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1.
Int Heart J ; 61(5): 927-935, 2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-32879263

RESUMO

We prospectively collected device and heart rate data through remote monitoring (RM) of patients with an implantable cardioverter defibrillator (ICD). The objective was to identify the predictors of lethal arrhythmic events (VT/VF).Thirty-three patients (mean age: 50 years) with ICDs [with functionality of heart rate variability (HRV) analysis] were divided into two groups [VT/VF (+), VT/VF (-) ]. Clinical, device (ventricular lead impedance; amplitude of ventricular electrogram), and HRV data were compared between the two groups. The NN interval-index (SDNNi) was calculated for every 5 minutes, and the mean, maximum, minimum, and standard deviation of SDNNi during the 24-hour period were used.During the observation period of 13 ± 10 months, 10 patients experienced VT/VF events. Total mean, max, and min SDNNi were higher in the VT/VF (+) than the VT/VF (-) group (132.9 ± 9.3 versus 93.5 ± 6.1, P = 0.0013; 214.6 ± 10.6 versus 167.0 ± 7.0, P = 0.0007; 71.2 ± 7.5 versus 43.9 ± 4.9, P = 0.0047). On logistic regression analysis, a total mean SDNNi of 100.1, max SDNNi of 185.0 and min SDNNi of 52.0 as cut-off values for prediction of a VT/VF event demonstrated significant receiver operating characteristic (ROC) curves (AUC = 0.86, P = 0.0007; AUC = 0.84, P = 0.0005; AUC = 0.78, P = 0.0030). The max ΔSDNNi, i.e., difference from baseline SDNNi, and min ΔSDNNi in 7 and 28 days preceding VT/VF events were significant predictors of VT/VF events.Time-domain HRV analysis through a RM system may help identify patients at high risk of lethal arrhythmic events; in addition, it may help predict the occurrence of lethal arrhythmic events in specific cases.


Assuntos
Morte Súbita Cardíaca/prevenção & controle , Desfibriladores Implantáveis , Frequência Cardíaca , Taquicardia Ventricular/epidemiologia , Fibrilação Ventricular/epidemiologia , Adulto , Idoso , Síndrome de Brugada/fisiopatologia , Cardiomiopatias/fisiopatologia , Feminino , Humanos , Síndrome do QT Longo/fisiopatologia , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/fisiopatologia , Tecnologia de Sensoriamento Remoto , Taquicardia Ventricular/fisiopatologia , Fibrilação Ventricular/fisiopatologia
2.
Am J Cardiol ; 131: 125-126, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32718558

RESUMO

A 64-year-old man with known coronary disease presented to the hospital with sinus bradycardia, chest pain, and normal cardiac enzymes. During an exercise stress test he developed ventricular fibrillation that spontaneously resolved.


Assuntos
Stents , Fibrilação Ventricular/fisiopatologia , Fibrilação Ventricular/terapia , Eletrocardiografia , Teste de Esforço , Massagem Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Remissão Espontânea
3.
PLoS One ; 15(7): e0235315, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32634172

RESUMO

BACKGROUND: The effect of paramedic crew size in the resuscitation of patients with out-of-hospital cardiac arrest (OHCA) remains inconclusive. We hypothesised that teams with a larger crew size have better resuscitation performance including chest compression fraction (CCF), advanced life support (ALS), and teamwork performance than those with a smaller crew size. METHODS: We conducted a randomized controlled study in a simulation setting. A total of 140 paramedics from New Taipei City were obtained by stratified sampling and were randomly allocated to 35 teams with crew sizes of 2, 3, 4, 5, and 6 (i.e. 7 teams in every paramedic crew size). A scenario involving an OHCA patient who experienced ventricular fibrillation and was attached to a cardiopulmonary resuscitation (CPR) machine was simulated. The primary outcome was the overall CCF; the secondary outcomes were the CCF in manual CPR periods, time from the first dose of epinephrine until the accomplishment of intubation, and teamwork performance. Tasks affecting the hands-off time during CPR were also analysed. RESULTS: In all 35 teams with crew sizes of 2, 3, 4, 5, and 6, the overall CCFs were 65.1%, 64.4%, 70.7%, 72.8%, and 71.5%, respectively (P = 0.148). Teams with a crew size of 5 (58.4%, 61.8%, 68.9%, 72.4%, and 68.7%, P<0.05) had higher CCF in manual CPR periods and better team dynamics. Time to the first dose of epinephrine was significantly shorter in teams with 4 paramedics, while time to completion of intubation was shortest in teams with 6 paramedics. Troubleshooting of M-CPR machine decreased the hands-off time during resuscitation (39 s), with teams comprising 2 paramedics having the longest hands-off time (63s). CONCLUSION: Larger paramedic crew size (≧4 paramedics) did not significantly increase the overall CCF in OHCA resuscitation but showed higher CCF in manual CPR period before the setup of the CPR machine. A crew size of ≧4 paramedics can also shorten the time of ALS interventions, while teams with 5 paramedics will have the best teamwork performance. Paramedic teams with a smaller crew size should focus more on the quality of manual CPR, teamwork, and training how to troubleshoot a M-CPR machine.


