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1.
Eur Heart J ; 37(24): 1910-9, 2016 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-27147610

RESUMO

BACKGROUND: Microvascular obstruction (MVO) following primary percutaneous coronary intervention (PPCI) treatment of ST-segment elevation myocardial infarction (STEMI) contributes to infarct expansion, left ventricular (LV) remodelling, and worse clinical outcomes. The REFLO-STEMI trial tested whether intra-coronary (IC) high-dose adenosine or sodium nitroprusside (SNP) reduce infarct size and/or MVO determined by cardiac magnetic resonance (CMR). METHODS AND RESULTS: REFLO-STEMI, a prospective, open-label, multi-centre trial with blinded endpoints, randomized (1:1:1) 247 STEMI patients with single vessel disease presenting within 6 h of symptom onset to IC adenosine (2-3 mg total) or SNP (500 µg total) immediately following thrombectomy and again following stenting, or to standard PPCI. The primary endpoint was infarct size % LV mass (%LVM) on CMR undertaken 24-96 h after PPCI (n = 197). Clinical follow-up was to 6 months. There was no significant difference in infarct size (%LVM, median, interquartile range, IQR) between adenosine (10.1, 4.7-16.2), SNP (10.0, 4.2-15.8), and control (8.3, 1.9-14.0), P = 0.062 and P = 0.160, respectively, vs. CONTROL: MVO (% LVM, median, IQR) was similar across groups (1.0, 0.0-3.7, P = 0.205 and 0.6, 0.0-2.4, P = 0.244 for adenosine and SNP, respectively, vs. control 0.3, 0.0-2.8). On per-protocol analysis, infarct size (%LV mass, 12.0 vs. 8.3, P = 0.031), major adverse cardiac events (hazard ratio, HR, 5.39 [1.18-24.60], P = 0.04) at 30 days and 6 months (HR 6.53 [1.46-29.2], P = 0.01) were increased and ejection fraction reduced (42.5 ± 7.2% vs. 45.7 ± 8.0%, P = 0.027) in adenosine-treated patients compared with control. CONCLUSIONS: High-dose IC adenosine and SNP during PPCI did not reduce infarct size or MVO measured by CMR. Furthermore, adenosine may adversely affect mid-term clinical outcome. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01747174; https://clinicaltrials.gov/ct2/show/NCT01747174.


Assuntos
Intervenção Coronária Percutânea , Infarto do Miocárdio com Supradesnível do Segmento ST , Humanos , Imageamento por Ressonância Magnética , Estudos Prospectivos , Trombectomia , Resultado do Tratamento
2.
J Electrocardiol ; 44(4): 425-31, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21704220

RESUMO

BACKGROUND: For the assessment of patients with chest pain, the 12-lead electrocardiogram (ECG) is the initial investigation. Major management decisions are based on the ECG findings, both for attempted coronary artery revascularization and risk stratification. The aim of this study was to determine if the current 6 precordial leads (V(1)-V(6)) are optimally located for the detection of ST-segment elevation in ST-segment elevation myocardial infarction (STEMI). METHODS: We analyzed 528 (38% anterior [200], 44% inferior [233], and 18% lateral [95]) patients with STEMI with both a 12-lead ECG and an 80-lead body surface map (BSM) ECG (Prime ECG, Heartscape Technologies, Bangor, Northern Ireland). Body surface map was recorded within 15 minutes of the 12-lead ECG during the acute event and before revascularization. ST-segment elevation of each lead on the BSM was compared with the corresponding 12-lead precordial leads (V(1)-V(6)) for anterior STEMI. In addition, for lateral STEMI, leads I and aVL of the BSM were also compared; and limb leads II, III, aVF of the BSM were compared with inferior unipolar BSM leads for inferior STEMI. Leads with the greatest mean ST-segment elevation were selected, and significance was determined by analysis of variance of the mean ST segment. RESULTS: For anterior STEMI, leads V(1), V(2), 32, 42, 51, and 57 had the greatest mean ST elevation. These leads are located in the same horizontal plane as that of V(1) and V(2). Lead 32 had a significantly greater mean ST elevation than the corresponding precordial lead V(3) (P = .012); and leads 42, 51, and 57 were also significantly greater than corresponding leads V(4), V(5), V(6), respectively (P < .001). Similar findings were also found for lateral STEMI. For inferior STEMI, the limb leads of the BSM (II, III, and aVF) had the greatest mean ST-segment elevation; and lead III was significantly superior to the inferior unipolar leads (7, 17, 27, 37, 47, 55, and 61) of the BSM (P < .001). CONCLUSION: Leads placed on a horizontal strip, in line with leads V(1) and V(2), provided the optimal placement for the diagnosis of anterior and lateral STEMI and appear superior to leads V(3), V(4), V(5), and V(6). This is of significant clinical interest, not only for ease and replication of lead placement but also may lead to increased recruitment of patients eligible for revascularization with none or borderline ST-segment elevation on the initial 12-lead ECG.


Assuntos
Eletrocardiografia/instrumentação , Infarto do Miocárdio/diagnóstico , Idoso , Análise de Variância , Mapeamento Potencial de Superfície Corporal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/fisiopatologia , Estudos Retrospectivos
3.
Crit Care Med ; 38(2): 510-7, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19864942

