BACKGROUNDThe end point for catheter ablation of pulmonary vein (PV) foci initiating atrial fibrillation (AF) has not been determined.METHODS AND RESULTSNinety patients underwent mapping during spontaneous or induced ectopy and/or AF initiation. Ostial PV ablation was performed by use of angiograms to precisely define targeted sites. Success defined by elimination of AF without drugs was correlated with the procedural end point of the abolition of distal PV potentials. A total of 197 arrhythmogenic PV foci (97%)-single in 31% and multiple in 69%-and 6 atrial foci were identified. A discrete radiofrequency (RF) application eliminated the PV potentials in 9 PV foci, whereas 2 foci from the same PV required RF applications at separate sites in 19 cases. In others, a wider region was targeted with progressive elimination of ectopy. In 49 patients, multiple sessions were necessary owing to recurrent or new ectopy. The clinical success rates were 93%, 73%, and 55% in patients with 1, 2, and > or =3 arrhythmogenic PV foci. Recovery of local PV potential and the inability to abolish it were significantly associated with AF recurrences (90% success rate with versus 55% without PV potential abolition). PV stenosis was noted acutely in 5 of 6 cases, remained unchanged at restudy, and was associated with RF power >45 W.CONCLUSIONSMultiple PV foci are involved in initiation of AF, and elimination of PV muscle conduction is associated with clinical success.

Introduction: We assessed the mode of reinitiation of atrial fibrillation (AF) after cardioversion and the efficacy of ablating these foci of reinitiation in patients with chronic AF.Methods and Results: Fifteen patients, 7 with structural heart disease, underwent mapping and catheter ablation of drug-resistant AF documented to be persistent for 5 +/- 4 months. In all patients, cardioversion was followed by documentation of P on T atrial ectopy and early recurrence, which allowed mapping of the reinitiating trigger or the source of ectopy. Radiofrequency (RF) ablation was performed at pulmonary vein (PV) ostia using a target temperature of 50 degrees C and a power limit of 30 to 40 W, with the endpoint being interruption of all local muscle conduction, A total of 32 arrhythmogenic PVs and 2 atrial foci (left septum and left appendage) were identified: 1, 2, and 3 or 4 PVs in 5, 3, and 6 patients. RF applications at the ostial perimeter resulted in progressively increasing delay, followed by abolition of PV potentials in 8, but potentials persisted in 6, A single ablation session was performed in 7 patients and 8 underwent two or three sessions because of recurrence of AF; ablation was directed at the same source due to recovery of local PV potential or at a different PV, No PV stenosis was noted either acutely or at repeated follow-up angiograms. Nine patients (60%) were in stable sinus rhythm without antiarrhythmic drugs at follow-up of 11 +/- 8 months. Anticoagulants were interrupted in 7 patients.Conclusion: PVs are the dominant triggers reinitiating chronic AF in this patient population. Elimination of PV potentials by ostial RF applications results in stable sinus rhythm in 60%. A larger group and longer follow-up are needed to investigate further the role of trigger ablation in curative therapy for chronic AF.

Biventricular (BV) pacing is a promising treatment of end‐stage heart failure. This article describes our experience with a strictly endocardial BV pacing system in patients with severe congestive heart failure. Three women and eight men (age 65 ± 9 years) with drug‐resistant end‐stage CHF underwent implantation of an endocardial BV pacing system. In the first seven patients, the left ventricular lead was placed via a combined femoral and internal jugular approach. In the last four patients, the transseptal puncture was directly performed via the right internal jugular vein with a dedicated kit. The procedure was successful in all 11 patients. The acute left ventricular and BV thresholds were 1.3 ± 0.6 V and 2.4 ± 1 V, respectively. The QRS duration decreased from 214 ± 57 to 176 ± 25 ms. A functional improvement was noted in ten patients with a decrease in mean NYHA functional class from 3.7 ± 0.5 before, to 2.6 ± 0.9 after system implantation. A significant decrease in pulmonary capillary wedge pressure and increase in cardiac output were measured in eight patients. During follow‐up, four patients died from CHF (n = 3) or ventricular fibrillation (n = 1). Under oral anticoagulation, no thromboembolic event was observed but one transient ischemic attack occurred in one patient whose anticoagulation was interrupted. Endocardial BV pacing is technically feasible and appears safe, though further studies are needed before it is used on a larger scale.

