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Takahashi K, Morioka H, Uemura S, Okura T, Inoue K. Accidental Hypothermia-Induced J Wave Coupled With Giant R Wave Augmented by Premature Atrial Contraction: A Case Report. Cureus 2024; 16:e60644. [PMID: 38903283 PMCID: PMC11187455 DOI: 10.7759/cureus.60644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2024] [Indexed: 06/22/2024] Open
Abstract
The 12-lead electrocardiographic findings in hypothermia include the presence of J waves; prolongation of the PR, QRS, and QT intervals; and atrial and ventricular dysrhythmias. Among these findings, the J wave, known as the Osborn wave, is considered pathognomonic. In 1953, the J wave was reported as a specific response to hypothermia in dogs, representing the current at the site of injury instead of a widening of the QRS complex that occurs caused by a conduction delay. The J wave is often accompanied by ventricular fibrillation. For the past 28 years, it was assumed that the hypothermia-induced J wave was mediated by the transient outward current. However, it was recently been reported that the J waves in some patients with hypothermia can be considered delayed conduction-related waveforms. Here, we present a case of hypothermia-induced J waves together with giant R waves, which have not been previously reported during hypothermia, augmented by short RR intervals arising from premature atrial contractions. Our observations indicate that the underlying mechanism for the genesis of J waves is indeed conduction delay and not transient outward currents.
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Affiliation(s)
- Koji Takahashi
- Department of Cardiology, Yawatahama City General Hospital, Ehime, JPN
| | - Hiroe Morioka
- Department of Cardiology, Yawatahama City General Hospital, Ehime, JPN
| | - Shigeki Uemura
- Department of Cardiology, Yawatahama City General Hospital, Ehime, JPN
| | - Takafumi Okura
- Department of Cardiology, Yawatahama City General Hospital, Ehime, JPN
| | - Katsuji Inoue
- Department of Community Emergency Medicine, Ehime University Graduate School of Medicine, Ehime, JPN
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Ly NB, Kim YR, Lee KH, Yoon N, Park HW. Case Report: Comprehensive evaluation of ECG phenotypes and genotypes in a family with Brugada syndrome carrying SCN5A-R376H. Front Cardiovasc Med 2024; 11:1334096. [PMID: 38559671 PMCID: PMC10978698 DOI: 10.3389/fcvm.2024.1334096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 03/04/2024] [Indexed: 04/04/2024] Open
Abstract
Background Brugada syndrome (BrS) is a channelopathy that can lead to sudden cardiac death in the absence of structural heart disease. Patients with BrS can be asymptomatic or present with symptoms secondary to polymorphic ventricular tachycardia or ventricular fibrillation. Even though BrS can exhibit autosomal dominant inheritance, it is not easy to identify the phenotype and genotype in a family thoroughly. Case We report the case of a 20-year-old man with variants in SCN5A and RyR2 genes who was resuscitated from sudden cardiac death during sleep due to a ventricular fibrillation. The patient did not have underlying diseases. The routine laboratory results, imaging study, coronary angiogram, and echocardiogram (ECG) were normal. A type 1 BrS pattern was identified in one resting ECG. Furthermore, prominent J wave accentuation with PR interval prolongation was identified during therapeutic hypothermia. Therefore, we were easily able to diagnose BrS. For secondary prevention, the patient underwent implantable cardioverter defibrillator implantation. Before discharge, a genetic study was performed using next-generation sequencing. Genotyping was performed in the first-degree relatives, and ECG evaluations of almost all maternal and paternal family members were conducted. The proband and his mother showed SCN5A-R376H and RyR2-D4038Y variants. However, his mother did not show the BrS phenotype on an ECG. One maternal aunt and uncle showed BrS phenotypes. Conclusion Genetics alone cannotdiagnose BrS. However, genetics could supply evidence or direction for evaluating ECG phenotypes in family groups. This case report shows how family evaluation using ECGs along with a genetic study can be used in BrS diagnosis.
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Affiliation(s)
- Ngoc Bao Ly
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Yoo Ri Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
- Department of Cardiovascular Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Ki Hong Lee
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
- Department of Cardiovascular Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Namsik Yoon
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
- Department of Cardiovascular Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Hyung Wook Park
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
- Department of Cardiovascular Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea
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Christie S, Idris S, Bennett RG, Deyell MW, Roston T, Laksman Z. Trigger and Substrate Mapping and Ablation for Ventricular Fibrillation in the Structurally Normal Heart. J Cardiovasc Dev Dis 2023; 10:jcdd10050200. [PMID: 37233167 DOI: 10.3390/jcdd10050200] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 04/28/2023] [Accepted: 04/29/2023] [Indexed: 05/27/2023] Open
Abstract
Sudden cardiac death (SCD) represents approximately 50% of all cardiovascular mortality in the United States. The majority of SCD occurs in individuals with structural heart disease; however, around 5% of individuals have no identifiable cause on autopsy. This proportion is even higher in those <40 years old, where SCD is particularly devastating. Ventricular fibrillation (VF) is often the terminal rhythm leading to SCD. Catheter ablation for VF has emerged as an effective tool to alter the natural history of this disease among high-risk individuals. Important advances have been made in the identification of several mechanisms involved in the initiation and maintenance of VF. Targeting the triggers of VF as well as the underlying substrate that perpetuates these lethal arrhythmias has the potential to eliminate further episodes. Although important gaps remain in our understanding of VF, catheter ablation has become an important option for individuals with refractory arrhythmias. This review outlines a contemporary approach to the mapping and ablation of VF in the structurally normal heart, specifically focusing on the following major conditions: idiopathic ventricular fibrillation, short-coupled ventricular fibrillation, and the J-wave syndromes-Brugada syndrome and early-repolarization syndrome.
