Fetal electrocardiogram signal extraction and analysis method combining fast independent component analysis algorithm and convolutional neural network / 生物医学工程学杂志

Fetal electrocardiogram (ECG) signals provide important clinical information for early diagnosis and intervention of fetal abnormalities. In this paper, we propose a new method for fetal ECG signal extraction and analysis. Firstly, an improved fast independent component analysis method and singular value decomposition algorithm are combined to extract high-quality fetal ECG signals and solve the waveform missing problem. Secondly, a novel convolutional neural network model is applied to identify the QRS complex waves of fetal ECG signals and effectively solve the waveform overlap problem. Finally, high quality extraction of fetal ECG signals and intelligent recognition of fetal QRS complex waves are achieved. The method proposed in this paper was validated with the data from the PhysioNet computing in cardiology challenge 2013 database of the Complex Physiological Signals Research Resource Network. The results show that the average sensitivity and positive prediction values of the extraction algorithm are 98.21% and 99.52%, respectively, and the average sensitivity and positive prediction values of the QRS complex waves recognition algorithm are 94.14% and 95.80%, respectively, which are better than those of other research results. In conclusion, the algorithm and model proposed in this paper have some practical significance and may provide a theoretical basis for clinical medical decision making in the future.

Fibrilación auricular por vía accesoria con patrón de preexcitación ventricular: Informe de un caso / Atrial fibrillation by accessory pathway with pattern of ventricular pre-excitation: A case report

RESUMEN La fibrilación auricular por vía accesoria es una peligrosa enfermedad que puede provocar muerte súbita; es poco frecuente y necesita una conducta exacta, mucho más si aparece un patrón de preexcitación ventricular. Se presenta el caso de un adolescente masculino de 17 años de edad y piel blanca, con antecedentes de palpitaciones cortas a esfuerzos moderados y pérdida ocasional del conocimiento de breve duración, sin otra sintomatología asociada. Al momento del ingreso presenta un cuadro de palpitaciones, fatiga, palidez e hipotensión arterial, y en el electrocardiograma se observa una taquicardia con QRS ancho, irregular, con onda delta y frecuencia ventricular rápida, que fue interpretada como fibrilación auricular preexcitada. Se realizó cardioversión eléctrica sincronizada al QRS con 100 julios y se logró restaurar el ritmo sinusal con patrón electrocardiográfico de preexitación ventricular (síndrome de Wolff-Parkinson-White).

ABSTRACT Atrial fibrillation by accessory pathway is a dangerous disease that can cause sudden death, it is rare and it needs a careful management, even more, if a pattern of ventricular pre-excitation appears. The case of a white skin 17-year-old teenager with a history of short palpitations at moderate effort, and occasional loss of consciousness of short duration, without other associated symptoms, is presented. At the moment of admission, he presents palpitations, fatigue, pallor and low blood pressure; in the electrocardiogram a tachycardia with wide, irregular QRS, with delta wave and rapid ventricular rate is observed, which was interpreted as pre-excited atrial fibrillation. Synchronized electrical cardioversion to QRS with 100 joules was performed, and sinus rhythm was restored with electrocardiographic pattern of ventricular pre-excitation (Wolff-Parkinson-White syndrome).

Diagnóstico diferencial de las taquicardias de complejo ancho: un desafío permanente / Wide QRS tachycardia: a diagnostic challenge

El diagnóstico electrocardiográfico correcto de la causa de una taquicardia de complejo QRS ancho (TCA) es fundamental, ya que tanto el manejo, como el pronóstico del paciente, es diferente según su etiología, y define el estudio que debemos realizar. Numerosos criterios y algoritmos han sido descritos para diferenciar el origen de estas taquicardias. Sin embargo, muchos de estos son complejos y difíciles de aplicar para el médico menos experimentado. Esto es particularmente importante en los servicios de emergencia, donde se necesita una definición rápida que permita un manejo agudo apropiado. En la presente revisión analizamos los diferentes mecanismos de las TCA y los principales criterios diagnósticos en el ECG, reforzando, especialmente, aquellos de aplicación rápida y de alto rendimiento diagnóstico.

