Use of Adenosine Test for the Exclusion of Preexcitation Syndrome in Asymptomatic Individuals

Background: Resting electrocardiogram is a routine procedure for the identification of potentially fatal conditions, including preexcitation syndrome (PES). Intravenous adenosine is a sensitive and specific means of exposing inapparent pathways in such patients. Yet, it may not be sensitive when complete atrioventricular (AV) block is not achieved because a low dose of adenosine is used. We evaluated the yield of a high‐dose adenosine test that achieved complete AV nodal block for unmasking inapparent pathway in a healthy population. Methods: We retrospectively reviewed all Israeli air force (IAF) academy candidates who were referred to adenosine test based on a cardiologist's suspicion of PES. The results of the adenosine test were recorded, including the adenosine dose required to achieve complete AV block. The medical records of the subjects were reviewed to identify any adverse cardiovascular outcome. Results: Fifty‐nine subjects who underwent adenosine test were followed for 35.42 ± 24 months. Complete AV block was achieved in all subjects with an average adenosine dose of 22.51 ± 12.67 mg. None of the subjects had evidence of an inapparent pathway. All subjects completed military service without adverse outcomes. Conclusions: The vast majority of young patients with a short PR interval do not have evidence of an accessory pathway and have a favorable prognosis. Thus, the yield of adenosine test in young combat recruits is questionable. Yet, if there is no evidence of an accessory pathway while achieving complete AV block on adenosine test, the chance of an accessory pathway being present is probably extremely low. Ann Noninvasive Electrocardiol 2011;16(2):180–183     

Development of Rapid Preexcited Ventricular Response to Atrial Fibrillation in a Patient with Intermittent Preexcitation

Intermittent preexcitation during sinus rhythm is indicative of an accessory pathway at a very low risk for sudden death. We present the case of a 49‐year‐old man with intermittent preexcitation who subsequently developed rapid atrial fibrillation with a shortest preexcited R–R interval of 230 milliseconds. Electrophysiology study showed intermittent preexcitation at baseline and 1:1 anterograde accessory pathway conduction to 220 milliseconds in the presence of 1 mcg/min isoproterenol infusion. The pathway was successfully ablated at the lateral mitral annulus. Accessory pathways highly sensitive to catecholamines may show intermittent preexcitation at baseline with potential for rapid conduction during atrial fibrillation and sudden death. (J Cardiovasc Electrophysiol, Vol. 24, pp. 347‐350, March 2013)     

Intermittent Preexcitation and Mesothelioma of the Atrioventricular Node: A Hitherto Undescribed Entity

Mesothelioma of AV Node with WPW. This is the first documented case of spontaneous intermittent preexcitation associated with mesothelioma of the atrioventricular (AV) node. A 66-year-old male with recurrent atrial arrhythmias, palpitations, heart failure, and marked intra-atrial conduction defect that required a pacemaker died during sleep. Electrophysiologic study revealed left free-wall bypass tract with marked intra-atrial conduction defect and prolonged conduction across the bypass tract. With atrial pacing, high degrees of block were noted in the bypass tract. Serial section of the conduction system and both AV rims revealed two left posterior and lateral bypass pathways with patchy areas of fibrosis. A large mesothelioma (benign AV nodal tumor) almost completely replaced the AV node. In addition, there was marked fatty infiltration of the atria. In summary: (1) the intermittent preexcitation with prolonged conduction across the bypass tract and block with atrial pacing were probably related to the incomplete patchy degenerative changes in the bypass tract, and/or almost complete replacement of the AV node by the tumor; (2) the intra-atrial conduction defect was probably related to the replacement of the AV node by mesothelioma and/or the fatty infiltration of the atria: and (3) the paroxysmal atrial arrhythmias probably reflect the marked atrial pathology.     

Preexcitation Secondary to Fasciculoventricular Pathways in Children: A Report of Three Cases

Fasciculoventricular Pathways in Children. Introduction: Fasciculoventricular connections are the rarest form of accessory pathways leading to preexcitation. Electrophysiologic characteristics of these pathways include ventricular preexcitation with normal PR and AH intervals and short HV intervals during sinus rhythm. In addition, atrial overdrive pacing prolongs the PR interval without affecting the HV interval or the degree of preexcitation.
Methods and Results: From March 1994 through February 1997, 3 of 59 pediatric patients referred for electrophysiologic study for preexcitation on surface ECGs were found to have iasciculoventricular pathways. Two patients had no inducible supraventricular tachycardia. One patient had successful ablation of both a left lateral pathway and a concealed antentlateral pathway that had facilitated antidromic and orthodromic supraventricuiar tachycardias, respectively.
Conclusion: Children often manifest minimal preexcitation via accessory AV pathways due to rapid AV conduction and/or left lateral pathway location. Fasciculoventricular pathways may masquerade as Wolff-Parkinson-White syndrome. Separation of the two diagnoses depends on the demonstration of specific electrophysiologic criteria.     

