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1.
Endocr J ; 67(6): 585-592, 2020 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-32115439

RESUMO

A 74-year-old man who had type 2 diabetes mellitus of a duration of 20 years was admitted for syncope after eating a high carbohydrate meal. Although he had had episodes of pallor or syncope after carbohydrate-rich meals, such as with large amounts of white rice, several times within a year and he had been taken to hospitals emergently, the etiology of these episodes had remained unclear despite his undergoing several studies. Studies did show severe orthostatic hypotension during the head-up tilt test and a decrease in the coefficient of variation of the R-R interval (CVR-R) on resting electrocardiogram, suggesting severe autonomic nervous dysfunction. Because of the episodes of syncope after eating a carbohydrate-rich meal, we investigated whether he had postprandial hypotension (PPH). The 75 g oral glucose tolerance test revealed a significant decrease in his postprandial blood pressure by about 40 mmHg, leading to the diagnosis of PPH. The carbohydrate-rich meal test induced syncope with systolic blood pressure under 40 mmHg. Then 150 mg caffeine was administered before a second carbohydrate-rich meal. The marked decline in postprandial blood pressure was suppressed and plasma noradrenaline levels were gradually increased over a period of 60 minutes. Caffeine could be useful for prevention of postprandial hypotension-related syncope.

2.
Int Heart J ; 60(5): 1206-1210, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31484877

RESUMO

A 7-year-old female suffering from syncope attacks and deafness was genetically diagnosed with Jervell and Lange-Nielsen syndrome (JLNS). A transvenous-designed shock lead and implantable cardioverter-defibrillator (ICD) were atypically implanted subcutaneously, because the patient's body was small. Six years after implantation, we confirmed the patient's eligibility for a subcutaneous ICD (S-ICD) based on electrocardiogram screening. The implanted ICD system was replaced with a new standard S-ICD system. Implantation of the S-ICD may be considered a reliable and safe option in young patients with JLNS, even if their electrocardiograms show remarkable prolongation of the QT interval and T-wave alternans.


Assuntos
Desfibriladores Implantáveis/efeitos adversos , Eletrocardiografia/métodos , Síndrome de Jervell-Lange Nielsen/diagnóstico , Síndrome de Jervell-Lange Nielsen/terapia , Canal de Potássio KCNQ1/genética , Criança , Remoção de Dispositivo/métodos , Feminino , Seguimentos , Predisposição Genética para Doença , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Linhagem , Retratamento , Síncope/diagnóstico , Síncope/etiologia , Síncope/terapia , Fatores de Tempo , Resultado do Tratamento
3.
J Cardiovasc Electrophysiol ; 30(4): 565-568, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30661277

RESUMO

INTRODUCTION: Early repolarization syndrome is a recently proposed condition characterized by an early repolarization pattern in the electrocardiogram (ECG) and ventricular fibrillation in the absence of structural heart abnormalities. Although some studies have suggested that early repolarization is associated with frequency of atrial fibrillation, the association of early repolarization with atrial fibrillation is not well known. HYPOTHESIS: Early repolarization indicates the substrate for atrial fibrillation in addition to that for ventricular fibrillation. METHOD: This study included 79 patients (57 men [72%]; age, 45 ± 12 years) aged less than 60 years who had paroxysmal lone atrial fibrillation and 395 age- and sex-matched healthy controls (patient:control ratio, 1:5). Patients who had structural heart disease, hypertension, diabetes, hyperthyroidism, history of successful resuscitation, or the Brugada type ECG were excluded. ECGs recorded during sinus rhythm were compared between patients with atrial fibrillation and healthy controls. RESULTS: Early repolarization in the inferior and/or lateral leads was more common in patients with atrial fibrillation (25%) than controls (10%; P = 0.001). The location and magnitude of early repolarization were similar between the two groups. Other electrocardiographic measurements were not different between the two groups. Among patients with atrial fibrillation, there was no difference in clinical characteristics including age at atrial fibrillation development, sex, and body mass index between patients with early repolarization and those without early repolarization. Electrocardiographic measurements were not different between patients with early repolarization and those without early repolarization. CONCLUSION: Early repolarization was associated with lone atrial fibrillation. Early repolarization may indicate increased susceptibility to atrial fibrillation.

