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Results 401 - 450 of 692
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Pak Hui-Nam - - 2004
INTRODUCTION: We previously demonstrated that wavefront synchronization by spatiotemporal excitable gap pacing (Sync P) is effective at facilitating spontaneous termination of ventricular fibrillation (VF). Therefore, we hypothesized that a spatiotemporally controlled defibrillation (STCD) strategy using defibrillation shocks preceded by Sync P can improve defibrillation efficacy. METHOD AND RESULTS: We explored ...
Sharifov Oleg F - - 2004
BACKGROUND: Intramural virtual electrodes (IVEs) are believed to play an important role in defibrillation, but their existence in intact myocardium remains unproven. Here, IVEs were detected by use of optical recordings of shock-induced transmembrane potential (V(m)) changes (DeltaV(m)) measured from the intact epicardial heart surface. METHODS AND RESULTS: To detect ...
Mutlu Gökhan M - - 2004
Vasopressin is a potent vasopressor for improving organ perfusion during septic shock. The rationale for the use of vasopressin is its relative deficiency of plasma levels and hypersensitivity to its vasopressor effects during septic shock. Growing evidence suggests that low-dose (<0.04 U/min) vasopressin is safe and effective for the treatment ...
Guo Wei - - 2004
A new method for the determination of diazepam was proposed based on its polarographic catalytic wave in the presence of persulfate. In 0.20 M NaAc-HAc (pH 4.7)-1.0 x 10(-2) M K(2)S(2)O(8) supporting electrolyte, the reduction wave of diazepam with peak potential -0.89 V (versus SCE) was catalyzed, producing a parallel ...
Berntson Gary G - - 2004
The onset of ventricular depolarization defines the start of the preejection period (PEP), which is commonly used as an index of myocardial contractility and sympathetic control of the heart. Although the fiducial point for this onset has traditionally been the onset of the Q wave of the electrocardiogram, other measurement ...
Burger Joanna - - 2004
In this paper, we report the use of young herring gulls, Larus argentatus, to examine the effect of lead and exercise on endurance, performance, and learning on a treadmill. Eighty 1-day-old herring gull chicks were randomly assigned to either a control group or a lead treatment group that received a ...
Lee Myeong Soo - - 2004
Meridian theory is an important part of traditional Chinese medicine (TCM). Although acupuncture has been accepted in many countries, the nature of the meridian theory and the principles of acupuncture are still unclear in the modern scientific view. The purpose of this study was to determine the differences in wave ...
Jiang Shiqin - - 2004
A computational study of a magneto-electrocardiogram (magneto-ECG) and a correlative locus of the total current dipole vector map are presented. Unlike the ordinary electrocardiogram (ECG), the magneto-ECG is the solution to the inverse problem of electrocardiograph), which is calculated with the magnetic field signals recorded at 36 locations of a ...
Brisinda D - - 2004
The morphology and range of duration of the action potential (AP) in normal Wistar rat's (WR) myocyte markedly differ from those of guinea pigs (GP), whose plateau (phase 2) duration is longer. Thus a clear-cut T wave can be easy defined in GP but not in WR. Aim of this ...
Basar M Murad - - 2004
OBJECTIVE: To investigate the effects of extracorporeal shock-wave lithotripsy (ESWL) applied to the pelvic region on testicular histology and spermatogenesis. MATERIAL AND METHODS: ESWL (2000 shock waves over a 20-min period at 18 kV) was applied to 12 adult New Zealand male rabbits. The rabbits were divided into three equal ...
Menegazzi James J - - 2003
OBJECTIVES: we compared time-dependent rescue shock success when delivered immediately, to defibrillation preceded by 3 min of CPR, with and without high dose epinephrine (HDE) in a swine model of prolonged ventricular fibrillation (VF). Our hypotheses were that pretreatment with CPR and HDE would produce higher rates of successful first-shock ...
Saltykova Marina - - 2003
BACKGROUND: It is known that electroconduction of intrathoracic organs and tissues significantly influences the ECG voltage. It changes during therapy or exercise test due to redistribution and/or volume variations of blood and body fluids and their electroconductivity variations. This fact must be taken into consideration during interpretation of corresponding ECG. ...
