High resolution mapping of the pulmonary vein and the vein of Marshall during induced atrial fibrillation and atrial tachycardia in a canine model of pacing-induced congestive heart failure

OBJECTIVES: The study examined the activations in the pulmonary veins (PVs) and the vein of Marshall (VOM) during atrial fibrillation (AF) in dogs with congestive heart failure (CHF). BACKGROUND: The patterns of activation within the PVs and the VOM during AF in CHF are unclear. METHODS: We induced CHF in nine dogs by rapid ventricular pacing. The patterns of activation during induced AF were studied one week after ceasing ventricular pacing. RESULTS: The duration of induced AF averaged 80.7 +/- 177.3 s. The termination of low-amplitude fractionated activity in the PVs preceded the termination of AF in 25 of 29 episodes. High-density mapping (1-mm resolution) showed that the PV was activated by a focal wave front independent of left atrial (LA) activation in 22 AF episodes. Frequent intra-PV conduction blocks and multiple wave fronts in the PVs were recorded during 10 AF episodes. Focal activations were observed within the VOM in 4 of 12 episodes of AF. Three atrial tachycardia (AT) episodes originated from a focus within a PV. Histological studies showed extensive fibrosis in the PVs and in the atria. The PVs in five normal dogs did not have focal or fractionated activity during induced AF. CONCLUSIONS: Atrial fibrillation in canine CHF is associated with independent focal activations in the PVs and the VOM, and with complex wave fronts within the PVs. The PVs may also serve as the origin of AT. These findings suggest that electrical and anatomical remodeling of the PVs and the VOM are important in the maintenance of AF and AT in dogs with CHF.     

Pulmonary vein electrogram characteristics in patients with focal sources of paroxysmal atrial fibrillation

INTRODUCTION: The major source of ectopic beats initiating paroxysmal atrial fibrillation (AF) is from pulmonary veins (PVs). However, the electrogram characteristics of PVs are not well defined. METHODS AND RESULTS: Group I consisted of 129 patients with paroxysmal AF. Group II consisted of 10 patients with a concealed left-sided free-wall accessory pathway. All group I patients had spontaneous AF initiated by ectopic beats, including 169 ectopic foci originating from the PVs. We analyzed PV electrograms from the 169 ectopic foci during sinus beats and ectopic beats. During AF initiation, most (70%) ectopic beats showed PV spike potential followed by atrial potential; 16% of ectopic beats showed PV fragmented potential followed by atrial potential; and 14% showed fusion potentials. The coupling interval between the sinus beat and the ectopic beat was significantly shorter in the inferior PVs than in the superior PVs (171 +/- 48 msec vs 222 +/- 63 msec, P = 0.001) and was significantly shorter in the distal foci than in the ostial foci of PVs (206 +/- 52 msec vs 230 +/- 56 msec, P = 0.01). The incidence of conduction block in the PVs during AF initiation was significantly higher in the inferior PVs than in the superior PVs (12/24 vs 37/145, P = 0.03) and was significantly higher in the distal foci than in the ostial foci of PVs (43/121 vs 6/48, P = 0.04). The maximal amplitude of PV potential was significantly larger in the left PVs than in the right PVs, and the maximal duration of PV potential was significantly longer in the superior PVs than in the inferior PVs during sinus beats in both group I and II patients. CONCLUSION: PV electrogram characteristics were different among the four PVs. Detailed mapping and careful interpretation are the most important steps in ablation of paroxysmal AF originating from PVs.     

