Pectus excavatum: uncommon electrical abnormalities caused by extrinsic right ventricular compression.

We report a case of pectus excavatum associated with ventricular tachycardia provoked by exercise in a 19-year-old man. Although this chest deformity has been associated with supraventricular dysrhythmias, documented ventricular tachycardia has only been reported once. Our patient's ventricular dysrhythmia was treated by surgical correction of his pectus excavatum only, and at 3 years follow-up he has had no recurrence of his ventricular tachycardia.

Catheter ablation of ventricular fibrillation triggers and electrical storm.

Ventricular fibrillation (VF) and electrical storm remain challenging conditions to manage despite the availability of various treatment modalities. Insertion of an implantable cardioverter defibrillator (ICD) remains the gold standard method for lowering the risk of sudden cardiac death in patients deemed to be at greatest risk of ventricular arrhythmias. However, ICDs do not alter the underlying substrate responsible for the arrhythmic events and a significant proportion of patients with ICDs may experience VF storm which may be life threatening and difficult to control with medication. Catheter ablation (CA) of the triggers or abnormal electrical substrate responsible for VF storm is an important treatment option in rare cases. In this article, we present an overview of the current theories underlying the mechanisms of VF and discuss how the technique of CA may be used to treat the triggers of VF and electrical storm. We review the literature on outcomes in patients who have undergone CA for VF in a variety of different settings, including those with structural heart disease and structurally normal hearts (e.g. patients with inherited arrhythmogenic diseases and idiopathic VF) and discuss the future directions in this field.

Loss-of-function mutations in the cardiac calcium channel underlie a new clinical entity characterized by ST-segment elevation, short QT intervals, and sudden cardiac death.

BACKGROUND: Cardiac ion channelopathies are responsible for an ever-increasing number and diversity of familial cardiac arrhythmia syndromes. We describe a new clinical entity that consists of an ST-segment elevation in the right precordial ECG leads, a shorter-than-normal QT interval, and a history of sudden cardiac death. METHODS AND RESULTS: Eighty-two consecutive probands with Brugada syndrome were screened for ion channel gene mutations with direct sequencing. Site-directed mutagenesis was performed, and CHO-K1 cells were cotransfected with cDNAs encoding wild-type or mutant CACNB2b (Ca(v beta2b)), CACNA2D1 (Ca(v alpha2delta1)), and CACNA1C tagged with enhanced yellow fluorescent protein (Ca(v)1.2). Whole-cell patch-clamp studies were performed after 48 to 72 hours. Three probands displaying ST-segment elevation and corrected QT intervals < or = 360 ms had mutations in genes encoding the cardiac L-type calcium channel. Corrected QT ranged from 330 to 370 ms among probands and clinically affected family members. Rate adaptation of QT interval was reduced. Quinidine normalized the QT interval and prevented stimulation-induced ventricular tachycardia. Genetic and heterologous expression studies revealed loss-of-function missense mutations in CACNA1C (A39V and G490R) and CACNB2 (S481L) encoding the alpha1- and beta2b-subunits of the L-type calcium channel. Confocal microscopy revealed a defect in trafficking of A39V Ca(v)1.2 channels but normal trafficking of channels containing G490R Ca(v)1.2 or S481L Ca(v beta2b)-subunits. CONCLUSIONS: This is the first report of loss-of-function mutations in genes encoding the cardiac L-type calcium channel to be associated with a familial sudden cardiac death syndrome in which a Brugada syndrome phenotype is combined with shorter-than-normal QT intervals.

Implantation of lumenless pacing leads at the inter-atrial septum and right ventricular outflow tract with deflectable catheter-sheath.