RESUMO

OBJECTIVE: To assess the impedance cardiogram recorded by an automated external defibrillator during cardiac arrest to facilitate emergency care by lay persons. Lay persons are poor at emergency pulse checks (sensitivity 84%, specificity 36%); guidelines recommend they should not be performed. The impedance cardiogram (dZ/dt) is used to indicate stroke volume. Can an impedance cardiogram algorithm in a defibrillator determine rapidly circulatory arrest and facilitate prompt initiation of external cardiac massage? DESIGN: Clinical study. SETTING: University hospital. PATIENTS: Phase 1 patients attended for myocardial perfusion imaging. Phase 2 patients were recruited during cardiac arrest. This group included nonarrest controls. INTERVENTIONS: The impedance cardiogram was recorded through defibrillator/electrocardiographic pads oriented in the standard cardiac arrest position. MEASUREMENTS AND MAIN RESULTS: Phase 1: Stroke volumes from gated myocardial perfusion imaging scans were correlated with parameters from the impedance cardiogram system (dZ/dt(max) and the peak amplitude of the Fast Fourier Transform of dZ/dt between 1.5 Hz and 4.5 Hz). Multivariate analysis was performed to fit stroke volumes from gated myocardial perfusion imaging scans with linear and quadratic terms for dZ/dt(max) and the Fast Fourier Transform to identify significant parameters for incorporation into a cardiac arrest diagnostic algorithm. The square of the peak amplitude of the Fast Fourier Transform of dZ/dt was the best predictor of reduction in stroke volumes from gated myocardial perfusion imaging scans (range = 33-85 mL; p = .016). Having established that the two pad impedance cardiogram system could detect differences in stroke volumes from gated myocardial perfusion imaging scans, we assessed its performance in diagnosing cardiac arrest. Phase 2: The impedance cardiogram was recorded in 132 "cardiac arrest" patients (53 training, 79 validation) and 97 controls (47 training, 50 validation): the diagnostic algorithm indicated cardiac arrest with sensitivities and specificities (+/- exact 95% confidence intervals) of 89.1% (85.4-92.1) and 99.6% (99.4-99.7; training) and 81.1% (77.6-84.3) and 97% (96.7-97.4; validation). CONCLUSIONS: The impedance cardiogram algorithm is a significant marker of circulatory collapse. Automated defibrillators with an integrated impedance cardiogram could improve emergency care by lay persons, enabling rapid and appropriate initiation of external cardiac massage.


Assuntos
Cardiografia de Impedância/normas , Desfibriladores/normas , Parada Cardíaca/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Débito Cardíaco , Eletrocardiografia , Feminino , Parada Cardíaca/diagnóstico , Massagem Cardíaca/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Imagem de Perfusão do Miocárdio , Sensibilidade e Especificidade , Volume Sistólico/fisiologia
4.
J Electrocardiol ; 42(6): 527-33, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19631334

RESUMO

The 3-phase time-sensitive model by Weisfeldt and Becker in 2002 has resulted in a redirection of efforts toward developing treatment algorithms specific to each phase of cardiac arrest. In this study, a number of physiologic indicators of ventricular fibrillation (VF) duration were investigated. The bispectral index was recorded at 15-second intervals over 12 minutes and recordings of the atrial electrocardiogram and lead II electrocardiogram were acquired simultaneously using Notocord data acquisition software during sinus rhythm, ventricular tachycardia, and VF, and analyzed using a total of 30 porcine models. A number of frequency markers (fast Fourier transform and density and amplitude of peaks [DA]) were derived. There was a direct relationship between VF duration and bispectral index with a Pearson correlation coefficient (mean) of r = -0.91. The P-P interval recorded in the atria during VF, demonstrated similar findings (r = 0.97) when measured against VF duration. It was interesting to note that P waves were still apparent during VF despite the on-going chaotic activity in the ventricles. The DA was calculated for each episode of prolonged VF and an exponential relationship with VF duration was observed. The dominant frequency during VF, DA, the P-P interval, and the BIS index are all potential physiologic indicators of VF duration.


Assuntos
Algoritmos , Diagnóstico por Computador/métodos , Eletrocardiografia/métodos , Frequência Cardíaca , Fibrilação Ventricular/diagnóstico , Animais , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Suínos
5.
Crit Care Med ; 36(5): 1578-84, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18434896

RESUMO

OBJECTIVE: Laypersons are poor at emergency pulse checks (sensitivity 84%, specificity 36%). Guidelines indicate that pulse checks should not be performed. The impedance cardiogram (dZ/dt) is used to assess stroke volume. Can a novel defibrillator-based impedance cardiogram system be used to distinguish between circulatory arrest and other collapse states? DESIGN: Animal study. SETTING: University research laboratory. SUBJECTS: Twenty anesthetized, mechanically ventilated pigs, weight 50-55 kg. INTERVENTIONS: Stroke volume was altered by right ventricular pacing (160, 210, 260, and 305 beats/min). Cardiac arrest states were then induced: ventricular fibrillation (by rapid ventricular pacing) and, after successful defibrillation, pulseless electrical activity and asystole (by high-dose intravenous pentobarbitone). MEASUREMENTS AND MAIN RESULTS: The impedance cardiogram was recorded through electrocardiogram/defibrillator pads in standard cardiac arrest positions. Simultaneously recorded electro- and impedance cardiogram (dZ/dt) along with arterial blood pressure tracings were digitized during each pacing and cardiac arrest protocol. Five-second epochs were analyzed for sinus rhythm (20 before ventricular fibrillation, 20 after successful defibrillation), ventricular fibrillation (40), pulseless electrical activity (20), and asystole (20), in two sets of ten pigs (ten training, ten validation). Standard impedance cardiogram variables were noncontributory in cardiac arrest, so the fast Fourier transform of dZ/dt was assessed. During ventricular pacing, the peak amplitude of fast Fourier transform of dZ/dt (between 1.5 and 4.5 Hz) correlated with stroke volume (r2 = .3, p < .001). In cardiac arrest, a peak amplitude of fast Fourier transform of dZ/dt of < or = 4 dB x ohm x rms indicated no output with high sensitivity (94% training set, 86% validation set) and specificity (98% training set, 90% validation set). CONCLUSIONS: As a powerful clinical marker of circulatory collapse, the fast Fourier transformation of dZ/dt (impedance cardiogram) has the potential to improve emergency care by laypersons using automated defibrillators.


