Radiofrequency ablation for treatment of primary atrial tachycardias

Demonstration of the Anatomical Tachycardia Circuit in Sinoatrial Node Reentrant Tachycardia: Analysis Using the Entrainment Method

Background

The anatomical tachycardia circuit of sinoatrial node reentrant tachycardia (SANRT) has not been well clarified. This study aimed to elucidate the tachycardia circuit of SANRT.

Methods and Results

Exit and entrance of the intranodal sinoatrial node conduction (I‐SANC) of the reentry circuit were identified in 15 SANRT patients. After identifying the earliest atrial activation site (EAAS) during the tachycardia (EAAS‐SANRT), rapid atrial pacing was delivered from multiple atrial sites to identify the entrainment pacing site where manifest entrainment and orthodromic capture of the EAAS‐SANRT were demonstrated. Radiofrequency energy was then delivered starting at a site 2 cm proximal to the EAAS‐SANRT in the direction of the entrainment pacing site and gradually advanced toward the EAAS‐SANRT until tachycardia termination to localize the I‐SANC entrance. The EAAS‐SANRT was orthodromically captured by pacing delivered from the distal coronary sinus (n=7), high posteroseptal right atrium (n=2), low posteroseptal right atrium (n=2), low anterolateral right atrium (n=2), or coronary sinus ostium (n=2). Radiofrequency energy delivery to the entrance of the I‐SANC, 10.4±2.8 mm away from the EAAS‐SANRT, terminated tachycardia immediately after onset of energy delivery (3.4±2.3 seconds). The successful ablation site was located further from the EAAS during sinus rhythm (EAAS‐sinus) than the EAAS‐SANRT (12.8±4.5 versus 7.2±3.1 mm; P<0.0001).

Conclusions

The reentry circuit of SANRT was composed of the entrance and exit of the I‐SANC being located at distinctly different anatomical sites. SANRT was eliminated by radiofrequency energy delivered to the I‐SANC entrance, which was further from the EAAS‐sinus than I‐SANC exit.

Focal atrial tachycardia ablation: Highly successful with conventional mapping

BACKGROUND/OBJECTIVE

Radiofrequency catheter ablation (RFCA) of focal atrial tachycardia (FAT) traditionally is guided by conventional endocardial mapping of earliest atrial activation; however, more recently electro-anatomical mapping is heralded as a more effective, albeit more expensive, tool to guide ablation. Herein we present the results of conventional mapping-guided RFCA. Apropos, we conducted a literature search of studies reporting > 10 FAT patients submitted to RFCA.

METHODS AND RESULTS

Conventional mapping-guided RFCA, performed in 63 FAT patients (aged 42.4 + 17.3 years; 14 with incessant tachycardia and 12 with tachycardiomyopathy (TCM)), was successful in 61 (96.8%) patients, applied for single foci in 59 (93.7%) and two foci in 4 patients, right (n = 46) or left sided (n = 17). The earliest atrial activation time at the ablation site was 41.3 ± 16.2 ms. Fluoroscopy time averaged 27.3 + 18.7 min, and procedure lasted 2.6 + 1.7 h. Complications occurred in two patients (sinus pauses in one needing a pacemaker and a large inguinal hematoma in one). Over 29.0 + 22.9 months, four patients (6.5%) had recurrences, of whom three were successfully re-ablated. All patients with TCM showed gradual improvement to normalization over 4-6 months. Literature search showed that RFCA success is equally high when guided with either conventional (88.5%) or electro-anatomical mapping (90%) with similar recurrences (9.6% vs. 9.5%).

CONCLUSION

Conventional mapping-guided RFCA of FAT had high success (96.8%) with low complication (3.2%) and recurrence rates (6.5%). TCM was fully reversible. These results are comparable to those achieved with the more expensive electro-anatomical mapping, which may be reserved for more complex cases or for those failing the conventional approach.

Epicardial ablation of tachyarrhythmia in children: Experience at two academic centers

BACKGROUND

Experience with percutaneous epicardial ablation of tachyarrhythmia in pediatrics is limited. This case series addresses the feasibility, safety, and complications of the procedure in children.

METHODS

A total of nine patients underwent 10 epicardial ablation procedures from 2002 to 2013 at two academic centers. Activation mapping was performed in all cases, and electroanatomic map was utilized in nine of the 10 procedures. Patients had undergone one to three failed endocardial catheter ablations in addition to medical management, and all had symptoms, a high-risk accessory pathway (AP), aborted cardiac arrest with Wolff-Parkinson-White syndrome (WPW), or ventricular dysfunction. A standard epicardial approach was used for access in all cases, using a 7- or 8- Fr sheath. Epicardial ablation modality was radiofrequency (RF) in seven, cryoablation (CRYO) in one, and CRYO plus RF in one.

RESULTS

Median age was 14 (range 8-19) years.

