Repolarization abnormalities after catheter ablation of accessory atrioventricular connections with radiofrequency current

The purpose of this study was to evaluate the serial changes in T wave configuration in patients undergoing successful radiofrequency catheter ablation of accessory atrioventricular (AV) connections. Twenty-nine consecutive patients with overt preexcitation and 16 patients with a concealed accessory atrioventricular (AV) connection were included. An electrocardiogram (ECG) was recorded before ablation and 15 min, 1 or 2 days and 1 and 3 months after ablation. Postablation T wave abnormalities occurred in 22 (76%) of the 29 patients who had overt pre-excitation but in none of the 16 patients with a concealed accessory AV connection. The T wave abnormalities were not related to myocardial necrosis or echocardiographic abnormalities. The ECG location and severity of T wave changes were dependent on the accessory AV connection location and degree of baseline pre-excitation, respectively. Fourteen of 19 patients with a posteriorly located AV connection (left, right or septal) had T wave inversion or flattening in the inferior leads and 3 patients had precordial T wave peaking. Two patients with an anteroseptal AV accessory connection had both inferior T wave inversion or flattening and precordial T wave peaking. Among seven patients with a manifest left lateral accessory AV connection, two had lateral T wave inversion or flattening and two had precordial T wave peaking. There was 95% concordance between the directional change of the T wave after ablation and the direction of the delta wave on the baseline ECG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Repolarization abnormalities after catheter ablation of differently located overt accessory pathways.

PURPOSE: Electrical repolarization abnormalities are usually seen after radiofrequency catheter ablation in overt accessory atrio-ventricular pathways. These abnormalities have been recognised as "cardiac memory". The aim of this study was to assess the relationships between electrical repolarization abnormalities and the location of the accessory atrioventricular pathway in the atrio-ventricular junction. We also assessed the relationship between electrical repolarization abnormalities and the degree of ventricular preexcitation. MATERIAL AND METHODS: Our group consisted of 45 patients with overt and persistent preexcitation who were successfully submitted to radiofrequency catheter ablation. Mean age was 38.9 +/- 14.9 years (14 to 64), 28 of whom (62.2%) were male and 17 (37.8%) female. The location of accessory pathways the was left lateral in 14 patients, right posteroseptal in 14 patients, right mesoseptal in eight patients, right anteroseptal in four patients and other locations in the remaining four. Surface electrocardiograms were performed immediately following ablation, 24 hours later and three or more months after the procedure. RESULTS: T wave abnormalities (flattened, inverted or peaked) were detected on the first day in 51% of patients, being more frequent after right accessory pathway ablation (86.9% versus 13.1% in left accessory pathways). These electrocardiographic changes were particularly frequent in patients with right mesoseptal (5/8, 62.5%) and posteroseptal (13/14, 93.3%) pathways, of which 62.5% and 71.5%, respectively, showed marked preexcitation before ablation. These findings were significantly different from those observed in patients with left lateral pathways--only 35.7% showed marked preexcitation and only two of fourteen patients (14.3%) presented T wave abnormalities after ablation. After the third month, most of the patients that had undergone successful ablation presented completed electrocardiographic normalization. CONCLUSIONS: Patients undergoing radiofrequency catheter ablation for right accessory pathways show more frequently repolarization abnormalities than those submitted to ablation of the left lateral accessory pathways. The occurrence of these changes after preexcitation resolution may depend on the degree of previous preexcitation.     

Relationship between QRS duration and repolarization abnormalities in patients with wolff-parkinson-white syndrome