Assuntos
Pessoal Técnico de Saúde/estatística & dados numéricos , Reanimação Cardiopulmonar/métodos , Serviços Médicos de Emergência/métodos , Parada Cardíaca Extra-Hospitalar/prevenção & controle , Adulto , Cuidados Críticos/métodos , Auxiliares de Emergência , Medicina de Emergência/métodos , Epinefrina/administração & dosagem , Feminino , Humanos , Intubação/métodos , Masculino , Parada Cardíaca Extra-Hospitalar/epidemiologia , Parada Cardíaca Extra-Hospitalar/patologia , Fibrilação Ventricular/fisiopatologia , Fibrilação Ventricular/prevenção & controle
4.
Circ Arrhythm Electrophysiol ; 13(8): e006875, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32628505

RESUMO

BACKGROUND: Long QT syndrome has been associated with sudden cardiac death likely caused by early afterdepolarizations (EADs) and polymorphic ventricular tachycardias (PVTs). Suppressing the late sodium current (INaL) may counterbalance the reduced repolarization reserve in long QT syndrome and prevent EADs and PVTs. METHODS: We tested the effects of the selective INaL blocker GS967 on PVT induction in a transgenic rabbit model of long QT syndrome type 2 using intact heart optical mapping, cellular electrophysiology and confocal Ca2+ imaging, and computer modeling. RESULTS: GS967 reduced ventricular fibrillation induction under a rapid pacing protocol (n=7/14 hearts in control versus 1/14 hearts at 100 nmol/L) without altering action potential duration or restitution and dispersion. GS967 suppressed PVT incidences by reducing Ca2+-mediated EADs and focal activity during isoproterenol perfusion (at 30 nmol/L, n=7/12 and 100 nmol/L n=8/12 hearts without EADs and PVTs). Confocal Ca2+ imaging of long QT syndrome type 2 myocytes revealed that GS967 shortened Ca2+ transient duration via accelerating Na+/Ca2+ exchanger (INCX)-mediated Ca2+ efflux from cytosol, thereby reducing EADs. Computer modeling revealed that INaL potentiates EADs in the long QT syndrome type 2 setting through (1) providing additional depolarizing currents during action potential plateau phase, (2) increasing intracellular Na+ (Nai) that decreases the depolarizing INCX thereby suppressing the action potential plateau and delaying the activation of slowly activating delayed rectifier K+ channels (IKs), suggesting important roles of INaL in regulating Nai. CONCLUSIONS: Selective INaL blockade by GS967 prevents EADs and abolishes PVT in long QT syndrome type 2 rabbits by counterbalancing the reduced repolarization reserve and normalizing Nai. Graphic Abstract: A graphic abstract is available for this article.


Assuntos
Antiarrítmicos/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Síndrome do QT Longo/tratamento farmacológico , Miócitos Cardíacos/efeitos dos fármacos , Piridinas/farmacologia , Bloqueadores dos Canais de Sódio/farmacologia , Canais de Sódio/efeitos dos fármacos , Taquicardia Ventricular/prevenção & controle , Triazóis/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Animais Geneticamente Modificados , Sinalização do Cálcio/efeitos dos fármacos , Simulação por Computador , Canais de Potássio de Retificação Tardia/metabolismo , Modelos Animais de Doenças , Feminino , Síndrome do QT Longo/genética , Síndrome do QT Longo/metabolismo , Síndrome do QT Longo/fisiopatologia , Masculino , Modelos Cardiovasculares , Miócitos Cardíacos/metabolismo , Coelhos , Canais de Sódio/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Taquicardia Ventricular/genética , Taquicardia Ventricular/metabolismo , Taquicardia Ventricular/fisiopatologia , Fatores de Tempo , Fibrilação Ventricular/genética , Fibrilação Ventricular/metabolismo , Fibrilação Ventricular/fisiopatologia , Fibrilação Ventricular/prevenção & controle
5.
Cardiovasc Drugs Ther ; 34(5): 619-628, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32562104

