下腔静脉、三尖瓣环峡部的射频消融治疗心房朴动

目的：报道以下腔静脉、三尖瓣环峡部双向传导阻滞作为终点的心房扑动射顿消融方法，观察该终点对长期疔效的作用。方法；对5例Ⅰ型心房扑动患者的下腔静脉、三尖瓣环峡部进行射频消融。根据右房下侧壁和冠状静脉窦口起搏的右房激动顺序和传导时间变化、评竹蚨部传导阻滞。术后门诊随访观察。结果：5例患者分别于心房扑动(2例)和赛性心律(3例)时接受射频消融治疗，消融后峡部均发生双向传导阻滞。右房下侧壁和冠状静脉赛口起搏的右房激动顺序分别呈顺时针和逆时针单一方向，右房传导时间分别延长82和78ms。随访4个月无一例复发。结论：峡部双向传导阻滞是射频消融心房扑动成功的可靠标志在赛性心律下，亦可对Ⅰ型心房扑动患者进行消融。     

标测指导下点消融隔离三尖瓣环-下腔静脉峡部

目的自三尖瓣环至下腔静脉口线状消融隔离下腔静脉-三尖瓣环峡部是根治大折返环性心房扑动(简称房扑)的标准方法,但是这种方法消融点数多、消融径线盲目.标测指导下点消融隔离下腔静脉-三尖瓣环峡部无系统报告,本研究介绍采用这种方法隔离下腔静脉-三尖瓣环峡部的结果.     

下腔静脉至三尖瓣环连线射频消融治疗心房扑动

报道所完成下腔静脉至三尖瓣环射频消蚀治疗心房扑动7例。均经电生理检查证实为典型房扑，发作时心房率240～320次／分。7例中6树成功；1例失败，为Ebstein畸形伴有巨大右心房者。7例均采用消蚀下腔静脉至三尖瓣环连线的方法，消蚀中用Swartz鞘作支撑，导管在鞘内拖拉，直至消蚀线完成。本研究提示下腔静脉至三尖瓣环线性射频消蚀术是心房扑动治疗的安全有效手段。     

P波形态改变和消融部位双电位与下腔静脉-三尖瓣环峡部完全性阻滞

目的 探讨下腔静脉一三尖瓣环峡部(简称峡部)完全性双向阻滞的心电图和电生理表现。方法对18倒心房扑动患者的峡部进行线性射频消融，峡部发生完全性阻滞后．起搏刺激冠状静脉窦口和右房下侧壁，观察分析I导联P波形态和消融部位双电位。结果18倒患者均消融成功并发生蛱部完全性双向阻滞，并且I导联P波呈负正双向；对12例患者标测消融部位，均记录有特征性双电位，其敏感性为100％。结论心电图I导联P波形态改变和消融部位特征性双电位是判定蛱部完全性阻滞的可靠标志。     

第62课 下腔静脉三尖瓣环峡部消融中心房扑动从逆钟向急转顺钟向——机制如何?

<正>下腔静脉三尖瓣环峡部依赖的心房扑动导管消融已成为一种经常实施的手术,成功率高,是巨折返心律失常的原型。虽然导管消融峡部依赖的心房扑动已成为常规手术,但电生理实验中的不寻常表现并非少见。我们提供这一病例以揭示折返性心律失常和心房扑动的某些电生理原理。病例介绍69岁女性,因心房扑动拟行消融治疗而就诊,既往有快速房性心律失常所致左心室收缩功能正常的充血性心力衰     

