Several critical clinical applications of magnetocardiography(MCG)involve its T wave.The T wave’s accuracy directly affects the diagnostic accuracy of MCG for ischemic heart disease and arrhythmogenic.Tunnel magnetor...Several critical clinical applications of magnetocardiography(MCG)involve its T wave.The T wave’s accuracy directly affects the diagnostic accuracy of MCG for ischemic heart disease and arrhythmogenic.Tunnel magnetoresistance(TMR)attracts attention as a new MCG measurement technique.However,the T waves measured by TMR are often drowned in noise.The accuracy of T waves needs to be discussed to determine the clinical value of MCG measured by TMR.This study uses an improved empirical mode decomposition(EMD)algorithm and averaging to eliminate the noise in the MCG measured by TMR.The MCG signals measured by TMR are compared with MCG measured by the optically pumped magnetometer(OPM)to judge its accuracy.Using the MCG measured by OPM as a reference,the relative errors in time and amplitude of the T wave measured by TMR are 3.4%and 1.8%,respectively.This is the first demonstration that TMR can accurately measure the time and amplitude of MCG T waves.The ability to provide reliable T wave data illustrates the significant clinical application value of TMR in MCG measurement.展开更多
Glucose metabolism is essential for heart physiology, especially in ischemic conditions. Anaerobic glycolysis participates along with aerobic fatty acid oxidation in generating energy supply, and the balance is shifte...Glucose metabolism is essential for heart physiology, especially in ischemic conditions. Anaerobic glycolysis participates along with aerobic fatty acid oxidation in generating energy supply, and the balance is shifted towards fatty acids. In the case of aerobic path restriction due to coronary artery disease (CAD), this ratio changes. The aim of the present research was to discover the aspects of glycolysis in cardiac electrophysiology.?We utilized the normalized (by average value) T wave amplitude deviation values, named the G criterion,?from high-resolution, 12-channel, 120-seconds-long electrocardiograms,?which were obtained using DACG technology. The calculated G criterion allows a quantitative assessment of the ischemic process and corresponds to the functional class (FC) according to the Canadian cardiovascular classification. We examined 22 healthy people and 79 proven CAD patients: 24 II FC, 40 III FC and 15 IV FC by original ECG and fasting blood sugar tests. A strong correlation was found between the average G criterion from all 12 channels and the level of fasting blood sugar (r = +0.88). In the control group, blood sugar levels were 91 ± 6.5 mg/dl, II FC 103 ± 14.8 mg/dl (p < 0.01), III FC 113 ± 23.4 mg/dl (p < 0.001), and IV FC 152 ± 42.4 (p < 0.001). Moreover, the correlation factor (average G criterion and blood sugar) was strong and positive in each group: control +0.72, II FC +0.83, III FC +0.76, and IV FC +0.89. For the first time, heart electrical activity from the ECG curve was associated with high glucose level as one of the main CAD risk factors. The presence of such dependence of increased blood sugar level from the severity of the ischemic process in the myocardium indicates that hyperglycemic reaction is adaptive and can accelerate the anaerobic glycolysis for energy demand compensation in heart muscle.展开更多
Two OBS arrays were deployed in the southern Okinawa Trough.Some of the OBS records revealedmany earthquakes with intensive T waves but ambiguous body waves.A new method using T waves for epicenter locating was develo...Two OBS arrays were deployed in the southern Okinawa Trough.Some of the OBS records revealedmany earthquakes with intensive T waves but ambiguous body waves.A new method using T waves for epicenter locating was developed that was found to be as precise as the body wave method for locatingepicenters when T waves are clearly recorded.展开更多
There have been several methods for determining T wave-end. But none of them can overcome the difficulty from multiformity of ECG signal pattern. In this paper, a method for determining T wave-end using evolutionary a...There have been several methods for determining T wave-end. But none of them can overcome the difficulty from multiformity of ECG signal pattern. In this paper, a method for determining T wave-end using evolutionary algorithm (EA) is proposed. In this way, first, every characteristic parameter related to T wave-end is encoded to a string of codes, and adaptation function is constructed with the string of codes. Then choose the individual according to the adaptation function value and do genetic operation (reproduction, crossover and mutation), so as to produce offspring with more adaptation function value. Because of EA's autoadaptation and autoorganization character, it can trace ECG signal type and find the T wave-end automatically.Experiment results show that the error ratio of recognizing T wave-end using this method is much smaller than that using existing method.展开更多
