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Trohman RG. Etiologies, Mechanisms, Management, and Outcomes of Electrical Storm. J Intensive Care Med 2024; 39:99-117. [PMID: 37731333 DOI: 10.1177/08850666231192050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Electrical storm (ES) is characterized by three or more discrete sustained ventricular tachyarrhythmia episodes occurring within a limited time frame (generally ≤ 24 h) or an incessant ventricular tachyarrhythmia lasting > 12 h. In patients with an implantable cardioverterdefibrillator (ICD), ES is defined as three or more appropriate device therapies, separated from each other by at least 5 min, which occur within a 24-h period. ES may constitute a medical emergency, depending on the number arrhythmic episodes, their duration, the type, and the cycle length of the ventricular arrhythmias, as well as the underlying ventricular function. This narrative review was facilitated by a search of MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other clinically relevant studies. The search was limited to English-language reports published between 1999 and 2023. ES was searched using the terms mechanisms, genetics, channelopathies, management, pharmacological therapy, sedation, neuraxial modulation, cardiac sympathetic denervation, ICDs, and structural heart disease. Google and Google scholar as well as bibliographies of identified articles were reviewed for additional references. This manuscript examines the current strategies available to treat ES and compares pharmacological and invasive treatment strategies to diminish ES recurrence, morbidity, and mortality.
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Affiliation(s)
- Richard G Trohman
- Section of Electrophysiology, Division of Cardiology, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, USA
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Gupta N, Talathi S, Kalantre S. Syncope in a 3-year-old male: A case report. World J Emerg Med 2020; 11:188-190. [PMID: 32351654 DOI: 10.5847/wjem.j.1920-8642.2020.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Neha Gupta
- Department of Pediatrics, Lincoln Medical Center, Bronx, New York, USA
| | - Saurabh Talathi
- Department of Pediatrics, Lincoln Medical Center, Bronx, New York, USA
| | - Sarika Kalantre
- Department of Pediatrics, Lincoln Medical Center, Bronx, New York, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Children's Hospital at Montefiore and Albert Einstein College of Medicine, Bronx, New York, USA
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Autodetection of J Wave Based on Random Forest with Synchrosqueezed Wavelet Transform. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1315357. [PMID: 30057906 PMCID: PMC6051278 DOI: 10.1155/2018/1315357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/28/2018] [Indexed: 11/18/2022]
Abstract
J wave is the bulge generated in the descending slope of the terminal portion of the QRS complex in the electrocardiogram. The presence of J wave may lead to sudden death. However, the diagnosis of J wave variation only depends on doctor’s clinical experiences at present and missed diagnosis is easy to occur. In this paper, a new method is proposed to realize the automatic detection of J wave. First, the synchrosqueezed wavelet transform is used to obtain the precise time-frequency information of the ECG. Then, the inverse transformation of SST is computed to get the intrinsic mode function of the ECG. At last, the time-frequency features and SST-based and the entropy features based on modes are fed to Random forest to realize the automatic detection of J wave. As the experimental results shown, the proposed method has achieved the highest accuracy, sensitivity, and specificity compared with existing techniques.
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Abstract
Brugada syndrome (BrS) is a cardiac disease caused by an inherited ion channelopathy associated with a propensity to develop ventricular fibrillation. Implantable cardioverter defibrillator implantation is recommended in BrS, based on the clinical presentation in the presence of diagnostic ECG criteria. Implantable cardioverter defibrillator implantation is not always indicated or sufficient in BrS, and is associated with a high device complication rate. Pharmacological therapy aimed at rebalancing the membrane action potential can prevent arrhythmogenesis in BrS. Quinidine, a class 1A antiarrhythmic drug with significant Ito blocking properties, is the most extensively used drug for the prevention of arrhythmias in BrS. The present review provides contemporary data gathered on all drugs effective in the therapy of BrS, and on ineffective or contraindicated antiarrhythmic drugs.
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Key Words
- Brugada syndrome,
- arrhythmia,
- bepridil,
- cilostazol,
- denopamine,
- disopyramide,
- isoproterenol,
- orciprenaline,
- pharmacology,
- quinidine,
- quinine
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Affiliation(s)
- Oholi Tovia Brodie
- University of Miami Miller School of Medicine Miami, USA.,Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University Tel-Aviv, Israel
| | - Yoav Michowitz
- Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University Tel-Aviv, Israel
| | - Bernard Belhassen
- Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University Tel-Aviv, Israel
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Abstract
A healthy 28-year-old man presented with multiple brief episodes of convulsion. He was found to have ventricular fibrillation which required defibrillation in the emergency department. After exclusion of organic heart diseases, Brugada syndrome was diagnosed and required implantable cardioverter defibrillator (ICD) implantation. The case emphasized the recognition of malignant cardiac dysrrhythmias as a cause for seizures. The management in the emergency department was discussed.
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Abstract
More than 20 years have passed since the description of Brugada syndrome as a clinical entity. The original case series depicted patients who all had coved ST-segment elevation in the right precordial leads, associated with a high risk of sudden death and no apparent structural heart disease. As subsequent registry data were published, it became apparent that the spectrum of risk is wide, with the majority of patients classified as low risk. Two consensus documents have been published that will continue to be updated. Despite intense research efforts, many controversies still exist over its pathophysiology and the risk stratification for sudden death. Management continues to be challenging with a lack of drug therapy and high complication rates from implantable cardioverter defibrillators. In this review, we highlight the current state-of-the-art therapies and their controversies.
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Affiliation(s)
- Anthony Li
- Cardiovascular Sciences Research Centre, St George's University of London, Cranmer Terrace, London, SW17 0RE, UK
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Ercan S, Oylumlu M, Altunbas G, Davutoglu V. An Iatrogenically Unmasked Life Threatening Disease: Brugada Syndrome. Korean Circ J 2013; 43:426-8. [PMID: 23882294 PMCID: PMC3717428 DOI: 10.4070/kcj.2013.43.6.426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/11/2012] [Accepted: 08/10/2012] [Indexed: 11/11/2022] Open
Abstract
Brugada syndrome is a life threatening disease that is usually overlooked during emergency service admissions. It is characterized by typical electrocardiography resembling right bundle branch block, static or dynamic ST-segment elevation in leads V 1-3. There is familial tendency in some cases. A majority of patients have a structurally normal heart and are likely to remain asymptomatic, however they may present to emergency departments with syncope and various serious arrhythmias. Therefore it is crucially important for emergency medicine physicians not to omit this potential diagnosis. Herein we report a case with Brugada syndrome which was iatrogenically unmasked after propafenone administration for atrial fibrillation.
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Affiliation(s)
- Suleyman Ercan
- Department of Cardiology, Gaziantep University School of Medicine, Gaziantep, Turkey
| | - Muhammed Oylumlu
- Department of Cardiology, Şehitkamil State Hospital, Gaziantep, Turkey
| | - Gokhan Altunbas
- Department of Cardiology, Kilis State Hospital, Kilis, Turkey
| | - Vedat Davutoglu
- Department of Cardiology, Gaziantep University School of Medicine, Gaziantep, Turkey
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Abstract
Two decades ago, a series of 8 idiopathic ventricular fibrillation patients who each had an abnormal ECG (right bundle branch block with coved-type ECG), but otherwise had normal hearts were described by Brugada and Brugada. Since then, the clinical entity has become known as Brugada syndrome (BS). Shortly thereafter, mutations of the SCN5A gene that encodes for the α-subunit of the sodium channel were found, galvanizing the field of ion channelopathies following in the footsteps of the breakthrough in long QT syndrome. Over the past 20 years, extensive research in this field has produced major progress toward better understanding of BS and the gaining of knowledge of the genetic background, pathophysiology and new management. Two consensus reports were published to help define the diagnostic criteria, risk stratification and management of BS patients. However, there are controversies. In this review, we will share our experiences of BS patients in Thailand and discuss advances in many aspects of the syndrome (ie, genetics and pathophysiology) and some of these pertinent controversies, as well as new treatment of the syndrome with catheter ablation.
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Affiliation(s)
- Gumpanart Veerakul
- Cardiovascular Research and Prevention Center, Bhumibol Adulyadej Hospital and Pacific Rim Electrophysiology Research, Bangkok, Thailand
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Shimizu A. Is this a philosophic issue? Do patients with drug-induced Brugada type ECG have poor prognosis? (Pro). Circ J 2010; 74:2455-63. [PMID: 20962432 DOI: 10.1253/circj.cj-10-0747] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Brugada syndrome (BS) has an intermittent or concealed type, which can be unmasked by the sodium (Na(+))-channel-blocker challenge test. The appropriate risk stratification of patients with a drug-induced Brugada-type electrocardiographic (ECG), especially those without a history of syncope or aborted sudden cardiac death, remains unclear. The prognosis of patients with BS depends on the clinical type, cardiac arrest, syncope or if asymptomatic. The ratio of the asymptomatic group varies from 56.9% to 63.6% and, furthermore, their annual cardiac event rate is relatively lower at 0.24-3.6% compared with the cardiac arrest group. Patients with a drug-induced Brugada-type ECG have a poor prognosis if they had a history of ventricular fibrillation (VF) or aborted sudden cardiac death, because their risk becomes similar to that of patients with spontaneous Brugada-type ECG. They have the disturbance of the Na(+)-channel and the electrophysiologic substrate of VF, proven by the high inducibility of VF by stimulation test even in patients without spontaneous VF. Spontaneous VF will never occur if there is no VF substrate. Implantable cardioverter-defibrillators will certainly protect them, so patients with a drug-induced Brugada-type ECG, even without a history of VF or aborted sudden cardiac death, should be considered to have a poor prognosis.