Ablation of right-sided accessory pathways with atrial insertion far from the tricuspid annulus using an electroanatomical mapping system

Ablating Right‐Sided Accessory Pathways With Atrial Insertions Far From Tricuspid Annulus . Background: It is difficult to ablate a right‐sided accessory pathway (AP) with atrial insertion far from the tricuspid annulus (TA). We report our initial experience of ablating this rare AP by a 3‐dimensional electroanatomical mapping system (CARTO). Methods: From January of 2006 to April of 2008, 18 patients with right‐sided APs who failed previous outside ablations were enrolled in this study. Retrograde AP conduction was mapped during pacing at the right ventricular apex by activation‐mapping the right atrium (RA) using a 3‐dimensional electroanatomical mapping system. AP atrial insertion was defined as the earliest retrograde atrial activations and successful ablation of the APs at this site. Results: Among the 18 patients who had failed previous ablation, 10 patients (7 patients with right manifest APs and 3 patients with right conceal APs) had atrial insertions far from the TA. Of the 10 patients, the atrial insertions were found at the base of the RA appendage in 3 patients, at the high lateral RA in 5 patients, at the low lateral RA in other 2 patients. Ablation at the atrial insertions successfully abolished the AP conduction. The mean distance between the atrial insertion sites and the TA was 20.2 ± 2.7 mm. No patients reported recovered AP conduction or recurrent tachycardias after 6‐month follow‐up. Conclusions: The right‐sided APs may have atrial insertion far from the TA. These uncommon variation of APs can be reliably identified and ablated using CARTO system. (J Cardiovasc Electrophysiol, Vol. 22, pp. 499‐505 May 2011)     

预激综合征能改变心室除极全过程

我们曾发现右前间隔旁束可以改变ＱＲＳ终末向量。为了明确这种现象是否具有特异性，我们观察了单旁束患者射频消融前后的常观心电图。结果看到任何区域的旁束普遍存在ＱＲＳ终末波形改变。同时，处在心室除极中间阶段的ＱＲＳ主波亦有极性改变。这些发现证实预激综合征能改变心室除极全过程。其机制可以是直接作用，即旁束引起的激动贯穿于心室除极的始终；也可能是后续影响，即旁束引起的激动未能持续到心室除极结束，但预激既已改变了心室除极的顺序，所产生的时间差不可能立刻消失，引起骨牌效应，继续改变各瞬间向量的综合顺序     

Pregnancy-induced increase of supraventricular arrhythmias in wolff-parkinson-white syndrome

Six women suffering from Wolff-Parkinson-White syndrome and who were previously asymptomatic or nearly asymptomatic, were followed prospectively during and after their subsequent pregnancies. Three women experienced several attacks of supraventricular tachycardia (SVT) for the first time and the rest experienced an increase in their attacks. It seems that there is an increased tendency for SVT in pregnancy. Increased adrenergic sensitivity by estrogens, increased plasma volume, stress, and anxiety during pregnancy may be some of the causative factors.     

Double atrial potentials in left‐sided accessory pathways are associated with paroxysmal atrial fibrillation

1 Introduction

Muscular connections between the coronary sinus (CS) and left atrium probably impact distribution of electrical activity. Double atrial potentials (DP) may be their presentation. The aim was to investigate the presence of DP in CS recordings during atrioventricular reentrant tachycardia (AVRT) and its contribution to the occurrence of paroxysmal atrial fibrillation (AF).

2 Methods

A group of 247 patients with accessory pathways (AP) were screened for DP. The patients with DP during AVRT were compared to those without DP.

3 Results

DP during AVRT were found only among the left‐sided AP (AP‐L). Patients with AP‐L were divided into Group 1 (n  =  17) with DP during AVRT and Group 2 (n  =  108) without DP. Patients in Group 1 had higher incidence of AF in history (47.1% vs. 23.1%; P  =  0.0376), AF induced during electrophysiological (EP) study (70.6% vs. 25%; P  =  0.0002). Group 1 had higher heart rate (HR) during AVRT in the EP study (197.2 ± 27 vs. 175.1 ± 26.3 bpm; P  =  0.0019), but HR of clinical AVRT (208.5 ± 30.8 vs. 191.6 ± 27.8 bpm) was not significant different (P  =  ns). Additionally, electrical alternans of QRS amplitude during AVRT in the EP study was more frequent in Group 1 (52.9 vs. 20.4 %; P  =  0.0048).

