Interactions between peripheral conduction system and myocardial wave fronts control the ventricular endocardial activation sequence. To assess those interactions during sinus and paced ventricular beats, we recorded unipolar electrograms from 528 electrodes spaced 0.5 mm apart and placed over most of the perfused rabbit right ventricular free wall endocardium. Left ...

OBJECTIVE: To study the sequence of atrial activation and the interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR). METHODS AND RESULTS: In 66 SR healthy subjects P-wave activation was analyzed by means of vectorcardiography. The timing of atrial contractions was measured as the intervals between the ...

AIMS: To compare the outcome of short- and long-term survival of patients with Q wave vs non-Q wave myocardial infarction. METHODS: A total of 6676 patients with acute myocardial infarction were enrolled on the TRAndolapril Cardiac Evaluation (TRACE) register between 1990 and 1992. Medical history, electrocardiographic diagnosis of Q wave ...

OBJECTIVES: The main goal of this study was to determine whether induction of an angerlike state can result in significant levels of T-wave alternans, a marker of electrical instability, in the normal and ischemic heart. BACKGROUND: Outbursts of anger have been implicated in the occurrence of myocardial infarction and sudden ...

Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disorder of unknown etiology that is characterized pathologically by fibrofatty replacement of the right ventricular myocardium. We investigated the relationship between the electrocardiogram (ECG) appearances and signal-averaged ECG (SAECG) in 7 cases with ARVD, and evaluated the usefulness of SAECG as ...

BACKGROUND: The pulmonary venous flow velocity pattern (PVFVP) in atrial septal defect (ASD) has not been previously studied in detail. Normally, PVFVP is primarily determined by the left heart performance. We hypothesized that the impact of left-sided heart dynamics on PVFVP is diminished in patients with ASD because of the ...

The National Heart, Lung, and Blood Institute Dynamic Registry includes 15 clinical sites in wave 1, and 16 sites in wave 2 as well as a data-coordinating center. The first wave of enrollment began in July 1997 and was completed in February 1998. The second wave began in February 1999 ...

This case report describes clinical features, especially of surface ECG changes, observed for 27 years in a patient with arrhythmogenic right ventricular dysplasia (ARVD). The course of this patient was characterized by progressive deterioration of right ventricular function and progression of delayed potentials (so-called epsilon waves) following QRS complexes. However, ...

Regional hyperkalemia during acute myocardial ischemia is a major factor promoting electrophysiological abnormalities leading to ventricular fibrillation (VF). However, steep action potential duration restitution, recently proposed to be a major determinant of VF, is typically decreased rather than increased by hyperkalemia and acute ischemia. To investigate this apparent contradiction, we ...

BACKGROUND: The action potential duration (APD) restitution hypothesis of wave break during ventricular fibrillation (VF) in the epicardial border zone (EBZ) of hearts with chronic myocardial infarction is unknown. METHODS AND RESULTS: VF was induced by rapid pacing, and the EBZ with the two adjoining sites (right ventricle and lateral ...

Electrocardiograms (ECGs) were recorded from 41 healthy macaws (Ara species) and 31 healthy cockatoos (Cacatua species). All birds were anesthetized via face mask with isoflurane anesthesia. Standard bipolar (I, II, III) and augmented unipolar (aVR, aVL, aVF, V10) leads were recorded with birds in dorsal recumbency using a direct-writing oscillograph. ...

OBJECTIVE: The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of ...

Highly trained athletes show a variety of electrocardiographic (ECG) changes, including a striking increase of R or S wave voltage, either flat or deeply inverted T waves, and deep Q waves, that suggest the presence of structural cardiovascular disease, such as hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy, which represent ...

To examine the waveforms of electrocardiograms, cardiac rhythm, heart rates at rest and during excitement, and the rate of increase of heart rate, electrocardiograms were recorded with standard bipolar limb leads from 79 free-living birds, including 19 species. The heart weights and heart-to-body weight ratios were obtained from an additional ...

Intracoronary electrocardiography (IC-ECG) is a more sensitive method than surface ECG to detect electrical changes during percutaneous transluminal coronary angioplasty (PTCA). It also provides direct monitoring of ST-T segment, QTc intervals, and U-wave genesis during balloon inflation. These changes are reflective of myocardial ischemia. The authors studied the effect of ...

BACKGROUND: Left ventricular hypertrophy (LVH) in coronary heart disease is associated with poor prognosis. Electrocardiography (ECG) criteria for LVH, when using ECG with modified limb electrode positions, has not been validated in patients with angina pectoris. METHODS: Echocardiography and resting ECGs with modified limb electrode positions, i.e. with the limb ...

A technical advance in contrast-enhanced magnetic resonance imaging (MRI) has significantly improved image quality. We investigated whether healed myocardial infarction can be visualised as hyperenhanced regions with this new technique, and whether assessment of the transmural extent of infarction yields new physiological data. 82 MRI examinations were carried out in ...