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Affiliation(s)
- Akihiko Shimizu
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Minami Kogushi, Ube, Japan.
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Hedley PL, Jørgensen P, Schlamowitz S, Moolman-Smook J, Kanters JK, Corfield VA, Christiansen M. The genetic basis of Brugada syndrome: a mutation update. Hum Mutat 2009; 30:1256-66. [PMID: 19606473 DOI: 10.1002/humu.21066] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Brugada syndrome (BrS) is a condition characterized by a distinct ST-segment elevation in the right precordial leads of the electrocardiogram and, clinically, by an increased risk of cardiac arrhythmia and sudden death. The condition predominantly exhibits an autosomal dominant pattern of inheritance with an average prevalence of 5:10,000 worldwide. Currently, more than 100 mutations in seven genes have been associated with BrS. Loss-of-function mutations in SCN5A, which encodes the alpha-subunit of the Na(v)1.5 sodium ion channel conducting the depolarizing I(Na) current, causes 15-20% of BrS cases. A few mutations have been described in GPD1L, which encodes glycerol-3-phosphate dehydrogenase-1 like protein; CACNA1C, which encodes the alpha-subunit of the Ca(v)1.2 ion channel conducting the depolarizing I(L,Ca) current; CACNB2, which encodes the stimulating beta2-subunit of the Ca(v)1.2 ion channel; SCN1B and SCN3B, which, in the heart, encodes beta-subunits of the Na(v)1.5 sodium ion channel, and KCNE3, which encodes the ancillary inhibitory beta-subunit of several potassium channels including the Kv4.3 ion channel conducting the repolarizing potassium I(to) current. BrS exhibits variable expressivity, reduced penetrance, and "mixed phenotypes," where families contain members with BrS as well as long QT syndrome, atrial fibrillation, short QT syndrome, conduction disease, or structural heart disease, have also been described.
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Affiliation(s)
- Paula L Hedley
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
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Delpón E, Cordeiro JM, Núñez L, Thomsen PEB, Guerchicoff A, Pollevick GD, Wu Y, Kanters JK, Larsen CT, Hofman-Bang J, Burashnikov E, Christiansen M, Antzelevitch C. Functional effects of KCNE3 mutation and its role in the development of Brugada syndrome. Circ Arrhythm Electrophysiol 2009; 1:209-18. [PMID: 19122847 DOI: 10.1161/circep.107.748103] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION The Brugada Syndrome (BrS), an inherited syndrome associated with a high incidence of sudden cardiac arrest, has been linked to mutations in four different genes leading to a loss of function in sodium and calcium channel activity. Although the transient outward current (I(to)) is thought to play a prominent role in the expression of the syndrome, mutations in I(to)-related genes have not been identified as yet. METHODS AND RESULTS One hundred and five probands with BrS were screened for ion channel gene mutations using single strand conformation polymorphism (SSCP) electrophoresis and direct sequencing. A missense mutation (R99H) in KCNE3 (MiRP2) was detected in one proband. The R99H mutation was found 4/4 phenotype positive and 0/3 phenotype-negative family members. Chinese hamster ovary (CHO)-K1 cells were co-transfected using wild-type (WT) or mutant KCNE3 and either WT KCND3 or KCNQ1. Whole-cell patch clamp studies were performed after 48 hours. Interactions between Kv4.3 and KCNE3 were analyzed in co-immunoprecipitation experiments in human atrial samples. Co-transfection of R99H-KCNE3 with KCNQ1 produced no alteration in current magnitude or kinetics. However, co-transfection of R99H KCNE3 with KCND3 resulted in a significant increase in the I(to) intensity compared to WT KCNE3+KCND3. Using tissues isolated from left atrial appendages of human hearts, we also demonstrate that K(v)4.3 and KCNE3 can be co-immunoprecipitated. CONCLUSIONS These results provide definitive evidence for a functional role of KCNE3 in the modulation of I(to) in the human heart and suggest that mutations in KCNE3 can underlie the development of BrS.
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Affiliation(s)
- Eva Delpón
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain
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Shimeno K, Takagi M, Maeda K, Tatsumi H, Doi A, Nakagawa E, Yoshiyama M. A predictor of positive drug provocation testing in individuals with saddle-back type ST-segment elevation. Circ J 2009; 73:1836-40. [PMID: 19734691 DOI: 10.1253/circj.cj-09-0296] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND A drug provocation test is performed to unmask a type 1 electrocardiogram (ECG) in individuals with saddle-back type ST-segment elevation in the right precordial leads (SB-ECG). The study investigated predictors of positive responders (PR) by drug testing. METHODS AND RESULTS A total of 58 consecutive individuals with SB-ECG in lead V2 were enrolled and drug testing was performed. In leads V2 at standard and the third intercostal space (V2(IC3)), the QRS duration was measured, the amplitudes of r' wave (r'), ST-segment 20 and 40 ms after the r' wave (r'20 and r'40, respectively), the bottom of the ST-segment (ST(b)), the differences between r' and r'20 (r'-r'20), r' and r'40 (r'-r'40), r' and ST(b) (r'-ST(b)), and the descending rate of the ST-segment [(r'-r'20)/r'; DR20, (r'-r'20)/(r'-ST(b)); DR20-ST(b)] were also measured. Thirty-five PR had significantly longer QRS duration, larger r'20 and r'40, and smaller r'-r'20, DR20, and DR20-ST(b) than negative responders. DR20 and DR20-ST(b) in leads V2 and V2(IC3) were most significantly different between 2 groups. The positive and negative predictive values of ;DR20-ST(b) in lead V2(IC3) <0.62' for prediction of positive tests were 92.3% and 81.8%, respectively. CONCLUSIONS In individuals with SB-ECG, DR20 and DR20-ST(b) in leads V2 and V2(IC3) might be useful predictors of positive testing.
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Affiliation(s)
- Kenji Shimeno
- Department of Internal Medicine and Cardiology, Osaka City University Graduate School of Medicine, Japan
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Immunohistochemical marker for Na+ CP type Valpha (C-20) and heterozygous nonsense SCN5A mutation W822X in a sudden cardiac death induced by mild anaphylactic reaction. Appl Immunohistochem Mol Morphol 2009; 17:357-62. [PMID: 19318916 DOI: 10.1097/pai.0b013e3181955b37] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A sudden death likely due to mild anaphylactic reaction in a young man is described. Autoptic, histologic, immunohistochemical, and laboratory findings were strongly consistent with the diagnosis of a mild anaphylactic reaction. Genetic molecular analysis, performed on formalin-fixed, paraffin-embedded tissues, showed a mutation described as W822X in a family with electrocardiographic pattern typical of Brugada Syndrome. It results in a nonsense mutation generating a truncated form of the channel protein. The mutation is due to a point substitution of a guanine with an adenine residue (G2466A). Immunohistochemistry and laser scanning confocal microscopy on sections from heart formalin-fixed, paraffin-embedded tissues led us to confirm the cellular localization of the Na+ CP type Valpha (C-20) at the intercalated disks of ventricular myocytes and nearly 50% reduction in Na+ channels expression in ventricular myocytes when compared with control cases. We suggest that the anaphylactic reaction that occurred in the young man could serve as a trigger mechanism, responsible for his sudden death with a SCN5A mutation associated with the Brugada syndrome.
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Viskin S, Rosso R, Márquez MF, Antzelevitch C. The acquired Brugada syndrome and the paradox of choice. Heart Rhythm 2009; 6:1342-4. [PMID: 19716090 DOI: 10.1016/j.hrthm.2009.07.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2009] [Indexed: 12/15/2022]
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Nakagawa E, Takagi M, Tatsumi H, Yoshiyama M. Successful radiofrequency catheter ablation for electrical storm of ventricular fibrillation in a patient with Brugada syndrome. Circ J 2008; 72:1025-9. [PMID: 18503235 DOI: 10.1253/circj.72.1025] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The case of a 41-year-old man with Brugada syndrome (BS) who suffered electrical storms (ES) of ventricular fibrillation (VF) is presented. Although intravenous infusion of isoproterenol (ISP) suppressed the VF occurrence, he consistently experienced recurrence of VF following discontinuation of ISP infusion. Quinidine and cilostazol were ineffective. An analysis of VF episodes on electrocardiogram monitoring revealed that the QRS morphology of the first beat of all VF episodes was identical to that of premature ventricular complexes (PVCs) with a left bundle branch-block morphology and inferior axis, which occurred repetitively before the episodes of VF and were recorded throughout the day. In addition, stored electrograms from the implantable cardioverter defibrillator showed that the first beat of all VF episodes had the same morphology. On electrophysiological study, the VF-triggering PVC was found to originate from the posterior portion of the right ventricular outflow tract area and their elimination, which was achieved with radiofrequency catheter ablation (RFCA), resulted in the suppression of ES. Although several other PVCs were still observed, the patient has been free of VF during the 29-month follow-up period. This case indicates that RFCA of VF-triggering PVCs may be useful in the treatment of drug-resistant ES in patients with BS.
