Initial clinical experience of left bundle branch pacing after transcatheter aortic valve implantation / 中华心血管病杂志

Objective: To investigate the efficacy and safety of left bundle branch pacing(LBBP) in patients after transcatheter aortic valve implantation (TAVI). Methods: This is a retrospective study. A total of 35 patients underwent TAVI and received pacemaker implantation from January 2018 to December 2020 in Beijing Fuwai Hospital were enrolled. Patients were divided into LBBP group (n=12) and right ventricular apex pacing (RVAP) group (n=23) according to the pacing position. The success rate of operation in LBBP group was calculated, and the occurrence of complications were observed, and the parameters of pacemaker were measured on the 3rd day and 1, 3 and 6 months after operation. The N-terminal pro-B-type natriuretic peptide (NT-proBNP), echocardiographic and ECG indexes were compared between the two groups on the 3rd day and 1, 3, and 6 months after pacemaker implantation. Result: A total of 35 patients were included, The age was (76.4±7.7) years, including 19 males (54.3%). The procedure time ((86.58±17.10)min vs. (68.74±9.18)min, P<0.001) and fluoroscopy duration ((20.08±4.44)min vs. (17.00±2.26)min, P<0.001) were significantly longer in LBBP group compared with RVAP group. The operation success rate of LBBP group was 11/12. There was no serious operation related complications such as pneumothorax, hemothorax, electrode dislocation, infection, and lower limb bleeding. The patients were followed up for 7.43 (5.21, 9.84) months. The programmed parameters of pacemaker were in the ideal range and stable during follow-up. At 3 and 6 months after operation, the left ventricular ejection fraction in LBBP group was higher than that in RVAP Group (at 3 months: (60.75±2.89)% vs. (57.35±3.33)%, P=0.004; at 6 months: (63.17±3.33)% vs. (56.17±3.97)%, P<0.001), NT-proBNP values was lower in LBBP group than that in RVAP Group (at 3 months: 822 (607, 1 150)ng/L vs. 1 052 (902, 1 536)ng/L, P=0.006; at 6 months: 440 (330,679)ng/L vs. 783 (588, 1 023)ng/L, P=0.001). At 1, 3 and 6 months after operation, the QRS duration was shorter in LBBP group than that in RVAP group (1 month: 99 (97, 107)ms vs. 126(124, 130)ms, P<0.001; 3 months: 98(96, 105)ms vs. 129(128, 133)ms, P<0.001; 6 months: 96(94, 104)ms vs. 130(128, 132)ms, P<0.001). Conclusions: For patients with permanent pacemaker indications after TAVI, LBBP is feasible, safe and reliable. It could improve the cardiac function in the short term, the long-term effect of LBBP needs to be further observed.

Clinical Characteristics, Etiological Distribution of Inpatients Presenting With Syncope: A Single-center Experience / 中国循环杂志

Objectives:To analyze the clinical characteristics, etiological distribution of inpatients with syncope in our center. Methods:Patients with syncope were consecutively enrolled from September 2014 to April 2017 in Center of Arrhythmia of Fuwai Hospital. Demographics, medical history, physical examination results and laboratory tests were collected according to screen algorism to investigate the possible etiologies of syncope. Risk stratification was performed based on guidelines for the diagnosis and management of syncope (version 2009,ESC)and Chinese expert consensus on the diagnosis and treatment of syncope (version 2014). Results:After collecting medical history, physical examination and performing laboratory tests, three hundred patients who experienced the latest syncope within 180 days before admission was identified from 5 191 patients, the average age was (57.7 ± 15.4) years, 177 (59.0%) were male, 235 (78.3%) experienced syncope within 30 days before admission, 9.7% patients had recurrent episodes, 80.7% were defined as high risk syncope patients, 144(48.0%)patients suffered structural heart disease. Cardiac syncope was the most common etiology (214 cases,71.3%), followed by reflex syncope(44 cases,14.7%) and orthostatic hypotension (8 cases,2.7%), while etiology was not identified in the rest 34 patients (11.3%). Among all the etiologies of syncope, brandy arrhythmia was the most common reason for syncope (37.3% [112 cases]). During onset of syncope prior to hospitalization, five patients were diagnosed with severe intracranial hematoma or cerebral hemorrhage, six cardiopulmonary resuscitations were performed, and eleven patients received external direct current cardioversion. Conclusions:Etiology could be defined in most of the syncope patients admitted to our center, the prevalence of high-risk syncope and syncope due to brady arrhythmias is high in this patient cohort, treatments of the syncope patients could be improved by etiological and timely prognosis.