Current permanent right ventricular and right atrial endocardial pacing leads are implanted utilizing a central lumen stylet. Right ventricular apex pacing initiates an abnormal asynchronous electrical activation pattern, which results in asynchronous ventricular contraction and relaxation. When pacing from right atrial appendage, the conduction time between two atria will be prolonged, which results in heterogeneity for both depolarization and repolarization. Six patients with Class I indication for permanent pacing were implanted with either single chamber or dual chamber pacemaker. The SelectSecure 3830 4-French (Fr) lumenless lead and the SelectSite C304 8.5-Fr steerable catheter-sheath (Medtronic Inc., USA) were used. Pre-selected pacing sites included inter-atrial septum and right ventricular outflow tract, which were defined by ECG and fluoroscopic criteria. All the implanting procedures were successful without complication. Testing results (mean atrial pacing threshold: 0.87 V; mean P wave amplitude: 2.28 mV; mean ventricular pacing threshold: 0.53V; mean R wave amplitude: 8.75 mV) were satisfactory. It is concluded that implantation of a 4-Fr lumenless pacing lead by using a streerable catheter-sheath to achieve inter-atrial septum or right ventricular outflow tract pacing is safe and feasible.

Localized sources maintaining atrial fibrillation organized by prior ablation.

BACKGROUND: Endocardial mapping of localized sources driving atrial fibrillation (AF) in humans has not been reported. METHODS AND RESULTS: Fifty patients with AF organized by prior pulmonary vein and linear ablation were studied. AF was considered organized if mapping during AF showed irregular but discrete atrial complexes exhibiting consistent activation sequences for >75% of the time using a 20-pole catheter with 5 radiating spines covering 3.5-cm diameter or sequential conventional mapping. A site or region centrifugally activating the remaining atrial tissue defined a source. During AF with a cycle length of 211+/-32 ms, activation mapping identified 1 to 3 sources at the origin of atrial wavefronts in 38 patients (76%) predominantly in the left atrium, including the coronary sinus region. Electrograms at the earliest area varied from discrete centrifugal activation to an activity spanning 75% to 100% of the cycle length in 42% of cases, the latter indicating complex local conduction or a reentrant circuit. A gradient of cycle length (>20 ms) to the surrounding atrium was observed in 28%. Local radiofrequency ablation prolonged AF cycle length by 28+/-22 ms and either terminated AF or changed activation sequence to another organized rhythm. In 4 patients, the driving source was isolated, surrounded by the atrium in sinus rhythm, and still firing at high frequency (228+/-31 ms) either permanently or in bursts. CONCLUSIONS: AF associated with consistent atrial activation sequences after prior ablation emanates mostly from localized sources that can be mapped and ablated. Some sources harbor electrograms suggesting the presence of localized reentry.

Catheter ablation for atrial fibrillation in congestive heart failure.

BACKGROUND: Congestive heart failure and atrial fibrillation often coexist, and each adversely affects the other with respect to management and prognosis. We prospectively evaluated the effect of catheter ablation for atrial fibrillation on left ventricular function in patients with heart failure. METHODS: We studied 58 consecutive patients with congestive heart failure and a left ventricular ejection fraction of less than 45 percent who were undergoing catheter ablation for atrial fibrillation. We selected as controls 58 patients without congestive heart failure who were undergoing ablation for atrial fibrillation, matched according to age, sex, and classification of atrial fibrillation. We evaluated the patients' left ventricular function and dimensions, symptom score, exercise capacity, and quality of life at baseline and at months 1, 3, 6, and 12. RESULTS: After a mean (+/-SD) of 12+/-7 months, 78 percent of the patients with congestive heart failure and 84 percent of the controls remained in sinus rhythm (P=0.34) (69 percent and 71 percent, respectively, were in sinus rhythm without the administration of antiarrhythmic drugs). The patients with congestive heart failure had significant improvement in left ventricular function (increases in the ejection fraction and fractional shortening of 21+/-13 percent and 11+/-7 percent, respectively; P<0.001 for both comparisons), left ventricular dimensions (decreases in the diastolic and systolic diameters of 6+/-6 mm and 8+/-7 mm, respectively; P=0.03 and P<0.001, respectively), exercise capacity, symptoms, and quality of life. The ejection fraction improved significantly not only in patients without concurrent structural heart disease (24+/-10 percent, P<0.001) and those with inadequate rate control before ablation (23+/-10 percent, P<0.001), but also in those with coexisting heart disease (16+/-14 percent, P<0.001) and adequate rate control before ablation (17+/-15 percent, P<0.001). CONCLUSIONS: Restoration and maintenance of sinus rhythm by catheter ablation without the use of drugs in patients with congestive heart failure and atrial fibrillation significantly improve cardiac function, symptoms, exercise capacity, and quality of life.

