Electrical Isolation of Both Left Pulmonary Veins by a Single Left Atrial Endocardial Radiofrequency Energy Application: Ablation of Marshall Bundle Bypass

The muscular sleeve contained within the ligament of Marshall (Marshall Bundle, MB) has been implicated in triggering and/or maintaining atrial fibrillation. Its connections may form a conduit between the left atrium (LA) and the left pulmonary veins (PVs) and challenge PV isolation attempts. In this case, radiofrequency (RF) ablation at antra of both left PVs failed to affect venous electrical activity. However, isolation of both PVs occurred simultaneously with a single, short (14 seconds) RF energy application at the mitral isthmus. This was delivered at a site recording a complex continuous electrogram (duration 100 ms), interpreted as the site of a single connection between LA and MB. (PACE 2012; 35:e325–e329)     

Left‐Sided Atrial Flutter Originating in the Coronary Sinus after Radiofrequency Ablation of Atrial Fibrillation

We describe a case of atypical atrial flutter presenting 1 year after radiofrequency ablation for atrial fibrillation (AF). Electrophysiologic study showed a reentry circuit involving the inferolateral aspect of the mitral annulus and the coronary sinus (CS); however, a mitral isthmus line did not terminate the arrhythmia. Participation of the proximal CS musculature in the circuit suggested a possible target for ablation. Radiofrequency energy applications from within the CS terminated the tachycardia. Mapping and ablation within the CS should be considered in patients with post‐AF ablation arrhythmias, particularly when the mitral annulus appears to be involved in the tachycardia circuit. (PACE 2010; 33:e96–e99)     

Ablation of Atrioventricular Nodal Reentrant Tachycardia in a Patient with Reversal of Slow and Fast Pathways Inputs into the Atrioventricular Node

We report a case of atrioventricular nodal reentrant tachycardia (AVNRT) coexistent with His bundle anomaly and atrial septal defects. The His‐bundle potential was recorded at the coronary sinus (CS) ostium. Fractionated atrial potentials and an A:V electrogram ratio 1:3 were recorded at the anterior septum of the tricuspid annulus approximately 2 cm from CS ostium. Radiofrequency catheter ablation at the anterior septum of the tricuspid annulus effectively eliminated AVNRT. (PACE 2012; 35:e17–e19)     

Primary Prevention of Atrial Fibrillation: Does the Atrial Lead Position Influence the Incidence of Atrial Arrhythmias in Patients with Sinus Node Dysfunction? Results from the PASTA Trial

Introduction: PASTA (pacing of the atria in sinus node disease) is a prospective and randomized trial, assessing the effect of different atrial lead positions on the atrial fibrillation (AF) incidence in patients with sinus node disease (SND). Method: The atrial lead position is randomized to: (a) free right atrial wall, (b) right atrial appendage (RAA), (c) coronary sinus ostium (CS‐Os), or (d) dual site right atrial pacing (CS‐Os + RAA). The pacemakers (Vitatron Selection 9000 or Prevent AF, Vitatron B.V., Arnhem, The Netherlands) are programmed in DDDR 70 mode and the total follow‐up duration is 24 months. To describe the atrial rhythm state, pacemaker‐derived data (arrhythmia counter) were assessed for AF episodes. AF was considered as evident, if the AF burden (time in AF related to follow‐up interval) was >1% (i.e., 15 min/d). Follow‐up data after 24 months were evaluated. Results: The analysis evaluates 142 patients (77 male, 74.5 ± 7.8 years). There was no statistical significant difference with respect to the occurrence of AF between the four groups after 24 months (A: 36%; B: 38%, C: 32%, D: 48%). The percentage of atrial/ventricular pacing was in A: 78/76%, in B: 84/81%, in C: 70/65%, and in D: 79/69%. These differences were not significant. Conclusion: The evaluation of the AF burden >1% and the total AF burden after 24 months did not show differences in the incidence of AF in patients with dual chamber pacemaker therapy for SND. We were not able to demonstrate a significant influence of right atrial lead position on the incidence of AF recurrence.     