Retrospective analysis on the clinical features and management of acute and subacute right ventricular perforation by pacemaker lead / 中华心血管病杂志

<p><b>OBJECTIVE</b>To describe the clinical characteristics and management of the acute and subacute cardiac perforation by pacing leads.</p><p><b>METHODS</b>We retrospectively analyzed clinical data of patients with acute and subacute right ventricular perforation by pacemaker lead occurred in our hospital between 2006 and 2011.</p><p><b>RESULTS</b>Seven cases of confirmed acute and subacute right ventricular perforation by pacemaker lead were enrolled. The perforation rate was 0.15%, 2 cases of perforation occurred during the procedure. The main manifestation was low blood pressure and pericardial effusion. These two patients with cardiac tamponade underwent urgent percutaneous pericardiocentesis and patients recovered without complication. The remaining 5 cases of perforation occurred within 4-16 days after the pacemaker implantation. The main symptoms were diaphragm stimulation and chest pain. Signs of leads dysfunction were observed in all 5 patients. The diagnosis of cardiac perforation was confirmed by chest X-ray, echocardiography, or computed tomography. In all these 5 patients, the leads were removed by simple traction under fluoroscopic guidance with surgical backup support, no complication was observed.</p><p><b>CONCLUSION</b>Acute and subacute right ventricular perforation is a rare but serious complication of pacemaker implantation. In most patients, the leads can be safely removed under fluoroscopic guidance with surgical backup support and close monitoring.</p>

Prevalence of atrial fibrillation in China and its risk factors / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the prevalence of atrial fibrillation (AF) and the relation with its risk factors in China.</p><p><b>METHODS</b>A total of 19 363 participants (8635 males and 10 728 females) aged ⋝35 years in geographically dispersed urban and rural regions of China were included in this cross-sectional survey. All participants received questionnaire, physical and blood examination. Echocardiography were performed for AF patients found in the survey.</p><p><b>RESULTS</b>Of the 19 363 participants, 199 were diagnosed with AF. The estimated age-standardized prevalence of AF was 0.78% in men and 0.76% in women. The prevalence of AF in participants aged <60 years was 0.41% in men and 0.43% in women, and was 1.83% in both men and women aged ⋝60 years. About 19.0% of males and 30.9% of females with AF were diagnosed with valve disease. Age- and sex-adjusted multivariable logistic regression analysis revealed that myocardial infarction, left ventricular hypertrophy (LVH), obesity, and alcohol consumption were associated with a increased risk of AF(P<0.05).</p><p><b>CONCLUSION</b>The age standardized prevalence of AF is 0.77% in the participants enrolled in the present study. The number of AF cases aged ⋝35 years is 5.26 million according to 2010 Chinese Census. Most risk factors for AF, identified mainly in Western countries, are also detected in China.</p>

Reduction of atrial fibrillation in remotely monitored pacemaker patients: results from a Chinese multicentre registry / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Many recipients of implantable cardiac electronic devices have atrial fibrillation (AF) occurrences after device implantation, even if there is no previous history of AF, and some of the episodes are asymptomatic. The purpose of this study was to evaluate trends in AF burden following early AF detection in patients treated with pacemakers equipped with automatic, daily Home Monitoring function.</p><p><b>METHODS</b>Between February 2009 and December 2010, the registry recruited 701 pacemaker patients (628 dual-chamber, 73 biventricular devices) at 97 clinical centers in China. Daily Home Monitoring data transmissions were analyzed to screen for the AF burden. In-office follow-ups were scheduled for 3 and 6 months after implantation. Upon first AF (i.e., mode-switch) detection in a patient, screening of AF burden by Home Monitoring was extended for the next 180 days.</p><p><b>RESULTS</b>At least one episode of AF was observed in 22.9% of patients with dual-chamber pacemakers and in 28.8% of patients with biventricular pacemakers. The first AF detection in a patient occurred, on average, about 2 months before scheduled follow-up visits. In both pacemaker groups, mean AF burden decreased significantly (P < 0.05) over 180 days following first AF detection: from 12.0% to 2.5% in dual-chamber and from 12.2% to 0.5% in biventricular pacemaker recipients. The number of patients with an AF burden >10% per month was significantly reduced over 6 months of implantation in both dual chamber (38 patients in the first month vs. 21 patients in month 6, P < 0.05) and biventricular (7 patients in the first month vs. 0 patient in months 4-6, P < 0.05) pacemaker recipients.</p><p><b>CONCLUSIONS</b>Automatic, daily Home Monitoring of patients treated with cardiac pacemakers allows early detection of AF, and there is a gradual and significant decrease in AF burden.</p>

