Ripple mapping-guided atrial tachycardia ablation following open-heart surgery.

Ripple mapping can make the visualization of activation conduction on a 3-dimensional voltage map and is useful tool for scar-related organized atrial tachycardia (AT). This study sought to assess the efficacy of ripple mapping for interpreting reentrant circuits and critical isthmus in postoperative ATs. 34 consecutive patients with a history of mitral valve surgery (mean age, 54.5 ± 12.4 years) underwent high density (HD) RM during ATs with CARTO3v4 CONFIDENSE system. The voltage activation threshold was determined by RM over a bipolar voltage map. The identification of underlying mechanisms and ablation setting was based on RM without reviewing activation mapping. A total of 41 ATs (35 spontaneous, 6 induced) were characterized. 39 reentry circuits were successfully mapped (cycle length, 256 ± 43 ms). Of the 41 ATs, 28 were confirmed by ripple mapping alone (68%), and 12 (29%) by ripple mapping and entrainment mapping. Of 12 ATs in the left atrium, 9 (75%) needed entrainment to confirm, compared with 5 (17.8%) in the right atrium. Primary endpoint after initial ablation set was achieved in 32 of the 34 patients (94.1%). Freedom from atrial arrhythmias was 79.4% after the follow-up of 12 ± 5 months. Of the seven patients with recurrence, three underwent the repeated catheter ablation. Ripple mapping precisely delineated reentrant circuits in post-cardiac surgery AT resulting in a high success rate of ablation. Entrainment maneuvers remain useful for elucidation of complex AT circuits.

Successful Ablation of Atrial Tachycardia Originating from Inside the Single Atrium and Conduit After a Fontan Operation.

An 18-year-old male who had a past medical history of an intracardiac total cavopulmonary connection (TCPC) operation was referred to our hospital for radiofrequency catheter ablation (RFCA) of supraventricular tachycardia (SVT). Two types of SVTs were induced, and 3-dimensional (3D) maps were created using an ultra-high-density 3-dimensional mapping system (Rhythmia). The earliest atrial activation site (EAAS) of SVT1 was at the superior part of the conduit, and the EAAS of SVT2 was at the inferior part of the single atrium (SA). The SVTs were terminated by energy deliveries to the EAAS from the conduit in SVT1 and from inside the single atrium in SVT2. Detailed maps of the SVTs were important to understand the mechanisms of the SVTs. The Rhythmia system was useful for the detailed mapping of complex arrhythmias. The use of Rhythmia in patients after a TCPC is difficult, because puncturing the TCPC conduit and proceeding and manipulating the Orion catheter via a narrow puncture hole are difficult. We were the first to succeed in ablating two atrial tachycardias (ATs) originating from the inside and outside of the conduit after a TCPC operation by using an ultra-high-density 3-dimensional mapping system.

Catheter Ablation of Focal Atrial Tachycardia Using Remote Magnetic Navigation.

OBJECTIVES: The outcomes of catheter ablation in focal atrial tachycardia (AT) using remote magnetic navigation (RMN) are still controversial. The objectives of this study were to assess the acute and long-term outcomes of catheter ablation in focal AT using RMN. BACKGROUND: A total of 53 patients with focal AT who underwent catheter ablation using RMN were included. Thirty-six patients had structural heart disease, including previous atrial fibrillation ablation and heart surgery (abnormal group), and the remaining 17 patients had no structural heart disease (normal group). METHODS: In 53 patients, a total of 56 atrial foci were found. Acute success of the primary ablation was obtained in 52 patients (98%). Mean procedure duration was 109 ± 35 min, ablation duration was 401 sec (interquartile range [IQR], 332 sec), and fluoroscopy time was 5.0 min (IQR, 3.0 min). After a mean follow-up of 31 ± 18 months, 47 patients (89%) were free from focal AT. No major complications were observed. In the abnormal group, age and target atrium volume were higher and the left ventricular ejection fraction was lower when compared to the normal group. However, there were no significant differences in procedure duration (normal group 106 ± 31 min vs abnormal group 111 ± 37 min); ablation duration (normal group 457 sec [IQR, 412 sec] vs abnormal group 378 sec [IQR, 217 sec]); fluoroscopy time (normal group 4.2 min [IQR, 3.0 min] vs abnormal group 5.4 min [IQR, 3.3 min]); acute success rate (normal group 100% vs abnormal group 97%); and long-term success rate (normal group 88% vs abnormal group 89%) between the two groups (P>.05). CONCLUSION: Our study has demonstrated that catheter ablation of focal AT using RMN is safe and effective, with low fluoroscopy exposure.