Assuntos
Desfibriladores , Eletrocardiografia , Parada Cardíaca/diagnóstico , Animais , Impedância Elétrica , Eletrocardiografia/instrumentação , Feminino , Parada Cardíaca/fisiopatologia , Masculino , Suínos
6.
Am J Cardiol ; 98(5): 591-6, 2006 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-16923442

RESUMO

Epicardial electrical events were reconstructed using an inverse model for left ventricular (LV) pacing and during ventricular tachycardia (VT) induced during implantation of a biventricular pacemaker and/or internal defibrillator. The electrocardiographic position of the pacing lead, determined from the region of most negative potential 30 ms after the pacing spike, was compared with the radiographic position. Activation characterized by isochronal maps was correlated with the echocardiographic/myocardial scintigraphic data. Reconstructed epicardial isopotential/isochronal maps during VT were used to determine the presence of reentry. In 7 patients during LV pacing, epicardial isopotential maps located the maximum negative potentials anterolaterally (n = 3), posterolaterally (n = 2), and posteriorly (n = 2). Isochronal maps demonstrated activation patterns including regions of delayed activation that, in 5 patients, correlated with areas of akinesia/hypokinesia or fixed defects on echocardiography/myocardial scintigraphy. The mean difference between the radiographically measured right ventricular to LV pacing lead distance and calculated electrocardiographic right ventricular to LV pacing site distance was 1.7 cm. During VT, induced in 5 patients, single-loop reentry was observed in 3 and figure-of-8 reentry in 2. Exit site and regions of fast/slow conduction and conduction block that correlated with anatomic areas of infarction defined by echocardiography/myocardial scintigraphy were demonstrated. In conclusion, epicardial maps reconstructed from the body surface map can identify LV pacing sites and demonstrate reentry during VT. The body surface map could thus identify optimal pacing sites for LV pacing and targets for VT ablation.


Assuntos
Mapeamento Potencial de Superfície Corporal , Estimulação Cardíaca Artificial/métodos , Doença das Coronárias/complicações , Taquicardia Ventricular/fisiopatologia , Disfunção Ventricular Esquerda/complicações , Idoso , Doença das Coronárias/fisiopatologia , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Taquicardia Ventricular/complicações , Taquicardia Ventricular/terapia , Disfunção Ventricular Esquerda/fisiopatologia
7.
Circulation ; 108(2): 135-42, 2003 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12847070

RESUMO

BACKGROUND: The combination of a single-bolus fibrinolytic and a low-molecular-weight heparin may facilitate prehospital reperfusion and further improve clinical outcome in patients with ST-elevation myocardial infarction. METHODS AND RESULTS: In the prehospital setting, 1639 patients with ST-elevation myocardial infarction were randomly assigned to treatment with tenecteplase and either (1) intravenous bolus of 30 mg enoxaparin (ENOX) followed by 1 mg/kg subcutaneously BID for a maximum of 7 days or (2) weight-adjusted unfractionated heparin (UFH) for 48 hours. The median treatment delay was 115 minutes after symptom onset (53% within 2 hours). ENOX tended to reduce the composite of 30-day mortality or in-hospital reinfarction, or in-hospital refractory ischemia to 14.2% versus 17.4% for UFH (P=0.080), although there was no difference for this composite end point plus in-hospital intracranial hemorrhage or major bleeding (18.3% versus 20.3%, P=0.30). Correspondingly, there were reductions in in-hospital reinfarction (3.5% versus 5.8%, P=0.028) and refractory ischemia (4.4% versus 6.5%, P=0.067) but increases in total stroke (2.9% versus 1.3%, P=0.026) and intracranial hemorrhage (2.20% versus 0.97%, P=0.047). The increase in intracranial hemorrhage was seen in patients >75 years of age. CONCLUSIONS: Prehospital fibrinolysis allows 53% of patients to receive reperfusion treatment within 2 hours after symptom onset. The combination of tenecteplase with ENOX reduces early ischemic events, but lower doses of ENOX need to be tested in elderly patients. At present, therefore, tenecteplase and UFH are recommended as the routine pharmacological reperfusion treatment in the prehospital setting.


Assuntos
Serviços Médicos de Emergência/métodos , Enoxaparina/uso terapêutico , Heparina/uso terapêutico , Infarto do Miocárdio/tratamento farmacológico , Terapia Trombolítica/métodos , Ativador de Plasminogênio Tecidual/uso terapêutico , Idoso , Estudos de Coortes , Quimioterapia Combinada , Serviços Médicos de Emergência/estatística & dados numéricos , Enoxaparina/efeitos adversos , Feminino , Hemorragia/etiologia , Heparina/efeitos adversos , Humanos , Injeções Intravenosas , Injeções Subcutâneas , Masculino , Pessoa de Meia-Idade , Risco , Segurança , Análise de Sobrevida , Tenecteplase , Terapia Trombolítica/efeitos adversos , Fatores de Tempo , Ativador de Plasminogênio Tecidual/efeitos adversos , Resultado do Tratamento
8.
Circulation ; 101(23): 2690-5, 2000 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-10851205

