachycardia (AT) arising from the crista terminalis, pulmonary veins, para-Hisian region, tricuspid annulus and coronary sinus ostium regions are well described. Less information exists regarding AT arising from the right atrial appendage (RAA).

OBJECTIVE

The study was done to characterise the electrocardiographic and electrophysiologic features and radiofrequency ablation (RFA) of focal AT arising from the RAA.

METHODS

Six patients of a consecutive series of 250 patients undergoing RFA for focal AT are reported. Mapping was performed during tachycardia or frequent atrial ectopy to identify the earliest activation in the atria. Atrial appendage angiography was performed to identify the origin in the RAA after RFA.

RESULTS

All the six (2.4%) patients (four women; mean age 26 +/- 11 years) had tachycardia originating from RAA. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. P-wave morphology was upright in I, II, III and aVF, inverted in aVR, inverted or isoelectric in aVL. Lead V1 showed a negative component and lead V4-V6 showed an upright component in all the patients. The earliest endocardial activity occurred at the high right atria in all the patients. The earliest endocardial activation at the successful RFA site occurred 48 +/- 18 ms before the onset of the P wave. RFA was highly successful in all the six patients. Long-term success was achieved in six of the six patients over a mean follow-up of 24 +/- 5 months.

CONCLUSIONS

The RAA is an uncommon site of origin for focal AT 2.4%. There is consistent P-wave morphology and endocardial activation associated with this type of AT. Using mapping targeted to anatomic structures achieved a high success rate for ablation. Irrigated-tip catheter may be helpful for patients who had a recurrence.

An unusual case of permanent junctional reciprocating tachycardia: Successful ablation at the mitral annulus-aorta junction

A 25-year-old woman with drug-refractory permanent junctional reciprocating tachycardia (PJRT) and a previous failed ablation, was referred to our institution. Electrophysiological study confirmed the diagnosis of orthodromic atrioventricular reentry tachycardia using a slowly conducting accessory pathway. This accessory pathway was successfully ablated by conventional radiofrequency at the left anteroseptal region using a transseptal approach. Catheter ablation of this accessory pathway (Coumel type) at the mitral annulus-aorta junction offers insights on a rare anatomical location of PJRT.

Catheter ablation within the sinus of Valsalva--a safe and effective approach for treatment of atrial and ventricular tachycardias

BACKGROUND

Ablation of the aortic sinus of Valsalva in adults for ectopic atrial tachycardia (EAT) and ventricular tachycardia (VT)/premature ventricular complexes (PVCs) has been reported in only a very few patients. Limited data exist concerning the safety of aortic ablation.

OBJECTIVE

The purpose of this study was to confirm aortic wall and aortic valve integrity after ablation and to evaluate for potential cerebral embolism due to thrombus formation at aortic wall lesions.

METHODS

From January 2006 to August 2007, 21 patients with EAT (n = 6) or VT/PVCs (n = 15) originating from the sinus of Valsalva underwent successful ablation. The aortic wall structure was evaluated using transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) the day after ablation and at 6-month follow-up for all patients. To rule out cerebral embolism due to postablation thromboembolic events, a cerebral MRI was performed immediately after ablation in six patients and at 6-month follow-up in all patients. Ablation success was defined by 24-hour Holter monitoring before hospital discharge and after 6 months.

RESULTS

Aortic wall integrity was confirmed in all patients by TEE and MRI. Cerebral MRI showed evidence of silent cerebral ischemia in one patient. Aortic valve thickening was detected in one patient by TEE.

CONCLUSION

Ablation in the aortic sinus of Valsalva is a safe and effective approach for atrial tachycardia or VT/PVCs. The incidence of silent ischemia needs further evaluation.

Focal Atrial Tachycardia Originating from the Left Atrial Appendage: Electrocardiographic and Electrophysiologic Characterization and Long-Term Outcomes of Radiofrequency Ablation

INTRODUCTION

This study sought to investigate electrophysiologic characteristics and radiofrequency ablation (RFA) in patients with focal atrial tachycardia (AT) arising from the left atrial appendage (LAA).

