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Objective: High power short duration (HPSD) ablation strategy is proposed to be more effective than low power long duration (LPLD) for radiofrequency ablation of atrial fibrillation. Although small trials abound, data from a large cohort are lacking. This meta-analysis compares all the existing studies comparing these two approaches to evaluate perceived advantages of one over the other. Methods: A systematic search of PubMed, EMBASE, and Cochrane databases identified studies comparing HPSD to LPLD ablation. All the analyses used the random-effects model. Results: Ablation settings varied widely across 20 studies comprising 2,136 patients who underwent HPSD and 1,753 patients who underwent LPLD. The pooled incidence of atrial arrhythmia recurrence after HPSD ablation was 20% [95% confidence interval (CI): 0.16–0.25; I2=88%]. Atrial arrhythmia recurrences were significantly less frequent with HPSD ablation (incidence risk ratio=0.66; 95% CI: 0.49–0.88; I2=72%; p=0.004). Procedural, fluoroscopy, and ablation times were significantly shorter with HPSD ablation. First-pass pulmonary vein isolations (PVIs) were significantly more [odds ratio (OR)=2.94; 95% CI: 1.50–5.77; I2=89%; p=0.002), and acute pulmonary vein reconnections (PVRs) were significantly lesser (OR=0.41; 95% CI: 0.28–0.62; I2=62%; p<0.001) in the HPSD group. Although radiofrequency energy was significantly higher, esophageal thermal injuries (ETI) were lower with HPSD ablation. Acute complications, including steam-pops, were rare and statistically similar in both the groups. Conclusion: HPSD ablation enables faster first-pass PVI with fewer PVRs, similar ETI rates, rare collateral damage, and lower recurrence of atrial arrhythmia in the long term than LPLD. Randomized controlled studies with a larger cohort are indicated both to confirm the benefit of HPSD ablation and standardize the ablation protocol. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation is an effective treatment for ventricular arrhythmia (VA) in ischemic cardiomyopathy (ICM). However, results in non‐ICM (NICM) patients are not satisfactory, and studies comparing differences between NICM and ICM are limited. We conducted a meta‐analysis of procedural characteristics and long‐term outcomes of catheter ablation for VA, comparing results between ICM and NICM. Methods: Studies in the PubMed, EMBASE, and Cochrane databases were systematically reviewed. Four studies reporting comparison of catheter ablation of VA between ICM and NICM were examined. The Newcastle‐Ottawa Scale was used to appraise study quality. A random‐effects model with inverse variance method was used for comparisons. Results: Epicardial approach was significantly more undertaken for the NICM group than in the ICM group (odds ratio [OR]: 0.13; 95% confidence interval [CI]: 0.09‐0.18; P <.00001). Mean ablation time (P =.54), fluoroscopy time (P =.55), and procedural time (P =.18) did not differ significantly between the ICM and NICM groups. Procedural failure rates (OR: 0.46; 95% CI: 0.24‐0.89; P =.02) and VA recurrence rates (risk ratio [RR]: 0.68; 95% CI: 0.46‐1.01; P =.06) were significantly higher in the NICM group than in the ICM group. However, all‐cause mortality (RR: 1.37; 95% CI: 0.75‐2.49; P =.31) did not differ significantly between groups. Conclusions: Procedural failure and VA recurrence rates were significantly higher in the NICM group, despite significantly more frequent epicardial access. These highlight the limitations of catheter ablation for VA in NICM, given our current knowledge. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping‐system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow‐pathway identification, and ablation become increasingly important. We present a novel method of slow‐pathway identification and initial ablation results from this method. Methods and Results: We examined AVNRT ablations performed at our institution over a 12‐month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow‐up (median, day 51), one patient had lower‐extremity deep‐vein thrombosis and pulmonary embolus, and one had a lower‐extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation. Conclusions: Mapping‐system detection of late‐activation, low‐amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT. [ABSTRACT FROM AUTHOR]

Introduction Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle. Methods An ovine model (n = 3) was used in this proof-of-concept study. A decapolar catheter was used to collect bipolar impedance readings; data were collected between each of five electrode pairs of varying distances. Data were collected from three test regions: the pericardial space, anterior mediastinum, and right ventricle. A control region in the inferior vena cava was used to normalize the data from the test regions. Analysis of variance was used to test for differences among regions. Results A total of 10 impedance values were collected in each animal between each of the five electrode pairs in the three test regions (n = 340) and the control region (n = 145). The average normalized impedance values were significantly different among the pericardial space (1.760 ± 0.370), anterior mediastinum (3.209 ± 0.227), and right ventricle (1.024 ± 0.207; P < 0.0001). In post hoc testing, the differences between each pair of regions were significant, as well (P < 0.001 for all). Conclusion Impedance values are significantly different among these three anatomical compartments. Therefore, impedance can be potentially used as a means to guide percutaneous epicardial access. [ABSTRACT FROM AUTHOR]