经导管射频消融治疗起源于肺静脉的心房颤动(附二例报告)

报道 2例经射频消融治疗成功的起源点位于肺静脉的心房颤动 (简称房颤 ) ,均伴有频发房性早搏 (简称房早 )的阵发性房颤。电生理检查时行两次房间隔穿刺 ,将两根 10极标测导管通过长鞘送入左、右上肺静脉 ,选择性肺静脉造影证实肺静脉开口部位。静脉滴注异丙肾上腺素后 1例诱发出频发房早 ,另 1例诱发出频发房早及房颤 ,且房早及房颤开始发作时的心内电图均显示最早心房激动点位于右上肺静脉内 ,其局部电位分别较体表心电图异位 P波的起点提前 61和 96ms。在最早心房激动点处以 15～ 2 0 W的输出功率消融 60～ 180 s后房早及房颤消失 ,静脉滴注异丙肾上腺素亦未再诱发房颤。术后随访 8～ 12个月 ,房颤无复发。结论 :射频消融治疗起源于肺静脉的房颤效果较好且相对安全 ;在这类患者应用两根多极导管同步标测双上肺静脉是一种有效的标测和消融方法。     

A single pulmonary vein as electrophysiological substrate of paroxysmal atrial fibrillation

Introduction: It has been demonstrated that pulmonary veins (PVs) play an important role in initiation and maintenance of paroxysmal atrial fibrillation (AF). However, it is not clearly known whether a single PV acts as electrophysiological substrate for paroxysmal AF.
Methods and Results: This study included five patients with paroxysmal AF. All patients underwent complete PV isolation with continuous circular lesions (CCLs) around the ipsilateral PVs guided by a three-dimensional mapping system. Irrigated radiofrequency (RF) delivery was performed during AF on the right-sided CCLs in two patients and on the left-sided CCLs in three patients. The incomplete CCLs resulted in a change from AF to atrial tachycardia (AT), which presented with an identical atrial activation sequence and P wave morphology. Complete CCLs resulted in AF termination with persistent PV tachyarrhythmias within the isolated PV in all five patients. PV tachyarrhythmia within the isolated PV was PV fibrillation from the left common PV (LCPV) in two patients, PV tachycardia from the right superior PV (RSPV) in two patients, and from the left superior PV in one patient. All sustained PV tachyarrhythmias persisted for more than 30 minutes, needed external cardioversion for termination in four patients and a focal ablation in one patient. After the initial procedure, an AT from the RSPV occurred in a patient with PV fibrillation within the LCPV, and was successfully ablated.
Conclusion: In patients with paroxysmal AF, sustained PV tachyarrhythmias from a single PV can perpetuate AF. Complete isolation of all PV may provide good clinical outcome during long-term follow-up.     

Paroxysmal cycle length shortening in the pulmonary veins during atrial fibrillation correlates with arrhythmogenic triggering foci in sinus rhythm

INTRODUCTION: The focal origin of atrial fibrillation (AF) is identified by recording atrial ectopic beats or the ectopic activity that precedes AF. We hypothesized that arrhythmogenic pulmonary veins (PVs) also could be identified during persistent AF. METHODS AND RESULTS: Patients with persistent AF referred for focal ablation were enrolled prospectively. During AF, bipolar electrograms were recorded from each PV for a minimum of 120 seconds, as well as from the right atrium and coronary sinus. The cycle length of activity in each PV was measured during AF and plotted on a frequency histogram. Following cardioversion to sinus rhythm, arrhythmogenic PVs were identified from reinitiation of AF or from ectopic beats. Ten patients were enrolled and 37 PVs analyzed. During AF, 17 PVs demonstrated bimodal cycle length frequency histograms, with periods of paroxysmal short cycle length recording. Following cardioversion, 14 PVs were identified as arrhythmogenic as defined earlier. Each of these arrhythmogenic PVs showed paroxysmal short cycle length recording during AF. Sensitivity was 87%, specificity 91%, positive predictive value 87%, and negative predictive value 100%. CONCLUSION: The arrhythmogenic PVs responsible for the focal activity that triggers AF also demonstrate paroxysmal short cycle length recording during sustained AF. These results demonstrate that arrhythmogenic PVs still can be identified reliably, even during sustained AF.     