Appropriate sensing is an essential function of an implantable cardioverter defibrillator (ICD). T-wave oversensing by an ICD can be a serious problem in some patients, causing overestimation of the heart rate, inappropriate tachyarrhythmia detection and therapy delivery. Decreasing the sensitivity or programming longer refractory periods can sometimes overcome T-wave oversensing, ...

This study aimed to clarify whether spontaneous T-wave normalization (TWN) in infarct-related leads reflects improvement in left ventricular (LV) wall motion even in patients with persistent abnormal Q waves after acute myocardial infarction (AMI). Eighty-five patients were classified into the following 3 groups: patients with Q-wave regression (group A, n ...

Computer models, such as those produced by Solomon and Selvester, have helped increase our understanding of the heart's electrical activity. In the present report, we describe a dynamic three-dimensional computerized display of the myocardial excitation sequence that is based on this fundamental research. The display is based on the vectors ...

This article discusses three different perspectives of the electrical activity of the human heart based on three types of electrocardiographic recordings: the Surface ECG, the Subcutaneous ECG, and the Intracardiac Electrogram. Although all three types of recordings are generated by the same electrical activity, namely, the depolarization and repolarization of ...

INTRODUCTION: A negative electroretinogram (ERG) is one in which there is a selective reduction in amplitude of the b-wave, such that it does not exceed that of the a-wave. The purpose of this study was to determine the incidence and clinical causes of negative ERGs at a tertiary referral centre. ...

It is important that critical care nurses are able to identify the location of cardiac muscle ischemia, injury, and infarction on the electrocardiogram. Knowing the site of infarction is essential in anticipating clinical manifestations and, therefore, has implications for the patient's plan of care. This article includes an overview of ...

BACKGROUND: Some patients with acute myocardial infarction presenting without significant ST segment elevation develop a Q-wave infarction. It is unclear whether these patients can be identified from the admission electrocardiogram (ECG) and whether they differ in their in-hospital prognosis from those who retain a non-Q-wave myocardial infarction. METHODS: In 432 ...

OBJECTIVE: Hypothermia is known to adversely affect the electrocardiogram (ECG) in many cases. This study set out to determine the incidence of defined cardiac dysrhythmias, J waves, and conduction abnormalities in urban hypothermia. METHODS: A prospective, multicenter study was carried out to determine the incidence of defined cardiac rhythms in ...

T-wave alternans (TWA) is a harbinger of ventricular vulnerability and an important prognostic indicator for torsade de pointes and likely sudden death in patients with LQTS. We analyzed the occurrence of TWA in 18 patients with LQTS (7 males, 11 females, ages ranging from 6 months to 32 years--median 8.4 ...

Previously, using an animal model of T-wave alternans in structurally normal myocardium, we demonstrated that repolarization can alternate with opposite phase between neighboring myocytes (ie, discordant alternans), causing spatial dispersions of repolarization that form the substrate for functional block and reentrant ventricular fibrillation (VF). However, the mechanisms responsible for cellular ...

AIMS: To compare the role of early invasive vs conservative management strategies in treating patients with non-Q wave myocardial infarction with or without a prior myocardial infarction. BACKGROUND: In patients recovering from non-Q wave myocardial infarction, the prognosis among patients with a first non-Q wave myocardial infarction is significantly better ...

It is important to assess the risk of developing paroxysmal atrial fibrillation (PAF) in hypertensive patients since hypertension is a common disorder predisposing to PAF. We sought to determine if patients with hypertension at risk of PAF can be identified while in sinus rhythm by measurements of P wave dispersion. ...

In Wolff-Parkinson-White syndrome, the sequence of ventricular activation is altered and depending on the anatomic site of the accessory conduction pathway may result in pseudo ventricular hypertrophy and pseudo myocardial infarction patterns on electrocardiogram. The right-sided accessory pathway may direct the depolarization vector towards left amplifying R-wave amplitude in left-sided ...

Right precordial Q waves can be present in patients with aortic stenosis as well as in those with anterior myocardial infarction. In order to evaluate the relationship of right precordial Q waves to left ventricular function and prognosis in patients with aortic stenosis, we studied 49 such patients with no ...

The standard 12-lead electrocardiogram (ECG) gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: (1) ST-segment measurements, ...

The main aim of this study is to re-evaluate the r wave in V1 (rV1) and the initial forces in V6 with normal QRS duration. A total of 741 high-speed simultaneous electrocardiograms of V1 and V6 with either aVF or aVL as reference lead were recorded in patients with cardiac ...