Electrocardiographic spatial loops indicate organization of atrial fibrillation minutes before ablation-related transitions to atrial tachycardia.

BACKGROUND: During ablation for atrial fibrillation (AF), it is challenging to anticipate transitions to organized tachycardia (AT). Defining indices of this transition may help to understand fibrillatory conduction and help track therapy. OBJECTIVE: To determine the timescale over which atrial fibrillation (AF) organizes en route to atrial tachycardia (AT) using the ECG referenced to intracardiac electrograms. METHODS: In 17 AF patients at ablation (58.7±9.6years; 53% persistent AF) we analyzed spatial loops of atrial activity on the ECG and intracardiac electrograms over successive timepoints. Loops were tracked at precisely 15, 10, 5, 3 and 1min prior to defined transitions of AF to AT. RESULTS: Organizational indices reliably quantified changes from AF to AT. Spatiotemporal AF organization on the ECG was identifiable at least 15min before AT was established (p=0.02). CONCLUSIONS: AF shows anticipatory global organization on the ECG minutes before AT is clinically evident. These results offer a foundation to establish when AF therapy is on an effective path, and for a quantitative classification separating AT from AF.

A Prospective Study of Ripple Mapping in Atrial Tachycardias: A Novel Approach to Interpreting Activation in Low-Voltage Areas.

BACKGROUND: Post ablation atrial tachycardias are characterized by low-voltage signals that challenge current mapping methods. Ripple mapping (RM) displays every electrogram deflection as a bar moving from the cardiac surface, resulting in the impression of propagating wavefronts when a series of bars move consecutively. RM displays fractionated signals in their entirety thereby helping to identify propagating activation in low-voltage areas from nonconducting tissue. We prospectively used RM to study tachycardia activation in the previously ablated left atrium. METHODS AND RESULTS: Patients referred for atrial tachycardia ablation underwent dense electroanatomic point collection using CARTO3v4. RM was played over a bipolar voltage map and used to determine the voltage "activation threshold" that differentiated functional low voltage from nonconducting areas for each map. Ablation was guided by RM, but operators could perform entrainment or review the isochronal activation map for diagnostic uncertainty. Twenty patients were studied. Median RM determined activation threshold was 0.3 mV (0.19-0.33), with nonconducting tissue covering 33±9% of the mapped surface. All tachycardias crossed an isthmus (median, 0.52 mV, 13 mm) bordered by nonconducting tissue (70%) or had a breakout source (median, 0.35 mV) moving away from nonconducting tissue (30%). In reentrant circuits (14/20) the path length was measured (87-202 mm), with 9 of 14 also supporting a bystander circuit (path lengths, 147-234 mm). In breakout tachycardias, splitting of wavefronts resulted in 2 to 4 incomplete circuits. RM-guided ablation interrupted the tachycardia in 19 of 20 cases with the first ablation set. CONCLUSIONS: RM helps to define activation through low-voltage regions and aids ablation of atrial tachycardias.

Transbaffle catheter ablation of atrial re-entrant tachycardia within the pulmonary venous atrium in adult patients with congenital heart disease.