RESUMO

BACKGROUND: We evaluated platelet activation and aggregation in patients with acute myocardial infarction (AMI) treated with thrombolytic therapy alone or with reduced-dose thrombolysis and concomitant abciximab. METHODS AND RESULTS: The study was performed in 20 control subjects and 51 patients with AMI before and after reperfusion with either alteplase or reteplase or reduced doses of these agents with concomitant abciximab. Platelet activation was assayed by platelet surface expression of P-selectin. Turbidometric platelet aggregation in response to ADP was measured in patients before thrombolytic therapy and 90 minutes and 24 hours after the beginning of thrombolytic therapy. P-selectin expression was greater at baseline in patients than normal control subjects (30.4% versus 9. 8%, P<0.0001) but was identical between the 2 groups after stimulation with ADP (64.4% versus 69.3%, P=0.37). However, at 24 hours, basal P-selectin expression declined in patients (P=0.0025 versus baseline), whereas ADP-stimulated P-selectin expression was lower in patients than in control subjects (48% versus 69%, P=0. 0004). When combined with reduced doses of either alteplase or reteplase, abciximab achieved 91% and 83% inhibition of 5 and 20 micromol/L ADP-induced platelet aggregation, which decreased to 46% and 40%, respectively, at 24 hours. No appreciable difference in the platelet inhibition profile of abciximab was observed between the 2 thrombolytics. CONCLUSIONS: Platelet activation and aggregation are heightened in the setting of thrombolysis for AMI. Despite this enhanced level of platelet activation, abciximab, combined with a reduced-dose thrombolytic, inhibited platelet aggregation similarly to the level reported in elective settings.


Assuntos
Anticorpos Monoclonais/administração & dosagem , Fragmentos Fab das Imunoglobulinas/administração & dosagem , Infarto do Miocárdio/tratamento farmacológico , Ativadores de Plasminogênio/administração & dosagem , Inibidores da Agregação Plaquetária/administração & dosagem , Agregação Plaquetária/efeitos dos fármacos , Terapia Trombolítica , Ativador de Plasminogênio Tecidual/administração & dosagem , Abciximab , Idoso , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Angiografia Coronária , Feminino , Fibrinolíticos/administração & dosagem , Humanos , Masculino , Pessoa de Meia-Idade , Selectina-P/biossíntese , Proteínas Recombinantes/administração & dosagem , Resultado do Tratamento
9.
Circulation ; 99(21): 2720-32, 1999 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-10351964

RESUMO

BACKGROUND: The TIMI 14 trial tested the hypothesis that abciximab, the Fab fragment of a monoclonal antibody directed to the platelet glycoprotein (GP) IIb/IIIa receptor, is a potent and safe addition to reduced-dose thrombolytic regimens for ST-segment elevation MI. METHODS AND RESULTS: Patients (n=888) with ST-elevation MI presenting <12 hours from onset of symptoms were treated with aspirin and randomized initially to either 100 mg of accelerated-dose alteplase (control) or abciximab (bolus 0.25 mg/kg and 12-hour infusion of 0.125 microg. kg-1. min-1) alone or in combination with reduced doses of alteplase (20 to 65 mg) or streptokinase (500 000 U to 1.5 MU). Control patients received standard weight-adjusted heparin (70-U/kg bolus; infusion of 15 U. kg-1. h-1), whereas those treated with a regimen including abciximab received low-dose heparin (60-U/kg bolus; infusion of 7 U. kg-1. h-1). The rate of TIMI 3 flow at 90 minutes for patients treated with accelerated alteplase alone was 57% compared with 32% for abciximab alone and 34% to 46% for doses of streptokinase between 500 000 U and 1.25 MU with abciximab. Higher rates of TIMI 3 flow at both 60 and 90 minutes were observed with increasing duration of administration of alteplase, progressing from a bolus alone to a bolus followed by either a 30- or 60-minute infusion (P<0.02). The most promising regimen was 50 mg of alteplase (15-mg bolus; infusion of 35 mg over 60 minutes), which produced a 76% rate of TIMI 3 flow at 90 minutes and was tested subsequently in conjunction with either low-dose or very-low-dose (30-U/kg bolus; infusion of 4 U. kg-1. h-1) heparin. TIMI 3 flow rates were significantly higher in the 50-mg alteplase plus abciximab group versus the alteplase-only group at both 60 minutes (72% versus 43%; P=0.0009) and 90 minutes (77% versus 62%; P=0.02). The rates of major hemorrhage were 6% in patients receiving alteplase alone (n=235), 3% with abciximab alone (n=32), 10% with streptokinase plus abciximab (n=143), 7% with 50 mg of alteplase plus abciximab and low-dose heparin (n=103), and 1% with 50 mg of alteplase plus abciximab with very-low-dose heparin (n=70). CONCLUSIONS: Abciximab facilitates the rate and extent of thrombolysis, producing early, marked increases in TIMI 3 flow when combined with half the usual dose of alteplase. This improvement in reperfusion with alteplase occurred without an increase in the risk of major bleeding. Substantial reductions in heparin dosing may reduce the risk of bleeding even further. Modest improvements in TIMI 3 flow were seen when abciximab was combined with streptokinase, but there was an increased risk of bleeding.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Fragmentos Fab das Imunoglobulinas/uso terapêutico , Infarto do Miocárdio/terapia , Inibidores da Agregação Plaquetária/uso terapêutico , Terapia Trombolítica , Abciximab , Adolescente , Adulto , Idoso , Anticorpos Monoclonais/efeitos adversos , Terapia Combinada , Angiografia Coronária , Relação Dose-Resposta a Droga , Feminino , Humanos , Fragmentos Fab das Imunoglobulinas/efeitos adversos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico por imagem , Inibidores da Agregação Plaquetária/efeitos adversos
10.
J Am Coll Cardiol ; 21(6): 1419-27, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8473651

