房室结改良法射频消蚀治疗房室折返性心动过速初探（附二例报告）

按常规方法射频消蚀（ＲＦＣＡ）治疗房室折返性心动过速（ＡＶＲＴ），二例右侧隐匿性旁道未阻断。改用下位法改良房室结（ＡＶＮ），在Ｈ波完全消失处放电。结果：延长了正向房室传导有效不应期（ＥＲＰ），ＡＶＲＴ不能诱发。提示：ＡＶＮ改良法可作为ＲＦＣＡ治疗ＡＶＲＴ的补充方法。     

食管心房调搏对儿童室上性心动过速的诊断

３４例阵发性室上性心动过速（室上速）患儿经食管心房调搏检查，诊断为房室结折返１３例。快慢径有效不应期分别为３３７±５９．４６ｍｓ和２７８±７１．２４ｍｓ（Ｐ＜０．０５）；传导时间分别为２２０±５０ｍｓ和３０８±５８．０９ｍｓ（Ｐ＜０．０５）。旁室旁道折返１９例，其中６例为隐性，旁道前向有效不应期２００～３２０ｍｓ，与年龄呈正相关，但无显著性。自律性房住心动过速２例。儿童ＳＶＴ以房室折返为主，测定ＰＶ１－ＰＥ时距及ＲＰＥ间期有助于鉴别折返性室上速的类型及旁道位置。房室结折返ＰＶ１－ＰＥ时距近于零，房室折返为３４．２９±８．５ｍｓ．左侧旁道为正值，右侧为负值。但ＰＶ１有时辨认不满意，有局限性。房室结折返ＲＰＥ间期＜７０ｍｓ．而旁路折返则＞７０ｍｓ。     

PV1—PE值对不同部位房室旁束所致室上速的诊断意义

本文通过食管心房起搏与心内电生理对照研究６６例正向型房室折返性心动过速（ＯＡＶＲＴ）和慢－快型房室结折返性心动过速（ＡＶＮＲＴ）的ＰＶ１－ＰＥ时距。结果显示在绝大部分病例中，左侧不同部位游离壁旁束参与的ＯＡＶＲＴ，ＰＥ明显领先于ＰＶ１；右侧不同部位游离壁旁束参与的ＯＡＶＲＴ，ＰＶ１明显领先于ＰＥ；慢－快型ＡＶＮＲＴ时ＰＥ和ＰＶ１几乎同时出现；而当左侧旁束位于左前侧壁，右侧旁束位于右后侧壁，并伴有心房增大时，可不符合上述规律。ＰＶ１－ＰＥ绝对值２５ｍｓ可作为鉴别ＯＡＶＲＴ与ＡＶＮＲＴ的定量指标。     

食管心房调搏指标诊断室上性心动过速价值的评定

以射频消融结果为依据，评定Ｓ＿２Ｒ跃增值和ＲＰ＿Ｅ时距对４８例慢－快型房室结折返性心动过速（Ｓ－Ｆ型ＡＶＮＲＴ）和１４１例顺向型房室折返性心动过速（Ｏ－ＡＶＲＴ）患者的诊断及鉴别诊断价值，并讨论两类心动过速食管调搏的定量判别标准。结果表明：（１）Ｓ＿２Ｒ跃增以≥６０ｍｓ诊断ＡＶＮＲＴ为宜，但有一定局限性，其敏感性、特异性、诊断价值分别为９１．６％、８５．８％、７２．８％。（２）ＲＰ＿Ｅ时距≤７０ｍｓ和＞７０ｍｓ分别对Ｓ－Ｆ型ＡＶＮＲＴ、Ｏ－ＡＶＲＴ的诊断及鉴别诊断价值较高。敏感性、特异性、诊断价值分别为９３．８％、１００％、１００％与１００％、９３．８％、９７．９％．（３）少数（１７％）右侧壁旁道逆传性心动过速ＲＰ＿Ｅ／Ｐ＿ＥＲ可＞１．０。（４）Ｓ－Ｆ型ＡＶＮＲＴ与Ｏ－ＡＶＲＴ的定量判别Ｓ＿２Ｒ跃增、ＲＰ＿Ｅ标准宜分别取≥６０ｍｓ、≤７０ｍｓ与＜６０ｍｓ、＞７０ｍｓ。     