RESUMO

PURPOSE: Pralidoxime potentiated the pressor effect of adrenaline and facilitated restoration of spontaneous circulation (ROSC) after prolonged cardiac arrest. In this study, we hypothesised that pralidoxime would hasten ROSC in a model with a short duration of untreated ventricular fibrillation (VF). We also hypothesised that potentiation of the pressor effect of adrenaline by pralidoxime would not be accompanied by worsening of the adverse effects of adrenaline. METHODS: After 5 min of VF, 20 pigs randomly received either pralidoxime (40 mg/kg) or saline, in combination with adrenaline, during cardiopulmonary resuscitation (CPR). Coronary perfusion pressure (CPP) during CPR, and ease of resuscitation were compared between the groups. Additionally, haemodynamic data, severity of ventricular arrhythmias, and cerebral microcirculation were measured during the 1-h post-resuscitation period. Cerebral microcirculatory blood flow and brain tissue oxygen tension (PbtO2) were measured on parietal cortices exposed through burr holes. RESULTS: All animals achieved ROSC. The pralidoxime group had higher CPP during CPR (P = 0.014) and required a shorter duration of CPR (P = 0.024) and smaller number of adrenaline doses (P = 0.024). During the post-resuscitation period, heart rate increased over time in the control group, and decreased steadily in the pralidoxime group. No inter-group differences were observed in the incidences of ventricular arrhythmias, cerebral microcirculatory blood flow, and PbtO2. CONCLUSION: Pralidoxime improved CPP and hastened ROSC in a model with a short duration of untreated VF. The potentiation of the pressor effect of adrenaline was not accompanied by the worsening of the adverse effects of adrenaline.


Assuntos
Agonistas Adrenérgicos/farmacologia , Reanimação Cardiopulmonar , Epinefrina/farmacologia , Parada Cardíaca/terapia , Hemodinâmica/efeitos dos fármacos , Compostos de Pralidoxima/farmacologia , Fibrilação Ventricular/terapia , Animais , Modelos Animais de Doenças , Parada Cardíaca/diagnóstico , Parada Cardíaca/fisiopatologia , Recuperação de Função Fisiológica , Sus scrofa , Fatores de Tempo , Fibrilação Ventricular/diagnóstico , Fibrilação Ventricular/fisiopatologia
6.
Anaesth Crit Care Pain Med ; 39(3): 393-394, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32562808
7.
PLoS One ; 15(5): e0232529, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32357163

RESUMO

Electrical defibrillation is a well-established treatment for cardiac dysrhythmias. Studies have suggested that shock-induced spatial sawtooth patterns and virtual electrodes are responsible for defibrillation efficacy. We hypothesize that high-frequency shocks enhance defibrillation efficacy by generating temporal sawtooth patterns and using rapid virtual electrodes synchronized with shock frequency. High-speed optical mapping was performed on isolated rat hearts at 2000 frames/s. Two defibrillation electrodes were placed on opposite sides of the ventricles. An S1-S2 pacing protocol was used to induce ventricular tachyarrhythmia (VTA). High-frequency shocks of equal energy but varying frequencies of 125-1000 Hz were used to evaluate VTA vulnerability and defibrillation success rate. The 1000-Hz shock had the highest VTA induction rate in the shorter S1-S2 intervals (50 and 100 ms) and the highest VTA defibrillation rate (70%) among all frequencies. Temporal sawtooth patterns and synchronous shock-induced virtual electrode responses could be observed with frequencies of up to 1000 Hz. The improved defibrillation outcome with high-frequency shocks suggests a lower energy requirement than that of low-frequency shocks for successful ventricular defibrillation.


Assuntos
Cardioversão Elétrica/métodos , Taquicardia Ventricular/terapia , Fibrilação Ventricular/terapia , Animais , Modelos Animais de Doenças , Eletrodos , Fenômenos Eletrofisiológicos , Feminino , Ventrículos do Coração/fisiopatologia , Técnicas In Vitro , Modelos Cardiovasculares , Ratos , Ratos Sprague-Dawley , Taquicardia Ventricular/fisiopatologia , Interface Usuário-Computador , Fibrilação Ventricular/fisiopatologia , Função Ventricular , Imagens com Corantes Sensíveis à Voltagem/instrumentação , Imagens com Corantes Sensíveis à Voltagem/métodos
8.
Sci Rep ; 10(1): 8548, 2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32444634