RESUMO

OBJECTIVES: This study assessed the ability of signal-averaged electrocardiography, radionuclide ventriculography and Holter electrocardiographic (ECG) monitoring and clinical variables to identify patients at risk of serious arrhythmic events after myocardial infarction in the thrombolytic era. BACKGROUND: Most studies of signal-averaged electrocardiography, radionuclide ventriculography and Holter ECG monitoring in risk stratification after myocardial infarction preceded the introduction of thrombolytic therapy. METHODS: A consecutive series of 301 survivors of myocardial infarction, 205 (68%) of whom received thrombolytic agents, underwent signal-averaged electrocardiography (1st 48 h, day 6 and discharge), Holter ECG monitoring (days 6 to 7) and radionuclide left ventriculography (days 7 to 14). Median follow-up time was 1.03 years. RESULTS: Thirteen patients (4.3%) had an arrhythmic event (sudden death in 11, sustained ventricular tachyarrhythmia in 2). The 25-Hz high pass filtered signal-averaged ECG at discharge was 64% sensitive (95% confidence intervals [CI] 36% to 92%) and 81% specific (95% CI 76% to 86%). High grade ventricular ectopic activity on the Holter ECG was only 38% sensitive (95% CI 12% to 64%) and 74% specific (95% CI 71% to 77%). Left ventricular ejection fraction < 0.4 was the best test for prediction of arrhythmic events (sensitivity 75% [95% CI 50% to 100%] and specificity 81% [95% CI 76% to 85%]). In multivariate analysis, in rank order, digoxin therapy at discharge, an abnormal 25-Hz signal-averaged ECG before discharge, absence of angina before index infarction and previous infarction were predictive of arrhythmic events. With digoxin therapy excluded, ejection fraction was an independent predictor. Discriminant analysis identified a high risk group (12% of the study patients) with an event rate of 26%. CONCLUSIONS: The signal-averaged ECG and left ventricular ejection fraction are each independently predictive of arrhythmic events after myocardial infarction, but the Holter ECG is not. A combination of clinical and investigative variables, including the signal-averaged ECG, best identifies patients at highest risk.


Assuntos
Arritmias Cardíacas/diagnóstico , Eletrocardiografia , Infarto do Miocárdio/tratamento farmacológico , Idoso , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/fisiopatologia , Eletrocardiografia/métodos , Eletrocardiografia Ambulatorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Infarto do Miocárdio/complicações , Infarto do Miocárdio/fisiopatologia , Prognóstico , Estudos Prospectivos , Angiografia Cintilográfica , Sensibilidade e Especificidade , Estreptoquinase/uso terapêutico , Análise de Sobrevida , Ativador de Plasminogênio Tecidual/uso terapêutico
11.
J Am Coll Cardiol ; 39(3): 377-86, 2002 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-11823073

RESUMO

OBJECTIVES: This study was designed to test the hypothesis that eptifibatide and reduced-dose tissue plasminogen activator (t-PA) will enhance infarct artery patency at 60 min in patients with acute myocardial infarction (AMI). BACKGROUND: Combination fibrin and platelet lysis improves epicardial and myocardial reperfusion in AMI. METHODS: Patients were enrolled in a dose finding (Phase A, n = 344) followed by a dose confirmation (Phase B, n = 305) protocol. All patients received aspirin and weight-adjusted heparin and underwent angiography at 60 and 90 min. In Phase A, eptifibatide in a single or double bolus (30 min apart) of 180, 180/90 or 180/180 microg/kg followed by an infusion of 1.33 or 2.0 microg/kg per min was sequentially added to 25 or 50 mg of t-PA. In Phase B, patients were randomized to: 1) double-bolus eptifibatide 180/90 (30 min apart) and 1.33 microg/kg per min infusion with 50 mg t-PA (Group I); 2) 180/90 (10 min apart) and 2.0 g/kg per min with 50 mg t-PA (Group II); or 3) full-dose, weight-adjusted t-PA (Group III). RESULTS: In Phase A, the best rate of Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 was achieved using 180/90/1.33 microg/kg per min eptifibatide with 50 mg t-PA: 65% and 78% at 60 and 90 min, respectively. In Phase B, the incidence of TIMI flow grade 3 at 60 min was 42%, 56% and 40%, for Groups I through III, respectively (p = 0.04, Group II vs. Group III). The median corrected TIMI frame count was 38, 33 and 50, respectively (p = 0.02). TIMI major bleeding was reported in 8%, 11% and 6%, respectively; intracranial hemorrhage occurred in 1%, 3% and 2% of patients (p > 0.5 for both). The incidences of death (4%, 5% and 7%), reinfarction or revascularization at 30 days were similar among the three treatment groups. CONCLUSIONS: In comparison with standard t-PA regimen, double-bolus eptifibatide (10 min apart) with a 48-h infusion and half-dose t-PA (Group II) is associated with improved quality and speed of reperfusion. The safety profile of this therapy is similar to that of other combination regimens.


Assuntos
Fibrinolíticos/uso terapêutico , Infarto do Miocárdio/tratamento farmacológico , Peptídeos/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , Ativador de Plasminogênio Tecidual/uso terapêutico , Adulto , Idoso , Vasos Coronários/efeitos dos fármacos , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Eletrocardiografia , Eptifibatida , Europa (Continente)/epidemiologia , Feminino , Humanos , Incidência , Hemorragias Intracranianas/induzido quimicamente , Hemorragias Intracranianas/mortalidade , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/complicações , Infarto do Miocárdio/diagnóstico por imagem , América do Norte/epidemiologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Radiografia , África do Sul/epidemiologia , Análise de Sobrevida , Trombocitopenia/induzido quimicamente , Fatores de Tempo , Resultado do Tratamento , Grau de Desobstrução Vascular/efeitos dos fármacos
12.
Indian Pacing Electrophysiol J ; 5(4): 289-95, 2005 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-16943878

RESUMO

The modern generation of transthoracic defibrillators now employ impedance compensated biphasic waveforms. These new devices are superior to those with monophasic waveforms and practice is currently switching to biphasic defibrillators for the treatment of both ventricular and atrial fibrillation. However, there is no universal guideline for the use of biphasic defibrillators in direct current cardioversion of atrial fibrillation. This article reviews the use of biphasic defibrillation waveforms for transthoracic cardioversion of atrial fibrillation.