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Affiliation(s)
- Eiichiro Nakagawa
- Department of Internal Medicine and Cardiology, Osaka City University Medical School, Osaka, Japan
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Clancy CE, Wehrens XHT. Mutation-specific effects of lidocaine in Brugada syndrome. Int J Cardiol 2007; 121:249-52. [PMID: 17761312 DOI: 10.1016/j.ijcard.2007.05.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 05/19/2007] [Indexed: 12/31/2022]
Abstract
Brugada syndrome (BrS) is a hereditary cardiac disease characterized by right bundle-branch block, an elevation of the ST-segment in leads V1 through V3 on the electrocardiogram, and ventricular fibrillation that can lead to sudden cardiac death. Mutations in the cardiac sodium channel gene SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent Na+ channel (Na(v)1.5), are identified in 15-30% of patients with BrS. Most SCN5A mutations lead to a 'loss-of-function' phenotype, reducing the Na+ current during the early phases of the action potential. Anti-arrhythmic drugs that affect Na+ channels typically block these Na+ channels, thereby exaggerating the ECG abnormalities and arrhythmogenicity in the BrS. However, the N406S mutation in SCN5A causes distinct gating defects and enhanced intermediate inactivation of Na+ channels, which led to unexpected pharmacological effects of lidocaine in a patient carrying this mutation. In the presence of the N406S mutation, use-dependent block by lidocaine is reduced and recovery from intermediate inactivation is hastened by lidocaine. These findings suggest that lidocaine may improve the Brugada phenotype in patients with N406S by increasing the availability of Na+ channels.
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Koopmann TT, Beekman L, Alders M, Meregalli PG, Mannens MMAM, Moorman AFM, Wilde AAM, Bezzina CR. Exclusion of multiple candidate genes and large genomic rearrangements in SCN5A in a Dutch Brugada syndrome cohort. Heart Rhythm 2007; 4:752-5. [PMID: 17556197 DOI: 10.1016/j.hrthm.2007.02.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Accepted: 02/27/2007] [Indexed: 11/28/2022]
Abstract
BACKGROUND The Brugada syndrome is an inherited cardiac electrical disorder associated with a high incidence of life-threatening arrhythmias. Screening for mutations in the cardiac Na+ channel-encoding gene SCN5A uncovers a mutation in approximately 20% of Brugada syndrome cases. Genetic heterogeneity and/or undetected SCN5A mutations, such as exon duplications and deletions, could be involved in the remaining 80% mutation-negative patients. OBJECTIVES Thirty-eight SCN5A mutation-negative Dutch Brugada syndrome probands were studied. The SCN5A gene was investigated for exon duplication and deletion, and a number of candidate genes (Caveolin-3, Irx-3, Irx-4, Irx-5, Irx-6, Plakoglobin, Plakophilin-2, SCN1B, SCN2B, SCN3B, and SCN4B) were tested for the occurrence of point mutations and small insertions/deletions. METHODS We used a quantitative multiplex approach to determine SCN5A exon copy numbers. Mutation analysis of the candidate genes was performed by direct sequencing of polymerase chain reaction-amplified coding regions. RESULTS No large genomic rearrangements in SCN5A were identified. No mutations were found in the candidate genes. Twenty novel polymorphisms were identified in these genes. CONCLUSION Large genomic rearrangements in SCN5A are not a common cause of Brugada syndrome. Similarly, the studied candidate genes are unlikely to be major causal genes of Brugada syndrome. Further studies are required to identify other genes responsible for this syndrome.
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Affiliation(s)
- Tamara T Koopmann
- Center for Heart Failure Research, Experimental and Molecular Cardiology Group, University of Amsterdam, Amsterdam, The Netherlands
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Ueyama T, Shimizu A, Yamagata T, Esato M, Ohmura M, Yoshiga Y, Kanemoto M, Kametani R, Sawa A, Suzuki S, Sugi N, Matsuzaki M. Different Effect of the Pure Na+ Channel-Blocker Pilsicainide on the ST-Segment Response in the Right Precordial Leads in Patients With Normal Left Ventricular Function. Circ J 2007; 71:57-62. [PMID: 17186979 DOI: 10.1253/circj.71.57] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The response of the ST-segment in the right precordial leads to Na+ channel blockers in patients without structural heart disease and a typical Brugada-type ECG has not been fully elucidated. METHODS AND RESULTS A pilsicainide challenge test was performed in 161 patients and according to recently established ECG criteria and an organized computer algorithm, the ST morphology was classified and the maximum increase in the J wave amplitude (maxDeltaJ) from the standard and high right precordial leads V1-3 was examined. Before the test, subjects exhibiting type 1 ECG in the standard leads were excluded. After administering pilsicainide, type 1 ECGs in the standard leads were observed in 31 cases and a maxDeltaJ of >or=200 microV was observed in 29 cases (23 type 1, 2 type 2/3 and 4 normal ECGs). In the additional higher right precordial leads, type 1 ECGs were observed in 55 cases and a maxDeltaJ of >or=200 microV was observed in 45 cases (42 type 1 and 3 type 2/3 ECGs). CONCLUSIONS A maxDeltaJ>or=200 microV induced by pilsicainide, including that measured in the high right precordial leads, was associated with a change mainly to a type 1 ECG.
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Affiliation(s)
- Takeshi Ueyama
- Division of Cardiovascular Medicine, Department of Medical Bioregulation, Yamaguchi University Graduate School of Medicine, Hofu, Japan.
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Herbert E, Chahine M. Clinical aspects and physiopathology of Brugada syndrome: review of current concepts. Can J Physiol Pharmacol 2006; 84:795-802. [PMID: 17111025 DOI: 10.1139/y06-038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brugada syndrome (BS) is an inherited cardiac disorder characterized by typical electrocardiographic patterns of ST segment elevation in the precordial leads, right bundle branch block, fast polymorphic ventricular tachycardia in patients without any structural heart disease, and a high risk of sudden cardiac death. The incidence of BS is high in male vs. female (i.e., 8–10/1: male/female). The disorder is caused by mutations in the SCN5A gene encoding Nav1.5, the cardiac sodium channel, which is the only gene in which mutations were found to cause the disease. Mutations in SCN5A associated with the BS phenotype usually result in a loss of channel function by a reduction in Na+ currents. We review the clinical aspects, risk stratification, and therapeutic management of this important syndrome.
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Affiliation(s)
- E Herbert
- Research Centre, Laval Hospital and Department of Medicine, Laval University, Sainte-Foy, Quebec G1V 4G5, Canada
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Mizusawa Y, Sakurada H, Nishizaki M, Hiraoka M. Effects of low-dose quinidine on ventricular tachyarrhythmias in patients with Brugada syndrome: low-dose quinidine therapy as an adjunctive treatment. J Cardiovasc Pharmacol 2006; 47:359-64. [PMID: 16633076 DOI: 10.1097/01.fjc.0000206437.27854.65] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Quinidine is suggested as an effective agent to suppress ventricular fibrillation (VF) in the Brugada syndrome by inhibiting transient outward K(+) current (Ito) leading to the reduction and abbreviation of the disparity of repolarization in the right ventricular outflow region and ST segment elevation in the right precordial leads of electrocardiogram. We sought to assess the efficacy of low-dose (300-600 mg) quinidine sulfate on the prevention of ventricular fibrillation induction by programmed electrical stimulation (PES) and spontaneous ventricular fibrillation episodes during the subsequent follow-up period. Electrophysiologic study was performed in 14 patients with the Brugada syndrome (14 men, mean age 50 +/- 11 years, range 32-75) before and during the treatment with low-dose quinidine and evaluated the efficacy of the drug therapy. Ventricular fibrillation was induced in all the patients by programmed electrical stimulation at baseline. After oral quinidine administration (300 mg or 600 mg/d), programmed electrical stimulation was repeated. Ventricular fibrillation induction was prevented in 6 of 14 patients (44%). Serum quinidine concentration was higher in the patients with suppressed VF induction than those without (1.88 +/- 0.44 versus 1.31 +/- 0.43 microg/ml, respectively). After programmed electrical stimulation, 9 of 14 patients (64%), in whom four had implantable cardioverter defibrillator implantation, continued to receive quinidine. During a mean follow-up period of 31 months on quinidine, no side effects except one with diarrhea were observed (12.5%). There were no ventricular fibrillation recurrences in 3 of the 9 patients, who had frequent implantable cardioverter defibrillator discharges due to ventricular fibrillation attacks before treatment with quinidine. Low-dose quinidine has a potential as an adjunctive therapy for patients of the Brugada syndrome with frequent implantable cardioverter defibrillator discharges.