RESUMO

The emergence of optical imaging has revolutionized the investigation of cardiac electrical activity and associated disorders in various cardiac pathologies. The electrical signals of the heart and the propagation pathways are crucial for elucidating the mechanisms of various cardiac pathological conditions, including arrhythmia. The synthesis of near-infrared voltage-sensitive dyes and the voltage sensitivity of the FDA-approved dye Cardiogreen have increased the importance of optical mapping (OM) as a prospective tool in clinical practice. We aimed to develop a method for the high-spatiotemporal-resolution OM of the large animal hearts in situ using di-4-ANBDQBS and Cardiogreen under patho/physiological conditions. OM was adapted to monitor cardiac electrical behaviour in an open-chest pig heart model with physiological or artificial blood circulation. We detail the methods and display the OM data obtained using di-4-ANBDQBS and Cardiogreen. Activation time, action potential duration, repolarization time and conduction velocity maps were constructed. The technique was applied to track cardiac electrical activity during regional ischaemia and arrhythmia. Our study is the first to apply high-spatiotemporal-resolution OM in the pig heart in situ to record cardiac electrical activity qualitatively under artificial blood perfusion. The use of an FDA-approved voltage-sensitive dye and artificial blood perfusion in a swine model, which is generally accepted as a valuable pre-clinical model, demonstrates the promise of OM for clinical application.


Assuntos
Corantes Fluorescentes/química , Coração/fisiologia , Modelos Cardiovasculares , Isquemia Miocárdica/fisiopatologia , Taquicardia Ventricular/fisiopatologia , Fibrilação Ventricular/fisiopatologia , Imagens com Corantes Sensíveis à Voltagem/métodos , Animais , Mapeamento Potencial de Superfície Corporal/métodos , Suínos
10.
Am J Cardiol ; 126: 37-44, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32336534

RESUMO

Differentiation of outflow tract ventricular arrhythmias (OT-VAs) which originate from the posterior right ventricular outflow tract (RVOT), right coronary cusp (RCC) or near the His-bundle are still a challenge until now. This study was aimed to develop a stepwise electrocardiogram (ECG) algorithm to distinguish their locations. Seventy-five consecutive patients with VAs successfully ablated from the posterior RVOT (n = 57), near the His-bundle (n = 5) or RCC (n = 13) were enrolled in our study. Measurements with highest diagnostic performance were chosen to develop a diagnostic algorithm. Of all these ECG measurements, the R-wave amplitude in lead I and V2S/V3R index showed the best diagnostic performance to discriminate these anatomical sites. The optimal ECG discriminators were different combination of lead I and V2S/V3R index as follows: the posterior RVOT, Lead I R-wave amplitude <0.65 mV and V2S/V3R index>1.5 (96.2% sensitivity, 69.6% specificity); the near the His-bundle, lead I R-wave amplitude ≥0.65 mV and V2S/V3R index>1.5 (100% sensitivity, 70% specificity); RCC, lead I R-wave amplitude<0.65 mV and V2S/V3R index ≤1.5 (52.9% sensitivity, 93.1% specificity). Sequential algorithmic application of these criteria resulted in an overall accuracy of 83% in predicting site of OT-VA origin. A predominantly positive R-wave in lead I is seen in OT-VAs originated near the His-bundle. A stepwise ECG algorithm of combination with R-wave amplitude in lead I and V2S/V3R index could localize the origins of OT-VAs from the posterior RVOT, near the His-bundle and the RCC with a high accuracy.


Assuntos
Algoritmos , Fascículo Atrioventricular/fisiopatologia , Eletrocardiografia , Ventrículos do Coração/fisiopatologia , Fibrilação Ventricular/fisiopatologia , Adulto , Fascículo Atrioventricular/cirurgia , Ablação por Cateter , Feminino , Ventrículos do Coração/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade , Fibrilação Ventricular/cirurgia
11.
Cardiovasc Drugs Ther ; 34(3): 323-334, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32297025