Techniques, evaluation, and consequences of linear block at the left atrial roof in paroxysmal atrial fibrillation: a prospective randomized study.

BACKGROUND: There are no reports describing the technique, electrophysiological evaluation, and clinical consequences of complete linear block at roofline joining the superior pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: Ninety patients with drug-refractory paroxysmal AF undergoing radiofrequency ablation were prospectively randomized into 2 ablation strategies: (1) PV isolation (n=45) or (2) PV isolation in combination with linear ablation joining the 2 superior PVs (roofline; n=45). In both groups, the cavotricuspid isthmus, fragmented peri-PV-ostial electrograms, and spontaneous non-PV foci were ablated. Roofline ablation was performed at the most cranial part of the left atrium (LA) with complete conduction block demonstrated during LA appendage pacing by the online mapping of continuous double potential and an activation detour propagating around the PVs to activate caudocranially the posterior wall of the LA. The effect of ablation at the LA roof was evaluated by the change in fibrillatory cycle length, termination and noninducibility of AF, and clinical outcome. PV isolation was achieved in all patients with no significant differences in the radiofrequency duration, fluoroscopy, or procedural time between the groups. Roofline ablation required 12+/-6 (median 11, range 3 to 25) minutes of radiofrequency energy delivery with a fluoroscopic duration of 7+/-2 minutes and was performed in 19+/-7 minutes. Complete block was confirmed in 43 patients (96%) and resulted in an activation delay that was shorter circumventing the left than the right PVs during LA appendage pacing (138+/-15 versus 146+/-25 ms, respectively; P=0.01). Roofline ablation resulted in a significant increase in the fibrillatory cycle length (198+/-38 to 217+/-44 ms; P=0.0005), termination of arrhythmia in 47% (8/17), and subsequent noninducibility of AF in 59% (10/17) of the patients inducible after PV isolation. However, LA flutter, predominantly perimitral, could be induced in 10 patients (22%) after roofline ablation. At 15+/-4 months, 87% of the roofline group and 69% with PV isolation alone are arrhythmia free without antiarrhythmics (P=0.04). CONCLUSIONS: This prospective randomized study demonstrates the feasibility of achieving complete linear block at the LA roof. Such ablation resulted in the prolongation of the fibrillatory cycle, termination of AF, and subsequent noninducibility and is associated with an improved clinical outcome compared with PV isolation alone.

Spectral analysis identifies sites of high-frequency activity maintaining atrial fibrillation in humans.

BACKGROUND: The identification of sites of dominant activation frequency during atrial fibrillation (AF) in humans and the effect of ablation at these sites have not been reported. METHODS AND RESULTS: Thirty-two patients undergoing AF ablation (19 paroxysmal, 13 permanent) during ongoing arrhythmia were studied. Electroanatomic mapping was performed, acquiring 126+/-13 points per patient throughout both atria and coronary sinus. At each point, 5-second electrograms were obtained to determine the highest-amplitude frequency on spectral analysis and to construct 3D dominant frequency (DF) maps. The temporal stability of the recording interval was confirmed in a subset. Ablation was performed with the operator blinded to the DF maps. The effect of ablation at sites with or without high-frequency DF sites (maximal frequencies surrounded by a decreasing frequency gradient > or =20%) was evaluated by determining the change in AF cycle length (AFCL) and the termination and inducibility of AF. The spatial distribution of the DF sites was different in patients with paroxysmal and permanent AF; paroxysmal AF patients were more likely to harbor the DF site within the pulmonary vein, whereas in permanent AF, atrial DF sites were more prevalent. Ablation at a DF site resulted in significant prolongation of the AFCL (180+/-30 to 198+/-40 ms; P<0.0001; kappa=0.77), whereas in the absence of a DF site, there was no change in AFCL (169+/-22 to 170+/-22 ms; P=0.4). AF terminated during ablation in 17 of 19 patients with paroxysmal and 0 of 13 with permanent AF (P<0.0001). When 2 patients with nonsustained AF during mapping were excluded, 13 of 15 (87%) had AF termination at DF sites (54% at the initially ablated DF site): 11 pulmonary veins and 2 atrial. In addition, AF could no longer be induced in 69% with termination of AF at a DF site. There were no significant differences in the number or percentage of DF sites detected (5.4+/-1.6 versus 4.9+/-2.1; P=0.3) and ablated (1.9+/-1.0 versus 2.4+/-1.0; P=0.3) in those with and without AF termination. The duration of radiofrequency ablation to achieve termination was significantly shorter than that delivered in those with persisting AF (34.8+/-24.0 versus 73.5+/-22.9 minutes; P=0.0002). All patients with persisting AF had additional DF sites outside the ablated zones. CONCLUSIONS: Spectral analysis and frequency mapping identify localized sites of high-frequency activity during AF in humans with different distributions in paroxysmal and permanent AF. Ablation at these sites results in prolongation of the AFCL and termination of paroxysmal AF, indicating their role in the maintenance of AF.