Objectives: There is a high rate of sudden death in epilepsy patients, part of which is sudden cardiac death. By investigating ECG T wave alternans and Q-T dispersion changes of epilepsy patients, we may predict the p...Objectives: There is a high rate of sudden death in epilepsy patients, part of which is sudden cardiac death. By investigating ECG T wave alternans and Q-T dispersion changes of epilepsy patients, we may predict the possibility of the occurrence of sudden death and provide basis for clinical prevention. Methods: Selecting 587 cases of epilepsy patients as the study group, 672 same period cases of healthy persons as the control group;Analyzing the effect of epilepsy on ECG T wave alternans and Q-T dispersion with the standard 12 lead ECG. Results: The study group had a significantly prolonged Q-T dispersion and an increased incidence of T wave alternans than that of the control group;Compared with other seizure types, tonic clonic seizure and absence seizure had a significantly prolonged Q-T dispersion and an increased occurrence rate of T wave alternans. Conclusions: Epilepsy patients ECG T wave alternans and Q-T dispersion has higher abnormal rate, and are prone to sudden cardiac death;Routine ECG(RECG) T wave alternans and Q-T dispersion changes can provide guidance for clinical prevention of sudden unexpected death in epilepsy (SUDEP).展开更多
Objective To explore therelation between changes of T waves and left ventricular function in patients with Q - wave anterior wall MI. Methods 105 consecutive patients with Q-wave anterior wall MI were enrolled in this...Objective To explore therelation between changes of T waves and left ventricular function in patients with Q - wave anterior wall MI. Methods 105 consecutive patients with Q-wave anterior wall MI were enrolled in this study. These patients were divided into two groups according to the polarity of T wave at 6 months: negative T - wave group (n=45) and positive T-wave group (n = 60) . Electrocardiograms were recorded and echocardiogra-phy was performed on admission and at 6 months after anterior MI. Results The peak serum creatine ki-nase activity of negative T - wave group and positive T -wave group was (4158 ±2478) IU/L and (2868±2358) IU/L, respectively (P < 0. 05). Left ventricular function was better in positive T - wave group than negative T - wave group. Conclusion Earlier normalization of the precordial T waves was associated with greater improvement in LV function. The early presence of inverted T waves in leads with abnormal Q waves can be used to assess the degree of LV dysfunction.展开更多
Background Incomplete right bundle branch block （ICRBBB） is commonly associated with atrial septal defect （ASD）, but lacks sufficient diagnostic test characteristics. An abnormal T wave is also often observed in A...Background Incomplete right bundle branch block （ICRBBB） is commonly associated with atrial septal defect （ASD）, but lacks sufficient diagnostic test characteristics. An abnormal T wave is also often observed in ASD, with horizontal or inverted displacement of the proximal T wave limb in the right precordial leads, termed ＂defective T wave＂ （DTW）. Methods We examined the diagnostic test characteristics of combining ICRBBB with DTW as a new index to diagnose ASD. A total of 132 consecutive patients with ASD and 132 cases of age/gender-matched controls without ASD were enrolled. Results Sensitivities of DTW, ICRBBB, and both were 87.1%-87.9%. Specificities were 97.0%, 96.2%, and 100%, respectively. Positive predictive values were 1.3%, 1.1%, and 100.0% respectively, while negative predictive values were 99.9% for each. Conclusion Combining ICRBBB with DTW in electrocardiogram （ECG） as a new index significantly increased the specificity and positive predictive values while maintaining a high sensitivity in diagnosing ASD.展开更多
BACKGROUND Apical hypertrophic cardiomyopathy(AHCM)is a subtype of hypertrophic cardiomyopathy.Due to its location,the thickening of the left ventricular apex can be missed on echocardiography.Giant negative T waves(G...BACKGROUND Apical hypertrophic cardiomyopathy(AHCM)is a subtype of hypertrophic cardiomyopathy.Due to its location,the thickening of the left ventricular apex can be missed on echocardiography.Giant negative T waves(GNTs)in left-sided chest leads are the hallmark electrocardiogram(ECG)change of AHCM.CASE SUMMARY The first patient was a 68-year-old woman complaining of recurrent chest tightness persisting for more than 3 years.The second was a 59-year-old man complaining of spasmodic chest tightness persisting for more than 2 years.The third was a 55-year-old woman complaining of recurrent chest pain persisting for 4 mo.In all three cases,GNTs were observed several years prior to apical cardiac hypertrophy after other causes of T-wave inversion were ruled out.CONCLUSION Electrophysiological abnormalities of AHCM appear earlier than structural abnormalities,confirming the early predictive value of ECG for AHCM.展开更多