AIMS: Catheter ablation of atrial re-entrant tachycardia in patients after atrial switch procedure for transposition of the great arteries or with a Fontan circulation is technically challenging if the critical part of the re-entry circuit is located within the pulmonary venous atrium (PVA). We report our experience in transbaffle access (TBA) to the PVA for ablation of atrial re-entrant tachycardia focusing on technical details. METHODS AND RESULTS: In eight patients, six after Mustard procedure and two with a Fontan circulation, endocardial mapping of atrial re-entrant tachycardia revealed the critical part of the re-entry circuit within the PVA. A total of 10 ablation procedures were performed. Detailed angiographic assessment of the anatomy of the systemic and pulmonary venous atria was performed prior to baffle puncture. Transbaffle access was successfully established with a standard transseptal needle in 9 of 10 procedures. No major complications occurred. At the end of the procedure and the removal of the transseptal sheath, there was no residual shunt in any patient. CONCLUSION: Transbaffle access to the PVA for ablation of atrial re-entrant tachycardia is feasible, less invasive than alternative approaches and can be safely applied in patients after Mustard procedure or with a Fontan circulation. However, the rigidity of prosthetic material may preclude baffle puncture at least in a subset of those patients.

Radiofrequency ablation of focal atrial tachycardia: Benefit of electroanatomical mapping over conventional mapping.

BACKGROUND: Catheter ablation is a proven therapy of focal atrial tachycardia. However limited information is available about the additional value of electroanatomical over conventional mapping methods for this specific arrhythmia. METHODS: Consecutive catheter ablation procedures of FAT were analyzed in two cardiology centres. Only conventional mapping was used in 30 of the 60 procedures whereas additionally CARTO mapping was performed in another 30 procedures. Acute, six-month success rate, and procedural data were analyzed. RESULTS: Localization of ectopic foci is congruent with previously published data. There was no statistically significant difference between procedure time and fluoroscopy time using additionally CARTO mapping, compared to conventional mapping only. Acute success rate was higher in procedures guided by CARTO mapping than in procedures based on conventional mapping (27/30 vs. 18/30, p = 0.0081). During the 6-month follow-up period there was a better outcome (p = 0.045) in case of CARTO guided procedures (success: 11 cases, partial success: 12 cases, failure: 4 cases) compared to conventional mapping (success: 4 cases, partial success: 18 cases, failure: 7 cases). CONCLUSIONS: Catheter ablation of focal atrial tachycardias using the CARTO electroanatomical mapping system seems to provide higher acute and 6-month success rate compared to ablation using conventional mapping methods only.

A case of atrial tachycardia treated with ivabradine as bridge to ablation.

Ivabradine is indicated in cardiac failure and ischemia to reduce sinus rate by inhibition of the pacemaker I(f) current in sinoatrial node. We report a case of an 18-year-old woman with left atrial tachyarrhythmia resistant to several antiarrhythmic drugs and to electric cardioversion who responded only to ivabradine, which significantly reduced heart rate without abolishing the arrhythmia itself. An ectopic focus in the ostium of left pulmonary veins was found and the patient was successfully ablated. We suggest that ivabradine might be therefore useful in the treatment of supraventricular tachyarrhythmias due to an enhanced automaticity.

Overdrive pacing from downstream sites on multielectrode catheters to rapidly detect fusion and to diagnose macroreentrant atrial arrhythmias.

BACKGROUND: Entrainment criteria for macroreentrant arrhythmias are based on detecting fusion between tachycardia and paced wavefronts, but this is often difficult for atrial tachycardias (AT) after ablation of atrial fibrillation. METHODS AND RESULTS: With the use of a multipolar catheter, pacing was performed from electrodes within the coronary sinus showing activation later than adjacent electrodes (downstream overdrive pacing) during 66 ATs in 62 patients: 20 cavotricuspid isthmus-dependent ATs, 20 perimitral ATs, 13 focal ATs with sequential coronary sinus activation, and 13 other macroreentrant left atrial ATs. The paced cycle length was 10 to 30 milliseconds below the tachycardia cycle length (TCL), and activation at the neighboring upstream electrodes was assessed. Downstream overdrive pacing at 48 sites close to a macroreentrant circuit (PPI-TCL <40 milliseconds, where PPI is postpacing interval) produced constant fusion demonstrated by a long stimulus to upstream atrial electrogram interval (S-Au) >75% TCL and was consistent with orthodromic activation of the upstream site despite its close proximity to the pacing site. In contrast, downstream overdrive pacing at 18 sites during focal AT or remote from the macroreentrant AT circuit (PPI-TCL >40 milliseconds) always demonstrated a comparatively short S-Au <25% of TCL (12±4% versus 89±4% of TCL; P<0.001), consistent with direct activation. CONCLUSIONS: Selection of a downstream activation site for overdrive pacing can facilitate rapid recognition of macroreentry and proximity to the reentry circuit using a single multielectrode catheter by recognizing a PPI-TCL <40 milliseconds and S-Au >75% of TCL. Recognition of intracardiac constant fusion with this method is a novel criterion for transient entrainment.