4.
Int Heart J ; 60(1): 199-203, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30464133

RESUMO

A 60-year-old female with premature ventricular contractions (PVCs) originating from the bottom of the posteromedial papillary muscle of the left ventricle underwent radiofrequency catheter ablation (RFCA) using an irrigated-tip catheter. During ablation of the PVCs, a loud steam pop was observed. Intracardiac echocardiography (ICE) revealed a growing, hyperechogenic intramyocardial microbubble formation around the catheter tip. The formation disappeared slowly and completely, leaving an endocardial laceration without pericardial effusion. ICE imaging is valuable during a difficult RFCA procedure, because ICE reveals the exact anatomical position of the catheter and thus allows rapid evaluation of the occurrence of steam popping and any possible subsequent complication.


Assuntos
Ablação por Cateter/métodos , Ecocardiografia/métodos , Ventrículos do Coração/fisiopatologia , Músculos Papilares/fisiopatologia , Complexos Ventriculares Prematuros/diagnóstico , Cateteres Cardíacos , Ablação por Cateter/efeitos adversos , Feminino , Humanos , Pessoa de Meia-Idade , Complexos Ventriculares Prematuros/fisiopatologia , Complexos Ventriculares Prematuros/terapia
5.
Circ J ; 82(12): 3037-3043, 2018 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-30305485

RESUMO

BACKGROUND: The implantable cardioverter defibrillator (ICD) is a standard prevention therapy for patients at high risk for sudden cardiac death (SCD) due to life-threatening ventricular arrhythmia (VA), that is, ventricular fibrillation and ventricular tachycardia. However, clinical predictors of recurrent VA in secondary prevention ICD recipients with coronary artery disease (CAD) remain unknown. Methods and Results: We followed up 96 consecutive patients with CAD undergoing ICD implantation for secondary prevention of SCD. Long-term rates and clinical predictors of appropriate ICD therapy (ICD-Tx) for VA were analyzed. Appropriate ICD-Tx occurred in 41 (42.7%) patients during a median follow-up of 2.4 years (interquartile range, 0.9-6.1). These patients had significantly greater left ventricular end-diastolic diameter (62.3±1.3 vs. 54.6±1.1 mm, P<0.001), lower left ventricular ejection fraction (LVEF; 36.3±2.0% vs. 45.7±1.8%, P<0.001), and more incomplete revascularization (ICR; 70.7% vs. 45.5%, P=0.014) than those without appropriate ICD-Tx. Multivariable analysis showed that LVEF (hazards ratio [HR], 0.950; 95% CI: 0.925-0.975; P<0.001) and ICR (HR, 2.293; 95% CI: 1.133-4.637; P=0.021) were significant predictors of appropriate ICD-Tx for VA. CONCLUSIONS: Lower LVEF and ICR were independent predictors of recurrent VA in secondary prevention ICD recipients with CAD.


Assuntos
Doença da Artéria Coronariana , Desfibriladores Implantáveis , Volume Sistólico , Taquicardia Ventricular , Fibrilação Ventricular , Função Ventricular Esquerda , Idoso , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/fisiopatologia , Doença da Artéria Coronariana/terapia , Feminino , Seguimentos , Humanos , Masculino , Taquicardia Ventricular/complicações , Taquicardia Ventricular/fisiopatologia , Taquicardia Ventricular/terapia , Fibrilação Ventricular/complicações , Fibrilação Ventricular/fisiopatologia , Fibrilação Ventricular/terapia
8.
J Electrocardiol ; 50(3): 277-281, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28238302

