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Int J Clin Exp Med 2015;8(8):14520-14526 www.ijcem.com /ISSN:1940-5901/IJCEM0008425 Original Article Clinical observations of supraventricular arrhythmias in patients with brugada syndrome Bing Liu, Chengjun Guo, Dongping Fang, Jinping Guo Department of Cardiology, Beijng Anzhen Hospital, Capital University of Medical Sciences, Beijing, China Received March 25, 2015; Accepted June 4, 2015; Epub August 15, 2015; Published August 30, 2015 Abstract: Objective: To study various types of supraventricular arrhythmias in patients with Brugada Syndrome. Methods: Forty six patients with ECG of spontaneous type Brugada and with ventricular and/or supraventricular tachyarrhythmia, without structural heart diseases which were excluded by echocardiography, underwent 24 hHolter recording, electrophysiological study and/or radiofrequency ablation. Results: There were thirty-nine male and seven female (mean age 37.44 years) among total forty-six patients. Twenty one patients had family histories of tachycardia, twentythree patients experienced episodes of syncope, and three patients were resuscitated from cardiac arrest. One patient had ventricular fibrillation and third degree atrioventricular block, eleven patients had polymorphic ventricular tachycardia and five patients had monomorphic ventricular tachycardia. Fourteen patients had atrial tachyarrhythmia, paroxysmal supraventricular tachycardia was found in five patients including four WolfParkinson-White syndrome, two patients hadventricular tachycardia and third degree atrioventricular block, one of them had atrial fibrillation, two patients had both supraventricular tachycardia and ventricular tachycardia, three patients had both atrial tachyarrhythmia and supraventricular tachycardia, two third degree atrioventricular block patients had atrial flutter, one patienthad both atrial tachyrhythmia and ventricular tachycardia. Radiofrequency blation was performed in thirty-nine patients and succeed in thirty-two, four patients were implanted with pacemakers, and four patients had implantable cardioverter defibrillators. Conclusion: In addition to ventricular tachycardia and ventricular fibrillation, patients with Brugada syndrome exhibit various supraventricular tachyarrhythmia and third degree atrioventricular block. In patients with Brugada syndrome, the dysfunction of the cardiac ion channel, which related to mutation of cardiac sodium channelgene, is not limited in His Purkinje system and ventricular myocardium, but also in the atrium and atrioventricular node, which may serves as a cause of dispersion of repolarization and phase 2 reentry leading to various arrhythmias. Keywords: Brugada syndrome, cardiac arrhythmia, conduction abnormality, atrioventricular block, supraventricular tachyarrhythmia Introduction Brugada syndrome (BS) is an autosomal dominant genetic disease characterized by dometyped or saddle-shaped ST segment elevation in V1~V3 leads, with diagram in V1 lead resemblingthat of right bundle branch block [1, 2]. Patients suffer from paroxysmal palpitations, syncope, or ventricular fibrillation (VF) which leads to sudden unexplained nocturnaldeath [3]. The current study found that BSis associated with dysfunction of the sodium channel caused by mutation of the SCN5A gene which encodes α subunit of cardiac sodium channel [4]. Since BS is causedby mutation of cardiac sodium channel gene, then the sodium channel dysfunction should not be limited to ventricular muscle, other parts of the myocardium should also have this problem which will trigger a variety of arrhythmias. Current studies focuses mostly on the mechanism of BS complicated ventricular tachycardia (VT) and ventricular fibrillation, not many reports on supraventricular arrhythmia. Here we reported the clinical observation results of 46 cases of BS patients complicated with various types of arrhythmias. Materials and methods Patients who visited our hospital between March 1998 to March 2007 suffering from heart palpitations, syncope and nocturnal dys- Supraventricular arrhythmias of brugada syndromepatients Table 1. Clinical characteristics of patients with Brugada Syndrome Clinical characteristics Number of cases Total number of patients 46 Male 39 Female 7 History of illness Palpitation 43 Syncope 23 Cardiopulmonary resuscitation 3 Family history 21 Treatments Electrophysiology exam + RFA 35 Electrophysiology exam + RFA + pace maker 3 Electrophysiology exam + ICD 3 Electrophysiology exam + RFA + ICD 1 Electrophysiology exam 1 Pace maker 1 Follow-up 2 Follow-up time (5.25±2.37) years who could afford the cost. In this study, the term supraventricular arrhythmia means atrial arrhythmia or arrhythmia caused by atrioventricular bypass and dual atrioventricular node pathways, and paroxysmal supraventricular tachycardia (PSVT) means supraventricular tachycardiacaused by atrioventricular bypass and dual atrioventricular node pathways. Results Total forty-six cases who met the BS diagnostic criteria were treated during the nine-year periods as above mentioned, with thirty-nine males and seven females, and ages ranging from twelve to sixty-six years old (37.44 ± 14.52). Twenty-one cases have a family history, and