METHODS

This study included seven patients undergoing RFA with focal AT. Activation mapping was performed during tachycardia to identify an earlier activation in the left atria and the LAA. The atrial appendage angiography was performed to identify the origin in the LAA before and after RFA.

RESULTS

AT occurred spontaneously or was induced by isoproterenol infusion rather than programmed extrastimulation and burst atrial pacing in any patient. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P wave was highly positive in inferior leads in all patients. Lead V1 showed upright or biphasic (+/-) component in all patients. Lead V2-V6 showed an isoelectric component in five patients or an upright component with low amplitude (<0.1 mV) in two patients. Earliest endocardial activity occurred at the distal coronary sinus (CS) ahead of P wave in all seven patients. Mean tachycardia cycle length was 381 +/- 34 msec and the earliest endocardial activation at the successful RFA site occurred 42.3 +/- 9.6 msec before the onset of P wave. RFA was acutely successful in all seven patients. Long-term success was achieved in seven of the seven over a mean follow-up of 24 +/- 5 months.

CONCLUSIONS

The LAA is an uncommon site of origin for focal AT (3%). There were consistent P-wave morphology and endocardial activation associated with this type of AT. The LAA focal ablation is safe and effective. Long-term success was achieved with focal ablation in all patients.

Complex genomic rearrangement in CCS-LacZ transgenic mice

The cardiac conduction system (CCS)-lacZ insertional mouse mutant strain genetically labels the developing and mature CCS. This pattern of expression is presumed to reflect the site of transgene integration rather than regulatory elements within the transgene proper. We sought to characterize the genomic structure of the integration locus and identify nearby gene(s) that might potentially confer the observed CCS-specific transcription. We found rearrangement of chromosome 7 between regions D1 and E1 with altered transcription of multiple genes in the D1 region. Several lines of evidence suggested that regulatory elements from at least one gene, Slco3A1, influenced CCS-restricted reporter gene expression. In embryonic hearts, Slco3A1 was expressed in a spatial pattern similar to the CCS-lacZ transgene and was similarly neuregulin-responsive. At later stages, however, expression patterns of the transgene and Slco3A1 diverged, suggesting that the Slco3A1 locus may be necessary, but not sufficient to confer CCS-specific transgene expression in the CCS-lacZ line.

Successful catheter ablation of focal atrial tachycardia from the non-coronary aortic cusp

We describe a patient with frequent episodes of unusual paroxysmal supraventricular tachycardia. During the electrophysiological examination, the tachycardia was easily induced and terminated by atrial pacing. The earliest activation during right atrial activation mapping was located near the atrioventricular node and the His bundle. However, detailed mapping of the aortic root demonstrated that the local activation in the non-coronary aortic cusp preceded the activation at the His bundle region. Radiofrequency catheter ablation at this site terminated the tachycardia with no complications.

Successful catheter ablation of focal left atrial tachycardia originating from the mitral annulus aorta junction

Focal left atrial tachycardias (AT) originating from the mitral annulus-aorta (MA-Ao) junction are rare and their mechanisms are unclear. We report a 35-year-old male with successful ablation of an exercise-induced focal AT due to triggered activity originating from the MA-Ao junction. The AT occurred spontaneously during treadmill exercise testing and was easily induced by an atrial extrastimulus and atrial burst pacing after intravenous administration of isoproterenol. The AT was terminated by an atrial extrastimulus as well as a bolus of 5 mg of adenosine 5'-triphosphate. The coupling intervals of the extrastimuli that induced the AT were positively correlated with the interval between the extrastimuli and the first beat of the AT, suggesting the triggered activity as a tachycardia mechanism. The AT was successfully eliminated by a focal ablation at the MA-Ao junction with the earliest atrial activation where fractionated atrial potentials were recorded. The MA-Ao junction should be recognized as an important arrhythmogenic region.