Home monitoring system improves the detection of ventricular arrhythmia and inappropriate shock / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The impact of home monitoring system in the early detection of ventricular arrhythmia and inappropriate shock in daily work is not clear. The aim of this study was to investigate the impact of home monitoring system on the early detection of ventricular arrhythmia and inappropriate shock in daily clinical practice.</p><p><b>METHODS</b>Cases of implantable cardioverter defibrillator (ICD) implantation with or without the home monitoring system from June 2010 to October 2011 at our center were reviewed. Follow-up was scheduled after implantation. Data relating to the home monitoring ICD were retrieved using a remote transmitter system. Data relating to the other devices were obtained during scheduled follow-up or unscheduled visits.</p><p><b>RESULTS</b>Our study involved 69 patients (mean age (68.4 ± 17.6) years, 64.3% males, 26 in the home monitoring group vs. 43 in the non-home monitoring group). In all, 561 ventricular arrhythmia episodes were detected in 17 patients (39.5%) in the non-home monitoring group: 495 episodes were ventricular tachycardia and 66 episodes were ventricular fibrillation; among these, 476 episodes of ventricular tachycardia and 45 episodes of ventricular fibrillation were appropriately diagnosed (96.1% and 68.2%, respectively). In the home monitoring group, 389 ventricular arrhythmia episodes were transmitted by the home monitoring system in nine patients (34.6%): 348 ventricular tachycardia episodes and 41 ventricular fibrillation episodes. Device detection was appropriate in 348 ventricular tachycardia episodes (100.0%) and 36 ventricular fibrillation episodes (87.8%). The home monitoring group showed a higher appropriate detection rate of ventricular tachycardia (P < 0.01) and ventricular fibrillation (P = 0.02). The proportion of inappropriate shock was comparable in the two groups (6/11 in the non-home monitoring group vs. 1/7 in the home monitoring group; P = 0.08).</p><p><b>CONCLUSIONS</b>The home monitoring ICD was able to provide information relating to inappropriate detection and shock earlier than conventional devices. It proved to be a reliable tool and has a strong potential to provide greater reaction time in the case of inappropriate shock.</p>

Improvement of P-wave dispersion is associated with a lower incidence of atrial fibrillation after cardiac resynchronization therapy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>P-wave dispersion (PWD) is a useful predictor of paroxysmal atrial fibrillation (AF). The effect of cardiac resynchronization therapy (CRT) on PWD and the prognostic implications of the improvement in PWD remain undefined. The aim of the study was to explore the clinical significance of the improvement of PWD after CRT.</p><p><b>METHODS</b>Electrocardiographic studies were performed before and three months after CRT in 81 patients (57 men and 24 women; age (60.5 ± 11.2) years) with standard CRT indication but no history of AF. A significant improvement of PWD (PWD responder) was defined as a relative decrease ≥ 20% from baseline PWD. The primary endpoints were new-onset AF detected by electrocardiogram (ECG) or CRT.</p><p><b>RESULTS</b>After (30.6 ± 7.5) months of follow-up, PWD responders (n = 43) had a significantly lower incidence of AF than did PWD nonresponders, 12% vs. 29% (P < 0.001). In Cox proportional hazard analysis, PWD responders was the only predictor of lower risk of new-onset AF (HR 0.33, 95% confidence interval 0.12 - 0.96, P = 0.033).</p><p><b>CONCLUSION</b>Improvement of P-wave dispersion after CRT was associated with a lower incidence of AF, which may be related to the significant improvement in left ventricular systolic function and the reverse modeling of the left atrium.</p>