The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis of the patient. The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis is different according to its etiology and defines the study that we should perform. Numerous criteria and algorithms have been described to differentiate the origin of these tachycardias. However, many of these are complex and difficult to apply to the less experienced doctor. This is particularly important in emergency rooms, where a rapid definition is needed to allow proper therapy. In this review we analyze the different mechanisms of WCT and the main EKG diagnostic criteria, emphasizing those which can be applied rapidly and have high diagnostic value.

A case of ventricular tachycardia precipitated by caffeine: a rare occurrence

The effects of caffeine vary according to the dose and patient. Thus, there is no bright line defining thresholds. Here, we present an unusual case of ventricular tachycardia precipitated by a dose of 450-500 mg of caffeine in a healthy 33-year-old man.

Arritmias provocadas por ondansetrón: Presentación de un caso / Arrhythmias caused by ondansetron: Case report

RESUMEN El ondansetrón se usa para prevenir las náuseas y los vómitos causados por la quimioterapia, radioterapia y cirugías, pertenece a los antagonistas de receptores de serotonina 5-HT3, una sustancia natural que puede causar náuseas y vómitos, y bloquea su acción. El ondansetrón viene envasado en forma de tabletas de desintegración rápida, como una solución para tomar por vía oral y en ámpulas, para su uso parenteral. Se presenta el caso de una paciente de 67 años de edad con diagnóstico de carcinoma de mama, a la cual se realizó mastectomía radical con vaciamiento axilar, y recibió quimioterapia con adriamicina, ciclofosfamida y paclitaxel; así como ondansetrón para tratar las náuseas y vómitos. La paciente presentó una taquicardia con QRS ancho después de utilizar el fármaco.

ABSTRACT The ondansetron is used to prevent nausea and vomiting caused by chemotherapy, radiotherapy and surgery, belonging to the serotonin 5-HT3 receptor antagonists, a natural substance that can cause nausea and vomiting, and it blocks its action. The ondansetron is packaged in the form of rapid disintegration tablets, as a solution to be taken orally and in ampules, for parenteral use. The case of a 67-year-old female patient is presented, with a diagnosis of breast carcinoma, who underwent radical mastectomy with axillary dissection was performed, and who received chemotherapy with adriamycin, cyclophosphamide and paclitaxel; as well as ondansetron to treat nausea and vomiting. The patient presented a wide QRS complex tachycardia after taking the drug.

The role of frontal plane cardiac axis shift in the diagnosis of wide QRS tachycardia / 实用医学杂志

Objective To explore the value of axis shift between the baseline normal sinus rhythm (NSR) and WCT in diagnosis of wide QRS-complex tachycardia (WCT). Methods 390 surface ECGs of 186 patients with WCT were obtained from April 2012 to April 2018 at Ningbo Medical Center Lihuili Hospital at which the arrhythmia diagnosis was proven by intracardiac electrophysiological study. The axis shift between the baseline NSR and WCT was calculated by table lookup method. Then we analyzed the role of axis shift in diagnosis of WCT. Results Among the 186 patients with WCT, 147 (79.03％) were ventricular tachycardia (VT) , and 39 (20.97％) were supraventricual tachycardia (SVT) with conduction abnormalities. In the 95％ confidence interval, the axis shift showed an outstanding discrimination performance. The area under the ROC curve is 0.708 (0.579-0.817, P =0.007). Compared with left axis deviation, right axis deviation, the right axis deviation of LBBB morphology, the axis shift> 68 degree is more sensitive (53.06％) , and the specificity (91.43％) is also more desirable. Moreover, if the axis shift set> 130 degree, the specificity can reach 100％, and the sensitivity (12.24％) is equivalent to northwestern axis. Conclusion A significant axis shift between the baseline NRS and WCT can distinguish WCT accurately. Given the ease of grasping, it can probably be feasible to popularize as a routine diagnosis method for WCT in primary hospitals.

