Acute cardiac events involving coronary symptoms, elevated enzyme levels, and electrocardiographic changes without the development of Q waves often result in higher rates of reinfarction and unstable angina than do more severe myocardial infarctions. The incidence of these non-Q wave events is on the rise, possibly because of earlier detection ...

Spatial heterogeneity in the refractoriness of the ventricular myocardium due to a regionally prolonged refractory period has often been observed in patients with cardiovascular disease as the substrate for functional reentrant tachyarrhythmias. The present study sought to determine how functional reentrant activity could occur due to the spatial heterogeneity, using ...

In this experiment, we measured ECG signals of lead I, respectively, during normal and arrhythmia after 20 rabbits were anaesthetized. These signals were recorded, then the information was put into a computer and it analyzed Autocorrelation (AC) Function, and Power Spectrum. The results make us know: (1) periodicity corresponding relationship ...

BACKGROUND AND METHODS. Exercise-induced T wave normalization occurring at a low (less-than-or-equal50 watt) workload in infarct-related electrocardiographic leads was studied in 30 consecutive patients with a recent transmural anterior acute myocardial infarction. Patients underwent both ergometric stress testing (within 30 days after the infarction) and low dose dobutamine echocardiography. The ...

INTRODUCTION: QRS morphology during narrow QRS supraventricular tachycardia in patients without ventricular preexcitation generally is considered the same as that seen during sinus rhythm. This study presents a new ECG observation that the QRS amplitude increased significantly in leads V2 through V5 during tachycardia. METHODS AND RESULTS: Using the same ...

Although atrial signal-averaged electrocardiogram (SAECG) has been proposed for noninvasive identification of patients with atrial tachyarrhythmias, the substantial variability of the measurement limits the clinical value. The aim of the study was to assess the short- to long-term reproducibility of atrial SAECG and to compare it to that of the ...

Profound physiological changes occur following primary blast exposure but the contribution of cardiac arrhythmias is unknown. Thirteen rats, under intravenous anaesthesia, were exposed to a blast wave directed at the thorax (Group II); 10 other animals underwent abdominal blast (Group III) and nine animals acted as controls (Group I). Animals ...

OBJECTIVES: The aim of this study was to describe the electrocardiographic (ECG) evolutionary changes after an acute myocardial infarction (AMI) and to evaluate their correlation with left ventricular function and remodeling. BACKGROUND: The QRS complex changes after AMI have been correlated with infarct size and left ventricular function. By contrast, ...

This study describes major electrocardiogram (ECG) measurements and diagnoses in a population of African individuals; most reference data have been collected in Caucasian populations and evidence exists for interethnic differences in ECG findings. This study was conducted in the Seychelles islands (Indian Ocean) and included 709 black individuals (343 men ...

Most attempts to identify qualitative and quantitative techniques for assessing myocardial viability and the likelihood of improved function after revascularization in patients with healed myocardial infarcts have focused on treatment strategies and prognosis. This review examines the true value of the electrocardiographic phenomenon of exercise-induced ST segment elevation (EISTE) in ...

Analysis of the 12-lead electrocardiogram (ECG) provides important diagnostic and prognostic information in the long QT syndrome. The clinical diagnosis of long QT syndrome is determined by the presence of a QTc > or = 0.44 sec. A normal QTc does not exclude a family member from being a genetic ...

To compare the diagnostic yield of electrocardiograms (ECGs) recorded by 12 standard leads with that of 12-lead ECGs derived from 3 bipolar EASI leads, we analyzed pertinent ECG data for 290 normal subjects and 497 patients who had had a prior myocardial infarction (MI); the latter group comprised 36 patients ...

This study was conducted to elucidate the significance of spontaneous normalization of negative T waves in infarct-related leads during the chronic phase of anterior wall acute myocardial infarction. Results of this study indicate that patients with spontaneous normalization of negative T waves in infarct-related leads between 1 and 6 months ...

OBJECTIVE: To investigate whether QRS morphology on the surface ECG can be used to predict myocardial viability. DESIGN: ECGs of 58 patients with left ventricular impairment undergoing positron emission tomography (PET) were studied. (13)N-Ammonia (NH(3)) and (18)F-fluorodeoxyglucose (FDG) were the perfusion and the metabolic markers, respectively. The myocardium is scarred ...

This study was designed to detect patients with type I silent myocardial ischemia (SMI) at rest by assessing the symmetry of the electrocardiographic (ECG) T wave using the spatial velocity electrocardiogram (SVECG). In this study, the ECG T waves in patients with SMI were symmetric compared with those in normal ...

The Wolff-Parkinson-White syndrome (WPW), estimated to occur in approximately 0.1% to 3% of the general population, is a form of ventricular preexcitation involving an accessory conduction pathway. The definition of WPW relies on the following electrocardiographic features: (1) a PR interval less than 0.12 seconds (2) with a slurring of ...

This study was designed to elucidate whether left precordial negative T waves are electrocardiographic indicators for the diagnosis of hypertrophic cardiomyopathy (HCM) even in the presence of complete right bundle branch block (CRBBB). In 7 consecutive patients with CRBBB accompanied by negative T waves in at least one of the ...

