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Introduction: Atrial fibrillation and atrial flutter often coexist. The long-term occurrence of atrial fibrillation in patients presenting with atrial flutter alone is unknown. We report the long-term follow-up in patients who underwent cavotricuspid isthmus ablation for treatment of lone atrial flutter., Methods and Results: Between January 1997 and June 2002, 632 patients underwent cavotricuspid isthmus ablation for the treatment of typical atrial flutter at the Cleveland Clinic Foundation. Three hundred sixty-three patients were included in this study and followed for a mean duration of 39 +/- 11 months. The mean duration of atrial flutter symptoms was 12 +/- 5 months. Mean left-atrial size and left-ventricular ejection fraction were 4.2 +/- 0.8 cm and 47 +/- 13%, respectively. After a mean follow-up time of 39 +/- 11 months, 13% (48 of 363) of the patients remained in sinus rhythm. Five percent (18 of 363) of patients experienced recurrence of atrial flutter only. Sixty-eight percent (246 of 363) experienced the onset of atrial fibrillation and 14% (51 of 363) experienced recurrence of atrial flutter and the new onset of atrial fibrillation. Overall, 82% (297 of 363) of the patients experienced new onset of drug refractory atrial fibrillation. Left-atrial size was a predictor of atrial fibrillation recurrence post-atrial flutter ablation., Conclusion: At long-term follow-up, approximately 82% of patients post-cavotricuspid isthmus ablation for atrial flutter developed drug refractory atrial fibrillation. This finding suggests that elimination of atrial flutter might delay, but does not prevent, atrial fibrillation. Evidence suggests both arrhythmias may share common triggers and such patients may derive a better long-term benefit from anatomical ablative treatment of atrial fibrillation as well.

Introduction: Phrenic nerve injury (PNI) is a complication that can occur with catheter ablation., Methods: Data from 17 patients with PNI following different catheter ablation techniques were reviewed. PNI was defined as decreased motility (transient) or paralysis (persistent) of the hemi-diaphragm on fluoroscopy or chest X-ray. Patient's recovery was monitored. Normalization of chest images and sniff test would be considered as complete clinical recovery., Results: Out of the 17 PNI patients (16 right, 1 left), 13 (11 persistent, 2 transient) occurred after pulmonary veins isolation with or without superior vena cava ablation. Three patients had persistent PNI after sinus node modification and one other patient experienced PNI after epicardial ventricular tachycardia ablation. Ablation was performed with different energy source including radiofrequency (n = 13), cryothermal (n = 1), ultrasound (n = 2) and laser (n = 1). Patient's symptoms varied broadly from asymptomatic to dyspnea, and even to respiratory insufficiency that required temporary mechanical ventilation support. Two patients with transient PNI resolved immediately after the procedure and the other 15 persistent PNI patients resolved within a mean time of 8.3 +/- 6.6 months., Conclusions: PNI caused by catheter ablation appears to functionally recover over time regardless of the energy sources used for the procedure.

Background: The incidence of atrial fibrillation (AF) in heart transplant patients has not been well documented., Methods: To determine the incidence of AF in a cohort of patients undergoing cardiac transplantation, clinical data were obtained from a prospectively collected database for all consecutive orthotopic heart transplantation (OHT) patients and for all consecutive coronary artery bypass graft (CABG) surgery patients between January 1984 and March 2004 at our institution. A cohort of 1,714 OHT patients and low-risk CABG (normal ejection fraction [EF] and no left ventricular hypertrophy [LVH]) patients were age- and sex-matched., Results: The average age in the two groups was 56 +/- 7 years with 87% male and 81% white race and body mass index (BMI) of 26 +/- 4. There were 3 cases of AF (0.3%) in the OHT group and 757 cases of AF (21%) in the low-risk CABG group. The strongest independent predictor of freedom from postoperative AF was having had a transplant (odds ratio [OR] 96, 95% confidence interval [CI] 13-720). The incidence of AF, atrial flutter (AFL), and supraventricular tachycardia (SVT) in OHT was 0.33, 2.8%, and 1.3%, respectively. Given that incidence of AF, AFL, and SVT in historical post-CABG population is 25%, 17%, and 4.3%, transplanted patients appear to have lower incidence of AF, AFL, and SVT than the reference population. Consistent with this, transplanted patients underwent few ablation procedures for atrial arrhythmias. Additionally, the three patients with AF had bicaval anastomoses suggesting the possibility of PACs originating in the donor superior vena cava (SVC) or IVC (inferior vena cava) initiating AF in these patients., Conclusions: In a cohort study of transplant and low-risk CABG patients, the strongest independent predictor of freedom from AF is having undergone transplant surgery. One potential explanation for the markedly lower incidence of AF may be effective isolation of thoracic veins with documented cases retaining the native SVC.