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Affiliation(s)
- Simon Christie
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
| | - Sami Idris
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
| | - Richard G Bennett
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
| | - Marc W Deyell
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
| | - Thomas Roston
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
| | - Zachary Laksman
- Faculty of Medicine, Division of Cardiology, University of British Columbia, Gordon & Leslie Diamond Health Care Centre, 2775 Laurel St., 9th Floor, Vancouver, BC V5Z 1M9, Canada
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Electrocardiographic Changes Associated with Early Repolarization Pattern in Healthy Young Males. MEDICINA (KAUNAS, LITHUANIA) 2022; 58:medicina58081048. [PMID: 36013515 PMCID: PMC9415057 DOI: 10.3390/medicina58081048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/25/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022]
Abstract
Background and Objectives: Early repolarization pattern (ERP) has recently been shown to be related with an increased risk of ventricular arrhythmias in susceptible individuals. Materials and Methods: We studied the ERP-associated ECG changes, with potential clinical relevance, in 220 young (age 22.1 ± 1.6 years), healthy, male subjects using 12-lead ECG recordings. A total of 38 subjects (17.3%) fulfilled the diagnostic criteria for ERP, and a total of 90 ECG characteristics were compared between the groups of subjects with and without ERP. Results: None of the ECGs were pathological, and 22 ECG parameters differed significantly (p < 0.05) between the subjects with and without ERP. Among them, the P wave-related parameters (e.g., average P wave duration: 101.5 ± 9.2 ms vs. 106.8 ± 9.9 ms, p = 0.004) and the presence of fragmented QRS complexes (67.6% vs. 92.1%, p = 0.002) revealed a potential propensity for atrial and ventricular arrhythmogenesis. The time-domain parameters of repolarization, those not corrected for QRS duration, showed shorter values (e.g., Tpeak-Tend interval: 70.9 ± 8.1 ms vs. 67.8 ± 8.0 ms, p = 0.036), reflecting the accelerated repolarization. Conclusions: Certain ECG characteristics seem to be more associated with ERP. The clinical significance of this finding at the individual level needs further prospective investigations.
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Zhang Z, Chen PS, Weiss JN, Qu Z. Why Is Only Type 1 Electrocardiogram Diagnostic of Brugada Syndrome? Mechanistic Insights From Computer Modeling. Circ Arrhythm Electrophysiol 2022; 15:e010365. [PMID: 34963310 PMCID: PMC8766947 DOI: 10.1161/circep.121.010365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Three types of characteristic ST-segment elevation are associated with Brugada syndrome but only type 1 is diagnostic. Why only type 1 ECG is diagnostic remains unanswered. METHODS Computer simulations were performed in single cells, 1-dimensional cables, and 2-dimensional tissues to investigate the effects of the peak and late components of the transient outward potassium current (Ito), sodium current, and L-type calcium current (ICa,L) as well as other potassium currents on the genesis of ECG morphologies and phase 2 reentry (P2R). RESULTS Although a sufficiently large peak Ito was required to result in the type 1 ECG pattern and P2R, increasing the late component of Ito converted type 1 ECG to type 2 ECG and suppressed P2R. Increasing the peak Ito promoted spiral wave breakup, potentiating the transition from tachycardia to fibrillation, but increasing the late Ito prevented spiral wave breakup by flattening the action potential duration restitution and preventing P2R. A sufficiently large ICa,L conductance was needed for P2R to occur, but once above the critical conductance, blocking ICa,L promoted P2R. However, selectively blocking the window and late components of ICa,L suppressed P2R, countering the effect of the late Ito. Blocking either the peak or late components of sodium current promoted P2R, with the late sodium current blockade having the larger effect. As expected, increasing other potassium currents potentiated P2R, with ATP-sensitive potassium current exhibiting a larger effect than rapid and slow component of the delayed rectifier potassium current. CONCLUSIONS The peak Ito promotes type 1 ECG and P2R, whereas the late Ito converts type 1 ECG to type 2 ECG and suppresses P2R. Blocking the peak ICa,L and either the peak or the late sodium current promotes P2R, whereas blocking the window and late ICa,L suppresses P2R. These results provide important insights into the mechanisms of arrhythmogenesis and potential therapeutic targets for treatment of Brugada syndrome. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Zhaoyang Zhang
- Department of physics, School of Physical Science and Technology, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Peng-Sheng Chen
- Department of Cardiology, Cedars Sinai Medical Center, Los Aneles, CA 90048, USA
| | - James N. Weiss
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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