Marked T wave abnormalities in 12-lead electrocardiograms often appear after radiofrequency ablation in patients with Wolff-Parkinson-White (WPW) syndrome. Durations of the QRS complex before ablation have been reported to be significantly greater in patients with repolarization abnormalities after ablation than in those with normal repolarization. However, there has been no report concerning the relationship between QRS duration and repolarization abnormalities before ablation. It has been reported that QRST isointegral maps are dependent on local cellular repolarization properties but largely independent of activation sequence, and that they provide quantitative information about repolarization abnormalities. Isointegral maps were constructed from data recorded in 34 patients with WPW syndrome and QRS durations of 0.1 second or longer (21 patients with left-sided accessory pathways and 13 with right-sided pathways) in order to investigate the relationship between QRS duration and abnormalities in repolarization properties during preexcitation. Body surface ECGs were recorded with an 87-lead system at a sampling interval of 1 ms. The QRST values (mean ± 2SD) from 607 normal individuals were taken to represent the normal range. The area with abnormally low QRST values was designated as the −2SD area and the sum of the QRST values (ΣQRST) in this area was calculated. The QRS duration was found to be significantly related to ΣQRST. These results demonstrate that the patients with WPW syndrome had abnormalities in local repolarization properties that were significantly related to QRS duration during preexcitation. The degree of preexcitation may be important in producing these abnormalities in patients with manifest WPW syndrome. This may result in T wave abnormalities after ablation of the accessory pathway attributable to cardiac memory.     

预激综合征射频消融术后心电图电张调整性T波及J-ST段特征分析

目的探讨预激综合征射频消融房室旁道后心电图出现电张调整性T波及J-ST段的特征及其发生机制。方法45例持续性预激综合征患者,对比射频消融术前后心电图,总结和分析术后电张调整性T波、J波以及ST段变化的发生规律和特征。结果45例中射频消融术后出现电张调整性T波改变有27例,间隔部和左前壁旁道消融后电张调整性T波出现率最高(达100%),电张调整性T波主要分布于下壁导联(Ⅱ、Ⅲ、aVF)和高侧壁导联(Ⅰ、aVL);下壁导联电张调整性T波倒置深度Ⅲ>aVF>Ⅱ(P<0.01),高侧壁导联aVL>Ⅰ。此外尚可出现J-ST改变,表现为J点抬高、J波和ST段水平或弓背向下型抬高,总发生率高于同期隐匿性旁道消融组(42.2%vs3.5%,P<0.01)。结论预激综合征射频消融术后电张调整性T波的出现取决于预激时QRS波形态;射频消融术后心电图可出现类似早期复极综合征的J-ST段改变。     

Successful high-frequency current ablation of three accessory conduction pathways in a single session]

A case is presented of a 25-year-old symptomatic male with Wolff-Parkinson-White syndrome and three overt accessory atrioventricular connections which were all diagnosed and ablated during the same session. A discordant preexcitation pattern between delta wave and QRS axis was found on the surface electrocardiogram, indicating the presence of two or more accessory pathways. During atrial pacing the appearance of a changing QRS morphology and alternating delta wave suggested the presence of an additional left-sided pathway. After ablation of a right anteroseptal pathway, a second pathway was found located in the left lateral position and was successfully ablated. The final pathway became evident only after the ablation of the first two and was found to be located in a right midseptal position. This pathway was also ablated during this session. There were no complications and the patient remained asymptomatic during an 11-month follow-up.     

Changes in repolarization properties with long-term cardiac memory modify dispersion of repolarization in patients with Wolff-Parkinson-White syndrome

INTRODUCTION: Transient T wave changes after cessation of preexcitation have been attributed to cardiac memory. However, there have been no reports on the effects of long-term cardiac memory on repolarization dispersion before and after catheter ablation in patients with Wolff-Parkinson-White (WPW) syndrome. METHODS AND RESULTS: We investigated 47 patients with an accessory pathway (AP; 24 manifest left-sided, 14 manifest right-sided, and 9 concealed left-sided). Repolarization dispersion was analyzed by two methods, recovery time (RT) dispersion and newly proposed T wave width (WT), from 87-lead body surface maps before, 1 day after, and 7 days after catheter ablation. RT dispersion and WT were significantly correlated before, 1 day after, and 7 days after catheter ablation (r = 0.78). In patients with preexcitation, RT dispersion and WT increased significantly (P < 0.05) 1 day after catheter ablation (178 +/- 32 msec and 172 +/- 30 msec) compared with those before (154 +/- 24 msec and 156 +/- 18 msec) and 7 days after catheter ablation (147 +/- 19 msec and 156 +/- 16 msec), respectively. However, there were no significant changes in RT dispersion and WT before and after catheter ablation in concealed WPW syndrome. CONCLUSION: The findings suggest that the abrupt changes in activation sequence increase repolarization dispersion in the presence of previous cardiac memory, and that the dispersion decreases days or weeks after alteration of activation sequence by catheter ablation, with development of new cardiac memory in patients with manifest WPW syndrome.     