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Affiliation(s)
- Yuka Mizusawa
- Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, Shibuya-ku, Japan.
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MacKinnon MA. Brugada syndrome: silent assassin. Air Med J 2006; 25:124-6. [PMID: 16679254 DOI: 10.1016/j.amj.2006.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
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Sassone B, Saccà S, Donateo M. Paradoxical effect of ajmaline in a patient with Brugada syndrome. ACTA ACUST UNITED AC 2006; 8:251-4. [PMID: 16627450 DOI: 10.1093/europace/euj045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AIMS The typical Brugada ECG pattern consists of a prominent J-wave associated with ST-segment elevation localized in the right precordial leads V1-V3. In many patients, the ECG presents periods of transient normalization and the Brugada-phenotype can be unmasked by the administration of class-I antiarrhythmics. Reports have documented the heterogeneity of the Brugada syndrome ECG-phenotype characterized by unusual localization of the ECG abnormalities in the inferior leads. Case report A 51-year-old man, without detectable structural heart disease, was referred to us because of a history of syncope, dizziness, and palpitations. The ECG showed a J-wave and ST-segment elevation in the right precordial leads, suggesting Brugada syndrome. As other causes of the ECG abnormalities were excluded, the patient underwent an electrophysiological study that documented easy induction of ventricular fibrillation. During infusion of ajmaline, new prominent J-waves and ST-segment elevation appeared in the inferior leads, whereas the basal ECG abnormalities in the right precordial leads normalized. After infusion of isoprenaline, the ECG-pattern resumed the typical Brugada pattern. An implantable cardioverter-defibrillator was recommended. CONCLUSION In our patient, the double localization of the typical Brugada-pattern and the paradoxical effect of ajmaline on the ECG abnormalities confirmed the possibility of a phenotype heterogeneity in the Brugada syndrome.
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Affiliation(s)
- Biagio Sassone
- Section of Arrhythmology, Division of Cardiology, Ospedale di Bentivoglio (BO), Unità Operativa di Cardiologia, via Marconi 35, 40010 Bentivoglio, Italy.
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Towbin JA, Vatta M, Wang Z, Bowles NE, Li H. Emerging targets in the long QT syndromes and Brugada syndrome. ACTA ACUST UNITED AC 2005. [DOI: 10.1517/14728222.3.3.423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Antzelevitch C, Brugada P, Borggrefe M, Brugada J, Brugada R, Corrado D, Gussak I, LeMarec H, Nademanee K, Perez Riera AR, Shimizu W, Schulze-Bahr E, Tan H, Wilde A. Brugada syndrome: report of the second consensus conference: endorsed by the Heart Rhythm Society and the European Heart Rhythm Association. Circulation 2005; 111:659-70. [PMID: 15655131 DOI: 10.1161/01.cir.0000152479.54298.51] [Citation(s) in RCA: 1167] [Impact Index Per Article: 61.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since its introduction as a clinical entity in 1992, the Brugada syndrome has progressed from being a rare disease to one that is second only to automobile accidents as a cause of death among young adults in some countries. Electrocardiographically characterized by a distinct ST-segment elevation in the right precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young and otherwise healthy adults, and less frequently in infants and children. Patients with a spontaneously appearing Brugada ECG have a high risk for sudden arrhythmic death secondary to ventricular tachycardia/fibrillation. The ECG manifestations of Brugada syndrome are often dynamic or concealed and may be unmasked or modulated by sodium channel blockers, a febrile state, vagotonic agents, alpha-adrenergic agonists, beta-adrenergic blockers, tricyclic or tetracyclic antidepressants, a combination of glucose and insulin, hypo- and hyperkalemia, hypercalcemia, and alcohol and cocaine toxicity. In recent years, an exponential rise in the number of reported cases and a striking proliferation of articles defining the clinical, genetic, cellular, ionic, and molecular aspects of the disease have occurred. The report of the first consensus conference, published in 2002, focused on diagnostic criteria. The present report, which emanated from the second consensus conference held in September 2003, elaborates further on the diagnostic criteria and examines risk stratification schemes and device and pharmacological approaches to therapy on the basis of the available clinical and basic science data.
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Abstract
Since its introduction as a new clinical entity in 1992, the Brugada syndrome has attracted great interest because of its high incidence in many parts of the world and its association with high risk for sudden death in infants, children, and young adults. Recent years have witnessed an exponential rise in the number of reported cases and a striking proliferation of articles serving to define the clinical, genetic, cellular, ionic, and molecular aspects of the disease. A consensus report published in 2002 delineated diagnostic criteria for the syndrome. A second consensus conference was held in September 2003. This review provides an in-depth overview of the clinical, genetic, molecular, and cellular aspects of the Brugada syndrome, incorporating the results of the two consensus conferences, and the numerous clinical and basic publications on the subject. The proposed terminology, diagnostic criteria, risk stratification schemes, and device and pharmacologic approach to therapy discussed are based on available clinical and basic studies and should be considered a work-in-progress that will without doubt require fine-tuning as confirmatory data from molecular studies and prospective trials become available.
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Abstract
This article outlines the up-to-date understanding of the molecular basis of disorders that cause sudden death. Several arrhythmic disorders that cause sudden death have been well-described at the molecular level, including the long QT syndromes and Brugada syndrome; this article reviews the current scientific knowledge of these diseases. Hypertrophic cardiomyopathy, a myocardial disorder that causes sudden death also has been well-studied. Finally, a disorder in which myocardial abnormalities and rhythm abnormalities coexist, arrhythmogenic right ventricular dysplasia, is described.
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MESH Headings
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/physiopathology
- Arrhythmogenic Right Ventricular Dysplasia/genetics
- Arrhythmogenic Right Ventricular Dysplasia/physiopathology
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Child
- Death, Sudden, Cardiac/etiology
- ERG1 Potassium Channel
- Ether-A-Go-Go Potassium Channels
- Humans
- KCNQ Potassium Channels
- KCNQ1 Potassium Channel
- Long QT Syndrome/complications
- Long QT Syndrome/genetics
- Long QT Syndrome/therapy
- NAV1.5 Voltage-Gated Sodium Channel
- Potassium Channels/physiology
- Potassium Channels, Voltage-Gated
- Sodium Channels/physiology
- Syndrome
- Tachycardia, Ventricular/genetics
- Wolff-Parkinson-White Syndrome/physiopathology
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Affiliation(s)
- Jeffrey A Towbin
- Department of Pediatrics (Cardiology), Texas Children's Hospital and Baylor College of Medicine, 6621 Fannin Street, FC. 430.09, Houston, TX 77030, USA.
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Abstract
BACKGROUND Automatic implantable cardioverter-defibrillator therapy is considered the only effective treatment for high-risk patients with Brugada syndrome. Quinidine depresses I(to) current, which may play an important role in the arrhythmogenesis of this disease. METHODS AND RESULTS The effects of quinidine bisulfate (mean dose, 1483+/-240 mg) on the prevention of inducible and spontaneous ventricular fibrillation (VF) were prospectively evaluated in 25 patients (24 men, 1 woman; age, 19 to 80 years) with Brugada syndrome. There were 15 symptomatic patients (including 7 cardiac arrest survivors and 7 patients with unexplained syncope) and 10 asymptomatic patients. All 25 patients had inducible VF at baseline electrophysiological study. Quinidine prevented VF induction in 22 of the 25 patients (88%). After a follow-up period of 6 months to 22.2 years, all patients are alive. Nineteen patients were treated with quinidine for 6 to 219 months (mean+/-SD, 56+/-67 months). None had an arrhythmic event, although 2 had non-arrhythmia-related syncope. Administration of quinidine was associated with a 36% incidence of side effects that resolved after drug discontinuation. CONCLUSIONS Quinidine effectively prevents VF induction in patients with Brugada syndrome. Our data suggest that quinidine also suppresses spontaneous arrhythmias and could prove to be a safe alternative to automatic implantable cardioverter-defibrillator therapy for a substantial proportion of patients with Brugada syndrome. Randomized studies comparing these two therapies seem warranted.
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Affiliation(s)
- Bernard Belhassen
- Department of Cardiology, Tel-Aviv Sourasky Medical Center, and Tel-Aviv University, Sackler School of Medicine, Weizman St 6, Tel-Aviv 64239 Israel.