Superior Vena Cava Stenosis after Radiofrequency Catheter Ablation for Electrical Isolation of the Superior Vena Cava

Ectopic beats originating from the superior vena cava (SVC) may initiate atrial fibrillation. This report describes a patient undergoing radiofrequency catheter ablation for electrical isolation of the SVC resulting in SVC stenosis. Noncircumferential lesion sets for SVC isolation to reduce ablation times may be preferred. (PACE 2010; e36–e38)     

Interatrial conduction correlates with optimal atrioventricular timing in cardiac resynchronization therapy devices

Background: Echocardiographic optimization of the atrioventricular delay (AV) may result in improvement in cardiac resynchronization therapy (CRT) outcome. Optimal AV has been shown to correlate with interatrial conduction time (IACT) during right atrial pacing. This study aimed to prospectively validate the correlation at different paced heart rates and examine it during sinus rhythm (Sinus). Methods: An electrophysiology catheter was placed in the coronary sinus (CS) during CRT implant (n = 33). IACT was measured during Sinus and atrial pacing at 5 beats per minute (bpm) and 20 bpm above the sinus rate as the interval from atrial sensing or pacing to the beginning of the left atrial activation in the CS electrogram. P‐wave duration (PWd) was measured from 12‐lead surface electrocardiogram, and the interval from the right atrial to intrinsic right ventricular activation (RA‐RV) was measured from device electrograms. Within 3 weeks after the implant patients underwent echocardiographic optimization of the sensed and paced AVs by the mitral inflow method. Results: Optimal sensed and paced AVs were 129 ± 19 ms and 175 ± 24 ms, respectively, and correlated with IACT during Sinus (R = 0.76, P < 0.0001) and atrial pacing (R = 0.75, P < 0.0001), respectively. They also moderately correlated with PWd (R = 0.60, P = 0.0003 during Sinus and R = 0.66, P < 0.0001 during atrial pacing) and RA‐RV interval (R = 0.47, P = 0.009 during Sinus and R = 0.66, P < 0.0001 during atrial pacing). The electrical intervals were prolonged by the increased atrial pacing rate. Conclusion: IACT is a critical determinant of the optimal AV for CRT programming. Heart rate‐dependent AV shortening may not be appropriate for CRT patients during atrial pacing. (PACE 2011; 34:443–449)     

Radiofrequency Catheter Ablation of Parasystole Originating from the Inferior Vena Cava

A 76‐year‐old man with a history of atrial septal defect repair underwent radiofrequency (RF) ablation of typical atrial flutter. During electrophysiological study, incessant sharp potentials were recorded, originating from the ostium of the inferior vena cava (IVC), and dissociated from atrial activity. During sinus rhythm, these potentials propagated to the atria and caused premature complexes when falling beyond the atrial refractory period. Electro‐anatomical mapping revealed the presence of the earliest potential in the postero‐lateral ostium of the IVC, propagating to the septal region. After RF isolation of the IVC, the patient has remained arrhythmia‐free over a 5‐year follow‐up. (PACE 2010; e62–e64)     

Mapping and Isolation of the Pulmonary Veins Using the PVAC Catheter

Objectives: We aimed to investigate the feasibility, efficacy, and safety of the pulmonary vein ablation catheter (PVAC) catheter (a novel multielectrode catheter using duty‐cycled bipolar and unipolar radiofrequency energy, Medtronic, Minneapolis, MN, USA) to completely isolate the pulmonary veins (PVs). Methods: Twenty‐seven patients (60 ± 8 years) with paroxysmal atrial fibrillation (AF) underwent PV isolation with the PVAC catheter. PVAC was used for both mapping and isolation of the PVs (PVAC‐guided ablation). After PVAC ablation, presence/absence of PV potentials (PVP) was verified using a conventional circular mapping catheter. In case of residual PVP on the circular catheter, PVAC ablation was continued. Results: After PVAC‐guided ablation 99 of 106 PVs (93%) and 21 of 27 patients (78%) were proven to be isolated. Failure to isolate was due to a mapping failure in four right‐sided PVs and a true ablation failure in three right‐sided PVs. After continued PVAC ablation, 103 of 106 PVs (97%) and 25 of 27 patients (93%) were shown to be isolated. The total procedural time from femoral vein access to complete catheter withdrawal was 176 ± 25 minutes. The actual dwelling‐time of the PVAC within the left atrium was 102 ± 37 minutes. Esophageal T° rise to >38.5° occurred in nine of 19 monitored patients (47%). Conclusions: (1) PVAC‐guided ablation (i.e., mapping and ablation with a single catheter) results in isolation of all PVs in 73% of the patients. (2) An additional circular mapping catheter is required to increase complete isolation rate to 93% of the patients. (3) Given the esophageal T° rise in almost 50% of patients, safety precautions are needed. (PACE 2010; 33:168–178)     