Anticoagulation therapy in Chinese patients with non-valvular atrial fibrillation: a prospective, multi-center, randomized, controlled study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Non-valvular atrial fibrillation is associated with an increased risk of ischemic stroke; however, the appropriate intensity of anticoagulation therapy for Chinese patients has not been determined. The purpose of this study was to compare the safety and the efficacy of standard-intensity warfarin therapy, low-intensity warfarin therapy, and aspirin therapy for the prevention of ischemic events in Chinese patients with non-valvular atrial fibrillation (NVAF).</p><p><b>METHODS</b>A total of 786 patients from 75 Chinese hospitals were enrolled in this study and randomized into three therapy groups: standard-intensity warfarin (international normalized ratio (INR) 2.1 to 2.5) group, low-intensity warfarin (INR 1.6 to 2.0) group and aspirin (200 mg per day) group. All patients were evaluated by physicians at 1, 3, 6, 9, 12, 15, 18, 21 and 24 months after randomization to obtain a patient questionnaire, physical examination and related laboratory tests.</p><p><b>RESULTS</b>The annual event rates of ischemic stroke, transient ischemic attack (TIA) or systemic thromboembolism were 2.6%, 3.1% and 6.9% in the standard-intensity warfarin, low-intensity warfarin and aspirin groups, respectively (P = 0.027). Thromboembolic event rates in both warfarin groups were significantly lower than that in the aspirin group (P = 0.018, P = 0.044), and there was no significant difference between the two warfarin groups. Severe hemorrhagic events occurred in 15 patients, 7 (2.6%) in the standard-intensity warfarin group, 7 (2.4%) in the low-intensity warfarin group and 1 (0.4%) in the aspirin group. The severe hemorrhagic event rates in the warfarin groups were higher than that in the aspirin group, but the difference did not reach statistical significance (P = 0.101). The mild hemorrhagic and total hemorrhagic event rates in the warfarin groups (whether in the standard-intensity warfarin group or low-intensity warfarin group) were much higher than that in the aspirin group with the annual event rates of total hemorrhages of 10.2%, 7.6% and 2.2%, respectively, in the 3 groups (P = 0.001). Furthermore, there was no significant difference in all cause mortality among the three study groups.</p><p><b>CONCLUSION</b>In Chinese patients with NVAF, the warfarin therapy (INR 1.6 - 2.5) for the prevention of thromboembolic events was superior to aspirin.</p>

Potential predictors of non-response and super-response to cardiac resynchronization therapy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Although cardiac resynchronization therapy (CRT) is already an established treatment, the characteristics of patients who have an excellent response to CRT and those who get no benefit remain to be determined. The purpose of this study was to search for potential predictors of both non-response and super-response to CRT.</p><p><b>METHODS</b>Seventy-six consecutive patients who received CRT treatment were divided into group A (non-responders), group C (super-responders) and group B (responders exclusive of super-responders). Student's t test, Mann-Whitney test, Logistic regression and receiver operating characteristic curve were employed to identify potential predictors among the patients' demographic characteristics, clinical features, several electrocardiographic parameters before and after CRT implantation, and their pre-implant echocardiographic parameters.</p><p><b>RESULTS</b>Group A had the lowest 3-month left ventricular ejection fraction (LVEF). Group C had the smallest pre-implant left ventricular end-diastolic dimension (LVEDD), the shortest post-implant QRS duration, the smallest 3-month LVEDD and the highest 3-month LVEF. In addition, there was a trend of gradual change in percent of left bundle branch block, severity of pre-implant mitral regurgitation, pre-implant QRS dispersion, post-implant QRS duration as well as post-implant QRS dispersion from group A to group B and from group B to group C. Multivariable Logistic analysis revealed that only pre-implant LVEDD could predict CRT super-response. A pre-implant LVEDD of 68.5 mm was the cut-off value that identified super-responders with 87.5% sensitivity and 79.7% specificity. A pre-implant LVEDD of 62.5 mm identified super-responders with 50.0% sensitivity and 89.8% specificity.</p><p><b>CONCLUSIONS</b>Predictors of a CRT non-response remain unclear at present. But it is credible that patients with a smaller left ventricle would have a better chance to become super-responders to CRT.</p>