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Park DW, Nam GB, Rhee KS, Han GH, Choi KJ, Kim YH. Clinical characteristics of Brugada syndrome in a Korean population. Circ J 2004; 67:934-9. [PMID: 14578600 DOI: 10.1253/circj.67.934] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of this study was to investigate the clinical features of Korean patients with Brugada syndrome (BS). Between June 1998 and April 2002, 15 consecutive patients with BS (13 men, 2 women; mean age, 44+/-10 years) were identified. Eight patients had experienced at least 1 episode of aborted sudden death, 5 patients had had an episode of syncope or chest pain, and 2 patients were asymptomatic at diagnosis. The electrocardiographics (ECGs) of all patients showed spontaneous ST-segment elevation in leads V(1-3) at baseline and 13 patients (87%) showed transient normalization of the ST-segment elevation during follow-up. Twelve patients received an implantable cardioverter-defibrillator (6 patients with aborted sudden death, 5 patients with syncope or chest pain, 1 asymptomatic patient). During a mean follow-up of 19+/-14 months, arrhythmic events occurred in 5 of the 6 patients with aborted sudden death and in 1 of the 5 patients with syncope or chest pain. None of the asymptomatic patients developed any symptoms suggestive of an arrhythmic event. The clinical and ECG manifestation of BS in Korean patients is diverse, but the dynamic nature of the ST segment provides an important clue to the diagnosis of BS. Recurrence of malignant arrhythmia is extremely high in those patients who initially present with aborted sudden death.
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Affiliation(s)
- Duk-Woo Park
- Department of Internal Medicine, Ulsan University, College of Medicine, Seoul, Korea
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Fish JM, Antzelevitch C. Cellular and ionic basis for the sex-related difference in the manifestation of the Brugada syndrome and progressive conduction disease phenotypes. J Electrocardiol 2004; 36 Suppl:173-9. [PMID: 14716629 DOI: 10.1016/j.jelectrocard.2003.09.054] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
UNLABELLED The Brugada syndrome (BS) has been linked to mutations in SCN5A. Despite equal hereditary transmission of the mutation between the sexes, the syndrome is 8 to 10 times more likely to occur in males. As recently reported, SCN5A mutations such as G1406R lead to development of BS phenotype principally in males and conduction disease phenotype in females. We hypothesized that these differences may be related to a larger transient outward current (Ito)-mediated right ventricular (RV) epicardial (Epi) action potential (AP) notch in males versus females, resulting in a higher incidence of all-or-none repolarization at the end of phase 1 and phase 2 re-entry (P2R) when challenged with sodium and calcium channel block. Using canine RV wedge preparations, we developed an experimental model of the BS using terfenadine to depress the AP dome in RV Epi. RESULTS RV Epi AP phase 1 amplitude corrected to phase 2 amplitude was 12% smaller in males (n=18) compared to females (n=8, P<.05) at a cycle length of 2,000 ms. When exposed to 5 microM terfenadine for up to 2 hours, 6 of 7 male but only 2 of 7 female preparations exhibited spontaneous P2R, generating a closely coupled extrasystole. Two of 6 male and 1 of 2 female preparations displaying P2R developed polymorphic VT/VF. Female and male preparations that failed to develop P2R displayed progressive conduction impairment with continued exposure to terfenadine and developed polymorphic and monomorphic VT/VF when paced at rapid rates. Male preparations pretreated with 4-aminopyridine to inhibit Ito displayed progressive conduction impairment but not Brugada syndrome. CONCLUSION Our data suggest that the presence of a more prominent Ito-mediated notch in the Epi of males predisposes males to the development of the Brugada phenotype and that a smaller Epi notch in females relegates them to development of progressive conduction problems under conditions in which inward currents are compromised.
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Affiliation(s)
- Jeffrey M Fish
- Masonic Medical Research Laboratory, Utica, NY 13501-1787, USA
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Priori SG, Napolitano C, Vicentini A. Inherited arrhythmia syndromes: applying the molecular biology and genetic to the clinical management. J Interv Card Electrophysiol 2004; 9:93-101. [PMID: 14574020 DOI: 10.1023/a:1026255617913] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thanks to the contribution of molecular genetics, the genetic bases, the pathogenesis and genotype-phenotype correlation of diseases such as the Long QT syndrome, the Brugada Syndrome, the Progressive cardiac conduction defect (Lenegre disease), the Catecholaminergic Polymorphic Ventricular Tachycardia and Andersen Syndrome have been progressively unveiled and show an extremely high degree of genetic heterogeneity. The evidences supporting this concept are outlined with a particular emphasis on the growing complexity of the molecular pathways that may lead to arrhythmias and sudden death, in term of the relationships between genetic defect(s) and genotype(s) as well as gene-to gene interactions. The current knowledge is reviewed, focusing on the evidence that a single clinical phenotype may be caused by different genetic substrates and, conversely, a single gene may cause very different phenotypes acting through different pathways.
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Affiliation(s)
- Silvia G Priori
- Molecular Cardiology, IRCCS Fondazione S Maugeri, University of Pavia, Via Ferrata 8, 27100 Pavia, Italy.
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Abstract
Computational models of the electrical and mechanical function of the heart are reviewed. These models attempt to explain the integrated function of the heart in terms of ventricular anatomy, the structure and material properties of myocardial tissue, the membrane ion channels, and calcium handling and myofilament mechanics of cardiac myocytes. The models have established the computational framework for linking the structure and function of cardiac cells and tissue to the integrated behavior of the intact heart, but many more aspects of physiological function, including metabolic and signal transduction pathways, need to be included before significant progress can be made in understanding many disease processes.
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Affiliation(s)
- Peter J Hunter
- Bioengineering Institute, University of Auckland, New Zealand.
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Littmann L, Monroe MH, Kerns WP, Svenson RH, Gallagher JJ. Brugada syndrome and "Brugada sign": clinical spectrum with a guide for the clinician. Am Heart J 2003; 145:768-78. [PMID: 12766732 DOI: 10.1016/s0002-8703(03)00081-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Patients with the manifest Brugada syndrome have an inordinate risk of sudden death and are candidates for implantation of a defibrillator. The Brugada type electrocardiogram (ECG) abnormality (the "Brugada sign"), however, is known to be associated with a wide range of conditions, many of which may not pose such a threat. Clinicians need guidance in choosing a rational approach for the evaluation and treatment of patients with a finding of the Brugada sign. METHODS A systematic literature search was performed to identify publications on the Brugada syndrome and the Brugada-type ECG abnormality, with special emphasis on analyzing outcomes data. In addition, the ECG database of our institution was reviewed for tracings consistent with the Brugada sign, and, when possible, clinical correlations were made. RESULTS Patients with the Brugada sign and a family history of sudden death or a personal history of syncope are at a high risk of sudden death and therefore should be strongly considered for implantation of a defibrillator. In patients who are hospitalized and critically ill, the Brugada sign is frequently the result of severe hyperkalemia, drug toxicity, or right ventricular injury. In most individuals with no symptoms and without a family history of sudden death, the Brugada sign is likely a normal variant. CONCLUSIONS Most patients with the Brugada sign can be risk-stratified with simple clinical tools. Specific testing for the Brugada syndrome should be reserved for questionable cases and for the research setting. A provisional diagnostic-therapeutic algorithm is offered as a means of assisting the clinician in the evaluation and treatment of patients with the Brugada sign.
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Affiliation(s)
- Laszlo Littmann
- Department of Internal Medicine, Carolinas Medical Center, Charlotte, NC 28232, USA.
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Noda T, Shimizu W, Tanaka K, Chayama K. Prominent J wave and ST segment elevation: serial electrocardiographic changes in accidental hypothermia. J Cardiovasc Electrophysiol 2003; 14:223. [PMID: 12693512 DOI: 10.1046/j.1540-8167.2003.02384.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Takashi Noda
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan
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35
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Nogami A, Nakao M, Kubota S, Sugiyasu A, Doi H, Yokoyama K, Yumoto K, Tamaki T, Kato KI, Hosokawa N, Sagai H, Nakamura H, Nitta JI, Yamauchi Y, Aonuma K. Enhancement of J-ST-segment elevation by the glucose and insulin test in Brugada syndrome. Pacing Clin Electrophysiol 2003; 26:332-7. [PMID: 12687840 DOI: 10.1046/j.1460-9592.2003.00044.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effects of glucose and insulin on J-ST-segment elevation were evaluated in seven men (mean age 45 +/- 10 years) with Brugada syndrome. Six patients had been reanimated from VF and one patient had experienced syncope. The effects of intavenous (1) pilsicainide 50 mg, (2) glucose 50 g, and (3) glucose 50 g plus regular insulin 10 IU on the precordial ECG leads were examined. Pilsicainide significantly enhanced J-ST elevation in all patients and induced VF in 1 patient. A significant accentuation of the abnormal J-ST configuration was observed in all patients at a mean of 51 +/- 40 minutes after glucose and insulin infusion. Changes in blood glucose and serum potassium concentration were 111 +/- 158 mg/dL and -0.30 +/- 0.48 mEq/L, respectively. These changes were not directly related to the ECG changes. Glucose infusion without insulin caused a subtle increase in J-ST elevation. In conclusion, the administration of glucose and insulin safely unmasked or accentuation the J-ST-segment elevation in Brugada syndrome. Blood glucose and insulin concentrations may be factors modulating the circadian or day-to-day ECG variations in this syndrome.