RESUMO

PURPOSE: To compare the effects of class III antiarrhythmic agents (amiodarone vs. ibutilide) on ventricular fibrillation (VF) and hemodynamic status in a canine heart failure (HF) model. METHODS: A total of 12 beagles were used to establish the HF model by rapid pacing for 4 consecutive weeks. These canines were randomly divided into two groups based on the administration of ibutilide and amiodarone. A 12 × 12 unipolar electrode plaque was used for ventricular epicardial mapping, and a 6-electrode plunge needle was inserted for ventricular transmural mapping. The restitution curve was estimated from activation recovery intervals (ARIs) by pacing from the plaque electrodes before and after drug administration. The defibrillation threshold (DFT) and VF activation patterns, including the activation rate, cycle length (VF-CL) and the transmural dispersion of the activation rate, were evaluated and the hemodynamic parameters were mearsured and compared before and after drug administration. RESULTS: Compared to HF baseline, ibutilide administration has markedly decreased the DFT by 28% (18 ± 2 J vs. 13 ± 2.7 J, P < 0.01) without affecting the canine's hemodynamics (mean arterial pressure 91 ± 15 mmHg vs. 92 ± 17 mmHg, P > 0.05). Furthermore, VF activation pattern became more organized, and spontaneous termination was observed only after ibutilide administration. Conversely, amiodarone has significantly compromised the hemodynamic status (mean arterial pressure 92 ± 6.1 mmHg vs. 52 ± 11.6 mmHg, P < 0.05), but did not alter the DFT (17 ± 2.3 J vs. 16 ± 2.0 J, P > 0.05). Compared to pre-medication, both ibutilide and amiodarone have significantly prolonged the VERP (178 ± 9.6 ms vs. 208 ± 8.9 ms, P < 0.05; 185 ± 10.5 ms vs. 202 ± 7.5 ms, P < 0.05, respectively) and reduced the dispersion of refractoriness, the maximal slope of restitution curve, and the epicardial dispersion during pacing. Additionally, both drugs have significantly increased the VF-CL and reduced the transmural dispersion of the VF activation rate. CONCLUSIONS: Ibutilide had potential antifibrillatory properties, which was shown by decreasing the DFT and organizing the VF activation in HF, and with no apparent impact on the hemodynamic status. In contrast, intravenous amiodarone administration demonstrated prominent negative effects on the hemodynamic status possibly by affecting the myocardial contractility before and after defibrillation but did not alter the DFT.


Assuntos
Amiodarona/farmacologia , Antiarrítmicos/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Frequência Cardíaca/efeitos dos fármacos , Sulfonamidas/farmacologia , Fibrilação Ventricular/prevenção & controle , Potenciais de Ação , Animais , Pressão Arterial , Modelos Animais de Doenças , Cães , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/fisiopatologia , Período Refratário Eletrofisiológico , Fatores de Tempo , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/fisiopatologia
12.
Circ Arrhythm Electrophysiol ; 13(5): e007669, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32281407

RESUMO

BACKGROUND: There is paucity of data regarding radiofrequency ablation for ventricular tachycardia (VT) in patients with cardiogenic shock and concomitant VT refractory to antiarrhythmic drugs on mechanical support. METHODS: Patients undergoing VT ablation at our center were enrolled in a prospectively maintained registry and screened for the current study (2010-2017). RESULTS: All 21 consecutive patients with cardiogenic shock and concomitant refractory ventricular arrhythmia undergoing bailout ablation due to inability to wean off mechanical support were included. Median age was 61 years, 86% were men, median left ventricular ejection fraction was 20%, 81% had ischemic cardiomyopathy, and PAINESD score was 18±5. The type of mechanical support in place before the procedure was intra-aortic balloon pump in 14 patients (67%), Impella CP in 2, extracorporeal membrane oxygenation in 2, extracorporeal membrane oxygenation and intra-aortic balloon pump in 2, and extracorporeal membrane oxygenation and Impella CP in 1. Endocardial voltage maps showed myocardial scar in 19 patients (90%). The clinical VTs were inducible in 13 patients (62%), whereas 6 patients had premature ventricular contraction-induced ventricular fibrillation/VT (29%), and VT could not be induced in 2 patients (9%). Activation mapping was possible in all 13 with inducible clinical VTs. Substrate modification was performed in 15 patients with scar (79%). After ablation and scar modification, the arrhythmia was noninducible in 19 patients (91%). Seventeen (81%) were eventually weaned off mechanical support successfully, but 6 (29%) died during the index admission from persistent cardiogenic shock. Patients who had ventricular arrhythmia and cardiogenic shock on presentation had a trend toward lower in-hospital mortality compared with those who presented with cardiogenic shock and later developed ventricular arrhythmia. CONCLUSIONS: Bailout ablation for refractory ventricular arrhythmia in cardiogenic shock allowed successful weaning from mechanical support in a large proportion of patients. Mortality remains high, but the majority of patients were discharged home and survived beyond 1 year.