Background: Catheter ablation has significantly transformed the clinical management of atrial fibrillation (AF). The safety and efficacy of this procedure are not well understood in patients with pacemakers and defibrillators., Objectives: The purpose of this study was to study the impact of radiofrequency catheter ablation of AF in patients with pacemakers and implantable cardiac defibrillators., Methods: We studied 86 patients with pacemakers and defibrillators (group I) and a similar number of age- and gender-matched controls (group II) who underwent AF ablation between 1999 and 2004. Clinical and procedural variables were compared between the two groups. In group I, various generator and lead parameters were compared before and after the procedure. Resurgence of clinical AF after 2 months was considered recurrence., Results: Both groups were similar with regard to age, gender, body mass index, and type of AF. Group I had a higher incidence of diabetes (17% vs 6%, P = .03), coronary artery disease (25% vs 13%, P = .05), less prolonged AF (31 +/- 21 vs 45 +/- 30 months, P <.001), lower left ventricular ejection fraction (49 +/- 13% vs 52 +/- 9%, P = .03), and left ventricular end-diastolic dimensions (4.97 +/- 0.81 vs 4.72 +/- 0.67, P = .03). No changes in the sensing and pacing thresholds, impedance of atrial and ventricular leads, or defibrillator coil impedance after AF ablation were observed in group I. Atrial lead dislodgment was seen in two patients. Transient abnormal but "expected" pulse generator behavior was seen in 25% of patients without permanent malfunction. Stroke (1% vs 1%, P = 1.000), pulmonary vein stenosis (2% vs 1%, P = .77), and AF recurrence rates at 12 months were similar between groups I and II, respectively (19% vs 21%, P = .73)., Conclusion: AF ablation is safe and efficacious in patients with pacemakers and defibrillators.

Background: The isolation of a pathogen is vital in the diagnosis and treatment of a device infection. A swab culture, despite poor sensitivity, is the most common method used in specimen collection., Objective: To determine the relative value of swab and tissue specimen cultures in patients with implantable cardiac pacemakers and defibrillators., Design: Prospective patient cohort study., Setting: A 1,000-bed tertiary referral center in Cleveland, Ohio., Patients: Consecutive patients with implantable cardiac pacemaker or defibrillator presenting for lead extraction from October 1, 2000 to March 31, 2001., Methods: Tissue and swab cultures were prospectively collected during pacemaker and implantable defibrillator surgeries that required lead extraction. Clinical manifestations, microbiology, and echocardiographic data were recorded in patients with and without a clinical diagnosis of device system infection., Results: Seventy-one patients with implantable pacemaker (n = 49, 69%), implantable defibrillator (n = 18, 25%), or both devices (n = 4, 6%) requiring lead extraction had pocket swab and tissue cultures for analysis. Infection was evident clinically in 35 (49%) of the patients and absent in the remainder. The most common bacteria isolated were coagulase-negative Staphylococcus (37%) and Staphylococcus aureus (10%). Patients with clinical infection had positive cultures more frequently (P = 0.002) by pocket tissue culture (n = 24, 69%) than by swab culture (n = 11, 31%). However, patients without clinical infections had positive cultures at similar rates by pocket tissue culture (n = 10, 28%) and by swab culture (n = 8, 22%; P = 0.48). Patients without clinical infection were not treated with other than perioperative antibiotics, and did not develop clinical infections., Conclusion: Pocket tissue cultures are more effective than pocket swab cultures for the isolation and identification of the infectious pathogens in cardiac device infections. Positive cultures by pocket swab or tissue cultures in the absence of clinical signs and symptoms of infection does not imply infection or the need for specific therapy.