Electrocardiographic abnormalities after radiofrequency catheter ablation of accessory bypass tracts in the Wolff-Parkinson-White syndrome.

Repolarization abnormalities on surface electrocardiograms have been described after loss of ventricular preexcitation in some patients with the Wolff-Parkinson-White syndrome. Radiofrequency catheter ablation of overt accessory pathways provides a unique opportunity to study this phenomenon. In this study, serial electrocardiograms were obtained before and after radiofrequency ablation of manifest accessory pathways in 19 patients, of concealed accessory pathways in 6 and after radiofrequency atrioventricular nodal modification in 12. Seven patients undergoing manifest right-sided accessory pathway ablation had left superior frontal plane T-wave axis deviations after ablation (-42 +/- 13 degrees). No patient with a manifest left-sided or concealed accessory pathway, or atrioventricular nodal modification had T-wave abnormalities after ablation; however, left anterior fascicular block and incomplete right bundle branch block each occurred in 1 patient with left accessory pathway ablation. Repolarization abnormalities observed after ablation were similar to T-wave abnormalities during the absence of preexcitation before ablation and persisted up to 5 weeks after the procedure. Patients with repolarization abnormalities after ablation had significantly longer preexcited QRS durations than those without such changes, suggesting that the initial contribution of the pathway to ventricular activation is an important determinant of T-wave changes after ablation. The proposed mechanism for repolarization abnormalities after ablation is the phenomenon of T-wave "memory."     

显性房室旁道射频消融术后T波改变的临床意义

通过对房室旁道 (简称旁道 )消融术后T波改变的动态观察 ,探讨其临床意义。 12 4例消融成功的单旁道患者分为隐匿性旁道组 (n =5 6 )、轻度预激组 (n =2 4)和明显预激组 (n =44 )。记录消融术前、术后即刻、术后 1h、术后 1天及随访 1～ 3个月期间 12导联心电图 ,比较评价消融术前后T波改变。消融术后超声心动图检查及测定心肌酶。结果 :术后 2 4h明显预激组 2 7例 (6 1% )T波明显改变 ,轻度预激组 4例 (17% )T波明显改变 (P <0 .0 1)。隐匿性旁道组无 1例T波改变。室间隔 (87% )及左侧旁道 (77% )消融术后T波改变多于右侧旁道 (36 % )。T波改变与消融能量及心肌酶升高程度无关 ,与术前预激程度及旁道部位有关。术后 1～ 3个月T波改变者均完全恢复正常。结论 :提示显性旁道射频消融术后T波改变为电张调整性T波改变 ,非心肌损伤所致。     

预激综合征对QRS波终末向量的影响

为探讨预激综合征对QRS波终末向量的影响和终末向量改变的临床意义 ,选择经射频消融 (RFCA)术治愈的显性预激综合征患者 12 9例 ,据旁道部位分 9组 :左前壁 (LA)、左侧壁 (LL)、左后壁 (LP)、右前壁 (RA)、右侧壁(RL)、右后壁 (RP)、右前间隔 (RAS)、右中间隔 (RMS)、右后间隔 (RPS) ,对比分析RFCA术前、后心电图。结果 :①与消融旁道后心电图对比 ,12 9例显性预激综合征均影响终末向量。②终末向量改变与旁道位置有关 :aVL(和Ⅰ )导联 :终末负向波振幅增加 ,或终末正向波变为负向波主要出现在LA、LL旁道 ;终末正向波振幅增加 ,或负向波振幅减小或变为正向波主要出现在LP、RA、RL、RP、RAS、RMS、RPS旁道。Ⅲ (和aVF)导联 :终末正向波振幅增加 ,或负向波变为正向波 ,或终末无变化主要出现在LA、LL、RA、RAS旁道 ;终末正向波变为负向波 ,或正向波振幅减小 ,或负向波振幅增加主要出现在LP、RL、RP、RMS、RPS旁道。V1导联 :终末负向波振幅减小或消失主要出现在LA、LL、LP旁道 ;终末负向波振幅增加主要出现在RA、RL、RP、RAS、RMS、RPS旁道。③终末向量改变与预激波有关 :aVL、Ⅰ、Ⅱ、aVF、Ⅲ、V1导联QRS波终末向量的变化与预激向量方向基本一致 (P <0 .0 1)。结论 :观察终末向量的改变可能有助于delta波不     