典型心房扑动下腔静脉-三尖瓣环峡部电传导特性

目的比较典型心房扑动(房扑)与无房扑患者，下腔静脉-三尖瓣(TV—IVC)峡部的电传导特性。方法 12例同期来本院作射频消融的患者，A组6倒为频繁发作的典型房扑，B组6例为无房扑史的室上性心动过速(室上速)。观寨右房下侧壁(H1-2)和冠状窦口(CS9-10)以周期为600，500，400，300ms起搏时以及房扑和室上速时，TV—IVC峡部传导时间变化。基本刺激周期500ms时，分别测定峡部内、外侧局部心房不应期。结果 ①H1-2起搏时，A组蛱部传导时间较B组平均延长20.3%±11.6%(3.9％～28．9%，但P＞0．05)。CS9-10起搏时，A组峡部传导时间较B组传导时间平均延长27.1％±10.5%（12．5％～35.8％．但P>0．05)。②房扑时峡部传导时间133±6．6ms。室上速峡部传导时间61．1±12．7ms．两组(P<0．05)。③A、B组峡部局部心房有效不应期(ERP)差异无显著性。结论下腔静脉-三尖瓣峡部是折返环的一部分。但窦性心律时蛱部无显著传导延迟。房扑功能慢传导区不一定局限于该部位。     

下腔静脉-三尖瓣环连线射频消融治疗Ⅰ型心房扑动

目的 观察连线射频消融对治疗心房扑动的效果。方法 对4例Ⅰ型心房扑动(房扑)患者用解剖标志法从下腔静脉口(IVC)～三尖瓣环(TA)进行多次连线消融、结果4例均成功终止房扑,平均放电6.5±2.8次,每靶点平均消融1.86min,无手术相关井发症发生。随访2～5个月无复发。结论 采用IVC～TA连线射频消融可有效地阻断房扑,其远期效果有待观察。     

CARTO指导下三尖瓣环峡部解剖特征对线性消融的影响

目的探讨CARTO系统指导下三尖瓣环峡部(CTI)的解剖学特点及其对线性消融的影响。方法接受CTI线性消融的患者,其中典型心房扑动5例、阵发性心房颤动(简称房颤)10例及持续性房颤40例。利用CARTO系统对三尖瓣峡部长度、跨度及最深深度进行测量并根据深度分为囊袋型、凹陷型和平坦型。根据CTI长度将患者分为两组,长组≥35 mm,短组<35 mm。记录CTI消融成功所需时间,同时收集相关临床资料。结果不同类型峡部的长度、跨度、深度及消融所需时间分别为:囊袋型23例(45.5±7.5 mm,38.0±7.4 mm,-9.5±2.8 mm,1707±615 s),凹陷型10例(42.7±9.0 mm,37.2±6.7 mm,-4.2±0.8 mm,1 327±832 s),平坦型22例(36.1±8.9 mm,34.3±8.0 mm,-1.0±3.1 mm,927±404 s)。囊袋型CTI长度、消融时间长于平坦型,囊袋型CTI深度均较平坦型和囊袋型为深(P<0.05)。消融时间与深度正相关(r=0.505,P<0.001)。长组较短组所需消融时间长(1485±681 s vs 803±305 s,P<0.001)。长组以囊袋型为主(48.8%),短组以平坦型为主(78.6%)。结论 CTI线性消融时间与其最深深度相关,峡部越深则消融越费时,囊袋型消融所需时间最多。若CTI长度≥35 mm(更常见于囊袋型CTI),其消融时间则显著延长。     

下腔静脉三尖瓣环峡部消融中心房扑动从逆钟向急转顺钟向——机制如何？

下腔静脉三尖瓣环峡部依赖的心房扑动导管消融已成为一种经常实施的手术,成功率高,是巨折返心律失常的原型。虽然导管消融峡部依赖的心房扑动已成为常规手术,但电生理实验中的不寻常表现并非少见。我们提供这一病例以揭示折返性心律失常和心房扑动的某些电生理原理。     