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Affiliation(s)
- Akihiko Nogami
- Div. of Cardiology, Yokohama Rosai Hospital, 3211 Kozukue, Kohoku, Yokohama, Kanagawa 222-0036, Japan.
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Noda T, Shimizu W, Taguchi A, Satomi K, Suyama K, Kurita T, Aihara N, Kamakura S. ST-segment elevation and ventricular fibrillation without coronary spasm by intracoronary injection of acetylcholine and/or ergonovine maleate in patients with Brugada syndrome. J Am Coll Cardiol 2002; 40:1841-7. [PMID: 12446069 DOI: 10.1016/s0735-1097(02)02494-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVES The study examined whether patients with Brugada syndrome are sensitive to vagal stimulation or ischemia. BACKGROUND Experimental studies have suggested that a prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of the action potential dome in the epicardium, but not in the endocardium, give rise to ST-segment elevation and subsequent ventricular fibrillation (VF). METHODS We evaluated the frequency of coronary spasm, augmentation (> or =0.1 mV) of ST-segment elevation in leads V(1) to V(3), and induction of VF by intracoronary injection of acetylcholine (ACh) and/or ergonovine maleate (EM) in 27 symptomatic patients with Brugada syndrome and 30 control subjects. RESULTS The coronary spasm was induced in 3 (11%) of the 27 patients with Brugada syndrome and in 13 (43%) of the 30 control subjects. ST-segment elevation was augmented by 11 (33%) of the 33 right coronary injections (ACh: 6/11 [55%]; EM: 5/22 [23%]), without coronary spasm, but not by any of the left coronary injections in patients with Brugada syndrome. Ventricular fibrillation was induced by 3 (9%) of the 33 right coronary injections (ACh: 2/11 [18%]; EM: 1/22 [5%]), but not by any of the left coronary injections. In contrast, neither ST-segment elevation nor VF was observed in any of the control subjects. CONCLUSIONS Our results support the hypothesis that mild ischemia and vagal influences act additively or synergistically with the substrate responsible for the Brugada syndrome to elevate the ST-segment and precipitate VF. These observations suggest that Brugada patients may be at a higher risk for ischemia-related sudden death.
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Affiliation(s)
- Takashi Noda
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565 Japan
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Di Diego JM, Cordeiro JM, Goodrow RJ, Fish JM, Zygmunt AC, Pérez GJ, Scornik FS, Antzelevitch C. Ionic and cellular basis for the predominance of the Brugada syndrome phenotype in males. Circulation 2002; 106:2004-11. [PMID: 12370227 DOI: 10.1161/01.cir.0000032002.22105.7a] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The Brugada syndrome displays an autosomal dominant mode of transmission with low penetrance. Despite equal genetic transmission of the disease, the clinical phenotype is 8 to 10 times more prevalent in males than in females. The basis for this intriguing sex-related distinction is unknown. The present study tests the hypothesis that the disparity in expression of the Brugada phenotype is a result of a more prominent I(to)-mediated action potential notch in the right ventricular (RV) epicardium of males versus females. METHODS AND RESULTS We studied epicardial tissue slices, arterially perfused wedge preparations, and dissociated epicardial myocytes isolated from male and female canine hearts. RV epicardium action potential phase 1 amplitude was 64.8+/-2.0% of that of phase 2 in males compared with 73.8+/-4.4% in females (P<0.05) at a cycle length of 2000 ms. I(to) density was 26% smaller and time constant for inactivation 17% smaller at +40 mV in female versus male RV epicardial cells (P<0.05). The other functional characteristics of I(to), including the voltage dependence of inactivation and time course of reactivation, were no different between the sexes. Pinacidil caused loss of action potential dome in male, but not female, RV epicardial tissue slices. Terfenadine (5 micromol/L) induced phase 2 reentry in 6 of 7 male but only 2 of 7 female arterially perfused wedge preparations. Two of 6 male and 1 of 2 female preparations developed polymorphic ventricular tachycardia/ventricular fibrillation. CONCLUSIONS Our results suggest that the predominance of the Brugada phenotype in males is a result of the presence of a more prominent I(to) in males versus females.
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Affiliation(s)
- José M Di Diego
- Masonic Medical Research Laboratory, Utica, NY 13501-1787, USA
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Kurita T, Shimizu W, Inagaki M, Suyama K, Taguchi A, Satomi K, Aihara N, Kamakura S, Kobayashi J, Kosakai Y. The electrophysiologic mechanism of ST-segment elevation in Brugada syndrome. J Am Coll Cardiol 2002; 40:330-4. [PMID: 12106940 DOI: 10.1016/s0735-1097(02)01964-2] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES We sought to demonstrate the electrophysiologic (EP) mechanism of the ST-T change in Brugada syndrome. BACKGROUND Brugada syndrome is characterized by various electrocardiographic manifestations (e.g., right bundle branch block, ST-segment elevation, and terminal T-wave inversion in the right precordial leads) and sudden cardiac death caused by ventricular fibrillation. Direct evidence in support of the EP mechanism underlying this intriguing syndrome has been lacking. METHODS Monophasic action potentials (MAPs) were obtained from three patients with the coved-type ST-segment elevation (Brugada patients) and five control patients using the contact electrode method. Epicardial MAPs were recorded during open-chest surgery in all patients. RESULTS A spike-and-dome configuration was documented from epicardial sites of the right ventricular (RV) outflow tract in all Brugada patients but not in control patients. Monophasic action potential recordings from the endocardium with special focus on the RV outflow tract could not demonstrate any morphological abnormalities in three Brugada patients. CONCLUSIONS The presence of a deeply notched action potential in the RV epicardium, but not in endocardium, would be expected to induce a transmural current that would contribute to elevation of the ST-segment in the right precordial leads. The spike-and-dome configuration may also prolong the epicardial action potential, thus contributing to a rapid reversal of the transmural gradients and inscription of an inverted T-wave.
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Affiliation(s)
- Takashi Kurita
- Division of Cardiology, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan.
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Kanda M, Shimizu W, Matsuo K, Nagaya N, Taguchi A, Suyama K, Kurita T, Aihara N, Kamakura S. Electrophysiologic characteristics and implications of induced ventricular fibrillation in symptomatic patients with Brugada syndrome. J Am Coll Cardiol 2002; 39:1799-805. [PMID: 12039494 DOI: 10.1016/s0735-1097(02)01867-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The study examined the electrocardiographic and electrophysiologic characteristics in relation to programmed ventricular stimulation (PVS)-induced ventricular fibrillation (VF), as well as the implications of PVS-induced VF on the recurrence of cardiac events in symptomatic Brugada syndrome. BACKGROUND Brugada syndrome is characterized by ST-segment elevation in the right precordial leads (V(1)-V(3)) and an episode of VF. METHODS Thirty-four symptomatic patients with Brugada syndrome (33 men and 1 woman; 44 +/- 12 years old) were classified into two groups according to the inducibility of VF with PVS: 22 patients with induced VF requiring direct cardioversion for termination (Induced VF group) and 12 patients without induced VF (Noninduced VF group). RESULTS The induced VF group showed a longer QRS duration, a higher incidence of right bundle branch block and late potentials detected on the signal-averaged electrocardiogram, longer His-ventricular intervals and a longer conduction time from the RVOT to the left ventricle at extrastimulation than those in the non-induced VF group. However, there was no significant difference in the recurrence of cardiac events (VF documented by an implantable cardioverter-defibrillator and sudden cardiac death) between the two groups (8 [36%] of 22 patients vs. 7 [58%] of 12 patients) during long-term follow-up (range 1 to 149 months; mean 38). CONCLUSIONS Our data suggest that induction of VF by PVS depends on the severity of depolarization abnormalities but does not predict the recurrence of cardiac events in symptomatic Brugada syndrome, indicating that both depolarization and repolarization abnormalities are important in the development of VF.
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Affiliation(s)
- Munetake Kanda
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
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40
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Cohle SD, Suarez-Mier MP, Aguilera B. Sudden death resulting from lesions of the cardiac conduction system. Am J Forensic Med Pathol 2002; 23:83-9. [PMID: 11953502 DOI: 10.1097/00000433-200203000-00018] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Sudden unexpected deaths in young persons with noncontributory histories, autopsy results, and drug screen results are a common problem in forensic pathology. As part of the evaluation of such cases, the cardiac conduction system (CCS) should be studied. To determine the type and incidence of lethal CCS lesions, the authors reviewed their files of sudden unexpected cardiac deaths with particular attention to cases with causes of death in the conduction system. Cases of sudden cardiac death in patients aged < or=40 years during a 10-year period (Michigan) and a 4 year-period (Spain) were selected from the files. From this group, cases were identified in which the cause of death was a lethal change in the CCS. The portions of the heart containing the CCS were excised, and at least one hematoxylin and eosin slide and at least one trichrome or elastic trichrome slide per block were studied. In the two centers, 381 cases of sudden cardiac death were identified. The most common causes of sudden cardiac death were arteriosclerotic narrowing of the coronary arteries, cardiomyopathy, and myocarditis. In 82 cases, there was no identifiable cause of death even after complete gross and microscopic autopsy was performed, a medical history was obtained, and a drug screen was performed. In 11 cases, the CCS contained lesions that were considered lethal: narrowing of the atrioventricular node artery by fibromuscular hyperplasia (7 cases) and atrioventricular node tumors (4 cases). The 11 cases accounted for 2.9% of the 381 cases of sudden cardiac death and 11.8% of the indeterminable cases. It was concluded that examination of the CCS in deaths in which the gross and microscopic autopsy, history, and drug screen fail to provide a cause of death can yield a cause of death in a significant percentage of cases. If heart block was not documented during life and no explanatory lesions were found during routine cardiac examination, examination of the CCS can yield valuable information.