Characterization of conduction recovery across left atrial linear lesions in patients with paroxysmal and persistent atrial fibrillation.

BACKGROUND: Left atrial (LA) linear lesions are effective in substrate modification for atrial fibrillation (AF). However, achievement of complete conduction block remains challenging and conduction recovery is commonly observed. The aim of the study was to investigate the localization of gap sites of recovered LA linear lesions. METHODS AND RESULTS: Forty-eight patients with paroxysmal (n = 26) and persistent/permanent (n = 22) AF underwent repeat ablation after pulmonary vein (PV) isolation and LA linear ablation at the LA roof and/or mitral isthmus due to recurrences of AF or flutter. In 35 patients, conduction through the mitral isthmus line (ML) had recovered whereas roof-line recovery was observed in 30 patients. The gaps within the ML were distributed to the junction between left inferior PV and left atrial appendage in 66%, the middle part of the ML in 20%, and in 8% to the endocardial aspect of the ML while only 6% of lines showed an epicardial site of recovery. The RL predominantly recovered close to the right superior PV (54%) and less frequently in the mid roof or close to the left PV (both 23%). Reablation of lines required significantly shorter RF durations (ML: 7.24 +/- 5.55 minutes vs 24.08 +/- 9.38 minutes, RL: 4.24 +/- 2.34 minutes vs 11.54 +/- 6.49 minutes; P = 0.0001). Patients with persistent/permanent AF demonstrated a significantly longer conduction delay circumventing the complete lines than patients with paroxysmal AF (228 +/- 77 ms vs 164 +/- 36 ms, P = 0.001). CONCLUSIONS: Gaps in recovered LA lines were predominantly located close to the PVs where catheter stability is often difficult to achieve. Shorter RF durations are required for reablation of recovered linear lesions. Conduction times around complete LA lines are significantly longer in patients with persistent/permanent AF as compared to patients with paroxysmal AF.

Frequency mapping of the pulmonary veins in paroxysmal versus permanent atrial fibrillation.

INTRODUCTION: The pulmonary veins (PVs) are a dominant source of triggers initiating atrial fibrillation (AF). While recent evidence implicates these structures in the maintenance of paroxysmal AF, their role in permanent AF is not known. The current study aims to compare the contribution of PV activity to the maintenance of paroxysmal and permanent AF. METHODS AND RESULTS: Thirty-four patients with paroxysmal AF (n = 20) or permanent AF (n = 14) undergoing ablation were studied. Prior to ablation, 32 seconds of electrograms were acquired from each PV and the coronary sinus (CS). The frequency of activity of each PV and CS was defined as the highest amplitude frequency on spectral analysis. The effects of ablation on the AF cycle length (AFCL) and frequency and on AF termination were determined. Significant differences were observed between paroxysmal and permanent AF. Paroxysmal AF demonstrates higher frequency PV activity (11.0 +/- 3.1 vs 8.8 +/- 3.0 Hz; P = 0.0003) but lower CS frequency (5.8 +/- 1.2 vs 6.9 +/- 1.4 Hz; P = 0.01) and longer AFCL (182 +/- 17 vs 158 +/- 21 msec; P = 0.002), resulting in greater PV to atrial frequency gradient (7.2 +/- 2.2 vs 4.2 +/- 2.9 Hz; P = 0.006). PV isolation in paroxysmal AF resulted in a greater decrease in atrial frequency (1.0 +/- 0.7 vs -0.05 +/- 0.4 Hz; P < 0.0001), greater prolongation of the AFCL (49 +/- 35 vs 5 +/- 6 msec; P < 0.0001), and more frequent AF termination (11/20 vs 0/14; P = 0.0007) compared to permanent AF. CONCLUSION: Paroxysmal AF is associated with higher frequency PV activity and lesser CS frequency compared to permanent AF. Isolation of the PVs had a greater impact on the fibrillatory process in paroxysmal AF compared to permanent AF, suggesting that while the PVs have a role in maintaining paroxysmal AF, these structures independently contribute less to the maintenance of permanent AF.