Background: Infection is a devastating complication of permanent pacemakers (PMs) implantable cardioverter defibrillators (ICDs). Many implanting physicians commonly use povidone-iodine solution to irrigate the device pocket before implanting the device. We sought to assess if such a measure would alter the rate of infection., Methods: A total of 2,564 consecutive patients who received implantable PM or ICD devices between 1994 and 2002 were studied. Povidone-iodine was used for pocket irrigation in 53% and saline in 47%. A total of 18 (0.7%) patients developed pocket infections with 0.7% (10/1,359) in povidone-iodine (group I) and 0.6% (8/1,205) in saline (group II) pocket irrigation (p = ns). Groups I and II were studied for various clinical and demographic variables described in the results section., Results: There was no statistical difference in the baseline demographic and clinical characteristics between groups I and II, respectively. ICDs were most frequently infected than PMs (56% vs 44%). Most (83%) of the devices were dual chamber. Reopening of the pocket for either lead or generator replacement had a higher incidence of infection than new implants (61% vs 39%). There was no difference in the use of preimplantation antibiotic prophylaxis. Late (61%) and deep pocket infections (78%) were more common than early (39%) and superficial infections (22%). Blood cultures were positive in 67% and Staphylococcus aureus was the common most pathogen (50%). The mean duration of antibiotics use after the diagnosis of device infection was 35 +/- 23 days with 72% requiring device explantation. The device was reimplanted on the contralateral side in 56% cases. One patient in each group died due to device infection and related complications. No significant allergy to iodine was seen in either group., Conclusion: Povidone-iodine irrigation of the subcutaneous pocket did not alter the rates of pocket infection after pacemaker/defibrillator implantation.

Context: Treatment with antiarrhythmic drugs and anticoagulation is considered first-line therapy in patients with symptomatic atrial fibrillation (AF). Pulmonary vein isolation (PVI) with radiofrequency ablation may cure AF, obviating the need for antiarrhythmic drugs and anticoagulation., Objective: To determine whether PVI is feasible as first-line therapy for treating patients with symptomatic AF., Design, Setting, and Participants: A multicenter prospective randomized study conducted from December 31, 2001, to July 1, 2002, of 70 patients aged 18 to 75 years who experienced monthly symptomatic AF episodes for at least 3 months and had not been treated with antiarrhythmic drugs., Intervention: Patients were randomized to receive either PVI using radiofrequency ablation (n=33) or antiarrhythmic drug treatment (n=37), with a 1-year follow-up., Main Outcome Measures: Recurrence of AF, hospitalization, and quality of life assessment., Results: Two patients in the antiarrhythmic drug treatment group and 1 patient in the PVI group were lost to follow-up. At the end of 1-year follow-up, 22 (63%) of 35 patients who received antiarrhythmic drugs had at least 1 recurrence of symptomatic AF compared with 4 (13%) of 32 patients who received PVI (P<.001). Hospitalization during 1-year follow-up occurred in 19 (54%) of 35 patients in the antiarrhythmic drug group compared with 3 (9%) of 32 in the PVI group (P<.001). In the antiarrhythmic drug group, the mean (SD) number of AF episodes decreased from 12 (7) to 6 (4), after initiating therapy (P = .01). At 6-month follow-up, the improvement in quality of life of patients in the PVI group was significantly better than the improvement in the antiarrhythmic drug group in 5 subclasses of the Short-Form 36 health survey. There were no thromboembolic events in either group. Asymptomatic mild or moderate pulmonary vein stenosis was documented in 2 (6%) of 32 patients in the PVI group., Conclusion: Pulmonary vein isolation appears to be a feasible first-line approach for treating patients with symptomatic AF. Larger studies are needed to confirm its safety and efficacy.

Introduction: Left atrial flutter (LAFL) is a known complication of pulmonary vein isolation. Treatment of this arrhythmia currently involves both linear lesions as well as re-isolation. However, it is unknown if re-isolation alone is sufficient to prevent recurrence. This study reviews the incidence of LAFL following segmental PV antrum isolation (PVAI) in a large patient population and evaluates if re-isolation alone is sufficient to prevent recurrence., Methods and Results: Seven hundred thirty-seven patients underwent PVAI. Twenty-three patients (3.1%) developed post-PVAI LAFL. All patients underwent a second procedure in which only repeat PVAI was done. During the second procedure, all flutter circuits were electroanatomically mapped. All patients were followed at 3, 6, and 12 months. All 23 patients demonstrated recovery in one or more PV. After repeat isolation of the PVs, 61% of patients were arrhythmia free off all antiarrhythmic drugs. A relationship between the presence/absence of pre-existing left atrial (LA) scar was observed. Of the 11 patients with pre-existing LA scar, 36% remained arrhythmia free off antiarrhythmic drugs. In contrast, of the 12 patients without pre-existing LA scar, 83% remained arrhythmia free off antiarrhythmic drugs (P = 0.03)., Conclusion: Among patients with LAFL following PVAI, re-isolation alone is sufficient in preventing recurrence in patients without pre-existing LA scar. Patients with pre-existing LA scar tend to have recurrence requiring further ablation including linear lesions, and continue to need antiarrhythmic medications.