Background: Atrial fibrillation (AF) and T wave inversion (TWI) are occasionally found on pre-operative electrocardiograms (EKG) of patients with long standing hy-pertension (HTN) associated with left ventricular hype...Background: Atrial fibrillation (AF) and T wave inversion (TWI) are occasionally found on pre-operative electrocardiograms (EKG) of patients with long standing hy-pertension (HTN) associated with left ventricular hypertrophy (LVH). Each of these two pathologies, AF and LVH, can impose negative hemodynamic effects on the car-diac function. Case: We present a case of a patient with AF, TWI and long standing HTN that went into post-operative pulmonary edema. Conclusion: Even returning to base line poorly controlled hypertension, and even more so during a hypertensive cri-sis, their concurrent presence may inflict even more detrimental effect manifested by elevation of pulmonary venous pressure and pulmonary edema.展开更多
AIM: To describe the electrocardiographic(ECG) phenomena characterized by T-wave inversion in the precordial leads in adults and to highlight its differential diagnosis. METHODS: A retrospective chart review of 8 adul...AIM: To describe the electrocardiographic(ECG) phenomena characterized by T-wave inversion in the precordial leads in adults and to highlight its differential diagnosis. METHODS: A retrospective chart review of 8 adult patients who were admitted with ECG T-wave inversion in the anterior chest leads with or without prolongation of corrected QT(QTc) interval. They had different clinical conditions. Each patient underwent appropriate clinical assessment including investigation for myocardial involvement. Single and multimodality noninvasive, semi-invasive and invasive diagnostic approach were used to ascertain the diagnosis. The diagnostic assessment included biochemical investigation, cardiac and abdominal ultrasound, cerebral and chest computed tomography, nuclear medicine and coronary angiography.RESULTS: Eight adult subjects(5 females) with a mean age of 66 years(range 51 to 82) are analyzed. The etiology of T-wave inversion in the precordial leads were diverse. On admission, all patients had normal blood pressure and the ECG showed sinus rhythm. Five patients showed marked prolongation of the QTc interval. The longest QTc interval(639 ms) was found in the patient with pheochromocytoma. Giant T-wave inversion(≥ 10 mm) was found in pheochromocytoma followed by electroconvulsive therapy and finally ischemic heart disease. The deepest T-wave was measured in lead V3(5 ×). In 3 patients presented with mild T-wave inversion(patients 1, 5 and 4 mm), the QTc interval was not prolonged(432, 409 and 424 msec), respectively.CONCLUSION: T-wave inversion associated with or without QTc prolongation requires meticulous history taking, physical examination and tailored diagnostic modalities to reach rapid and correct diagnosis to establish appropriate therapeutic intervention.展开更多
Forward-/backward-facing steps in boundary-layer flows are often seen in engineering applications, and they have potential impacts on laminar-turbulent transition through scattering of the oncoming instability modes(e...Forward-/backward-facing steps in boundary-layer flows are often seen in engineering applications, and they have potential impacts on laminar-turbulent transition through scattering of the oncoming instability modes(e.g., Tollmien-Schlichting(T-S) waves). This issue is studied in the present paper by applying a local scattering framework, which is a rather generic mathematical framework on describing the mode scattering process. In this framework, a high-Reynolds-number triple-deck formalism is employed, and a transmission coefficient, defined as the ratio of the asymptotic amplitude of the instability mode downstream of the step to that upstream, is introduced. Through the systematical study, it has been found that both the forward-and backward-facing steps have a destabilizing effect on the oncoming T-S waves in subsonic boundary layers, this effect increases with the height of the step and/or the frequency of the T-S wave, and a backward-facing step(BFS) always has a greater impact than a forward-facing step(FFS). These facts agree with most of the previous investigations.However, one numerical study(WORNER, A., RIST, U., and WAGNER, S. Humps/steps influence on stability characteristics of two-dimensional laminar boundary layer. AIAA Journal, 41, 192–197(2003)), which was based on an ad-hoc configuration, showed an opposite impact of an FFS. Through the investigation on the specific configuration, it is revealed that the wrong conclusion was drawn by misinterpreting the numerical results.展开更多
Pipeline plays an indispensable role in process industries,because the progressing crack-like defects of in it may result in serious accidents and significant economic losses.Therefore,it is essential to detect the cr...Pipeline plays an indispensable role in process industries,because the progressing crack-like defects of in it may result in serious accidents and significant economic losses.Therefore,it is essential to detect the cracks occurred in pipelines.The axial crack-like defects in elbows with different angle are inspected by using the T(0,1)mode guided waves,in which different configurations including 45°,90°,135°and 180°(straight pipe)are considered respectively.Firstly,the detection sensitivity for different defect location is experimentally investigated.After that,finite element simulation is used to explore the propagation behaviors of T(0,1)mode in different bend structures.Simulation and experiment results show that the crack in different areas of the elbow can affect the detection sensitivity.It can be found that the detection sensitivity of crack in the middle area of the elbow is higher compared to the extrados and intrados of the elbow.Finally,the mode conversion is also investigated when the T(0,1)crosses the bend,and the results show that bend is a key factor to the mode conversion phenomenon which presents between the T(0,1)mode and F(1,2)mode.展开更多
Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in ...Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in this research field. In this article, I have, first, made a brief review on those developments and then introduced and summarized a unified and efficient method, global generalized reflection-transmission (abbreviated to R/T thereafter) matrices method, for synthetic seismograms in multi-layered media with irregular interfaces developed by the author [24~26]. As demonstrated in this article, this method could be regarded as an extension of the generalized R/T coefficients method for the horizontally layered case [2,5] to the layered media with irregularly shaped interfaces by incorporating the T matrices technique [27,28]. Because of the use of a recursive scheme in computing the global generalized R/T matrices, this method is efficient, particularly for the case with a large number of展开更多
T-wave alternans (TWA), consisting in an alternation of the electrocardiographic (ECG) repolarization segment (T-wave), is a promising index of the risk of sudden cardiac death. By definition, it is characterized by a...T-wave alternans (TWA), consisting in an alternation of the electrocardiographic (ECG) repolarization segment (T-wave), is a promising index of the risk of sudden cardiac death. By definition, it is characterized by a frequency component, termed fTWA, that matches half heart rate. The heart-rate adaptive match filter (AMF) based method is a technique for automatic TWA identification from the digital ECG. Aim of the present study was to provide a complete technical description of the filter able to explain its methodological principles. The AMF is usually realized as a 6th order Butterworth filter with a narrow (0.12 Hz) passing band centered in fTWA. It is applied in a bidirectional fashion, so that final filtering order is 12. While extracting the TWA component, the AMF simultaneously filters out every ECG component including noise and artefacts, and thus results are very robust. Goodness of the technique was tested using 8 synthetic ECG tracings corrupted by typical noisy factors, such as white random noise, baseline wanderings, heart-rate variability, and others. Six ECG tracings were affected by 100 μV TWA, whereas two were not. Results indicate that the AMF-based method is able to prevent false-positive and false-negative detections and, thus, represents a useful tool for a reliable TWA identification.展开更多
Presently T-wave alternans (TWA) has become a clinical index of non-invasive diagnosis for heart sudden death prediction, and detecting T-wave alternate accurately is particularly important. This paper introduces an a...Presently T-wave alternans (TWA) has become a clinical index of non-invasive diagnosis for heart sudden death prediction, and detecting T-wave alternate accurately is particularly important. This paper introduces an algorithm for detecting TWA using Poincare mapping method which is a technique for nonlinear dynamic systems to display periodic behavior. Sample series of beat to beat cycles were selected to prepare Poincare mapping method. Vector Angle Index (VAI), which is the mean of the difference between θi (the angle between the line connecting the i point to the origin and the X axis) and 45 degrees was used to present the presence or absence of TWA. The value of 0.9 rad ≤ VAI ≤ 1.03 rad is accepted as a level determinative for presence of TWA. VAI via Poincare mapping method (PM) is used for correlation analysis with T-wave alternans voltage (Vtwa) by way of the spectral method (SM). The cross-correlation coefficient between Vtwa and VAI is γ = 0.8601. The algorithm can identify the absence and presence of TWA accurately and provide idea for further study of TWA-PM.展开更多
Objective: To explore the application value of electrocardiograph (ECG) T-wave Alternans (TWA) anomaly in acute stage of intracerebral hemorrhage patients. Methods: We choose 1175 intracerebral hemorrhage patients who...Objective: To explore the application value of electrocardiograph (ECG) T-wave Alternans (TWA) anomaly in acute stage of intracerebral hemorrhage patients. Methods: We choose 1175 intracerebral hemorrhage patients whose conventional 12-lead ECG has TWA in our hospital from January 2011 to December 2015, 751 patients without TWA in the same period as the control group, compared the volume of intracerebral hemorrhage, bleeding site and mortality between the 2 groups. Results: In TWA group, 247 cases died, 361 cases with massive intracerebral hemorrhage, 298 cases with brain stem hemorrhage;in TWA negative group (control group), 41 cases died, 93 cases with massive brain hemorrhage, 64 cases with brain stem hemorrhage. There are statistical differences between two groups (P Conclusion: The occurrence of TWA is significantly related to the volume of bleeding, the bleeding site and mortality, and can be used as an important parameter in the prognosis of intracerebral hemorrhage.展开更多
