Figure-8 tachycardia confined to the anterior wall of the left atrium

Incisional atrial tachycardias have been described most frequently in patients with previous corrective surgery for congenital heart defects and mitral valve disease. Less information is available on atrial tachycardias appearing late after isolated aortic valve surgery. We report the case of a patient who developed a left figure-8 tachycardia after undergoing aortic valve replacement. During electrophysiologic study the entire cycle length of the tachycardia was mapped within a low voltage area confined to the left anterior atrial wall. However, during ablation a transmural lesion could not be attained. The mapping and ablation strategy along with the mechanism of the tachycardia are discussed.     

Clinical and electrophysiologic variants of false ventricular tachycardia (supraventricular tachycardia with wide QRS complex)

Electrophysiological abnormalities of the heart conduction system and their role in development of different forms of supraventricular tachycardias, are discussed. Electrophysiological mechanisms and diagnostic criteria of the supraventricular tachycardias with wide QRS complex, are described.     

Sex-Based Differences in Cardiac Arrhythmias, ICD Utilisation and Cardiac Resynchronisation Therapy

Many important differences in the presentation and clinical course of cardiac arrhythmias are present between men and women that should be accounted for in clinical practice. In this paper, we review published data on gender differences in cardiac excitable properties, supraventricular tachycardias, ventricular tachycardias, sudden cardiac death, and the utilisation of implantable defibrillators and cardiac resynchronisation therapy. Women have a higher heart rate at rest, and a longer QT interval than men. They further have a narrower QRS complex and lower QRS voltages on the 12-lead ECG with more often non-specific repolarisation abnormalities at rest. Supraventricular tachycardias, such as AV nodal reentrant tachycardia, are twice as frequent in women compared with men. Atrial fibrillation, however, has a 1.5-fold higher prevalence in men. The triggers for idiopathic right ventricular outflow tract tachycardia (VT) initiation are gender specific, i.e. hormonal changes play an important role in the occurrence of these VTs in women. There are clear-cut gender differences in acquired and congenital LQTS. Brugada syndrome affects men more commonly and severely than women. Sudden cardiac death is less prevalent in women at all ages and occurs 10 years later in women than in men. This may be related to the later onset of clinically manifest coronary heart disease in women. Among patients who receive ICDs and CRT devices, women appear to be under-represented, while they may benefit even more from these novel therapies.     

兔右室流出道室速对L型钙通道α1c蛋白表达的影响

目的：通过建立右室流出道室速（RVOT-VT）的动物模型,以L型钙通道α1c蛋白作为观察指标,观察RVOT-VT时对L型钙通道α1c蛋白表达的影响,旨在探讨L型钙通道在RVOT-VT中的作用。方法：健康新西兰大耳白兔30只,随机分三组,分别为对照组（10只）、室速组（10只）、室速加维拉帕米干预组（10只）。采用免疫组织化学的方法对三组实验动物的右室流出道心肌组织进行L型钙通道cdc蛋白表达的检测。结果：1、高频刺激主动脉与肺动脉交界处均诱发了起源于右室流出道部位的室速,且室速持续时间均大于4小时。2、室速组L型钙通道α1c蛋白表达量明显下降;干预组L型钙通道α1cc蛋白的表达下降,但与对照组比较无显著差异。结论：1、室速组的心肌L型钙通道α1c蛋白表达发生了重构。2、维拉帕米可以改善心肌L型钙通道α1c蛋白的重构。3、L型钙通道在RVOT-VT发生、持续中起重要作用。     

An uncommon case of spontaneous conversion from AV re-entry tachycardia to AV nodal re-entry tachycardia in a patient with dual tachycardia

We report the case of a 46-year old patient in whom an electrophysiology study (EP) was performed due to paroxysmal supraventricular tachycardia documented in 12-lead ECG. During the EP study, supraventricular tachycardia was induced easily and it corresponded to orthodromic AV reentry tachycardia (AVRT) using a concealed left free wall accessory pathway. However, during the study AVRT spontaneously and repeatedly converted to the typical slow-fast AV node reentry tachycardia (AVNRT). Both accessory and AV nodal slow pathways were ablated, due to the finding that both AVRT and AVNRT were independently inducible during the EP study.     