Anatomy of the Left Atrium for Interventional Electrophysiologists

Increasingly, interventional procedures require accessing the left atrium from the inside of the heart as well as from the pericardial space. The right phrenic nerve running along the fibrous pericardium is close to the atrial insertion of the right superior pulmonary vein while the left phrenic nerve passes over the left atrial appendage. Posteriorly, the esophagus descends adjacent to the fibrous pericardium covering the posterior and postero‐inferior walls of the left atrium. The component parts of the left atrium are reviewed with emphasis on the structure of the atrial septum, the left atrial ridge, the mitral isthmus, and the left atrial walls. Although the atrial walls are mainly smooth, pits and crevices are common in the region of the mitral isthmus and the vicinity of the os of the atrial appendage. The muscular rim around the valve of the oval fossa delimits the extent of the true atrial septum. Interatrial muscular connections exist at the septum, along Bachmann's bundle and also at the muscular sleeves of the coronary sinus and pulmonary veins. Anatomical features relevant to interventional electrophysiologists are highlighted. (PACE 2010; 620–627)     

The Importance of Bidirectional Block during Pulmonary Vein Isolation

The definition of a successful ablation of atrial fibrillation can vary among electrophysiologists. A commonly described endpoint is bidirectional block of the four pulmonary veins. A case is described in which entrance block into a pulmonary vein was achieved early during pulmonary vein isolation. However, triggers from the pulmonary vein continued to conduct into the atrium, revealing the block was only unidirectional. Further ablation resulted in true electrical isolation and highlights the importance of achieving bidirectional block. (PACE 2013; 36:e143–e145)     

Focal Ablation versus Single Vein Isolation for Atrial Tachycardia Originating from a Pulmonary Vein

Background: Rapid, disorganized firing from a pulmonary vein (PV) focus may initiate atrial fibrillation. The natural history of PV atrial tachycardia (AT), resulting in a slower, more organized form of firing, is less clear. Furthermore, the optimal therapeutic approach to a PV AT is poorly defined. Objective: This study assessed the characteristics and long‐term outcomes of focal ablation versus PV isolation for ATs arising from a single PV. Methods: We reviewed 886 consecutive patients who underwent an AT radiofrequency ablation at our institution from January 1997 through August 2008. Results: Twenty‐six patients had focal AT with a mean cycle length of 364 ± 90 ms that arose from within a single PV. Ten patients underwent focal ablation of their AT and 16 patients underwent PV isolation of the culprit vein. All procedures were acutely successful. The average follow‐up was 25 months (range 2–90 months). There were three recurrences of AT in patients who underwent a focal ablation. There were no recurrences in patients who underwent targeted PV isolation (P = 0.046). No patients developed atrial fibrillation or AT from another focus during the follow‐up period. Conclusion: PV AT can be successfully treated with single vein isolation or focal ablation with a low risk of recurrence or the development of atrial fibrillation. PV isolation may be the preferred approach when the AT focus arises from a site distal to the ostium where targeted ablation could result in phrenic nerve injury or occlusion of a pulmonary venous branch. (PACE 2010; 776–783)     

Lead aVL P‐Wave Polarity: Insight from Mapping and Ablation of Atrial Arrhythmia Initiated from Superior Vena Cava

We report a case of focal atrial tachycardia (AT) originating from prior superior vena cava isolation line. The P‐wave morphology in lead aVL during the AT differed from that during sinus rhythm although their foci were in close proximity to each other. We discuss the mechanism based on the activation maps of the right atrium. (PACE 2010; 33:e100–e101)     