Background-Dual-loop atrial reentrant tachycardias have not been clinically described.Methods and Results-Five patients (3 men, 2 women; mean age, 48+/-16 years) were studied 24+/-15 years after surgical closure of an ostium secundum atrial septal defect for drug-resistant atrial tachycardia, Complete tachycardia mapping was per formed in the right atrium with multipolar catheters and a 3-dimensional electroanatomic mapping system (Biosense), followed by linear radiofrequency ablation of the narrowest part of each complete loop. Six tachycardias with a typical flutter morphology, a cycle length of 262+/-40 ms, and a superior f-wave axis (-77+/-11 degrees) were mapped, 4 with a Biosense map including 106+/-32 points. Five figure-8 tachycardias had a counterclockwise loop around the tricuspid valve sharing a common anterior channel with a clockwise loop around the lateral atriotomy scar. One tachycardia was thought to have 2 counterclockwise loops around the same obstacles. Radiofrequency delivery in the cavotricuspid isthmus in each case transformed the tachycardia without any pause in a different morphology tachycardia with an inferior P-wave axis (50+/-42 degrees) and nearly the same cycle length (272+/-39 ms) but with the periatriotomy loop alone. This arrhythmia required ablation of a second isthmus: between the lower end of the atriotomy and the inferior vena cava in 4 and the superior tricuspid annulus in 1. After a follow-up of 19+/-6 months, there were no recurrences.Conclusions-Figure-8 double-loop tachycardias mimicking the ECG pattern of a common atrial flutter occur in some patients after a surgical atriotomy, Ablation of 1 loop produces a sudden transformation to a new reentrant tachycardia formed of the remaining loop that requires ablation at a second isthmus.

Background-Typical right atrial isthmus-dependent flutters have been described in detail, but very little is known about left atrial (LA) flutters.Methods and Results-We performed conventional and 3D mapping of the LA for 22 patients with atypical flutters. Complete maps in 17 patients demonstrated macroreentrant circuits (n=15) with 1 to 3 loops rotating around the mitral annulus, the pulmonary veins, and a zone of block or a silent area. In 2 patients, a small reentry circuit with a zone of markedly slow conduction was identified. Linear ablation performed across the most accessible part of the circuit cured 16 patients (73%) with a follow-up of 15+/-7 months.Conclusions-LA reentrant tachycardias are related to individually varying circuits and are amenable to mapping guided radiofrequency ablation.

OBJECTIVES We sought to assess the dynamic temporal course of conduction recovery during and after radiofrequency (RF) catheter ablation of the cavotricuspid isthmus.BACKGROUND Although cavotricuspid isthmus block is accepted as the best end point of ablation for typical flutter, conduction recovery is thought to underlie many eventual recurrences. Its time course and frequency have not been determined.METHODS In a prospective group of 30 patients (26 men and 4 women, age 64 +/- 12 years) undergoing ablation of typical flutter in the cavotricuspid isthmus, the morphology of the P wave during pacing from the low lateral right atrium after achievement of complete isthmus block was identified as a reference. Regression of this morphologic P wave change was confirmed to be associated with intracardiac evidence of the recovery of cavotricuspid isthmus conduction and was observed throughout the procedure both during ablation in sinus rhythm (n = 15, group B) and just after flutter termination (n = 15, group A).RESULTS Stable complete isthmus block was achieved in all patients; 29 had a terminal positivity of the paced P wave. Flutter termination resulted in stable block and terminal P wave positivity in three patients, transient terminal P wave positivity and transient block despite continuing RF at the same site in five patients and no block in the remaining seven patients. Conduction recovery identified by recovery of P wave changes was nearly as common (48%) during ablation in sinus rhythm. Multiple recoveries were noted in some patients, and 72% of all recoveries occurred within 1 min.CONCLUSIONS Conduction recovery was only rarely associated with coagulum, impedance elevation or pops. Conduction recovery in the cavotricuspid isthmus is common during and after ablation and can be accurately, dynamically and continuously observed by monitoring the recovery of the low lateral right atrial paced P wave change. (C) 2000 by the American College of Cardiology.