Petrophysical proprieties such as porosity, density, permeability and saturation have a marked impact on acoustic proprieties of rocks. Hence, there has been recently a strong incentive to use new geophysical techniqu...Petrophysical proprieties such as porosity, density, permeability and saturation have a marked impact on acoustic proprieties of rocks. Hence, there has been recently a strong incentive to use new geophysical techniques to invert such properties from seismic or sonic measurements for rocks characterization. The P-wave velocity, which is non-destructtive and easy method to apply in both field and laboratory conditions, has increasingly been conducted to determine the geotechnical properties of rock materials. The P-wave velocity of a rock is closely related to the intact rock properties, and been measuring the velocity in rock masses describes the rock structure and texture. The present work deals with the use of a simple and non-destructive technique, ultrasonic velocity, to predict the porosity and density of calcarenite rocks that are characteristic in historical monument. The ultrasonic test is based on measuring the propagation time of a P-wave in the longitudinal direction. Good correlations between P-wave velocity, porosity and density were found, which indicated them as an appropriate technique for estimating the porosity and density.展开更多
Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms an...Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.展开更多
基金supported by the Suzhou Tsinghua innovation leading action project(Grant No.2016SZ0217)the National Key Research and Development Program of China(Grant No.2016YFB0500902)。
文摘Several critical clinical applications of magnetocardiography(MCG)involve its T wave.The T wave’s accuracy directly affects the diagnostic accuracy of MCG for ischemic heart disease and arrhythmogenic.Tunnel magnetoresistance(TMR)attracts attention as a new MCG measurement technique.However,the T waves measured by TMR are often drowned in noise.The accuracy of T waves needs to be discussed to determine the clinical value of MCG measured by TMR.This study uses an improved empirical mode decomposition(EMD)algorithm and averaging to eliminate the noise in the MCG measured by TMR.The MCG signals measured by TMR are compared with MCG measured by the optically pumped magnetometer(OPM)to judge its accuracy.Using the MCG measured by OPM as a reference,the relative errors in time and amplitude of the T wave measured by TMR are 3.4%and 1.8%,respectively.This is the first demonstration that TMR can accurately measure the time and amplitude of MCG T waves.The ability to provide reliable T wave data illustrates the significant clinical application value of TMR in MCG measurement.
文摘Glucose metabolism is essential for heart physiology, especially in ischemic conditions. Anaerobic glycolysis participates along with aerobic fatty acid oxidation in generating energy supply, and the balance is shifted towards fatty acids. In the case of aerobic path restriction due to coronary artery disease (CAD), this ratio changes. The aim of the present research was to discover the aspects of glycolysis in cardiac electrophysiology.?We utilized the normalized (by average value) T wave amplitude deviation values, named the G criterion,?from high-resolution, 12-channel, 120-seconds-long electrocardiograms,?which were obtained using DACG technology. The calculated G criterion allows a quantitative assessment of the ischemic process and corresponds to the functional class (FC) according to the Canadian cardiovascular classification. We examined 22 healthy people and 79 proven CAD patients: 24 II FC, 40 III FC and 15 IV FC by original ECG and fasting blood sugar tests. A strong correlation was found between the average G criterion from all 12 channels and the level of fasting blood sugar (r = +0.88). In the control group, blood sugar levels were 91 ± 6.5 mg/dl, II FC 103 ± 14.8 mg/dl (p < 0.01), III FC 113 ± 23.4 mg/dl (p < 0.001), and IV FC 152 ± 42.4 (p < 0.001). Moreover, the correlation factor (average G criterion and blood sugar) was strong and positive in each group: control +0.72, II FC +0.83, III FC +0.76, and IV FC +0.89. For the first time, heart electrical activity from the ECG curve was associated with high glucose level as one of the main CAD risk factors. The presence of such dependence of increased blood sugar level from the severity of the ischemic process in the myocardium indicates that hyperglycemic reaction is adaptive and can accelerate the anaerobic glycolysis for energy demand compensation in heart muscle.
文摘Two OBS arrays were deployed in the southern Okinawa Trough.Some of the OBS records revealedmany earthquakes with intensive T waves but ambiguous body waves.A new method using T waves for epicenter locating was developed that was found to be as precise as the body wave method for locatingepicenters when T waves are clearly recorded.