Electrophysiologically guided pulmonary vein isolation during sustained atrial fibrillation

INTRODUCTION: Sustained atrial fibrillation (AF) is frequently encountered during pulmonary vein (PV) isolation. The aim of this study was to evaluate the feasibility and safety of PV isolation during sustained AF. METHODS AND RESULTS: Thirty-seven patients (30 men, age 54 +/- 10 years) underwent Lasso-guided isolation of 87 PVs during sustained AF. Baseline PV electrogram patterns were classified into one of two types: organized, with consistent PV activation sequence; or disorganized, with constant variation of PV activation sequence. In disorganized activity, radiofrequency ablation was performed circumferentially around the Lasso while the earliest PV potential was targeted during organized activity. Complete left atrial (LA) to PV block during AF was identified by abolition or dissociation of all sharp potentials recorded within the vein. PV isolation then was verified during sinus rhythm. Baseline activation patterns of PV potential were organized in 32 PVs (37%) [more frequently in inferior veins than superior veins (53% vs 26%, P = 0.01)] and disorganized in 55 PVs (63%). In 59 of 87 PVs, isolation was begun and completed during AF. Radiofrequency ablation organized PV activation sequence in 75% prior to isolation. LA-PV block was confirmed during sinus rhythm in 54 (92%) of 59 PVs. In 28 of 87 PVs, sinus rhythm was restored before complete LA-PV block. Complete isolation was achieved in all 87 PVs without complications. CONCLUSION: PV isolation can be effectively and safely performed during sustained AF, preceded in most cases by organization of PV electrogram activity. This strategy may be the preferred alternative to multiple intraprocedural cardioversions.     

High-density mapping of spontaneous pulmonary vein activity initiating atrial fibrillation in humans

Introduction: High-density three-dimensional (3D) mapping of the pulmonary vein (PV)-left atrial (LA) junction was performed to characterize spontaneous PV activity in humans.
Methods and Results: The activation patterns of ectopic beats and of the initial 2 seconds of atrial fibrillation (AF) from the PVs were analyzed using a 64-poles basket catheter. A focal mechanism was defined as a discrete site of early and centrifugal activation. Continuous activity was considered as an activation covering ≥80% of the tachycardia beat-to-beat cycle length within the mapping field. In 35 patients, 123 spontaneous focal ectopic beats that did not induce AF and 95 that did induce AF were mapped. The mean coupling interval of ectopic discharges not inducing AF was 281 ± 70 msec versus 236 ± 90 msec for ectopies initiating AF (P ≤ 0.01). The first ectopic activity of all 218 arrhythmogenic events showed exclusively a focal mechanism. During the 95 episodes of AF initiation, one or two ectopic beats from the PVs initiated AF in the LA in 39%, a stable focal tachycardia was recorded in 14%, continuous activity with important changes in cycle length (35 ± 15 msec) suggestive of decremental or fibrillatory conduction was found in 18%, and in 29% the activation pattern could not be classified. No stable and sustained reentrant circuit could be identified by our mapping tool in the PV-LA junction.
Conclusions: Arrhythmogenic activity from PVs in humans is predominantly due to discrete focal activity.     

Predicting the arrhythmogenic foci of atrial fibrillation before atrial transseptal procedure: implication for catheter ablation

INTRODUCTION: Use of endocardial atrial activation sequences from recording catheters in the right atrium, His bundle, and coronary sinus to predict the location of initiating foci of atrial fibrillation (AF) before an atrial transseptal procedure has not been reported. The purpose of the present study was to develop an algorithm using endocardial atrial activation sequences to predict the location of initiating foci of AF before transseptal procedure. METHODS AND RESULTS: Seventy-five patients (60 men and 15 women, age 68 +/- 12 years) with frequent episodes of paroxysmal AF were referred for radiofrequency ablation. By retrospective analysis, characteristics of the endocardial atrial activation sequences of right atrial, His-bundle, and coronary sinus catheters from the initial 37 patients were correlated with the location of initiating foci of AF, which were confirmed by successful ablation. The endocardial atrial activation sequences of the other 38 patients were evaluated prospectively to predict the location of initiating foci of AF before transseptal procedure using the algorithm derived from the retrospective analysis. Accuracy of the value <0 msec (obtained by subtracting the time interval between high right atrium and His-bundle atrial activation during atrial premature beats from that obtained during sinus rhythm) for discriminating the superior vena cava or upper portion of the crista terminalis from the pulmonary vein (PV) foci was 100%. When the interval between atrial activation of ostial and distal pairs of the coronary sinus catheter of the atrial premature beats was <0 msec, the accuracy for discriminating left PV foci from right PV foci was 92% in the 24 foci from the left PVs and 100% in the 19 foci from the right PVs. CONCLUSION: Endocardial atrial activation sequences from right atrial, His-bundle, and coronary sinus catheters can accurately predict the location of initiating foci of AF before transseptal procedure. This may facilitate mapping and radiofrequency ablation of paroxysmal AF.     