Single center experience with intrathoracic impedance monitoring / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The Medtronic InSync Sentry is the first available cardiac resynchronization therapy defibrillator (CRT-D) which can monitor fluid status by measuring intrathoracic impedance. This study was designed to observe the effectiveness of intrathoracic impedance monitoring on detecting aggravation of heart failure.</p><p><b>METHODS</b>We retrospectively analyzed the clinical data of 14 consecutive patients. Patients were regularly followed up every 3 - 6 months after the implantation. At each visit, interrogation of the device was done. Patients were instructed to inform the researcher on hearing the device alert, and to take extra 40 milligrams of furosemidum if they had aggravated symptoms later. If the symptoms could not be relieved, they were asked to see a doctor. Data about heart failure hospitalization were collected from the medical record.</p><p><b>RESULTS</b>During 18 - 48 months follow-up, a total of 7 patients encountered 28 alert events. On one hand, alert events appeared before all deteriorated symptoms and heart failure hospitalizations. On the other hand, there were 23 alerts followed by deterioration of heart failure symptoms, and 2 alerts related to 2 hospitalizations caused by pulmonary infection in one patient. Only 5 patients were hospitalized 10 times for deterioration of cardiac function.</p><p><b>CONCLUSION</b>The function of intrathoracic impedance monitoring is reliable in predicting deterioration of heart failure.</p>

Clinical characteristics and outcome of 32 patients with long-QT syndrome accompanied with torsade de pointes / 中华心血管病杂志

<p><b>OBJECTIVE</b>To summarize the clinical characteristics and outcome of patients with long-QT syndrome (LQTs) accompanied with torsade de pointes.</p><p><b>METHODS</b>Thirty-two eligible patients were included in this study. Clinical and electrocardiographic data were analyzed and telephone or out-patient follow-up were made in all patients.</p><p><b>RESULTS</b>There were 15 patients with inherited LQTs (h-LQTs) and 17 patients with acquired LQTs (a-LQTs). There are more women (n = 24) than men (n = 8). β blockers, potassium and magnesium supplement were the basic therapy for h-LQTs patients, bivent pacemaker was implanted in 2 patients and implantable cardioverter defibrillator was implanted in 5 patients. Ventricular tachyarrhythmias and syncope occurred in 4 patients during (39.4 ± 25.1) months follow-up. In 17 a-LQTs patients, one patient with dilated cardiomyopathy died suddenly and another patient with implanted cardioverter defibrillator experienced one ventricular tachycardia during (30.9 ± 13.3) months follow-up.</p><p><b>CONCLUSIONS</b>The prognosis in h-LQTs and a-LQTs patients with structure heart disease is poor. ICD or CRT-D therapy is suggestive for a-LQTs patients with structure heart disease.</p>

Usefulness of previsualization of the cardiac venous system by 64-slice computed tomography in patients with heart failure underwent cardiac resynchronization therapy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the value of 64-slice computed tomography (MDCT) in previsualization the cardiac veins anatomy before the implantation of cardiac resynchronization therapy (CRT).</p><p><b>METHODS</b>The 64-slice CT scans of 21 patients [10 men, age (61.6 ± 9.7) years] were obtained and analyzed before the implantation of CRT. Retrograde coronary venography was performed during intraoperational fluoroscopy. The coronary sinus (CS) and the main tributaries were measured.</p><p><b>RESULTS</b>Similar images to those obtained during the CRT implantation procedure were obtained by MDCT in 71% of the patients. The coronary sinus was clearly visible in all cases, the measured ostium was (12.1 ± 4.2) mm, and the angle between the CS and the vertical plane was (99 ± 12) degrees. In 90% of patients, at least one vein was clearly visible in the target area. Among the target veins, the posterolateral vein was visible in most cases (86%) and the lateral vein was visible in 48% of the patients.</p><p><b>CONCLUSION</b>MDCT is an effective and noninvasive method for previsualization of the cardiac venous system, which may facilitate optimal left ventricular lead positioning for CRT implantation.</p>