INDICATIONS

drug refractory ectopic atrial tachycardia (one), ventricular tachycardia (VT) (five), high-risk AP (two), and aborted cardiac arrest from WPW - (one). Epicardial ablation was not performed in one case despite access due to an inability to maneuver the catheter around a former pericardial scar. VT foci included the right ventricular outflow tract septum, high posterior left ventricle (LV), LV outflow tract, postero-basal LV, and scar from previous rhabdomyoma surgery. WPW foci were in the area of the posterior septum and coronary sinus in all three cases. Overall procedural success was 70% (7/10), with epicardial ablation success in five and endocardial ablation success after epicardial mapping in two. The VT focus was close to the left anterior descending coronary artery in one of the unsuccessful cases in which both RF and CRYO were used. There was one recurrence after a successful epicardial VT ablation, which was managed with a second successful epicardial procedure. There were no other recurrences at more than 1 year of follow-up. Complications were minimal, with one case of inadvertent pleural access requiring no specific therapy. No pericarditis or effusion was seen in any of the patients who underwent epicardial ablation.

CONCLUSION

Epicardial ablation in pediatric patients can be performed with low complications and acceptable success. It can be considered for a spectrum of tachycardia mechanisms after failed endocardial ablation attempts and suspected epicardial foci. Success and recurrence may be related to foci in proximity to the epicardial coronaries, pericardial scar, or a distant location from the closest epicardial location. Repeat procedures may be necessary.

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 tachycardia originating from the aortomitral junction

Atrial tachycardia (AT) originating from the aortomitral junction is a very rare and challenging disease. Its arrhythmic characteristics have not been described in detail compared with the descriptions of the arrhythmic characteristics of AT originating from the other locations. Only a few case reports have documented successful ablation of this type of AT using transaortic or transseptal approaches. We describe a case with AT that was resistant to right-sided ablation near the His bundle failed and transaortic ablation at the aortomitral junction successfully eliminated.

The potential role of nonpharmacologic electrophysiology-based interventions in improving outcomes in patients hospitalized for heart failure

Hospitalization for heart failure (HHF) is commonly associated with symptomatic improvement in response to standard medical therapy, yet there remains a substantial risk of rehospitalization and death. Clinically stable outpatients and decompensated inpatients represent two types of patients with chronic heart failure. In the former, treatment of common heart rhythm disorders with nonpharmacologic electrophysiology-based interventions is of substantial benefit in select patients. The potential benefits of these interventions in the hospitalized setting are not well studied. In this review, current knowledge is discussed and future research directions are suggested with nonpharmacologic electrophysiology-based interventions to reduce the morbidity and mortality associated with patients with HHF.

Utility of Atrial and Ventricular Cycle Length Variability in Determining the Mechanism of Paroxysmal Supraventricular Tachycardia

INTRODUCTION

No prior studies have systematically investigated the diagnostic value of cycle length (CL) variability in differentiating the mechanism of paroxysmal supraventricular tachycardia (PSVT).

METHODS AND RESULTS

We studied 173 consecutive patients with PSVT; 86 typical atrioventricular nodal reentrant tachycardia (AVNRT), 11 atypical AVNRT, 47 orthodromic reciprocating tachycardia (ORT), and 29 with atrial tachycardia (AT). Two consecutive atrial cycles that displayed the most CL variability were selected for analysis. One hundred and twenty-six patients (73%) had > or = 15 msec variability in tachycardia CL. The change in atrial CL predicted the change in subsequent ventricular CL in six of eight patients (75%) with atypical AVNRT, 18 of 21 patients (86%) with AT, in none of 66 patients with typical AVNRT, and in 32 patients with ORT. The change in atrial CL was predicted by the change in preceding ventricular CL in 55 of 66 patients (83%) with typical AVNRT, no patient with atypical AVNRT, 27 of 31 patients (87%) with ORT, and one of 21 patients (5%) with AT. The sensitivity, specificity, and positive and negative predictive values of a change in atrial CL predicting the change in ventricular CL for AT or atypical AVNRT were 83%, 100%, 100%, and 95%, respectively. The corresponding values for the change in atrial CL being predicted by the change in the preceding ventricular CL for typical AVNRT or ORT were 85%, 97%, 99%, and 65%, respectively.

CONCLUSION

Tachycardia CL variability > or = 15 msec is common in PSVT. A change in atrial CL that predicts the change in subsequent ventricular CL strongly favors AT or atypical AVNRT. A change in atrial CL that is predicted by the change in the preceding ventricular CL favors typical AVNRT or ORT.

The Results of Radiofrequency Catheter Ablation of Supraventricular Tachycardia in Children

BACKGROUND

Radiofrequency (RF) catheter ablation represents a major advance in the management of children with cardiac arrhythmias and has rapidly become the standard of care for the first-ling therapy of supraventricular tachycardias (SVTs). The purpose of this study was to investigate the results of the RF catheter ablation of SVTs in pediatric patients.

METHODS

From December 1989 to August 2005, a total of 228 pediatric patients (age: 9 +/- 7 years, range: 5-18 years; male:female = 117:111) with clinically documented SVT underwent an electrophysiologic study and RF catheter ablation at our institution.

RESULTS

The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 140, 61%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 66, 29%), atrial tachycardia (AT; n = 11, 5%), and atrial flutter (AFL; n = 11, 5%). The success rate of the RF catheter ablation was 92% for AVRT, 97% for AVNRT, 82% for AT, and 91% for AFL, respectively. Procedure-related complications were infrequent (8.7%; major complications: high grade AV block (2/231, 0.9%); minor complications: first degree AV block (6/231, 2.6%), reversible brachial plexus injury (2/231, 0.9%), and local hematomas or bruises (10/231, 4.3%)). The recurrence rate was 4.7% (10/212) during a follow-up period of 86 +/- 38 months (0.5-185 months).