High-density activation mapping of fractionated electrograms in the atria of patients with paroxysmal atrial fibrillation.

BACKGROUND: Areas of complex fractionated atrial electrograms (CFAEs) have been implicated in the atrial substrate of atrial fibrillation (AF). The mechanisms underlying CFAE in humans are not well investigated. OBJECTIVES: The purpose of this study was to investigate the regional activation pattern associated with CFAE using a high-density contact mapping catheter. METHODS: Twenty patients with paroxysmal AF were mapped using a high-density multielectrode catheter. CFAE were mapped at 10 different sites (left atrium [LA]: inferior, posterior, roof, septum, anterior, lateral; right atrium [RA]: anterior, lateral, posterior, septum). Local atrial fibrillation cycle length (AFCL) was measured immediately before and after the occurrence of CFAE, and the longest electrogram duration (CFAEmax) was assessed. RESULTS: Longer electrogram durations were recorded in the LA compared with the RA (CFAEmax 118 +/- 21 ms vs 104 +/- 23 ms, P = .001). AFCL significantly shortened before the occurrence of CFAEmax compared with baseline (LA: 174 +/- 32 ms vs 186 +/- 32 ms, P = .0001; RA: 177 +/- 31 ms vs 188 +/- 31 ms, P = .0001) and returned to baseline afterwards. AFCL shortened by >or=10 ms in 91% of mapped sites. Two different local activation patterns were associated with occurrence of CFAEmax: a nearly simultaneous activation in all spines in 84% indicating passive activation, and a nonsimultaneous activation sequence suggesting local complex activation or reentry. CONCLUSION: Fractionated atrial electrograms during AF demonstrate dynamic changes that are dependent on regional AFCL. Shortening of AFCL precedes the development of CFAE; thus, cycle length is a major determinant of fractionation during AF. High-density mapping in AF may help to differentiate passive activation of CFAE from CFAE associated with an active component of the AF process.

Long-term evaluation of atrial fibrillation ablation guided by noninducibility.

BACKGROUND: Pulmonary vein (PV) isolation and linear lesions are effective in eliminating paroxysmal atrial fibrillation (AF), but linear lesions probably are not required in all patients. Noninducibility of AF has been shown to be associated with freedom from arrhythmia in 87% of patients. OBJECTIVES: The purpose of this study was to prospectively evaluate the role of noninducibility in guiding a stepwise approach tailored to the patient. METHODS: In 74 patients (age 53 +/- 8 years) with paroxysmal AF, PV isolation was performed during induced or spontaneous AF. If AF was inducible after PV isolation, one to two additional linear lesions were placed at the mitral isthmus and/or left atrial roof, with the endpoint of noninducibility of AF or atrial flutter. Inducibility (AF/atrial flutter, lasting > or = 10 minutes) was assessed using burst pacing at an output of 20 mA down to refractoriness from the coronary sinus and both atrial appendages. RESULTS: In 42 patients (57%), PV isolation restored sinus rhythm and rendered AF noninducible. In the 32 patients with persistent or inducible AF after PV isolation, a single linear lesion achieved noninducibility in 20, whereas two linear lesions were required in 12 and resulted in conversion to sinus rhythm and noninducibility in 10. Using this stepwise approach, a total of 69 patients (93%) were rendered noninducible. During follow-up of 18 +/- 4 months, 67 patients (91%) were free from arrhythmia without antiarrhythmic drugs. Repeat procedures were performed in 23 patients: repeat ablation was required to consolidate prior targets in 15 patients (20%), and "new" linear lesions, which were not predicted by inducibility during the index procedure, were required in 8 (11%). CONCLUSION: Noninducibility can be used as an endpoint for determining the subset of patients with paroxysmal AF who require additional linear lesions after PV isolation. This tailored approach is effective in 91% of patients while preventing delivery of unnecessary linear lesions.