13.
Cardiovasc Res ; 28(6): 894-900, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-7522965

RESUMO

OBJECTIVE: The aim was to test the ability of levcromakalim, a potassium channel opener, and sodium nitroprusside, a nitric oxide donor, to reverse the systemic and pulmonary vasoconstrictor actions of NG-nitro-L-arginine methyl ester (L-NAME), and thus to restore cardiac output in anaesthetised pigs. METHODS: In separate groups of pigs administration of a bolus of L-NAME (10 mg.kg-1) was followed either by no further agent (control group; n = 8) or by increasing bolus doses of levcromakalim (10, 20, and 40 micrograms.kg-1; n = 8) or by increasing infused doses of sodium nitroprusside (1, 2, and 4 micrograms.kg-1.min-1 for 15 min at each dose). The same doses of levcromakalim and sodium nitroprusside were also given to pigs (n = 6 in each group) which had been pretreated with saline rather than L-NAME. The changes in systemic and pulmonary haemodynamic indices and cardiac output as a result of each intervention were measured at each stage and compared between and within drug groups. RESULTS: In each group, the bolus of L-NAME caused increases in systemic vascular resistance, mean arterial pressure, pulmonary vascular resistance, and mean pulmonary artery pressure, and a reduction in cardiac output. These effects were significantly different from pretreatment values at 15 min, and were maintained for at least 60 min when no further agent was given. The subsequent administration of levcromakalim caused significant reductions in systemic vascular resistance and mean arterial pressure, the effects being greater than in animals that had been pretreated with saline rather than L-NAME. Pulmonary vascular resistance and mean pulmonary artery pressure were also reduced, but to a lesser degree. Cardiac output was partially but significantly restored. The subsequent administration of sodium nitroprusside caused significant reductions in systemic vascular resistance, mean arterial pressure, pulmonary vascular resistance, and mean pulmonary artery pressure. These effects were significantly greater than those in animals that had been pretreated with saline rather than L-NAME. Cardiac output was weakly, though significantly restored. CONCLUSIONS: Increased systemic vascular resistance following a bolus of L-NAME (10 mg.kg-1) is reversed by subsequent administration of levcromakalim (10-40 micrograms.kg-1) or sodium nitroprusside (1-4 micrograms.kg-1.min-1) associated with partial restoration of cardiac output. The degree to which cardiac output is restored by these two agents is limited by a concomitant reduction in preload.


Assuntos
Aminoácido Oxirredutases/antagonistas & inibidores , Arginina/análogos & derivados , Óxido Nítrico/antagonistas & inibidores , Vasoconstrição/efeitos dos fármacos , Vasodilatadores/farmacologia , Animais , Arginina/farmacologia , Benzopiranos/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Débito Cardíaco/efeitos dos fármacos , Cromakalim , Feminino , Masculino , NG-Nitroarginina Metil Éster , Óxido Nítrico Sintase , Nitroprussiato/farmacologia , Artéria Pulmonar , Pirróis/farmacologia , Suínos , Resistência Vascular/efeitos dos fármacos
14.
Am Heart J ; 145(6): 986-92, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12796753

RESUMO

BACKGROUND: The independent predictive value of d-dimer and inflammatory markers for the risk of recurrent adverse events in patients with acute chest pain but normal levels of cardiac troponin I (cTnI) remains unclear. METHODS: We studied 391 patients admitted to the hospital in 1 year with acute ischemic-type chest pain. Creatine kinase-myocardial band isoenzyme (CK-MB) mass and cTnI levels were measured in initial and 12-hour samples. Soluble intercellular adhesion molecule (sICAM)-1, vascular cell adhesion molecule (sVCAM)-1, sP-selectin, sE-selectin, high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL6), fibrinogen, and d-dimer levels were measured in initial samples. A 1-year incidence of death, myocardial infarction (MI), revascularization, or readmission with chest pain was determined (with death/MI as the primary end point). RESULTS: Patients with normal levels of CK-MB(mass) and cTnI (195/391[50%]) were at a lower risk than patients with elevated levels of CK-MB(mass) or cTnI, but still had an important incidence of events (77/195[39%]). Marker elevation was defined as >75th percentile (upper quartile). Elevated d-dimer levels (>580 ng/mL) was predictive of death/MI (odds ratio, 5.4; 95% CI, 1.5-20.2; P =.005). Elevated sP-selectin levels (>152 ng/mL; odds ratio, 3.2; 95% CI, 0.9-11.6; P =.06) trended to increased death/MI rates, with weaker trends for elevated levels of hsCRP (>7.1 mg/L), IL6 (>10.7 pg/mL), and ST depression. Other markers, other electrocardiogram changes, or classic risk factors were not predictive of death/MI. With a multivariate analysis, d-dimer and sP-selectin were found to be of independent significance for death/MI after adjustment for inflammatory, hemostatic, and electrocardiogram markers and d-dimer after adjustment for classic risk factors. CONCLUSION: Normal cTnI levels after acute chest pain does not confer absence of future risk. Concurrent assessment of d-dimer and inflammatory markers may improve risk stratification.


Assuntos
Biomarcadores/sangue , Isquemia Miocárdica/sangue , Análise de Variância , Proteína C-Reativa/análise , Creatina Quinase/sangue , Creatina Quinase Forma MB , Selectina E/sangue , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Humanos , Isoenzimas/sangue , Infarto do Miocárdio/sangue , Infarto do Miocárdio/mortalidade , Razão de Chances , Selectina-P/sangue , Recidiva , Medição de Risco , Troponina I/sangue , Troponina T , Molécula 1 de Adesão de Célula Vascular/sangue
15.
Am Heart J ; 146(3): 484-8, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12947367