Pulmonary artery mapping for differential diagnosis of left-sided atrial tachycardia.

BACKGROUND: Distinguishing left-and right-sided atrial tachycardia (AT) is often challenging. The coronary sinus (CS) provides information only concerning the anterior left atrium (LA). Potentials recorded in the pulmonary artery (PA) have been substituted for those of the upper posterior LA because of their anatomical relationship. METHODS AND RESULTS: Three patterns were designed, using potentials in the PA, right atrium (RA) and CS, to predict the side of AT. Two patterns were for left-sided AT and 1 pattern was for right-sided AT. Ten left-sided and 11 right-sided ATs were investigated regardless of mechanism. Electrode catheters were inserted in the RA, His bundle region, and CS, and an ablation catheter was inserted into the left and/or right PA. The sequences from these catheters were analyzed before detailed electroanatomical mapping. Patterns were obtained for 20 of 21 ATs. The mechanism was focal in 16 ATs and macroreentry in 5. The method predicted left-sided AT with a sensitivity of 78%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 84%, and an accuracy of 90%. CONCLUSIONS: The use of potentials in PA combined with conventional RA and CS electrograms is useful for distinguishing left-sided AT from right-sided AT, regardless of mechanism.

Frequency spectra analysis suggests outcomes in patients with paroxysmal atrial fibrillation.

BACKGROUND AND AIM: The purpose of this study was to determine the role of dominant frequency (DF) and organised index (OI) in outcomes of pulmonary vein (PV) isolation for paroxysmal atrial fibrillation (AF). METHODS: OI and DF of electrograms in coronary vein (CS) during AF were obtained by frequency spectra analysis in 60 patients with paroxysmal AF who underwent PV isolation. Based on the results of 12 months follow up, 14 patients with recurrent AF were included in group 1 and 46 patients with sinus rhythm were included in group 2. RESULTS: In group 1, no spectral component was reduced by PV isolation. Spectral components were reduced by PV isolation in 23 patients in group 2. The changes of DF after PV isolation was significantly different between groups 1 and 2 (1.2 ± 1.2 vs. 2.4 ± 1.3, p = 0.01); the increment of OI after PV isolation in group 1 was significantly lower than in group 2 (9 ± 13% vs. 22 ± 17%, p = 0.02. CONCLUSIONS: A decrease in DF and an increase in OI after PV isolation may suggest a better clinical outcome.

Catheter ablation of focal atrial tachycardia originating from a donor heart after bicaval orthotopic heart transplantation guided by a noncontact mapping system.

A 19-year-old man who underwent bicaval orthotopic heart transplantation for idiopathic dilated cardiomyopathy complained of palpitations 2 weeks after the heart transplantation. An ECG revealed paroxysmal atrial tachycardia (AT) with a cycle length of 260 ms and the P wave morphology of the AT was similar to that during sinus rhythm. Echocardiography showed normal contraction. No rejection, vasculopathy, or infection was observed. An electrophysiologic study and catheter ablation guided by a noncontact mapping system were performed due to drug refractory AT. The AT was induced spontaneously by isoproterenol infusion. The activation sequence of the AT exhibited a focal pattern, and the breakout site of the AT into the donor right atrium was just 12 mm below the breakout site of the donor sinoatrial node. Radiofrequency catheter ablation eliminated this AT and resulted in an improvement in the symptoms.

Focal atrial tachycardia arising from the cavotricuspid isthmus with saw-tooth morphology on the surface ECG: electrocardiographic and electrophysiologic characteristics.