Verapamil Sensitive Ventricular Tachycardia Associated With A Cardiac Hemangioma In The Right Ventricular Outflow Tract

Primary tumors of the heart are rare, but they are often associated with refractory arrhythmias. Vascular tumors of the heart comprise a small minority of primary cardiac tumors. In patients with structurally normal hearts, ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) can be sensitive to adenosine, vagal maneuvers, and calcium channel blockers. In this report, we describe a case of ventricular tachycardia originating from within a hemangioma in the RVOT that was ultimately controlled with verapamil.     

Different Effects of Adrenergic Beta-receptor Blockade on Heart Rate Response to Mental Stress,Catecholamines, and Exercise

The magnitude and duration of effect of a single 40-mg oral tablet of oxprenolol on the tachycardias associated with motor-car driving, isoprenaline infusion, and walking were compared against placebo in six normal people by a double-blind study. The tachycardias due to driving and isoprenaline were both conspicuousy reduced for over eight hours; the magnitude and duration of the reduction in exercise tachycardia was substantially less. Thus relatively small doses of beta-receptor antagonists will suppress the increase in heart rate induced by mental stress or catecholamines with relatively little effect on the response to everyday exercise. Possibly smaller doses of these drugs would relieve emotionally-induced anginal pain and tachycardia.     

Simultaneous Accessory Pathway and AV Node Mechanical Block

We report a clinical case of a 22-year-old female referred to our institution due to palpitations and preexcitation. Her ECG suggested a right superior paraseptal accessory pathway (AP), which was localised during the electrophysiological study at the superior paraseptal region in close proximity to the His recordings. Reproducible orthodromic reciprocating tachycardia was induced by atrial pacing with extrastimuli. Cryo-mapping performed in the area of earliest atrial activation was not able to terminate the tachycardia. A second attempt, slightly more posterior, caused mechanical block of the AP, which rendered the tachycardia non-inducible. More pressure with the ablation catheter determined a Wenckebach type supra-hisian AV block, which was transient but reproducible. Given this finding no ablation was done. Simultaneous block to the AP and the atrioventricular node has rarely been reported using radiofrequency energy. However, to our knowledge this phenomenon has not been previously reported in large series using cryo-thermal energy.     

The value of Holter monitoring in the assessment of Pediatric patients

Aims

Holter monitoring (HM) has been established as one of the most effective noninvasive clinical tools in the diagnosis, assessment and risk stratification of cardiac patients. However, studies in the pediatric age group are limited. The present work aims at determining the value of HM in the diagnosis and management of children.

Settings and Design

Retrospective study conducted at a tertiary referral arrhythmolology service.

Methods and Material

Holter records of 1319 pediatric patients (54.1% males and 45.9% females) were reviewed. Their average age was 6.7± 4.1 years (5 days-16 years). Indications for which Holter monitoring was done were analysed as well as all the abnormalities diagnosed and factors that may increase Holter yield.

Statistical analysis used

Statistical Package of social science (SPSS) version 9,0 was used for analysis of data.

Results

The most common indications were palpitations (19.8%), syncope (17.8%), cardiomyopathy (12.6%), chest pain (10%), evaluation of antiarrhythmic therapy (6.8%), postoperative assessment (2.6%) and complete AV Block (2.4%). A sum of 141 Holter recordings were found abnormal with a total diagnostic yield of 10.7%. The highest contribution to diagnosis was in postoperative assessment (32.4%) and in cardiomyopathy (19.9%) where the most common abnormalities were frequent supraventricular / ventricular premature beats, supraventricular tachycardia, ventricular tachycardia and AV block. Diagnostic yield was low in patients with palpitations (5.7%) and syncope (0.4%). An abnormal ECG was significantly associated with a higher diagnostic yield (p=0.0001). None of the children with chest pain had abnormal Holter recordings.

Conclusions

HM has an extremely valuable role in the assessment of high risk patients (postoperative and cardiomyopathy). However in children with palpitations, syncope and chest pain HM has a low yield. In this group of patients an abnormal ECG is more likely to be associated with abnormal Holter recordings.     