A Wide Complex Tachycardia with Changing Atrial Activation Sequence

Change of the retrograde atrial activation sequence during radiofrequency (RF) ablation of left‐side accessory pathway can be due to another accessory pathway, another mechanism for the tachycardia, or due to intraatrial conduction block, partial or complete, caused by RF delivery to a site proximal to the site of insertion of the accessory pathway. In this case report, a temporary complete intraatrial conduction block was created by RF delivery proximal to the site of accessory pathway insertion, causing a change in the retrograde atrial activation sequence during ongoing tachycardia that was terminated by ablation at the insertion site of accessory pathway. (PACE 2013; 36:e23–e26)     

Atrial Electromechanical Sequence and Contraction Synchrony during Single- and Multisite Atrial Pacing in Patients with Brady-Tachycardia Syndrome

Objectives: Investigation of which atrial pacing modality provides atrial synchrony and the most physiological atrial contraction pattern in patients with brady-tachycardia syndrome.
Methods: Fifteen healthy subjects and 57 patients with sinus node dysfunction, atrial fibrillation recurrences, and prolonged P-wave on the electrocardiogram treated with multisite atrial (MSA) pacing were studied. One atrial lead was implanted in the coronary sinus (CS) ostium area, the other at the right atrial appendage (RAA): RAA+CS group (28 patients), or Bachmann's bundle (BB) region: BB+CS group (29). Sinus rhythm (SR) and CS, RAA, BB, RAA+CS, and BB+CS pacing modalities were evaluated. Electromechanical delay (EMD) in atrial walls was assessed by tissue Doppler echocardiography. Interatrial (ΔinterA), intra-right (ΔRA), and intra-left (ΔLA) atrial dyssynchrony were calculated.
Results: During SR, in the study group versus controls, important ΔinterA: 55 ± 23 versus 22 ± 11 ms (P < 0.01) and ΔLA: 47 ± 21 versus 21 ± 6 ms (P < 0.001) were present. Single-site BB and both MSA pacing modes restored ΔinterA and ΔLA (ΔinterA: 24 ± 16, 20 ± 13 and 14 ± 9 ms, ΔLA: 28 ± 18, 28 ± 13 and 20 ± 10 ms during BB, RAA+CS and BB+CS pacing, respectively). CS pacing prolonged lateral RA EMD, while RAA pacing LA walls EMD, which resulted in ΔinterA persistence. CS pacing induced ΔRA (50 ± 23 vs 16 ± 8 ms, P < 0.0001 vs controls). Atrial contraction sequence during BB pacing resembled that observed in controls.
Conclusions: (1) Single-site BB and both MSA pacing modes restored atrial synchrony. (2) Single-site RAA and CS ostium pacing retained interatrial dyssynchrony; moreover, CS pacing created RA dyssynchrony. (3) Single-site BB pacing provided physiological atrial contraction sequence.     

Catheter ablation of atrial fibrillation using the Navx-/Ensite-system and a CT-/MRI-guided approach