BACKGROUND: Limited information is available about focal atrial tachycardia (AT) arising from cavotricuspid isthmus (CTI). OBJECTIVE: The purpose of this study is to evaluate the electrocardiographic and electrophysiologic characteristics of a focal AT arising from the CTI. METHODS: From a consecutive series of 92 patients undergoing radiofrequency catheter ablation (RFCA) for focal AT, three (4.4%) patients (three men) with a focal AT arising from the CTI were studied. RESULTS: The median age was 71 years (range, 50 to 81 years). None of the patients had a history of CTI-dependent atrial flutter. The electrocardiogram (ECG) of a focal AT showed a significant negative F-wave in the inferior leads. Focal AT could be reproducibly initiated and terminated with programmed stimulation. The focus of the tachycardia was localized to the central isthmus in two and the paraseptal isthmus in one patient. The median tachycardia cycle length was 275 ms (range, 260 to 310 ms). In two patients, the focal AT was adenosine insensitive. In all of the patients, tachycardia was entrained from multiple right atrial sites, including the earliest activation site. RFCA was acutely successful in all patients. Long-term success was achieved in all patients over the median follow-up of 18 months (range, 6 to 33 months). CONCLUSIONS: Cavotricuspid isthmus is an uncommon site of origin for focal AT. This focal AT has unique electrocardiographic characteristics such as saw-tooth morphology on ECG and is suggested to be caused by a focal reentrant circuit located at the CTI. Long-term success is achieved with focal ablation.

Inducible atrial tachycardias with multiple circuits in a stepwise approach are associated with increased episodes of atrial tachycardias after catheter ablation.

BACKGROUND: Atrial tachycardia (AT) is commonly observed during catheter ablation (CA) in patients with atrial fibrillation (AF) undergoing a stepwise extensive CA. In this study, we examined the hypothesis that the presence of multiple inducible ATs (multiple-ATs), which allow for latent multiple reentrant circuits, might increase the potential for following AT episodes after CA. METHODS AND RESULTS: The study population consisted of 347 consecutive AF patients undergoing CA with a stepwise approach. A total of 366 ATs (tricuspid isthmus dependent, 101; mitral annulus, 62; septal, 26; roof dependent, 22; left atrial anterior wall, 13; upper loop, 8; surrounding the left pulmonary veins, 6; surrounding the right pulmonary veins, 6; left atrial appendage, 4; and Cs ostium, 3) occurring during the CA were found in 216 (62.2%) of 347 patients. Multiple-ATs (≥2) during the CA were observed in 93 (26.8%) of 347 patients. The incidence of AT episodes significantly increased as the number of inducible ATs increased (no AT, 7.8%; single AT, 13.7%; and multiple-ATs, 24.2%; P < .001), and multiple-ATs were an independent risk factor for AT episodes (3.07 [1.39-6.78]; P = .005). The impact of the multiple-ATs on the AT episodes was pronounced especially in the patients with coinducible residual AF (with coresidual AF vs without coresidual AF, 8.1% vs 47.7%; P < .001). CONCLUSIONS: The presence of an atrial substrate allowing for multiple-ATs was associated with increased AT episodes during follow-up.

Respiratory cycle-dependent atrial tachycardia: prevalence, electrocardiographic and electrophysiologic characteristics, and outcome after catheter ablation.

BACKGROUND: Little is known about the tachyarrhythmias relating to respiration. Case reports presented patients with respiratory cycle-dependent atrial tachycardias (RCATs), which cyclically emerge after starting inspiration and cease during expiration. OBJECTIVE: The aim of the present study was to elucidate the prevalence, characteristics, and long-term outcome after radiofrequency catheter ablation (RFCA) of RCATs. METHODS: The electrocardiographic and electrophysiologic properties and results of RFCA were analyzed in 60 patients with a total of 71 focal atrial tachycardias (ATs). RESULTS: Nine RCATs (13%) were observed in 7 patients (12%). RCATs were irregular, with a mean cycle length ranging from 220 to 650 ms, and developed incessantly accounting for 32% ± 14% of the 24-hour heartbeats. The P-wave morphology was positive or biphasic (positive to negative) in V1, and positive in I and II. The electroanatomical mapping demonstrated a centrifugal activation pattern, with the earliest site located at the antrum of the right superior pulmonary vein (RSPV), inside the RSPV, and inside the superior vena cava (SVC) in 4, 2, and 3 RCATs, respectively. Radiofrequency energy delivery at the earliest site or the electrical isolation of the RSPV and SVC suppressed all RCATs. During a follow-up of 25 ± 15 months, 1 RCAT recurred and was eliminated in a second procedure. CONCLUSION: RCATs were observed in 13% of the focal ATs. As presumed from the P-wave morphologies, their foci converged around the RSPV or inside the SVC. RFCA was effective to eliminate RCATs.