Unlabelled: Dissociated pulmonary vein rhythm., Introduction: Characterization of the electrophysiologic behavior of the pulmonary vein (PV) triggers initiating atrial fibrillation (AF) is still lacking. We conducted the current study to evaluate the behavior of the dissociated PV rhythm (PVD) observed after electrical disconnection from the left atrium of the PV responsible for initiation of AF., Methods and Results: Four hundred and seven consecutive patients (102 women; mean age 55+/-11 years) presented for ablation of symptomatic AF to our laboratory. After isolation, sustained dissociated rhythm (>10 minutes) was documented in 2.1% (34 of 1,568 PVs) of the PVs (initiating AF prior to isolation). Adenosine (18 mg IV bolus), verapamil (10 mg IV bolus), phenylephrine (200 mcg bolus followed by infusion at 100 mcg/hour), and isoproterenol (infusion rate of 15 mcg/hour) were administered in these patients. The cycle length of the PV rhythm before and after the administration of drugs was measured. Adenosine prolonged the sinus node (SN) cycle length (from 750+/-105 to 1,900+/-200 ms; P<0.05) and suppressed the PVD. Isoproterenol shortened both the SN (from 750+/-105 to 420+/-150 ms; P<0.05) and the PVD (from 2,225+/-300 to 800+/-190 ms; P<0.05) cycle length. A similar response to adenosine and isoproterenol of the PV firing was observed prior to isolating the arrhythmogenic PV. Phenylephrine prolonged the cycle length of both the SN (from 740+/-115 to 960+/-90 ms; P<0.05) and the PV rhythm (from 2,200+/-300 to 2,355+/-280 ms; P=0.87). Verapamil did not cause a significant change either in the SN or in the PVD cycle length., Conclusion: Our data suggest that the PVD within isolated PV responsible for initiating AF exhibits a response to pharmacologic agents similar to the SN cells.

Introduction: Sick sinus syndrome is commonly associated with tachyarrhythmias and bradyarrhythmias that often are symptomatic. The aim of this study was to assess the effect of pulmonary vein isolation in patients with sick sinus syndrome and atrial fibrillation (AF)., Methods and Results: Three hundred fourteen consecutive patients who underwent pulmonary vein isolation between December 2000 and January 2002 were included in the study. Thirty-one patients had sick sinus syndrome, which was defined as a preprocedural history of symptomatic sinus bradycardia or pauses. Endpoints included AF recurrence, change in the frequency of sinus pauses, and symptoms of presyncope or syncope, as well as mean heart rate and percentage of atrial pacing in patients with pacemakers implanted prior to the pulmonary vein isolation. Patients had AF for an average of 6 +/- 3 years. Patients were 58 +/-8 years old and had ejection fractions of 55 +/- 4%. Sixty-one percent had implanted pacemakers. AF recurred within 6 months in 4 patients. Two had a successful second pulmonary vein isolation procedure. There were no recurrences of presyncopal events (P < 0.05) or documented sinus pauses (P < 0.05) after successful pulmonary vein isolation in the patients without permanent pacemakers. Patients with pacemakers had a 13-fold reduction in the percentage of atrial pacing (P < 0.05). Both groups showed a significant increase in average heart rates at 6-month follow-up., Conclusion: Cure of AF by pulmonary vein isolation helped resolve the clinical manifestations of sick sinus syndrome, suggesting that the occurrence of AF and/or the associated treatment could be partially responsible for sick sinus syndrome.

Objectives: We report on the initiation of ventricular fibrillation (VF) storm in patients with ischemic cardiomyopathy (ICM) and the results of targeted ablation to treat VF storm., Background: Monomorphic premature ventricular contractions (PVCs) have been shown to initiate VF in patients without structural heart disease., Methods: A total of 29 patients with ICM and documented VF initiation were identified. In 21 patients, VF storm was controlled with antiarrhythmic drugs and/or treatment of heart failure. Eight patients with VF (mean 52 +/- 25 episodes) refractory to medical management required ablation. All patients underwent three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, California), and PVCs were mapped when present. Scarred areas were identified using voltage mapping., Results: Monomorphic PVCs initiated VF in all 29 identified patients. Five of eight patients requiring ablation had frequent PVCs that allowed PVC mapping. The earliest activation site was consistently located in the scar border zone. The PVCs were always preceded by a Purkinje-like potential (PLP). Ablation was successfully performed at these sites. In three patients, infrequent PVCs prevented mapping, but PLPs were recorded around the scar border. Ablation targeting these potentials along the scar border was successfully performed. During follow-up (10 +/- 6 months), one patient had a single VF episode and another developed sustained, monomorphic ventricular tachycardia. There was no recurrence of VF storm., Conclusions: Ventricular fibrillation in ICM is triggered by monomorphic PVCs originating from the scar border zone with preceding PLPs; targeting these PVCs may prevent VF recurrence. In the absence of PVCs, both substrate mapping and ablation appear to be equally effective.