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Affiliation(s)
- Stephen D Cohle
- Department of Pathology, Spectrum Health East, Grand Rapids, Michigan 49506, USA
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41
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Abstract
The Brugada syndrome describes a subgroup of patients at risk for the occurrence of ventricular fibrillation who have no definable structural heart disease associated with a right bundle branch block conduction pattern and ST-segment elevation in the right precordial leads. This syndrome is caused by genetic defects in the alpha subunit of the sodium channel. This defect causes a reduction in the sodium channel current, which accentuates the epicardial action potential notch leading to ST-segment elevation. Sodium channel blockers can potentiate these findings and screen for patients with intermittent baseline electrocardiographic findings. Because of the poor prognosis of such patients, symptomatic patients should be treated with an implantable cardioverter-defibrillator.
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Affiliation(s)
- Gerald V Naccarelli
- Division of Cardiology, Cardiovascular Center, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA
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42
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Kyndt F, Probst V, Potet F, Demolombe S, Chevallier JC, Baro I, Moisan JP, Boisseau P, Schott JJ, Escande D, Le Marec H. Novel SCN5A mutation leading either to isolated cardiac conduction defect or Brugada syndrome in a large French family. Circulation 2001; 104:3081-6. [PMID: 11748104 DOI: 10.1161/hc5001.100834] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The SCN5A gene encoding the human cardiac sodium channel alpha subunit plays a key role in cardiac electrophysiology. Mutations in SCN5A lead to a large spectrum of phenotypes, including long-QT syndrome, Brugada syndrome, and isolated progressive cardiac conduction defect (Lenègre disease). METHODS AND RESULTS In the present study, we report the identification of a novel single SCN5A missense mutation causing either Brugada syndrome or an isolated cardiac conduction defect in the same family. A G-to-T mutation at position 4372 was identified by direct sequencing and was predicted to change a glycine for an arginine (G1406R) between the DIII-S5 and DIII-S6 domain of the sodium channel protein. Among 45 family members, 13 were carrying the G1406R SCN5A mutation. Four individuals from 2 family collateral branches showed typical Brugada phenotypes, including ST-segment elevation in the right precordial leads and right bundle branch block. One symptomatic patient with the Brugada phenotype required implantation of a cardioverter-defibrillator. Seven individuals from 3 other family collateral branches had isolated cardiac conduction defects but no Brugada phenotype. Three flecainide test were negative. One patient with an isolated cardiac conduction defect had an episode of syncope and required pacemaker implantation. An expression study of the G1406R-mutated SCN5A showed no detectable Na(+) current but normal protein trafficking. CONCLUSIONS We conclude that the same mutation in the SCN5A gene can lead either to Brugada syndrome or to an isolated cardiac conduction defect. Our findings suggest that modifier gene(s) may influence the phenotypic consequences of a SCN5A mutation.
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Affiliation(s)
- F Kyndt
- Laboratoire de Physiopathologie et de Pharmacologie Cellulaires et Moléculaires, INSERM U533, Paris, France
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Abstract
In this review, the up-to-date understanding of the molecular basis of disorders causing sudden death will be described. Two arrhythmic disorders causing sudden death have recently been well described at the molecular level, the long QT syndromes (LQTS) and Brugada syndrome, and in this article we will review the current scientific knowledge of each disease. A third disorder, hypertrophic cardiomyopathy (HCM), a myocardial disorder causing sudden death, has also been well studied. Finally, a disorder in which both myocardial abnormalities and rhythm abnormalities coexist, arrhythmogenic right ventricular dysplasia (ARVD) will also be described. The role of the pathologist in these studies will be highlighted.
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MESH Headings
- Animals
- Arrhythmogenic Right Ventricular Dysplasia/genetics
- Arrhythmogenic Right Ventricular Dysplasia/pathology
- Arrhythmogenic Right Ventricular Dysplasia/physiopathology
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/pathology
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Death, Sudden, Cardiac/etiology
- Death, Sudden, Cardiac/pathology
- Dogs
- Genetic Predisposition to Disease
- Humans
- Ion Channels
- Long QT Syndrome/genetics
- Long QT Syndrome/pathology
- Long QT Syndrome/physiopathology
- Molecular Biology
- Ventricular Fibrillation/genetics
- Ventricular Fibrillation/pathology
- Ventricular Fibrillation/physiopathology
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Affiliation(s)
- J A Towbin
- Department of Pediatrics (Cardiology), Texas Children's Hospital and Baylor College of Medicine, One Baylor Plaza, Room 333E, Houston, TX 77030, USA.
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Matsuo K, Akahoshi M, Nakashima E, Suyama A, Seto S, Hayano M, Yano K. The prevalence, incidence and prognostic value of the Brugada-type electrocardiogram: a population-based study of four decades. J Am Coll Cardiol 2001; 38:765-70. [PMID: 11527630 DOI: 10.1016/s0735-1097(01)01421-8] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES We sought to demonstrate the prevalence, incidence and prognostic value of the Brugada-type electrocardiogram (ECG) in a general population. BACKGROUND The Brugada syndrome is characterized by evidence of right bundle branch block and ST segment elevation in the right precordial leads, as well as sudden death caused by ventricular fibrillation. However, the natural history of the Brugada-type ECG remains unclear. METHODS We investigated 4,788 subjects (1,956 men and 2,832 women) who were <50 years old in 1958 and had undergone biennial health examinations, including electrocardiography, through 1999. The Brugada-type ECG was defined as a terminal r' wave in lead V(1) and ST segment elevation > or =0.1 mV in leads V(1) and V(2). Unexpected death was defined as sudden death or unexplained accidental death. RESULTS There were a total of 32 Brugada-type ECG cases; the prevalence and incidence were 146.2 in 100,000 persons and 14.2 persons per 100,000 person-years, respectively. The incidence was nine times higher among men than women, and the average age at presentation was 45 +/- 10.5 years. The Brugada-type ECG appeared intermittently in most cases and was found in 26% of subjects who died unexpectedly. Cox survival analysis revealed that mortality from unexpected death was significantly higher in subjects with a Brugada-type ECG than in control subjects (p < 0.01). Unexpected deaths were more frequent among subjects with the Brugada-type ECG who had a history of syncope (p < 0.05). CONCLUSIONS The Brugada-type ECG is not a very rare condition in the adult Japanese population. Subjects with a Brugada-type ECG have an increased risk of unexpected death.
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Affiliation(s)
- K Matsuo
- Third Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan.
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Furuhashi M, Uno K, Tsuchihashi K, Nagahara D, Hyakukoku M, Ohtomo T, Satoh S, Nishimiya T, Shimamoto K. Prevalence of asymptomatic ST segment elevation in right precordial leads with right bundle branch block (Brugada-type ST shift) among the general Japanese population. Heart 2001; 86:161-6. [PMID: 11454832 PMCID: PMC1729874 DOI: 10.1136/heart.86.2.161] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE To examine the modality and morbidity of asymptomatic ST segment elevation in leads V1 to V3 with right bundle branch block (Brugada-type ST shift). METHODS 8612 Japanese subjects (5987 men and 2625 women, mean age 49.2 years) who underwent a health check up in 1997 were investigated. Those with Brugada-type ST shift underwent the following further examinations over a two year period after the initial check up: ECG, echocardiogram, 24 hour Holter monitoring, treadmill exercise testing, signal averaged ECG, and slow kinetic sodium channel blocker loading test (cibenzoline, 1.4 mg/kg). RESULTS Asymptomatic Brugada-type ST shift was found in 12 of 8612 (0.14%) subjects. Eleven of these 12 subjects were followed up. Follow up ECG exhibited persistent Brugada-type ST shift in seven of 11 (63.6%) subjects. ST shift was transformed from a saddle back to a coved type in three subjects. None of the subjects had morphological abnormalities or abnormal tachyarrhythmias. Positive late potentials were found in seven of 11 (63.6%) subjects. Augmentation of ST shift was shown by both submaximal exercise and drug administration in one of the 11 subjects (9.1%). CONCLUSIONS Asymptomatic subjects with Brugada-type ST shift were not unusual, at a rate of 0.14% in the general Japanese population. Almost all of the subjects had some abnormalities in non-invasive secondary examinations. Additional and prospective studies are needed to confirm the clinical significance and the prognosis of asymptomatic Brugada-type ST shift.