P wave morphology during spontaneous and paced pulmonary vein activity: differences between patients with atrial fibrillation and normal controls

P wave morphology (PWM) has been used to predict the location of ectopic foci responsible for triggering atrial fibrillation (AF). With bi-atrial mapping, this study examined PWM during spontaneous ectopy and during pulmonary vein (PV) pacing, comparing the results with published algorithms in 40 AF patients and 15 controls. PWM during PV pacing is similar to spontaneous ectopy, if performed at similar coupling intervals. PWM during ectopic activity from the PVs is affected by cycle length and the presence of underlying atrial electrical and structural abnormalities. Changes in PWM during decremental pacing were observed in 5% of controls but in over 25% of persistent AF patients. The algorithms are accurate in over 90% of controls and paroxysmal AF patients with normal atria, but less than 60% in those with persistent AF or electrical or structural atrial abnormalities. The accuracy of non-invasive localization of arrhythmogenic PV is limited.     

Hypertension and hypertensive heart disease are associated with increased ostial pulmonary vein diameter

INTRODUCTION: Atrial fibrillation (AF) is associated with increased ostial pulmonary vein (PV) diameter and commonly with hypertension. We sought to investigate ostial PV anatomy in patients with and without AF with the goal of characterizing the relationship to hypertension and cardiovascular disease. METHODS AND RESULTS: Ostial PV diameter was assessed by preprocedural spiral computed tomography in 100 AF patients undergoing a PV isolation procedure and in 24 age- and sex-matched non-AF control patients. Ostial diameter of 392 PVs in 100 AF patients was increased compared to 106 PVs in 24 non-AF controls (1.50 +/- 0.31 vs 1.20 +/- 0.31 cm, P <0.001) and diameters of individual PVs were uniformly affected (r=0.45-0.62, P <0.001). Left atrial dilation was associated with a larger PV diameter (1.56 +/- 0.32 vs 1.44 +/- 0.29 cm, P <0.01). PV diameter in AF patients with hypertension (1.55 +/- 0.32 cm), particularly if associated with left ventricular hypertrophy (1.66 +/- 0.37 cm), was larger compared to AF patients without hypertension (1.43 +/- 0.26 cm, P <0.01). PV diameter in control patients with hypertension (n=14) was larger than in those without hypertension (n=10, P <0.01). Patients with persistent AF had larger PV diameters (1.61 +/- 0.34 cm) than patients with paroxysmal AF (1.47 +/- 0.30 cm, P <0.01). Male gender (P <0.01), history of hypertension (P <0.01), and persistent AF (P <0.05) were identified as independent cofactors of increased ostial PV diameter. Conclusion: PV dilation affects all PVs uniformly in AF patients. Hypertension and hypertensive heart disease in patients with and without AF are associated with PV dilation, supporting theories that impaired left ventricular diastolic function is associated with a stretch-induced PV arrhythmia mechanism.     