Assuntos
Circulação Assistida , Ablação por Cateter , Oxigenação por Membrana Extracorpórea , Frequência Cardíaca , Choque Cardiogênico/terapia , Taquicardia Ventricular/terapia , Fibrilação Ventricular/terapia , Idoso , Antiarrítmicos/uso terapêutico , Circulação Assistida/efeitos adversos , Circulação Assistida/instrumentação , Circulação Assistida/mortalidade , Ablação por Cateter/efeitos adversos , Ablação por Cateter/mortalidade , Resistência a Medicamentos , Oxigenação por Membrana Extracorpórea/efeitos adversos , Oxigenação por Membrana Extracorpórea/instrumentação , Oxigenação por Membrana Extracorpórea/mortalidade , Feminino , Frequência Cardíaca/efeitos dos fármacos , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Recuperação de Função Fisiológica , Recidiva , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Choque Cardiogênico/diagnóstico , Choque Cardiogênico/mortalidade , Choque Cardiogênico/fisiopatologia , Volume Sistólico , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/mortalidade , Taquicardia Ventricular/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Fibrilação Ventricular/diagnóstico , Fibrilação Ventricular/mortalidade , Fibrilação Ventricular/fisiopatologia , Função Ventricular Esquerda
13.
Scand J Trauma Resusc Emerg Med ; 28(1): 27, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32276599

RESUMO

BACKGROUND: Treatment of arrhythmias evoked by accidental or therapeutic hypothermia and rewarming remains challenging. We aim to find an ECG-biomarker that can predict ventricular arrhythmias at temperatures occurring in therapeutic and accidental hypothermia. MAIN BODY: Evaluation of ECG-data from accidental and therapeutic hypothermia patients and experimental data on ECG and ventricular fibrillation (VF) threshold in hypothermic New Zealand White Rabbits. VF threshold was measured in rabbit hearts cooled to moderate (31 °C) and severe (17 °C) hypothermia. QRS-interval divided by corrected QT-interval (QTc) was calculated at same temperatures. Clinical QRS/QTc data were obtained after a systematic literature review. Rabbit QRS/QTc values correlated with risk for VF (correlation coefficient: 0.97). Human QRS/QTc values from hypothermic patients, showed similar correlation with risk for ventricular fibrillation in the experimental data (correlation coefficient: 1.00). CONCLUSIONS: These calculations indicate that QRS/QTc has potential as novel biomarker for predicting risk of hypothermia-induced cardiac arrest. Our findings apply both to victims of accidental hypothermia and to patients undergoing therapeutic hypothermia during surgery or after e.g. cardiac arrest.


Assuntos
Parada Cardíaca/diagnóstico , Hipotermia Induzida/efeitos adversos , Hipotermia/complicações , Fibrilação Ventricular/diagnóstico , Animais , Biomarcadores , Modelos Animais de Doenças , Eletrocardiografia , Feminino , Parada Cardíaca/etiologia , Parada Cardíaca/terapia , Humanos , Hipotermia/terapia , Masculino , Coelhos , Reaquecimento/efeitos adversos , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/fisiopatologia
15.
PLoS One ; 15(3): e0230214, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32168323

RESUMO

Several pathological conditions introduce spatial variations in the electrical properties of cardiac tissue. These variations occur as localized or distributed gradients in ion-channel functionality over extended tissue media. Electrical waves, propagating through such affected tissue, demonstrate distortions, depending on the nature of the ionic gradient in the diseased substrate. If the degree of distortion is large, reentrant activity may develop, in the form of rotating spiral (2d) and scroll (3d) waves of electrical activity. These reentrant waves are associated with the occurrence of lethal cardiac rhythm disorders, known as arrhythmias, such as ventricular tachycardia (VT) and ventricular fibrillation (VF), which are believed to be common precursors of sudden cardiac arrest. By using state-of-the-art mathematical models for generic, and ionically-realistic (human) cardiac tissue, we study the detrimental effects of these ionic gradients on electrical wave propagation. We propose a possible mechanism for the development of instabilities in reentrant wave patterns, in the presence of ionic gradients in cardiac tissue, which may explain how one type of arrhythmia (VT) can degenerate into another (VF). Our proposed mechanism entails anisotropic reduction in the wavelength of the excitation waves because of anisotropic variation in its electrical properties, in particular the action potential duration (APD). We find that the variation in the APD, which we induce by varying ion-channel conductances, imposes a spatial variation in the spiral- or scroll-wave frequency ω. Such gradients in ω induce anisotropic shortening of wavelength of the spiral or scroll arms and eventually leads to instabilitites.