Introduction: Current methods for measuring voltage during radiofrequency (RF) ablation (RFA) necessitate turning off the ablation catheter. If voltage could be accurately read without signal attenuation during RFA, turning off the catheter would be unnecessary, allowing continuous ablation. We evaluated the accuracy of the Thermocool SMARTTOUCH catheter for measuring voltage while RF traverses the catheter. Methods and Results: We studied 26 patients undergoing RFA for arrhythmias. A 7.5F SMARTTOUCH catheter was used for sensing voltage and performing RFA. Data were collected from the Carto-3 3-dimensional mapping system. Voltages were measured during ablation (RF-ON) and immediately before or after ablation (RF-OFF). In evaluating the accuracy of RF-ON measurements, we utilized the RF-OFF measure as the gold standard. We measured 465 voltage signals. The median values were 0.2900 and 0.3100 for RF-ON and RF-OFF, respectively. Wilcoxon signed rank testing showed no significant difference in these values (P = 0.608). The intraclass correlation coefficient (ICC) was 0.96, indicating that voltage measurements were similarly accurate during RF-OFF versus RF-ON. Five patients had baseline atrial fibrillation (AF), for whom 82 ablation points were measured; 383 additional ablation points were measured for the remaining patients. The voltages measured during RF-ON versus RF-OFF were similar in the presence of AF (P = 0.800) versus non-AF rhythm (P = 0.456) (ICC, 0.96 for both). Conclusion: Voltage signal measurement was similarly accurate during RF-ON versus RF-OFF independent of baseline rhythm. Physicians should consider not turning off the SMARTTOUCH ablation catheter when measuring voltage during RFA. [ABSTRACT FROM AUTHOR]

Background Cryoballoon ablation of pulmonary veins (PVs) is widely used to treat atrial fibrillation (AF). Successful ablation requires occluding the PVs by cryoballoon. Angiography is a standard method of assessing PV occlusion. To decrease contrast doses and overcome potential contraindications (e.g., allergy to contrast, renal disease), alternative methods have been tested, including intracardiac echocardiography, transesophageal echocardiography-color flow Doppler, and distal cryoballoon pressure monitoring. Objective We evaluated pressure monitoring's accuracy in detecting PV occlusion during cryoballoon ablation. Methods We studied 72 PVs in 18 nonconsecutive patients (mean age 68 ± 8 years; 13 male) who underwent cryoballoon ablation for paroxysmal AF. In 67 PVs, we documented the point at which the recorded pressure waveform at the distal tip of the inflated cryoballoon transformed from a left atrial into a pulmonary arterial pressure waveform. PV occlusion was confirmed by concurrent PV angiography through the distal balloon channel. Occlusion was rated on a I-IV scale in which I indicated poor occlusion with major leakage and IV indicated complete occlusion without leakage. Results In 43 of 67 PVs (64%), the change in the pressure waveform from left atrial to pulmonary arterial was associated with complete PV occlusion (grade IV), confirmed by angiography. In the other 24 PVs, complete occlusion was achieved by further movement of the cryoballoon under intracardiac echocardiographic guidance and angiographic confirmation. All 67 PVs were electrically isolated with cryoballoon. Conclusions The change in pressure waveforms at the distal tip of inflated cryoballoon is not a reliable predictor of complete PV occlusion during cryoballoon ablation. [ABSTRACT FROM AUTHOR]

Permanent junctional reciprocating tachycardia, or atrioventricular reentrant tachycardia utilizing a slowly conducting posteroseptal accessory pathway, is a rare form of reentrant supraventricular tachycardia in children and adults. The characteristic features of this narrow complex tachycardia are a long RP interval and inverted P waves in the inferior leads. This form of accessory-pathway-mediated tachycardia, which is usually incessant, can lead to a tachycardia-induced cardiomyopathy and congestive heart failure if left untreated. Radiofrequency ablation of the accessory pathway in permanent junctional reciprocating tachycardia is the definitive treatment in these patients, and in many instances the effects of prolonged tachycardia on ventricular function are reversible after successful ablation. We present an illustrative case. [ABSTRACT FROM AUTHOR]

Introduction: Assessment of ventricular activation pattern is critical to the successful ablation of ventricular tachycardia (VT). We have previously shown that the global atrial activation pattern during tachycardia can be rapidly and accurately assessed by calculating the postpacing interval variability (PPIV); PPIV was minimal in circuitous tachycardias and highly variable in centrifugal tachycardias. In the present study, we use the PPIV to determine the ventricular global activation pattern during VT. Methods: Patients with mappable VT were included. We defined global ventricular activation as either centrifugal (arising from a focus with radial expansion) or circuitous (gross macro-reentrant circuit), based on the findings of electroanatomic mapping. PPIV was calculated as the difference in postpacing interval with right ventricular apical overdrive pacing during tachycardia at cycle lengths (CL) 10 ms and 30-ms shorter than tachycardia, regardless of the origin of the tachycardia. We studied 20 patients with 23 VTs (11 centrifugal, mean CL 390 ± 36.1 ms; 12 circuitous, mean CL 418 ± 75.7 ms). Results: The mean PPIV was 45 ± 16 ms for patients with centrifugal VT and 6.7 ± 4.1 ms for patients with circuitous VT. Rank sum analysis of PPIV showed a significant difference between the two groups (P < 0.05). Conclusions: Our data suggest that the global ventricular activation pattern during VT can be rapidly and accurately defined by assessing the PPIV. This technique allows for a rapid confirmation of the tachycardia activation and significantly facilitates mapping and ablation. (PACE 2010; 33:129–134) [ABSTRACT FROM AUTHOR]