射频消融的临床应用

对２１例阵发性室上性心动过速（ＰＳＶＴ）患者施行导管射频消融（ＲＦＣＡ），其中１０例为预激综合征并房折返性心动过速（ＷＰＷ并ＡＶＲＴ），１０例为房室结双径路并房室结折返性心动过速（ＡＶＮＤＰ并ＡＶＮＲＴ），１例为房内折返性心动过速（ＩＡＲＴ）。经ＲＦＣＡ预激旁路和房室结改良有１８例获得成功，成功率８５．７％。无并发症，随访１～６个月未见复发者。     

从慢径消融发生的交界区心律试探房室结双径的本质

７６例慢－快型房室结折返性心动过速（ＡＶＮＲＴ）患者接受房室结慢径消融术。６５例慢径阻断、９例双径存在但ＡＶＮＲＴ不能诱发、２例快径阻断。慢径阻断后，除快径的前传有效不应期（ＥＲＰ）缩短（２８７．０±７９．０ｍｓｖｓ３４４．０±８７．０ｍｓ，Ｐ＜０．０１）外，房室传导的文氏点、２１阻滞点、室房传导的１１点、快径逆传ＥＲＰ、前传和逆传功能不应期均无明显改变。共放电８４１次，其中无交界区心律的３１７次放电，无一次消融成功。６５例慢径阻断者，交界区心律减少或消失。以上结果提示快径和慢径可能是两条各具电生理特性的传导纤维。     

国人室上性心动过速的性别特征及逆行P波对其折返径路的诊断价值

对９０例室上性心动过速（ＳＶＴ）患者的性别特征与逆行Ｐ波（Ｐ＇）分析结果发现：国人隐匿性房室旁道（ＣＡＰ）多于房室结双通道（ＤＡＶＮＰ），前者以男性为主，后者以女性为主；约２／３的旁道位于左游离壁（ＬＦＷ），１／３位于间隔及右游离壁，ＬＦＷ男性多见，间隔旁道女性多见；房室折返性心动过速Ｐ＇明显且Ｒ－Ｐ＇≥７０ｍｓ，房室结折返性心动过速多无Ｐ＇或Ｒ－Ｐ＇＜７０ｍｓ；Ｐ＇和Ｒ－Ｐ＇对ＡＶＲＴ和ＡＶＮＲＴ的手术前后诊断符合率为１００％。提示：心电图正常者，ＳＶＴ时Ｐ＇明显的男性，多为ＣＡＰ，且多在ＬＦＷ；ＳＶＴ时无Ｐ＇的女性，多为ＤＡＶＮＰ。     

房室折返和房室结内折返性心动过速逆行P波的临床意义

作者根据临床心内电生理检查法分析房室折返性心动过速（ＡＶＲＴ）和房室结内折返性心动过速（ＡＶＮＲＴ）的心电图，发现逆行Ｐ波（Ｐ＇）区别ＡＶＲＴ与ＡＶＮＲＴ及对房室旁道（Ａｐ）初步定位准确性高，简便迅速，有较大的临床意义。     

快-慢型房室结折返性心动过速的电生理特征和射频消融治疗

报道８例快－慢型房室结折返性心动过速（ＡＶＮＲＴ）的电生理特征及射频消融治疗。其中３例为慢－快型ＡＶＮ－ＲＴ射频消融改良慢径后出现的快－慢型ＡＶＮＲＴ。８例均经消融慢径而成功终止心动过速。平均放电次数３±１．１次、平均放电时间１２０±３０．４ｓ、平均放电功率３０±１１Ｗ。随访６～２４个月，无复发。快－慢型ＡＶＮＲＴ具有以下临床电生理特征：①快径不应期短、慢径不应期长。②心内电刺激无房室结双径路现象。③心动过速能由心房刺激诱发。④心动过速时ＡＨ间期＜ＨＡ间期，冠状窦近端Ａ波最提前。熟悉快－慢型ＡＶＮＲＴ的电生理特征，对于鉴别房性心动过速及右后间隔旁道参与的房室折返性心动过速十分重要，也是指导快－慢型ＡＶＮＲＴ射频消融成功的关键。     