先天性心脏病术后下腔静脉口-三尖瓣环峡部依赖性心房扑动的导管消融疗效分析

目的:报道先天性心脏病术后下腔静脉口-三尖瓣环峡部依赖性心房扑动的相对发生率及导管消融的疗效和安全性。方法:选择2002年1月-2006年4月在我院因先天性心脏病术后心房内折返性心动过速行射频消融的40例患者,应用常规电生理标测方法或三维标测方法(Carto和Ensite)指导导管消融,观察下腔静脉口-三尖瓣环峡部心房扑动相对发生率及其导管消融结果。结果:40例患者共诱发出50种房性心动过速,具有典型下腔静脉口-三尖瓣环峡部依赖性心房扑动心电图表现,且成功靶点在下腔静脉口和三尖瓣环峡部者31种(31／50,62．0％)。另外19种(19／50,38．0％)房性心动过速临床心电图表现与典型心房扑动不同,表现为P’波,其中11种(11／50,22．0％)成功靶点在右心房游离壁疤痕-下腔静脉峡部,瘢痕-上腔静脉峡部者2种,瘢痕与瘢痕之间峡部者2种;在瘢痕和三尖瓣环之间2种。房间隔补片和上腔静脉之间、房间隔补片和三尖瓣环之间各消融成功1种。40例患者射频消融成功,无并发症。随访1例患者心动过速复发,二次消融成功;1例患者出现持续性心房颤动伴RR长间歇,植入永久性起搏器。结论:先天性心脏病术后心房内折返性心动过速常常为下腔静脉口-三尖瓣环峡部心房扑动,导管消融具有较高的疗效和安全性。     

Incremental Pacing for the Diagnosis of Complete Cavotricuspid Isthmus Block During Radiofrequency Ablation of Atrial Flutter

Incremental Pacing for the Diagnosis of Cavotricuspid Isthmus Block.   Background: Complete conduction block of the cavotricuspid isthmus (CTI) reduces atrial flutter recurrences after ablation. Incremental rapid pacing may distinguish slow conduction from complete CTI conduction block.
Methods and Results: Fifty-two patients (67 ± 9 years) undergoing 55 CTI ablation procedures were included. With ablation, double potentials (DPs) separated by an isoelectric line of ≥30 ms were obtained. Incremental atrial pacing (600–250 ms) was performed from coronary sinus (CS) and low lateral right atrium (LLRA). A <20 ms increase in the DPs distance during incremental pacing was indexed as complete CTI block. In 8 patients, an initial <20 ms DPs distance increase was noted; direct complete isthmus block was suggested and no additional ablation performed. In the remaining, the CTI line was remapped for conduction gaps and additional radiofrequency energy pulses applied. Complete block, as indexed by incremental pacing, occurred in 46 of 55 procedures, with one flutter recurrence (follow-up 8 ± 2 months): DPs interval variation of 116 ± 20 to 123 ± 20 ms (CS), P = 0.21; and 122 ± 25 to 135 ± 35 ms (LLRA), P = 0.17. The remaining 9 patients (persistent rate-dependent DPs increase) presented 3 flutter recurrences, P = 0.01: DP distance from 127 ± 15 to 161 ± 18 ms (CS), P < 0.001; and 114 ± 24 to 142 ± 10 ms (LLRA), P = 0.007.
Conclusion: Incremental pacing distinguishes complete CTI block from persistent conduction. Such identification, accompanied by additional ablation to achieve block, should minimize flutter recurrences after ablative therapy. (J Cardiovasc Electrophysiol, Vol. 21, pp. 33–39, January 2010)     

Differential Pacing for Distinguishing Slow Conduction from Complete Conduction Block of the Tricuspid-Inferior Vena Cava Isthmus after Radiofrequency Ablation for Atrial Flutter—Role of Transverse Conduction through the Crista Terminalis

Background: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL).Aim: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line.Methods: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge–tricuspid valve isthmus for typical AFL. Activation patterns along the tricuspid annulus (TA) suggested incomplete CB across the isthmus. In these patients, atrial pacing was performed from the low posteroseptal (PS) and anteroseptal (AS) right atrium (RA) while the ablation catheter was placed at the ablation line where double potentials (DPs) could be recorded. The pattern of activation of the RA free wall was assessed by a 20-pole catheter positioned along the CT during pacing from the coronary sinus (CS) ostium (CSos) and low lateral RA (LLRA).Results: Faster transverse conduction across the CT resulted in simultaneous or earlier activation of the distal halo electrodes than of the more proximal electrodes, suggesting incomplete conduction block across the isthmus. CB (13) and SC (1) were detected as changes in the activation times of the first and second components of DPs (DP1, DP2) during PS RA pacing and AS RA. Similar changes in the activation times DP1 and DP2 during AS RA pacing as compared to PS RA reflected SC through the isthmus, whereas increased DP1 activation time and decreased of DP2 activation time reflected complete conduction block across the isthmus.Conclusions: Transverse conduction across the CT influences the sequence of activation along the TA after isthmus ablation. Differential pacing can distinguish SC from complete conduction block across the ablation line in the isthmus.     