Correlation Between Blood Volume And Amplitude Of Qrs Complex In Young Healthy Individuals

Background Hemodynamic instability following trauma is perhaps the commonest cause of loss of life. The standard vital signsused to determine hemodynamic status are static measurements rather than dynamic, and may not truly reflect early volume loss. The Brody effect proposes a direct relationship between the QRS complex voltage and ventricular blood volume, a theory which has been supported by both human and animal studies. Aim To correlate blood volume and amplitude of QRS complex. Material and Methods Lead II ECG was recorded for 1 min in 56 healthy adult male volunteers (20–40 years) using the student Physiograph(Bio Devices). The amplitude of the largest QRS complex was measured in µV. Blood volume (in litres) was calculated by Nadler’s method using height and weight. RESULTS: Blood volume showed positive correlation with QRS amplitude.

QRS complex

The QRS complex is a group of waves in the electrocardiogram (ECG), and represents ventricular activation. It usually consists of three wave forms. The Q wave is an initial negative wave at the onset of the QRS complex. The R wave is the first positive wave in the QRS complex, and appears at the onset of the QRS complex or following a Q wave. The S wave is a second negative wave in the QRS complex. The morphology of the QRS complex is useful in interpreting a 12-lead ECG because it provides clinical information regarding heart rate, QRS axis, heart position, rotation, and abnormal conduction in the ventricles.

Analysis of 139 patients with wide QRS complex tachycardia in emergency departent / 中华急诊医学杂志

Objective To study the clinical characterics of 139 patients with wide QRS complex tachycardia.Methods Retrospective analysis was performed on 139 patients with QRS wave tachycardia treated by radiofrequency ablation at TEDA International Cardiovascular Hospital.The patients were divided into supra-ventricular tachycardia with intra-ventricular aberrany group (group A,n =84) and ventricular tachycardia (group B,n =55).The clinical data,electrocardiogram (ECG) and echocardiographic features between the two groups were compared.Results There was no statistical significance between the two groups in terms of gender,height,weight and ventricular rate (P ＞ 0.05).The difference in the course of disease,blood pressure,age,QRS duration,left ventricular diameter by echocardiography and ejection fraction was statistically significant (P ＜ 0.05).Radiofrequency ablation result showed that 81 (96.4％) cases were successful in group A,and 37 (67.3％) cases were successful in group B.The difference in the success rate was statistically significant (P ＜0.05).After 1 year of follow-up,4 (2.9％) cases in group A were recurred,13 (23.6％) cases in group B were recurred.The difference in the recurrence rate was statistically significant.Conclusion The wide QRS wave tachycardia is often accompanied with left ventricular diameter enlargement and left ventricular ejection fraction reduction,The success rate of radiofrequency ablation is low,and the recurrence rate is high when diagnosis is ventricular tachycardia.

Effect of QRS duration on left ventricular function and synchrony in complete left bundle branch block patients with preserved left ventricle ejection fraction using two-dimensional speckle tracking echocardiography / 中国医学影像技术