RESUMO

BACKGROUND: Patients with repetitive ventricular tachyarrhythmias - so-called electrical storm - frequently require antiarrhythmic drugs. Amiodarone is widely used for the treatment of electrical storm but is ineffective in some patients. Therefore, we investigated the efficacy of stepwise administration of nifekalant, a pure potassium channel blocker, and mexiletine for electrical storm. METHODS: This study included 44 patients with repetitive ventricular tachyarrhythmias who received stepwise therapy with nifekalant and mexiletine for electrical storm. Nifekalant was initially administered, and mexiletine was subsequently added if nifekalant failed to control ventricular tachyarrhythmias. RESULTS: Nifekalant completely suppressed recurrences of ventricular arrhythmias in 28 patients (64%), including 6 patients in whom oral amiodarone failed to control arrhythmias. In 9 of 16 patients in whom nifekalant was partially effective but failed to suppress ventricular arrhythmias, mexiletine was added. The addition of mexiletine prevented recurrences of ventricular tachyarrhythmias in 5 of these 9 patients (56%). There was no death associated with electrical storm. In total, the stepwise treatment with nifekalant and mexiletine was effective in preventing ventricular tachyarrhythmias in 33 of 44 patients (75%). There was no difference in cycle length of the ventricular tachycardia, QRS interval, QT interval, or left ventricular ejection fraction between patients who responded to antiarrhythmic drugs and those who did not. During follow-up, 8 patients had repetitive ventricular tachyarrhythmia recurrences, and the stepwise treatment was effective in 6 of these 8 patients (75%). CONCLUSIONS: The stepwise treatment with nifekalant and mexiletine was highly effective in the suppression of electrical storm.


Assuntos
Eletroencefalografia/efeitos dos fármacos , Mexiletina/administração & dosagem , Bloqueadores dos Canais de Potássio/administração & dosagem , Pirimidinonas/administração & dosagem , Bloqueadores dos Canais de Sódio/administração & dosagem , Taquicardia Ventricular/tratamento farmacológico , Taquicardia Ventricular/mortalidade , Administração Oral , Humanos , Japão/epidemiologia , Prevalência , Recidiva , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida , Taquicardia Ventricular/diagnóstico , Resultado do Tratamento
9.
Biophys J ; 111(2): 438-451, 2016 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-27463145

RESUMO

Cardiac optical mapping uses potentiometric fluorescent dyes to image membrane potential (Vm). An important limitation of conventional optical mapping is that contraction is usually arrested pharmacologically to prevent motion artifacts from obscuring Vm signals. However, these agents may alter electrophysiology, and by abolishing contraction, also prevent optical mapping from being used to study coupling between electrical and mechanical function. Here, we present a method to simultaneously map Vm and epicardial contraction in the beating heart. Isolated perfused swine hearts were stained with di-4-ANEPPS and fiducial markers were glued to the epicardium for motion tracking. The heart was imaged at 750 Hz with a video camera. Fluorescence was excited with cyan or blue LEDs on alternating camera frames, thus providing a 375-Hz effective sampling rate. Marker tracking enabled the pixel(s) imaging any epicardial site within the marked region to be identified in each camera frame. Cyan- and blue-elicited fluorescence have different sensitivities to Vm, but other signal features, primarily motion artifacts, are common. Thus, taking the ratio of fluorescence emitted by a motion-tracked epicardial site in adjacent frames removes artifacts, leaving Vm (excitation ratiometry). Reconstructed Vm signals were validated by comparison to monophasic action potentials and to conventional optical mapping signals. Binocular imaging with additional video cameras enabled marker motion to be tracked in three dimensions. From these data, epicardial deformation during the cardiac cycle was quantified by computing finite strain fields. We show that the method can simultaneously map Vm and strain in a left-sided working heart preparation and can image changes in both electrical and mechanical function 5 min after the induction of regional ischemia. By allowing high-resolution optical mapping in the absence of electromechanical uncoupling agents, the method relieves a long-standing limitation of optical mapping and has potential to enhance new studies in coupled cardiac electromechanics.


