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>

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>

Right phrenic injury after radiofrequency catheter ablation of atrial tachycardia at crista terminalis / 中华医学杂志(英文版)

A 62-year-old woman with frequent occurrence of symptomatic atrial tachycardia with a foci located at the root of the upper crista terminalis was found to have right diaphragm paresis after receiving a total of 8 radiofrequency energy deliveries (40-60 W, 50-60ºC) and a total duration of 540 seconds of ablation therapy (7Fr 8 mm deflectable ablation catheter). The right diaphragm paresis remained resolved up to 14 months after the procedure as confirmed by repeated chest X-rays.

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>

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>

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>

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>

Clinical study of 39 Chinese patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>There are few studies on the clinical profile of Chinese patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). The purpose of this study was to describe the clinical characteristics of ARVD/C patients from China, particularly to define the features of electrocardiograph and treatment outcomes.</p><p><b>METHODS</b>Thirty-nine patients hospitalized in Fu Wai Cardiovascular Hospital from 1998 to 2006 were included. The data were obtained from the medical archive and the follow-up records.</p><p><b>RESULTS</b>Of these patients 33 were male and 6 female (age at the first presentation was (34.9 +/- 9.8) years). The most common symptoms were palpitation (62%) and syncope (44%). Right precordial QRSd >or= 110 ms was detected in 69% of the patients, epsilon wave in 59%, and a ratio of QRSd in V(1) + V(2) + V(3)/V(4) + V(5) + V(6) >or= 1.2 in 82%. The most frequent features of electrocardiogram in patients without right bundle-branch block were T-wave inversions and S-wave upstroke in V(1)-V(3) >or= 55 ms (96% and 90% of 28 patients, respectively). Radiofrequency catheter ablation (RFCA) for ventricular tachycardia (VT) was successful in 15 (68%) of 22 patients. The recurrence rate of VT was 46% (7/15) during the follow-up of (16.7 +/- 11.2) months. Seven patients had cardioverter/defibrillator (ICD) implanted plus drug therapy and 17 patients took antiarrhythmic drugs alone. During the follow-up of (35.6 +/- 19.0) months, all patients with ICD implanted received at least one appropriate ICD shock. One patient died of ventricular fibrillation suddenly and one patient underwent heart transplantation for progressive biventricular heart failure during the drug therapy alone.</p><p><b>CONCLUSIONS</b>This study demonstrated the clinical and ECG features of the 39 ARVD/C Chinese patients. ICD provided life-saving protection by effectively terminating malignant arrhythmias, and the high recurrence of VT was the major problem of RFCA therapy.</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>

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>

Efficacy of cardiac resynchronization therapy-defibrillator for treating patients with chronic heart disease / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observed the clinical efficacy of cardiac resynchronization therapy-defibrillator (CRT-D) in selected patients with chronic heart failure one year after implantation.</p><p><b>METHODS</b>Seventeen patients with drug-refractory heart failure received CRT-D implantation (6 patients were implanted with InSync Sentry). The underlying heart diseases were dilated cardiomyopathy in 12 patients and ischemic heart disease in 5 patients. There were 13 patients with a history of ventricular tachycardia/ventricular fibrillation.</p><p><b>RESULTS</b>CRT-D were successfully implanted in all patients without complication. The mean left ventricular pacing threshold was 1.6 V. The defibrillation threshold was no more than 20 J. During a mean follow-up of 13 months, no death occurred and LV function was improved. The shock induced by ventricular tachycardia was delivered in 5 patients and alarming due to heart failure occurred twice in 1 patient.</p><p><b>CONCLUSIONS</b>The implantation of CRT-D for treating refractory heart failure patients is feasible and safe. The application of CRT-D was associated with an improved cardiac function and a reduced risk of sudden cardiac death.</p>

Clinical and ECG features of arrhythmogenic right ventricular cardiomyopathy: a retrospective analysis of 31 cases / 中华心血管病杂志