Objectives: The goal of this study was to assess the safety and efficacy of pulmonary vein antrum isolation in patients with moderate valvular heart disease or open-heart surgery and atrial fibrillation (AF)., Background: Valvular heart disease and open-heart surgery are commonly associated with AF and increase the risk of adverse events in AF patients., Methods: A total of 391 consecutive patients who had pulmonary vein antrum isolation performed between December 2000 and December 2002 were screened. A total of 142 of these patients had clinically significant valvular disease or prior cardiac surgery. End points included AF recurrence and pulmonary vein antrum isolation complication rates., Results: Patients with valvular heart disease or prior open-heart surgery were older, had larger left atria and a more advanced New York Heart Association class. They did not differ significantly with respect to gender, but had a longer history of AF. Procedure times were similar between patients with and without valvular heart disease or prior open-heart surgery. After 18 +/- 7 months in the lone AF patients, 11 +/- 5 months in patients with valvular heart disease, and 10 +/- 5 months in patients with prior open heart surgery, there was a trend toward lower recurrence of AF in patients with lone AF who enjoyed a 98% overall cure rate after up to 2 pulmonary vein antrum isolations versus 93% among patients with valvular heart disease (P = .04) and prior open heart surgery (P = .07). Complication rates were comparable between groups., Conclusions: Pulmonary vein antrum isolation is safe and effective in patients with moderate valvular heart disease and the patients who developed AF after open-heart surgery. These results have implications for our understanding of the pathophysiology of AF in patients with moderate valvular heart disease or past cardiac surgery and should be considered when discussing treatment options in these patients.

Objectives: We aimed to determine the safety and efficacy of pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients with impaired left ventricular (LV) systolic function., Background: To date, PVI has been performed primarily in patients with normal LV function. Yet, many AF patients have impaired LV systolic function. The outcomes of PVI in patients with impaired LV systolic function are unknown., Methods: We included 377 consecutive patients undergoing PVI between December 2000 and January 2003. Ninety-four patients had impaired LV function (ejection fraction [EF] <40%), and they comprised the study group. The control group was the remaining 283 patients who had a normal EF. End points included AF recurrence and changes in EF and quality of life (QoL)., Results: Mean EF was 36% in our study group, compared with 54% in controls. After initial PVI, 73% of patients with impaired EF and 87% of patients with normal EF were free of AF recurrence at 14 +/- 6 months (p = 0.03). In the study group, there was a nonsignificant increase in EF of 4.6% and significant improvement in QoL. Complication rates were low and included a 1% risk of pulmonary vein stenosis., Conclusions: Although the AF recurrence rate after initial PVI in impaired EF patients was higher than in normal EF subjects, nearly three-fourths of patients with impaired EF remained AF-free. Although our sample size was nonrandomized, our results suggest PVI may be a feasible therapeutic option in AF patients with impaired EF. Randomized studies with more patients and longer follow-up are warranted.

Introduction: In patients undergoing circumferential isolation of the pulmonary veins with an ultrasound ablation system, we analyzed the temperatures achieved while delivering circumferential ostial lesions in the pulmonary veins. We also reviewed the angiograms obtained during the procedure and identified anatomic variants that could be responsible for ineffective lesion formation., Methods and Results: During the early clinical use in 33 patients, a total of 85 veins were ablated. A mean of 16.9 +/- 12.3 ablations were delivered per patient, and a mean of 6.7 ablations per vein were applied. Entry block was assessed by placing a deflectable octapolar or a circular catheter in the vein. The following anatomic characteristics and technical limitations were identified as possible reasons for ineffective energy delivery: (1) funnel-shaped ostium; (2) ostial diameter larger than the balloon diameter; (3) inability to deliver the catheter to the right inferior or other vein ostia; (4) ostial instability; (5) early branching of the vein; and (6) eccentric position of the ultrasound transducer in the vein. In patients with recurrence of atrial fibrillation, 40% of the ostial lesions reached a temperature >60 degrees C. However, in patients cured by the ablation, 64% of the ostial lesions reached a temperature >60 degrees C (P < 0.06). At least 12 of the 20 chronic recurrences could have been related to technical limitations of the first system. Duration of atrial fibrillation and eccentric deployment of the ultrasound transducer were more frequent in patients with recurrence of arrhythmias at follow-up., Conclusion: Ostial anatomy of the veins may affect delivery of ultrasound energy to achieve circumferential lesions. Energy delivery at the ostium with a temperature > 60 degrees C may be important to maximize success. Reconfiguration of the system to overcome the shortcomings identified in the initial experience could increase its performance.