RF catheter ablation is highly effective in eliminating atrioventricular nodal reentrant tachycardia by targeting the slow pathway in the posteroinferior part of Koch's triangle in the right atrium. We report here a patient in whom "slow-fast" atrioventricular nodal reentrant tachycardia was eliminated only by ablation of the slow path way in the left atrial posteroseptal region at the level of the mitral annulus after unsuccessful attempts at the traditional site on the right side.

Typical atrial flutter, as referred to in this article, includes both the counterclockwise and the clockwise form of cavotricuspid isthmus-dependent right atrial flutter. The counterclockwise form is the most common and characterized by a stereotypical surface ECG pattern showing negative sawtooth flutter waves in II, III and aVF at a rate between 200–350 beats.min. This surface ECG morphology of counterclockwise typical flutter is remarkably consistent, allowing assumptions about the circuit being entirely within the right atrium and obligatory activation through the cavotricuspid isthmus. However, in contrast, the surface ECG morphology of clockwise flutter is more variable and difficult to distinguish from non-isthmus-dependent flutters. As a result, intracardiac activation mapping and entrainment mapping is often necessary as confirmation. Importantly, since both the clockwise and the counterclockwise forms share the same obligatory cavotricuspid isthmus, a common strategy of ablation is clearly applicable and has been shown to be effective.

A patient with marked first-degree AV block and a DDDR pacemaker presented with a history of paroxysmal narrow QRS tachycardia, subsequently identified as sinus tachycardia (with a very long PR interval), causing a clinical problem similar to pacemaker syndrome because of loss of AV synchrony. The latter resulted from an excessively long postventricular atrial refractory period (PVARP) that prevented sensing of sinus P waves, The unfavorable hemodynamics caused reflex sinus tachycardia. The long PVARP was mandated by the mode switching algorithm of this particular device and was automatically set according to the selected tachycardia detection rate. The patient became asymptomatic when the mode switching function was turned off and the PVARP shortened.

We performed radiofrequency catheter ablation (RFCA) in 12 consecutive patients (17–77 years) with daily, symptomatic, monomorphic ventricular ectopy (VE) (12,096 ± 3.326 on 24‐hour Holter) resistant to antiarrhythmic drugs. Nine patients had no apparent structural heart disease, 1 patient had a mild dilated cardiomyopathy, 1 patient had a treated mitral stenosis, and 1 patient had arrhythmogenic ventricular dysplasia. VE morphology was LBBB with inferior axis in 9 patients, RBBB with inferior axis in 2 patients, RBBB with superior axis in 1 patient. None of the patients had spontaneous or inducible sustained ventricular tachycardia. The VE focus was targeted with RF energy at the earliest endocardial activation site and based on a matching 12‐lead ECG pace map. The VE focus was localized in the right outflow tract in 9 patients and on the left ventricle in 3 patients. RFCA was delivered with a standard 4‐mm tip electrode. The ablation was initially successful in 11 patients and unsuccessful in 1 patient. All successfully ablated patients were asymptomatic and discharged without antiarrhythmic drugs. During follow‐up (25 ± 8; 17–38 months), two patients had a recurrence of symptoms, which were controlled by a previously ineffective drug. At the end of follow‐up, 1,329 ± 3198 VE were observed on Holter monitoring (P < 0.001 compared with initial values). No short‐ and long‐term complications were observed. RFCA is a safe and effective method for treating drug‐resistant symptomatic monomorphic VE in carefully selected patients. A persistent benefit without complications was obtained over a 2‐year follow‐up.