The study was undertaken to determine whether a computer program that uses "short measurement matrix" data from the Marquette Matrix-12 system can replicate Minnesota electrocardiogram (ECG) coding laboratory interpretations. An agreement was found between coding of median complex ECGs at the Minnesota ECG coding laboratory and coding based on Marquette ...

To diagnose posterior and anterior biventricular infarctions it is necessary to record from right and left thoracic and high abdominal unipolar leads. These supplementary leads are dependable, can be repeated as many times as needed and show the evolution from signs of myocardial injury to those of dead tissue (Q ...

BACKGROUND: Postpneumonectomy electrocardiographic (ECG) changes have not been well-defined. METHODS: We reviewed the clinical data and the preoperative and postpneumonectomy ECGs of 15 patients who had pneumonectomy. RESULTS: All postpneumonectomy ECGs showed a higher heart rate and two (13%) showed diffuse ST elevation. Four patients (27%) had transient atrial arrhythmias. ...

BACKGROUND: The aim of this work was to study changes in end-diastolic volume 6 months after Q-wave and non-Q-wave anterior ST-elevation myocardial infarction by echocardiography. Ventricular dilation after anterior Q-wave myocardial infarction is well-recognized. However, there is a dearth of information about the natural history of ventricular volumes after non-Q-wave ...

BACKGROUND: The stratification of post-myocardial infarction (MI) patients at risk of sudden cardiac death remains important. The aim of the present study was to assess the prognostic value of novel T-wave morphology descriptors derived from resting 12-lead ECGs. METHODS AND RESULTS: In 280 consecutive post-MI patients, a 12-lead ECG was ...

AIMS: Worldwide there is a large variation in outcome (death, myocardial infarction and recurrent myocardial infarction) in patients with unstable angina or non-Q wave myocardial infarction. These variations may be explained by differences in characteristics of the presenting patients. Here we describe differences in patient presentation, treatment protocols and outcome ...

The prevalence of late potentials after myocardial infarction depends on the site of the infarction. This may be caused by the different activation onsets of the anterior and inferior myocardial segments. Therefore, in anterior infarcts the high frequency signals may be concealed within the QRS whereas in the inferior infarcts ...

BACKGROUND: Recent studies have reported that negative T waves in the setting of acute coronary events are associated with Thrombolysis In Myocardial Infarction flow grade 3 in the infarct-related artery and with improved parameters of ventricular function rather than with ischemia. METHODS: Patients enrolled in the Global Utilization of Streptokinase ...

Measurement of microvolt level T-wave alternans in the surface electrocardiogram is a novel way to assess the risk of ventricular arrhythmias. Seven tests of arrhythmic risk, including T-wave alternans, were undertaken in 107 consecutive patients with congestive heart failure and no history of sustained ventricular arrhythmias; the patients were followed ...

The standard 12-lead ECG gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST-elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: 1) ST-segment measurements; 2) T-wave ...

The effects of pentazocine on electrocardiogram (ECG) heart and respiratory rates were studied in young sheep and goats as a prelude to its clinical use as an opioid analgesic in the two species. The ECG was monitored by standard bipolar leads that provided discernible electrocardiographic features only in Lead I. ...

In spite of smaller infarct size and better preserved left ventricular function the long-term prognosis after a non-Q-wave infarction is not better than after a Q-wave infarction. In fact, the risk of sudden cardiac death is higher in patients with a non-Q-wave infarction than in patients with a Q-wave infarction. ...

In a pilot study, electrocardiographic (ECG) recordings of patients with left and right coronary stenosis taken before and after angioplasty were analyzed using the continuous wavelet transform. Time-frequency distributions were obtained for different leads in order to examine the dynamics of the QRS-spectrum and establish features specific of ischemia in ...

OBJECTIVES: The relationships that exist between endocardial and surface electrocardiogram (ECG) activity in patients with AFl have not been satisfactorily delineated. The aim of the study was to determine the relationships that exist between the atrial endocardial activity and the surface ECG in patients with atrial flutter (AFl). METHODS: In ...

A 58 year old woman presented with symptoms and electrocardiographic features consistent with acute infero-posterior myocardial infarction. The attempt at reperfusion with aspirin and thrombolytic treatment was deemed unsuccessful in view of Q wave development on ECG, a 48 hour period of hypotension and oliguria, and extensive wall motion abnormality ...

Abnormal Q waves after a myocardial infarction are not always an indicator of myocardial necrosis. In some cases these Q waves may disappear partially or completely in the evolution of the myocardial infarction. Five cases are described in whom complete Q wave regression and reappearance of R waves in the ...

In acute coronary syndromes the development of pathological Q waves is usually taken as evidence of established myocardial infarction (MI). We describe two patients with suspected acute MI who developed transient pathological Q waves. Cardiac enzymes were normal and cardiac catheterisation showed severe proximal coronary disease. Recognition of 'non-infarction' Q ...