Yu An Ding

Initiation of Atrial Fibrillation by Ectopic Beats Originating From the Superior Vena Cava Electrophysiological Characteristics and Results of Radiofrequency Ablation

BACKGROUNDnThe superior vena cava (SVC) has cardiac musculature extending from the right atrium. However, no previous study in humans has given details regarding the ectopic foci that initiate paroxysmal atrial fibrillation (PAF), which may originate from the SVC.nnnMETHODS AND RESULTSnA total of 130 patients with frequent attacks of PAF initiated by ectopic beats were included. Eight patients (6%) had spontaneous AF initiated by a burst of rapid ectopic beats from the SVC (located 19+/-7 mm above the junction of the SVC and right atrium), which was confirmed by multiplane angiographic and intracardiac echocardiographic visualization and was marked by a sharp SVC potential preceding atrial activity. During initial repetitive discharges, the group with SVC ectopy had a higher incidence of intravenous conduction block than the group with pulmonary vein ectopy (75% versus 37%; P=0.03). The activation time of the earliest intracardiac ectopic activities relative to ectopic P wave onset was significantly shorter in the SVC ectopy than the pulmonary vein ectopy group (37+/-15 versus 84+/-32 ms; P<0. 001). After 5+/-3 applications of radiofrequency energy, AF was eliminated. SVC angiography after ablation revealed a local indentation of the venous wall in one patient. Two patients manifested coexisting sinus rhythm and a focal fibrillating activity confined inside the SVC after radiofrequency ablation. During a follow-up period of 9+/-3 months, all 8 patients were free of antiarrhythmic drugs, without tachycardia recurrence or symptoms of SVC obstruction.nnnCONCLUSIONSnEctopic beats initiating PAF can originate from the SVC. A radiofrequency current delivered to eliminate these ectopies is a highly effective and safe way to prevent PAF.

Noncontact three-dimensional mapping and ablation of upper loop re-entry originating in the right atrium

OBJECTIVESnThis study was aimed at delineating the reentrant circuit of right atrial (RA) upper loop re-entry using noncontact three-dimensional mapping.nnnBACKGROUNDnVarious forms of atypical atrial flutter including lower loop re-entry and left atrial flutter have been demonstrated. However, little is known about upper loop re-entry in the RA.nnnMETHODSnThe study population consisted of eight patients (65 +/- 12 years, seven men) with atypical atrial flutter. Right atrial activation during atrial flutter was visualized using a noncontact mapping system (EnSite-3000 with Clarity Software, St. Paul, Minnesota) for a three-dimensional reconstruction of the endocardial depolarization. The narrowest part of the re-entrant circuit was targeted using radiofrequency catheter ablation.nnnRESULTSnNoncontact mapping showed macro-re-entry confined to the RA free wall with RA activation time accounting for 100% of the cycle length (214 +/- 21 ms) in all eight patients. Two patients had counterclockwise activation, and six patients had clockwise activation around the central obstacle, which was composed of the crista terminalis, the area of functional block, and superior vena cava. The lower turn-around points were located at the conduction gap in the crista terminalis. Radiofrequency linear ablation of the conduction gap in the crista terminalis was performed and eliminated atrial flutter in six patients without recurrence during a follow-up of 3.2 +/- 1.1 months.nnnCONCLUSIONSnAtypical atrial flutter could arise from upper loop re-entry in the RA with conduction through the gap in the crista terminalis. Radiofrequency linear ablation of the conduction gap was effective in eliminating this atrial arrhythmia.

Effect of phenylephrine on focal atrial fibrillation originating in the pulmonary veins and superior vena cava