CONCLUSIONS

The RF catheter ablation was a safe and effective method to manage children with paroxysmal and incessant tachycardia. The substrates of the arrhythmias differed between the pediatric and adult patients. However, the success rate of the ablation, complications, and recurrence during childhood were similar to those of adults.

Atrial tachycardia with slow pathway conduction mimicking typical atrioventricular nodal reentrant tachycardia

A 68-year-old woman with palpitations underwent electrophysiologic testing. During burst atrial pacing the PR interval exceeded the RR interval and induced a supraventricular tachycardia consistent with a typical AV nodal reentrant tachycardia (AVNRT). Radiofrequency ablation of the slow pathway during the tachycardia immediately produced 2 : 1 AV conduction. After slow AV nodal pathway ablation an atrial tachycardia (AT) remained inducible with the earliest atrial activation around the HB region. Radiofrequency ablation at the site of earliest atrial activation interrupted the AT without AV block. AT originating from the HB region with slow pathway conduction may mimic typical AVNRT.

A Novel Pacing Maneuver to Localize Focal Atrial Tachycardia

BACKGROUND

Although focal atrial tachycardias cannot be entrained, we hypothesized that atrial overdrive pacing (AOP) can be an effective adjunct to localize the focus of these tachycardias at the site where the post-pacing interval (PPI) is closest to the tachycardia cycle length (TCL).

METHODS

Overdrive pacing was performed in nine patients during atrial tachycardia, and in a comparison group of 15 patients during sinus rhythm. Pacing at a rate slightly faster than atrial tachycardia in group 1 and sinus rhythm in group 2 was performed from five standardized sites in the right atrium and coronary sinus. The difference between the PPI and tachycardia or sinus cycle length (SCL) was recorded at each site. The tachycardia focus was then located and ablated in group 1, and the atrial site with earliest activation was mapped in group 2.

RESULTS

In both groups the PPI-TCL at the five pacing sites reflected the distance from the AT focus or sinus node. In group 1, PPI-TCL at the successful ablation site was 11 +/- 8 msec. In group 2, PPI-SCL at the site of earliest atrial activation was 131 +/- 37 msec (P < 0.001 for comparison). In groups 1 and 2, calculated values at the five pacing sites were proportional to the distance from the AT focus or sinus node, respectively.

CONCLUSIONS

The PPI-TCL after-AOP of focal atrial tachycardia has a direct relationship to proximity of the pacing site to the focus, and may be clinically useful in finding a successful ablation site.

Atrial Unipolar Potential in Radiofrequency Catheter Ablation of Atrial Tachycardia

We conducted this study to verify the efficacy of atrial unipolar potentialfor for ablation of atrial tachycardia. The morphology of atrial unipolar potential at the successful and the best unsuccessful ablation sites was analyzed in 35 patients with atrial tachycardia (sino-atrial reentrant tachycardia (SART) 15, adenosine-sensitive atrial reentrant tachycardia near the His bundle (HAT) 10, and non-reentrant ectopic atrial tachycardia (EAT) 10). The usefulness of atrial unipolar potential was compared with the Ao-Po interval. The incidences of QS pattern at the successful and the best unsuccessful sites were (successful versus unsuccessful; P, respectively) 93 versus 55%; P = 0.20 in SART, 90 versus 0%; P = 0.0001 in HAT, and 90 versus 10%; P = 0.001 in EAT. The mean Ao-Po intervals at the successful and the best unsuccessful sites were 35 versus 30 ms; NS in SART, 48 versus 45 ms; NS in HAT, and 58 versus 50 ms; NS in EAT. A significantly higher incidence of transient success at QS pattern sites was observed in SART than in HAT or EAT (n = 2 +/- 0.8 versus 0.2 +/- 0.1 and 0.1 +/- 0.1, P = 0.0005), and each transient site and final success site in SART was distributed linearly. The sensitivity and specificity of QS patterns with regard to the determination of appropriate target sites were 0.91 and 0.45 in SART, 0.9 and 1.0 in HAT, and 0.88 and 0.88 in EAT, respectively. In ablation of HAT and EAT, the QS pattern is very useful and should be given high priority when determining the optimum target site. In SART, the ablation success was often achieved by multiple, linear RF delivery near perinodal tissue, and the QS pattern could be a candidate for the optimum target site.

Focal Atrial Tachycardia II: Management

Over the last decade there have been significant changes in the treatment of focal atrial tachycardia (AT). This review concentrates on the different approaches to the treatment of focal AT. Initial therapies included antiarrhythmic medications and surgery. However, with the advent of radiofrequency ablation, and the poor efficacy of pharmacological therapy, there has been a shift toward a primary ablative approach. Several different mapping techniques have been proposed. The different techniques, including P-wave morphology and advanced three-dimensional mapping, are discussed in this review.

Focal Atrial Fibrillation Associated with Multiple Breakout Sites at the Crista Terminalis

A 34-year-old man with permanent atrial fibrillation (AF) underwent electrophysiologic testing. Spontaneous AF was observed even after successful pulmonary vein (PV) isolation of all four PVs. Intracardiac electrograms recorded from a basket catheter deployed around the crista terminalis during triggered atrial premature beats exhibited low-amplitude potentials which were suggested to reflect focal ectopic activity, preceding high-frequency atrial potentials. The firing from those focal activity sites induced a shift in the breakout sites and conduction block to the right atrium, which suggested the participation of preferential conduction. Radiofrequency catheter ablation targeting the focal origin and preferential conduction sites eliminated the AF.

