Significant prolongation of QT interval would easily cause malignant arrhythmias, and therefore in the research and development of new drugs, great importance should be attached to the evaluation of QT interval prolongation. As a necessary guiding principle for new drug research and development, ICH-E14 Guidelines, in the form of industry norms, stipulates that new non-antiarrhythmic drugs must be evaluated for QT/QTc interval prolongation before marketing. It means that electrocardiogram (ECG) monitoring will play an important role in the safety evaluation of this kind of drugs. In order to complete the collection and comprehensive analysis of ECG data with high standards and quality, this paper focuses on the methodology of QT/QTc interval measurement from several aspects. It introduces the requirements for instruments and personnel during QT interval measurement, the selection of measurement leads, the determination of QT interval starting and end points,  QT interval measurement under different circumstances，different correction methods for QT intervals, and notes during data measurement.

Heart rate variability (HRV) is a non-invasive index for assessing the autonomic nervous system’s regulation of cardiac rhythm. This index reflects the automaticity of the heart and information related to physiological states. HRV has been used to evaluate the cardiac health, predict the risk of cardiovascular events, and monitor the efficacy of diseases. In recent years, related studies have found that HRV also has important values in evaluating non-cardiovascular system diseases, as well as mental stress and stress responses. This article reviews the history, recent advances in research and application of HRV, aiming to provide more information for clinical physicians.

The National Medical Products Administration demands that the relevant requirements for  drug clinical studies initiated since July 31, 2023 follow the “E14: the clinical evaluation of QT/QTc interval prolongation and proarrhythmic potential for non-antiarrhythmic drugs”. This paper introduces QT interval and QTc, non-antiarrhythmic drugs potentially leading to QT interval prolongation and even torsade de pointes, the mechanism of QT interval prolongation, predisposing factors, and other related issues. It is aimed to arouse more attention to the effects of new nonantiarrhythmic drugs on QT/QTc interval among clinicians, and to improve the safety of drug use.

Atrial fibrillation (AF) is one of the most common arrhythmias. It is characterized by concealment, paroxysmal nature, complexity, and high mortality and disability rate; the prevalence rate of AF is on the rise. The new emergence of artificial intelligence technology breaks through the limitations of traditional methods of AF screening, showing unique advantages and broad application prospects in the screening, diagnosis and prediction of AF. Intelligent wearable devices have higher feasibility, specificity and sensitivity in the screening  of AF, with high cost-effectiveness in clinical application.

The prevalence rate of cardiovascular diseases in China has been increasing, therefore the precise diagnosis and treatment of arrhythmias is particularly critical. ECG examination is the main basis for the diagnosis of arrhythmias. At present, artificial intelligence ECG analysis technology has brought new possibilities to improve the efficiency and accuracy of clinical diagnosis and treatment of arrhythmias. This paper reviews the latest progress in the application of artificial intelligence ECG analysis technology at home and abroad, and summarizes the prospects and challenges of the technology in the diagnosis of arrhythmias.

Leadless pacemakers (LPMs), which have emerged in recent years, avoid the lead and pocketrelated complications associated with conventional lead pacemakers, such as tricuspid regurgitation, lead fracture, lead endocarditis or pocket infection. Not only has LPM a significant advantage over conventional pacemakers in terms of safety, but also its stability of pacingrelated parameters has been demonstrated during a relatively long followup period.  At present, LPM has been approved for marketing in China. Although the application of LPM is still in its infancy, the implantation volume is growing rapidly, therefore its development prospect in the future is good. This article reviews  the clinical application evidences of existing LPM, related techniques and postoperative management of LPM implantation, future development direction of LPM, and so on.