Concordance of distinguishing electrocardiographic features during sinus rhythm with the location of accessory pathways in the Wolff-Parkinson-White syndrome

Knowledge of the location of accessory pathways in patients with Wolff-Parkinson-White (WPW) syndrome is pertinent to patient management. Despite the recognition that features of delta waves present during maximal preexcitation reflect ventricular activation at different sites around the anulus fibrosus, the value of electrocardiographic patterns observed during sinus rhythm, when ventricular preexcitation is often not maximal for identifying accessory pathway locations, has not been determined. In this study, 12-lead electrocardiograms recorded during sinus rhythm from 66 patients with WPW syndrome were analyzed for delta-wave polarity, QRS axis in the frontal plane, the pattern of precordial R-wave transition, and concordance between electrocardiographic patterns and the site of the accessory pathway determined using catheter and intraoperative computer mapping. Electrocardiograms from patients with left lateral sites showed negative delta waves in leads I or aVL, a normal QRS axis and early precordial R-wave transition (20 of 24 patients); left posterior sites manifested negative delta waves in II, III and aVF and a prominent R wave in V1 (14 of 16 patients); posteroseptal sites had negative delta waves in II, III and aVF, a superior QRS axis and an R less than S in V1 (all 16 patients); right free wall locations manifested negative delta waves in aVR, a normal QRS axis, and R-wave transition in V3-V5 (6 of 6 patients); and anterior septal sites had negative delta waves in V1 and V2, a normal QRS axis, and R-wave transition in V3-V5 (4 of 4 patients). Characteristic electrocardiographic patterns were not observed in 5 patients because of insufficient preexcitation. Each had a left lateral or left posterior pathway. Overall, the proposed electrocardiographic criteria derived during sinus rhythm identified correctly the accessory pathway location in 60 of 66 patients (91%). Thus, the electrocardiogram provides the physician with a reliable noninvasive means of regionalizing the location of accessory pathways in patients with WPW syndrome.     

房室旁路射频导管消融术中心脏记忆现象的分析

目的对房室旁路射频导管消融术(以下简称消融术)前后T波改变进行分析，以揭示影响T波改变的因素。 方法选择资料完整的显性房室旁路患者120例，隐匿房室旁路100例，所有患者均为单支房室旁路，术中旁路均阻断成功，男性170例，女性50例，年龄8～72(平均36±13)岁，均有术前及术后即刻同步十二导联心电图，显性房室旁路预激程度足够充分(预激波清晰，QRS波时限大于100ms)。按常规旁路消融方法，计算不同部位的显性及隐匿房室旁路消融术前后发生T波改变的百分率，比较不同部位显性房室旁路消融术前后发生T波改变的差异性，比较显性与隐匿房室旁路消融术前后发生T波改变的差异性。 结果不同部位的显性房室旁路消融术后发生T波改变无显著差异(右后侧壁100%，右后间隔100%，右侧其它部位93%，左后间隔100%，左侧其它部位90%，P＞0.05)，显性房室旁路与隐匿房室旁路(左侧隐匿房室旁路2%，右侧隐匿房室旁路20%)相比有非常显著差异(P＜0.01)。 结论消融术后发生T波改变是由于心脏记忆所致，与旁路部位、心肌损伤及自主神经功能变化无关，冠状动脉缺血不是显性房室旁路消融术后发生T波改变的主要原因。     