Objective To evaluate the value of two-dimensional speckle tracking echocardiography (2D-STE) in assessing left ventricular systolic function,diastolic function and synchrony with different QRS complex duration in complete left bundle branch block (CLBBB) patients with preserved left ventricle ejection fraction (LVEF).Methods A total of 44 patients with CLBBB and LVEF≥50％ were included.All the patients were divided into two groups based on QRS duration,QRS＞150 ms as wide QRS group and 120 ms≤QRS≤150 ms as narrow QRS group.And 30 healthy people were included as control group.Two-dimensional echocardiography and 2D-STE were performed.Ieft ventricle longitudinal peak stain of global,septum and free wall (LS-G,LS-Sept,LS-Lat),standard deviation of time to peak systolic strain for the 18 left ventricular segments (SDt) and index of left yen tricular diastolic function (EDT,E/A and E/e') were measured.Results SDt values of wide QRS group and narrow QRS group were significantly higher than that of control group (both P＜0.01).And SDt of wide QRS group was significantly higher than that of narrow QRS group (P＜0.05).LVEF and LS-G in wide QRS group were significantly lower than those in both narrow QRS group and control group (all P＜ 0.05),while there was no significant difference between narrow QRS group and control group (all P＞0.05).The LS-Sept in wide QRS group and narrow QRS group were both lower than that of control group (both P ＜0.01).And LS-Sept in wide QRS group was lower than that of narrow QRS group (P＜0.01).LS-Lat in narrow QRS group was separately higher than those of both wide QRS group and control group (both P＜0.05),while there was no significant difference of LS-Lat between wide QRS group and control group (P＞0.05).Compared with control group,E/A and EDT decreased and of E/e' increased in both wide QRS group and narrow QRS group (all P＜0.05).While there was no significant difference between wide QRS group and narrow QRS group (all P＞0.05).Conclusion In patients of wide QRS CLBBB with preserved LVEF,left ventricular systolic,diastolic function and synchrony decrease,while left ventricular systolic function of patients with narrow QRS do not significantly decrease.

Preexcitation Syndrome with a Mahaim-type Accessory Pathway

Wide QRS complex tachycardia with a left bundle branch block pattern can be caused by supraventricular tachycardia with aberrant conduction, preexcitation syndrome mediated through a right-sided accessory pathway, and/or ventricular tachycardia. The use of atrial pacing maneuvers can be beneficial for unmasking minimal preexcitation to differentiate between these conditions. Here, we report a case of successful radiofrequency catheter ablation of a Mahaim fiber in a patient with wide QRS complex tachycardia.

Taquicardia de complejos QRS anchos y patrón morfológico de "aberración" / Wide QRS complex tachycardia and morphological pattern of "aberration"

ResumenSe presenta el caso de un paciente portador de enfermedad arterial coronaria que presentó varios episodios de taqui cardia regular de complejos anchos, de múltiples morfologías. Se discute el diagnóstico electrocardiográfico diferencial.

AbstractWe present the case of a coronary artery disease patient who presented with several episodes of regular wide complex tachycardia with multiple morphologies. Differential electrocardiographic diagnosis is discussed.

The inf1uences of QRS comp1ex duration in patients with chronic 1eft heart fai1ure / 中国介入心脏病学杂志