Deciphering the sinus tachycardias

Sinus tachycardia is the most common rhythm disturbance encountered in clinical practice. Primary sinus tachycardia without an underlying secondary cause, despite often being associated with troublesome symptoms, is often neglected leading to multiple consultations and frustration on part of both the practitioner and the patient. The fact that primary sinus tachycardias are a heterogeneous group of disorders is seldom appreciated; hence, a firm diagnosis is rarely reached and management is haphazard. Furthermore, there may be prognostic implications for prolonged or recurrent sinus tachycardia, making it imperative that this group of arrhythmias receive adequate and appropriate attention. Normal sinus tachycardia (i.e., secondary), inappropriate sinus tachycardia, postural orthostatic tachycardia syndrome (POTS) and sinus node reentry tachycardia make up this group of arrhythmias. Their definitions, clinical features, diagnostic criteria, pathophysiologic mechanisms, and optimum management are discussed in this review.

Altered right atrial excitation and propagation in connexin40 knockout mice

BACKGROUND

Intercellular coupling via connexin40 (Cx40) gap junction channels is an important determinant of impulse propagation in the atria.

METHODS AND RESULTS

We studied the role of Cx40 in intra-atrial excitation and propagation in wild-type (Cx40(+/+)) and knockout (Cx40(-/-)) mice using high-resolution, dual-wavelength optical mapping. On ECG, the P wave was significantly prolonged in Cx40(-/-) mice (13.4+/-0.5 versus 11.4+/-0.3 ms in Cx40(+/+)). In Cx40(+/+) hearts, spontaneous right atrial (RA) activation showed a focal breakthrough at the junction of the right superior vena cava, sulcus terminalis, and RA free wall, corresponding to the location of the sinoatrial node. In contrast, Cx40(-/-) hearts displayed ectopic breakthrough sites at the base of the sulcus terminalis, RA free wall, and right superior vena cava. Progressive ablation of such sites in 4 Cx40(-/-) mice resulted in ectopic focus migration and cycle length prolongation. In all Cx40(-/-) hearts the focus ultimately shifted to the sinoatrial node at a very prolonged cycle length (initial ectopic cycle length, 182+/-20 ms; postablation sinus cycle length, 387+/-44 ms). In a second group of experiments, epicardial pacing at 10 Hz revealed slower conduction in the RA free wall of 5 Cx40(-/-) hearts than in 5 Cx40(+/+) hearts (0.61+/-0.07 versus 0.94+/-0.07 m/s; P<0.05). Dominant frequency analysis in Cx40(-/-) RA demonstrated significant reduction in the area of 1:1 conduction at 16 Hz (40+/-10% versus 69+/-5% in Cx40(+/+)) and 25 Hz (36+/-11% versus 65+/-9% in Cx40(+/+)).

CONCLUSIONS

This is the first demonstration of intra-atrial block, ectopic rhythms, and altered atrial propagation in the RA of Cx40(-/-) mice.

Catheter ablation of left atrial focal tachycardia guided by electroanatomic mapping and new insights into interatrial electrical conduction

BACKGROUND

Experience in catheter ablation of left atrial (LA) focal tachycardia and information about interatrial electrical connections during LA focal tachycardia are limited.

OBJECTIVES

The purpose of this study was to describe our experience in electroanatomic mapping-guided catheter ablation of LA focal tachycardia and to investigate interatrial electrical connections during LA focal tachycardias.

METHODS

Thirty-three patients undergoing catheter ablation for LA focal tachycardia guided by electroanatomic mapping were reported. Interatrial electrical connections were analyzed in LA focal tachycardias with biatrial electroanatomic maps.

RESULTS

Of the 35 LA focal tachycardias (cycle length 309 +/- 100 ms) mapped, 19 (54%) originated from the pulmonary veins (PVs), 6 (17%) from the mitral annulus, 3 (8.6%) from LA roof, 3 (8.6%) from LA posterior wall, 2 (5.7%) from LA appendage, and 2 (5.7%) from LA septum. Fourteen of the 19 PV tachycardias (74%) were located in proximity to PV ostia. In 14 (7 PV, 7 non-PV) LA focal tachycardias with biatrial electroanatomic maps, posterior right atrium breakthrough sites at the intercaval area were identified in 7 PV tachycardias and 1 non-PV tachycardia. Five of the 7 PV tachycardias used only the posterior breakthrough for interatrial propagation. Procedural success was achieved in 33 of 35 LA focal tachycardias (94%) in 31 patients. During 23 +/- 19 months of follow-up, 2 patients (6%) had recurrence of ablated tachycardia, and 3 (10%) developed new LA focal tachycardias.

CONCLUSIONS

The PVs and the mitral annulus were the main sources of LA focal tachycardias. The majority of PV tachycardias originated from PV ostia. A posterior interatrial connection appeared to play a major role in interatrial electrical propagation during PV tachycardias. Electroanatomic mapping facilitated precise localization of LA focal tachycardias and achievement of a high rate of ablation success.

