心房不同部位拖带法鉴别不典型房室结折返性心动过速和房性心动过速

目的报道一种鉴别不典型房室结折返性心动过速(AVNRT)和起源点邻近Kock三角的房性心动过速(AT)的新方法。方法 22例室上性心动过速患者,在心房不同部位(右房心耳部、冠状静脉窦近端、远端)起搏拖带心动过速,测定起搏后VA间期(最后一个起搏脉冲前传夺获的心室电图到起搏终止后第一心搏的最早心房电图的距离)。计算各部位起搏后VA间期的差别并取差别绝对数的最大值定义为ΔVA间期。结果 13例AVNRT起搏后ΔVA间期5.8±3.6(0～14)ms,9例AT起搏后ΔVA间期62.8±24.2(21～98)ms。ΔVA间期在所有AVNRT均<15 ms,在所有AT均>15 ms,因此起搏后ΔVA间期>15 ms用于诊断AT的灵敏度和特异度均为100%。结论心房不同部位起搏拖带法可用于准确鉴别不典型AVNRT和起源点邻近Kock三角的AT。     

心室起搏拖带对房室结折返性和间隔旁路参与的房室折返性心动过速的鉴别作用

目的　研究心动过速时心室起搏拖带对房室结折返性心动过速 (AVNRT )和间隔旁路参与的顺向型房室折返性心动过速 (间隔旁路ORT)的鉴别意义。方法　 30例AVNRT和 2 5例间隔旁路ORT病人在心动过速发生后 ,采用较心动过速的周长 (TCL)短 10～ 4 0ms的周长行右心室起搏拖带心动过速。测量右心室起搏之前的心室 心房 (VA)间期和TCL。停止起搏后 ,测量最后一次刺激信号至最后起搏拖带的心房激动 (SA)间期 ,以及起搏后间期 (PPI)。结果　所有 30例AVNRT病人的SA -VA间期 >85ms、PPI-TCL >115ms,而 2 5例ORT病人的SA -VA间期 <85ms、PPI-TCL <115ms。结论　PPI TCL和SA VA间期是鉴别AVNRT和间隔旁路ORT的非常可靠的指标 ,具有较高的特异性。     

疑难性的房室及房室结折返性心动过速与房性心动过速快速简捷的鉴别方法

目的探讨简便、快捷鉴别疑难的房室及房室结折返性心动过速与房性心动过速的方法.方法分别对20例间隔旁路(包括4例慢旁路),20例房室结双径路(包括不典型房室结双经路1例)以及11例房速(6例房速,5例房室结双径路慢径路消融术后S1S1心房刺激模拟房速)患者,在心动过速过程中行心室RS2刺激,所有患者心室RS2刺激均能夺获心室并且逆传心房,而且不终止心动过速,观察心室刺激时心房的反应,反应方式分别为V＇-A＇-V-A(V＇S2刺激后心室波,A＇V＇波逆传心房波,V心动过速时室波,A心动过速时房波)或V＇-A＇-A-V.结果20例间隔区房室折返性心动过速的患者,心室RS2刺激的反应方式均为V＇A＇VA,其中16例V＇A＇间期＜A＇-V间期,4例慢旁道V＇A＇间期＞A＇V间期,V-A均较远(＞60ms),V＇A＇间期与VA间期相近.20例房室结折返性心动过速病人行心室RS2刺激的反应方式呈V＇A＇-V-A14例,呈V＇-A＇-A-V6例,1例不典型房室结折返性心动过速患者VA间期130ms,余13例呈V＇-A＇-V-A反应的患者VA均较近(VA＜60ms),6例呈V＇-A＇AV的患者AV较近或者融合(AV＜60ms).6例房速以及5例模拟房速患者心室RS2刺激均呈V＇-A＇-A-V反应,AV均较远(100ms).结论心动过速过程中行RS2心室刺激,是鉴别疑难的阵发性室上性心动过速的快速、简洁而有效的方法.     

