Reducing Door-in Door-out Intervals in Helicopter ST-segment Elevation Myocardial Infarction Interhospital Transfers.

BACKGROUND: Many health systems rely on helicopter EMS (HEMS) to transfer ST-elevation myocardial infarction (STEMI) patients for percutaneous coronary intervention (PCI) to a hospital with a catheterization laboratory. Mortality rates increase with the time to reperfusion, so reducing delays is imperative. For interhospital STEMI transfers, the time spent in the initial hospital from arrival until departure (door-in to door-out interval or DIDO) should be minimized. OBJECTIVE: To evaluate the impact of a series of process improvements to reduce DIDO intervals for STEMI patients transferred via a hospital based HEMS program. METHODS: Changes made to the STEMI transfer protocol in March 2011 were: (a) allowing transferring facilities to request HEMS before identifying an accepting cardiologist or hospital, with one hospital serving as a default PCI center in the case of delays, (b) limiting continuous infusions to those absolutely necessary for the transfer flights and (c) training flight crews to minimize time at bedside. Trained dual abstractors conducted structured medical record reviews for all STEMI patients 18 years and older, transferred to a PCI facility by HEMS from March 2011 to December 2012. Discrepancies were adjudicated. We compared DIDO intervals to a historical control cohort from 2007. We used the Mann-Whitney U test to compare times, and calculated differences with 95% confidence intervals. RESULTS: Of 244 patients identified, six were excluded due to incomplete data. The historical cohort included 179 cases. Mean age was 59 (SD 14) years, 81% were white and 66% male. There were no differences in patient characteristics or door to EKG times between the cohorts. Median door-in to door-out interval decreased from 83 minutes (IQR 43) to 68 minutes (IQR 31) (difference 15 minutes, 95% CI 8 to 21, P <.0001). EKG to HEMS request decreased 21 minutes (95% CI 17 to 25, P <.0001), and HEMS ground time decreased 3 minutes (95% CI 2 to 4, P <.0001). There was a 32% absolute increase in the proportion of patients with EKG to helicopter request interval <35 minutes (83% vs 51%, difference 32%, 95% CI 24% to 41%, P <.0001). CONCLUSION: HEMS-focused process improvements can significantly reduce the DIDO interval times for STEMI patients transferred for PCI.

S100 and CD34 Expressing Mesenchymal Neoplasm With Rare PLEKHH2::ALK Fusion and Response to ALK Inhibition.

The PLEKHH2::ALK fusion is a rarely reported gene fusion identified predominantly in lung adenocarcinomas. Tumors with this fusion have been reported to be of durable response to ALK inhibitors. We herein present the case of a 21-year-old woman with a histomorphologically heterogenous mesenchymal neoplasm of the pelvis, expressing both s100 and CD34, with subsequently identified PLEKHH2::ALK fusion. To our knowledge, only a single mesenchymal neoplasm with this gene fusion has been previously reported. We propose that this tumor represents one with a novel ALK fusion in the emerging family of s100 and CD34 expressing mesenchymal neoplasms with oncogenic kinase alterations akin to NTRK -rearranged mesenchymal neoplasms, rather than inflammatory myofibroblastic tumor. Importantly, this tumor demonstrated a significant response to the ALK inhibitor brigatinib.

A1 Pulley Tenderness as a Modification to Tenderness along the Flexor Sheath in Diagnosing Pyogenic Flexor Tenosynovitis.

Background: Pyogenic flexor tenosynovitis (PFT) is frequently diagnosed by physical examination according to the Kanavel signs. This study proposes a modification of the Kanavel sign "tenderness over the course of the flexor sheath" by including palpation of the A1 pulley to increase specificity for diagnosis. Methods: A retrospective review was performed over 8 months for patients in the emergency department who received a consult to hand surgery to rule out PFT. Two cohorts, nonPFT infections and PFT infections, were studied for the presence or absence of the four Kanavel signs, as well as tenderness specifically over the A1 pulley on the affected digit(s) or T1 pulley of the thumb. Results: There were a total of 33 patients in the two cohorts (21 nonPFT, 12 PFT) with statistically significant differences with regard to the presence of all the Kanavel signs. A1 pulley tenderness had the greatest odds ratio, positive predictive value, specificity, and accuracy when compared with all Kanavel signs. When used in conjunction with each Kanavel sign, there was an increase in specificity in all four signs. Receiver operating characteristic analysis revealed increased area under the curve with A1 pulley tenderness added, indicating improved ability to classify hand infections as PFT versus nonPFT. Conclusion: Although the classic Kanavel signs have shown reliable clinical utility, this study finds that tenderness at the A1 pulley can be a useful specification of "tenderness over the course of the flexor sheath" to help with the diagnosis of PFT.