Objectives: We conducted this study to compare the efficacy and safety of different catheter ablation technologies and of distal versus ostial pulmonary veins (PV) isolation using the circular mapping technique., Background: Electrical isolation of the PVs in patients with atrial fibrillation (AF) remains a technical challenge., Methods: Two hundred eleven patients (163 men; mean age 53 +/- 11 years) with symptomatic AF were included in this study. In the first 21 patients (group 1), distal isolation (> or = 5 mm from the ostium) was achieved targeting veins triggering AF. In the remaining 190 patients (group 2), ostial isolation of all PVs was performed using 4-mm tip (47 patients), 8-mm tip (21 patients), or cooled-tip (122 patients) ablation catheters., Results: Distal isolation was able to eliminate premature atrial contractions (PACs) and AF in six of 21 patients (29%) and 10 of 34 PVs. After a mean follow-up time of 6 +/- 4 months, no patients treated with the 8-mm tip catheter experienced recurrence of AF, whereas 21% (10 of 47 patients) and 15% (18 of 122 patients) of the patients ablated with the 4-mm tip and the cooled-tip ablation catheters experienced recurrence of AF after a mean follow-up of 10 +/- 3 and 4 +/- 2 months, respectively. Significant complications including stroke, tamponade, and severe stenosis occurred in 3.5% (8/211) of patients., Conclusions: Catheter technologies designed to achieve better lesion size appeared to have a positive impact on procedure time, fluoroscopy time, number of lesions, and overall efficacy. Although distal isolation can be achieved with fewer lesions, ostial isolation is required in the majority of patients to eliminate arrhythmogenic PACs and AF.

Introduction: Preliminary data in a heart failure animal model and isolated muscle preparation have suggested that nonexcitatory stimulation (NES) improves left ventricular (LV) function., Methods and Results: We compared biventricular (BV) pacing with NES in an animal model with left bundle branch block (LBBB). The left bundle branch (LBB) was ablated in eight normal heart pigs and led to >50% increase in QRS duration (mean 100 +/- 15 msec). End-diastolic LV pressure, end-systolic LV pressure, LV pressure (LV dP/dtmax), aortic pulse pressure, and LV ejection fraction were measured before pre-LBB ablation and compared with post-LBB ablation (AAI pacing), BV pacing, NES delivery, and BV+NES. Moreover, to evaluate LV diastolic function, we measured the early (E wave) and late flows (A wave) through the mitral valve using spectral Doppler. Compared with post-LBB ablation, NES led to a significant increase in LV dP/dtmax (1,047 +/- 224 mmHg/sec vs 897 +/- 116 mmHg/sec; P < 0.05), LV ejection fraction (64% +/- 18% vs 49% +/- 17%; P < 0.05), and aortic pulse pressure (18 +/- 3.6 mmHg vs 16 +/- 2.8 mmHg; P < 0.05). Moreover, improvement in LV hemodynamic parameters was significantly higher during NES delivery when compared with BV pacing. No significant changes in E wave, A wave, and E/A were recorded during NES, NES+BV, and BV pacing., Conclusion: Our preliminary data demonstrate that NES is superior to BV pacing in improving LV function in an animal model with LBBB. Moreover, we demonstrated that NES does not affect transmitral valve flow and subsequently LV diastolic function.

Objectives: We conducted this study to assess long-term results of three-dimensional (3-D) mapping-guided radiofrequency ablation (RFA) of inappropriate sinus tachycardia (IST). Change in activation after the administration of esmolol was also assessed and compared to the shift documented with successful sinus node (SN) modification., Background: The long-term results after RFA of IST have been reported to vary between 27% and 66%., Methods: Thirty-nine patients (35 women, mean age 31 +/- 9 years) with debilitating IST were included in the study. The area around the earliest site of activation recorded using the 3-D mapping system was targeted for ablation. The shift in the earliest activation site after administration of esmolol was compared with the shift after RFA., Results: The heart rate at rest and in drug-free state ranged between 95 and 125 beats/min (mean 99 +/- 14 beats/min). Sinus node was successfully modified in all patients. Following ablation, the mean heart rate dropped to 72 +/- 8 beats/min, p < 0.01. The extent of the 3-D shift in caudal activation along the crista terminalis was more pronounced after RFA than during esmolol administration (23 +/- 11 mm vs. 7 +/- 5 mm, respectively, p < 0.05). No patient required pacemaker implantation after a mean follow-up time of 32 +/- 9 months; 21% of patients experienced recurrence of IST and were successfully re-ablated., Conclusions: Three-dimensional electroanatomical mapping seems to facilitate and improve the ablation results of IST. The difference in caudal shift seen after esmolol administration and following SN modification suggests that adrenergic hypersensitivity is not the only mechanism responsible for the inappropriate behavior of the SN.