OBJECTIVESnThis study was aimed at evaluating the effects of phenylephrine infusion on the occurrence of focal atrial fibrillation (AF).nnnBACKGROUNDnParoxysmal AF can be initiated by ectopic atrial beats originating in the pulmonary vein (PV) or superior vena cava (SVC). The effect of change in autonomic tone on this focal AF is unknown.nnnMETHODSnThis study included 12 patients with frequent bursts of AF documented by 24-h Holter monitoring. The number and coupling interval of spontaneous ectopic activity and bursts of AF were evaluated for 1 min before and after phenylephrine (2 to 3 microg/kg) injection.nnnRESULTSnAfter detailed mapping, four patients had a focus located in the left superior PV, six in the right superior PV and two in the SVC. In 10 patients with AF foci originating in the PVs, the frequency of ectopic activity (19.5 +/- 27.4 vs. 11.4 +/- 22.9 beats/min, p = 0.059) was reduced as well as AF bursts (14 +/- 3 vs. 1.8 +/- 2.7 bursts/min, p = 0.005) before versus after phenylephrine injection; the minimal coupling interval of ectopic activity and AF bursts became longer compared with baseline. The maximal percent increase in sinus cycle length after phenylephrine injection was significantly greater in patients with complete suppression of AF compared with those with partial suppression (43 +/- 19 vs. 14 +/- 5%, p = 0.01). However, no significant effect of phenylephrine on AF originating in the SVC was found.nnnCONCLUSIONSnChange in autonomic tone induced by phenylephrine injection was effective in suppressing focal AF originating in the PVs but not in the SVC.

Differentiating the ligament of marshall from the pulmonary vein musculature potentials in patients with paroxysmal atrial fibrillation: Electrophysiological characteristics and results of radiofrequency ablation

TAI, C.‐T., et al.: Differentiating the Ligament of Marshall from the Pulmonary Vein Musculature Potentials in Patients with Paroxysmal Atrial Fibrillation: Electrophysiological Characteristics and Results of Radiofrequency Ablation. It was reported that paroxysmal atrial fibrillation (PAF) can be initiated by ectopic atrial beats originating from the pulmonary vein (PV) or left atrial tract (LAT) within the ligament of Marshall (LOM). The aim of this study was to differentiate the LAT from the PV potentials, and to investigate the results of radiofrequency ablation guided by these potentials. Ten patients (age 60 ± 12 years) with PAF who had a recording of double potentials (DPs) in or around the left PV were included. Group I had five patients with the second deflection of DPs (D2) due to activation of the LAT, and Group II had five patients with D2 due to activation of the PV musculature. There were no significant difference in the isoelectric interval between DPs, the activation time, and amplitude of D2 between Groups I and II. During distal coronary sinus (CS) pacing, the CS ostium (CSO) to D2 interval was shorter compared with that during sinus rhythm in Group I (39 ± 19 vs 71 ± 25 ms, P = 0.04), but was longer in Group II (96 ± 16 vs 44 ± 19 ms, P = 0.04). During ectopic activation, three patients in Group I, but no Group II patients, had transformation of recorded DPs into triple potentials. Radiofrequency ablation guided by the earliest activation of the LAT potential was performed with transient suppression of PAF, but ablation guided by the earliest activation of the PV potentials had a high success rate in eliminating PAF. In conclusion, differentiating the LAT from the PV potentials for initiation of PAF is feasible by an electrophysiological approach, and may be important for radiofrequency ablation of PAF.

Double Potential Interval and Transisthmus Conduction Time for Prediction of Cavotricuspid Isthmus Block after Ablation of Typical Atrial Flutter

AbstractBackground: Complete bi-directional isthmus block is the endpoint of typical atrial flutter ablation. The purpose of this study was to investigate the feasibility of the local double potential (DP) interval and the change in transisthmus conduction time for predicting complete isthmus block after ablation of the cavotricuspid isthmus.nMethods: The study population consisted of 32 patients with typical atrial flutter after a procedure of radiofrequency (RF) ablation of the cavotricuspid isthmus (16 had incomplete block and 16 had complete block). The transisthmus conduction time was determined during pacing from the proximal coronary sinus and low lateral right atrium before and after RF ablation. The DP interval close to the ablation line was evaluated after final RF energy application.nResults: In the counterclockwise direction, transisthmus conduction time had an increase of 37 ± 25.4% and 127.3 ± 35.5% (P < 0.001), and the DP interval was 63.3 ± 8.7 ms and 120 ± 17.4 ms (P < 0.001) after achievement of incomplete and complete block, respectively. The sensitivity, specificity, positive and negative predictive values of an increase in the transisthmus conduction time ≥50% were 100%, 81%, 84% and 100%, respectively; those of DP interval ≥100 ms were 100%. In the clockwise direction, transisthmus conduction time had an increase of 38.8 ± 28.6% and 135.7 ± 63.6% (P < 0.001), and the DP interval was 63.6 ± 13.8 ms and 127.7 ± 27.1 ms (P < 0.001) after achievement of incomplete and complete block, respectively. The sensitivity, specificity, positive and negative predictive values of an increase in the transisthmus conduction time ≥50% were 100%, 67%, 83% and 100%, respectively; those of the DP interval ≥100 ms were 100%.nConclusions: The transisthmus conduction time ≥50% increase or DP interval ≥100 ms was feasible to predict complete bi-directional isthmus block.