Cryoballoon ablation of paroxysmal atrial fibrillation within the dilated coronary sinus in a case of persistent left superior vena cava.

Trigger sources of paroxysmal atrial fibrillation (PAF) are not limited to a pulmonary vein origin and may be achievable by cardiac vascular structures like the coronary sinus (CS), the vena cava superior and in some rare cases by a persistent left superior vena cava (LSVC). Cryoballoon ablation has been shown to be effective in pulmonary vein isolation. We report an unusual case of using this technique in the dilated CS in case of a persistent LSVC. A 64 year old patient presented PAF recurrences after cryo pulmonary vein isolation 4 months before. A maintaining pulmonary vein isolation could be demonstrated by transseptal mapping. Further bi-atrial mapping localized repetitive atrial trigger activity in a dilated CS proceeding to a LSVC. A cryoballoon was deployed in the CS target area and during cryoablation the triggered activity suspended. Ablation side effects were excluded by coronary angiography. During a follow up time of 8 months the patient has remained free of PAF recurrences. The current report underlines the importance of a patient-tailored ablation approach. Cryothermic balloon technology may be more applicable in delicate cardiac structures by developing new anatomically adapted balloon shapes and sizes.

Fibroblast growth factor 21 corrects obesity in mice.

Fibroblast growth factor 21 (FGF21) is a metabolic regulator that provides efficient and durable glycemic and lipid control in various animal models. However, its potential to treat obesity, a major health concern affecting over 30% of the population, has not been fully explored. Here we report that systemic administration of FGF21 for 2 wk in diet-induced obese and ob/ob mice lowered their mean body weight by 20% predominantly via a reduction in adiposity. Although no decrease in total caloric intake or effect on physical activity was observed, FGF21-treated animals exhibited increased energy expenditure, fat utilization, and lipid excretion, reduced hepatosteatosis, and ameliorated glycemia. Transcriptional and blood cytokine profiling studies revealed effects consistent with the ability of FGF21 to ameliorate insulin and leptin resistance, enhance fat oxidation and suppress de novo lipogenesis in liver as well as to activate futile cycling in adipose. Overall, these data suggest that FGF21 exhibits the therapeutic characteristics necessary for an effective treatment of obesity and fatty liver disease and provides novel insights into the metabolic determinants of these activities.

Automatic magnetic-guided electroanatomical mapping and remote-controlled ablation of atypical and typical atrial flutter.

UNLABELLED: Two patients with inconclusive surface electrocardiogram patterns underwent nonfluoroscopy automatic mapping and remote-controlled ablation of nonisthmus and isthmus-dependent right atrial flutter. METHODS AND RESULTS: A 0.08 magnetic vector force and a motor drive enable a complex steering of a new 8-mm magnet tip electrode. The navigation system performs atrial electroanatomical mapping fully automatically. Total procedural fluoroscopy time for ablation of nonisthmus-related atypical and isthmus-dependent flutter was 8.5 and 3.2 minutes, respectively. CONCLUSION: Automatic electroanatomical mapping offers a promising option to effectively guide the remote-controlled ablation of atrial reentry tachycardias and to reduce fluoroscopy time.

Rapid quantitative analysis of monoclonal antibody heavy and light chain charge heterogeneity.