Focal atrial fibrillation: experimental evidence for a pathophysiologic role of the autonomic nervous system

INTRODUCTION: Focal paroxysmal atrial fibrillation (AF) was shown recently to originate in the pulmonary veins (PVs) and superior vena cava (SVC). In the present study, we describe an animal model in which local high-frequency electrical stimulation produces focal atrial activation and AF/AT (atrial tachycardia) with electrogram characteristics consistent with clinical reports. METHODS AND RESULTS: In 21 mongrel dogs, local high-frequency electrical stimulation was performed by delivering trains of electrical stimuli (200 Hz, impulse duration 0.1 msec) to the PVs/SVC during atrial refractoriness. Atrial premature depolarizations (APDs), AT, and AF occurred with increasing high-frequency electrical stimulation voltage. APD/AT/AF originated adjacent to the site of high-frequency electrical stimulation and were inducible in 12 of 12 dogs in the SVC and in 8 of 9 dogs in the left superior PV (left inferior PV: 7/8, right superior PV: 6/8; right inferior PV: 4/8). In the PVs, APDs occurred at 13+/-8 V and AT/AF at 15+/-9 V (P < 0.01; n = 25). In the SVC, APDs were elicited at 19+/-6 V and AT/AF at 26+/-6 V (P < 0.01; n = 12). High-frequency electrical stimulation led to local refractory period shortening in the PVs. The response to high-frequency electrical stimulation was blunted or prevented after beta-receptor blockade and abolished by atropine. In vitro, high-frequency electrical stimulation induced a heterogeneous response, with shortening of the action potential in some cells (from 89+/-35 msec to 60+/-22 msec; P < 0.001; n = 7) but lengthening of the action potential and development of early afterdepolar-izations that triggered APD/AT in other cells. Action potential shortening was abolished by atropine. CONCLUSION: High-frequency electrical stimulation evokes rapid ectopic beats from the PV/SVC, which show variable degrees of conduction block to the atria and induce AF, resembling findings in patients with focal idiopathic paroxysmal AF. The occurrence of the arrhythmia in this animal model was likely due to alterations in local autonomic tone by high-frequency electrical stimulation. Further research is needed to prove absolutely that the observed effects of high-frequency electrical stimulation were caused by autonomic nerve stimulation.     

Role of Right Middle Pulmonary Vein in Patients with Paroxysmal Atrial Fibrillation

INTRODUCTION: Elimination of the ectopic foci from pulmonary veins (PVs) has proved to be a curative therapy for focal atrial fibrillation (AF). However, information about the importance of the right middle PV (RMPV) in initiation of AF and radiofrequency ablation of AF is limited. METHOD AND RESULTS: Forty-three patients (34 men and 9 women; age 65+/-12 years) with drug-refractory paroxysmal AF underwent electrophysiologic study and catheter ablation for treatment of AF. Three-dimensional magnetic resonance angiography (MRA) of the PVs and left atrium (LA) was performed to determine the anatomic patterns of RMPV. Diameter of PV ostium was measured at the junction of the LA and each PV. MRA findings showed the following: (1) 36 (84%) of 43 patients had a discrete RMPV; (2) there are three drainage patterns of RMPV, including joining the proximal part (<1 cm from the ostium) of the right superior PV (RSPV), joining the right inferior PV (RIPV), and a separate RMPV ostium in the LA wall; and (3) the ostial diameter of RMPV was significantly smaller than RSPV and RIPV (P < 0.01). Electrophysiologic studies demonstrated that five AF foci arose from RMPV. The coupling interval between the ectopic beat of AF and sinus beat was longer in RMPV than RSPV (262+/-45 msec vs 212+/-47 msec; P = 0.043). All AFs from RMPV were ablated successfully. PV stenosis or AF recurrence from RMPV was not found during follow-up of 10+/-4 months. CONCLUSION: RMPV was detected by MRA in >80% of paroxysmal AF patients. Ectopy from RMPV can initiate AF, and radiofrequency ablation of RMPV foci is feasible and safe.     