The purpose of this study was to assess the feasibility and long-term results of empirical isolation of both superior pulmonary veins in patients with chronic AF. Although localizing and ablating the focal triggers of AF has been proven an effective approach, this strategy is time consuming, often requires multiple procedures, and carries the risk of pulmonary vein stenosis. Whether ostial electrical isolation of the superior pulmonary veins, without initial detailed mapping, is a more efficient approach is not known. The study included 71 consecutive patients who had chronic AF. Using a nonfluoroscopic electroanatomic mapping system, the left and right superior pulmonary veins were ablated circumferentially at the venoatrial junction, with the aim of achieving electrical isolation of the veins. Following ablation, if frequent atrial ectopies were present, mapping and ablation were considered. The patients were periodically followed with 48-hour Holter and loop recorder monitoring. After the ablation of the right and left superior pulmonary veins 59 (83%) of 71 patients maintained sinus rhythm without premature atrial beats. The remaining 12 patients underwent further mapping and ablation including 5 patients who required isolation of the left inferior pulmonary veins. True electrical isolation could be achieved only in 45 (31%) of the 147 targeted veins. At the latest follow-up (mean 29 +/- 8 months), 80% of the patients with upper vein isolation remained in sinus rhythm off medications, 62% of the patients maintained sinus rhythm on previously ineffective medications, and 17% continued to be in AF. Fourteen (20%) patients developed intermittent episodes of left atrial flutter, and mapping in these patients revealed large electrically silent areas in the left atrium. Empirical isolation of pulmonary veins appeared to be an effective approach to help maintain sinus rhythm in patients with chronic AF. True electrical isolation of the pulmonary veins was associated with a higher likelihood of long-term success. Left atrial flutter was seen in a significant number of patients at long-term follow-up.

Introduction: The efficacy of midodrine for the management of patients with neurocardiogenic syncope was assessed prospectively in a randomized control study., Methods and Results: Patients who had at least monthly occurrences of syncope and a positive tilt-table test were included in the study. A total of 61 patients were randomly allocated to treatment either with midodrine or with fluid, salt tablets, and counseling. Midodrine was given at a starting dose of 5 mg three times a day and increased up to a dose of 15 mg three times a day when required. Midodrine was given during the daytime every 6 hours. Thirty-one patients were assigned to treatment with midodrine; the other 30 patients were advised to increase their fluid intake and were instructed to recognize their prodromes and abort the progression to syncope. Patients were followed-up for at least 6 months. A quality-of-life questionnaire was administered at the time of randomization and 6 months after. At the 6-month follow-up, 25 (81%) of 31 midodrine-treated patients and 4 (13%) of the 30 fluid-therapy patients had remained asymptomatic (P < 0.001). One patient had to discontinue taking midodrine due to severe side effects and another six patients experienced minor side effects that did not require drug discontinuation., Conclusion: Midodrine appeared to provide a significant benefit in patients with neurocardiogenic syncope. To prevent recurrence of symptoms, dose adjustments were required in about one third of patients.

Objectives: To describe a normal heart left bundle branch block, inferior axis ventricular tachycardia (VT), that could not be ablated from the right or left ventricular outflow tracts., Background: Whether these VTs are epicardial and can be identified by a specific electrocardiographic pattern is unclear., Methods: Twelve patients with normal heart left bundle branch block, inferior axis VT and previously failed ablation were included in this study. Together with mapping in the right and left ventricular outflow tracts, we obtained percutaneous epicardial mapping in the first five patients and performed aortic sinus of Valsalva mapping in all patients., Results: No adequate pace mapping was observed in the right and left ventricular outflow tracts. Earliest ventricular activation was noted in the epicardium and the aortic cusps. All patients were successfully ablated from the aortic sinuses of Valsalva (95% CI 0% to 18%). The electrocardiographic pattern associated with this VT was left bundle branch block, inferior axis and early precordial transition with Rs or R in V2 or V3. Ventricular tachycardia from the left sinus had rS pattern in lead I, and VT from the noncoronary sinus had a notched R wave in lead I. None of the patients had complications and all remained arrhythmia-free at a mean follow-up of 8 +/- 2.6 months., Conclusions: Normal heart VT with left bundle branch block, inferior axis and early precordial transition can be ablated in the majority of patients from either the left or the noncoronary aortic sinus of Valsalva.