Chronobiology of Symptomatic Supraventricular Paroxysmal Tachycardia

The circadian, circaseptenal and circaannual occurrence of supraventricular paroxysmal tachycardias (SVPT) were examined in patients addressing an Emergency Department. Sixty-one patients, 22 men and 39 women aged 48.3+13.0 y, were eligible and investigated during a solar year. Cosinor method indicated a significant circadian SVPT variation, with an acrophase at about 6 p.m. A similar periodicity was also detected in supraventricular premature beat prevalence (acrophase at 3 h 31 min), concordant with heart rate peaking. Monday was the most frequently affected day, while the circa-annual analysis disclosed a peak in summer and autumn. Our findings provide further evidence that SVPT shows the highest occurrence during daytime, in possible connection with adrenergic influence. Moreover there are clues that cyclic stressors, e.g. the ones connected with working-activity resumption or climate influence, may partly condition SVPT appearance during the week or the year.     

Chronobiology of Symptomatic Supraventricular Paroxysmal Tachycardia

The circadian, circaseptenal and circaannual occurrence of supraventricular paroxysmal tachycardias (SVPT) were examined in patients addressing an Emergency Department. Sixty-one patients, 22 men and 39 women aged 48.3+13.0 y, were eligible and investigated during a solar year. Cosinor method indicated a significant circadian SVPT variation, with an acrophase at about 6 p.m. A similar periodicity was also detected in supraventricular premature beat prevalence (acrophase at 3 h 31 min), concordant with heart rate peaking. Monday was the most frequently affected day, while the circa-annual analysis disclosed a peak in summer and autumn. Our findings provide further evidence that SVPT shows the highest occurrence during daytime, in possible connection with adrenergic influence. Moreover there are clues that cyclic stressors, e.g. the ones connected with working-activity resumption or climate influence, may partly condition SVPT appearance during the week or the year.     

Dynamic Conduction and Repolarisation Changes in Early Arrhythmogenic Right Ventricular Cardiomyopathy versus Benign Outflow Tract Ectopy Demonstrated by High Density Mapping & Paced Surface ECG Analysis

Aims

The concealed phase of arrhythmogenic right ventricular cardiomyopathy (ARVC) may initially manifest electrophysiologically. No studies have examined dynamic conduction/repolarization kinetics to distinguish benign right ventricular outflow tract ectopy (RVOT ectopy) from ARVC''s early phase. We investigated dynamic endocardial electrophysiological changes that differentiate early ARVC disease expression from RVOT ectopy.

Methods

22 ARVC (12 definite based upon family history and mutation carrier status, 10 probable) patients without right ventricular structural anomalies underwent high-density non-contact mapping of the right ventricle. These were compared to data from 14 RVOT ectopy and 12 patients with supraventricular tachycardias and normal hearts. Endocardial & surface ECG conduction and repolarization parameters were assessed during a standard S₁-S₂ restitution protocol.

Results

Definite ARVC without RV structural disease could not be clearly distinguished from RVOT ectopy during sinus rhythm or during steady state pacing. Delay in Activation Times at coupling intervals just above the ventricular effective refractory period (VERP) increased in definite ARVC (43±20 ms) more than RVOT ectopy patients (36±14 ms, p = 0.03) or Normals (25±16 ms, p = 0.008) and a progressive separation of the repolarisation time curves between groups existed. Repolarization time increases in the RVOT were also greatest in ARVC (definite ARVC: 18±20 ms; RVOT ectopy: 5±14, Normal: 1±18, p<0.05). Surface ECG correlates of these intracardiac measurements demonstrated an increase of greater than 48 ms in stimulus to surface ECG J-point pre-ERP versus steady state, with an 88% specificity and 68% sensitivity in distinguishing definite ARVC from the other groups. This technique could not distinguish patients with genetic predisposition to ARVC only (probable ARVC) from controls.

Conclusions

Significant changes in dynamic conduction and repolarization are apparent in early ARVC before detectable RV structural abnormalities, and were present to a lesser degree in probable ARVC patients. Investigation of dynamic electrophysiological parameters may be useful to identify concealed ARVC in patients without disease pedigrees by using endocardial electrogram or paced ECG parameters.     