Electrophysiologic characteristics of verapamil-sensitive atrial tachycardia originating from the atrioventricular annulus

We examined the electrophysiologic characteristics and mechanisms of verapamil-sensitive atrial tachycardia (AT) originating from the atrioventricular (AV) annulus in 18 patients. AT originated from the AV node vicinity (AV nodal AT, 10 patients) and the area distant from the AV node (non-AV nodal AT, 8 patients). There was no significant difference in the tachycardia cycle length between AV nodal and non-AV nodal AT. For both types of AT, tachycardia was inducible by atrial extrastimulation with an inverse relation between the coupling and the postpacing intervals. A single extrastimulus delivered from the earliest atrial activation site reset both ATs with an inverse relation between the coupling interval and return cycle. Also no significant difference was observed in the percentage of the excitable gap to tachycardia cycle length between AV nodal and non-AV nodal AT. Concealed entrainment was observed by rapid atrial pacing delivered from the earliest atrial activation site for both ATs. These findings suggest that these ATs are due to reentry. Intravenous administration of verapamil (2.5 to 5 mg) and adenosine triphosphate (5 mg) terminated AT in all patients. AT was successfully ablated at the earliest atrial activation site in all patients. It was shown that this form of AT in which a calcium channel-dependent substrate is involved arises not only from the vicinity of the AV node but also along the AV annulus with common electrophysiologic characteristics. These suggest the presence of a distinct entity of tachycardia more appropriately classified as verapamil-sensitive AV annular AT.

Focal Atrial Tachycardia From the Ostium of the Coronary Sinus

OBJECTIVES

The goal of this study was to characterize the electrocardiographic and electrophysiologic features and frequency of focal atrial tachycardia (AT) originating from the coronary sinus ostium (CS).

BACKGROUND

The ostium of the coronary sinus has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited.

METHODS

Thirteen patients (6.7%) of 193 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), crista terminalis (20 pole), and His positions. The P waves were classified negative, positive, isoelectric, or biphasic.

RESULTS

The mean age was 41 +/- 6 years, seven female patients, with symptoms for 8 +/- 3 years. Tachycardia was induced by programmed extra-stimuli in eight patients, was spontaneous in three patients, and in response to isoproterenol in two patients. These foci had a characteristic P-wave morphology. At the CS ostium, the P-wave was deeply negative in all inferior leads, negative or isoelectric becoming positive in lead V(1), then progressively negative across the precordium. Lead aVL was positive in all patients. Earliest EAM activity occurred at the proximal CS at 20 +/- 3 ms ahead of P-wave. Mean activation time at the successful RFA site = -36 +/- 8 ms; RFA was acutely successful in 11 of 13 patients. Long-term success was achieved in 11 of 11 over a median follow-up of 25 +/- 4 months.

CONCLUSIONS

The CS ostium is an uncommon site of origin for focal AT (6.7%). It can be suspected as a potential anatomic site of AT origin from the characteristic P-wave and activation timing. Long-term success was achieved with focal ablation in the majority of patients.

Successful catheter ablation of atrial tachycardia originating near the atrioventricular node from the noncoronary sinus of Valsalva

This report describes a patient who underwent RF catheter ablation of atrial tachycardia. Two applications of RF energy near the His-bundle region transiently terminated the tachycardia. With detailed mapping at the aortic sinus of Valsalva using a retrograde transaortic approach, the earliest atrial activation was found in the noncoronary sinus of Valsalva. Complete elimination of the tachycardia was achieved with RF energy application from this site.

Multiple Distinct Right Atrial Endocardial Origins in a Patient with Atrial Tachycardia:. Mapping and Ablation Using Noncontact Mapping

Noncontact mapping identified the endocardial origins of four distinct atrial tachycardias in a young patient with drug refractory palpitations and effected successful ablation with no recurrence of symptoms in 5 months of follow-up.

Focal Atrial Tachycardia

Background— This study investigated the electrophysiologic characteristics, atrial activation pattern, and effects of radiofrequency (RF) catheter ablation guided by noncontact mapping system in patients with focal atrial tachycardia (AT).

Methods and Results— In 13 patients with 14 focal ATs, noncontact mapping system was used to map and guide ablation of AT. AT origins were in the crista terminalis (n=8), right atrial (RA) free wall (n=3), Koch triangle (n=1), anterior portion of RA–inferior vena cava junction (n=1), and superior portion of tricuspid annulus (n=1); breakout sites were in the crista terminalis (n=5), RA free wall (n=5), middle cavotricuspid isthmus (n=2), and RA–superior vena cava junction (n=2). ATs arose from the focal origins (11 ATs inside or at the border of low-voltage zone), with preferential conduction, breakout, and spread to the whole atrium. After applications of RF energy on the earliest activation site or the proximal portion of preferential conduction from AT origin, 13 ATs were eliminated without complication. During the follow-up period (8±5 months), 11 (91.7%) of the 12 patients with successful ablation were free of focal ATs.

Conclusions— Focal AT originates from a small area and spreads out to the whole atrium through a preferential conduction. Application of RF energy guided by noncontact mapping system was effective and safe in eliminating focal AT.

Sinus tachyarrhythmias and the specific bradycardic agents: a marriage made in heaven?