An alternative method to traditional 2-dimensional gel electrophoresis (2D-PAGE) and its application in characterizing the inherent charge heterogeneity of chromatographically isolated monoclonal antibody heavy and light chains is described. This method, referred to as ChromiCE, utilizes analytical size-exclusion chromatography (SEC), performed under reducing and denaturing conditions, followed by imaged capillary isoelectric focusing (icIEF) of the chromatographically separated heavy and light chains. Under conditions suitable for the subsequent icIEF analysis, the absolute and relative SEC elution volumes of the heavy and light chains were found to be highly pH dependent, a phenomenon that can be exploited in optimizing chromatographic separation. Compared to 2D-PAGE, the ChromiCE method substantially decreases the time and labor needed to complete the analysis, improves reproducibility, and provides fully quantitative assessment of charge heterogeneity. The ChromiCE methodology was applied to a set of diverse monoclonal antibodies to demonstrate suitability for quantitative charge variant analysis of heavy and light chains. A typical application of ChromiCE in extended characterization and stability studies of a purified antibody is shown.

Circumferential mapping and electric isolation of pulmonary veins in patients with atrial fibrillation.

Information about the clinical efficacy and complications of the circumferential mapping and isolation of the pulmonary veins (PVs) in patients with atrial fibrillation (AF) is still limited. The present study included 75 patients (mean age 58 +/- 11 years, 20 women) with paroxysmal (n = 69) or persistent AF (n = 6). Mapping of PVs was performed with a circumferential mapping catheter. After preferential PV-left atrium (LA) electric inputs were defined, radiofrequency ablation was performed until complete isolation of the PVs from the LA was achieved. A total of 226 PVs were mapped; 195 (86%) showed typical PV potentials. Complete isolation of PVs from the LA was achieved in 173 PVs (89%). Detailed follow-up, including 7-day Holter monitoring at 1, 4, 9, and 12 months after intervention was performed. If AF reoccurred, PVs were mapped and reisolated. After a mean follow-up period of 230 +/- 133 days, 38 of 75 patients (51%) were in sinus rhythm. At 1, 4, and 9 months of follow-up, 31 of 65 patients (48%), 36 of 53 patients (68%, p = 0.04 as compared with the first month), and 21 of 28 patients (75%, p = 0.025 as compared with the first month), respectively, were in sinus rhythm. During follow-up, 30 patients (40%) underwent a second ablation procedure due to recurrence. Recurrences were related to resumption of PV muscle-left atrial conduction (27 patients) and/or extra PV foci (12 patients) or nonablated PVs (8 patients). Complications occurred in 17 patients (22%). PV stenosis was detected in 13 patients (25% to 50% in 7 patients and >50% in 6 patients). Pericardial effusion occurred in 4 patients. It was concluded that isolation of the PV from the LA is moderately effective in the prevention of AF recurrence and could be associated with serious acute and long-term complications.

Electrophysiologic characteristics of the spontaneous onset and termination of atrial fibrillation.

Electrophysiologic characterization of the onset and termination of atrial fibrillation (AF) is poorly defined. Our study population consisted of 21 consecutive patients (mean age 58 +/- 9 years, 6 women) with intermittent (10 patients) or persistent (11 patients) AF. Mapping of the left atrium (LA) and the right atrium (RA) during initiation and termination of AF was performed with a 64-electrode basket catheter. A total of 92 spontaneous AF onsets (in 16 patients) and 63 spontaneous AF terminations were analyzed. Irrespective of the origin of the triggering atrial premature complex (APC), the onset of AF was preceded by an intermediary rhythm that consisted of repetitive firing from the focus that generated the initial APC, reentry around the mitral annulus, or typical atrial flutter. The earliest fibrillatory activity was constantly produced by circumvented regions (generators) localized most frequently in the posterior wall of the LA. Generators of fibrillatory activity were not observed in the RA for any of the patients. In the RA, AF is maintained by a mixture of macro-reentry and driving wave fronts of left atrial origin. Four modes of AF termination were observed: a multifocal rhythm (19 episodes, 30%), left atrial tachycardia (17 episodes, 27%), direct conversion to sinus rhythm (15 episodes, 24%), and conversion to typical atrial flutter (12 episodes, 19%). A repetitive rapid rhythm initiated most often by APCs plays a crucial role in the initiation of AF via activation of the generators of fibrillatory activity. The LA plays a central role in the initiation of AF by serving as a substrate for generators of fibrillatory activity. Termination of AF consists of a heterogenous group of unstable rhythms.