Coexistence of atrioventricular nodal reentrant tachycardia and idiopathic left ventricular outflow-tract tachycardia

Double tachycardia is a relatively rare condition. We describe a 21 year old woman with history of frequent palpitations. In one of these episodes, she had wide complex tachycardia with right bundle branch and inferior axis morphology. A typical atrioventricular nodal tachycardia was induced during electrophysiologic study, aimed at induction of clinically documented tachycardia. Initially no ventricular tachycardia was inducible. After successful ablation of slow pathway, a wide complex tachycardia was induced by programmed stimulation from right ventricular outflow tract. Mapping localized the focus of tachycardia in left ventricular outflow tract and successfully ablated via retrograde aortic approach. During 7 month's follow-up, she has been symptom free with no recurrence. This work describes successful ablation of rare combination of typical atrioventricular nodal tachycardia and left ventricular outflow tract tachycardia in the same patient during one session.     

Calcium dysregulation increases right ventricular outflow tract arrhythmogenesis in rabbit model of chronic kidney disease

Chronic kidney disease (CKD) increases the risk of arrhythmia. The right ventricular outflow tract (RVOT) is a crucial site of ventricular tachycardia (VT) origination. We hypothesize that CKD increases RVOT arrhythmogenesis through its effects on calcium dysregulation. We analysed measurements obtained using conventional microelectrodes, patch clamp, confocal microscopy, western blotting, immunohistochemical examination and lipid peroxidation for both control and CKD (induced by 150 mg/kg neomycin and 500 mg/kg cefazolin daily) rabbit RVOT tissues or cardiomyocytes. The RVOT of CKD rabbits exhibited a short action potential duration, high incidence of tachypacing (20 Hz)-induced sustained VT, and long duration of isoproterenol and tachypacing-induced sustained and non-sustained VT. Tachypacing-induced sustained and non-sustained VT in isoproterenol-treated CKD RVOT tissues were attenuated by KB-R7943 and partially inhibited by KN93 and H89. The CKD RVOT myocytes had high levels of phosphorylated CaMKII and PKA, and an increased expression of tyrosine hydroxylase-positive neural density. The CKD RVOT myocytes exhibited large levels of I_to, I_Kr, NCX and L-type calcium currents, calcium leak and malondialdehyde but low sodium current, SERCA2a activity and SR calcium content. The RVOT in CKD with oxidative stress and autonomic neuron hyperactivity exhibited calcium handling abnormalities, which contributed to the induction of VT.     

ICD discrimination of SVT versus VT with 1:1 V-A conduction: A review of the literature

Inappropriate ICD shocks are associated with increased mortality. They also impair patients'' quality of life, increase hospitalizations, and raise health-care costs. Nearly 80% of inappropriate ICD shocks are caused by supraventricular tachycardia. Here we report the case of a patient who received a single-lead dual-chamber sensing ICD for primary prevention of sudden cardiac death and experienced inappropriate ICD shocks. V-A time, electrogram morphology, and response to antitachycardia pacing suggested atrioventricular nodal reentry tachycardia, which was confirmed in an electrophysiology study. Inspired by this case, we performed a literature review to discuss mechanisms for discrimination of supraventricular tachycardia with 1:1 A:V relationship from ventricular tachycardia with 1:1 retrograde conduction.     

Fast and slow narrow complex tachycardia in one patient: two of a kind?

A 35-year-old female was referred to our hospital. For more than ten years, she had had complaints of two types of paroxysmal palpitations, both with a sudden onset. The first type was rapid and often accompanied by light-headedness; the second she described as much less rapid, better tolerated, and often terminated by the Valsalva manoeuvre. The incidence and duration of both types of paroxysms were increasing. In the emergency room of the referring hospital, the tachycardia was terminated with intravenous verapamil.The electrophysiological study revealed normal conduction parameters. Premature atrial beats (due to catheter manipulation) or delivered atrial extra stimuli over a wide range easily induced two types of tachycardia.AV node modification by radiofrequency ablation using the posterior approach was performed. With this approach, RF ablation of the caudal extension of the AV node is performed, which modifies the slow pathway, so that the reentrant circuit is interrupted. After this intervention, no tachycardia whatsoever could be induced and during followup (8 months), no recurrent arrhythmia of any kind occurred.     