INTRODUCTION: Rotating vortices have been observed in excitable media of different nature. Vortices may sustain life or kill in different species, by underlining morphogenesis in Dictiostelium discoideum during starvation, or arrhythmias during sudden cardiac death in mammals. Investigation of vortices in the heart has been limited by two-dimensional experimental techniques. ...

Induction of complete bidirectional conduction block via the posterior isthmus of the right atrium is introduced as a standard endpoint for catheter ablation of atrial flutter. The present study sought to investigate the impact of changes in P wave duration and morphology detected by the surface ECG during coronary sinus ...

We have studied the spatial properties of ischemic changes as induced by prolonged angioplasty and how the changes are related to different ECG indexes. Indexes based on measurements at specific points in time (ST level at J + 60 ms point, maximal T wave amplitude and position, QT interval, and ...

This study examined the relationships between the polarity of the U wave on intracoronary electrocardiogram (ECG) and the status of myocardial ischemia during angioplasty. The ECG features of ischemia-related U waves were also evaluated. Among 63 patients with intracoronary ECGs adequate for analysis of U waves, there were 26 patients ...

Right atrial appendage (RAA) blood flow pattern was analyzed in 42 normal subjects-without cardiovascular disease (aged 30 to 48 years, mean 40 +/- 6) who underwent transesophageal echocardiography. RAA flow pattern was demonstrated to be bi-, tri- or quadriphasic and heart rate dependent (p < 0.01) in this study. In ...

The study was undertaken to evaluate the relationship of signal-averaged ECG (SA-ECG) readings in the frequency domain (STM) and epicardial electrograms (EE) recorded before and after acute myocardial infarction (AMI) in pigs and to compare the changes with findings in time-domain analysis (TDA). In 20 pigs the left anterior descending ...

BACKGROUND: In epidemiological studies, the electrocardiogram has often been interpreted by means of a categorical classification. Computerized recording offers the possibility of analysing electrocardiographic measurements as continuous variables. OBJECTIVE: To test the hypothesis that duration of QRS complex and T-wave inversion would be independent predictors of myocardial infarction. METHODS: In ...

The prevalence and clinical significance of ST-segment elevation (STE) in posterior electrocardiographic (ECG) leads during acute myocardial infarction (AMI) is largely unknown. We obtained posterior ECG leads (V7, V8, and V9), as well as standard 12-lead and right precordial leads (V4R-V6R), immediately upon admission in 210 consecutive patients with AMI. ...

It is generally accepted in clinical electrocardiography that a right bundle branch block (RBBB) does not interfere with the electrocardiographic (ECG) diagnosis of myocardial infarction (MI). The basic assumption is that the initial excitation wavefronts are relatively unchanged in RBBB. This study compared serial changes in Q wave duration in ...

OBJECTIVE: To compare the incidence of electrocardiographic abnormalities between older (age > or = 70 years) and younger patients presenting with acute non-Q-wave myocardial infarction. DESIGN: Retrospective review of qualifying electrocardiograms in 918 patients enrolled in the multicenter Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) study. SETTING: Seventeen Department of ...

Ventricular fibrillation (VF) in the human heart is not well understood. The aim of this study was to measure changes in the phase relationship between the body surface ECG and intracardiac electrograms recorded during the first 10 s of human VF. We studied 11 episodes of VF and measured the ...

INTRODUCTION: We studied the role of the cardiac renin-angiotensin II system in the genesis of cardiac memory, in which T wave changes induced by ventricular pacing (VP) accumulate and persist during subsequent sinus rhythm. METHODS AND RESULTS: Anesthetized dogs were instrumented via a thoracotomy and three 20-minute runs of VP ...

We present the case of a patient with a DDD pacemaker and intermittent P wave sensing due to T wave oversensing by the ventricular lead. The T wave sensing caused initiation of an extended atrial refractory period and the P waves, falling within this period, were not sensed. The problem ...

BACKGROUND: Although T-wave alternans has been closely associated with vulnerability to ventricular arrhythmias, the cellular processes underlying T-wave alternans and their role, if any, in the mechanism of reentry remain unclear. METHODS AND RESULTS:-T-wave alternans on the surface ECG was elicited in 8 Langendorff-perfused guinea pig hearts during fixed-rate pacing ...

OBJECTIVES: The purpose of this study is to validate the use of tissue Doppler acceleration imaging (TDAI) for evaluation of the onset of ventricular contraction in humans. BACKGROUND: Tissue Doppler acceleration imaging can display the distribution, direction and value of ventricular acceleration responses to myocardial contraction and electrical excitation. METHODS: ...

In the Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital (VANQWISH) trial, most patients with non-Q-wave myocardial infarction (MI) fared no better with early invasive management (i.e., diagnostic angiography within 2 to 3 days, followed by revascularization if indicated) than with a more conservative approach (i.e., radionuclide ventriculography and thallium stress ...

This study was conducted to provide a comprehensive evaluation of both the amplitudes and durations of the Lead II electrocardiogram (ECG) in nonascitic and ascitic broilers. At 14 d of age, male and female broiler chicks were sham-operated (SHAM, n = 27), or pulmonary hypertension was initiated by occluding one ...

