Incidence and location of focal atrial fibrillation triggers in patients undergoing repeat pulmonary vein isolation: implications for ablation strategies

INTRODUCTION: The etiology of atrial fibrillation (AF) recurrences after pulmonary vein (PV) isolation is not well described. The aim of this study was to examine the reason for recurrent AF in patients undergoing a repeat attempt at AF trigger ablation. METHODS AND RESULTS: Patients with recurrent AF more than 1 month after ablation returned for repeat mapping and ablation. A circular mapping catheter was advanced to each previously targeted PV ostium to determine if the PV was still electrically isolated. Ectopy then was provoked with isoproterenol (up to 20 microg/min), burst pacing, and pacing into AF followed by cardioversion. The location of ectopy triggering atrial premature depolarizations (APDs) or AF was noted. Of 226 patients who underwent ablation of AF triggers, 34 (8 women and 26 men; age 56 +/- 10 years) with recurrent AF returned for a repeat procedure 207 +/- 183 days after the first procedure. There were 84 previously completely isolated PVs in these 34 patients. Thirty-three (39%) of 84 previously isolated PVs were still completely isolated at the time of the second procedure. Fifty-one PVs (61%) had evidence of recovered PV potentials. Fifty triggers of APDs and AF (n = 30) or APDs only (n = 20) were identified in these 34 patients. The majority of triggers [27/50 (54%)] originated from previously targeted PVs. Sixteen triggers [16/50 (32%)] originated from previously nontargeted PVs. CONCLUSION: The majority of AF recurrences originate from previously isolated PVs. One third of recurrent triggers originated from PVs that were not targeted during the initial ablation session. Although empiric isolation of all PVs may reduce recurrences, strategies to ensure ostial PV isolation and to prevent recurrent PV conduction after ablation should have the greatest impact on reducing AF recurrence.     

Transcardiac pericardiocentesis: an emergency life-saving technique for cardiac tamponade

Life-threatening cardiac tamponade is one of the most serious complications of catheter-based cardiac procedures. Although most cases can be effectively treated by percutaneous pericardiocentesis, urgent surgical drainage is required in unsuccessful cases. Rarely, in collapsed patients, the delay for surgery, however minimal, may be fatal. We describe a technique whereby life-saving pericardial drainage was rapidly achieved via a novel transcardiac approach, using the transseptal puncture kit, after failure of conventional pericardiocentesis in a patient with procedure-related acute tamponade who rapidly deteriorated and developed cardiorespiratory arrest within a few minutes. Although surgical repair for the perforation had to be performed subsequently, the patient survived without sequelae. This transcardiac approach may be an important and potentially life-saving adjunctive technique after failure of conventional pericardiocentesis in rapidly deteriorating or extremely unstable patients.     

Identification of pulmonary vein potentials by differential site atrial pacing in patients with paroxysmal atrial fibrillation: enhanced detection by pulmonary vein pacing

INTRODUCTION: Pulmonary vein (PV) isolation may cure paroxysmal atrial fibrillation (PAF); however, identification of PV potentials may be difficult in sinus rhythm. Studies have suggested that atrial pacing may improve the identification of PV potentials. METHODS AND RESULTS: In 25 consecutive patients who underwent PV isolation for PAF, the results of pacing from the distal PV, distal and proximal coronary sinus, and high right atrium compared to sinus rhythm were analyzed to determine the most effective pacing site for identification of PV potentials. The percentage of confirmed PV potentials and the longest interval between atrial and PV potentials in each PV were compared during differential site pacing and sinus rhythm. PV potentials were confirmed in 63 (82%) of 77 PVs that could be mapped during the complete pacing protocol and during sinus rhythm. Distal PV pacing identified significantly more PV potentials (left upper pulmonary vein [LUPV] 100%, left lower pulmonary vein [LLPV] 84%, right upper pulmonary vein [RUPV] 80%, right lower pulmonary vein [RLPV] 53%) compared to other pacing sites and sinus rhythm. Among atrial pacing sites, those ipsilateral to the PV being mapped were the most effective for identifying PV potentials. The intervals between atrial and PV potentials were significantly longer during distal PV pacing than pacing at other sites (LUPV 81.6 +/- 26.2 ms, LLPV 61.4 +/- 26.1 ms, RUPV 59.7 +/- 33.2 ms, RLPV 39.7 +/- 26.7 ms). CONCLUSION: (1) Distal PV pacing was most effective for identifying PV potentials. (2) The interval between atrial and PV potentials was longest during distal PV pacing.     