RESUMO

AIMS: A fibrinolytic agent more effective than streptokinase available for bolus injection with reasonable cost-effectiveness is a desirable goal. Pilot studies with bolus pegulated staphylokinase (PEG-Sak) have revealed excellent Thrombolysis In Myocardial Infarction (TIMI) 3 60-minute flow. METHODS AND RESULTS: We evaluated patients with acute ST-elevation myocardial infarction within 6 hours of chest pain onset to determine a dose of PEG-Sak that had at least equal efficacy to recombinant tissue plasminogen activator (rt-PA) while maintaining an acceptable safety profile. After the initial study of 38 patients, of whom 27 received PEG-Sak, enrollment was temporarily halted because 3 patients receiving PEG-Sak had intracranial hemorrhage: 1 at a dose of 0.15 mg/kg and 2 at a dose of 0.05 mg/kg. Overall, 378 patients were studied across a PEG-Sak dose range from 0.01 mg/kg to 0.015 mg/kg, and 122 patients received accelerated rt-PA. At the lowest dose of PEG-Sak studied, 0.01 mg/kg, there was suggestive evidence of attenuation of efficacy; the point estimate for TIMI 3 flow was 24% (95% CI 9%-38%). At doses of 0.01875 to 0.0375 mg/kg (n = 314), TIMI 3 flow rates were 33% (95% CI 27%-38%), whereas the TIMI 3 flow was 41% (95% CI 20%-61%) at the highest PEG-Sak dose studied, 0.05 mg/kg (n = 23), which was similar to that found with rt-PA, 41% (95% CI 32%-50%). CONCLUSION: The efficacy of PEG-Sak, coupled with its ease of administration, provide further impetus for further study in acute myocardial infarction.


Assuntos
Fibrinolíticos/administração & dosagem , Metaloendopeptidases/administração & dosagem , Infarto do Miocárdio/tratamento farmacológico , Estreptoquinase/administração & dosagem , Terapia Trombolítica , Ativador de Plasminogênio Tecidual/administração & dosagem , Adulto , Idoso , Análise de Variância , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estatísticas não Paramétricas
16.
Am J Cardiol ; 86(7): 736-41, 2000 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-11018192

RESUMO

Assessment of reperfusion by the 12-lead electrocardiogram (ECG) or biochemical markers is limited by suboptimal sensitivity and/or specificity. Body surface mapping (BSM) improves the spatial sampling of the 12-lead ECG. Serial 12-lead ECGs and 64-lead anterior BSMs were recorded from 67 patients with acute myocardial infarction undergoing coronary angiography 90 minutes after fibrinolytic therapy. ECG-1 and BSM-1 were recorded before/shortly after therapy (median 18 minutes). ECG-2 and BSM-2 were recorded after the 90-minute angiogram (median 30 minutes). The maximum ST elevation on ECG-1 was noted and > or = 30% ST resolution on ECG-2 was taken to represent partial/complete reperfusion. Patients were randomly divided into a training set and validation set. Isointegral and isopotential ST-T variables from BSMs of training-set patients were compared with Thrombolysis In Myocardial Infarction (TIMI) trial flow using discriminant analysis to identify which variables best classified reperfusion. Reperfusion (TIMI 2/3 flow) occurred in 32 of 34 training-set patients and in 29 of 33 validation-set patients. In the training set, > or = 30% ST resolution correctly classified reperfusion with 72% sensitivity (23 of 32) and 50% specificity (1 of 2). In the validation set, > or = 30% ST resolution classified reperfusion with 59% sensitivity (17 of 29) and 50% specificity (2 of 4). In comparison, a model containing 24 BSM variables correctly classified all training-set patients, and when prospectively tested in the validation-set, correctly classified 28 of 29 patients who achieved reperfusion (97% sensitivity) and all 4 patients who failed to reperfuse (p = 0.035). In conclusion, BSM is more useful than the 12-lead ECG for noninvasive assessment of reperfusion after fibrinolytic therapy for acute myocardial infarction.


Assuntos
Mapeamento Potencial de Superfície Corporal/métodos , Circulação Coronária/fisiologia , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/fisiopatologia , Análise de Variância , Biomarcadores/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade
17.
Am J Cardiol ; 85(8): 934-8, 2000 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-10760329

RESUMO

Right ventricular (RV) or posterior infarction associated with inferior wall left ventricular acute myocardial infarction (AMI) has important therapeutic and prognostic implications. However, RV and posterior chest leads in addition to the 12-lead electrocardiogram are required for accurate detection. Body surface mapping (BSM) has greater spatial sampling and may further improve inferior wall AMI classification. Consecutive patients with chest pain lasting <12 hours were assessed to identify those with AMI and > or =0.1 mV ST elevation in > or =2 contiguous inferior leads of the 12-lead electrocardiogram (bundle branch block or left ventricular hypertrophy excluded). A 12-lead electrocardiogram, RV leads (V(2)R, V(4)R), posterior chest leads (V(7), V(9)), and a BSM were recorded. From each BSM, the 12 electrodes overlying the RV region (regional RV map) and 10 electrodes overlying the posterior wall (regional posterior map) were assessed for ST elevation. Infarct size was estimated by serial cardiac enzymes. AMI occurred in 173 of 479 patients. Of the 62 patients with inferior wall AMI, ST elevation > or =0.1 mV occurred in 26 patients (42 in V(2)R or V(4)R compared with 36 patients (58%) in > or =1 electrode on the regional RV map (p = 0.0019). ST elevation > or =0.1 mV occurred in 1 patient (2%) in V(7) or V(9) compared with 17 patients (27%) in > or =1 electrode on the regional posterior map (p = 0.00003). ST elevation > or =0.05 mV occurred in 6 patients (10%) in V(7) or V(9) compared with 22 patients (36%) in > or =1 electrode on the regional posterior map (p = 0.00003). Patients with ST elevation on regional RV and/or posterior maps had a trend toward larger infarct size (mean peak creatine kinase 1,789+/-226 vs. 1,546+/-392 mmol/L; p = NS). Thus, BSM, when compared with RV or posterior chest leads, provides improved classification of patients with inferior wall AMI and RV or posterior wall involvement.