Objective To study the effects of QRS-complex duration of patients with chronic left heart failure on their in-hospital prognosis. Methods Total 174 patients admitted for chronic left heart failure ( New York Heart Association class 3 and 4 ) from January 2014 to June 2015 were enrolled the study. They were divided into two groups according to the QRS duration at admission:normal QRS duration group (QRS ≤120 ms, n=145) and prolonged QRS group (QRS ﹥120 ms, n=29). The differences of clinical characteristics and incidences of exacerbated left heart failure, fatal arrhythmias and cardiac death during hospitalization were compared between the two groups. The influences of QRS duration on in-hospital adverse cardiovascular events was analyzed by logistic regression. Resu1ts The proportion of males (75. 9% vs. 24. 1%, P=0. 001), plasma B-type natriuretic peptide (BNP) (7. 1 ± 0. 8 vs. 6. 6 ± 1. 0, P=0. 02), left ventricular end diastolic diameter (LVEDd) [(60. 7 ± 9. 9)mm vs. (53. 5 ± 10. 8)mm, P=0.001], left ventricular end systolic diameter (LVESd) [(49.1 ±13.3)mm vs. (39.7 ±13.0)mm, P﹤0. 001], and the incidence of exacerbated left heart failure (20. 7% vs. 4. 8%, P = 0. 003), fatal arrhythmias (55. 2% vs. 21. 4%, P ﹤0. 001) and cardiac death (6. 9% vs. 0. 7%, P =0. 019) during hospitalization were significantly higher in the prolonged QRS group than in the normal QRS group. Left ventricular ejection fraction( LVEF) in the prolonged QRS group was significantly lower than in the normal QRS group (39. 6% ±17. 3% vs. 50. 5% ± 17. 3%, P =0. 002). Heart rates [(92. 4 ± 21. 4)bpm vs. (81. 6 ± 19. 9)bpm,P=0. 035], plasma BNP(7. 2 ± 0. 8 vs. 6. 7 ± 1. 0, P=0. 029), LVEDd(63. 5 ± 9. 1 vs. 57. 9 ± 9. 1, P=0. 015), LVESd (52. 9 ± 12. 2 vs. 44. 3 ± 11. 8, P=0. 005), incidences of left heart failure deterioration (18. 2% vs. 3. 2%, P=0. 018), fatal arrhythmias (63. 6% vs. 36. 5%, P=0. 027) and cardiac death ( 9. 1% vs. 0%, P=0. 015 ) during hospitalization among male patients in the prolonged QRS group were significantly higher than those in the normal QRS group, but LVEF ( 35. 0% ± 15. 3%vs. 47. 1% ± 16. 2%, P =0. 003 ) was on the opposite. The incidence of left heart failure deterioration among female patients in the prolonged QRS group was higher than that in the normal QRS group ( 28. 6%vs. 6. 1%, P=0. 034). QRS complex duration was positively related to LVEDd ( r=0. 4019, P﹤0. 001) and LVESd ( r =0. 3289, P ﹤0. 001 ) . LVEF in male patients was significantly lower than in female patients (40. 0% ± 16. 7% vs. 53. 2% ± 17. 6%, P﹤0. 001). On the contrary, LVEDd [(59. 4 ± 9. 4) mmvs. (50.3±10.6)mm,P﹤0.001],LVESd[(46.6±12.5)mmvs. (36.2±12.4)mm,P﹤0.001] were greater in male patients than in female patients. After adjusting for gender , age, cigarette smoking, history of high blood pressure, serum creatinine, low-density lipoprotein cholesterol, LVEF, LVEDd, LVESd, use of angiotensin converting enzyme inhibitors ( ACEI) or angiotensin receptor blockers ( ARB) and aldosterone receptor blockers, multiple logistic regression analysis showed that prolonged QRS complex duration is an independent risk factor of adverse prognosis for the patients with HF during hospitalization (OR=4. 21,95%CI:1. 59-11. 12,P=0. 004), and female gender is a protective factor for them ( OR=0. 304,95%CI:0. 116-0. 793,P=0. 015). Conc1usions The incidences of left heart failure deterioration, fatal arrhythmias and cardiac death in the chronic left heart failure patients with prolonged QRS duration were higher than in those with normal duration. Female gender is a protective factor for chronic left heart failure.

ST segment depression fQRS may be a new predictor of mortality of non-ST elevation myocardial infarction / 重庆医学

Objective To observe the incidence of fragmented QRS complex (fQRS)and ST Segment depression fQRS (STD fQRS)during the first 48 hours after non-ST elevation myocardial infarction(NSTE MI)and discuss the value of predicting mortality in patients with NSTE MI .Methods Based on the ECGs ,the patients with NSTE MI were divided into two groups :fQRS and non fQRS group .And then fQRS group was divided into two sub-groups :STD fQRS and non-STD fQRS group .Their mortality was studied during long-term follow-up .Results (1)731 patients with NSTE ACS [the NSTE MI group(n=609) and the UA group(n=122)] were studied .The incidence of fQRS in the NSTE MI group was higher than that of the UA group .(2)All cause mortality in the fQRS group were higher than that in the non-fQRS group ,and all-cause mortality in the STD fQRS group were higher than that in the non-STD fQRS group ,all the above results were not only in the early stages of NSTE MI ,but also in the long term fol-low-up .(3) Multivariate Cox regression analysis revealed that STD fQRS was an independent significant predictor for all cause mortality ,but not of the fQRS .Conclusion The STD fQRS may be an independent predictor of mortality in patients with NSTE MI .