Simultaneous multisite endocardial mapping of sustained and non-sustained atrial fibrillation in humans.

The aim of this study was to investigate the differences between sustained and non-sustained forms of human atrial fibrillation (AF) using multielectrode endocardial recordings. Methods. Sixty-four pole basket catheters were deployed in the right atrium (RA) of 3 groups of patients: 1) patients with persistent AF (> 48 hours); 2) induced sustained AF (> 15 minutes); and 3) induced non-sustained AF (< 15 minutes). Beat to beat AF intervals (FF) were evaluated for each bipole. On the basis of signal characteristics and direction of wavefront propagation, the degree of spatial and temporal organization of AF was assessed. Results. Persistent AF showed the shortest FF intervals (161 ms) and lowest overall degree of AF organization, induced non-sustained AF the longest FF intervals (192 ms) and highest degree of organization. FF intervals of induced sustained AF were only slightly longer (169 ms) compared to persistent AF. Within each AF group, the lateral wall showed the highest degree of organization, the septal region the lowest. Conclusion. In humans, FF interval and overall degree of AF organization were found to increase significantly from sustained to non-sustained AF. Persistent and induced sustained AF, however, only slightly differed in these parameters.

Fundamentals of FGF19 & FGF21 action in vitro and in vivo.

Fibroblast growth factors 19 (FGF19) and 21 (FGF21) have emerged as key regulators of energy metabolism. Several studies have been conducted to understand the mechanism of FGF19 and FGF21 action, however, the data presented has often been inconsistent and at times contradictory. Here in a single study we compare the mechanisms mediating FGF19/FGF21 actions, and how similarities/differences in actions at the cellular level between these two factors translate to common/divergent physiological outputs. Firstly, we show that in cell culture FGF19/FGF21 are very similar, however, key differences are still observed differentiating the two. In vitro we found that both FGF's activate FGFRs in the context of ßKlotho (KLB) expression. Furthermore, both factors alter ERK phosphorylation and glucose uptake with comparable potency. Combination treatment of cells with both factors did not have additive effects and treatment with a competitive inhibitor, the FGF21 delta N17 mutant, also blocked FGF19's effects, suggestive of a shared receptor activation mechanism. The key differences between FGF21/FGF19 were noted at the receptor interaction level, specifically the unique ability of FGF19 to bind/signal directly via FGFR4. To determine if differential effects on energy homeostasis and hepatic mitogenicity exist we treated DIO and ob/ob mice with FGF19/FGF21. We find comparable efficacy of the two proteins to correct body weight and serum glucose in both DIO and ob/ob mice. Nevertheless, FGF21 and FGF19 had distinctly different effects on proliferation in the liver. Interestingly, in vivo blockade of FGF21 signaling in mice using ΔN17 caused profound changes in glycemia indicative of the critical role KLB and FGF21 play in the regulation of glucose homeostasis. Overall, our data demonstrate that while subtle differences exist in vitro the metabolic effects in vivo of FGF19/FGF21 are indistinguishable, supporting a shared mechanism of action for these two hormones in the regulation of energy balance.

Magnetic-guided percutaneous coronary intervention enabled by two-dimensional guidewire steering and three-dimensional virtual angioscopy: initial experiences in daily clinical practice.