Assuntos
Mapeamento Potencial de Superfície Corporal , Eletrocardiografia , Infarto do Miocárdio/diagnóstico , Ensaios Enzimáticos Clínicos , Eletrodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/terapia , Reperfusão Miocárdica , Fatores de Tempo
18.
Am J Cardiol ; 64(12): 741-4, 1989 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-2801525

RESUMO

Electrode pad size is an important determinant of transthoracic current flow during external countershock. Self-adhesive, dual function electrocardiogram/defibrillator pads were used to assess the effect of electrode pad size on defibrillation success with low energy (200 J) shocks. The study analyzed 123 cardiac arrests due to primary ventricular fibrillation (VF) in 105 patients (74 men, 31 women) ages 40 to 84 years (mean 64). Transthoracic impedance was measured before defibrillation using a low amplitude 30-kHz current passed through the chest by way of the electrocardiogram/defibrillator pads applied anteroanteriorly. Pad diameters were small (8/8 cm) in 26 cardiac arrests, intermediate (8/12 cm) in 63 arrests and large (12/12 cm) in 34 cardiac arrests. Transthoracic impedance decreased with increasing pad size (112 +/- 17 vs 92 +/- 22 vs 72 +/- 14 omega, respectively, p = 0.0001). Only the first episode of primary VF during a cardiac arrest was analyzed. A single shock of 200 J (delivered energy) was successful in 8 of 26 (31%) arrests using small pads, in 40 of 63 (63%) with intermediate pads and in 28 of 34 (82%) with large pads (p = 0.0003). A second 200-J shock increased the cumulative defibrillation rates to 12 of 26 (46%), 50 of 63 (79%) and 33 of 34 (97%), respectively (p less than 0.0001). In primary VF, larger self-adhesive electrocardiogram/defibrillator pads are associated with a lower transthoracic impedance and improved defibrillation success rates with low energy shocks.


Assuntos
Cardioversão Elétrica/instrumentação , Parada Cardíaca/terapia , Fibrilação Ventricular/terapia , Adesivos , Adulto , Idoso , Idoso de 80 Anos ou mais , Cardiografia de Impedância , Eletrocardiografia/instrumentação , Eletrodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
19.
Am J Cardiol ; 68(9): 909-12, 1991 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-1927950

RESUMO

A cellular transtelephonic defibrillator facilitates early defibrillation in remote areas and involves electrocardiographic diagnosis and defibrillation control by a physician remote from but in voice contact with the patient-unit operator. The patient unit contains a microprocessor, microphone, defibrillator, electrocardiogram/defibrillator electrode pads and cellular telephone. Activation of the patient-unit initiates automatic dialing and contact with the remotely sited base station within 35 to 50 seconds. The physician at the base station identifies the rhythm and controls defibrillator charging and discharge. The minimal interaction required between the system and the local operator makes it suitable for use by minimally trained first responders. The cellular transtelephonic defibrillator has been tested in 211 calls responded to by a physician-manned mobile coronary care unit over distances up to 15 miles in an urban area. Satisfactory electrocardiographic transmission and voice communication were established in 172 of 211 calls (81.5%). In 39 (18.5%), connection with the base station either could not be established or maintained mainly because of geographic location or battery failure. One hundred direct current shocks of 50 to 360 J were effectively administered to 22 patients with 48 episodes of ventricular fibrillation or ventricular tachycardia with successful correction of 46 of 48 episodes using 1 to 4 shocks per episode. Widespread distribution of such devices could improve survival in patients with cardiac arrest outside the hospital.


Assuntos
Assistência Ambulatorial/métodos , Cardioversão Elétrica/instrumentação , Sistemas de Comunicação entre Serviços de Emergência , Parada Cardíaca/terapia , Telefone/instrumentação , Ambulâncias , Falha de Equipamento , Humanos , População Urbana
20.
Am J Cardiol ; 47(6): 1301-8, 1981 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-6263071

RESUMO

Eleven patients with acquired prolongation of the Q-Tc interval and recurrent ventricular tachyarrhythmias were studied. Five patients required 5 to 44 direct current shocks to correct prolonged ventricular tachyarrhythmias, and five were given at least two antiarrhythmic agents in an attempt to control the arrhythmias. In 4 of the 11 patients, when thioridazine, diuretic drugs and antiarrhythmic agents were withdrawn and hypokalemia or hypocalcemia corrected, ventricular tachyarrhythmias did not recur. The Q-Tc interval normalized in 2 to 3 days. Ventricular tachyarrhythmias were recurrent in the remaining seven patients, despite withdrawal of the drugs that caused the Q-Tc prolongation, attempted correction of hypokalemia when present and the administration of antiarrhythmic agents to four of the seven. All antiarrhythmic agents were then withdrawn in this group. Immediately on the establishment of overdrive ventricular or atrioventricular sequential pacing in these patients, ventricular tachyarrhythmias were abolished. No breakthrough ventricular tachyarrhythmias occurred during temporary pacing. Temporary pacing was required for an average of 10 days and the Q-Tc interval normalized an average of 5 days from the onset of pacing. Three patients required a permanent pacemaker, one because of chronic complete heart block, one because of the sick sinus syndrome, and one because of frequent ventricular ectopic complexes complicating ischemic heart disease. All 11 patients survived their period of hospitalization.


Assuntos
Arritmias Cardíacas/terapia , Eletrocardiografia , Adulto , Idoso , Antiarrítmicos/uso terapêutico , Arritmias Cardíacas/tratamento farmacológico , Gluconato de Cálcio/uso terapêutico , Estimulação Cardíaca Artificial , Colecalciferol/uso terapêutico , Feminino , Furosemida/uso terapêutico , Bloqueio Cardíaco/terapia , Humanos , Hipopotassemia/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Tioridazina/uso terapêutico
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