Delineation of intra-atrial reentrant tachycardia circuits after mustard operation for transposition of the great arteries using biatrial electroanatomic mapping and entrainment mapping

INTRODUCTION: Intra-atrial reentrant tachycardia (IART) circuits after Mustard operation remain incompletely understood due to the complex atrial anatomy after extensive surgical procedures. The aim of this study was to delineate IART circuits and their relations to the individual anatomic boundaries in Mustard patients. METHODS AND RESULTS: Twelve patients (10 men and 2 women; age 29 +/- 4.6 years) with atrial tachyarrhythmias after Mustard operation were included in this study. During 14 IARTs and 2 focal atrial tachycardias, electroanatomic mapping and entrainment mapping were performed in both the systemic venous atrium and the pulmonary venous atrium. The latter was accessed via a retrograde transaortic approach. Thirteen IARTs used a single-loop reentrant circuit, and 1 IART used a dual-loop reentrant circuit. Ten (77%) of 13 single-loop reentrant circuits used the tricuspid annulus (TA) as their central barrier. The remaining 3 IARTs rotated around the inferior vena cava (IVC) (n = 2) or ostium of the right upper pulmonary vein (n = 1). In 6 (60%) of the 10 peritricuspid IARTs, both pulmonary venous atrium and systemic venous atrium components of the mid-portion of the TA-IVC isthmus were demonstrated to be part of the reentry. Overall, 12 (86%) of 14 IARTs in 10 patients were successfully ablated by bridging two barriers that constrained the reentrant circuit. Eight (80%) of 10 peritricuspid circuits were abolished by linear ablation connecting the TA to the IVC (n = 4), incisional scar (n = 2), patch (n = 1), and atriotomy (n = 1). CONCLUSIONS: In Mustard patients, the TA serves as the most frequent central barrier of IART. Biatrial electroanatomic mapping combined with entrainment mapping facilitates delineation of IART circuits in relation to their anatomic barriers and enables the design of individual ablation strategies to achieve high success.     

Atrial Fibrillation: What are the Targets for Intervention?

Atrial fibrillation (AF) is a difficult and growing problem in the population. While medical therapy controls symptoms in many patients, a proportion of individuals with this common arrhythmia cannot be optimally managed with drugs alone. However, truly curative therapy for AF has always been one of the holy grails of electrophysiology. The surgical maze procedure was the first to offer permanent maintenance of sinus rhythm in patients with AF but subjected the patient to open heart surgery; a catheter-based translation of the maze procedure served as proof of concept that a catheterization technique could be used to treat AF. Subsequent experience has narrowed the electrophysiologist's attention to ablation of triggers of AF, most often residing in the pulmonary veins, rather than requiring more extensive ablation lines to control the arrhythmia. The following discussion deals with the development and current status of techniques for catheter ablation of atrial fibrillation, focusing on determination of appropriate target sites for ablation.     

Decremental Pulmonary Venous Pulse Propagation: Impact for Catheter Ablation in Focal Atrial Fibrillation

Background: Electrical isolation of pulmonary veins (PV's) is crucial to achieve success in catheter ablation for trigger elimination in focal atrial fibrillation (AF). To guide ostial PV radiofrequency (RF) delivery, it is necessary to identify the electrical breakthrough (EBT) between PV and left atrium. For this purpose, coronary sinus (CS) fixed rate pacing is commonly used. This study evaluated, whether CS extrastimulus pacing is superior in identifying the EBT area as compared to fixed rate pacing. Methods: In 9 patients (51 ± 10 years) undergoing a left sided electrophysiological study for AF ablation, 25 PV's (10 right and 15 left-sided PV's) were mapped using a 4 French fixed-wire catheter with eight 6 mm coiled Platinum electrodes in a distal looped configuration (Revelation Helix, Cardima Inc.). For mapping and ablation the electrode loop was positioned in the PV ostium rectangular to the longitudinal PV axis. EBT area was identified as those electrodes indicating the earliest PV signals during CS pacing. We measured number of EBT electrodes and time between EBT and the latest activated bipoles at the electrode loop during fixed rate and extrastimulus pacing. The reduction of two or more EBT electrodes was defined as a significant benefit in EBT identification. Results: In 22 of 25 PV's mapped PV potentials could be observed. Performing fixed rate pacing the EBT area was identified in a mean of 4.2 ± 1 electrodes, whereas using extrastimulus pacing, EBT area could be significantly reduced to 2.3 ± 0.8 electrodes. The time between EBT and latest electrode activated increased from 14 ± 7 ms to 22 ± 10 ms indicating an intrapulmonary conduction delay during extrastimulus pacing. In 13 of 22 PV's mapped (59%), extrastimulus pacing was beneficial in the identification of the EBT, as the primary target for RF delivery. Conclusions: CS extrastimulus pacing induces intra-PV decremental conduction properties allowing one to identify a more localised and smaller EBT area as the primary target for RF delivery. Performing PV ablation to treat focal AF, extrastimulus maneouvers allow to unmask the true EBT and thus may help to limit intrapulmonary RF delivery.     