Background  Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug refractory atrial fibrillation. However, catheter ablation of atrial fibrillation is still a challenge. This is partially due to the high degree of variability with regard to the individual anatomy. Nevertheless, 3D imaging systems (CT, MRI) provide detailed information about the individual left atrial and pulmonary vein morphology. A 3D CT or MRI reconstruction of the left atrium can be displayed in the Navx-/Ensite-system in a synchronised way during the ablation procedure, thereby facilitating the intervention. This study summarizes our preliminary experience with different strategies of AF ablation using the Navx-/Ensite-system and a CT-/MRI-guided approach. Methods  In a total of 41 patients, cardiac MRI (n = 7) or multi-detector spiral computed tomography (n = 34) was performed prior to an ablation procedure. Catheter ablation was performed for paroxysmal atrial fibrillation in 31 patients and for persistent atrial fibrillation in 10 patients. A 3D MRI or high resolution spiral CT data acquisition was performed and a surface rendered model of the LA was created. This model was displayed in the Navx-/Ensite-system throughout the ablation procedure. Results  Catheter ablation was performed using the Navx-system (n = 38) or the Ensite-system (n = 3). Three strategies were used depending on the type of atrial fibrillation: segmental isolation of the pulmonary veins (facilitated by a 3D real-time visualization of the ablation catheter and a circumferential mapping catheter; group A: 20 patients), linear lesions (group C: 3 patients) and a combined approach (group B; 18 patients). The CT-/MRI-models provided an excellent overview over the pulmonary veins and the left atrial appendage. They revealed a high degree of variability with regard to the individual anatomy (e.g. dimensions of the left atrial appendage, pulmonary vein ostia). The CT scans provided a more detailed reconstruction of the left atrial anatomy than the MRI scans (especially in patients who were in atrial fibrillation at the time of the data acquisition). In some patients, the CT-/MRI-models revealed a very small diameter of some pulmonary veins or side branches close to the ostium (e.g. right inferior pulmonary vein). Therefore, no attempt was made to achieve complete pulmonary vein isolation in some patients. In group A, 16/20 (80%) patients had no arrhythmia recurrence [mean follow-up 359 days (SD ± 317 days)]. Twelve out of eighteen (67%) patients in group B [mean follow-up 452 days (SD ± 311 days)] and 2/3 (67%) patients in group C did not experience an arrhythmia recurrence [mean follow-up 1,000 days (SD ± 34 days)]. There were no major complications. Conclusions  The information derived from 3D CT- or MRI-reconstructions facilitates AF ablations performed with the Navx-/Ensite-mapping system and enhances the safety of these procedures. Furthermore, the availability of an additional impedance-based 3D real-time visualization of the ablation catheter and the circular mapping catheter placed in the pulmonary veins represents a major advantage of the Navx system.     

Persistent Atrial Fibrillation Converts to Common Type Atrial Flutter during CFAE Ablation

Background: Catheter ablation of persistent and long‐standing persistent atrial fibrillation (AF) is still challenging. So far different ablation techniques have been reported, including pulmonary vein isolation, additional linear lesions, ablation of complex fractionated atrial electrograms (CFAE), and combinations of these techniques. During ablation of CFAE, the occurrence of left atrial (LA) tachycardia is well known. The occurrence of right atrial flutter on the other hand is less well described. Methods: Here, we report three patients who had been ablated because of symptomatic persistent atrial fibrillation. Summary: In all patients, AF changed into a cavotricuspid isthmus = dependent right atrial flutter during ablation of CFAE in the LA. (PACE 2010; 33:304–308)     

Importance of Superior Vena Cava Isolation in Successful Ablation of Persistent Atrial Fibrillation in Patient with Partial Anomalous Pulmonary Vein

Ectopic foci arising from pulmonary veins (PVs) are the predominant sources for the initiation and maintenance of atrial fibrillation (AF) in a vast majority of cases. However, ectopic foci also exist in the non‐PV areas like superior vena cava (SVC) in 10–20% of the cases. We report the significance of SVC isolation in a patient with persistent AF and anomalous pulmonary venous connection of the right superior pulmonary vein into the SVC. (PACE 2013; 36:e146–e149)     

Nonuniformity of AH Intervals During Stimulation at Different Left Atrial Sites

Studies in humans have found left atrial stimulation via the coronary sinus (CS) to elicit significantly shorter atrium-His (AH) intervals as compared to right atrial stimulation, but whether pacing at dijferent left atrial sites (anterior vs posterior left atrium, i.e., far distal vs proximal CSJ affects the AH interval has not been studied. Hence, in 22 patients, we compared the effects of stimulation from various atriai sites, including anterior high right atrium (HRA), distal CS, mid-CS, and proximal CS, on; stimulus-atrium (SA), AH, and stimuIus-His intervals on the His bundle electrogram. Paced cycle length differed for each patient (range 900–350 msec, mean 532 ± 140 msec), but conduction intervals from different atrial sites were compared using identical cycle length in each patient. The mean SA intervals were 34 ± 10 msec, 57 ± 10 msec, 44 ± 11 msec, and 32 ± 8 msec with stimulation, respectively, from HRA, distal CS, mid-CS. and proximal CS (each significantly different except for HRA vs proximal CSJ. The mean AH intervals were 123 ± 23 msec, 104 ± 28 msec, 95 ± 15 msec, and 90 ± 18 msec with stimulation, respectively, from HRA, distal CS, mid-CS, and proximal CS (each significantly different except for mid-CS vs proximal CSJ. In 13 patients, the discrepancy in AH intervals during distal versus proximal CS stimulation was > 15 msec; in 9 patients this difference was only < 10 msec, considered within the range of measurement error. Thus, in a significant portion of patients, discrepant AH intervals were demonstrated during stimulation from the distal versus proximal CS. These previously undescribed observations suggest that electrophysiological studies on atrioventricular nodal conduction that involve left atrial stimulation must take into account actual location of the stimulation site (anterior or posterior) in order to properly interpret the findings.     