Assuntos
Potenciais da Membrana , Contração Miocárdica , Pericárdio/fisiologia , Imagens com Corantes Sensíveis à Voltagem , Animais , Fenômenos Biomecânicos , Feminino , Masculino , Pericárdio/citologia , Suínos
10.
Heart Rhythm ; 13(8): 1707-15, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27136698

RESUMO

BACKGROUND: Catheter ablation of the renal artery can be performed without apparent angiographic stenosis. This suggests that renal nerve function can be attenuated with minor structural damage to the renal artery. OBJECTIVE: To clarify this hypothesis, we examined the relationship between electrical nerve stimulation (ENS)-induced blood pressure (BP) response and severity of histological injury of the renal artery using an acute canine model of renal artery ablation. METHODS: An irrigation catheter was inserted into the renal arteries of 8 dogs, and radiofrequency current was delivered at 15, 20, or 25 W. ENS was applied to each artery before and after ablation. RESULTS: Before ablation, ENS increased the BP and heart rate from 145 ± 15/86 ± 13 to 189 ± 21/111 ± 19 mm Hg and from 116 ± 9 to 130 ± 6 beats/min, respectively. Heart rate variability indices and serum catecholamine levels were elevated concomitantly. After ablation, the ENS-induced increase in BP and heart rate were markedly attenuated after 15 W ablation and those were nearly completely inhibited after 20 or 25 W ablation. An increase in heart rate variability indices and serum catecholamine levels became insignificant regardless of the applied energy. Renal artery angiograms revealed stenotic lesions only after 25 W ablation procedures. Histological studies showed mild to moderate injury of the arterial wall and autonomic nerves caused by 20 and 25 W ablation procedures, whereas only minor changes caused by 15 W ablation. CONCLUSION: Functional renal autonomic nerve ablation is potentially performable with the guidance of ENS.


Assuntos
Vias Autônomas/fisiopatologia , Ablação por Cateter/métodos , Hipertensão/cirurgia , Rim/inervação , Artéria Renal/cirurgia , Simpatectomia/métodos , Animais , Vias Autônomas/cirurgia , Modelos Animais de Doenças , Cães , Estimulação Elétrica , Hipertensão/fisiopatologia , Rim/irrigação sanguínea , Artéria Renal/inervação
11.
Intern Med ; 54(10): 1175-82, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25986253

RESUMO

OBJECTIVE: The dominant frequency (DF) in frequency analyses is considered to represent the objective cycle length and complexity of activation under conditions of ventricular fibrillation (VF). However, knowledge regarding the mechanisms determining the DF in human VF is limited. We studied the characteristics of the DF of human VF and relationship between DF and the defibrillation threshold. METHODS: Seventy-two implantable cardioverter-defibrillator patients and 211 VF were studied. Using defibrillation tests, we performed a frequency analysis with fast Fourier transformation. The correlations between DF and clinical characteristics, including the defibrillation threshold, were assessed. RESULTS: The mean DF of all induced VFs was 5.2±0.8 Hz. The patients were divided into two groups according to DF: the low-DF (DF <5.2 Hz, n=32) and high-DF (DF ≥5.2 Hz, n=40) groups. The frequency of structural heart disease was significantly higher in the low-DF group. In addition, the QRS duration, QT interval and effective refractory period of the right ventricle (RV-ERP) were significantly longer in the low-DF group. A multivariate analysis showed RV-ERP to be the only independent predictor of DF. Excluding patients receiving group III anti-arrhythmic drugs, which are known to have potent defibrillation threshold effects, the defibrillation threshold was significantly lower in the low-DF group (p=0.026). CONCLUSION: We found that the DF of human VF is associated with underlying heart disease, the cardiac function, cardiac conduction, ventricular refractoriness and defibrillation threshold. Our findings may be useful for identifying and managing patients with a high defibrillation threshold.