A New and Simple Method for Distinguishing Complete from Incomplete Block Through the Cavotricuspid Isthmus

Background: A complete line of block (CLOB) in the cavotricuspid isthmus (CTI) is the endpoint of typical atrial flutter ablation. Before CTI block is obtained, a progressive CTI conduction delay due to an incomplete line of block (InLOB) can be difficult to distinguish from CLOB. The purpose of this study was to assess a new simple approach based on the changes in atrio-ventricular (AV) conduction delays during septal and lateral right atrial pacing, to distinguish a CLOB from an InLOB during typical atrial flutter (AFL) ablation. Methods and Results: Forty patients who presented an InLOB before a CLOB, and a stable (AV) conduction delay at 600 ms cycle length pacing (when in sinus rhythm), during AFL ablation were included in this study. A 24-pole mapping catheter was positioned so that 2 adjacent dipoles bracketed the targeted CTI line of block (LOB), with proximal dipoles lateral to the LOB and distal dipoles in the coronary sinus. Two pacing sites were lateral (position L1 and L2) and one was septal (position S) to the LOB, with locations L1 and S closest to the LOB. During L1, L2 and S site pacing, the delay between the pacing artefact and the peak of the R wave in a surface ECG (lead II) was measured. We measured the following conduction delays (mean ± SD in ms), during InLOB versus CLOB: (L1 to R) 320.5 ± 68.0 versus 367.0 ± 62.0, p = 0.001; (L2 to R) 333.0 ± 59.0 versus 338.0 ± 62.0, p = 0.663, (S to R) 259.4 ± 51.5 versus 247.1 ± 55.5, p = 0.987. We calculated the following data during an InLOB versus a CLOB: (L1R–L2R) − 12.3 ± 7 versus 20.2 ± 12.7, p = 0.001; (L1R–SR) 51.1 ± 21.5 versus 120.1 ± 16.6, p < 0.05. The sensitivity, specificity, positive and negative predictive values for CLOB with (L1R-SR > 94 ms) and with (L1R-L2R > 0 ms) were respectively; 100%, 98%, 98% and 100%. Conclusions: This study establishes that lateral versus septal right atrial pacing sites combined with the measure of AV conduction delay on a surface ECG can be useful to distinguish a CLOB from an InLOB during AFL ablation.     

The LETR-Principle: A Novel Method to Assess Electrode-Tissue Contact in Radiofrequency Ablation

Minimal Power RF Application. Introduction: Stable electrode-tissue contact is crucial for successful radiofrequency ablation of cardiac tachyarrhythmias. In this in vitro study, a custom-made radiofrequency generator was used to evaluate the correlation between tip temperature response to a minimal radiofrequency power delivery (Low Energy Temperature Response: LETR-Principle) and electrode-tissue contact as well as lesion size.
Methods and Results : A battery-powered radiofrequency generator (LETR-Box, 500 kHz, 0.1 to 0.3 W) could measure the temperature increase at the tip electrode with 0.01°C accuracy. The device was tested in vitro using isolated porcine ventricular tissue. For various electrode-tissue settings (i.e., 0 to 0.89 N contact force), the temperature increase (δT) due to 0.1-W power delivery for 10 seconds was recorded. Subsequently, for the same electrode-tissue contact, a temperature-controlled radiofrequency ablation was performed (70°C target temperature. 50-W maximum output, 30 sec). Thereafter, the lesion size was measured histologically. To prove the safety of the applied LETR-Principle, the tissue was inspected microscopically after continuous radiofrequency power delivery of 0.3 W for 1 hour with high contact pressure (1.33 N). The delivery of 0.1-W radiofrequency power resulted in an average δT of 0.18° plusmn; 0.13°C. During temperature-controlled radiofrequency ablation, the tip temperature was 59° 8.5°C, resulting in a lesion depth of 4.8 ± 0.6 mm. The correlation coefficient between δT and contact force was 0.97 and 0.81. respectively, for lesion depth. No lesion was microscopically visible after power delivery of 0.3 W for 1 hour with 1.33 N contact pressure.
Conclusion : The LETR-Principle safely indicates electrode-tissue contact and lesion depth under in vitro conditions and can be useful for catheter positioning during radiofrequency ablation procedures.     