Laser assisted delivery of topical anesthesia for intramuscular needle insertion in adults

BACKGROUND AND OBJECTIVES: Currently there is no safe, effective, and rapid means to eliminate the pain associated with a needle insertion through the skin. It is hypothesized that ablation of the stratum corneum layer using a low energy Erbium(Er):YAG laser would allow rapid local anesthesia from a lidocaine product. STUDY DESIGN/MATERIALS AND METHODS: Eighty volunteers participated in a placebo-controlled, double blind, cross-over study employing the Norwood-Abbey (Chelsea Heights, Victoria, Australia) laser anesthesia device (LAD) and two lidocaine preparations. Upper-arm skin ablation was followed by a 5-minute application of study treatment. Pain scores were registered immediately following a needle insertion. RESULTS: Comparing the combined lidocaine preparations to placebo, there was a statistically significant reduction in pain when the LAD was employed (P < 0.001). The median pain reduction for lidocaine was 51.3% (95% CI = [40.9, 76.1]). CONCLUSIONS: Use of the low energy Er:YAG LAD device in combination with a 5-minute application of lidocaine significantly reduced the pain associated with a needle insertion.     

超声引导经皮微波治疗原发性肝癌远期疗效评价

目的　评价经皮穿刺微波凝固治疗 (PMCT)原发性肝癌 (HCC)的远期疗效。方法　在超声引导下对 177例HCC患者共 2 6 5个肿瘤灶进行PMCT ,病灶最大直径 1.5～ 8.7cm ,平均4.12± 1.89cm。随访 5～ 74个月 ,定期复查影像 (彩超、CT、MRI)及血清AFP ,184个结节再次穿刺活检。结果　治疗后超声检查显示 ,92 .0 % (2 0 7/ 2 2 5 )的病灶血流消失 ,88.5 % (138/ 15 6 )的病灶增强CT无强化 ,88.9% (32 / 36 )的病灶增强MRI无强化。 184个结节治疗后再活检 ,92 .4% (170 / 184)完全坏死。 6例患者PMCT后外科切除病灶 ,病理显示肿瘤完全坏死 5例 ,大部分坏死 1例。全组 1～ 5年累计生存率分别为 90 .1%、76 .9%、6 8.3%、6 4.2 %和 5 7.8% ,高分化及中分化者的生存曲线均明显好于低分化者 (P <0 .0 5 ) ,中分化与高分化者之间无统计学差异。全组 1～ 5年累计新生病灶率分别为2 6 .1%、37.8%、43.5 %、48.6 %和 5 8.9%。全组无严重并发症。结论　PMCT治疗HCC安全有效 ,可使直径 <5cm的肿块一次原位灭活 ,患者的 5年生存率较高。     

Radiofrequency ablation of primary and metastatic hepatic malignancies

The majority of patients with primary of metastatic hepatic tumors are not candidates for resection, because of tumor size, location near major intrahepatic blood vessels precluding a margin-negative resection, multifocality, or inadequate hepatic function related to coexistent cirrhosis. Radiofrequency ablation (RFA) is an evolving technology being used to treat patients with unresectable primary and metastatic hepatic cancers. RFA produces coagulative necrosis of the tumor through local tissue heating. Liver tumors are treated percutaneously, laparoscopioally, or during laparotomy, using ultrasonography to identify tumors and to guide placement of the RFA needle electrode. For tumors smaller than 2.0 cm in diameter, one or two deployments of the monopolar multiple-array needle electrode are sufficient to produce complete coagulative necrosis of the tumor. However, with increasing size of the tumor, there is a concomitant increase in the number of deployments of the needle electrode and the overall time necessary to produce complete coagulative necrosis of the tumor. In general, RFA is a safe, well-tolerated, effective treatment for unresectable hepatic malignancies less than 6.0 cm in diameter. Effective treatment of larger tumors awaits the development of more powerful, larger array monopolar and bipolar RFA technologies. Received: January 7, 2002     

Evaluation of Radiofrequency Ablation as an Alternative for the Treatment of Brain Tumor in Rabbits

Radiofrequency ablation (RFA) has emerged recently as a promising therapy for extracranial malignancies. This experiment was conducted to explore the potential of RFA for the treatment of brain tumor in a rabbit model with imaging–histological assessment.Eighteen rabbits with intracranially implanted VX2 tumors of 0.9 ± 0.2cm in diameter were divided into two groups. Group A (n=12) was treated with a cooled-tip RFA technique at 30watts for 30–60s. Group B (n=6) received sham operation. The therapeutic efficacy was evaluated by comparing survival rate, magnetic resonance imaging (MRI) and histological findings.All animals in Group B died within one month after tumor implantation (19 ± 2.6 days). Tumor eradication was achieved in 6/12 rabbits (50.0%) in Group A, of which three rabbits survived longer than three months, another three rabbits were found free of viable tumor when sacrificed. Five rabbits suffered from local tumor relapse. One rabbit developed intracranial metastasis to the brain stem despite a complete ablation of the original tumor. Three-month survival rate of RFA treated rabbits was significantly higher (p < 0.05) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of three characteristic concentric zones, which corresponded to central coagulative tissues (Zone A), peripheral hemorrhagic rim (Zone B) and interstitial edema (Zone C) on histology.This study suggests that RFA may become a promising alternative therapy for the treatment of brain tumor. The recognized characters of thermal lesion on MRI and histology may prove valuable in delimitating the ablation range and understanding the biological response of the RFA.