A relatively novel group of drugs that inhibit the funny current in the sinus node pacemaker cells, the so-called specific bradycardic agents, are likely to play a significant role in the management of a wide range of cardiovascular disorders, including the sinus tachyarrhythmias. This comprehensive review initially provides an insight into these agents, their historical background, and their mechanism of action. It then discusses the differential diagnosis of the sinus tachyarrhythmias (normal sinus tachycardia, inappropriate sinus tachycardia, postural orthostatic tachycardia syndrome, and sinus node reentry tachycardia), elaborates on their pathophysiologic basis, and provides up-to-date evidence-based information on their optimum management. The specific bradycardic agents, by the very nature of their mode of action, may prove ideal therapies for the management of the sinus tachyarrhythmias, and this is explored at every stage.

Catheter ablation of sinoatrial re-entry tachycardia in a 2 month old infant

Successful catheter ablation of sinoatrial re-entry tachycardia in an infant has not been previously reported. This procedure is described in a 2 month old boy with tachycardia induced cardiomyopathy.

Noncontact mapping of ectopic atrial tachycardias: different characteristics of isopotential maps and unipolar electrogram

The success rate for catheter ablation of ectopic atrial tachycardia (AT) has been limited by the inherent difficulty in localizing the site of origin within the complex three-dimensional structures of the atria. The objective of the study was to determine the usefulness of a noncontact mapping system for catheter ablation of AT. Radiofrequency ablation of 25 ATs was performed using a noncontact mapping system. Three different characteristics of isopotential maps and unipolar electrogram morphologies were observed: Group 1: Isopotential maps displayed a narrow, sharp ring of colors around a white, center spot. Unipolar electrograms revealed a Q-S morphology with a rapid dV/dt. Group 2: Isopotential maps displayed a broad ring of colors with little or no white spot in the center. Unipolar electrograms revealed a low amplitude, broad and smooth Q-S morphology in front of a second component with a rapid dV/dt. Group 3: Isopotential maps displayed a broad ring of colors. Unipolar electrogams revealed a low amplitude and fractionated waveform followed by endocardial breakthrough with a gradual dV/dt. Radiofrequency catheter ablation was successful in all ATs of groups 1 and 2, and failed in two of three ATs in group 3. The overall success rate was 92%. No severe complications were observed. Noncontact isopotential mapping is helpful to identify and characterize the origin of ectopic AT. Ablation success is associated with the characteristics of isopotential maps and unipolar electrogram morphologies. The overall success rate was 92%.

Sequential ablation of orthodromic atrioventricular tachycardia and ectopic atrial tachycardia with a single application of radiofrequency energy

A 62-year-old woman with Wolff-Parkinson-White syndrome had two types of tachycardia; ectopic AT and orthodromic-type AVRT. A radiofrequency application 2 cm inside the coronary sinus ostium eliminated ectopic AT and accessory pathway conduction at once.

Clinical and electrophysiologic characteristics of left septal atrial tachycardia

OBJECTIVES

It was the purpose of this study to define the electrophysiologic (EP) identity of left septal atrial tachycardia (AT).

BACKGROUND

The clinical and EP characteristics of this particular type of arrhythmia have not been fully described.

METHODS

A total of 120 patients with AT underwent invasive EP evaluation. Five patients (two men and three women; mean age 49 +/- 15 years) with left septal AT were identified. Mapping of the right and left atrium was performed using conventional electrode catheters (five patients) and a three-dimensional electroanatomic mapping system (three patients) followed by radiofrequency (RF) ablation at the earliest site of local endocardial activation.

RESULTS

Five tachycardias with a mean cycle length of 320 +/- 94 ms were mapped, and the earliest endocardial electrogram occurred 22 +/- 10 ms before the onset of the surface P-wave. Three left septal ATs were found to be originating from the left inferoposterior atrial septum and two from the left midseptum. During tachycardia, positive (three patients), biphasic negative-positive deflection (one patient), or isoelectric (one patient) P waves were recorded in lead V(1). The inferior leads demonstrated a positive or biphasic P-wave morphology in four of five patients (80%). Four patients were given both adenosine and verapamil during AT. In three of four patients, verapamil successfully terminated AT after adenosine had failed. Adenosine successfully terminated AT in one of four patients. Successful RF ablation was performed in all patients (mean 2.2 +/- 1.7 RF applications) without affecting atrioventricular conduction properties. No recurrence of AT was observed after a mean follow-up of 14 +/- 8 months.

CONCLUSION

Left septal AT ablation is safe and effective. There was no consistent P-wave morphology associated with this particular type of AT. This arrhythmia appears to be resistant to adenosine and moderately responsive to calcium antagonists.

Anatomic determinants of atrial arrhythmias: New insights from three-dimensional mapping

The recent development of new technologies for in vivo three-dimensional mapping of arrhythmias has enabled a better understanding of the richness of intracardiac anatomy and the relationship between anatomy and arrhythmogenesis. In the present manuscript we review two new technologies for in vivo mapping of atrial arrhythmias and explores the degree to which the anatomic complexity they reveal is important in determining the physiology of both focal and macroreentrant atrial tachycardias. These observations highlight the importance of including sufficient anatomic detail in modeling studies aimed at elucidating the pathophysiology of atrial arrhythmias. (c) 2002 American Institute of Physics.

Ablation of atrial tachycardia originating from the vicinity of the atrioventricular node: significance of mapping both sides of the interatrial septum

OBJECTIVES

The purpose of the study was to examine the value of right- and left-sided mapping to identify the site of tachycardia origin.

BACKGROUND

Focal atrial tachycardia may originate from the vicinity of the atrioventricular node from either side of the interatrial septum.