Usefulness of a new radiofrequency thermal balloon catheter for pulmonary vein isolation: a new device for treatment of atrial fibrillation

INTRODUCTION: A rapidly firing or triggered ectopic focus located within a pulmonary vein (PV) or close to the PV ostium could induce atrial fibrillation (AF). The aim of this study was to evaluate the efficacy and safety of a radiofrequency thermal balloon catheter for isolation of the PV from the left atrium (LA). METHODS AND RESULTS: Twenty patients with drug-resistant paroxysmal AF were treated by isolating the superior PVs using an RF thermal balloon catheter. Using a transseptal approach, the balloon, which had an inflated diameter 5 to 10 mm larger than that of the PV ostium, was wedged at the LA-PV junction. It was heated by a very-high-frequency current (13.56 MHZ) applied to the coil electrode inside the balloon for 2 to 3 minutes, and the procedure was repeated up to four times. The balloon center temperature was maintained at 60 degrees to 75 degrees C by regulating generator output. Successful PV isolation was achieved in 19 of the 20 left superior PVs and in all 20 of the right superior PVs and was associated with a decrease in amplitude of the ostial potentials. Total procedure time was 1.8 +/- 0.5 hours, which included 22 +/- 7 minutes of fluoroscopy time. After a follow-up period of 8.1 +/- 0.8 months, 17 patients were free from AF, with 10 not taking any antiarrhythmic drugs and 7 taking the same antiarrhythmic agent as before ablation. Electron beam computed tomography revealed no complications, such as PV stenosis at ablation sites. CONCLUSION: The PV and its ostial region can be safely and quickly isolated from the LA by circumferential ablation around the PV ostia using a radiofrequency thermal balloon catheter for treatment of AF.     

Mechanistic significance of intermittent pulmonary vein tachycardia in patients with atrial fibrillation

INTRODUCTION: The significance of intermittent tachycardia within a pulmonary vein (PV) during an episode of atrial fibrillation (AF) is unclear. The aim of this study was to determine the role that intermittent PV tachycardias play in AF. METHODS AND RESULTS: In 56 patients with AF, segmental ostial ablation guided by PV potentials was performed to isolate the PVs. The characteristics of intermittent PV tachycardias and the inducibility of AF before and after PV isolation were analyzed prospectively. During AF, a PV tachycardia (mean cycle length 130 +/- 30 msec) with exit block to the left atrium was present in 93% of left superior, 80% of left inferior, 73% of right superior, and 7% of right inferior PVs. The site of shortest cycle length during AF alternated between the PVs and left atrium 1 to 13 times per minute. Complete isolation was achieved in 168 (94%) of 178 targeted PVs. In 99% of PVs, tachycardia resolved upon isolation. AF was persistent before and after PV isolation in 100% and 27% of patients, respectively (P < 0.001). CONCLUSION: Intermittent bursts of tachycardia are observed within multiple PVs during persistent AF in a majority of patients. After PV isolation, PV tachycardias almost always resolve, and AF is less likely to be inducible or persistent. These observations suggest a dynamic interplay between the atria and PVs, with intermittent bursts of PV tachycardia being dependent on left atrial input and with the probability of persistent AF diminishing when PV tachycardias are eliminated by PV isolation.     

Electroanatomic characteristics of atrial premature beats triggering atrial fibrillation in patients with persistent versus paroxysmal atrial fibrillation

APBs in Persistent Versus Paroxysmal AF. BACKGROUND: Although the electrical disconnection between the left atrium (LA) and pulmonary veins (PVs) by radiofrequency catheter ablation has been proven to be effective in controlling atrial fibrillation (AF), the recurrence rate is higher in patients with persistent AF (PeAF) than with paroxysmal AF (PAF). We hypothesized that the origin of the atrial premature beats (APBs) that trigger AF and the pattern of their breakthrough into the LA differ between PAF and PeAF. METHODS: We mapped 75 APBs (53 APBs triggering AF, 22 isolated APBs) from the LA and PVs in 26 patients with AF (age: 49.5 +/- 9.6, males: 23, PAF = 17, PeAF = 9), using a noncontact endocardial mapping (NCM) system. The location of the preferential conduction (PC) sites and their conduction velocity (CV) were compared. RESULTS: In patients with PeAF, the earliest activation (EA) site and exit of the PC were more frequently located on the LA side of the LA-PV junction as compared with PAF (P < 0.001). Eighty-one percent of the PCs were located in the area between the left and right superior PVs. The incidence of PCs was similar between the PeAF and PAF patients (P = NS). PCs were more commonly found with APBs inducing AF (63.3%) than with those not inducing AF (35.2%, P = 0.01). The CV of the PC was slower for PeAF than PAF (P < 0.001). The CV in the LA during sinus rhythm was also slower for PeAF than PAF (P < 0.01). CONCLUSION: PeAF was more frequently triggered by APBs from the LA side of the LA-PV junction than PAF and resulted in slower conduction than did PAF. These findings may help explain the higher potential for recurrence after electrical PV isolation in patients with PeAF.     