The etiology of sudden unexplained death (SUD) is complicated, and its  incidence remains significant at present. The key to its prevention and treatment lies in identifying the underlying pathogenic factors. With the progress of molecular biology techniques, numerous  studies at home and abroad have substantiated a strong association between sudden cardiac death (SCD) caused by pathogenic gene mutations and SUD. The conspicuous clustering characteristics observed in cases of Yunnan sudden unexplained death (YNSUD) indicate the potential involvement of molecular genetics. In the population of the affected area, the detection rates of abnormal electrocardiogram (ECG) indicators increased while cardiac pathological changes were found in 90% of sudden death cases, which further implies a possible correlation between YNSUD and pathogenic gene mutations related to SCD. Understanding the genetic predisposition, genetic mutation, risk factors, and pathogenic mechanisms of SCD contributes to identifying the highrisk factors associated with this kind of sudden death, so as to carry out targeted prevention and treatment. This paper reviews the current research trends in hereditary arrhythmias and hereditary cardiomyopathy related to SUD, and summarizes the latest research results and pathogenic factors.It is aimed to provide a foundation for further investigations on the etiology.

Heart rate variability (HRV) is a noninvasive index for evaluating cardiac autonomic function, which is closely related to many diseases. It could be used for disease screening, risk stratification, diagnosis and treatment, efficacy evaluation and so on. With the development of technology and optimization of algorithms, the application of HRV in pacemakers and wearable devices has developed  further. This paper mainly illustrates the research background, progress in clinical application and research trends of HRV, and looks forward to the  research directions in the future.

Atrial fibrillation (AF) has become an important disease that endangers the health of middle-aged and elderly people in China, and it is related to the risk of stroke and death. At present, pathophysiological mechanisms such as atrial structural remodeling, electrical remodeling, inflammation, autonomic nervous system disorders, and non-coding RNA may explain the occurrence and development of AF. The treatment of AF mainly includes anticoagulation, conversion of sinus rhythm, and control of ventricular rate. In addition, antiinflammatory, autonomic nerve intervention and genomics intervention therapy may become  new types of therapies for AF. This article reviews the research progress in the   pathogenesis and treatment of AF.

Brugada wave is a special ECG pattern that presents as a “triad” of right bundle branch block, STsegment elevation in the right chest lead, and T wave inversion. It could lead to arrhythmia and sudden cardiac death. It has been previously considered that Brugada wave is associated with genetics, electrophysiological mechanism, nerve crest hypothesis and so on. The latest studies have found that mutations in mitochondrial DNA and tRNA, inflammation, and myocardial stroma abnormalities may also be involved in the occurrence and development of Brugada wave. This paper mainly reviews the latest research progress of the electrocardiographic mechanism of Brugada wave.

Objective  To investigate the importance of standard operation of ECG examination for quality control of remote ECG network. Methods  We analyzed ECGs transmitted through the network from January 1,2022 to June 30,2023 at the ECG Network Center of the First People’s Hospital of Xianyang. During the time period, we took every six months as a stage, and performed targeted operation training of ECG examination at each stage. We compared the graphic quality problems and the number of ECGs with quality problems among different stages. Results  After regular ECG operation training for clinical medical staff and instrument maintenance, the quality of ECG graphics has been greatly improved. Conclusion  Standard operation of remote ECG network directly affects the diagnostic accuracy of ECGs. Regular standardized training of ECG operation for clinical medical staff could improve the accuracy of ECG examination results, and avoid the occurrence of medical adverse events.

Atrial fibrillation (AF) is the most common arrhythmia and may easily lead to various complications. Therefore, precision medical methods are needed to identify and enhance AF detection to achieve early diagnosis and treatment. Artificial intelligencebased wearable devices are of great value for the screening and management of AF patients. This article reviews the relevant literature on recent applications of such devices for AF screening.

In recent years, the combination of remote ECG monitoring and artificial intelligence (AI) technology has greatly assisted the diagnosis and treatment of cardiovascular diseases, and shows extremely broad development prospect. This paper summarizes the progress in the application of AIbased remote ECG monitoring technology in the intelligent diagnosis, hierarchical diagnosis and treatment, prognosis evaluation, and individualized management of acute coronary syndrome. It also introduces the active health intelligent management system of the heart which has been constructed and gradually improved in China on this basis.