间隔附近起源心动过速鉴别诊断一例

35岁女性因室上性心动过速行电生理检查和射频消融。术中诱发宽QRS心动过速,尝试心室超速起搏后变为窄QRS波,起搏后间期－心动过速周长为125 ms。仔细分析可发现两种心动过速周长和VA间期相同,希氏束呈现顺向夺获,校正后的起搏后间期－心动过速周长为75 ms。考虑顺向型房室折返性心动过速,于二尖瓣环左后间隔处消融成功。     

房室结折返性心动过速室房传导的规律

通过窄 QRS心动过速的心电图 RP′间期及心内电图VA间期变化 ,探讨房室结折返性心动过速 (atrioventriculanodal reentrant tachycardia,AVNRT)室房传导的规律性。　　资料和方法　选择对象为经心内电生理检查及射频消融治疗证实为房室结双经路慢 -快型折返性心动过速的 46例患者 ,男性 2 0例 ,女性 2 6例 ,平均年龄 (4 4± 15 )岁。 46例患者 ,窦性心律时心电图无异常 ,心动过速时呈窄 QRS波 ,QRS时限 <0 .11s,伴 1∶ 1的室房激动关系 ,心动过速时记录体表心电图及希氏束 (HBE)及冠状静脉窦近端 (CS9～10 )心内电图来观察 RP′间…     

不典型房室结折返性心动过速与房室折返性心动过速的电生理鉴别

房室结折返性心动过速(AVNRT)与房室折返性心动过速(AVRT)的鉴别有时较困难,尤其是不典型AVNRT与间隔旁道参与的AVRT鉴别,不典型AVNRT在心动过速发生时最早心房激动位于后间隔区域,与后间隔旁道引起的AVRT相似。通常检测房室结双径路的电生理方法仅能鉴别63%的不典型AVNRT。该文介绍了两者的主要电生理鉴别方法,包括希氏束旁起搏、在希氏束不应期给予心室期前程序刺激、心室或希氏束旁起搏后间期与心动过速周长之差(PPI-TCL)和刺激信号至心房波减去室房(SA-VA)间期的区别、校正的心室PPI-TCL和VA间期、心动过速时VA分离现象及TCL行心室起搏时的VA间期与心动过速时的VA间期之差等9种方法。     

隐匿性旁路与房室结折返性心动过速鉴别诊断的临床研究

目的观察经校正的心室起搏拖带起搏后间期（PPI）与心动过速周长（TCL）差值，在隐匿性旁路介导的顺向房室折返性心动过速（O-AVRT）与房室结双径路所致房室结折返性心动过速（AVNRT）鉴别诊断中的价值。方法选择经心内电生理检查和射频消融的65例室上速心动过速患者，窦律时无预激波出现。其中AVNRT37例、O-AVRT28例，以快于心动过速频率5-15次／min的刺激频率进行心动过速拖带，比较校正的心室起搏拖带的PPI与TCL差值等参数在这两组中的差异。结果心内电生理检查发现，28例O-AVRT和37例AVNRT患者，除2例AVNRT患者外均成功拖带，28例O-AVRT患者校正的PPI－TCL差值[（68±20）ms]短于35例AVNRT患者校正的差值[（151±16）ms，P〈0．01]。所有O-AVRT患者校正的PPI-TCL差值均〈110ms，而AVNRT患者的差值均〉110ms。间隔部旁路患者校正的PPI-TCL差值比游离壁旁路患者更短一些。结论经校正的PPI-TCL差值测定是一项快速、有效的鉴别AVNRT和隐匿性O-AVRT的方法，对射频消融具有重要的指导意义；校正的PPI-TCL差值〈110ms对确诊O-AVRT患者能提供更大的判断价值。     

心动过速拖带现象

拖带现象是指心动过速时给予超速起搏刺激,使原有的心动过速频率加速到刺激频率,当刺激停止或刺激频率减慢至原来心动过速频率以下时,即恢复原有心动过速的电生理现象。1977年Waldo等在研究心房扑动时发现了该现象,并命名为拖带现象。拖带现象是折返性心动过速所具有的特征性表现,常见于超速刺激终止心房扑动、心房折返性心动过速、房室结折返性心动过速、房室折返性心动过速和室性心动过速时。     

房性心动过速的射频导管消融术治疗

目的：为治疗房性心动过速（房速）,对8例患者进行了射频导管消融术（RFCA）治疗。方法：采用两根大头消融导管,在房速发作时标测心房最早激动点放电消融。结果：8例房速（包括房速伴心房扑动及房速伴房室结折返性心动过速各1例）RFCA治疗全部成功,无并发症;其中4例在冠状静脉窦口附近、2例在右心房侧壁、2例在右心耳处放电消融成功,成功靶点局部电位（A波）较体表心电图P波平均提前34.23±5.23（22～46）ms。结论：心房激动顺序标测是房速消融的基本方法,AP间期≥30ms的部位可作为试消融靶点;对房速伴其他类型心动过速者可一次消融成功。     