Assuntos
Desfibriladores Implantáveis , Fibrilação Ventricular/fisiopatologia , Fibrilação Ventricular/terapia , Adulto , Idoso , Antiarrítmicos/administração & dosagem , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fibrilação Ventricular/tratamento farmacológico , Adulto Jovem
12.
Hypertension ; 61(2): 450-6, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23283361

RESUMO

Radiofrequency (RF) catheter ablation of the renal artery is therapeutic in patients with drug-refractory essential hypertension. This study was designed to examine the role of the renal autonomic nerves and of RF application from inside the renal artery in the regulation of blood pressure (BP). An open irrigation catheter was inserted into either the left or right renal artery in 8 dogs. RF current (17 ± 2 watts) was delivered to one renal artery. Electrical autonomic nerve stimulation was applied to each renal artery before and after RF ablation. BP, heart rate, indices of heart rate variability, and serum catecholamines were analyzed. Before RF ablation, electrical autonomic nerve stimulation of either renal artery increased BP from 150 ± 16/92 ± 15 to 173 ± 21/105 ± 16 mm Hg. After RF ablation, BP increased similarly when the nonablated renal artery was electrically stimulated, although the rise in BP was attenuated when the ablated renal artery was stimulated. Serum catecholamines and sympathetic nerve indices of heart rate variability increased when electrical autonomic nerve stimulation was applied before RF ablation and to the nonablated renal artery after RF ablation, although it changed minimally when the ablated renal artery was stimulated, suggesting interconnectivity between afferent renal nerve stimulation and systemic sympathetic activity. Renal artery angiogram showed no apparent injury after RF ablation. In conclusion, electrical stimulation of the renal arterial autonomic nerves increases BP via an increase in central sympathetic nervous activity. This response might be used to determine the target ablation site and end point of renal artery RF ablation.


Assuntos
Sistema Nervoso Autônomo/fisiologia , Pressão Sanguínea/fisiologia , Estimulação Elétrica , Frequência Cardíaca/fisiologia , Artéria Renal/inervação , Animais , Catecolaminas/sangue , Ablação por Cateter , Cães , Artéria Renal/cirurgia
14.
Pacing Clin Electrophysiol ; 36(4): e115-9, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21208238

RESUMO

A 65-year-old recipient of an implantable cardioverter defibrillator suffering from ventricular noncompaction developed storms of ventricular tachycardia (VT). Epicardial voltage mapping revealed the presence of a large low-voltage area in the left ventricular apical and inferoposterior wall, and isolated delayed potential was recorded over 1.5 cm in the posterior border between low and normal myocardial voltage. Pacemapping at the delayed potential recording site produced two different QRS depending on pacing output strength, and these two QRS morphologies were similar to clinically documented VTs. During one of the VTs, a mid-diastolic potential was recorded from the site with the delayed potential, and rapid pacing produced concealed entrainment. After epicardial radiofrequency ablation of the isolated delayed potential, VTs were noninducible and the VT storm was suppressed.


Assuntos
Cardiomiopatias/fisiopatologia , Cardiomiopatias/cirurgia , Ablação por Cateter/métodos , Desfibriladores Implantáveis , Miocárdio Ventricular não Compactado Isolado/fisiopatologia , Miocárdio Ventricular não Compactado Isolado/cirurgia , Taquicardia Ventricular/fisiopatologia , Taquicardia Ventricular/cirurgia , Idoso , Angiografia Coronária , Eletrocardiografia , Humanos , Masculino , Pericárdio/cirurgia
15.
Intern Med ; 51(19): 2689-94, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23037457