BACKGROUNDCatheter ablation of typical right atrial flutter is now widely performed. The best end point has been demonstrated to be bidirectional isthmus block. We investigated the use of irrigated-tip catheters in a small subset of patients who failed isthmus ablation with conventional radiofrequency (RF) ablation.METHODS AND RESULTSOf 170 patients referred for ablation of common atrial flutter, conventional ablation of the cavotricuspid isthmus with >21 applications failed to create a bidirectional block in 13 (7.6%). An irrigated-tip catheter ablation was performed on identified gaps in the ablation line according to a protocol found to be safe in animals: a moderate flow rate of 17 mL/min and temperature-controlled (target, 50 degrees C) RF delivery with a power limit of 50 W. Bidirectional isthmus block was achieved in 12 patients by use of a mean delivered power of 40+/-6 W with a single application in 6 patients and 2 to 6 applications in the other 6. No side effects occurred during or after the procedure.CONCLUSIONSIrrigated-tip catheter ablation is safe and effective for achieving cavotricuspid isthmus block when conventional RF energy has failed.

Introduction: Some posteroseptal accessory pathways (APs) can be successfully ablated by radiofrequency current only from inside the coronary sinus (CS) or its branches, because of an absolute or relatively epicardial location, The aim of this study was to identify ECG features of manifest posteroseptal APs requiring ablation in the CS or the middle cardiac veins (MCVs),Methods and Results: One hundred seventeen consecutive patients with manifest posteroseptal APs successfully ablated: (1) greater than or equal to 1 cm deep inside the MCV (group MCV: n = 13); (2) inside the CS, including the area adjacent to the MCV ostium (group CS: n = 10); (3) at the right (group R: n = 60); or (4) the left posteroseptal endocardial region (group L: n = 34) were included. We reviewed delta wave polarity (initial 40 msec) and QRS morphology during sinus rhythm and atrial pacing as well as electrogram characteristics in these patients. The local target site electrogram in groups MCV and CS was characterized by a longer atrial to ventricular electrogram interval, suggesting a longer course of the pathway and more frequent recording of a presumptive AP potential compared to the group ablated at the right or left endocardium, The most sensitive ECG feature for group CS or group MCV was a negative delta wave in lead II in sinus rhythm (87%), but specificity (79%) and positive predictive value (50%) were relatively low. A steep positive delta wave in aVR during maximal preexcitation possessed the highest specificity and positive predictive value (98% and 88%, sensitivity 61%) which increased to 99% and 91%, respectively, when combined with a deep S wave in V-6 (R wave less than or equal to S wave).Conclusion: These data suggest that posteroseptal APs ablated inside the coronary venous system have highly specific features, including the combination of a steep positive delta wave in lead aVR and a deep S wave in lead V-6 (R wave I S wave) during maximal preexcitation, The highest sensitivity is provided by a negative delta wave in lead II. These findings may be helpful for anticipating and planning an epicardial ablation strategy.

Transcatheter radiofrequency (RF) ablation of atrial fibrillation or flutter requires the creation of linear lesions. However, conventional catheters are not predictably effective because of poor endocardial contact, and limited lesion size and penetration. The purpose of the study was to assess, in the right atrium, the efficacy and safety of a new catheter designed to create long myocardial tissue lesions using RF energy. The main characteristics of this 8 Fr deflectable RF ablation catheter were: (1) a perpendicularly contacting articulated bilimb electrodes ensuring stable and firm endocardial firm contact; and (2) an irrigated planar interface. Three different electrode prototypes were tested. Fourteen anesthetized sheep weighing 61 ± 7 kg underwent RF ablation in the right atrium using three incremental power levels (25 to 45, 50, 55 to 75 W) with the aim of creating fully transmural (FT) lesions, defined as continuous and complete epicardial and endocardial lesion imprints. The animals were euthanized 1 hour later for macroscopic and histologic examinations. Forty‐three of the 80 right atrial lesions created, in smooth as well as in trabeculated areas, were FT. The percentage of FT lesions increased with the applied power from 37% with 25–45 W, to 49% with 50 W, and up to 86% for 55–75 W. In all but two cases, histologic examination showed no discontinuity between FT lesions produced by both limbs resulting in 19 coalescent linear lesions with an average size of 25 × 6 × 4 mm (length × width × depth). In situ bipolar electrograms after ablation in the FT group showed split potentials and/or a marked decrease in amplitude from 2.85 ± 1.79 to 0.33 ± 0.14 mV (P = 0.001) accompanied by near complete disappearance of unipolar electrograms. There was no perforation due to RF ablation. In conclusion, continuous and FT lesions can be achieved in various areas of sheep atria, including the trabecular right atrium, with a perpendicularly contacting bilimb electrode catheter. It represents a promising tool for catheter ablation of atrial fibrillation and flutter.