AIMS: Percutaneous coronary intervention (PCI) has been broadly established and often includes highly complex stenoses that require difficult navigation. The purpose of this study is to assess the feasibility of a new magnetic navigation system (MNS) to enable intracoronary guidewire deployment and PCI in daily clinical practice and to compare the 2D guidance to the virtual 3D angioscopy feature. METHODS AND RESULTS: We included 30 consecutive patients (pt) in whom 36 coronary arteries were PCI targets. Patients were randomized to guidewire steering by either 2D guidance or virtual 3D angioscopy (33%). In 31/36 (86%) interventions the MNS guidewire successfully passed the culprit stenosis and the procedure was accomplished by PCI. In 5/30 pt an MNS multivessel intervention was performed. Three of 5 unsuccessful procedures failed due to an unsuccessful recanalization of a subtotal chronic occlusion including 1 pt who required surgical intervention. In 2/36 procedures the magnetic guided intervention was performed effectively after prior conventional failure related to complex anatomy. The contrast medium amount needed to position the magnetic guidewire was 60 +/- 101 mL in 2D accomplished interventions vs. 14 +/- 15 mL in 3D procedures (p < 0.05). In 3 pt the MNS did not harm the implanted pacemaker or defibrillator system. CONCLUSION: Magnetic guided PCI is useful in selected patients. In our experience, success is less likely in evidence of a subtotal occlusion.

Circumferential pulmonary vein isolation with the cryoballoon technique results from a prospective 3-center study.

OBJECTIVES: The purpose of this study was to investigate the efficacy safety of the novel cryoballoon device (Arctic Front, Cryocath, Quebec, Canada). BACKGROUND: Antral pulmonary vein (PV) ablation with radiofrequency energy is widely used as a strategy for catheter ablation of paroxysmal atrial fibrillation (PAF). A novel double lumen cryoballoon catheter was designed for circumferential pulmonary vein isolation (PVI) with the cryoablation technique. METHODS: We consecutively enrolled 346 patients with symptomatic, drug refractory paroxysmal (n = 293) or persistent (n = 53) atrial fibrillation (AF). In all patients, PVI of all targeted PVs was the therapeutic aim. The primary end points of this nonrandomized study were: 1) acute isolation rate of targeted PV; and 2) first electrocardiogram-documented recurrence of AF. The secondary end point was occurrence of PV stenosis or atrio-esophageal fistula. RESULTS: The 1,360 of 1,403 PVs (97%) were targeted with balloons or balloons in combination with the use of Freezor Max (Cryocath). We found that ablation with the cryoballoon resulted in maintenance of sinus rhythm in 74% of patients with PAF and 42% of patients with persistent AF. No PV narrowing occurred. The most frequent complication was right phrenic nerve palsy observed during cryoballoon ablation at the right superior PV. CONCLUSIONS: Pulmonary vein isolation with a new cryoballoon technique is feasible. Sinus rhythm can be maintained in the majority of patients with PAF by circumferential PVI using a cryoballoon ablation system. Cryoablation was less effective in patients with persistent AF than in patients with PAF.

Lack of impact of myocardial ischemia on the signal-averaged ECG assessment by time-domain analysis.

BACKGROUND: Late potentials represent an arrhythmogenic substrate in chronically infarcted myocardium. It is hypothesized that acute transient ischemia enhances anisotropic electrical ventricular activation and facilitates reentry mechanisms. Study aim was the prospective assessment of the impact of dipyridamole-induced myocardial ischemia on the signal-averaged ECG. METHODS: Dipyridamole stress thallium-201 SPECT imaging was utilized to avoid noise contamination of the signal-averaged ECG from exercise and to document evidence and localization of myocardial ischemia or persistent perfusion defects in 68 patients with suspected coronary artery disease. Before and during dipyridamole-induced vasodilatation serial signal-averaged ECG was performed to evaluate the influence of transient ischemia on the occurrence of late potentials. RESULTS: There was a significant difference between heart rate at rest and heart rate under dipyridamole influence in patients with inducible ischemia (70 +/- 13 vs. 87 +/- 13; P < 0.0001) in contrast to patients without dipyridamole-induced ischemia (74 +/- 20 vs. 80 +/- 16; n.s.). The number of averaged beats and achieved noise level was comparable between both groups. Thirty-three of 68 patients (49%) revealed dipyridamole-induced ischemia; however, no changes of the SAECG parameters, such as QRS, RMS, LAS at 25-250 and 40-250 Hz bandpass filtering in the leads X, Y, Z and vector magnitude, respectively, were observed as a result of ischemia. CONCLUSION: These results suggest that transient myocardial ischemia does not affect the signal-averaged ECG. Clinically, the signal-averaged ECG analysis seems not to be helpful in identifying patients with silent ischemia.