Nifekalant hydrochloride terminating sustained ventricular tachycardia accompanied with QT dispersion prolongation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ventricular tachycardia (VT) and ventricular fibrillation are the main reasons causing sudden cardiac death. This study aimed to investigate the effects of nifekalant hydrochloride (NIF) on QT dispersion (QTd) in treating VT.</p><p><b>METHODS</b>A total of 16 consecutive patients suffered sustained VT was included and then randomly divided into two groups according to the administration duration of NIF. In long-time group (group L), patients were injected with NIF continuously for at least 12 hours after a bolus dose. The patients in short-time group (group S) were injected with NIF just for 1 hour.</p><p><b>RESULTS</b>There were 7 of all 10 episodes of VT which were terminated by NIF, including 4 episodes in group L were stopped over 1 hour after continuous infusion of NIF. One patient suffered from torsade de pointes. Electrocardiography analysis indicated that QTd was significantly decreased 12 hours after stopping of infusing NIF compared with that when VT stopped ((45.4 +/- 22.1) ms vs. (73.4 +/- 33.2) ms, P < 0.01), and the corrected QTd (QTcd) decreased too ((47.8 +/- 22.9) ms vs. (78.3 +/- 36.5) ms, P < 0.01). There was a positive correlation between the increase in QTd and dose of administrating NIF (P < 0.01), so was QTcd (P < 0.01).</p><p><b>CONCLUSIONS</b>More administration of NIF indicates higher terminating rate of VT and more QTd prolongation. However, the safety is acceptable if several important issues were noticed in using NIF, such as serum potassium concentration, stopping side-effect related agents, and carefully observing clinical responses.</p>

Prognostic factors affecting the all-cause death and sudden cardiac death rates of post myocardial infarction patients with low left ventricular ejection fraction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Post myocardial infarction (post-MI) patients with low left ventricular ejection fraction (LVEF) have been candidates for an implantable cardioverter-defibrillator (ICD) since the Multicenter Automatic Defibrillator Implantation Trail II (MADIT II). However, due to the high costs of ICDs, widespread usage has not been accepted. Therefore, further risk stratification for post-MI patients with low LVEF may aid in the selection of patients that will benefit most from ICD treatment.</p><p><b>METHODS</b>Four hundred and seventeen post-MI patients with low LVEF (< or = 35%) were enrolled in the study. All the patients received standard examination and proper treatment and were followed up to observe the all-cause death rate and sudden cardiac death (SCD) rate. Then COX proportional-hazards regression model was used to investigate the clinical factors which affect the all-cause death rate and SCD rate.</p><p><b>RESULTS</b>Of 55 patients who died during (32 +/- 24) months of follow-up, 37 (67%) died suddenly. After adjusting for baseline clinical characteristics, multivariate COX proportional-hazards regression model identified the following variables associated with death from all causes: New York Heart Association (NYHA) heart failure class > or = III (Hazard ratio: 2.361), LVEF < or = 20% (Hazard ratio: 2.514), sustained ventricular tachycardia (Hazard ratio: 6.453), and age > or = 70 years (Hazard ratio: 3.116). The presence of sustained ventricular tachycardia (Hazard ratio: 6.491) and age > or = 70 years (Hazard ratio: 2.694) were specifically associated with SCD.</p><p><b>CONCLUSIONS</b>In the post-MI patients with low LVEF, factors as LVEF < or = 20%, age > or = 70 years, presence of ventricular tachycardia, and NYHA heart failure class > or = III predict an adverse outcome. The presence of sustained ventricular tachycardia and age > or = 70 years was associated with occurrence of SCD in these patients.</p>

Reasons for pacing leads abandonment during pacemaker replacement: a single center experience with 235 cases / 中华心血管病杂志

<p><b>OBJECTIVE</b>To analyse the reasons for pacing lead abandonment during pacemaker replacement.</p><p><b>METHOD</b>Clinical data of patients underwent permanent pacemaker replacement between Jan 1st, 1976 to Dec 31st 2006 in Fuwai Hospital were obtained and the reasons for pacing leads abandonment were analyzed.</p><p><b>RESULTS</b>Pacemaker was replaced in 1023 patients during this period and 235 pacing leads were abandoned, 131 leads (55.7%) were abandoned for leads malfunction, including leads body fracture (35, 14.9%), isolation defects (10, 4.3%), dislocations (10, 4.3%) and excessively high threshold values (76, 32.3%). Other reasons for leads abandonment were infection (50, 21.3%), incompatibility between the leads and new generator (30, 12.8%), need to degrade the pacing system (13, 5.5%) and other rare reasons (11, 4.7%).</p><p><b>CONCLUSION</b>The most often reason for leads abandonment during pacemaker replacement is lead malfunction, including lead body fracture, isolation defect, dislocation and excessively high threshold value of the leads.</p>