twenty-three cases have history of syncope, including three cases undergoing cardiopulmonary resuscitation (Table Note: ICD=implantable cardioverter defibrillators; RFA=radiofrequency 1). Among the total forty-six cases, there ablation. arefive cases complicated with paroxysmal supraventricular tachycardia (PSVT, pnea were selected for routine ECG study. If with four cases of dominant WPW syndrome, found to have ST segment elevationin leads Figure 1); two cases of PSVT coexisting withVT; V1~V3, excluded organic heart disease and electhree cases of PSVT coexisting with atrial flutter trolyte imbalance by physical examina(AFL); fourteen cases of atrial tachycardia (AT) tion, blood biochemical tests, echocardiogracoexisting withAFL and atrial fibrillation (AF); phy and coronary angiography, diagnosed with two cases of AT coexisting with third-degree the “Expert Consensus Recommendations” atrioventricular block; one case of AT coexisting about BS diagnosis and treatment revised in with VT; eleven cases of polymorphic VT; five2005 as a diagnostic criterion [5]. Spontaneous cases of monomorphic VT; one case of ventrictype I Brugada syndrome was diagnosed directular fibrillation (VF) electrical storm coexisting ly by the combination of ECG changes with hiswith third-degree atrioventricular block; onetory of illness and familyhistory; Type II and case of VT coexisting withthird-degree atriovenIIIBrugada syndrome was diagnosed with initial tricular block; one case of VTcoexisting with ECG with induced ECG changes in the precorthird degree atrioventricular block and AF. dial leads inPropafenone stimulation test; There are total ten cases (21.74%, Table 2) Induced type I Brugada syndrome was diagcoexisting withPSVT (with/without other types nosed with the combination of ECG changes of arrthymia) among the forty-six BS cases, six with history of illness and family history. For all of which wereconfirmed as paroxysmal atrioBS patients, routine ECG and Holter were perventricular reentrant tachycardia (AVRT, formed to observe the types of arrhythmia, and 13.04%), and the rest fourwere confirmed as for some patients,conventional electrophysiolparoxysmal atrioventricular nodal reentrant ogy and radiofrequency ablation were pertachycardia (AVNRT, 8.70%. Figure 2 by electroformed following the protocol described in the physiological examination. There are twentyliterature [6]. Permanent cardiac pacemakers two cases concurrent with rapid atrial arrhythwere implanted in patient with symptomatic mia (47.83%, Figure 3), including eighteen third-degree atrioventricular block, and implantcases of atrial flutter and atrial fibrillation able cardioverter defibrillators (ICD) were (39.13%, Figure 4), seventeen cases of which implanted in patients with cardiac arrest and were treated with radiofrequency ablation with 14521 Int J Clin Exp Med 2015;8(8):14520-14526 Supraventricular arrhythmias of brugada syndromepatients Figure 1. ECG in a patient with Brugada syndrome coexisting within intermittent WPW syndrome. Patient is a 37-yearold male, with arrows indicating the oblique ST segment in V1lead, and ST segment elevation in V2leads inversely down during pre-excitation. Table 2. Clinical characteristics of PSVT in patients with Brugada syndrome ID Age/gender Palpitation Syncope CPR Family history Arrthymia SVT type/VT and AF origin 1 2 3 4 5 6 7 8 9 10 34/F 59/M 45/M 42/M 48/M 47/F 37/F 42/M 25/M 36/M + + + + + + + + + + + + - - + + + - PSVT PSVT/AF PSVT/VT PSVT/AF PSVT/AFL PSVT PSVT/VT PSVT PSVT PSVT AVRT AVNRT/PV AVNRT/RVOT AVNRT/PV LAVRT AVNRT AVRT/RT, His B. AVRT AVRT AVRT Treatment/followup (years) RFA/4 RFA/7 RFA/4.5 RFA/7 RFA/7 RFA/3.5 RFA/4 RFA/5 RFA/4.5 RFA/5 Note: F=female; M=male; AFL=Atrial flutter; AF=Atrial fibrillation; RFA=radiofrequencyablation; AVRT=atrioventricular reentrant tachycardia; AVNRT=atrioventricular nodal reentrant tachycardia; RVOT=Right ventricular outflow tract; RV=Right ventricle; PV=Pulmonary vein; PSVT=paroxysmal supraventricular tachycardia; VT=Ventricular tachycardia; CPR=Cardiopulmonary resuscitation; His B.=His bundle. success in eleven cases, and three cases had recurrence of the arrhythmia during follow-ups. There are five cases concurrent with threedegree atrioventricular block (10.87%). There are twenty-two cases (47.83%) concurrent with rapid ventricular arrhythmias (with or without 14522 other types ofarrhythmia). There are different degrees ofintraventricular block in all forty-six cases. Thirty-nine cases underwent radiofrequency ablation with success in thirty-two cases, four cases were implanted with implantable cardiac pacemakers, one case underwent Int J Clin Exp Med 2015;8(8):14520-14526 Supraventricular arrhythmias of brugada syndromepatients Figure 2. ECG in a patient with Brugada syndrome coexisting withatrioventricular nodal reentrant tachycardia.Patient is a 42-year-old male, with sinus rhythm (left) and atrioventricular nodal reentrant tachycardia at onset (Right). Figure 3. ECG in a patient with Brugada syndrome coexisting withatrial tachycardia. Patient is 36-year-old male. 14523 Int J Clin Exp Med 2015;8(8):14520-14526 Supraventricular arrhythmias of brugada syndromepatients Figure 4. ECG in a patient with Brugada syndrome coexisting