Atrial fibrillation originating from persistent left superior vena cava.

BACKGROUND: The left superior vena cava (LSVC) is the embryological precursor of the ligament of Marshall, which has been implicated in the initiation and maintenance of atrial fibrillation (AF). Rarely, the LSVC may persist and has been associated with some organized arrhythmias, though not with AF. We report 5 patients in whom the LSVC was a source of ectopy, initiating AF. METHODS AND RESULTS: In 5 patients (4 men; age, 46+/-11 years) with symptomatic drug-refractory AF, ectopy from the LSVC resulting in AF was observed after pulmonary vein isolation. The ectopics were spontaneous in 2 and induced by isoproterenol in the others and preceded P-wave onset by 67+/-13 ms. During multielectrode or electroanatomic mapping, venous potentials were recorded circumferentially at the proximal LSVC near its junction with the coronary sinus (CS), but at the mid-LSVC level, they were recorded only on part of the circumference. The LSVC was electrically connected to the lateral left atrium (LA) and through the CS to the right atrium, with 4.1+/-2.3 CS-LSVC and 1.6+/-0.5 LA-LSVC connections per patient. Catheter ablation in the LSVC targeting these connections resulted in electrical isolation in 4 of the 5 patients without complications. After 15+/-10 months, the 4 patients with successful isolation, including 1 who had successful reablation for LA flutter, remained in sinus rhythm without drugs. CONCLUSIONS: The LSVC can be the arrhythmogenic source of AF with connections to the CS and LA. Ablation of these connections resulted in electrical isolation.

Changes in atrial fibrillation cycle length and inducibility during catheter ablation and their relation to outcome.

BACKGROUND: The modification of atrial fibrillation cycle length (AFCL) during catheter ablation in humans has not been evaluated. METHODS AND RESULTS: Seventy patients undergoing ablation of prolonged episodes of AF were randomized to pulmonary vein (PV) isolation or additional ablation of the mitral isthmus. Mean AFCL was determined at a distance from the ablated area (coronary sinus) at the following intervals: before ablation, after 2- and 4-PV isolations, and after linear ablation. Inducibility of sustained AF (> or =10 minutes) was determined before and after ablation. Spontaneous sustained AF (715+/-845 minutes) was present in 30 patients and induced in 26 (AFCL, 186+/-19 ms). PV isolation terminated AF in 75%, with the number of PVs requiring isolation before termination increasing with AF duration (P=0.018). PV isolation resulted in progressive or abrupt AFCL prolongation to various extents, depending on the PV: to 214+/-24 ms (P<0.0001) when AF terminated and to 194+/-19 ms (P=0.002) when AF persisted. The increase in AFCL (30+/-17 versus 14+/-11 ms; P=0.005) and the decrease in fragmentation (30.0+/-26.8% to 10.3+/-14.5%; P<0.0001) were significantly greater in patients with AF termination. Linear ablation prolonged AFCL, with a greater prolongation in patients with AF termination (44+/-13 versus 22+/-23 ms; P=0.08). Sustained AF was noninducible in 57% after PV isolation and in 77% after linear ablation. At 7+/-3 months, 74% with PV isolation and 83% with linear ablation were arrhythmia free without antiarrhythmics, which was significantly associated with noninducibility (P=0.03) with a recurrence rate of 38% and 13% in patients with and without inducibility, respectively. CONCLUSIONS: AF ablation results in a decline in AF frequency, with a magnitude correlating with termination of AF and prevention of inducibility that is predictive of subsequent clinical outcome.

Technique and results of linear ablation at the mitral isthmus.