Li Li - - 2003
INTRODUCTION: Lidocaine is known to increase the defibrillation threshold (DFT) of monophasic shocks (MS) and have no effect on DFT of biphasic shocks (BS). The aim of this study was to enhance our understanding of the mechanisms of vulnerability and defibrillation through the investigation of this difference. METHODS AND RESULTS: ...
Menegazzi James J - - 2003
The ECC Guidelines 2000 considered interesting new evidence about a pre-defibrillation period of prescribed CPR to increase the probability that the postshock rhythm would be perfusing rather than asystole. If victims of out-of-hospital cardiac arrest have not received bystander CPR before the arrival of the defibrillator, a period of preshock ...
Patruno N - - 2003
BACKGROUND: Recent studies have identified a direct link between the ionic mechanisms responsible for the electrocardiographic (ECG) pattern of the Brugada syndrome (BS) and the in vitro experimental temperature, pointing to the possibility that some BS patients may display the ECG phenotype only during a febrile state, being in this ...
Siegel John H - - 2003
BACKGROUND: The effectiveness of partial resuscitation after hypovolemic hemorrhagic shock with deferment of full resuscitation is critical to successful hypotensive resuscitation. METHODS: To quantitatively address this issue, 40 canines were bled under anesthesia to a mean oxygen debt (O(2)D) of 104 +/- 7.6 mL/kg over 60 minutes (mortality, 40%). Animals ...
Dönmez Nurcan - - 2003
This study was carried out to evaluate the effects of chronic fluorosis by means of the electrocardiograms in sheep. Ten sheep with fluorosis living around a volcanic mountain (Tendürek Mount) in East Anatolia in Turkey and 10 healthy sheep were used. Leads I, II, III, aVR, aVL, aVF, V2, V4, ...
Aström M - - 2003
A method for detecting body position changes that uses the surface vectorcardiogram (VCG) is presented. Such changes are often manifested as sudden shifts in the electrical axis of the heart and can erroneously be interpreted as acute ischaemic events. Axis shifts were detected by analysing the rotation angles obtained from ...
Adams Jose A - - 2003
BACKGROUND: We showed previously that whole body periodic acceleration along the spinal axis (pGz) is a novel method of cardiopulmonary resuscitation (CPR). The ultimate assessment of the value of any CPR technique is the neurological outcome after using such a technique. In this study, we determined the neurological outcome in ...
Lazzoli José Kawazoe - - 2003
BACKGROUND: The importance of vagal tone on cardiac function and cardiovascular mortality is well established. Although the presence of an enhanced cardiac vagal tone (CVT) is frequently diagnosed using the 12-lead resting electrocardiogram (ECG) in daily practice, most of the proposed criteria have been determined on an empirical basis. Our ...
Niemann James T - - 2003
STUDY PURPOSE: Successful defibrillation is dependent upon the delivery of adequate electrical current to the myocardium. One of the major determinant of current flow is transthoracic impedance. Prior work has suggested that impedance falls with repeated shocks during sinus rhythm. The purpose of this study was to evaluate changes in ...
Weber Stefan - - 2003
Beat-to-beat variations in the amplitude of the T wave (T wave alternans [TWA]) have been associated with malignant ventricular arrhythmias in patients with structural heart disease. TWA has also been observed sporadically in healthy persons during strenuous exercise. Therefore, it was the aim of this study to investigate the prevalence ...
Severi Stefano - - 2003
BACKGROUND/AIMS: Sudden K removal is thought to be implicated in ECG alterations observed during hemodialysis (HD). The effects of the K removal rate on ECG-derived parameters have been investigated. METHODS: Two different hemodiafiltration (HDF) schedules were used for 10 HD patients: the dialysate K concentration was kept constant in HDFst, ...
Neagoe Victor -Emil - - 2003
The paper focuses on the neuro-fuzzy classifier called Fuzzy-Gaussian Neural Network (FGNN) to recognize the ECG signals for Ischemic Heart Disease (IHD) diagnosis. The proposed ECG processing cascade has two main stages: (a) Feature extraction from the QRST zone of ECG signals using either the Principal Component Analysis (PCA) or ...
Rodríguez Blanca - - 2003
The goal of this modeling study is to investigate the mechanisms responsible for the upper and lower limits of vulnerability (ULV and LLV) to re-entry induced by electric shocks within the three-dimensional volume of the heart. We use a geometrically accurate rabbit ventricular model with realistic fiber architecture that also ...