Assuntos
Coração/fisiopatologia , Taquicardia Ventricular/fisiopatologia , Fibrilação Ventricular/fisiopatologia , Potenciais de Ação/fisiologia , Anisotropia , Simulação por Computador , Morte Súbita Cardíaca/patologia , Eletricidade , Eletrofisiologia/métodos , Humanos , Modelos Cardiovasculares
16.
BMC Cardiovasc Disord ; 20(1): 134, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32169057

RESUMO

BACKGROUND: The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to the transvenous implantable cardioverter defibrillator for the prevention of sudden cardiac death. Here, we report a rare case of refractoriness to an S-ICD after frequent therapies for ventricular fibrillation (VF) storms. CASE PRESENTATION: A 24-year-old man underwent a bout of syncope with vomiting and incontinence at home. He was brought to the emergency room and was witnessed to spontaneously go into VF successfully converted by external defibrillation. Previously, he was diagnosed with a type I Brugada electrocardiogram pattern by a pilsicainide administration test in another hospital. Although he had a family history of sudden cardiac death in 3 relatives, including his brother, he was followed closely without any therapies because he had never had an episode of syncope. He was implanted with an S-ICD without any trouble. Seven months later, frequent S-ICD shocks for VF storms occurred. His VF was controlled by using intravenous amiodarone, which was converted to an oral preparation. However, his VF recurred after another 2 months. The analysis of his S-ICD data revealed that 4 consecutive shock deliveries could not terminate his VF and the final shock delivered could fortunately terminate it because of a high defibrillation threshold test (DFT) due to an increasing shock impedance (64 to 90 Ω). First, we performed an epicardial Brugada syndrome ablation and subsequently replaced and repositioned the S-ICD lead from a left to a right parasternal site. After the re-implantation of the S-ICD, the DFT test improved to within normal range. According to the pathological analysis, infiltration of inflammatory cells and extensive fibrosis were confirmed in the subcutaneous tissue around the shock lead and S-ICD body. CONCLUSION: Frequent S-ICD shocks for VF storms might cause various pathological changes around the device and lead to a high DFT.


Assuntos
Síndrome de Brugada/cirurgia , Ablação por Cateter , Desfibriladores Implantáveis , Cardioversão Elétrica/efeitos adversos , Cardioversão Elétrica/instrumentação , Migração de Corpo Estranho/etiologia , Frequência Cardíaca , Fibrilação Ventricular/terapia , Síndrome de Brugada/diagnóstico , Síndrome de Brugada/fisiopatologia , Remoção de Dispositivo , Migração de Corpo Estranho/patologia , Humanos , Masculino , Recidiva , Falha de Tratamento , Fibrilação Ventricular/diagnóstico , Fibrilação Ventricular/fisiopatologia , Adulto Jovem
18.
PLoS One ; 15(3): e0229078, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32126115

RESUMO

Brugada syndrome (BS) is a genetic pathological condition associated with a high risk for sudden cardiac death (SCD). Ventricular depolarization disorders have been suggested as a potential electrophysiological mechanism associated with high SCD risk on patients with BS. This paper aims to characterize the dynamic changes of ventricular depolarization observed during physical exercise in symptomatic and asymptomatic BS patients. To this end, cardiac ventricular depolarization features were automatically extracted from 12-lead ECG recordings acquired during standardized exercise stress test in 110 BS patients, of whom 25 were symptomatic. Conventional parameters were evaluated, including QRS duration, R and S wave amplitudes ([Formula: see text], [Formula: see text]), as well as QRS morphological features, such as up-stroke and down-stroke slopes of the R and S waves ([Formula: see text], [Formula: see text] and [Formula: see text]). The effects of physical exercise and recovery on the dynamics of these markers were assessed in both BS populations. Features showing significantly different dynamics between the studied groups were used alone and in combination with the clinical characteristics of the patients in a logistic regression analysis. Results show larger changes in the second half of the QRS complex through [Formula: see text] and [Formula: see text] measured in the right precordial leads for asymptomatic patients, especially during recovery, when the vagal tone is more pronounced. Multivariate analysis involving both types of features resulted in a reduced model of three relevant features ([Formula: see text] in lead V2, Sex and heart rate recovery, HRR), which achieved a suitable discrimination performance between groups; sensitivity = 80% and specificity = 75% (AUC = 83%). However, after controlling the model for possible confounding factors, only one feature ([Formula: see text]) remained meaningful. This adjusted model significantly improved the overall discrimination performance by up to: sensitivity = 84% and specificity = 100% (AUC = 94%). The study highlights the importance of physical exercise test to unmask differentiated behaviors between symptomatic and asymptomatic BS patients through depolarization dynamic analysis. This analysis together with the obtained model may help to identify asymptomatic patients at low or high risk of future cardiac events, but it should be confirmed by further prospective studies.