Decrease of plasma N-terminal pro beta-type natriuretic peptide as a predictor of clinical improvement after cardiac resynchronization therapy for heart failure / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>N-terminal pro beta-type natriuretic peptide (NT pro BNP) has been shown to predict the prognosis and could guide the treatment of heart failure. We aimed to investigate the values of NT pro BNP in predicting the clinical response to cardiac resynchronization therapy (CRT).</p><p><b>METHODS</b>A total of 44 patients with chronic heart failure (34 male and 10 female, mean age of (58 +/- 13) years, New York Heart Association (NYHA) class 3.3 +/- 0.5, QRS duration (150 +/- 14) milliseconds) who underwent successful implantation of a CRT system were enrolled in this study. Pharmacotherapy remained stable during the first 3 months of follow-up. Plasma levels of NT pro BNP were evaluated before and 3 months after implantation. Clinical, echocardiographic and exercise parameters were monitored at each clinical visit after CRT implantation. Receiver operating characteristic analysis and a paired t test were performed to analyze the data.</p><p><b>RESULTS</b>After a mean of (16.3 +/- 5.5) months of follow-up, 11 nonresponders were identified. CRT resulted in a significant reduction in NT pro BNP ((1.70 +/- 1.28) vs (1.07 +/- 0.88) pmol/ml, P < 0.001) in responders. Percentage change in NT pro BNP level (DeltaBNP%) was a statistically significant predictor of long term clinical improvement at 3 months of follow-up.</p><p><b>CONCLUSIONS</b>DeltaBNP% from baseline to 3 months of follow-up is a predictor of long term response to CRT. NT pro BNP may be a simple method for monitoring the effects of CRT.</p>

Replication of Bombyx mori Densonucleosis Virus (Zhenjiang isolate) in different silkworm strains / 生物工程学报

The invertebrate parvovirus Bombyx mori Densonucleosis Virus type 3(Zhenjiang isolate), named BmDNV-3, is a kind of bidensovirus. The most obvious characteristic in the genome of BmDNV-3 is that it has 2 sets of DNA molecular (VD1, VD2),and each of them is encapsidated respectively in the form of single-stranded liner DNA ( + VD1, - VD1, + VD2, - VD2) in equal percentage. So the BmDNV-3 has 4 kinds of virions. Furthermore the sequence of BmDNV-3 is able to encode DNA polymerase itself. Some strains of silkworm revealed complete resistance to BmDNV-3, so they didn' t fall sick. To investigate the difference in the process of infection and replication between the 2 virions ( VD1, VD2) of this bidensovirus, and the difference of the increment in the resistant or susceptible host, the 5th instar larvae of the susceptible silkworm strain (HUABA 35) and the resistant silkworm strain(QIUFENG d) were inoculated determinate dose of BmDNV-3 by oral ingestion. Then the midgut were collected at 9 timepoints. The silkworm cytoplasm actin A3 was used to be normalized gene, so the number of cells in collected tissue could be determined. The result shows that whatever in the susceptible silkworm strain or in the resistant one, the copies of VD1 and VD2 in the genome of BmDNV-3 collected at the different timepoint were almost at the equal level respectively, so that the VD1 and VD2 were replicated with synchronization. The process of infection in the susceptible silkworm strain was devided into 3 partitions, latent period( 2 - 12 hours post inoculation), exponential phase (12 - 36 hours post inoculation)and stationary phase (36- 96 hours post inoculation and there are about 2 x 10(5) copies per cell) . In the resistant silkworm strain, the virus were replicated at a very low level, that was from 6 - 10 copies 2 hours post inoculation to 150 - 200 copies 96 hours post inoculation (about 20 times) . So we predict that the resistance in some of the silkworm strains from BmDNV-3 was a kind of chronic representation that the host carried virus without being caused flacherie.