METHODS

In 16 patients undergoing radiofrequency catheter ablation of perinodal atrial tachycardia, activation mapping of the right and left side of the interatrial septum was performed.

RESULTS

Atrial tachycardia originated from the right side of the interatrial septum in 10 patients (group A) and from the left side in 6 patients (group B). On the right side, earliest atrial activity preceded the onset of the P-wave by 49 +/- 15 ms in group A and by 38 +/- 8 ms in group B (NS), and it preceded the signal recorded from the right atrial appendage by 59 +/- 19 ms in group A and by 60 +/- 13 ms in group B (NS). On the left side, earliest activity preceded the onset of the P-wave by 27 +/- 16 ms in group A and by 51 +/- 6 ms in group B (<0.01), and it preceded the signal obtained from the right atrial appendage by 38 +/- 19 ms in group A and by 73 +/- 9 ms in group B (<0.01). Atrial tachycardias were successfully eliminated in all patients without impairment of atrioventricular conduction. During follow-up, two patients had a recurrence of tachycardia.

CONCLUSIONS

Mapping of only the right side cannot exclude a left-sided origin. Therefore, mapping of both sides of the interatrial septum is required prior to ablation of focal atrial tachycardia originating from the vicinity of the atrioventricular node.

Outcomes after radiofrequency catheter ablation of atrial tachycardia

The purpose of this study was to evaluate the efficacy, safety, and clinical benefit of radiofrequency catheter ablation (RFCA) in a large series of patients with atrial tachycardia (AT). The determinants of success or failure of RFCA in AT remain unclear. We evaluated the results of radiofrequency ablation in 73 women and 32 men (mean age 48 +/- 19 years) with AT. Mapping techniques were based on identification of the earliest endocardial atrial electrogram recorded during AT. AT originated from the right atrium in 91 patients and from the left atrium in 14. The cardiac ventricles were dilated in 12 patients. AT ablation was successful in 80 patients (77%) regardless of the site of origin. Age, gender, rate of tachycardia, temperature achieved during application, or presence of tachycardiomyopathy were not significant determinants of acute success by univariate analysis. There was a significantly higher acute success rate of ablation in patients with paroxysmal (88%, 45 of 51) and permanent (71%, 30 of 42) forms than in patients with repetitive forms of AT (41%, 5 of 12) (p <0.005). The mean local endocardial electrogram time (relative-to-surface P-wave onset) was -47 +/- 17 ms at successful ablation sites and -29 +/- 21 ms at unsuccessful sites (p <0.03). Ablation was unsuccessful in 25 cases. Thus, RFCA of AT can be performed with a high acute success rate. Patients with repetitive forms and those with multifocal origin had a lower acute success rate. The highest incidence of recurrences was found in anterior right atrial foci.

Electroanatomical Mapping (CARTO) of ectopic atrial tachycardia: impact of bipolar and unipolar local electrogram annotation for localization the focal origin

Electroanatomical Mapping (CARTO) allows a tridimensional localization of ectopic atrial tachycardia (EAT). No standardized recommendation exists for annotation the local activation time in EAT using this new technology. In the present study bipolar local electrogram were used for CARTO guided RF ablation of EAT. In comparison the same maps were retrospectively analyzed by annotation the unipolar local electrogram.

METHODS

In 15 consecutive patients (6m, 51+/-14 y) with EAT CARTO mapping was guided by annotation the earliest onset of the bipolar local electrogram. Following successful RF ablation the obtained EAT maps were subsequently evaluated by annotation of the earliest steepest negative intrinsic deflection of the unipolar local electrogram. Both CARTO maps were compared with regard to the region of focal EAT origin.

RESULTS

RF ablation of all 15 EAT foci guided by annotation the bipolar local electrogram with CARTO was successful with a median of 3 [1-18] pulses and a median fluoroscopy time of 10 min [4-25]. All but one focus was located in the right atrium: posterior to posteroinferior region of the terminal crest in 6, septal region in 5, anterior superior region in 3 cases. One left sided EAT was located at the septum. The bipolar CARTO map demonstrated a "small territory" location of earliest activation (extension of the focus < or =0.4 cm(2)) in 14 out of 15 patients. In a single patient the bipolar map showed several sites of earliest local activation (extension >0.4 cm(2)). On the other side the retrospectively achieved unipolar maps demonstrated an extended region of earliest local activation in 6 out of 15 patients (>0.4 cm(2)).

CONCLUSIONS

CARTO maps of EAT by annotation the earliest onset of the bipolar local electrogram provide an efficacious guide for location the focal origin. Extended regions of earliest local activation in EAT might be rather determined by annotation the unipolar in comparison to the bipolar local electrogram.

Catheter ablation for cardiac arrhythmias

The safety and efficacy of catheter ablation for treatment of most types of cardiac arrhythmias are well established. These arrhythmias and arrhythmia substrates include AVNRT, accessory pathways, focal atrial tachycardia, atrial flutter, idiopathic ventricular tachycardia, and bundle-branch re-entry. Catheter ablation is considered as an alternative to pharmacologic therapy in the treatment of these cardiac arrhythmias.

Supraventricular tachycardia

Supraventricular tachycardias (SVT) comprise those tachycardias that originate above the bifurcation of the bundle of His. They can be classified broadly as AV node dependent and AV node independent. The mechanism and clinical manifestation of SVTs, which is essential to their correct diagnosis, is reviewed. The therapeutic management of SVTs, including acute and chronic drug therapy and catheter ablation, is discussed also.