房室结折返性心动过速患者房室结功能曲线连续 …

分析房室结折返性心动过速（ＡＶＮＲＴ）中房室结功能曲线呈连续性者的电生理特点。将ＡＶＮＲＴ分为房室结功能曲线连续组（Ⅰ组）及房室结功能曲线不连续组（Ⅱ组），行慢径消融，进行消融前后和组间的电生理比较，分析房室结功能曲线呈连续性者的特点。结果：Ⅰ组心房程序刺激对ＡＶＮＲＴ的诱发率仅４２％（５／１２），低于Ⅱ组的６６％（２３／３５）。Ⅰ组房室结前传有效不应期（ＥＲＰ－ＡＶＮ）消融前后无显著变化（２１８     

Sequential dual chamber extrastimulation: A novel pacing maneuver to identify the presence of a slowly conducting concealed accessory pathway

BACKGROUND: Transient VA block can be created in the AV node (AVN) when an atrial extrastimulus is delivered at the AVN effective refractory period (ERP) due to anterograde concealed conduction. OBJECTIVE: We hypothesized that ventricular stimulation during pacing-induced AVN refractoriness could identify concealed accessory pathways (APs) that remain hidden with standard maneuvers. METHODS: Patients undergoing electrophysiological study for supraventricular tachycardia were screened for presence of an AP using standard pacing maneuvers and/or V pacing during adenosine infusion. The dual-chamber sequential extrastimulation maneuver consisted of an 8-beat drive train of simultaneous AV pacing at 600 msec, followed by an A2 delivered at AVN ERP, followed by a V2 delivered at the drive train cycle length (600 msec). Repeat drives were then performed with decrements of 10 msec for V2 until VA block was seen. Retrograde AVN and AP ERP were recorded with standard (V1, V2) and dual-chamber extrastimulation (A1/V1, A2, V2). Patients with an AP identified with standard pacing, manifest pre-excitation, or A ERP < AVN ERP were excluded. RESULTS: Fourteen patients with and 19 patients without an AP were studied. In all patients with an AP, exclusive VA conduction over the AP, without fusion, was seen with the described pacing maneuver. In patients without an AP, retrograde AV nodal ERP was extended by a mean of 138 +/- 46 msec (range 50 to 210 msec) with the A2. Anterograde concealed conduction into the AP was also seen in some patients who showed AP conduction during standard V1V2 pacing (mean retrograde extension of ERP 12 +/- 8 msec, range 0 to 20 msec). CONCLUSION: Dual-chamber sequential extrastimulation is a useful maneuver for identifying slowly conducting APs not revealed with standard pacing maneuvers because of an ERP and conduction time similar to the AVN. The maneuver uses anterograde concealed conduction to prolong AVN refractoriness much more than that of a concealed AP, thereby allowing the AP to become manifest with the V2.     

Clinical electrophysiologic effects of lorcainide in patients and its effect on the conduction of accessory pathway in Wolff-Parkinson-White syndrome

The electrophysiologic effects of the intravenous administration of a new antiarrhythmic drug, lorcainide, were evaluated by programmed electrical stimulation of the heart in 20 patients with and without Wolff-Parkinson-White (WPW) syndromes. Lorcainide shortened the sinus cycle length from 721.0 +/- 125.9 to 649.5 +/- 100.1 ms (P less than 0.001), but did not influence sinus node function and AV node conduction and refractoriness, slightly increased atrial effective period (ERP) (P less than 0.02) and did not change ventricular ERP (P less than 0.2), obviously lengthened atrial conduction time, H, H-V interval and the width of V wave. Lorcainide caused complete antegrade block of the accessory pathway (AP) in six of 9 WPW patients and resulted in exclusive conduction over the AV nodal. His conduction in two patients with atrial flutter. It also prolonged the retrograde conduction time and refractoriness of AP, and prevented initiation of orthodromic atrioventricular tachycardia (O-AVRT) in six of 12 patients by blocking of the retrograde conduction of the AP, increased the cycle length of tachycardia from 321.7 +/- 43.6 to 361.7 +/- 54.9 ms (P less than 0.005) by marked prolongation of retrograde AP conduction time in 6 patients in whom O-AVRT could still be induced. It is concluded that intravenous lorcainide does not affect sinus node and AV node function, slightly influences atrial and ventricular refractoriness, obviously suppresses atrial, His bundle and intraventricular conduction, and is an effective antiarrhythmic drug for patients with WPW by blocking both the antegrade and retrograde conduction of the AP.     