RESUMO

BACKGROUND: The structures composing implantable cardioverter-defibrillator (ICD) leads have become more complicated and thinner with technological advances. Silicon insulation defects with and without clinically manifested electrical abnormalities have been reported in Riata leads (St. Jude Medical). OBJECTIVE: The aim of this study was to assess the incidence and clinical implications of insulation defects in Riata leads implanted at our hospital. METHODS: The subjects included 10 consecutive patients who received 8-French Riata ICD leads with dual-coil conductors (model 1580 or 1581) between 2006 and 2010 at our hospital. Operative records, chest X-rays and interrogation data were reviewed. RESULTS: In all cases, Atlas+ (St. Jude Medical) was used as an ICD generator and the Riata leads were implanted transvenously and fixed to the right ventricular apex. During a mean follow-up period of 52±9 (36-70) months, chest X-rays revealed insulation defects in Riata leads and conductor wires projecting from the bodies of the Riata leads in two of 10 (20%) patients. One of the patients received inappropriate ICD therapies due to T-wave oversensing based on attenuation of R waves and augmentation of T waves 41 months after implantation. In the other patient, an insulation defect without any clinically manifested electrical troubles was detected 50 months after implantation. CONCLUSION: Riata leads have a high incidence of insulation defects, which may be occasionally accompanied by inappropriate ICD discharges. For patients with Riata leads, careful observation of any changes in the lead-electrical measurements and a routine chest X-ray follow-up are necessary.


Assuntos
Desfibriladores Implantáveis/efeitos adversos , Falha de Prótese , Adulto , Idoso , Síndrome de Brugada/terapia , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Seguimentos , Humanos , Incidência , Japão , Masculino , Pessoa de Meia-Idade , Radiografia Torácica , Taquicardia Ventricular/terapia , Fatores de Tempo , Adulto Jovem
16.
Intern Med ; 51(14): 1857-60, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22821100

RESUMO

An 8-year-old boy suffered from an unconsciousness attack and torsade de pointes arrhythmia during sleep or at rest. His electrocardiogram showed prolonged QT intervals, but the T wave morphology was atypical for type 1, 2 or 3 congenital long-QT syndrome (LQTS). Intravenous epinephrine slightly prolonged the QT interval whereas mexiletine infusion shortened the QT interval. Although these clinical characteristics might suggest type 3 LQTS, a genetic analysis identified the G604S-KCNH2 mutation (type 2 LQTS). Because mismatches between the genotype and phenotype of LQTS are possible, genetic analysis of LQTS is important to identify the most appropriate therapeutic option and risk stratification.


Assuntos
Canais de Potássio Éter-A-Go-Go/genética , Síndrome do QT Longo/genética , Mutação de Sentido Incorreto , Criança , Canal de Potássio ERG1 , Eletrocardiografia , Epinefrina , Estudos de Associação Genética , Heterozigoto , Humanos , Síndrome do QT Longo/complicações , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/fisiopatologia , Masculino , Mexiletina , Sono , Torsades de Pointes/etiologia , Torsades de Pointes/genética , Torsades de Pointes/fisiopatologia
17.
Pacing Clin Electrophysiol ; 35(8): e239-42, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22433001

RESUMO

An asymptomatic 15-year-old boy, who had a family history of sudden cardiac death, was referred for screening for cardiac disease. The 12-lead electrocardiogram at rest showed a short QT/QTc(Bazett)/QTc(Fredericia) interval of 320/388/364 ms, but the intervals were further shortened to 200/339/284 ms after the treadmill test concomitant with appearance of a peaked T wave. Other conventional cardiac examinations were normal, but effective refractory period was less than 180 ms in both ventricles, and double ventricular extrastimulation reproducibly induced nonsustained polymorphic ventricular tachycardia. Intravenous administration of epinephrine also induced a short QT interval and a peaked T wave, and a hump was manifested on the T wave of the first postpacing beat with a longer preceding R-R interval. Furthermore, a couple of premature ventricular complexes originated from a similar timing as the hump. Genetic analysis did not show the mutation in KCNQ1, KCNH2, KCNE1, KCNE2, KCNJ2, SCN5A genes but revealed single nucleotide polymorphism (C5457T) in SCN5A gene.