Atrial premature depolarizations (APDs) originating from focal sites, particularly the pulmonary veins (PV), may become triggers of atrial fibrillation (AF). Accurate mapping of APDs with conventional methods may be time consuming and expose the patient to unnecessary instrumentation of the left atrium. We hypothesized that the atrial activation sequence recorded using a simple system that includes an esophageal catheter and a custom-made 16-electrode catheter with two sets of floating electrodes eight in the coronary sinus and eight in the high right atrium) could be sufficient to localize the APDs. The study included 29 patients with frequent APDs and AF refractory to antiarrhythmic medications. The APD site of origin was confirmed with single-point sequential mapping techniques using the CARTO system ten patients) or by placement of multielectrode catheters in the right and left PV (19 patients). Of the 29 patients, 20 patients had a single APD focus; 8 patients had two different APD morphologies; and 1 patient had three APD foci. Mapping for ablation of the APD foci showed earliest activation in the left superior PV in 12 patients, right superior PV in 15 patients, right middle PV in 4 patients, right inferior PV in 1 patient, the lingular branch of the left superior PV in 2 patients, left inferior PV in 2 patients, and right atrium along the crista terminalis in 3 patients. The activation sequence and relative timing of the recordings obtained with our catheter configuration was highly predictive of right and left atrial origin and, more importantly, of right and left PV foci.

Epicardial location of accessory AV pathways may be responsible for the failure of conventional endocardial radiofrequency catheter ablation. Transcutaneous epicardial instrumentation provides access to the normal pericardium with no need for invasive thoracotomy or thoracoscopy. We report the case of successful epicardial mapping and ablation of a right atrial appendage-ventricular connection using a percutaneous epicardial approach, after repeated failure of endocardial ablation attempts.

Objectives: We sought to determine the yield of in-hospital monitoring for detection of significant arrhythmia complications in patients starting sotalol therapy for atrial arrhythmias and to identify factors that might predict safe outpatient initiation., Background: The need for hospital admission during initiation of antiarrhythmic therapy has been questioned, particularly for sotalol, with which proarrhythmia may be dose related., Methods: The records of 120 patients admitted to the hospital for initiation of sotalol therapy were retrospectively reviewed to determine the incidence of significant arrhythmia complications, defined as new or increased ventricular arrhythmias, significant bradycardia or excessive corrected QT (QTc) interval prolongation., Results: Twenty-five patients (20.8%) experienced 35 complications, triggering therapy changes during the hospital period in 21 (17.5%). New or increased ventricular arrhythmias developed in 7 patients (5.8%) (torsade de pointes in 2), significant bradycardia in 20 (16.7%) (rate <40 beats/min in 13, pause >3.0 s in 4, third-degree atrioventricular block in 1, permanent pacemaker implantation in 3) and excessively prolonged QTc intervals in 8 (6.7%) (dosage reduced or discontinued in 6). Time to the earliest detection of complications was 2.1 +/- 2.5 (mean +/- SD) days after initiation of sotalol, with 22 of 25 patients meeting criteria for complications within 3 days of monitoring. Baseline electrocardiographic intervals or absence of heart disease failed to distinguish a low risk group. Multivariate analysis identified absence of a pacemaker as the only significant predictor of arrhythmia complications (p = 0.022)., Conclusions: Because clinically significant complications can be detected with in-hospital monitoring in one of five patients starting sotalol therapy, hospital admission is warranted for initiation of sotalol. Patients without pacemakers are at higher risk for these complications.

Patients with malignant arrhythmias are a challenge when they present to the laboratory for exercise testing and training. The complex metabolic and electrophysiological changes that occur during and after exercise may suppress or potentiate arrhythmias and alter the efficacy and safety of antiarrhythmic agents. The presence of an ICD adds a level of complexity to the study; however, a general understanding of how ICDs function and a review of the programmed parameters before the study will result in a lesser likelihood of complication and more efficient and appropriate action, should a complication occur. Exercise testing and training are valuable methods for the evaluation and treatment of patients with malignant ventricular arrhythmias. Exercise testing is a useful adjunctive technique in the exposure of arrhythmia and the evaluation of the efficacy and proarrhythmic potential of antiarrhythmic agents. These patients are excellent candidates for rehabilitation and exercise training programs, which may result in increased functional capacity and improved quality of life. With this knowledge and adherence to the appropriate guidelines for patient selection and testing, exercise testing and training of patients with malignant arrhythmias can be prescribed and conducted in a safe, controlled manner in an atmosphere of confidence and professionalism.