Assuntos
Potenciais de Ação/fisiologia , Síndrome de Brugada/fisiopatologia , Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Fibrilação Ventricular/fisiopatologia , Adulto , Eletrocardiografia , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
19.
Cardiology ; 145(3): 130-135, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32015236

RESUMO

INTRODUCTION: Changes in electrocardiogram (ECG) parameters and the incidence of arrhythmic events in patients with fever-induced Brugada syndrome (BrS) remain unknown. OBJECTIVE: We aimed to investigate the effect of hyperthermia on the ECG pattern and the occurrence of fever-triggered arrhythmic events (FTAEs) in patients with fever-induced BrS. METHODS: We retrospectively analyzed a series of fever-induced BrS cases from January 1966 to November 2018. Clinical characteristics and ECG parameters were evaluated in the presence or absence of fever. RESULTS: Syncope and implantable cardioverter defibrillator implantation occurred more frequently in BrS patients with FTAEs than in patients without FTAEs. In BrS patients <16 years old, more arrhythmia events occurred in patients with FTAEs than in patients without FTAEs (p = 0.04). During follow-up, 2 patients in the FTAEs group suffered new malignant arrhythmic events. Compared to the afebrile state, the J point increased significantly in precordial leads V1, V2, and V3 during the febrile state (all p < 0.01). The corrected QTpeak intervals in V1 and V2 were significantly longer in the FTAEs group than in the non-FTAEs group (354.5 ± 37.0 vs. 334.3 ± 45.5 ms, p < 0.01 and 368.0 ± 43.4 vs. 330.9 ± 41.5 ms, p < 0.01, respectively). An increased corrected QT dispersion and a lengthened corrected Tpeak-Tend dispersion were also observed during fever. CONCLUSIONS: Fever may not only reveal BrS but also induce life-threatening arrhythmic events, especially in children and adolescents.


Assuntos
Síndrome de Brugada/complicações , Eletrocardiografia , Fibrilação Ventricular/etiologia , Adulto , Síndrome de Brugada/fisiopatologia , Desfibriladores Implantáveis , Feminino , Febre/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Síncope/etiologia , Fibrilação Ventricular/fisiopatologia
20.
BMC Cardiovasc Disord ; 20(1): 60, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024466

RESUMO

BACKGROUND: Malignant ventricular arrhythmia (VA) is the most common cause of death associated with acute myocardial infarction (MI). Recent studies have revealed direct involvement of the paraventricular nucleus (PVN) in the occurrence of VA. However, the underlying mechanisms remain incompletely understood. In this study, we investigated changes in the interleukin-6 (IL-6)-glycoprotein 130-signal transducer and activator of transcription 3 (STAT3) pathway in the PVN during acute MI and the effects of this pathway on ventricular stability. METHODS: Rats were divided into a control group, a MI group, a PVN-injected anti-IL-6 antibody group and a PVN-injected SC144 group to observe how IL-6 and its downstream glycoprotein 130-STAT3 pathway in the PVN affect ventricular stability. The left anterior descending coronary artery was ligated to induce MI. After that, an anti-IL-6 antibody and SC144 were injected into the PVNs of rats. All data are expressed as the mean ± SE and were analysed by ANOVA with a post hoc LSD test. p < 0.05 was considered to indicate statistical significance. RESULTS: After MI, the concentration of the inflammatory factor IL-6 increased, and its downstream glycoprotein 130-STAT3 pathway was activated in the PVN. After injection of MI rat PVNs with the anti-IL-6 antibody or glycoprotein 130 inhibitor (SC144), glutamate levels increased and γ-aminobutyric acid (GABA) levels decreased in the PVN. Plasma norepinephrine concentrations also increased after treatment, which increased the vulnerability to VA. CONCLUSIONS: In summary, IL-6 in the PVN exerts a protective effect in MI rats, and the glycoprotein 130-STAT3 pathway plays a key role in this process. We anticipate that our findings will provide new ideas for the prevention and treatment of arrhythmia after MI.


Assuntos
Receptor gp130 de Citocina/metabolismo , Frequência Cardíaca , Interleucina-6/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Fator de Transcrição STAT3/metabolismo , Fibrilação Ventricular/prevenção & controle , Função Ventricular Esquerda , Potenciais de Ação , Animais , Modelos Animais de Doenças , Ácido Glutâmico/metabolismo , Masculino , Infarto do Miocárdio/complicações , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/fisiopatologia , Norepinefrina/sangue , Núcleo Hipotalâmico Paraventricular/fisiopatologia , Ratos Sprague-Dawley , Transdução de Sinais , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/metabolismo , Fibrilação Ventricular/fisiopatologia , Ácido gama-Aminobutírico/metabolismo
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