隐匿性拖带时起搏后间期与慢径消融成功靶点的关系

评价应用隐匿性拖带方法对准确靶点消融的有效性及探讨常规慢径靶点部位与房室结折返性心动过速(AVNRT)折返环的关系。可反复诱发的持续性典型AVNRT的患者 34例 ,消融导管在后或中间隔标测到A/V≤ 0 .5处 ,然后诱发心动过速 ,在高位右房 (HRA)和冠状窦口 (CSO)超速起搏产生隐匿性拖带 ,并按常规方法进行慢径消融。比较隐匿性拖带时靶点部位起搏后间期与心动过速周长的差值 (PPI-TCL值 )在成功靶点与不成功靶点区别。结果 :HRA超速起搏发生隐匿性拖带时 ,His束记录部位A波均为逆向夺获。而CSO超速起搏拖带时 ,32例His束记录部位A波为顺向夺获 ,另 2例为逆向夺获。在这 32例中共记录 5 4个靶点 ,成功靶点的PPI-TCL值明显小于不成功靶点 (12 .4± 5 .8msvs 32 .1± 18.6ms,P <0 .0 1)。PPI-TCL值≤ 2 0ms对靶点成功消融的敏感性和特异性分别为 84%、81%。结论 :本研究提示常规慢径消融成功部位作为房室结外的后部延伸组织参与组成AVNRT折返环或距其非常近。在可持续发作和诱发的AVNRT患者中 ,CSO部位起搏拖带顺向心房夺获时 ,靶点部位测出的PPI-TCL值≤ 2 0ms,可作为一种新的慢径路电生理定位消融方法     

The Response of Paroxysmal Supraventricular Tachycardia to Overdrive Atrial and Ventricular Pacing:

Pacing During Supraventricular Tachycardia. Introduction: Standard electrophysiologic techniques generally allow discrimination among mechanisms of paroxysmal Supraventricular tachycardia. The purpose of this study was to determine whether the response of paroxysmal Supraventricular tachycardia to atrial and ventricular overdrive pacing can help determine the tachycardia mechanism. Methods and Results: Fifty-three patients with paroxysmal Supraventricular tachycardia were studied. Twenty-two patients had the typical form of atrioventricular (AV) junctional (nodal) reentry, 18 patients had orthodromic AV reentrant tachycardia, 10 patients had atrial tachycardia, and 3 patients had the atypical form of AV nodal reentrant tachycardia. After paroxysmal Supraventricular tachycardia was induced, 15-beat trains were introduced in the high right atrium and right ventricular apex sequentially with cycle lengths beginning 10 msec shorter than the spontaneous tachycardia cycle length. The pacing cycle length was shortened in successive trains until a cycle of 200 msec was reached or until tachycardia was terminated. Several responses of paroxysmal Supraventricular tachycardia to overdrive pacing were useful in distinguishing atrial tachycardia from other mechanisms of paroxysmal Supraventricular tachycardia. During decremental atrial overdrive pacing, the curve relating the pacing cycle length to the VA interval on the first beat following the cessation of atrial pacing was flat or upsloping in patients with AV junctional reentry or AV reentrant tachycardia, but variable in patients with atrial tachycardia. AV reentry and AV junctional reentry could always be terminated by overdrive ventricular pacing whereas atrial tachycardia was terminated in only one of ten patients (P < 0.001). The curve relting the ventricular pacing cycle length to the VA interval on the first postpacing beat was flat or upsloping in patients with AV junctional reentry and AV reentry, but variable in patients with atrial tachycardia. The typical form of AV junctional reentry could occasionally be distinguished from other forms of paroxysmal Supraventricular tachycardia by the shortening of the AH interval following tachycardia termination during constant rate atrial pacing. Conclusions: Atrial and ventricular overdrive pacing can rapidly and reliably distinguish atrial tachycardia from other mechanisms of paroxysmal Supraventricular tachycardia and occasionally assist in the diagnosis of other tachycardia mechanisms. In particular, the ability to exclude atrial tachycardia as a potential mechanism for paroxysmal Supraventricular tachycardia has important implications for the use of catheter ablation techniques to cure paroxysmal Supraventricular tachycardia.     