Catheter ablation of paroxysmal atrial fibrillation using long linear lesions in the right atrium is still under investigation, and its long‐term follow‐up is unknown. Methods: Thirty‐six men and nine women (aged 51 ± 12 years) with symptomatic daily episodes of AF for 6 ± 5 years despite the use of 4.7 ± 1.5 antiarrhythmic drugs were studied between July 1994 and January 1996. Progressively longer ablation lines were performed in 3 groups of 15 consecutive patients each, using a 14‐electrode catheter or a single‐electrode dragging technique. Success was defined as atrial fibrillation elimination or recurrence for no longer than 6 hours over 3 months of observation. Patients who had fewer than 6 hours of atrial fibrillation per month were considered “improved.” Medium‐ (11 ± 4 months) and long‐term (26 ± 5 months) results were assessed clinically from a patient's diary and from Holter recordings. Results: After a follow‐up of 11 months, 24 patients had a favorable result of the ablation procedure with or without additional antiarrhythmic drug therapy, representing 53% of the original cohort. After 26 ± 5 months of follow‐up, these successful results were reduced to 17 patients (37%). Conclusions: After linear atrial ablation, a significant long‐term attrition of arrhythmia‐free patients was observed. This may be due to a combination of disease progression, incomplete linear block, and ineffective ablation of arrhythmogenic triggers.

Atrioventricuiar junctional reentrant tachycardia (AVfBT) is the most common form of paroxysmal regular supraventricular tachycardia. In patients with disabling, drug refractory AVJBT, catheter ablation has evolved rapidly from a last‐resort treatment in the form of interruption of atrioventricular (AV) conduction to selective modification of AV nodal function as an ideal treatment. This article will focus on the frequently unappreciated electrophysiological activities recordable in man in Kach's triangle during ablation of the so‐called slow pathway.

Background Despite verification of bidirectional conduction block after radiofrequency (RF) catheter ablation in the inferior vena cava (IVC)-tricuspid annulus (TA) isthmus, recurrence of common atrial flutter is relatively common. Although complete linear reablation is usually performed, we evaluated a simplified electrophysiological strategy selectively targeting recovered conducting isthmus tissue.Methods and Results Twenty-one patients (18 men and 3 women, age, 54+/-10 years) with a recurrence of typical atrial flutter 6+/-7 months after an apparently successful catheter ablation in the IVC-TA isthmus prospectively underwent electrophysiologically targeted reablation during flutter. Sites with narrow electrograms or fractionated electrograms interposed between adjacent sites with double potentials considered to represent gaps were ablated without movement of the catheter. Mapping showed that 18 of 21 patients had a single gap. Successful ablation required a single application in 14 patients and, in the group as a whole, a median of one application (mean, 2+/-2; range, 1 to 11) with resultant bidirectional block in 13 of 16. A single narrow electrogram (duration, 48+/-6 ms; amplitude, 0.1+/-0.05 mV) was noted at the successful site in 11, whereas a fractionated electrogram (97+/-32 ms, 0.05+/-0.04 mV, P<.05) was noted in 9. There were four additional recurrences during a follow-up at 7+/-5 months; three were similarly ablated with a median of one pulse.Conclusions Transmural ablation lesions in the isthmus can be recognized during flutter by double potentials separated by an isoelectric interval. Postablation recurrent flutter is usually due to a single discrete recovered gap; this is represented by a single or a fractionated potential spanning the isoelectric interval of adjacent double potentials, which can be selectively targeted to minimize repeat ablation.