Assuntos
Morte Súbita Cardíaca , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Taquicardia Ventricular/diagnóstico , Adolescente , Agonistas Adrenérgicos , Eletrocardiografia , Epinefrina , Teste de Esforço , Humanos , Masculino , Linhagem , Polimorfismo de Nucleotídeo Único , Taquicardia Ventricular/genética , Complexos Ventriculares Prematuros/diagnóstico
18.
Europace ; 14(5): 715-23, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22037542

RESUMO

AIMS: The aim of this study was to investigate the relationship between J-wave dynamics and arrhythmias during myocardial ischaemia in patients with vasospastic angina (VSA). METHODS AND RESULTS: Sixty-seven consecutive patients diagnosed with VSA by a provocation test for coronary spasm were grouped according to whether they had a J wave in the baseline electrocardiograms or not (VSA-JW group, n = 14; VSA-non-JW group: n = 53). We retrospectively studied the associations between J-wave and ST-segment dynamics and induced ventricular fibrillations (VFs) during coronary spasm.  In the VSA-JW group, 7 of the 14 patients showed changes in J-wave morphology and/or gains in J-wave voltage, followed by VF in 4 patients. Compared with patients without VF, the four patients with VF showed similar maximal voltage in the baseline J waves but a higher voltage during induced coronary spasms (0.57 ± 0.49 vs. 0.30 ± 0.11 mV; P = 0.011). In three patients with VF, J waves progressively increased and were accompanied by the characteristic coved-type or lambda-shaped ST-segment elevations. In the VSA-non-JW group, only four patients showed new appearances of J waves during coronary spasms and another patient without a distinct J wave developed VF. Ventricular fibrillations were induced more frequently in the VSA-JW group than in the VSA-non-JW group [4/14 (29%) vs. 1/53 (2%); P = 0.012]. CONCLUSION: J-wave augmentations were caused by myocardial ischaemia during coronary spasms. The presence and augmentation of J waves, especially prominent J waves with the characteristic ST-elevation patterns, were associated with VF.


Assuntos
Angina Pectoris/fisiopatologia , Vasoespasmo Coronário/fisiopatologia , Eletrocardiografia/métodos , Isquemia Miocárdica/fisiopatologia , Fibrilação Ventricular/fisiopatologia , Acetilcolina , Adulto , Idoso , Angina Pectoris/diagnóstico , Vasoespasmo Coronário/induzido quimicamente , Vasoespasmo Coronário/diagnóstico , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/diagnóstico , Estudos Retrospectivos , Vasodilatadores , Fibrilação Ventricular/diagnóstico
19.
Heart Rhythm ; 9(5): 796-803, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22123313

RESUMO

BACKGROUND: Previous studies have showed that the interval between the peak and the end of the T wave (Tp-e) is a marker of transmural dispersion of ventricular repolarization. OBJECTIVE: We studied the relationship between (a) the Tp-e on local pseudo transmural electrograms (pseudo transmural Tp-e) or limb leads of body surface electrocardiogram (surface Tp-e) and (b) the intracardiac left ventricular (LV) repolarization during a drug-induced QT-interval prolongation. METHODS: Using open-chested canine intact hearts treated by anthopleurin-A, transmural LV electrograms were recorded via needle electrodes placed in the basoanterior, midanterior, apicoanterior, basolateral, midlateral, and apicolateral LV wall. Recovery time (RT) was calculated as an index of local repolarization at each transmural unipolar electrode. RESULTS: This model showed slower heart rate-dependent heterogeneous distribution of ventricular repolarization both along the basal to apical axis and along the transmural axis. RT was longer at the LV apex than at the base and longer in the lateral than in the anterior wall during the slower heart rate. A high correlation was found between surface Tp-e and total LV dispersion. In contrast, pseudo transmural Tp-e correlated with transmural RT dispersion. The shortest RT in the heart roughly corresponded to the peak, as did the longest RT with the end of the T wave on the surface electrocardiogram. CONCLUSION: During drug-induced QT-interval prolongation with a large apicobasal and anterolateral dispersion of ventricular repolarization, the Tp-e in the limb leads expresses spatial (total) distribution of repolarization in the whole left ventricle.