Walcott Gregory P - - 2002
OBJECTIVE: This study examined (1) the defibrillation efficacy of using a minimally invasive direct cardiac massage (MID-CM) device as one electrode of the defibrillation electrical circuit and (2) the effect on external defibrillation of defibrillating when the MID-CM device is in place and a pneumothorax is present. METHODS: Part 1: ...
Waldron Julian S - - 2002
BACKGROUND: Microalbuminuria, a marker of endothelial cell dysfunction, is associated with atherosclerosis and is a predictor of coronary heart disease. It has been suggested that patients with coronary heart disease have exaggerated exercise-induced urinary microalbumin excretion but this is controversial. We, therefore, measured urine microalbumin excretion in men before and ...
Szili-Torok Tamas - - 2002
BACKGROUND: Biphasic rectilinear shocks are more effective than monophasic shocks for transthoracic atrial defibrillation and for ventricular arrhythmias during electrophysiological testing. We undertook the present study to compare the efficacy of 100 J rectilinear biphasic waveform shocks with 150 J monophasic damped sine waveform shocks for transthoracic defibrillation of true ...
Sawada T - - 2002
AIMS: Dispersion of ventricular depolarization-repolarization in 12-lead electrocardiograms (ECGs) has been reported to provide noninvasive information on arrhythmogenicity. However, there are two methods to calculate the dispersion from ECGs including and excluding limb leads. The aim of this study was to examine whether temporal parameters from limb leads represent activation ...
Altunkeser Bülent B - - 2002
The previous studies relating to the effect of the Valsalva maneuver on P wave do not provide detailed information. In those studies, the parameters related to P wave duration during the release phase of the Valsalva maneuver were evaluated. The authors evaluated P wave amplitude as well as P wave ...
di Bernardo Diego - - 2002
The mechanisms responsible for changes in T wave symmetry and amplitude with changes in heart rate and action potential duration were investigated. A computer model of normal left ventricular repolarization was used to simulate the T waves on the surface 12-lead ECG. The effect of heart rate changes was studied ...
Bloomfield Daniel M - - 2002
Measurement of microvolt-level T wave alternans (TWA) during routine exercise stress testing now is possible as a result of sophisticated noise reduction techniques and analytic methods that have become commercially available. Even though this technology is new, the available data suggest that microvolt TWA is a potent predictor of arrhythmia ...
Clementy J - - 2002
For physicians who are not familiar with the electrical basis of cardiac stimulation, high impedance leads previously (10 years ago) considered as bad electrodes (high voltage) are now considered as the 'epitome' of lead technology (low energy drain): clearly impedance is not a good parameter for characterizing the qualities of ...
Huang Jian - - 2002
This study tested the hypothesis that the DFT could be lowered by delivering a weak auxiliary shock in conjunction with a stronger primary shock with the auxiliary shock electrode near the cardiac region where the primary shock electric field is weakest. This hypothesis was tested by determining the DFTs with ...
Cairns C B - - 2001
In 1862, Samuel Gross described shock as the "rude unhinging" of the machinery of life. As noted above, adequate oxygen delivery and metabolism are essential to the maintenance of cellular energy stores. Failure of adequate tissue oxygen delivery and utilization during shock can lead to organ dysfunction and death. Hemorrhagic ...
Sado D M - - 2001
Transthoracic impedance (TTI) is an important determinant of success in defibrillation. Low TTI increases transmyocardial current and therefore increases the chance of depolarising a critical mass of myocardium. A major component of TTI occurs at the paddle-skin interface and is minimised by pressure applied to the defibrillation paddles. The International ...
Rao S S - - 2001
The pathophysiology of slow transit constipation is poorly understood. Both decreased and increased distal colonic motility have been reported. In healthy humans, a 3 cycles per minute (cpm), periodic rectal motor activity (PRMA) has been described. Our aim was to investigate the characteristics of PRMA and to assess its role ...
Kuroda N - - 2001
The relationship between the QT indices and microvolt-level T wave alternans (TWA) is unknown in cardiomyopathy, so the present study examined 86 patients with cardiomyopathy who experienced TWA during exercise testing (EXT). The QT interval (QT), duration from the Q wave to the peak of the T wave (QTp), duration ...