Effect of Shenfu Injection on QRS Complex in Patients with Chronic Heart Failure / 医药导报

Objective To investigate the relationship among electrocardiogram QRS complex duration,left ventricular ejection fraction( LVEF),N-terminal pro-brain natriuretic peptide( NT-proBNP)and their relation to New York Heart Association (NYHA)functional classification in patients with chronic heart failure(CHF),and observe the intervention effects of Shenfu injection(SFI)on patients with CHF. Methods A total of 72 CHF patients were randomly assigned to treatment group(36 cases)and control group(36 cases). Patients in the control group received standard care,and those in the treatment group received standard care plus 1. 0 mL·kg-1 ·d-1 of SFI in 5% glucose for two weeks. Before and after the treatments,the electrocardiogram QRS complex duration,LVEF,NT-proBNP were measured and NYHA functional classification was evaluated. Results Electrocardiogram QRS complex duration was negatively correlated with LVEF and was positively correlated with NT-proBNP and NYHA functional classification( P〈0. 05 ). After the treatment,the proportion of patients with NYHA classⅠ-Ⅱsignificantly increased and classⅢ-Ⅳsignificantly decreased in both groups. The treatment group was superior to the control group in reinstating cardiac function( P〈0. 05 ). After the treatment,electrocardiogram QRS complex duration and the levels of NT-proBNP were significantly descended and LVEF were significantly ascended in both groups(P〈0. 05). The level of NT-proBNP in the treatment group was significantly lower than in the control group(P〈0. 05),but electrocardiogram QRS complex duration and LVEF did not show significant difference. The prior-and post-treatment difference in electrocardiogram QRS complex duration and LVEF was more obvious in the treatment group than in the control(P〈0. 05). Conclusion The extension of electrocardiogram QRS complex duration is correlated with plasma NT-proBNP elevation and cardiac dysfunction,which can be used as a reference for disease progression or medication efficacy. SFI is effective on CHF of the yang-qi deficiency type.

Analysis of esoPhageal electro Physiological examination of 12 wide QRS comPlex with tachycardia / 中国综合临床

Objective To identify the charactor of wide QRS complex tachycardia( WCT)throuGh transesophaGeal atrial pacinG( TEAP ). Methods TEAP and intracadiac electrophysioloGical examination infoamation of l2 cases WCT were collected and analyzed from January to February in 20l2 of Wuhan Asia Heart Hospital. Results Comparison of TEAP and intracadiac electrophysioloGical examination showed that l0 in l2 patients were match. Conclusion TEAP is a rapid and convenient method to diaGnose most WCT.

Eletrocardiografia computadorizada em cães: estudo comparativo / Computerized electrocardiography in dogs: a comparative study

Computerized electrocardiography (C-EKG) has been more frequently used in Veterinary Medicine. Many equipment models are available for this purpose. Due to possible device sensitivity and reproducibility differences during examination, the main goal of this study was to compare electrocardiographic parameters of dogs using two different C-EKG systems: Wincardio Micromed® (WIN) and TEB ECGPC® (TEB). Forty two healthy male and female dogs of different breeds (Cocker Spaniel, Dachshund, Labrador, Pinscher, Pitbull Terrier, Poodle, Schnauzer, Shih Tzu, Yorkshire and mongrel dogs), with age between 4 months and 16 years old were grouped according to weight and evaluated by both systems. The electrocardiographic measurements were performed on DII lead for both systems. The study showed that the TEB system was more sensitive for measurement of P wave and QRS complex duration, while the WIN system showed more sensitivity for the measurements of amplitude of the same parameters. The larger animals (26-37kg) showed greater variance in the measurements of P wave and QRS complex amplitude and duration than the groups of medium (14-25kg) or smaller (3-13kg) dogs. These differences must be considered when using diverse computerized electrocardiography systems to perform measurements due to the possibility of erratic interpretation of the results between veterinary medicine services.