Rapid disruption of Bombyx mori nucleopolyhedrovirus orf60 by red recombination system / 生物工程学报

BmNPV bacmid constructed recently and Red recombinant system were used to rapidly disrupted Bombyx monri nucleopolyhedrovirus (BmNPV) orf60 in Escherichia coli (E. coli) BW25113. BmNPV bacmid isolated from E. coli BmDH10Bac was electroporated into E. coli BW25113, which harbors plasmid pKD46 encoding lamda Red recombinase,to produce E. coli BW25113-Bac, which could be used for gene deletion of BmNPV. A linear fragment was amplified by PCR from plasmid pKD3 (containing a chloramphenicol acetyltransferase gene cat) using a pair of primers with length of 63bp,which had 45 bp homologous to the orf60 gene and 18bp homologous to cat sequences. The linear fragment was electroporated into E. coli BW25113-Bac and homologous recombination occurred between the linear fragment and orf60 with the help of lamda Red recombinase. Three specific primer pairs were used to confirm the replacement of orf60 by cat gene. Western blot analysis showed that orf60 was not expressed in BmN cells infected with knockout bacmid.

Organization and transcription strategy of genome of Bombyx mori bidensovirus (China isolate) VD1 / 生物工程学报

To better understand the genomic structure and function of Bombyx mori bidensovirus (China isolate) VD1, the VD1 was purified and cloned into the pUC119 vector, and the complete nucleotide sequence of VD1 was determined. Sequence analysis showed that VD1 genome consisted of 6543 nts including inverted terminal repeats (ITRs) of 224 nts. In the viral genome, three major open reading frames (ORF1, ORF2 and ORF3) in the plus strand and one major ORF (ORF4) in the complementary strand were identified. Comparison of the complete genome sequence between Bombyx mori bidensovirus (China isolate) and BmDNV-2 (Yamanashi isolate) showed an identity of 98.4% in VD1, with a total number of 104 bp substitutions and 1 bp insertions found in Bombyx mori bidensovirus (China isolate), the highly variable regions were mainly located in VD1 ORF3 and VD1 ORF4. Northern blotting revealed that VD1 contained 1.1 kb and 1.5 kb transcript in the left-half 'plus' strand, and one transcript about 3.3 kb of 'minus' strand in the right-half. Sequencing of 3' and 5' ends of transcript products showed the 1.1 kb transcript started at nt 290 and ended at nt 1437, the 1.5 kb transcript was found to start nt 1423 and ended at 2931, and the 3.3 kb transcript was found to start nt 6287 and ended at nt 2922. Therefore, the 1.5 kb transcript in the left-half plus' strand and 3.3 kb transcripts of minus' strand in the right-half overlapped for 10 nts at the 3' ends. These results indicate that this virus employs a transcription strategy that is radically different from that of the other reported DNVs.

Impact of automatic threshold capture on pulse generator longevity / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The automatic, threshold tracking, pacing algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response following each pacemaker stimulus. This function was assumed to be not only energy saving but safe. This study estimated the extension in longevity obtained by AutoCapture (AC) compared with pacemakers programmed to manually optimized, nominal output.</p><p><b>METHODS</b>Thirty-four patients who received the St. Jude Affinity series pacemaker were included in the study. The following measurements were taken: stimulation and sensing threshold, impedance of leads, evoked response and polarization signals by 3501 programmer during followup, battery current and battery impedance under different conditions. For longevity comparison, ventricular output was programmed under three different conditions: (1) AC on; (2) AC off with nominal output, and (3) AC off with pacing output set at twice the pacing threshold with a minimum of 2.0 V. Patients were divided into two groups: chronic threshold is higher or lower than 1 V. The efficacy of AC was evaluated.</p><p><b>RESULTS</b>Current drain in the AC on group, AC off with optimized programming or nominal output was (14.33 +/- 2.84) mA, (16.74 +/- 2.75) mA and (18.4 +/- 2.44) mA, respectively (AC on or AC off with optimized programming vs. nominal output, P < 0.01). Estimated longevity was significantly extended by AC on when compared with nominal setting [(103 +/- 27) months, (80 +/- 24) months, P < 0.01). Furthermore, compared with the optimized programming, AC extends the longevity when the pacing threshold is higher than 1 V.</p><p><b>CONCLUSION</b>AC could significantly prolong pacemaker longevity; especially in the patient with high pacing threshold.</p>