Clinical implications of “pure” Hisian pacing in addition to para-Hisian pacing for the diagnosis of supraventricular tachycardia

BACKGROUND: Para-Hisian pacing is an effective method of differentiating between pathways for retrograde conduction over the accessory pathway (AP) and over the atrioventricular node (AVN). When performing para-Hisian pacing, the pacing spike sometimes captures only the His bundle, which we named "pure" Hisian pacing (Hc). OBJECTIVE: We evaluated the significance of pure Hisian pacing for predicting the pathways of ventriculoatrial conduction. METHODS: In 62 patients with supraventricular tachycardia, both para-Hisian and pure Hisian pacing were carried out during the sinus rhythm, resulting in three different types of electrocardiographic complexes with wide (local ventricular myocardial capture), slightly narrow (both local myocardial and His bundle capture), and very narrow QRS widths (Hc). A change of atrial activation sequence as demonstrated by these pacing modes indicated the presence of multiple retrograde pathways. The diagnosis of retrograde pathways by para-Hisian pacing with or without Hc was evaluated. RESULTS: In 22 patients with AVN reentrant tachycardia, para-Hisian pacing alone was able to correctly predict ventriculo-atrial conduction exclusively through the AVN without requiring findings from Hc. In 40 AP patients, para-Hisian pacing showed a pattern of retrograde conduction through the AVN in six, through both the AVN and AP in 10, and through an AP in 24 patients. Four of these 24 patients were diagnosed as having multiple pathways (AP+AVN or dual APs) by the addition of Hc. CONCLUSION: Pure Hisian pacing can help disclose another pathway for retrograde conduction in AP patients, which is unpredicted by ordinary para-Hisian pacing.     

Diagnostic significance of the morphological change in the atrial electrogram during Para-Hisian pacing

Para-Hisian pacing (PHP), a pacing method to differentiate between conduction occurring over an accessory pathway (AP) from that over the atrioventricular node (AVN), is assessed essentially by comparing the timing in the atrial electrogams. Morphological change in the atrial electrograms is often observed during PHP, but its significance has not been investigated. Prior to the catheter ablation procedure, PHP was performed in 52 patients with an AP and in 36 patients with AV nodal reentrant tachycardia (AVNRT). The morphological change in the atrial electrograms, which was retrospectively assessed between the His bundle and proximal right bundle branch (HB-RB) captured and non-captured beats, was identified in 15 of 52 patients with an AP and in 26 of 36 patients with AVNRT. The atrial electrogram in the 6 of these 15 AP patients changed its morphology without overlapping the ventricular electrogram. All 6 AP patients exhibited a PHP pattern with the presence of 2 retrograde conduction routes, an AP and the AVN. In the patients demonstrating no morphological change in the atrial electrogram, 33 of 37 AP patients and all 10 AVNRT patients had only one retrograde conduction route. Morphological change in the atrial electrogram without overlapping the ventricular electrogram seems to have diagnostic significance indicating the presence of both AP and AVN conduction.     