O método de eletrocardiografia computadorizada (ECG-C) vem sendo crescentemente difundido na medicina veterinária, havendo atualmente diversas marcas e modelos de eletrocardiógrafos disponíveis no mercado. Diante da possibilidade de diferenças na sensibilidade e na reprodutibilidade das medidas obtidas nos traçados, o presente estudo teve como objetivo comparar os parâmetros eletrocardiográficos de cães, obtidos por dois sistemas. Foram avaliados dois diferentes softwares computadorizados, o Wincardio Micromed® (WIN) e o modelo TEB ECGPC® (TEB). Quarenta e dois cães hígidos, de diferentes raças (Cocker Spaniel, Daschund, Labrador, Pinscher, Pit Bull Terrier Poodle, Schnauzer, Shit Tzu, Yorkshire e sem raça definida), machos e fêmeas e com idade entre 4 meses e 16 anos foram agrupados segundo o peso e examinados pelos dois sistemas. As medidas eletrocardiográficas dos diferentes traçados foram analisadas na derivação DII. Os resultados indicaram que o sistema TEB apresentou maior sensibilidade na obtenção das medidas de duração da onda P e do complexo QRS, enquanto o sistema WIN foi mais sensível para determinar as medidas de amplitude dos mesmos parâmetros. Os animais de maior porte (26-37kg) apresentaram maior variância nas medidas de duração e amplitude de onda P e duração do complexo QRS em comparação aos cães de médio (14-25kg) e pequeno (1-13kg) porte. O achado de diferenças entre os sistemas testados deve ser levado em consideração ao se empregar os diversos equipamentos para diagnóstico por meio de ECG-C na rotina clínica, de modo a evitarem-se divergências na interpretação dos exames entre diferentes prestadores de serviços veterinários.

Effects of grade of ischemia on arrhythmia in patients with acute myocardial infarction / 中华急诊医学杂志

Objective To evaluate clinical significance of the grade of ischemia by QRS complex on the admission electrocardiogram(ECG)to predict severe arrithmia in patients with acute ST-segment elevation myocardial infarction(STEMI).Methods Patients with acute ST-segment elevation myocardial infarction(STEMI)admitted to emergency department from July 2003 to April 2008 were enrolled.A total of 223 patients met the criteria(ischemic chest pain ≥ 30 min,2 or more adjacent leads of ST segment elevation and onset time within 12 h).Exclusion criteria were bundle branch block and left ventricular hypertrophy.All enrolled patients were divided into two groups based on the enrollment electrocardiogram:grade 2 ischemia(ST elevation without terminal QRS distortion; n =134)and grade 3 ischemia(ST elevation with terminal QRS distortion; n =89).Patients of the two groups had comparable genderproportion,average age and coronary heart disease risk factors etc.All patients received thrombolytic therapy.The incidence rate of ST segment resolution(STR)and severe arrithmia in hospital stay were observed.Numerical variables were expressed mean ± standard deviation and compared by unpaired Student't test,Categorical variables were expressed percentage and compared by chi square test.Multiple logistic regression analysis was used to determine independent predictors of severe arrithmia.Results Patients with grade 3 ischemia had greater Σ ST on admission and 2 h after thrombolysis ECGs(P ＜ 0.01),the incidence rate of STR in patients with grade 3 ischemia was lower than that in patients with grade 2 ischemia(P ＜0.01).The peak creatine kinase MB fraction was higher in patients with grade 3 ischemia than that in patients with grade 2 ischemia(P ＜ 0.01).There was no significant difference of the incidence of severe arrithmia,such as ventricular premature beat,ventricular tachycardia or fibrillation,second-degree or third-degree atrioventricular block,and sinus arrest between the two groups(P ＞ 0.05),but there was a trend of higher incidence of severe arrithmia in patients with grade 3 ischemia compared with that in patients with grade 2 ischemia.Multiple logistic regression analysis demonstrated that the independent predictors of severe arrithmia were duration from symptom to thrombolysis and initial.Σ ST,whereas grade 3 ischemia remained a strong predictor of severe arrithmia.Conclusions Grade 3 ischemia on admission is associated with lower incidence of STR in patients with ST-segment elevation myocardial infarction(STEMI)after thrombolysis and a strong predictor of severe arrithmia.