房室旁道射频消融后T波改变的临床观察

分析房室旁道射频消融术前后T波改变的影响因素 ,以揭示T波的改变机制。选择房室旁道患者 116例 ,其中显性旁道 82例、隐匿性旁道 34例。术中旁道均成功阻断 ,均为单支旁道 ,消融前后均无束支阻滞者。结果 :82例显性旁道患者有 79例 (96 % )有T波改变 ,而 34例隐性旁道患者无一例有T波改变 (P <0 .0 1) ;左、右显性旁道T波改变无显著性差异 (95 %vs 10 0 % ,P >0 .0 5 ) ;T波改变程度与预激程度有关 ;有T波改变和无T波改变患者消融时间 (116± 37vs 118± 5 2s)、能量 (2 7± 5vs 2 8± 7W)和消融后CK MB(2 0± 3vs 2 1± 5IU/L)差异无显著性 ,P均 >0 .0 5。结论 :射频消融术后T波改变由电张力调整所致 ,与心肌损伤无关。     

Electrocardiographic and electrophysiologic characteristics of midseptal accessory pathways

BACKGROUND : The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs. METHODS AND RESULTS: From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P=0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n = 10, V3; n = 7 and V4; n = 3) and LMS APs (leads V1; n = 1 and V2; n = 4) (P = 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP. CONCLUSIONS: Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs.     

Specific Electrocardiographic Features of Manifest Coronary Vein Posteroseptal Accessory Pathways

Coronary Vein Accessory Pathways. Introduction: Some posteroseptal accessory pathways (APs) can be successfully ablated by radiofrequency current only from inside the coronary sinus (CS) or its branches, because of an absolute or relatively epicardial location. The aim of this study was to identify ECG features of manifest posteroseptal APs requiring ablation in the CS or the middle cardiac veins (MCVs). Methods and Results: One hundred seventeen consecutive patients with manifest posteroseptal APs successfully ablated: (1) ≥ 1 cm deep inside the MCV (group MCV: n = 13); (2) inside the CS, including the area adjacent to the MCV ostium (group CS: n = 10); (3) at the right (group R: n = 60); or (4) the left posteroseptal endocardial region (group L: n = 34) were included. We reviewed delta wave polarity (initial 40 msec) and QRS morphology during sinus rhythm and atrial pacing as well as electrogram characteristics in these patients. The local target site electrogram in groups MCV and CS was characterized by a longer atrial to ventricular electrogram interval, suggesting a longer course of the pathway and more frequent recording of a presumptive AP potential compared to the group ablated at the right or left endocardium. The most sensitive ECG feature for group CS or group MCV was a negative delta wave in lead II in sinus rhythm (87%), but specificity (79%) and positive predictive value (50%) were relatively low. A steep positive delta wave in aVR during maximal preexcitation possessed the highest specificity and positive predictive value (98% and 88%, sensitivity 61%) which increased to 99% and 91%, respectively, when combined with a deep S wave in V₆ (R wave ≤ S wave). Conclusion: These data suggest that posteroseptal APs ablated inside the coronary venous system have highly specific features, including the combination of a steep positive delta wave in lead aVR and a deep S wave in lead V₆ (R wave ≤ S wave) during maximal preexcitation. The highest sensitivity is provided by a negative delta wave in lead II. These findings may be helpful for anticipating and planning an epicardial ablation strategy.     

Paraseptal Accessory Pathway in Wolff-Parkinson- White-Syndrom: Ablation from the Right,from the Left or within the Coronary Sinus/Middle Cardiac Vein?

Aims: In 1999 the consensus statement living anatomy of the atrioventricular junctions was published. With that new nomenclature the former posteroseptal accessory pathway (APs) are termed paraseptal APs. The aim of this study was to identify ECG features of manifest APs located in this complex paraseptal space.Methods and Results: ECG characteristics of all patients who underwent radiofrequency ablation of an AP during a 3 year period were analyzed. Of the 239 patients with one or more APs, 30 patients had a paraseptal AP with preexcitation. Compared to APs within the coronary sinus (CS) or the middle cardiac vein (MCV) the right sided paraseptal APs significantly more often showed an isoelectric delta wave in lead II and/or a negative delta wave in aVR. The left sided paraseptal APs presented a negative delta wave in II significantly more often compared to the right sided APs.Conclusions: According to the site of radiofrequency ablation, paraseptal APs are classified into 4 subgroups: paraseptal right, paraseptal left, inside the CS or inside the MCV. Subtle differences in preexcitation patterns of the delta wave as well as of the QRS complex exist. However, the definitive localization of APs remains reserved to the periinterventional intracardiac electrogram analysis.     