Electrophysiological Mechanisms and Catheter Ablation of Complex Atrial Arrhythmias from Crista Terminalis

Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 ± 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow‐up of 9 ± 5 months (range 5–18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy‐initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.

Novel concept of atrial tachyarrhythmias originating from the superior vena cava: insight from noncontact mapping.

Introduction: Information about the activation patterns inside the superior vena cava (SVC) and entry and exit sites at the SVC‐right atrial (RA) junction during SVC tachyarrhythmia is limited.

Conduction properties of the crista terminalis in patients with atrial flutter due to amiodarone therapy for atrial fibrillation

Some patients with atrial fibrillation (AF) treated by antiarrhythmic drugs (AAD) can develop typical atrial flutter, but the mechanism is not clear. This study included 21 patients with AF. Group I (n = 7) had typical atrial flutter due to amiodarone therapy. Group II (n = 7) did not develop atrial flutter after amiodarone treatment. Group III (n = 7) did not receive AAD treatment. A 7 Fr, 20‐pole electrode catheter was placed along the CT identified by fluoroscopy and intracardiac echocardiography. After restoration of the sinus rhythm, decremental pacing near the CT was performed until 2 to 1 atrial capture. Complete transverse conduction block was defined as the appearance of double potentials with opposite activation sequence along the CT. Focal transverse conduction delay was defined as the appearance of double potentials at ≥ 2 recording sites. Focal transverse conduction delay was observed during pacing at the cycle length of 693 ± 110 ms in group I, 360 ± 97 ms in group II and 343 ± 109 ms in group III (P = 0.001). Complete transverse conduction block was observed during pacing at the cycle length of 391 ± 118 ms in group I and 231 ± 23 ms in group II (P = 0.001), but not in group III. In conclusion, focal transverse conduction delay in the CT was common in patients with AF. A predisposition to the line of the conduction block in the CT might contribute to the conversion of AF to typical atrial flutter due to amiodarone therapy. (PACE 2003; 26:2241–2246)

Use of fluoroscopic views for detecting Marshall's vein in patients with cardiac arrhythmias.

AbstractIntroduction: Recently, several studies showed that focal atrial fibrillation (AF) can be initiated by ectopic beats from the vein of Marshall (VOM). However, the incidence and best fluoroscopic views of VOM have never been reported.nMethods and Results: 106 patients (Non-AF = 52, AF = 54) underwent balloon-occluded coronary sinus angiography using seven fluoroscopic views (PA, Lateral, RAO 30°, RA 30° + Caudal 20°, LAO 30°, LAO 60°, LAO 60° + Cranial 20°). The total incidence of VOM was 74.5% (79/106), without significant difference in age (81.1 vs. 71.0%, >65 vs. ≤65 yrs, p = 0.257) and sex (male vs. female = 72.7 vs. 77.5%, p = 0.585). Furthermore, similar incidence of VOM was noted in patients with Non-AF (71.2%) and AF group (77.8%, p = 0.434). The RAO 30° fluoroscopic view can demonstrate all the left atrial veins and VOM. However, only the LAO 30° fluoroscopic view could confirm VOM and differentiate it from left atrial veins (after vs. before junction of coronary sinus and great cardiac vein, respectively).nConclusion: VOM was equally distributed in patients with different arrhythmias, and the appropriate fluoroscopic view was important for the differential diagnosis of VOM and left atrial veins.

Mapping Techniques in Patients with Paroxysmal Atrial Fibrillation Originating from the Pulmonary Vein

The so-called paroxysmal atrial fibrillation (AF) could be initiated by ectopic beats originating from the superior vena cava, cristal terminalis, ostium of coronary sinus, interatrial septum, atrial free wall, or ligament of Marshall; but most of the ectopic beats originate from the orifices of pulmonary veins (PVs) or from the myocardial sleeves inside the PVs.1–9 Several laboratories have demonstrated that RF catheter ablation could effectively eliminate this type of AF, and suggest that AF is initiated by ectopic beats from a critical focus.1–9 This article will discuss several critical issues regarding the mapping technique and interpretation of intracardiac electrograms in AF initiated by PV ectopic beats.