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Affiliation(s)
- M Furuhashi
- Second Department of Internal Medicine, Sapporo Medical University School of Medicine, S-1, W-16, Chuo-ku, Sapporo 060-0061, Japan.
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46
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Furuhashi M, Uno K, Tsuchihashi K, Nagahara D, Hyakukoku M, Ohtomo T, Satoh S, Nishimiya T, Shimamoto K. Prevalence of asymptomatic ST segment elevation in right precordial leads with right bundle branch block (Brugada-type ST shift) among the general Japanese population. BRITISH HEART JOURNAL 2001. [DOI: 10.1136/hrt.86.2.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVETo examine the modality and morbidity of asymptomatic ST segment elevation in leads V1 to V3 with right bundle branch block (Brugada-type ST shift).METHODS8612 Japanese subjects (5987 men and 2625 women, mean age 49.2 years) who underwent a health check up in 1997 were investigated. Those with Brugada-type ST shift underwent the following further examinations over a two year period after the initial check up: ECG, echocardiogram, 24 hour Holter monitoring, treadmill exercise testing, signal averaged ECG, and slow kinetic sodium channel blocker loading test (cibenzoline, 1.4 mg/kg).RESULTSAsymptomatic Brugada-type ST shift was found in 12 of 8612 (0.14%) subjects. Eleven of these 12 subjects were followed up. Follow up ECG exhibited persistent Brugada-type ST shift in seven of 11 (63.6%) subjects. ST shift was transformed from a saddle back to a coved type in three subjects. None of the subjects had morphological abnormalities or abnormal tachyarrhythmias. Positive late potentials were found in seven of 11 (63.6%) subjects. Augmentation of ST shift was shown by both submaximal exercise and drug administration in one of the 11 subjects (9.1%).CONCLUSIONSAsymptomatic subjects with Brugada-type ST shift were not unusual, at a rate of 0.14% in the general Japanese population. Almost all of the subjects had some abnormalities in non-invasive secondary examinations. Additional and prospective studies are needed to confirm the clinical significance and the prognosis of asymptomatic Brugada-type ST shift.
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Brugada J, Brugada R, Brugada P. Pharmacological and device approach to therapy of inherited cardiac diseases associated with cardiac arrhythmias and sudden death. J Electrocardiol 2001; 33 Suppl:41-7. [PMID: 11265735 DOI: 10.1054/jelc.2000.20322] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A genetic origin in diseases like the long QT syndrome, the Brugada syndrome, or hypertrophic cardiomyopathy have been identified over the past years. These diseases have in common that they may result in sudden cardiac death of the patient. Recognition of patients based on their phenotype and application in clinical practice of the knowledge acquired on the genetic basis may have a major impact on how we approach them. In the long QT syndrome several mutations have been identified both in the sodium and in the potassium channels. The different electrophysiological effects of the mutations lead to a common phenotype: prolongation of the QT interval; but also to a common clinical impact: occurrence of malignant ventricular arrhythmias. Genetics should help us in treating in a more rational way our patients depending on the type of mutation. In the Brugada syndrome, mutations affecting the sodium channel have been so far identified. The results are electrophysiologically opposite to the ones observed in the long QT syndrome. Thus different mutations in the same gene lead to different functional consequences. Again, identification and study of the right mutation may lead to a more rational treatment directed to correct the malfunction of the channel.
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Affiliation(s)
- J Brugada
- Arrhythmia Section, Cardiovascular Institute, Hospital Clínic,University of Barcelona, Spain.
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48
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Ikeda T, Sakurada H, Sakabe K, Sakata T, Takami M, Tezuka N, Nakae T, Noro M, Enjoji Y, Tejima T, Sugi K, Yamaguchi T. Assessment of noninvasive markers in identifying patients at risk in the Brugada syndrome: insight into risk stratification. J Am Coll Cardiol 2001; 37:1628-34. [PMID: 11345376 DOI: 10.1016/s0735-1097(01)01197-4] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES The aim of this study was to compare the use of various noninvasive markers for detecting risk of life-threatening arrhythmic events in patients with Brugada syndrome. BACKGROUND The role of conduction disturbance in arrhythmogenesis of the syndrome is controversial, whereas it is well established that repolarization abnormalities are responsible for arrhythmias. The value of noninvasive markers reflecting conduction or repolarization abnormalities in identifying patients at risk for significant arrhythmias has not been shown. METHODS We assessed late potentials (LP) using signal-averaged electrocardiography (ECG), microvolt T-wave alternans (TWA), and corrected QT-interval dispersion (QTD) in 44 consecutive patients who had ECGs showing a pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 but structurally normal hearts. The patients were compared with 30 normal individuals. RESULTS Eleven patients were excluded from data analysis because of an absence of ECG manifestations of Brugada syndrome at the time of the tests. A history of life-threatening events defined as syncope and aborted sudden death was present in 19 of 33 patients (58%); in 15 of the 19 patients, stimulation induced ventricular fibrillation or polymorphic ventricular tachycardia. The LP were present in 24 of 33 patients (73%); TWA were present in 5 of 31 patients (16%); and a QTD >50 ms was present in 9 of 33 patients (27%). The incidence of LP in Brugada patients was significantly (p < 0.0001) higher than in the controls, whereas incidences of TWA and QTD were not significantly different. Multivariate logistic regression analysis revealed that the presence of LP had the most significant correlation to the occurrence of life-threatening events (p = 0.006). CONCLUSIONS Late potentials are a noninvasive risk stratifier in patients with Brugada syndrome. These results may support the idea that conduction disturbance per se is arrhythmogenic.
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Affiliation(s)
- T Ikeda
- Third Department of Internal Medicine, Ohashi Hospital, Toho University School of Medicine, Japan.
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49
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Marcus FI. Electrocardiographic features of inherited diseases that predispose to the development of cardiac arrhythmias, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy/dysplasia, and Brugada syndrome. J Electrocardiol 2001; 33 Suppl:1-10. [PMID: 11265707 DOI: 10.1054/jelc.2000.20360] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Analysis of the 12-lead electrocardiogram (ECG) provides important diagnostic and prognostic information in the long QT syndrome. The clinical diagnosis of long QT syndrome is determined by the presence of a QTc > or = 0.44 sec. A normal QTc does not exclude a family member from being a genetic carrier. The ECG patterns of depolarization, the ST segment and shape of the T-wave can provide important clues as to the affected gene, particularly in conjunction with clinical information as to the precipitating causes of syncope or cardiac events. In arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), the typical ECG pattern consists of T-wave inversion beyond lead V1. Evidence of right ventricular parietal block is manifest by a QRS duration in V1 > or = 110 msec and a longer QRS duration in the right then left precordial leads. Evidence of slow fractionated conduction is present as epsilon waves. The signal averaged ECG may show exceedingly long and low late potentials. Information regarding the risk of sudden death may also be obtained from the ECG. The ECG changes alone or in combination can provide strong evidence for the diagnosis of ARVC/D and helps to differentiate ARVC/D from right ventricular outflow tract (RVOT) tachycardia. The typical pattern of the ECG in the Brugada syndrome is ST segment elevation in the right precordial leads. This abnormality can be dormant and elicited by administration of drugs that cause Na channel blockade, such as ajmaline or type 1a or 1C antiarrhythmic drugs. Individuals who do not have the Brugada ECG findings at baseline but have this pattern induced by antiarrhythmic drugs are also at risk for sudden death. Further risk stratification may be obtained in the asymptomatic patients if ventricular fibrillation is induced at electrophysiological study.
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Affiliation(s)
- F I Marcus
- Sarver Heart Center, University of Arizona College of Medicine, Tucson 85724-5037, USA.
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50
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Abstract
The Brugada syndrome is an arrhythmic syndrome characterized by a right bundle branch block pattern and ST segment elevation in the right precordial leads of the electrocardiogram in conjunction with a high incidence of sudden death secondary to ventricular tachyarrhythmias. No evidence of structural heart disease is noted during diagnostic evaluation of these patients. In 25% of families, there appears to be an autosomal dominant mode of transmission with variable expression of the abnormal gene. Mutations have been identified in the gene that encodes the alpha subunit of the sodium channel (SCN5A) on chromosome 3. This genetic defect causes a reduction in the density of the sodium current and explains the worsening of the above electrocardiographic abnormalities when patients are treated with sodium channel blocking antiarrhythmic agents, which further diminish the already reduced sodium current. The prognosis is poor with up to a 10% per year mortality. Antiarrhythmic drugs including beta-blockers and amiodarone have no benefit in prolonging survival. The treatment of choice is the insertion of an implantable cardioverter-defibrillator.
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Affiliation(s)
- G V Naccarelli
- Division of Cardiology, Cardiovascular Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
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