Usefulness of the thoracic circle in localizing the pre-excitation zone in Wolff-Parkinson-White syndrome

In this study thoracic circle lead electrocardiogram were recorded during sinus rhythm in 50 patients with Wolff Parkinson White Syndrome. We analyzed: delta wave polarity, QRS axis in the frontal plane, ventricular preexcitation, the pattern of precordial R wave transition and QRS morphology in the unipolar leads, also concordance between electrocardiographic patterns and the site of the accessory pathway determined during electrophysiological study. Electrocardiograms from patients with left lateral sites showed negative delta waves in leads LI or a VL, V7 to V9, positive delta waves in V3R to V9R, a normal QRS axis and early precordial R wave transition (20 of 23 patients). Left posterior sites manifested negative Delta waves in L3, a VF, V7 to V9, V7R to V9R and a prominent R wave in V1 (4 of 5 patients). Left posteroparaseptal sites had the same pattern plus negative delta waves in L2, a superior QRS axis, and RS or Rs morphology in V1 (3 of 3 patients). Right posteroparaseptal sites had negative delta waves in L2, L3, a VF, V3R to V9R, positive delta waves in V7 to V9, a superior QRS axis and an R greater than S in V1 (10 of 11 patients). Right free wall locations manifested negative delta waves in L3, a VR, V3R to V9R, positive delta waves in V7 to V9, a normal QRS axis and R wave transition in V3 to V5 with QS morphology since V3R to V9R (6 of 7 patients).(ABSTRACT TRUNCATED AT 250 WORDS)     

"Atypical" posteroseptal accessory pathway in Wolff-Parkinson-White syndrome

The posteroseptal accessory pathway in the Wolff-Parkinson-White syndrome is associated with a delta wave that is negative in the inferior electrocardiographic (ECG) leads and the occurrence of the earliest retrograde atrial activation near the orifice of the coronary sinus during atrioventricular (AV) reentrant tachycardia. Seventy-two patients with a posteroseptal accessory pathway underwent epicardial mapping before operative ablation. The earliest epicardial activation occurred at the posterosuperior process of the left ventricle in all patients. Dissection of the posteroseptal region (right atrial-left ventricular sulcus) resulted in permanent loss of preexcitation in 69 patients and failure to abolish preexcitation permanently in 3. At reoperation in two patients, preexcitation was abolished by discrete cryoablation of the left side of the interatrial septum near the AV node approached through the atrial septum in the normothermic beating heart. At reoperation, one patient had extensive AV node dissection. All patients have had permanent loss of preexcitation. The vast majority of posteroseptal accessory pathways ("typical") are epicardial and ablated by dissection of the posteroseptal region. Rarely, posteroseptal accessory pathways are "atypical" in that they are intraseptally located near the AV node on the left atrial endocardial surface.     

Catheter ablation of left posteroseptal accessory pathways and of long RP' tachycardias with a right endocardial approach