Radiofrequency Catheter Ablation for Intra-Atrial Reentrant Tachycardia after Surgery of Atrial Septal Defect: Use of Isopotential Mapping (QMS system) to Demonstrate Bidirectional Complete Block

A 51 year-old Japanese man who had undergone surgical correction of an atrial septal defect at the age of 18 years old was referred to our institute for evaluation of his atrial arrhythmia. The conventional electrophysiological study was combined with a new technique utilizing an isopotential and isochronal mapping system (QMS) to visualize the electrical signals recorded with a 64-electrode basket catheter. Using this system, an intra-atrial reentrant tachycardia (IART) was demonstrated. The isopotential map recorded with the QMS (QMS-isoP) rapidly revealed a clockwise global reentrant circuit in the mid free wall of the right atrium and a narrowest activation isthmus between the lower end of the atriotomy scar and the inferior vena cava (IVC). After confirming entrainment with concealed fusion at the lower end of the atriotomy scar, radiofrequency energy was delivered linearly from this site to the IVC by slowly dragging the catheter. The elimination of the IART was defined by the QMS-isoP which demonstrated bidirectional block during pacing from both sides of the ablated linear lesion. The conventional technique of entrainment with concealed fusion combined with the QMS-isoP may result in a highly sophisticated method for identifying global reentrant circuits and for defining bidirectional block after eliminating the IART.     

射频消融室性早搏治疗特发性心室颤动(附一例报道)

报道一例射频消融室性早搏 (简称室早 )治疗特发性心室颤动 (简称室颤 )。患者男性 ,2 3岁。 1个月内反复发作晕厥 4次 ,体表心电图和动态心电图证实频发室早。心室晚电位、倾斜试验、超声心动图检查均未发现异常。电生理检查时发作室颤 ,经 30 0J电击转复为窦性心律 ,回放 12导联心电图可见室颤前有频发室早。采用起搏标测 ,于右室游离壁起搏产生与室早 12导联心电图类同的QRS波 ,温控 5 0℃ ,5 0W ,消融 12 0s,室早消失。术后随访3个月 ,患者无晕厥发作。结论 :消融室颤触发物 (室早 )可预防室颤的发作。     

Biventricular stimulation to prevent cardiac desynchronization: rationale, design, and endpoints of the 'Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace)' study.

Despite the deleterious effects of cardiac dyssynchrony and the positive effects of cardiac resynchronization therapy, patients with high-degree atrioventricular block continue to receive desynchronizing right ventricular (RV) pacing systems. Although it is unclear whether the negative effects of RV pacing and left bundle branch block (LBBB) are comparable, and whether they depend on the presence and the degree of structural heart disease, one may hypothesize that RV pacing may have similar effects to LBBB. In the BioPace trial, the long-term effects of RV pacing vs. biventricular pacing will be prospectively compared in 1200 pacemaker patients with high likelihood of mostly paced ventricular events, regardless of whether in sinus rhythm or in atrial fibrillation (AF). After echocardiographic examination of left ventricular (LV) function, patients will be randomly assigned to the implantation of an RV vs. a biventricular pacing system and followed for up to 5 years. Primary study endpoints are survival, quality of life (QoL), and the distance covered in a 6-min hall walk (6-MHW) at 24 months after implantation. Secondary endpoints are QoL and the 6-MHW result at 12 months after implantation, hospitalization rate, LV dimensions, LV ejection fraction, and the development of chronic AF and other adverse events.