Influence of high-pass filtering on noncontact mapping and ablation of atrial tachycardias.

The aim of the study was to define the impact of different high-pass filter settings (HPF) on the accuracy of mapping of ectopic atrial tachycardias (EAT) using a noncontact mapping (NCM) system. In 20 patients with 22 EAT a noncontact probe was deployed in the right (n = 19) or in the left atrium (n = 3). The device enables interpolation and analysis of unipolar electrograms. It provides information on focus localization and signal morphology. These parameters were compared in different HPF of 0.5 Hz, 2 Hz, 8 Hz, and 16 Hz. The NCM signal morphology was preserved at all HPF. An initial negative deflection recorded by NCM system showed a positive predictive value of 93% regarding the ablation success. The deviation (spatial disparity) between visualized focus origin and successful ablation site was 6.9 +/- 5.4 mm. Between two consecutive filter settings, the focus shift was more pronounced between 0.5 and 2 Hz (5.4 +/- 4.5 mm) compared to a setting between 8 and 16 Hz (2.9 +/- 2.9 mm; P < 0.05). Successful ablation was achieved in 15/18 right atrial tachycardias (83%) and in 2/3 left atrial arrhythmias. Different HPF influence NCM spatial analysis of EAT. However, a small variability in foci localization does not impact final ablation results.

Impact of atrial fibrillation on the voltage of bipolar signals acquired from the left and right atria.

A detailed analysis of the impact of atrial fibrillation (AF) on the voltage of the atrial signals acquired from various right and left atrial regions has not been reported. Thirteen patients (mean age 55 +/- 11 years, range 39-67 years, 5 women) with AF were included in this study. Mapping of the left and the right atrium was performed with 64-electrode basket catheters. AF cycle lengths were calculated over 10-second time intervals using a custom-made software. Voltage of the bipolar signals during AF was calculated by measuring the amplitudes of 30 consecutive signals in the left and the right atria. During sinus rhythm voltage differences between the left (3 +/- 2.9 mV) and the right atrium (2.8 +/- 2.4 mV, P = 0.15) were insignificant. During AF, as compared to sinus rhythm, voltages of the bipolar signals were significantly reduced in the left (0.9 +/- 0.6 mV) and the right (1.3 +/- 1.1 mV) atria (P < 0.001 compared with sinus rhythm). In the left atrium, the posterior wall showed the most pronounced voltage reduction (1.1 +/- 0.8 mV vs 5.3 +/- 4.6 mV, P < 0.001). In the right atrium the septal wall showed the greatest reduction in voltage amplitude (0.8 +/- 0.6 mV vs 2.5 +/- 1.5 mV, P < 0.001). There was a close correlation between the voltage values and the AF cycle length. The smallest voltage values and greatest amplitude reductions were observed during faster and more disorganized AF activity. It is concluded that during AF, the voltage of bipolar signals is significantly reduced as compared to sinus rhythm. The reduction in voltage expresses atrial and regional disparity and correlates strongly with local AF cycle lengths and the degree of AF disorganization.

Single chamber atrial fibrillation involving only the left atrium: implications for maintenance and radiofrequency ablation therapy.

Due to the anatomic and the functional interatrial relationship, AF is a biatrial process. Whether one of the atria could sustain AF is not known. This study included 11 patients (mean age 57 +/- 10 years, 7 men) with AF who showed a distinct activation pattern, characterized by regular activity in the right atrium (RA) and irregular fibrillatory activity confined to the left atrium (LA) throughout the AF episodes. Each of the atria was mapped with 64-electrode basket catheters. AF was monitored for 74 +/- 26 minutes. Complex and irregular activity with a cycle length of 138 +/- 43 ms was observed in the LA throughout the monitoring time. The posterior and the roof of the LA showed the highest degree of disorganization. RA was activated by regular wavefronts with a cycle length of 194 +/- 22 ms (P < 0.001, compared with LA). No fibrillatory activity was observed in the RA. All wavefronts that activated the RA were of septal origin: high anteroseptal 52%, low posteroseptal 22%, mid-septal 18, and dual wavefronts (from the high anteroseptal and low posteroseptal pathways) 8%. The lateral wall of the RA was activated in a superoinferior direction in 82% of all activations. A left-to-right conduction block during AF and a rotor of fibrillatory activity located in the posterior wall of the LA were observed in two patients. Isolated AF in the LA showed various surface electrocardiographic patterns. It is concluded that LA alone without participation of the RA can sustain AF. These data have implications for mechanisms and the ablative therapy of AF.