withatrial flutter. Patient is a 50-year-old male. electrophysiological examination alone, and four cases were implanted with ICDs. There is one case of paroxysmal atrial tachycardia showing concurrence of BS and short QT syndrome (SQTS) (Figure 5). Discussion Clinically, BS usually coexists with malignant ventricular arrhythmias, with sudden cardiac death as the initial presentation in some cases, and has become the focus of clinical studies recently. In our study, among total forty-six BS cases, there are thirty-two cases complicated by rapid atrial arrhythmia and/orparoxysmal supraventricular tachycardia and atrioventricular block, few such studies have been reported in the literature. Our data confirm that, besides ventricular tachycardia and ventricular fibrillation, BS patients can also be complicated by non-ventricular arrhythmias, including atrial flutter and atrial fibrillation (39.13%), AVRT (13.04%) and AVNRT (8.70%). Two or more types of arrhythmias can coexist. In 1999, Anzelevitchet al reported only 10% of BS patients were compli- 14524 cated with paroxysmal atrial fibrillation, but recent studies have shown that the concurrence rate can be as high as 39%, which is similar to the results inour study [7]. The present studies suggest that the mechanism of arrhythmia in BS patients is dysfunction of the sodium channel in the cell membranecaused by gene mutation, such as accelerated inactivation or decelerated reactivation, which results in loss of the action potential (AP) dome. This loss is, however, heterogeneous, generating epicardial dispersion of repolarization. This dispersion creates a vulnerable window, which allows phase 2 reentry to cause a premature impulse, which triggers VT/VF based on reentry between transmural layers [8, 9]. Since BS is caused by mutation of the cardiac sodium channelgene, then the above mentioned mechanisms of increase of repolarization dispersion and reentry can also existin atrial and atrioventricular node cells, which perhaps help to explain the pathogenesis of atrial tachy-arrhythmias and AVNRT in BS patients [10]. Increases in tension of Vagus nerve and hemodynamic changes caused by supraven- Int J Clin Exp Med 2015;8(8):14520-14526 Supraventricular arrhythmias of brugada syndromepatients tricular tachy-arrhythmias can be inducing factors forventricular tachycardia and ventricular fibrillation in BS patients. The mechanism for concurrence of BS with AVRT is currently unknown [11], and it is suggested that electrophysiological examination and drug provocation test should be performed in WPW syndrome patients with history of sudden death in order to detect BS. In our study, there areforty-six cases (100%) coexisting with intraventricular block, and five cases coexisting with third degree atrioventricular block, indicating that conduction delays exist in atrium, atrioventricular junction and ventricle, and conduction delay may be associated with tachy-arrhythmias, which provides a new idea for pathogenesis of concurrent tachyarrhythmia in BS patients. Figure 5. ECG in a patient with Brugada syndrome coexisting with short QT syndrome. Patient is a 19-year-old male. A. Standard lead ECG. The heart rate is 85 beats/min, QT interval is 280 mS, with ST segment almost completely lost, and high and sharp symmetrical T waves on the right chest leads. B. Dynamic ECG showing atrial tachycardia. 14525 There are few studies published for non-ventricular arrhythmias in BS patients, thus it is possible that a large number of concurrent supraventricular arrhythmias in BS patients have long been neglected. In clinical, in addition to ventricular tachy-arrhythmias, nonventricular arrhythmias such as atrial flutter, atrial fibrillation, AVNRT or even AVRT and third degree atrioventricular block should also be considered as reasons to cause palpitations and syncope in BS patients. In BS patients with syncope likely caused by Int J Clin Exp Med 2015;8(8):14520-14526 Supraventricular arrhythmias of brugada syndromepatients supraventricular tachy-arrhythmia, atrial stimulation should be performed during electrophysiological examination to induce such arrhythmia. Incases of BS concurrent with supraventricular tachycardia, radiofrequency ablation should be the preferred treatment; the use of IC antiarrhythmic drugsshould be avoided. In BS patients with syncope, an ICD with supraventricular tachycardia recognition function should be chosen to avoid false discharge [12]. Studies have found that BS can coexist with SQTS suggesting that BS is possibly a polygenic disease. The currently known three causative genes for SQTS, KCNH2, KCNQ1 and KCNJ2 can all encode cardiac potassium channels [13], the abnormalities of which can causeshortening of QT interval. But BS and SQTS coexistence case was not found in our study. [5] [6] [7] Disclosure of conflict of interest None. Address correspondence to: Chengjun Guo, Department of Cardiology, Beijng Anzhen Hospital, Capital University of Medical Sciences, No.2, Anzhen Road, Chaoyang District, Beijing 100029, China. Tel: 86-010-64456132; E-mail: guochengjun@medmail. com.cn References [1] [2] [3] [4] Brugada P and Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. 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