Fifty-four patients with a posteroseptal accessory connection and symptomatic tachycardias underwent catheter ablation of the anomalous pathway. Eight had the permanent form of reciprocating tachycardias (long RP' tachycardia) and 46 had a left posteroseptal preexcitation marked by a prominent R wave in lead VI. In 14 of 19 patients, ventriculoatrial conduction time during tachycardia lengthened in conjunction with functional left bundle branch block; this behaviour was significantly different from a series of patients with right posteroseptal preexcitation in which functional left bundle branch block lengthened the ventriculoatrial time in only one of 12 patients. A quadripolar electrode catheter was left within the proximal coronary sinus in order to locate the earliest atrial or ventricular activation site. The appropriate bipole was used as the radiographic and electrophysiological reference of the insertion of the accessory pathway. A catheter was then positioned on the septal side of the right atrium, outside the coronary sinus, so that atrial activity during reciprocating tachycardia and ventricular activity during preexcitation were synchronous with or earlier than that recorded within the proximal coronary sinus. Accessory pathway potential was not recorded in any patient. Early ventricular potential occurring --1.5 +/- 8 ms relative to delta wave onset was present at that site. In 38 patients, including 5 with permanent junctional tachycardia, high current (14 mA) pacing yielded direct ventricular paced QRS complexes (no delay spike-QRS) with a morphology similar to left posteroseptal maximal preexcitation. Slight movements of catheter position yielded significantly different pace-maps. One to eight 160 J cathodal shocks (510 +/- 213 J cumulative per patient) were delivered at this site in 61 sessions. Following fulguration, tachycardia recurred without drugs in only one patient over a follow-up period of 20 +/- 13 months. Asymptomatic intermittent preexcitation recurred in two patients. In all patients with long RP' tachycardia, the ablation procedure was successful without the need for drugs or permanent cardiac pacing. A long-term follow-up electrophysiological study in 18 patients demonstrated that conduction through the anomalous pathway was absent in 16 and deeply altered in the two patients with intermittent preexcitation; no tachycardia was inducible in any patient. In conclusion, catheter ablation of left posteroseptal accessory pathways is a feasible procedure using a right atrial approach outside the coronary sinus. This technique is also effective for the treatment of the permanent form of reciprocating tachycardia.     

预激综合征改变心室激动顺序的机制和临床意义

目的阐明预激综合征改变心室激动顺序的机制和临床意义。方法沿房室环将心脏分为10个区,每区10～30例预激综合征,共155例为研究组。测量射频导管消融（下称消融）前后QRS终末20ms波的极性和振幅。以隐匿性房室旁束24例为对照组,作同样测量。此外,研究组测量6波时间及消融前后的QRS时间。结果10区旁束皆有大于或等于两个导联出现QRS终末20ms波极性改变的病例,总改变率为832％,95％可信区间为0．77～0．89。与对照组比较,10个区域的QRS终末20ms波振幅在X、Y、Z3个轴向差异均有统计学意义（均P〈0．05）。左心室壁,室间隔和右心室壁3组的QRS时间分别是0．135±0．014s。0．135±0．016s和0．149±0．021s,右心室壁组显著长于室间隔组（P=0．001）和左心室壁组（P=O．000）。6波后的QRS时间〉消融后QRS时间的发生率左心室壁、室间隔和右心室壁3组分别为3615％、27.3％和5913％,右心室壁组显著高于室间隔组（P=O．001）和左心室壁组（P=O．022）。结论预激心室各区皆出现QRS终末向量改变,说明心室激动从开始到结束,都发生了顺序改变。其机制是预激导致心室失同步,并与正常径路顺传的激动发生广泛的干扰。由于心室激动顺序异常导致心室收缩与舒张顺序异常,预激综合征不可避免地改变了血流动力学和心功能。     

Detection of diastolic potentials around the mitral annulus of structurally normal human hearts

To examine the electrophysiologic characteristics of the subvalvular mitral region, we retrospectively searched for the presence of subvalvular diastolic potentials (DP) in 91 patients (mean age, 46.9 ± 16.6 years) who underwent catheter ablation of left-sided accessory pathways (AP). We detected low-amplitude (0.19 ± 0.09 mV) DP in 14 patients (15.4%), including 8 with overt preexcitation and 6 patients with concealed AP. The mean interval between ventricular electrogram and DP was 383 ± 46 ms (range, 306-475). DP were detected in 4 of 20 patients with antero-lateral, 3 of 38 with lateral, 4 of 12 with postero-lateral, 2 of 14 with posterior, and 3 of 10 patients with postero-septal AP. In 6 of 14 patients, DP were detected before ablation. In 4 of 8 patients with overt preexcitation, DP were consistently recorded after elimination of the delta wave, suggesting that they were not associated with AP conduction. In 6 of 11 patients, DP were observed during both sinus rhythm and ventricular pacing, suggesting that they were not artifacts. The electrophysiologic characteristics of clinically relevant DP around the mitral annulus suggest that, in normal human hearts, an anatomical substrate may be present around the mitral annulus.