Handheld ECG collector is a simple bipolar singlelead ECG recording device. A standard Ⅰlead ECG can be conveniently recorded just by pressing the positive and negative electrodes with both thumbs. It is mainly utilized in the monitoring of arrhythmias. As a household medical equipment, it is quite popular with the majority of middleaged and elderly friends. Based on the nature of unipolar  and bipolar leads, and their intrinsic connection, this paper derives a recording method of standard leads and augmented unipolar leads. Meanwhile, on the basis of further exploring the internal connection between CR lead and Wilson lead, the method of directly recording CR chest lead ECGs by handheld ECG collector is creatively proposed. Both theory and practice show that the equivalent recording method of augmented unipolar limb lead and the bipolar recording method of CR chest lead can not only meet the clinical needs, but also prove to be unique. This method can fully develop the medical value of household medical devices, which is worthy of be promoted and popularized.

Various reasons may lead to inappropriate shocks of entirely subcutaneous implantable cardioverter defibrillator as the detected frequencies reach the shock zone. These reasons include the oversensing of intracardiac signals (such as  T, P, F, f, or U waves),  multiple counting of QRS complexes, rapid supraventricular tachycardia, myopotential interference, air entrapment, failure of electrode lead or pulse generator, cardiopulmonary resuscitation, in vitro electromagnetic interference, and SenseBnoise. It is recommended to  readjust its parameters by programmable controlling, and  actively treat primary diseases. It is required to adjust the electrode lead and pulse generator, or implant a transvenous implantable cardioverter defibrillator instead if necessary.

Objective To assess the accuracy of wearable electrocardiogram ( ECG) monitoring device for detecting arrhythmias ( sinus rhythm, premature ventricular contraction premature atrial contraction, and atrial fibrillation), and heart rate in a clinical. Methods A total of 321 volunteers (875 ECG records) participated in this study, including 146 males ( 531 ECG records) and 175 females ( 344 ECG records). A wearable ECG monitoring device was employed to record ECGs for detecting arrhythmias and heart rate. The detection results were compared with physicians clinical diagnostic results based on 12-lead ECG machine (regraded as the gold standard for diagnosing arrhythmias and detecting heart rate). Accuracy and consistency evaluation of the two detection methods was conducted in all the subjects, including accuracy, sensitivity, specificity, F1 score, area under curve (AUC) of the receiver operating characteristic curve, Bland-Altman consistency analysis, mean absolute error, and correlogram. Results Regarding arrhythmia identification, wearable ECG monitoring device exhibits impressive performance metrics, with an AUC of 0. 98, accuracy of 0. 98, sensitivity of 0. 96, specificity of 0. 99, and an F1 score of 0. 96. In terms of heart rate monitoring, a robust correlation between the wearable ECG monitoring equipment and the ECG machine is evident, with a substantial total correlation coefficient of 0. 84 (P< 0. 01). Bland-Altman consistency analysis reveals that the two methods display a mean difference of - 0. 97 times per minute, a mean standard deviation of 8. 02 times per minute, and a 95% confidence interval ranging from -16. 69 to 14. 75 within an acceptable level. Conclusion Wearable ECG monitoring device can accurately detect arrhythmias and heart rate.

Objective  To explore the effect of different correction methods of QT interval in patients with atrial fibrillation (AF) separately at AF and  sinus rhythms. Methods  The ECGs of AF patients both with AF and sinus rhythms were selected from the public information platform ECG-ViEW database. The correction effect of Bazett, Fridericia, Framingham and Hodges formulas is compared and analyzed for the same patient separately at AF and sinus rhythms.  The linear relationship between QTc corrected by different formulas and heart rate or the measured value of QT interval was analyzed. ResultsThere is a statistically significant difference in the QT interval among AF patients during AF and sinus rhythme[(374.57±67.73) ms vs. (396.71±55.68) ms, P<0.01]. The QTc corrected by Hodges formula does not vary significantly between the two rhythms. Its  slope of the regression line to the heart rate is very small, and the QTc corrected by Hodges formula shows a good linear relationship with the measured value of QT interval. The QTc corrected by  commonly used Bazett formula in clinical practice shows a positive linear relationship with the measured value of QT interval. Conclusion  Commonly used Bazett, Fridericia and Framingham formulas lead to poor performances in correcting QT interval of ECGs during AF rhythm. The effect of Hodges formula on correcting QT interval is close separately at AF and sinus rhythms, which could greatly reduce the influence of heart rate on QT interval.  Hodges formula is universal in the population, and makes a good clinical indicator for monitoring the prolongation of QT interval in AF patients.