Assuntos
Eletrocardiografia , Sistema de Condução Cardíaco/fisiopatologia , Ventrículos do Coração/fisiopatologia , Síndrome do QT Longo/fisiopatologia , Animais , Cães , Eletrodos Implantados , Peptídeos e Proteínas de Sinalização Intercelular , Síndrome do QT Longo/induzido quimicamente , Peptídeos
20.
Europace ; 14(5): 675-81, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22158850

RESUMO

AIM: The aim of this study was to determine whether or not the coexistence of sustained ST-segment elevation and abnormal Q waves (STe-Q) could be a risk factor for electrical storm (ES) in implanted cardioverter defibrillator (ICD) patients with structural heart diseases. METHODS AND RESULTS: In all, 156 consecutive patients received ICD therapy for secondary prevention of sudden cardiac death and/or sustained ventricular tachyarrhythmias were included. Electrical storm was defined as ≥3 separate episodes of ventricular tachycardia (VT) and/or ventricular fibrillation (VF) terminated by ICD therapies within 24 h. During a mean follow-up of 1825 ± 1188 days, 42 (26.9%) patients experienced ES, of whom 12 had coronary artery disease, 15 had idiopathic dilated cardiomyopathy, 6 had hypertrophic cardiomyopathy, 4 had arrhythmogenic right ventricular cardiomyopathy, 4 had cardiac sarcoidosis, and 1 had valvular heart disease. Sustained ST-segment elevation and abnormal Q waves in ≥2 leads on the 12-lead electrocardiography was observed in 33 (21%) patients. On the Kaplan-Meier analysis, patients with STe-Q had a markedly higher risk of ES than those without STe-Q (P< 0.0001). The multivariate Cox proportional hazards regression model indicated that STe-Q and left ventricular ejection fraction (LVEF) (<30%) were independent risk factors associated with the recurrence of VT/VF (STe-Q: HR 1.962, 95% CI 1.24-3.12, P= 0.004; LVEF: HR 1.860, 95% CI 1.20-2.89, P= 0.006), and STe-Q was an independent risk factor associated with ES (HR 4.955, 95% CI 2.69-9.13, P< 0.0001). CONCLUSION: Sustained ST-segment elevation and abnormal Q waves could be a risk factor of not only recurrent VT/VF but also ES in patients with structural heart diseases.


Assuntos
Cardiomiopatia Dilatada/epidemiologia , Desfibriladores Implantáveis/efeitos adversos , Hipertrofia Ventricular Esquerda/epidemiologia , Síndrome do Nó Sinusal/epidemiologia , Síndrome do Nó Sinusal/terapia , Taquicardia Ventricular/epidemiologia , Idoso , Displasia Arritmogênica Ventricular Direita/diagnóstico por imagem , Displasia Arritmogênica Ventricular Direita/epidemiologia , Estimulação Cardíaca Artificial/efeitos adversos , Estimulação Cardíaca Artificial/estatística & dados numéricos , Cardiomiopatia Dilatada/diagnóstico por imagem , Desfibriladores Implantáveis/estatística & dados numéricos , Eletrocardiografia/estatística & dados numéricos , Feminino , Seguimentos , Bloqueio Cardíaco/epidemiologia , Bloqueio Cardíaco/terapia , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Ventriculografia com Radionuclídeos , Fatores de Risco , Sarcoidose/epidemiologia , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/etiologia , Fibrilação Ventricular/diagnóstico , Fibrilação Ventricular/epidemiologia , Fibrilação Ventricular/etiologia
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