"Dormant" pulmonary vein conduction revealed by adenosine after ostial radiofrequency catheter ablation

INTRODUCTION: The endogenous nucleoside adenosine is an important intermediate in cellular metabolism, a regulator of function in many organ systems, and a pharmacologic agent with potent electrophysiologic effects. We studied the effects of adenosine on the activation of the pulmonary veins (PVs) after successful ostial isolation in patients with atrial fibrillation (AF). METHODS AND RESULTS: Twenty-nine patients (21 male; mean age 54 +/- 10 years) with refractory highly symptomatic persistent (n = 9) or paroxysmal (n = 20) AF were included in the study. PV isolation was performed using radiofrequency catheter ablation guided by a multipolar basket catheter (Constellation, Boston Scientific). After successful PV isolation, we studied the effects of intravenous adenosine (12-18 mg) on activation of the upper PVs. A total of 83 PVs were successfully isolated. After adenosine, PV activity was recorded in 10 (34%) of 29 left upper PVs studied and in 3 (13%) of 24 right upper PVs, coupled to atrial activity for 20 +/- 7 seconds (adenosine positive). In 8 (62%) of 13 cases, PV potentials were recorded in the distal electrodes of the basket catheter only. Dissociated PV rhythms (N = 8) present after PV isolation disappeared after adenosine for 18 +/- 7 seconds, even if reconduction was missing. In 14 patients (48%), a second EP study was performed for recurrence of AF. Adenosine-positive PVs had a nonsignificant higher rate of recovery of conduction than adenosine-negative veins (71% vs 35%, P = 0.095). CONCLUSION: Adenosine induces transient conduction in 25% of PVs following successful isolation. Further studies are necessary to determine the physiologic or pathophysiologic role of adenosine-induced reconduction in human hearts or other organ systems.     

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

OBJECTIVES: This study was aimed at evaluating the effects of phenylephrine infusion on the occurrence of focal atrial fibrillation (AF). BACKGROUND: Paroxysmal 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. METHODS: This 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. RESULTS: After 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. CONCLUSIONS: Change in autonomic tone induced by phenylephrine injection was effective in suppressing focal AF originating in the PVs but not in the SVC.     

Effects of circumferential ostial radiofrequency lesions on pulmonary vein activation recorded with a multipolar basket catheter

AIMS: Two different ablation procedures are performed to cure patients of atrial fibrillation (AF): (1) the electrophysiological pulmonary vein (PV) isolation, and (2) the anatomical circumferential ablation of all four PV ostia. The aim of this study was to determine the effects of circumferential radiofrequency lesions around the ostia on PV activation. METHODS AND RESULTS: In 34 patients with drug refractory paroxysmal (N = 22) or persistent (N = 12) AF a 31-mm basket catheter (BC) was introduced transseptally in the PVs. After creating a circumferential ablation line around the PV ostia using a nonfluoroscopic 3D-navigation system, electrical isolation was achieved in 46% of the PVs, and prolongation of conduction time (+39 +/- 34 ms) was observed in 30%. PVs with persistent conduction (54%) were isolated by ablating the remaining conduction pathways using the BC. At 12 months follow-up, 62% of the patients were in stable sinus rhythm without antiarrhythmic drug therapy. Six patients had developed left atrial flutter. CONCLUSIONS: Anatomically guided, circumferential lesions around the PV ostia resulted in isolation in only 46% of the veins. At 12 months, 62% of the patients were free of AF without antiarrrhythmic drug treatment, however, 6 patients (18%) developed left atrial flutter.     