Kang Derwent J J - - 2001
Kang Derwent and Linsenmeier (2000) reported that the a- and b-waves of the cat electroretinogram (ERG) are resistant to hypoxemia, at least for PaO2 above 40 mm Hg. The a-wave may be resistant because the photoreceptor can increase glycolysis during hypoxemia. This hypothesis was tested by making the animal hypoglycemic, ...
Garcia S L - - 2001
The survival and molting incidence of fifth-instar nymphs of Panstrongylus megistus (Burmeister, 1835), a vector of Chagas' disease, were investigated following sequential heat shocks in which a mild shock (35 or 40 degrees C, 1 h) preceded a more drastic one (40 degrees C, 12 h). The shocks were separated ...
Amann A - - 2001
Mean fibrillation frequency may predict defibrillation success during cardiopulmonary resuscitation (CPR). N(alpha)-histogram analysis should be investigated as an alternative. After 4 min of cardiac arrest, and 3 versus 8 min of CPR, 25 pigs received either vasopressin or epinephrine (0.4, 0.4, and 0.8 U/kg vasopressin versus 45, 45, and 200 ...
Weiss C - - 2001
Ablation catheters with multiple long coiled electrodes have been recently developed to induce continuous linear lesions for the treatment of atrial fibrillation. The efficacy and safety of ablation catheters with multiple long coiled electrodes has not been evaluated. The aim of the present in vivo study was to investigate the ...
Madbouly K - - 2001
PURPOSE: We determined whether there is a significant relationship between the spatial anatomy of the lower pole on preoperative excretory urography and stone fragment clearance after shock wave lithotripsy. MATERIALS AND METHODS: The anatomical factors affecting lower pole stone clearance after shock wave lithotripsy were evaluated retrospectively in 108 patients. ...
Nonokawa M - - 2001
Preexcitation in Wolff-Parkinson-White syndrome (WPW) has been reported to induce long-lasting changes in ventricular recovery properties. However, there has not been a report concerning changes in the activation-recovery interval (ARI) in 12-lead ECGs before and after catheter ablation (CA) in patients with WPW syndrome. The present study compared changes in ...
Ramanathan C - - 2001
INTRODUCTION: Body surface potential maps (BSPMs) and conventional ECG reflect electrical sources generated by cardiac excitation and repolarization and noninvasively provide important diagnostic information about the electrical state of the heart. Because the heart is located within the torso volume conductor, body surface potentials also reflect the effects of torso ...
Wischer S - - 2001
OBJECTIVE: To investigate by means of transcranial magnetic stimulation (TMS) the effect of a single oral dose of the GABA derivate piracetam on intracortical facilitatory I-wave interaction. METHODS: The study was performed in 8 healthy volunteers. Before, 1, 3, 6, and 24 h after intake of 4000 mg piracetam, MEPs ...
Ghuran A - - 2000
Automatic recognition of repolarization abnormalities from the standard electrocardiogram (ECG) is of considerable clinical importance. This study examined the autonomic variations in automatically measured repolarization parameters, including maximum QT interval (QTmax), global QT dispersion (QTd), T area dispersion (T area D) and principal component analysis ratio 2 (PCA-2). Twelve-lead ECGs ...
Omrani A - - 2000
The effects of pentylenetetrazol (PTZ) following induction of long-term potentiation (LTP) on population spikes in CA1 of hippocampal slices were investigated. Population spikes were evoked by activation of Schaffer collaterals with a range of stimulation intensities. LTP was induced using &theta;-pattern primed burst tetanic stimulation. Changes in the population spike ...
Chattipakorn N - - 2000
INTRODUCTION: A recent study of shocks near defibrillation threshold (DFT) strength demonstrated that at least three rapid cycles always occur after failed shocks but not after successful shocks, suggesting that the number and rapidity of postshock cycles are important in determining defibrillation success. To test this hypothesis, rapid pacing was ...
Childs E W - - 2000
The activation and adherence of leukocytes to the venular endothelium are critical steps in the pathogenesis of generalized microvascular injury following hemorrhagic shock. Previous studies have shown that the integrins CD11/CD18 play a significant role in this interaction. The purpose of this study is to examine the efficacy of anti-LFA-1beta, ...
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