Quantification of atrial tachyarrhythmia burden with an implantable pacemaker before and after pulmonary vein isolation

Long-term efficacy of pulmonary vein (PV) ostial isolation for paroxysmal atrial fibrillation is difficult to assess. We evaluated the net duration of atrial tachyarrhythmia episodes (burden), atrial tachyarrhythmia episode frequency, and quality-of-life (QOL) before and after PV isolation in patients with an existing pacemaker featuring extensive diagnostic capabilities. Due to frequent recurrences of paroxysmal atrial fibrillation, PV isolation was performed 21 +/- 10 months following pacemaker implantation on 12 patients (57 +/- 5 years) with normal left ventricular function. Atrial tachyarrhythmia burden (ATB) and episode frequency were monitored daily by the device both pre- and postablation. QOL questionnaires were collected at ablation and 1, 3, and 6 months thereafter. Patients were followed for 20 +/- 9 and 11 +/- 9 months pre- and postablation, respectively. Membrane-active antiarrhythmic medications were discontinued after ablation in 8 of 12 patients. PV isolation resulted in a significant reduction of ATB from a median of 3.2 hours/day (preablation) to 0.2 hours/day (postablation, P < 0.01, Wilcoxon signed-rank test). The median tachyarrhythmia frequency was 6.4 episodes/day (preablation) and 0.3 episodes/day (postablation, P = 0.09). QOL measures significantly improved over the data collection intervals (P < 0.05). Tachyarrhythmia burden was positively associated with Symptom Checklist frequency and severity (P < 0.01). Significant long-term reductions in total ATB (symptomatic and asymptomatic) were observed. Furthermore, reductions in ATB were associated with improvements in QOL measures. Extensive monitoring capabilities in implantable devices help provide complete disclosure on the effect of PV isolation in paroxysmal atrial fibrillation patients.     

Transseptal left ventricular endocardial pacing reduces dispersion of ventricular repolarization

Background: Cardiac resynchronization therapy (CRT) may be proarrhythmic in some patients. This may be due to the effect of left ventricular (LV) epicardial pacing on ventricular repolarization. The purpose of this study was to evaluate the effect of endocardial versus epicardial LV biventricular pacing on surface electrocardiogram (ECG) parameters that are known markers of arrhythmogenic repolarization. Methods: ECG markers of repolarization (QT dispersion, QTD; T peak to end, T_peak‐end; T_peak‐end dispersion, T_peak‐endD; QTc) were retrospectively measured before and after CRT in seven patients with transseptal LV endocardial leads (TS group), 28 matched patients with coronary sinus (CS) LV leads (CS group), and eight patients with surgical LV epicardial leads (SUR group). All ECGs were scanned and analyzed using digital callipers. Results: Compared to the CS group, the TS group CRT was associated with a significant postpacing reduction in QTD (?45.2 ± 35.6 vs ?4.3 ± 43.6 ms, P = 0.03) and T_peak‐end (?24.2 ± 22.1 vs 3.4 ± 26.7 ms, P = 0.02). There was a nonsignificant post‐CRT reduction in both T_peak‐endD (?11.3 ± 31.0 vs 2.4 ± 28.9 ms, P = 0.27) and QTc (?50.0 ± 46.4 vs 4.4 ± 70.2 ms, P = 0.06) in the TS versus the CS group. In contrast, there were no differences between the SUR and CS groups in terms of the effect of CRT on these repolarization parameters. Conclusions: CRT with (atrial transseptal) endocardial LV lead placement is associated with repolarization characteristics that are considered to be less arrhythmogenic than those generated by CS (epicardial) LV lead placement. Further work is needed to determine whether these changes translate to a reduction in proarrhythmia. (PACE 2011; 34:1258–1266)