The VA relationship after differential atrial overdrive pacing: a novel tool for the diagnosis of atrial tachycardia in the electrophysiologic laboratory

Introduction: Despite recent advances in clinical electrophysiology, diagnosis of atrial tachycardia (AT) originating near Koch's triangle remains challenging. We sought a novel technique for rapid and accurate diagnosis of AT in the electrophysiologic laboratory.
Methods: Sixty-two supraventricular tachycardias including 18 ATs (10 ATs arising from near Koch's triangle), 32 atrioventricular nodal reentrant tachycardias (AVNRTs), and 12 orthodromic reciprocating tachycardias (ORTs) were studied. Overdrive pacing during the tachycardia from different atrial sites was performed, and the maximal difference in the postpacing VA intervals (last captured ventricular electrogram to the earliest atrial electrogram of the initial beat after pacing) among the different pacing sites was calculated (delta-VA interval).
Results: The delta-VA intervals were >14 ms in all AT patients and <14 ms in all AVNRT/ORT patients, and thus, the delta-VA interval was diagnostic for AT with the sensitivity, specificity, and positive and negative predictive values all being 100%. When the diagnostic value of the delta-VA interval and conventional maneuvers were compared for differentiating AT from atypical AVNRT, both a delta-VA interval >14 ms and "atrial-atrial-ventricular" response after overdrive ventricular pacing during the tachycardia were diagnostic. However, the "atrial-atrial-ventricular" response criterion was available in only 52% of the patients because of poor ventriculoatrial conduction.
Conclusions: The delta-VA interval was useful for diagnosing AT irrespective of patient conditions such as ventriculoatrial conduction.     

A novel pacing manoeuvre to diagnose atrial tachycardia

Aims: Currently used diagnostic manoeuvres at the electrophysiologystudy do not always allow for consistent identification of atrialtachycardia (AT), either because of inapplicability of the techniqueor because of low predictive value and specificity. The aimof this study was to determine whether overdrive atrial pacingduring paroxysmal supraventricular tachycardia (SVT) with thesame cycle length from both the high right atrium and the coronarysinus can accurately identify or exclude AT by examining thedifference between the V–A intervals of the first returningbeat of tachycardia between the two pacing sites. Methods and results: Fifty-two patients were included; 24 patients with atrioventricularnodal re-entry tachycardia (AVNRT), 13 patients with atrioventricularre-entry tachycardia (AVRT), and 15 patients with AT. Comparingthe 37 non-AT patients with the 15 AT patients, there was ahighly significant difference between the mean V–A intervaldifference, (delta V–A) 2.1 ± 1.8 ms (range 0–9ms) vs. 79.1 ± 42 (range 22–267 ms) (P < 0.001),respectively. None of the patients in the non-AT group had adelta V–A > 10 ms. In contrast, all 15 patients withAT had a delta V–A interval >10 ms. Thus, the diagnosticaccuracy of the delta V–A interval cut-off of >10 mswas 100%, with a 95% confidence interval of 93.1–100%for AT. In 11 (73%) of the 15 AT patients, the standard ventricularoverdrive pacing manoeuvre was not possible. In 14 of the 15patients (93%) in the AT group, standard atrial overdrive pacingshowed variable V–A intervals, correctly diagnosing AT.In all 52 patients, this measurement was repeated during pacingfrom the other location. In five patients from the AT group,the result of the second attempt was different from the resultof the first attempt. Conclusion: We found that atrial differential pacing during paroxysmal SVTwithout termination of tachycardia and the finding of variablereturning V–A interval was highly sensitive and specificfor the diagnosis of AT. The manoeuvre can be easily performedin all patients with SVT and is highly reproducible. It is auseful adjunct to the currently available ventricular and atrialpacing manoeuvres.     

Significance of pacing cycle lengths in manifest entrainment of orthodromic circus movement tachycardia by ventricular pacing