Objective  To compare the effectiveness and safety of secondgeneration cryoballoon ablation and conventional drug therapy separately as the initial treatment for patients with paroxysmal atrial fibrillation (AF). Methods  We selected 44 patients with paroxysmal AF who had been initially treated by secondgeneration cryoballoon ablation as the ablation group. The operation time, ablation time, X-ray fluoroscopy time, pulmonary vein isolation rate, and surgical complications were observed. We selected another 44 inpatients with paroxysmal AF who had been initially treated by drug therapy during the same period as the medication group. The two groups were followed up separately one month, and 3, 6 and 12 months after discharge to observe the recurrence rate and complications of AF. The efficacy and safety of treatment were further compared between the two groups. Results  The operation time, ablation time and X-ray fluoroscopy time of the ablation group were (108.0±39.0) minutes, (35.0±11.7) minutes and (10.0±6.9) minutes, respectively; the immediate isolation rate of pulmonary vein was 100%; there were 3 cases (6.8%) of operationrelated complications, including one case of vagus reflex and 2 cases of transient phrenic nerve injury. In the medication group, drug-induced sinus bradycardia occurred in 2 cases, QTc was prolonged in one case, and thyroid function was decreased in one case. After a mean follow-up of (12.0±5.) months, the recurrence rate of AF was 11.4% in the ablation group while the rate was 20.5% in the medication group. The recurrence rate in the ablation group was significantly lower than that in the medication group (P=0.033). The incidence of complications or adverse reactions did not vary significantly from the ablation group to the medication group (6.8% vs 9.1%, P=0.108). Conclusion  Compared with drug therapy, the secondgeneration cryoballoon ablation has a higher success rate for paroxysmal AF without increased risk of complications. The secondgeneration cryoballoon ablation can be considered as one of the initial treatment strategies for paroxysmal AF.

患者女，63岁，因心前区不适，行24 h动态心电图检查。24 h时间散点图呈多层分布；Lorenz-RR散点图呈四分布，还可见与夺获相关的两个点集，逆向心电图显示为窦房阻滞,交界性逸搏及自主节律合并逸搏窦性夺获。本病例二度窦房阻滞的散点图特征明显，Lorenz-RR散点图与差值散点图相结合，是快速、准确地分析这类复杂心律失常的重要手段，夺获点集在鉴别二度窦房或房室阻滞中有重要作用。

Objective  To evaluate the efficacy and safety of the domestic Columbus 2.0 three-dimension (3D) cardiac electrophysiological mapping system and its supporting catheter in the treatment of tachyarrhythmias through a prospective, multicenter and singlearm study. Methods  We selected 50 consecutive patients with tachyarrhythmias from 4 electrophysiological centers of Shanghai;  20 patients (40.0%) are males, the mean age of patients is (55.38±18.14) years old. Radiofrequency ablation was performed on these patients guided by Columbus 2.0 system and its supporting catheter. The immediate success rate, operation time, X-ray exposure time and dose, and adverse events were recorded. All the patients were followed up for 6 months. Results  There are 34 patients with atrioventricular nodal reentry tachycardia, 11 cases with atrioventricular reentry tachycardia, one with atrial tachycardia, one with typical  atrial flutter, and 3 patients with premature ventricular ntraction.  The immediate success rate of the procedure is 100%; no catheter ablation related adverse event occurs during the perioperative period. The average operation time is 114.00 (89.75, 166.25) min, the  average X-ray exposure time is 5.90 (3.78, 8.07) min, and the  average X-ray exposure dose is 23.96 (8.00, 50.00) mGy. There is no recurrence during 6 months of follow-up.  Conclusion  The efficacy and safety of Columbus  2.0 3D cardiac electrophysiological mapping system and its supporting catheter is satisfying in treating tachyarrhythmias, especially supraventricular arrhythmias.