[Long-term efficacy of radiofrequency catheter ablation in atrial tachycardia]

INTRODUCTION AND OBJECTIVES

Radiofrequency ablation has shown to be an effective treatment for supraventricular tachycardias including flutter and atrial tachycardia, however the clinical information available on atrial tachycardia is limited. The aim of this study was to evaluate the immediate and long term effectiveness of radiofrequency ablation in patients with atrial tachycardia and to establish predictors of effectiveness and arrhythmia recurrence.

METHODS

We analyzed a series of 126 procedures of atrial tachycardia ablation in 117 patients (69% women) with a mean age of 50 +/- 19 years.

RESULTS

Ninety-one percent of the foci were located in the right atrium. A mean of 6 applications were necessary to achieve an efficacy of 74% during the first procedure with a total of 80%. The only predictor of ablation success was the number of foci being smaller in multifocal compared to unifocal (p < 0.01) whereas for recurrences a less premature electrogram at the application point (p = 0.02) was predictive of ablation success. Over a follow-up of 34 +/- 19 months 7.4% of patients had recurrent atrial tachycardia. The probability of recurrence at one year calculated by the Kaplan-Meier method was 12%. Seventy-one percent of the recurrences occurred during the first 3 months after ablation.

CONCLUSIONS

Ablation is an effective, safe procedure for short and long term treatment of patients with atrial tachycardia. Effectiveness depends on the number of foci while the recurrence rate is related to the prematurity of atrial electrogram at the application point.

The ligament of Marshall: a structural analysis in human hearts with implications for atrial arrhythmias

OBJECTIVES

We sought to study the anatomy of human ligament of Marshall (LOM).

BACKGROUND

Although the LOM has been implicated in the genesis of focal atrial tachyarrhythmias, its gross anatomic and microscopic features in humans hearts have not been completely defined.

METHODS

We studied seven postmortem human hearts from five men and two women with a mean age of 52 +/- 26 years. Four did not have any heart disease. One woman had dilated cardiomyopathy, and two men had chronic atrial fibrillation. A block of tissue encompassing the LOM from the coronary sinus (CS) cephalad, between the atrial appendage and left pulmonary veins, was dissected. Serial sections from this tissue were then stained with hematoxylin and eosin, trichrome, and/or tyrosine hydroxylase.

RESULTS

The LOM consists of multiple sympathetic nerve fibers, ganglia, blood vessels and multiple myocardial tracts (Marshall Bundles) insulated by fibrofatty tissue. One or more myocardial tracts was inserted directly into the left atrial free wall and CS. The distance between insertion sites was 7.8 +/- 2.5 mm. Nerve fibers, some tyrosine hydroxylase positive, were present within the fibrofatty matrix and within the myocardial tracts.

CONCLUSIONS

Human LOM 1) is innervated by sympathetic nerve fibers; 2) is more complex than the LOM in canine hearts; and 3) has multiple myocardial tract insertions into the left atrial free wall and CS, forming a substrate of reentry. Radiofrequency catheter ablation from the CS may fail to reach the free wall insertion.

Electrophysiologic findings of a patient with inappropriate sinus tachycardia cured by selective radiofrequency catheter ablation

Radiofrequency catheter ablation (RFCA) for inappropriate sinus tachycardia (IST) is associated with a high recurrence rate and sometimes requires pacemaker implantation, especially after extensive ablation. We report a patient with drug-refractory IST who was successfully treated by selective RFCA to the 2 earliest activation sites. During tachycardia, the earliest atrial activation preceded the surface P wave by 50 ms or more, whereas it was only 27 ms for the rest of the right atrium after ablation. Our patient had the longest activation period during tachycardia among the reported patients. In IST patients, a longer activation time at the site of the earliest atrial activation may imply that the abnormality is confined to a small area within the sinus node and may predict the efficacy of selective RFCA.

Temperature-sensitive focal atrial tachycardia in the left atrium

Temperature sensitivity has not been reported in focal atrial tachycardia. We describe a patient with a left atrial tachycardia whose tachycardia rate was affected by hot and cold drinks. The effects were still evident after autonomic blockade. The arrhythmia focus was located at the entrance of the left upper pulmonary vein. Radiofrequency ablation was carried out, which proved to be difficult, but it was successful after several applications of energy, suggesting an epicardial location of the arrhythmia focus. Sensitivity of atrial tachycardia rate to the temperature of food or drink ingested suggests a left atrial focus with a posterior and possibly epicardial location.

Catheter ablation in the year 2000

After its introduction in 1987, radiofrequency catheter ablation became established as a safe and effective therapy for the cure of many cardiac arrhythmias in people. The possibility of assessing the relationship between the anatomical target and the electrophysiologic changes produced by radiofrequency pulse delivery has also provided significant improvement in the physician's knowledge of the pathophysiology of the underlying rhythm disturbance. Nowadays, using this therapy, success rates well above 90% with recurrence rates lower than 5% are expected after treatment of most regular supraventricular arrhythmias. As catheter ablation techniques develop, success rates in the range of those obtained for regular supraventricular arrhythmias are expected in the future in the treatment of regular ventricular and irregular supraventricular arrhythmias.