BACKGROUND: Studies of healthy volunteers or patients in sinus rhythm have indicated that treatment with digoxin produces characteristic changes in the electrocardiogram (ECG). No randomized, placebo-controlled studies are available and no study has investigated the effect on ECG in patients with atrial fibrillation. HYPOTHESIS: In a substudy to a trial ...

The purpose of this study was to investigate the applicability of computerized electrocardiogram interpretation in classifying patients with suspected acute myocardial infarction. Computerized acquisition and analysis of the 12-lead electrocardiogram can increase the consistency and reduce the workload of patient classification. The serial electrocardiograms of 311 consecutive patients with suspected ...

Conventional criteria of ST segment elevation in right sided chest leads or loss of initial 'r' wave in leads V3R or V4R have low sensitivity and specificity in diagnosing right ventricular involvement in the presence of left ventricular posterior infarction. Slurring of R wave either in right sided chest leads ...

Electrocardiography is useful as a noninvasive technique for detecting right ventricular hypertrophy in birds developing pulmonary hypertension (PH) and pulmonary hypertension syndrome (PHS, ascites). The objective of this study was to identify every aspect of the Lead II ECG wave form (amplitude or duration) that can be correlated with right ...

This study was performed to compare a derived 12-lead electrocardiogram (ECG) using a simple 5-electrode lead configuration (EASI 12-lead) with the standard ECG for multiple cardiac diagnoses. Accurate diagnosis of arrhythmias and ischemia often require analysis of multiple (ideally, 12) ECG leads; however, continuous 12-lead monitoring is impractical in hospital ...

This study examines the electrocardiographic (ECG) changes following rabbit coronavirus (RbCV) infection. We have shown that infection with RbCV results in the development of myocarditis and congestive heart failure and that some survivors of RbCV infection go on to develop dilated cardiomyopathy in the chronic phase. Serial ECGs were recorded ...

The aim of this study was to assess the diagnostic and prognostic value of the presence and characteristics of ischemic electrocardiographic (ECG) changes during dipyridamole stress echocardiography. The ECG response in 178 patients with echocardiographic evidence of myocardial ischemia during dipyridamole stress testing was analyzed. ECG changes occurred in 105 ...

BACKGROUND: To date, Holter monitoring has been predominantly utilized in the investigation and monitoring of ventricular arrhythmias and myocardial ischemia. Whether currently employed lead configurations are optimal for recording atrial electrocardiograms (ECGs) is unknown. HYPOTHESIS: This study was undertaken to determine which conventional and novel lead configurations are optimal for ...

The electrocardiographic diagnosis of ischemic heart disease is made more difficult in the setting of confounding patterns, including left bundle branch block (LBBB). The electrocardiographic detection of abnormalities arising from acute ischemic cardiac disease in this setting is possible in certain cases, contrary to popular medical opinion. Several strategies are ...

Electrocardiographic (ECG) findings of pulmonary embolism (PE) include S1Q3T3 pattern, right bundle-branch block, right-axis deviation, and T-wave inversion in medial precordial leads. We report other uncommon ECG changes associated with various symptoms during recurrent PE as documented by computed tomography (CT) scans in a single patients. An 83-year-old woman was ...

INTRODUCTION: Some posteroseptal accessory pathways (APs) can be successfully ablated by radiofrequency current only from inside the coronary sinus (CS) or its branches, because of an absolute or relatively epicardial location. The aim of this study was to identify ECG features of manifest posteroseptal APs requiring ablation in the CS ...

The clinical significance of U wave is limited to the occasional obfuscation of the end of T wave and an inadequately explained U wave inversion associated with myocardial ischemia, infarction, and ventricular hypertrophy and dilatation. Lengthening of QT interval often interferes with the recognition of U wave. The characteristics of ...

PROBLEM: To determine whether diagnoses of myocardial infarction assigned by a system that uses Marquette 12SL electrocardiographic (ECG) codes with manual over-reading agree with diagnoses assigned by Minnesota ECG codes. STUDIES UNDERTAKEN: Agreement and recode reliability of Minnesota and Mayo coding systems based on 768 ECGs plus chest pain history ...

BACKGROUND: Although moderate caffeine ingestion has not been shown to be arrhythmogenic, caffeine toxicity can cause severe cardiac arrhythmias, including atrial fibrillation and ventricular tachycardia. Atrial fibrillation and ventricular tachycardia have been associated with prolongation of P-wave and QRS complex durations on signal-averaged electrocardiograms. This study investigated acute effects of ...

The aim of this article was to study beat-to-beat QRS variability in patients with ischemia and old myocardial infarction using the 12-lead resting electrocardiogram (ECG). The variability analysis was based on beats that have been synchronized in time with an iterative alignment technique. The QRS variability was measured in patients ...

We investigated the relationships between echocardiographic indices of left ventricular geometry and function and major electrocardiographic (ECG) abnormalities in 540 elderly (69-74 years old) male participants of a health survey conducted in Uppsala county, Sweden. Comparing men with major ECG abnormalities that were present or absent in various hierarchic mutually ...