4 Conclusion

Patients with DP and AP‐L were more prone to develop AF. The presence of DP was associated with faster AVRT rate. The direction of atrium depolarization during AVRT may be different in the presence of DP and probably plays a role in development of AF in this group of patients.     

The 12‐Lead ECG in Patients with Mahaim Fibers

The aim of this review article is to discuss the electrocardiographic presentation of the so called variants of pre‐excitation (“Mahaim fibers”) during sinus rhythm and tachycardia.     

Familial case of permanent form of junctional reciprocating tachycardia: possible role of the HLA system

The permanent form of junctional reciprocating tachycardia (PJRT) is a very rare arrhythmia with the following clinical and electrocardiographic findings: (1) it occurs predominantly in infants and children; (2) it is almost incessant and refractory to pharmacological therapy; (3) the onset is commonly related to a critical shortening of the P-P cycle length without P-R prolongation; (4) during tachycardia the ECG shows an R-P longer than P-R interval, with a negative P wave in leads II, III, aVF. Recently, the anatomic and electrophysiological characteristics underlying PJRT have been identified: there is an accessory pathway of working myocardium with decremental properties, located in the posterior pyramidal space. A case of familial PJRT is reported: the arrhythmia has been documented in a 72-year-old female and in her 16-year-old grandson. Several triggering tachycardia mechanisms have been observed. Tachycardia was almost incessant and the heart rates were 115 and 135 beats/min, respectively. Typing according to the HLA system, performed in all members of the family, demonstrated the Bw41 antigen in both our patients as well as in the boy's paternal uncle. This is the first documented familial case of PJRT, but the possible significance and correlation with the Bw41 antigen should be further investigated.     

预激综合征心电图PJ间期的分析

目的通过对比分析显性预激综合征患者在射频消融术前后心电图,探讨预激综合征旁路前传对PJ间期的影响。方法选经导管射频消融术治愈的显性预激综合征患者129例,根据旁路部位分为10组。分别测量各组消融前后PR间期、QRS时限、PJ间期,术前δ波时间。比较各组消融前后PJ间期值、术前传导时间(术前PR间期 δ波时间)与术后PR间期大小、术前房室结下传除极心室时间(术前QRS时限-δ波时间)与术后QRS时限长短,比较术前各组间δ波时间长短。结果①右后、右后间隔组术前PJ间期明显短于术后(右后组术前226±18ms,术后236±19ms,p<0.01;右后间隔组术前221±18ms,术后238±31ms,p<0.05),其他部位旁路PJ间期术前与术后比较差异无统计学意义(p>0.05);②房室结下传心室时间与术后PR间期比较,各组差异均无统计学意义(p>0.05);③右后、右后间隔两组术前房室结下传除极心室时间明显短于术后QRS时限(右后组术前79±12ms,术后87±9ms,P=0.01;右后间隔组术前70±13ms,术后86±9ms,p<0.05),其他8组术前房室结下传除极心室时间与术后QRS时限比较差异无统计学意义(p>0.05);④右后、右后间隔组δ波时间明显长于左后、左后间隔组(p<0.05)。结论预激综合征不仅不延长PJ间期,且可能缩短PJ间期,其主要取决于旁路心室端距离心室正常最后除极部位的远近及心室预激程度。     

Nodoventricular Pathway Associated With Twin AV Nodes: Complexity of Ablation in Single Ventricle Physiology

Nodoventricular Pathway. We report the case of a patient with heterotaxy syndrome including complex single ventricular morphology and interrupted IVC in association with twin conduction systems and a nodoventricular accessory pathway connection. The presence of 3 distinct QRS morphologies was inadvertently discovered during a hemodynamic catheterization study and prompted formal EP testing prior to hepatic venous inclusion into the Fontan circuit and loss of access to the atrial chamber for testing and therapy. This patient underscores the importance of close surveillance and high index of suspicion of arrhythmia mechanisms in patients with heterotaxy syndrome in conjunction with single ventricle morphology. (J Cardiovasc Electrophysiol, Vol. 21, pp. 936‐939, August 2010)