Pulmonary vein internal electrical activity does not contribute to the maintenance of atrial fibrillation.

Whether the electrical activity generated in the pulmonary veins (PVs) during atrial fibrillation (AF) contributes to the maintenance of arrhythmia is not known. The study population consisted of 22 patients (mean age 58 +/- 9.5 years, 16 men) with persistent (12 patients) or intermittent (10 patients) AF. Mapping of the left atrium (LA) was performed with a 64-electrode basket catheter. PVs were mapped simultaneously with the LA with a quadripolar catheter. PV were defined as arrhythmogenic (if frequent ectopic activity induced AF) or nonarrhythmogenic (if no ectopic activity was observed during the procedure). AF cycle lengths in arrhythmogenic and nonarrhythmogenic PV were 130 +/- 50 ms and 152 +/- 42 ms, respectively (P < 0.001). Both were significantly longer than simultaneous AF activity recorded from the posterior wall of the LA (116 +/- 49 ms, P < 0.001). AF cycle lengths in arrhythmogenic PVs as compared to nonarrhythmogenic PVs were: right superior PV 125 +/- 49 ms versus 148 +/- 51 ms; left superior PV 140 +/- 52 ms versus 161 +/- 30 ms; left inferior PV 127 +/- 48 ms versus 147 +/- 45 ms; and right inferior PV 129 +/- 38 versus 152 +/- 44 ms (P < 0.001 for all four comparisons). AF activity in the PV was more organized than in the posterior wall of the LA and the veins were activated in a proximal-to-distal direction during sustained AF episodes. In patients with AF not related to rheumatic heart disease, the posterior wall of the LA has faster activity than the PVs. The AF activity generated inside the PV during sustained AF episodes originates from the posterior wall of the LA rather than from focal firing.

Prospective randomized comparison of closed cooled-tip versus 8-mm-tip catheters for radiofrequency ablation of typical atrial flutter.

INTRODUCTION: Cooled-tip and 8-mm-tip catheters have been found to be more effective than conventional 4-mm-tip catheters for radiofrequency (RF) ablation of common atrial flutter. The aim of this study was to compare the efficacy and safety of cooled-tip and 8-mm-tip catheters for flutter ablation in a randomized, prospective study. METHODS AND RESULTS: In 100 consecutive patients referred for ablation of common atrial flutter, cavotricuspid ablation was performed with a closed cooled-tip catheter (n = 50) or an 8-mm-tip ablation catheter (n = 50). RF current was applied for 60 to 120 seconds at powers of 40 to 50 W with the closed cooled-tip catheter and in a temperature-controlled mode (65 degrees C/70 W) with the 8-mm-tip catheter. The endpoint was achievement of a bidirectional isthmus conduction block. Cross-over was performed after 15 unsuccessful RF applications for each of the catheters. Complete bidirectional isthmus block was achieved in 99% of patients. Cross-over was performed in 11 patients after primary use of the cooled-tip catheter and in 9 patients after primary ablation with the 8-mm-tip catheter. No significant differences were found in the procedure parameters, such as overall RF applications (12.4 +/- 11.3 vs 12.9 +/- 8.6), ablation duration (42 +/- 43 min vs 39 +/- 27 min), and fluoroscopy time (17.0 +/- 18.7 min vs 15.7 +/- 10.7 min). In a mean follow-up of 8.3 months, 1 patient in the cooled-tip group and 3 patients in the 8-mm-tip group had recurrence of common atrial flutter. CONCLUSION: Use of the closed cooled-tip ablation catheter and the 8-mm-tip catheter have equal and high efficacy for RF ablation of common atrial flutter.