Measure twice, cut once: pitfalls in the diagnosis of supraventricular tachycardia

In atrioventricular nodal and atrioventricular reentrant tachycardia, the relative timing of atrial and ventricular activation may sometimes be very similar, even during electrophysiological studies, and this may lead to an erroneous diagnosis and inappropriate treatment. As examples, we describe two cases that were recently referred to our hospital for a second opinion and treatment of paroxysmal supraventricular tachycardia. In both, the original diagnosis of the referring centres was commontype atrioventricular nodal reentrant tachycardia. Catheter ablation in those centres was unsuccessful. During our electrophysiological studies, however, an atrioventricular reentrant tachycardia was demonstrated, using a concealed accessory pathway for retrograde conduction in both patients. The accessory atrioventricular connection was successfully ablated and on follow-up both patients remained free of symptoms without medication. These findings illustrate the importance of complete electrophysiological analysis even for apparently simple supraventricular arrhythmias. (Neth Heart J 2010;18:78–84.)     

小儿阵发性室上性心动过速37 例临床分析

目的:对比研究和评价不同方法治疗小儿阵发性室上性心动过速(PSVT)的的疗效,提高转复率。方法:回顾性分析2002.04-2011.05我院住院治疗的37例PSVT患儿的临床资料,并分析比较心律平与胺碘酮的药物转复率,构成比采用x2检验,α=0.05。结果:37例患儿中,13例治疗原发病后自动转率,24例患儿给予心律平治疗,其中1例放弃治疗,5例未见效,心律平转复率为69.77%,5例未见效患儿改用胺碘酮治疗,1例死于原发病,1例控制症状后行射频消融术治愈,胺碘酮转复率为75%,二者之间无显著差异性。结论:心律平与胺碘酮均能较好的治疗小儿PSVT,对于反复发作,药物治疗无效的小儿PSVT,射频消融术已成为最佳选择。     

Tissue tracking imaging for identifying the origin of idiopathic ventricular arrhythmias: a new role of cardiac ultrasound in electrophysiology

Several strategies for mapping ventricular outflow tract tachycardia have been reported as useful indices for differentiating between those originating from the right and the left side. Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an ultrasonographic technique that measures the myocardial motion amplitude towards the transducer in each region during systole, identifying regional myocardial displacement on the basis of myocardial velocities using color Doppler myocardial imaging principles. In this technique, the origin of the arrhythmia could be recognized as the site where the earliest color-coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary studies this modality was found to be useful in differentiating outflow tract ventricular tachycardias. ECCS was always found below or at the level of the pulmonary valve in all arrhythmias which could be ablated from the right ventricular outflow tract, while in those where the ECCS was above and close to the pulmonary valve it could be ablated from the left sinus of valsalva. These results indicate that TTI can provide detailed and accurate information on the arrhythmia origin of outflow tract tachycardia and may be useful for differentiating between an outflow tract tachycardia originating from the LV epicardium remote from the LSV and that from the LSV. Newer advances in echocardiographic technologies like high resolution, high frame rate real time three dimensional echocardiography with speckle tracking may further improve the precise localization of arrhythmias in the future.     

Coronary sinus norepinephrine concentrations during ventricular tachycardia induced by left stellate ganglion stimulation in dogs

Coronary sinus catecholamine overflow was measured in open-chest dogs, anesthetized with sodium thiopental and alpha-chloralose, during left sympathetic stimulation. Uniform ventricular tachycardias were induced in 9 out of 16 dogs during either left stellate ganglion or left ventrolateral cardiac nerve stimulations. Significant increases in norepinephrine (8.1 ng/mL, plasma) and epinephrine (0.19 ng/mL, plasma) overflows were obtained after 30 and 90 s of stimulation, respectively. Maximum norepinephrine overflow was significantly higher in dogs with ventricular tachycardia than in those without it (16.0 vs. 7.4 ng/mL, p less than 0.05). This suggests that the induction of ventricular tachycardia in the normal myocardium is related to the amount of local secretion of norepinephrine during nerve stimulation.