基金Supported by the National Nature Science Foundation of China (No. 39870211, 39970219)
文摘There have been several methods for determining T wave-end. But none of them can overcome the difficulty from multiformity of ECG signal pattern. In this paper, a method for determining T wave-end using evolutionary algorithm (EA) is proposed. In this way, first, every characteristic parameter related to T wave-end is encoded to a string of codes, and adaptation function is constructed with the string of codes. Then choose the individual according to the adaptation function value and do genetic operation (reproduction, crossover and mutation), so as to produce offspring with more adaptation function value. Because of EA's autoadaptation and autoorganization character, it can trace ECG signal type and find the T wave-end automatically.Experiment results show that the error ratio of recognizing T wave-end using this method is much smaller than that using existing method.
文摘Objectives: There is a high rate of sudden death in epilepsy patients, part of which is sudden cardiac death. By investigating ECG T wave alternans and Q-T dispersion changes of epilepsy patients, we may predict the possibility of the occurrence of sudden death and provide basis for clinical prevention. Methods: Selecting 587 cases of epilepsy patients as the study group, 672 same period cases of healthy persons as the control group;Analyzing the effect of epilepsy on ECG T wave alternans and Q-T dispersion with the standard 12 lead ECG. Results: The study group had a significantly prolonged Q-T dispersion and an increased incidence of T wave alternans than that of the control group;Compared with other seizure types, tonic clonic seizure and absence seizure had a significantly prolonged Q-T dispersion and an increased occurrence rate of T wave alternans. Conclusions: Epilepsy patients ECG T wave alternans and Q-T dispersion has higher abnormal rate, and are prone to sudden cardiac death;Routine ECG(RECG) T wave alternans and Q-T dispersion changes can provide guidance for clinical prevention of sudden unexpected death in epilepsy (SUDEP).
文摘Objective To explore therelation between changes of T waves and left ventricular function in patients with Q - wave anterior wall MI. Methods 105 consecutive patients with Q-wave anterior wall MI were enrolled in this study. These patients were divided into two groups according to the polarity of T wave at 6 months: negative T - wave group (n=45) and positive T-wave group (n = 60) . Electrocardiograms were recorded and echocardiogra-phy was performed on admission and at 6 months after anterior MI. Results The peak serum creatine ki-nase activity of negative T - wave group and positive T -wave group was (4158 ±2478) IU/L and (2868±2358) IU/L, respectively (P < 0. 05). Left ventricular function was better in positive T - wave group than negative T - wave group. Conclusion Earlier normalization of the precordial T waves was associated with greater improvement in LV function. The early presence of inverted T waves in leads with abnormal Q waves can be used to assess the degree of LV dysfunction.
文摘Background Incomplete right bundle branch block （ICRBBB） is commonly associated with atrial septal defect （ASD）, but lacks sufficient diagnostic test characteristics. An abnormal T wave is also often observed in ASD, with horizontal or inverted displacement of the proximal T wave limb in the right precordial leads, termed ＂defective T wave＂ （DTW）. Methods We examined the diagnostic test characteristics of combining ICRBBB with DTW as a new index to diagnose ASD. A total of 132 consecutive patients with ASD and 132 cases of age/gender-matched controls without ASD were enrolled. Results Sensitivities of DTW, ICRBBB, and both were 87.1%-87.9%. Specificities were 97.0%, 96.2%, and 100%, respectively. Positive predictive values were 1.3%, 1.1%, and 100.0% respectively, while negative predictive values were 99.9% for each. Conclusion Combining ICRBBB with DTW in electrocardiogram （ECG） as a new index significantly increased the specificity and positive predictive values while maintaining a high sensitivity in diagnosing ASD.
文摘BACKGROUND Apical hypertrophic cardiomyopathy(AHCM)is a subtype of hypertrophic cardiomyopathy.Due to its location,the thickening of the left ventricular apex can be missed on echocardiography.Giant negative T waves(GNTs)in left-sided chest leads are the hallmark electrocardiogram(ECG)change of AHCM.CASE SUMMARY The first patient was a 68-year-old woman complaining of recurrent chest tightness persisting for more than 3 years.The second was a 59-year-old man complaining of spasmodic chest tightness persisting for more than 2 years.The third was a 55-year-old woman complaining of recurrent chest pain persisting for 4 mo.In all three cases,GNTs were observed several years prior to apical cardiac hypertrophy after other causes of T-wave inversion were ruled out.CONCLUSION Electrophysiological abnormalities of AHCM appear earlier than structural abnormalities,confirming the early predictive value of ECG for AHCM.