BACKGROUND: This prospective clinical study evaluates the feasibility and efficacy of combined linear mitral isthmus ablation and pulmonary vein (PV) isolation in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: One hundred consecutive patients (13 women; age 55+/-10 years) with drug-refractory, symptomatic paroxysmal AF underwent PV isolation and linear ablation of the cavotricuspid isthmus and the mitral isthmus (lateral mitral annulus to the left inferior PV). They were compared with 100 consecutive patients (14 women; age, 52+/-10 years) undergoing PV isolation and cavotricuspid ablation without mitral isthmus ablation. Bidirectional mitral isthmus block was confirmed by demonstrating (1) a parallel corridor of double potentials during coronary sinus (CS) pacing, (2) an activation detour by pacing either side of the line, and (3) differential pacing techniques. Isolation of all PVs and cavotricuspid isthmus ablation were performed successfully in all. Mitral isthmus block was achieved in 92 patients after 20+/-10 minutes of endocardial radiofrequency application and an additional 5+/-4 minutes of epicardial radiofrequency application from within the CS in 68, resulting in a conduction delay of 151+/-26 ms during CS pacing. Thirty-two patients with mitral isthmus ablation compared with 49 without had recurrent atrial arrhythmia (P=0.02) requiring further ablation. At 1 year after the last procedure, 87 patients with mitral isthmus ablation and 69 without (P=0.002) were arrhythmia free without antiarrhythmic drugs, mitral isthmus ablation being the only factor associated with long-term success (RR for AF recurrence, 0.2; CI, 0.1 to 0.4; P<0.001). CONCLUSIONS: Catheter ablation of the mitral isthmus results consistently in demonstrable conduction block and is associated with a high cure rate for paroxysmal AF.

Reverse remodeling of sinus node function after catheter ablation of atrial fibrillation in patients with prolonged sinus pauses.

BACKGROUND: Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF. METHODS AND RESULTS: Twenty patients with paroxysmal AF and prolonged sinus pauses (> or =3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0+/-11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate (P=0.001), maximal heart rate (P<0.0001), and heart rate range (P<0.0001). The corrected sinus node recovery time decreased in all patients evaluated at 600 ms (P=0.016) and 400 ms (P=0.019). At 26.0+/-17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation. CONCLUSIONS: Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.

Mapping and ablation of ventricular fibrillation associated with long-QT and Brugada syndromes.

BACKGROUND: The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. METHODS AND RESULTS: Seven patients (4 men; age, 38+/-7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12+/-6 minutes of radiofrequency applications. During a follow-up of 17+/-17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. CONCLUSIONS: Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.

Effect of catheter ablation on quality of life of patients with paroxysmal atrial fibrillation.

BACKGROUND: Although improved quality of life is one of the primary aims of catheter ablation for paroxysmal atrial fibrillation, there is a paucity of published data on this topic. OBJECTIVES: The purpose of this study was to determine the effect of curative catheter ablation on the quality of life of patients with symptomatic, drug-refractory paroxysmal atrial fibrillation. METHODS: This was a prospective nonrandomized study of 63 consecutively enrolled patients (49 men and 14 women, age 56 +/- 7 years). Patients were excluded from the study if they had significant structural heart disease. The ablation strategy consisted of systematic isolation of all pulmonary veins, followed by limited linear ablation in the atria comprising left isthmus ablation (between the left inferior pulmonary vein and lateral mitral annulus) and cavotricuspid isthmus ablation. Patients completed quality-of-life questionnaires comprising the SF-36 and Symptom Checklist at baseline and 3 and 12 months following ablation. RESULTS: Fifty-four patients (86%) were free of symptomatic recurrence at 12-month follow-up. Successful ablation resulted in a significant improvement of all eight subscales of the SF-36 and of symptom frequency and severity scores of the symptom checklist at 3 months. This improvement was maintained at 12 months. CONCLUSIONS: Combined pulmonary vein isolation and linear atrial ablation has a high success rate for cure of paroxysmal atrial fibrillation. Successful curative catheter ablation of paroxysmal atrial fibrillation significantly and persistently improved quality of life during long-term follow-up. This improvement in quality of life was accompanied by a significant reduction in arrhythmia symptom frequency and severity.