Unlike other types of heart failure (HF), the efficacy of traditional medication and therapies are usually not reliable in  patients with HF with preserved ejection fraction (HFpEF). It may be attributed to obviously heterogeneous etiologies and inconsistent pathophysiological pathways among such patients. GE's phenotyping is a novel etiology oriented classification method. It not only facilitates grouping HFpEF patients with similar pathophysiological mechanisms, but also contributes to making appropriate diagnosis and treatment plans, and taking prognosis assessment and management measures for different types of HF patients. In the future, GE's phenotyping is expected to be an important reference for clinical study design for these patients.

More and more patients with renal artery stenosis (RAS) have been found in the clinical practice of cardiovascular disease. RAS is an important cause of hypertension and(or) renal insufficiency, and its main cause is atherosclerosis. In China, with aging of population, among the patients with coronary artery disease and peripheral vascular disease, those with atherosclerotic renal artery stenosis (ARAS) have been  constantly increasing. ARAS is one of the important causes of secondary hypertension. If ARAS patients can be found in an early phase, and made correction, diagnosis, treatment and effective intervention, it will be of positive significance for them to control blood pressure and improve the quality of life. This review focuses on the epidemiology for ARAS, the relationship between ARAS and hypertension, the diagnostic clues for ARAS, and its examination methods and treatment.

Objective  To investigate the changes of serum creatine kinase isoenzyme (CK-MB), homocysteine (Hcy) and B-type natriuretic peptide (BNP) levels in patients with acute myocardial infarction (AMI), and to analyze their correlation with the severity of the disease and their predictive value on major adverse cardiovascular events (MACEs). Methods   A total of 102 patients with AMI were selected as the research group while another 102 healthy physical examinees during the same period were selected as the control group. The changes of serum CK-MB, Hcy and BNP levels were compared separately between different groups and among the enrolled patients with different numbers of coronary lesions. Spearman and Pearson correlation analysis was utilized to explore the correlation between serum indicators and the number of coronary lesions or Gensini score. Patients in the research group were treated by percutaneous coronary intervention (PCI). They were divided into subgroups with or without MACEs according to the presence or absence of MACEs 6 months after the surgery. The serum CK-MB, Hcy and BNP levels were analyzed in each group before PCI and one month after the surgery. The predictive value of each serum indicator level one month after operation on MACEs was analyzed by using ROC curve. ResultsThe serum levels of CK-MB, Hcy and BNP in the research group were higher than those in the control group (P<0.01); serum CK-MB, Hcy and BNP levels were positively correlated with the number of coronary lesions and Gensini score (P<0.05). One month after surgery, the serum CK-MB, Hcy and BNP levels of the patients with MACEs were higher than those of the patients without MACEs (P<0.05). The AUC value of the combination of serum CK-MB, Hcy and BNP levels one month after surgery for MACEs was 0.943, which was higher than the AUC value of single indicator (0.769, 0.847 and 0.794, respectively;P<0.05). Conclusion  The serum levels of CK-MB, Hcy and BNP in AMI patients are elevated, which are closely related to the severity of the disease. The combined detection of the above serum indicators has certain predictive value for the occurrence of MACEs.

Atrial fibrillation (AF) is one of the most common arrhythmias with high disability rate and mortality, which seriously affects the quality of patients  life. Thromboembolism is one of the most serious complications of AF, however, the mechanism of thromboembolism caused by AF has not been fully clarified at present. Some biomarkers and risk scores could be applied in predicting the occurrence and development of AF related thromboembolism. This paper reviews the research progress in risk factors of thromboembolism among patients with AF in terms of  patients  basic data, laboratory examinations, echocardiography, etc.