文摘Background: Atrial fibrillation (AF) and T wave inversion (TWI) are occasionally found on pre-operative electrocardiograms (EKG) of patients with long standing hy-pertension (HTN) associated with left ventricular hypertrophy (LVH). Each of these two pathologies, AF and LVH, can impose negative hemodynamic effects on the car-diac function. Case: We present a case of a patient with AF, TWI and long standing HTN that went into post-operative pulmonary edema. Conclusion: Even returning to base line poorly controlled hypertension, and even more so during a hypertensive cri-sis, their concurrent presence may inflict even more detrimental effect manifested by elevation of pulmonary venous pressure and pulmonary edema.
文摘AIM: To describe the electrocardiographic(ECG) phenomena characterized by T-wave inversion in the precordial leads in adults and to highlight its differential diagnosis. METHODS: A retrospective chart review of 8 adult patients who were admitted with ECG T-wave inversion in the anterior chest leads with or without prolongation of corrected QT(QTc) interval. They had different clinical conditions. Each patient underwent appropriate clinical assessment including investigation for myocardial involvement. Single and multimodality noninvasive, semi-invasive and invasive diagnostic approach were used to ascertain the diagnosis. The diagnostic assessment included biochemical investigation, cardiac and abdominal ultrasound, cerebral and chest computed tomography, nuclear medicine and coronary angiography.RESULTS: Eight adult subjects(5 females) with a mean age of 66 years(range 51 to 82) are analyzed. The etiology of T-wave inversion in the precordial leads were diverse. On admission, all patients had normal blood pressure and the ECG showed sinus rhythm. Five patients showed marked prolongation of the QTc interval. The longest QTc interval(639 ms) was found in the patient with pheochromocytoma. Giant T-wave inversion(≥ 10 mm) was found in pheochromocytoma followed by electroconvulsive therapy and finally ischemic heart disease. The deepest T-wave was measured in lead V3(5 ×). In 3 patients presented with mild T-wave inversion(patients 1, 5 and 4 mm), the QTc interval was not prolonged(432, 409 and 424 msec), respectively.CONCLUSION: T-wave inversion associated with or without QTc prolongation requires meticulous history taking, physical examination and tailored diagnostic modalities to reach rapid and correct diagnosis to establish appropriate therapeutic intervention.
基金supported by the National Natural Science Foundation of China(Nos.11472189 and11772224)
文摘Forward-/backward-facing steps in boundary-layer flows are often seen in engineering applications, and they have potential impacts on laminar-turbulent transition through scattering of the oncoming instability modes(e.g., Tollmien-Schlichting(T-S) waves). This issue is studied in the present paper by applying a local scattering framework, which is a rather generic mathematical framework on describing the mode scattering process. In this framework, a high-Reynolds-number triple-deck formalism is employed, and a transmission coefficient, defined as the ratio of the asymptotic amplitude of the instability mode downstream of the step to that upstream, is introduced. Through the systematical study, it has been found that both the forward-and backward-facing steps have a destabilizing effect on the oncoming T-S waves in subsonic boundary layers, this effect increases with the height of the step and/or the frequency of the T-S wave, and a backward-facing step(BFS) always has a greater impact than a forward-facing step(FFS). These facts agree with most of the previous investigations.However, one numerical study(WORNER, A., RIST, U., and WAGNER, S. Humps/steps influence on stability characteristics of two-dimensional laminar boundary layer. AIAA Journal, 41, 192–197(2003)), which was based on an ad-hoc configuration, showed an opposite impact of an FFS. Through the investigation on the specific configuration, it is revealed that the wrong conclusion was drawn by misinterpreting the numerical results.
基金supported by the National Natural Science Foundation of China(Nos.51575185,51175178)
文摘Pipeline plays an indispensable role in process industries,because the progressing crack-like defects of in it may result in serious accidents and significant economic losses.Therefore,it is essential to detect the cracks occurred in pipelines.The axial crack-like defects in elbows with different angle are inspected by using the T(0,1)mode guided waves,in which different configurations including 45°,90°,135°and 180°(straight pipe)are considered respectively.Firstly,the detection sensitivity for different defect location is experimentally investigated.After that,finite element simulation is used to explore the propagation behaviors of T(0,1)mode in different bend structures.Simulation and experiment results show that the crack in different areas of the elbow can affect the detection sensitivity.It can be found that the detection sensitivity of crack in the middle area of the elbow is higher compared to the extrados and intrados of the elbow.Finally,the mode conversion is also investigated when the T(0,1)crosses the bend,and the results show that bend is a key factor to the mode conversion phenomenon which presents between the T(0,1)mode and F(1,2)mode.