Unveiling the uncertainty principle in the QRS complex offset detection on high resolution electrocardiography

The accuracy of high resolution electrocardiographic (HRECG) methods for stratifying the risk of malignant ventricular arrhythmia depends on the fidelity of QRS fiducial points detection. This study aims at examining the effect of acquisition and processing variables in HRECG on the variability of QRS complex offset (QRS offset) detection in simulated and biological signals, as well as investigating the factors related to the so called uncertainty principle applied to HRECG. Successive QRS offset locations were calculated in different signals configurations including HRECG data from patients with and without ventricular late potentials and simulated data using linear and exponential functions. The expected error in QRS offset detection was assessed as a function of: i)   signal characteristics (Simulated or Biological); ii) Sampling Frequency (SF); iii) Residual Noise Level (RNL); iv) QRS maximum amplitudes. The uncertainty principle was related to HRECG and a given exponential signals, and increasing RNL up to  0.5  μV. SF and RNL are outstanding factors influencing QRS offset variability. Thus, HRECG related uncertainty principle is a deterministic phenomenon associated with both HRECG signal and mathematical formulation of the terminal decay of the QRS complex to the fusion with the ST segment.

A precisão dos resultados dos exames de eletrocardiografia de alta resolução (ECGAR) para estratificação do desenvolvimento de arritmias ventriculares malignas depende da fidelidade na detecção dos pontos fiduciais do complexo QRS. O presente estudo tem o objetivo de avaliar o efeito das variáveis de aquisição e processamento do ECGAR sobre a variabilidade da detecção do ponto final do complexo QRS (QRS-fim) em sinais biológicos simulados e reais, bem como investigar o efeito de condições relacionadas ao assim formulado “princípio da incerteza da eletrocardiografia de alta resolução”. Detecções sucessivas do QRS-fim foram realizadas usando diferentes configurações de sinais simulados e de pacientes com e sem potenciais tardios ventriculares. Os sinais simulados empregaram funções lineares e exponenciais para mimetização da porção final do complexo QRS. O erro de detecção do QRS-fim esperado foi avaliado em função de: i) procedência dos sinais (simulado ou biológico); ii) frequência de amostragem (FA); iii) nível de ruído residual (NRR); iv) amplitude máxima do complexo QRS. A presença do princípio da incerteza relacionou-se ao padrão de decaimento exponencial e ao aumento progressivo da NRR, até  0,5  μV. FA e NRR têm impacto significativo na variabilidade do QRS-fim. Assim, o principio da incerteza da ECGAR é um fenômeno determinístico dependente da forma de onda relativa ao decaimento da região terminal do complexo QRS até a sua fusão com o segmento ST.

Myocardial ischemia analysis based on electrocardiogram QRS complex in time domain / 国际生物医学工程杂志

Objective ST-T complex change, which represents the ventricle repolarization phase, is the main clinical indicator in detecting myocardial ischemia (MI) based on electrocardiogram (ECG) signals.However, its feature point location is not accurate due to interferences. In this paper, a new approach about myocardial ischemia analysis was proposed based on QRS complex. Methods QRS complex, representing the ventricle depolarization process, was used to analyze myocardial ischemia, and some parameters were extracted synthetically in time domain. Then they were used for statistical analysis of myocardial ischemia states and non-myocardial ischemia states. Results Five parameters had significant differences after verification of Non-MI signals in MIT-BIH database and MI signals in long-term ST database (LTST) and they were: QRS upward and downward slopes, transient heart rate, R angle and Q angle in a triangle QRS. Conclusion Five parameters extracted from QRS complex had significant differences. The proposed method provides an important basis for myocardial ischemia detection.