Marshall vein as arrhythmogenic source in patients with atrial fibrillation: correlation between its anatomy and electrophysiological findings

Background: Atrial fibrillation (AF) may originate from catecholamine-sensitive vein of Marshall (VOM) or its ligament in addition to pulmonary veins (PVs). The anatomy of VOM and its relation to arrhythmogenic foci in the left atrium are unknown. We studied the anatomy of VOM and its relation to foci in patients with AF.
Methods: The study population consisted of 100 patients with AF (mean age, 62 years; chronic AF, n = 15). AF sources were determined at baseline and after isoproterenol administration without sedation. VOM was identified by balloon-occluded coronary sinus (CS) angiography. We determined its anatomy in relation to left PVs.
Results: VOM was visualized in 73 patients (73%). Ninety-seven patients had 269 arrhythmogenic foci (PV, n = 77; non-PV, n = 48). Non-PV foci included left atrial posterior wall (24, 9%), left lateral area (12, 4.5%), roof (6, 2.2%), superior vena cava (28, 10.4%), crista terminalis (8, 3.0%), CS (10, 3.7%), and others (10, 3.7%). The incidence of PV foci in the left superior PV (LSPV) was significantly higher in patients with well-developed VOM than in those without (66% vs 42%, P < 0.05). Twenty-eight patients had 30 non-PV foci around the LSPV ostium. We successfully ablated the non-PV foci at the distal end of VOM in 11 patients. The ends of the VOM branches were good markers to search for non-PV foci. Seven of 11 (64%) patients with successful ablation of non-PV foci were free from arrhythmia, whereas only 6 of 17 (35%) were free from arrhythmia in those with residual non-PV foci.
Conclusions: To determine VOM anatomy is important to identify non-PV foci around the ends of VOM.     

Effect of pulmonary vein isolation on the left-to-right atrial dominant frequency gradient in human atrial fibrillation

BACKGROUND: We previously demonstrated the existence of a left-to-right atrial dominant frequency gradient during paroxysmal but not persistent atrial fibrillation (AF) in humans. One possible mechanism of the left-to-right dominant frequency gradient involves the role of the pulmonary veins (PVs) in AF maintenance. OBJECTIVES: The purpose of this study was to examine the effect of PV isolation on the dominant frequency gradient and outcome after PV isolation. METHODS: Patients with either paroxysmal or persistent AF were studied. Recordings were made from catheters in the coronary sinus (CS), posterior right atrium (RA), and posterior left atrium (LA) during AF before and after PV isolation. Mean left-to-right dominant frequency gradient was measured before and after segmental PV isolation. Patients were followed for AF recurrence after PV isolation. RESULTS: Twenty-seven patients with paroxysmal (n = 15) or persistent (n = 12) AF were studied. In the paroxysmal group, baseline dominant frequency was greatest in the posterior LA with a significant left-to-right atrial dominant frequency gradient (posterior LA = 6.2 +/- 0.9 Hz, CS = 5.8 +/- 0.8 Hz, posterior RA = 5.4 +/- 0.9 Hz; P <.001). After PV isolation, there was no regional difference in dominant frequency (5.9 +/- 0.7 Hz vs 5.7 +/- 0.6 Hz vs 5.7 +/- 0.7 Hz, respectively; P = NS). In the persistent AF group, there was no overall difference in dominant frequency among sites before or after PV isolation (P = NS); however, patients with long-term freedom from AF after PV isolation had a higher left-to-right dominant frequency gradient compared with patients with recurrent AF (0.4 vs 0.1 Hz; P <.05). CONCLUSION: PV isolation results in a loss in the left-to-right dominant frequency gradient in patients with paroxysmal AF. This finding supports the critical role of PVs in the maintenance of ongoing paroxysmal AF. Patients with persistent AF and a baseline left-to-right dominant frequency gradient have a better success rate with PV isolation alone compared with patients without a dominant frequency gradient.