An unusual atrial tachycardia in a patient with Friedreich ataxia.

We present the unusual association of an atrial tachycardia with Friedreich ataxia. The arrhythmia was initially suspected to be focal in origin; however, use of a three-dimensional mapping system demonstrated that the tachycardia was macro-reentrant. This was subsequently treated successfully by linear ablation.

Electrogram analysis at the His bundle region and the proximal coronary sinus as a tool to predict left atrial origin of focal atrial tachycardias.

AIMS: Early activation at the His bundle (HB) region or proximal coronary sinus (CS) during focal atrial tachycardias (FATs) often necessitates biatrial mapping. Analysis of CS electrograms (EGMs) consisting of a near-field (N) component from CS musculature and a far-field (F) component from left atrial (LA) myocardium can uncover LA activation preceding right atrial (RA) activation. A similar pattern might be observed at the HB. METHODS AND RESULTS: Eight patients underwent RA and LA pacing testing the hypothesis that N and F components originating from the RA and LA septum are present in the HB atrial EGM (Pacing group). In this group N preceded F (N-F sequence) in all, while F preceded N (F-N sequence) in seven of eight patients during RA and LA pacing, respectively. Twenty-seven patients with FAT demonstrating earliest activation at the HB or proximal CS during limited RA mapping were also studied (FAT group). Two observers analysed the EGMs at the earliest site during FAT. They found an N-F sequence in 17 (94%) and 16 (89%) of 18 RA FAT and an F-N sequence in seven (78%) and eight (89%) of nine LA FAT, respectively. The F-N sequence predicted the need for LA access with a sensitivity of 78 and 89% and a specificity of 94 and 89%. CONCLUSION: Near-field and F components from RA and LA activation can be identified in the HB atrial EGM. Earliest atrial EGM analysis at the HB or CS can predict the need for LA access during FAT ablation.

Atrial tachycardias in patients with congenital heart disease: a minimally invasive simplified approach in the use of three-dimensional electroanatomic mapping.

AIMS: Atrial tachycardia (AT) is a common complication after repair of congenital heart disease (CHD). This two-centre prospective study evaluated the ability of three-dimensional electroanatomic mapping (EAM) to guide ablation of ATs in this particular population with a minimally invasive simplified approach. METHODS AND RESULTS: Thirty-one consecutive patients (mean age 26 ± 17 years) with AT after repair of CHD were treated with a very limited number of intracavitary catheters and a specific setting of the Window of Interest (WoI) for the ablation of post-surgical ATs. A single-intracavitary catheter approach was performed in 22 patients, whereas an overall use of two intracavitary catheters in the other nine patients. Thirty-one patients exhibited 41 ATs. Seventy-six per cent of these were macro-reentrant ATs (MRATs), and 24% were focal ATs (FAT). The mid-diastolic isthmus (MDI) was located in the right atrial free wall (RAFW) in 82.8% of MRATs. Also in FATs, the RAFW was the most common site (77.8%) of the ectopic focus. Fifty-eight per cent of MRATs showed a double-loop reentry, with both loops sharing the same MDI in all cases. In 87% of cases, the abolition of the MRAT was obtained by applying radiofrequency energy to the MDI. Ninety per cent of FATs were successfully ablated. Mean conduction velocity and voltage amplitude had significantly lower values in successfully treated than in unsuccessfully treated MRATs. CONCLUSION: Three-dimensional EAM, performed with a minimally invasive simplified approach and by using a specific parameter setting of the WoI, showed to be very effective to guide ablation of ATs in CHD patients.