A clinical study of induction rate of atrioventricular reciprocating tachycardia in WPW syndrome]

The differences in induction rate of atrioventricular reciprocating tachycardia (AVRT) were analyzed in 76 consecutive patients of WPW syndrome with tachycardia attack, confirmed by either ECG or history, and who underwent electrophysiological study. AVRT was induced by programed electrical stimulation in 72% of patients with manifest WPW syndrome, in 77% of patients with intermittent WPW syndrome, and in 96% of patients with concealed WPW syndrome, respectively. There was a significant difference in induction rate between manifest WPW syndrome and concealed WPW syndrome (p less than 0.05). Induction rate of AVRT in patients with accessory pathway (AP) located in the ventricular septum was significantly lower (50%) than in patients with AP located in the left ventricle (88%) and in the right ventricle (72%) (p less than 0.05). Ventricular atrial conduction was found in only 56% of patients with AP located in the ventricular septum, while it was found in 94% of patients with AP located in the left ventricle, and in 100% of patients with AP located in the right ventricle (p less than 0.05). There were no significant differences in antegrade effective refractory periods of atrioventricular node and AP between patients with and without inducible AVRT. There was also no significant difference in the retrograde effective refractory periods of AP between patients with or without inducible AVRT. We concluded that the induction rate of AVRT would be affected by the location of AP and the mode of delta wave appearance in the surface electrocardiogram.     

Electrophysiological determinants of antidromic reentry induced during atrial extrastimulation. Insights from a pacing model of Wolff-Parkinson-White syndrome

The electrophysiology of antidromic reentry, a less common phenomenon than orthodromic reentry, remains a poorly understood aspect of the Wolff-Parkinson-White (WPW) syndrome. We used a pacing model of ventricular preexcitation in patients without WPW, so that electrophysiological events in the normal pathway during atrial extrastimulation (A1-A2 technique) could be precisely delineated without the obscuring effect of an actual accessory pathway. Ventricular preexcitation was simulated by an A1-V1 sequential basic drive with A2-V2 extrastimulation at progressively shorter A1-A2 (equal to V1-V2) coupling intervals. At each coupling interval tested within the zone of atrioventricular (A-V) nodal effective refractory period (since anterograde block of A2 was considered mandatory for manifestation of antidromic reentry), responses were assessed after A2 alone (method I), V2 alone (method II), and A2 plus V2 (method III, the complete preexcitation model). The entire pacing protocol was performed at two A-V intervals, short (50 msec) and long (150-180 msec), thereby simulating different proximities between the A pacing site and "accessory pathway" location. Of 47 consecutive unmedicated patients screened for the study protocol, 38 failed to meet minimal prerequisites for possible initiation of antidromic reentry because of failure in 18 (38% of total) to achieve anterograde A-V nodal block of A2, even though 1:1 ventriculoatrial conduction to cycle lengths less than or equal to 500 msec (less than or equal to 400 msec in 12) was present; and poor or absent ventriculoatrial conduction in the others. The nine remaining candidates underwent the full pacing protocol. Antidromic reentry (retrograde atrial response following V2 in method III) was observed in only two cases (4% of total), and both were associated with retrograde His-Purkinje system delays (documented by method II) occurring in tandem with a long A-V interval, thereby allowing for completion of retrograde A-V nodal recovery after penetration by A2. Indeed, such a prolonged recovery time prevented initiation of antidromic reentry in six of the nine patients (proven by intact ventriculoatrial conduction in method II). Retrograde A-V nodal block of V2, independent of A2, prevented an antidromic echo in one case. Findings in our model help to clarify the various factors, including specific anterograde and retrograde A-V nodal properties; anatomic relation between the accessory and normal pathways; and the retrograde His-Purkinje system delays, that must prevail in a concerted fashion to permit the initiation of antidromic reentry during the A1-A2 technique in patients with the WPW syndrome.     

Utilization of Retrograde Right Bundle Branch Block to Differentiate Atrioventricular Nodal from Accessory Pathway Conduction