Many commonly used medications have the potential to induce QT interval or QTc prolongation, subsequently leading to torsade de pointes (TdP) and other arhythmias, which may further deteriorate into ventricular fibrillation and even sudden cardiac death. Therefore, it is crucial to  make identification, early warning and correction of risk factors in order to prevent and reduce the risk of druginduced QT interval prolongation and TdP. In recent years, clinical decision support systems and other early warning strategies have been widely employed for predicting QT interval or QTc prolongation by identifying various risk factors, and  warning to the highrisk population susceptible to TdP. This article summarizes drugs and related risk factors that contribute to prolonged QT interval and TdP risk, as well as concludes the existing warning measures, aiming to offer guidance for managing patients exposed to the related risks.

心肌缺血后心电图束支阻滞的改善并不多见。本文报告1例完全性右束支阻滞患者在心肌缺血发生后出现QRS波正常化，分析其原因是缺血导致对侧束支新发传导阻滞，使传导出现伪改善。临床医师对这类患者应提高警惕，及时鉴别并进行必要的干预，这对患者的治疗和预后具有重要意义。

At present, many studies have shown that QRS complex duration is not completely linear with ventricular mechanical asynchrony, however, synchronous ventricular electrical activation is an important prerequisite for normal systole and diastolic functions of the ventricle. Patients with chronic heart failure (HF) often have ventricular systolic dysfunction. Although in the early stages of HF, the heart makes adaptive changes, once the compensatory limit is exceeded, it can lead to heart remodeling and serious damage to heart functions. Electrocardiography and mechanical remodeling is influenced by multiple factors such as cardiac structure, and cellular and molecular levels, which is manifested by prolonged QRS complex duration in the ECG. In the treatment of HF, in addition to traditional pacemakers, the emerged conduction system pacing in recent years is more suitable to the characteristics of physiological conduction, not only significantly shortening the QRS complex duration but also significantly improving ventricular mechanical synchronization. This review summarizes the possible mechanisms of electricalmechanical asynchrony in patients with chronic HF, and its relationship with QRS complex duration. It also covers the influence of the two factors on cardiac function.

Objective  To investigate the influence of different exercise and rest habits on hemodynamics of young patients with chest tightness. Methods  We selected 100 outpatients under 40 years old with chief complaints of chest tightness and other discomforts. They all denied basic medical history, and were generally normal in preliminary screening of ECG, chest X-ray, ultrasound cardiogram and myocardial enzymes indexes. According to  exercise and rest habits, they were divided into regular exercise and rest group (18 cases), less exercise or stay up late group (35 cases), and  less exercise plus stay up late group (47 cases). The changes of hemodynamic monitoring indexes of each group were analyzed. According to clinic blood pressure, the enrolled patients were divided into normal blood pressure group (57 cases) and elevated blood pressure group (43 cases). The changes of body mass index (BMI) and hemodynamic monitoring indexes were comparatively analyzed between the two groups. Results Among these groups with different exercise and rest habits, BMI, cardiac index(CI), systemic vascular resistance index (SVRi), and early diastolic filling ratio (EDFR) show statistical differences of medium equivalence between the groups.  There are statistical differences of high equivalence in BMI and left cardiac work index (LCWi) between the normal blood pressure group and the elevated blood pressure group while SVRi is statistically different between groups with medium equivalence. Compared with the normal blood pressure group, increased BMI and hemodynamic abnormalities are more common in the elevated blood pressure group (P<0.01); the hemodynamic abnormalities are more prone to present as high LCWi (P<0.01), high SVRi(P=0.01), and possibly high CI (P<0.05) and high EDFR (P<0.05). Conclusion  Among the population with unhealthy exercise and rest habits, the incidence of obesity and hemodynamic abnormalities are higher than those with exercise habits and regular schedule. The hemodynamic abnormalities are mainly manifested by the blood flow circulation state with relatively low discharge and high resistance, which indicates  increased preload. Unrecognized hypertension or hypertension without intervention are found in nearly half of the young patients with chief complaints of chest tightness.  The hemodynamic abnormalities are mainly manifested by the blood flow circulation state with relatively high  left ventricular stroke work, and normal or high systemic vascular resistance. In clinical practice, it should be paid more attention and given early intervention.