文摘Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in this research field. In this article, I have, first, made a brief review on those developments and then introduced and summarized a unified and efficient method, global generalized reflection-transmission (abbreviated to R/T thereafter) matrices method, for synthetic seismograms in multi-layered media with irregular interfaces developed by the author [24~26]. As demonstrated in this article, this method could be regarded as an extension of the generalized R/T coefficients method for the horizontally layered case [2,5] to the layered media with irregularly shaped interfaces by incorporating the T matrices technique [27,28]. Because of the use of a recursive scheme in computing the global generalized R/T matrices, this method is efficient, particularly for the case with a large number of
文摘T-wave alternans (TWA), consisting in an alternation of the electrocardiographic (ECG) repolarization segment (T-wave), is a promising index of the risk of sudden cardiac death. By definition, it is characterized by a frequency component, termed fTWA, that matches half heart rate. The heart-rate adaptive match filter (AMF) based method is a technique for automatic TWA identification from the digital ECG. Aim of the present study was to provide a complete technical description of the filter able to explain its methodological principles. The AMF is usually realized as a 6th order Butterworth filter with a narrow (0.12 Hz) passing band centered in fTWA. It is applied in a bidirectional fashion, so that final filtering order is 12. While extracting the TWA component, the AMF simultaneously filters out every ECG component including noise and artefacts, and thus results are very robust. Goodness of the technique was tested using 8 synthetic ECG tracings corrupted by typical noisy factors, such as white random noise, baseline wanderings, heart-rate variability, and others. Six ECG tracings were affected by 100 μV TWA, whereas two were not. Results indicate that the AMF-based method is able to prevent false-positive and false-negative detections and, thus, represents a useful tool for a reliable TWA identification.
文摘Presently T-wave alternans (TWA) has become a clinical index of non-invasive diagnosis for heart sudden death prediction, and detecting T-wave alternate accurately is particularly important. This paper introduces an algorithm for detecting TWA using Poincare mapping method which is a technique for nonlinear dynamic systems to display periodic behavior. Sample series of beat to beat cycles were selected to prepare Poincare mapping method. Vector Angle Index (VAI), which is the mean of the difference between θi (the angle between the line connecting the i point to the origin and the X axis) and 45 degrees was used to present the presence or absence of TWA. The value of 0.9 rad ≤ VAI ≤ 1.03 rad is accepted as a level determinative for presence of TWA. VAI via Poincare mapping method (PM) is used for correlation analysis with T-wave alternans voltage (Vtwa) by way of the spectral method (SM). The cross-correlation coefficient between Vtwa and VAI is γ = 0.8601. The algorithm can identify the absence and presence of TWA accurately and provide idea for further study of TWA-PM.
文摘Objective: To explore the application value of electrocardiograph (ECG) T-wave Alternans (TWA) anomaly in acute stage of intracerebral hemorrhage patients. Methods: We choose 1175 intracerebral hemorrhage patients whose conventional 12-lead ECG has TWA in our hospital from January 2011 to December 2015, 751 patients without TWA in the same period as the control group, compared the volume of intracerebral hemorrhage, bleeding site and mortality between the 2 groups. Results: In TWA group, 247 cases died, 361 cases with massive intracerebral hemorrhage, 298 cases with brain stem hemorrhage;in TWA negative group (control group), 41 cases died, 93 cases with massive brain hemorrhage, 64 cases with brain stem hemorrhage. There are statistical differences between two groups (P Conclusion: The occurrence of TWA is significantly related to the volume of bleeding, the bleeding site and mortality, and can be used as an important parameter in the prognosis of intracerebral hemorrhage.
文摘Petrophysical proprieties such as porosity, density, permeability and saturation have a marked impact on acoustic proprieties of rocks. Hence, there has been recently a strong incentive to use new geophysical techniques to invert such properties from seismic or sonic measurements for rocks characterization. The P-wave velocity, which is non-destructtive and easy method to apply in both field and laboratory conditions, has increasingly been conducted to determine the geotechnical properties of rock materials. The P-wave velocity of a rock is closely related to the intact rock properties, and been measuring the velocity in rock masses describes the rock structure and texture. The present work deals with the use of a simple and non-destructive technique, ultrasonic velocity, to predict the porosity and density of calcarenite rocks that are characteristic in historical monument. The ultrasonic test is based on measuring the propagation time of a P-wave in the longitudinal direction. Good correlations between P-wave velocity, porosity and density were found, which indicated them as an appropriate technique for estimating the porosity and density.
文摘Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.