Introduction: Defining whether retrograde ventriculoatrial (V-A) conduction is via the AV node (AVN) or an accessory pathway (AP) is important during ablation procedures for supraventricular tachycardia (SVT). With the introduction of ventricular extrastimuli (VEST), retrograde right bundle branch block (RBBB) may occur, prolonging the V-H interval, but only when AV node conduction is present. We hypothesized that when AP conduction was present, the V-A interval would increase less than the V-H interval, whereas with retrograde nodal conduction, the V-A interval would increase at least as much as the V-H interval.
Methods and Results: We retrospectively reviewed the electrophysiological studies of patients undergoing ablation for AVN reentrant tachycardia (AVNRT) (55) or AVRT (50), for induction of retrograde RBBB during the introduction of VEST, and the change in the measured V-H and V-A intervals. Results were found to be reproducible between independent observers. Out of 105 patients, 84 had evidence of induced retrograde RBBB. The average V-H interval increase with induction of RBBB was 53.7 ms for patients with AVRT and 54.4 ms for patients with AVNRT (P = NS). The average V-A interval increase with induction of RBBB was 13.6 ms with AVRT and 70.1 ms with AVNRT (P < 0.001). All patients with a greater V-H than V-A interval change had AVRT, and those with a smaller had AVNRT.
Conclusions: Induction of retrograde RBBB during VEST is common during an electrophysiological study for SVT. The relative change in the intervals during induction of RBBB accurately differentiates between retrograde AVN and AP conduction.     

食管心房调搏诱发与终止房室折返性心动过速的研究

目的探讨经食管心房调搏诱发与终止房室折返性心动过速的价值。方法选择255例有心动过速发作史,并且既往心电图证实有阵发性室上性心动过速(PSVT)的患者行食管心房调搏检查。结果在被检的255例患者中诱发房室折返性心动过速229例,占89.8%(其中顺向型217例,占94.8%,逆向型12例,占5.2%)。诱发成功的最佳刺激方法为程序期前刺激法(S1S2、S1S2S3),诱发率为88.2%。诱发的必备条件是旁路有效不应期长于房室结有效不应期。在诱发房室折返性心动过速的229例中215例经电刺激成功终止,转复为窦性心律,成功率为93.9%,其中64例采用短阵快速刺激一次性成功终止,转复成功率达100%。结论食管心房调搏能有效地诱发与终止房室折返性心动过速,诱发顺向型房室折返性心动过速的关键因素是旁路不应期大于房室结有效不应期,终止发作的最有效的刺激方法为短阵快速刺激。本法可作为急诊终止阵发性室上性心动过速的首选方法。     

Atrial fibrillation and effective refractory period of the pulmonary vein ostia.

BACKGROUND: The pathogenesis of atrial fibrillation (AF) is not completely understood. The role of pulmonary veins (PV) in AF initiation is documented, and the recent demonstration of persistent fibrillatory activity in an isolated PV suggests that the PV play a role in the maintenance of AF. OBJECTIVE: Since AF is facilitated by multiple reentry circuits in atrial tissue with short effective refractory periods (ERP) and prolonged conduction times, we investigated whether PV have shorter ERP compared with the left atrium (LA). POPULATION AND METHODS: The study population consisted of five male patients, between 45 and 78 years of age, with normal sized LA; three had coronary artery bypass surgery (and no previous history of atrial arrhythmias) and two had paroxysmal lone AF refractory to antiarrhythmic drugs and were referred for percutaneous ablation with radiofrequency energy. In the surgical patients, epicardial bipolar pacing wires were inserted in the PV ostia and LA roof at the end of the procedure. Post-operatively, the pacing wires were used to determine atrial thresholds and ERP in the PV ostia and LA roof. In the AF patients, atrial thresholds and ERP at these locations were obtained with the mapping/ablation catheter before and after PV isolation. ERP were determined with a basic pacing cycle length of 500 ms and a single extrastimulus with an initial coupling interval of 350 ms, gradually decreased (10 ms at a time) until atrial capture failure or AF induction. RESULTS: ERP in the LA roof were longer than 210 ms. The shortest ERP was always obtained in a PV ostium, with the shortest in the left PV ostia. The ERP values of the right inferior PV most resembled those of the LA roof. In patients referred for ablation, AF was induced when PV ostia with ERP shorter than 200 ms were stimulated. CONCLUSION: In the present study, the ERP of PV ostia were shorter than LA ERP, possibly explaining not only the presence of ectopic foci in the PV ostia, but also sustained fibrillatory activity in isolated PV, despite conversion of the atria to sinus rhythm. This fact may also explain the higher success rate and the preference for PV isolation in AF ablation.