The physiology of entrainment of orthodromic circus movement tachycardia (CMT) was studied using ventricular pacing during 18 episodes of induced CMT in 7 patients with atrioventricular (AV) accessory pathways. The first paced impulse was delivered as late as possible in the tachycardia cycle (mean 88 +/- 5% of the spontaneous cycle length [CL]). Entrainment was demonstrated by the following criteria: 1:1 retrograde conduction via the accessory pathway; capture of atrial, ventricular and His bundle electrograms at the pacing rate; and resumption of tachycardia at its previous rate after cessation of pacing. The number of ventricular paced impulses ranged from 5 to 14 (mean 8 +/- 3), and entrainment occurred in 2 to 7 paced cycles (mean 4 +/- 2). Orthodromic activation of a major part of the reentry circuit (manifest entrainment) was demonstrated during 9 episodes by the occurrence of His bundle electrogram preceding the first CMT QRS at the time anticipated from the last paced beat. In the 9 other episodes, persistent retrograde His bundle activation and AV nodal penetration by each paced impulse caused a delay (mean 79 +/- 25 ms) in activation of the His bundle preceding the first CMT QRS after the last paced beat. The mean pacing CL achieving manifest entrainment was 92 +/- 3% of the tachycardia CL, compared with 84 +/- 3% for retrograde AV nodal penetration (p less than 0.01). In conclusion, manifest entrainment of orthodromic CMT can be demonstrated by ventricular pacing at very long CLs; shorter CLs may cause CMT termination due to retrograde AV nodal penetration.     

Influence of Ventriculoatrial Timing on Hemodynamics and Symptoms During Supraventricular Tachycardia

Aims: Patients with reentrant supraventricular tachycardia (SVT) are often highly symptomatic and the mechanism of symptoms is not well understood. We hypothesized that variation in ventriculoatrial interval (QRS to P) modulates the left atrial pressure and symptoms during tachycardia.
Methods and Results: Three hundred twenty-six patients awaiting electrophysiological study completed a questionnaire regarding "neck pounding" or "shirt flapping" during tachycardia. Mean left atrial pressure was measured during simulated atrioventricular reentry tachycardia (AVRT) and atrioventricular nodal reentry tachycardia (AVNRT) in 18 patients. Pulmonary venous flow reversal was assessed using transesophageal echocardiography in 12 dogs when pacing at 220 bpm with different VA delays (0 to 250 ms). "Shirt flapping" is present more often during AVNRT than during AVRT (58.6% vs 43.8%, respectively, P < 0.05). Simulated AVNRT is associated with higher left atrial pressure compared with AVRT (19.4 ± 4.8 mmHg vs 13.7 ± 3.9 mmHg, respectively, P < 0.05). In dogs, pulmonary venous flow reversal during atrial systole was observed with significantly decreasing amplitude as VA delays increased: 668 ± 167% at 0 ms; 492 ± 138% at 100 ms; 278 ± 148% at 180/ms; and 134 ± 91% at 220 ms.
Conclusion: " Shirt flapping" and "neck pounding" frequently occur during AVNRT. LA contractions during AV valve closure increase left atrial pressure and may explain differences in certain symptoms between AVNRT and AVRT.     

Overdrive suppression of antegrade conduction over the accessory pathway

In a patient with Wolff-Parkinson-White syndrome whose accessory pathway was primarily capable of bidirectional conduction, antegrade conduction over the accessory pathway was transiently inhibited after rapid atrial or ventricular pacing or after spontaneous termination of atrioventricular reentrant tachycardia. Pacing rate and duration of tachycardia were related to the duration of the suppression of preexcitation, while the coupling interval of the first sinus beat to the last driven or tachycardia beat was irrelevant to the phenomenon. Thus, overdrive suppression of conduction may be the most likely mechanism of this phenomenon.     

Differentiation of atypical atrioventricular node re-entrant tachycardia from orthodromic reciprocating tachycardia using a septal accessory pathway by the response to ventricular pacing

OBJECTIVES: The purpose of this study was to determine whether the response to ventricular pacing during tachycardia is useful for differentiating atypical atrioventricular node re-entrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT) using a septal accessory pathway. BACKGROUND: Although it is usually possible to differentiate atypical AVNRT from ORT using a septal accessory pathway, a definitive diagnosis is occasionally elusive. METHODS: In 30 patients with atypical AVNRT and 44 patients with ORT using a septal accessory pathway, the right ventricle was paced at a cycle length 10 to 40 ms shorter than the tachycardia cycle length (TCL). The ventriculo-atrial (VA) interval and TCL were measured just before pacing. The interval between the last pacing stimulus and the last entrained atrial depolarization (stimulus-atrial [S-A] interval) and the post-pacing interval (PPI) at the right ventricular apex were measured on cessation of ventricular pacing. RESULTS: All 30 patients with atypical AVNRT and none of the 44 patients with ORT using a septal accessory pathway had an S-A-VA interval >85 ms and PPI-TCL >115 ms. CONCLUSIONS: The S-A-VA interval and PPI-TCL are useful in distinguishing atypical AVNRT from ORT using a septal accessory pathway.