<p><b>OBJECTIVE</b>To retrospectively analyze the clinical and electrocardiographic features of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC).</p><p><b>METHODS</b>The clinical, electrocardiographic features and the efficacy of various therapies were analyzed in 31 patients (27 males) diagnosed as ARVC according to the criteria established by European Society of Cardiology.</p><p><b>RESULTS</b>The averaged age when the ARVC was first diagnosed was (34.7 +/- 9.4) years (19 - 58 years), palpitation was present in 28 patients (90.3%) and syncope in 13 patients (41.9%), a family history of sudden death was present in 1 patient. Dilatated right ventricle was documented in 29 patients by echocardiography and (or) magnetic resonance imaging (MRI), 2 of them with dilated left ventricles. ECG changes included: T wave inversion, mostly seen in precordial leads (100%); epsilon (epsilon) wave (54.8%); QRS duration >or= 110 ms in V(1) to V(3) (83.9%); reduced extremity amplitude (41.9%); the first degree of AV block (22.6%); sustained VT (100%) including 15 monomorphic VT (48.4%) and 16 polymorphic VT (51.6%). The mean values of QRS duration in leads of V(1 - 3) [(120.8 +/- 13.7) ms] was significantly longer than that in V(4 - 6) [(99.4 +/- 13.7) ms, P < 0.05]. Fourteen patients underwent radiofrequency catheter ablation (RFCA) with an immediate success rate of 78.6% (11/14). During follow up (18.3 +/- 10.2) months, VT reoccurred in 6 patients (54.5%). The remaining 17 patients were treated with conventional medications, 7 of them were medicated under implanted cardioverter defibrillator (ICD). During the follow-up (35.6 +/- 19.0) months, VT reoccurred in 11 patients (64.7%) and one patient died suddenly.</p><p><b>CONCLUSIONS</b>ARVC patients developed symptoms at mid-30s with significant ECG changes including appearance of an epsilon wave, T wave inversion and QRS duration >or= 110 ms in leads of V(1 - 3). The long term therapy efficacy was not satisfactory both for RFCA and conventional medications and ICD implantation should be recommended to patients with ARVC.</p>

Complications of cardiac resynchronization therapy in patients with congestive heart failure / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Previous clinical studies have suggested that patients with congestive heart failure and intraventricular conduction delay could benefit from cardiac resynchronization therapy (CRT). Implantation of left ventricular lead is a complex procedure with some potential for complications. This study was conducted to analyse the complications of CRT in patients with congestive heart failure.</p><p><b>METHODS</b>Totally 117 patients, 86 males and 31 females, mean age of 53 years, with congestive heart failure and intraventricular conduction delay were enrolled in this study. Venography was performed on all patients. Different types of coronary sinus leads were used to pace the left ventricle.</p><p><b>RESULTS</b>Left ventricular lead was attempted to implant through coronary sinus for all the 117 patients and was successfully implanted in 111 patients. The success rate was 94.9%. Main complications rate was 6.8%, including coronary sinus dissection in 4 patients, phrenic nerve stimulation required lead repositioning in 2 patients and lead dislodgement in 2 patients.</p><p><b>CONCLUSIONS</b>It is feasible and safe to pace left ventricle through coronary sinus. However, there are some procedural complications.</p>

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Implantable cardioverter defibrillator (ICD) is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital.</p><p><b>METHODS</b>From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis.</p><p><b>RESULTS</b>No arrhythmic event was detected in 12/50 (24%) patients during the period of follow-up. Among the remaining patients, 11 (22%) experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia (VT) and 108 ventricular fibrillation (VF) episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings (ATPs) and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 (14.3%) inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 (26.9%) inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation (AF) with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation.</p><p><b>CONCLUSIONS</b>About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.</p>

Short-term effect of cardiac resynchronization therapy in patients with ischaemic or nonischaemic cardiomyopathy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Patients with heart failure were candidates for cardiac resynchronization therapy (CRT) regardless of underlying aetiology. This study observed the effect of CRT in patients with ischaemic or nonischaemic cardiomyopathy.</p><p><b>METHODS</b>One hundred and forty-two patients with refractory chronic heart failure and left bundle branch block received cardiac resynchronization therapy, 91 men and 51 women, average age 60 years. Left ventricular ejection fraction (LVEF) was severely depressed (mean 29%), left ventricular end diastolic diameter (LVEDD) enlarged (mean 72 mm) and QRS width was lengthened (mean 147 ms). Ninety-eight had nonischaemic cardiomyopathy and 44 had ischaemic cardiomyopathy.</p><p><b>RESULTS</b>After cardiac resynchronization therapy, the heart function was significantly improved. The mean LVEF increased from 29% to 36% after pacing. In patients with nonischaemic cardiomyopathy, the LVEF was improved from 28% to 37%, and in patients with ischaemic cardiomyopathy, the LVEF was improved from 30% to 36%. No significant difference of the improvement was found between the two groups (P > 0.05).</p><p><b>CONCLUSIONS</b>Cardiac resynchronization therapy could significantly improve cardiac function in patients with chronic heart failure regardless of the underlying heart disease.</p>

Assessment of cardiac function and synchronicity in subjects with isolated bundle branch block using Doppler imaging / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Using tissue Doppler imaging and conventional echocardiographic technique, we examined the cardiac function and synchronicity in individuals with isolated right bundle branch block (RBBB) or left bundle branch block (LBBB) and assessed the relationship between QRS duration and synchronicity.</p><p><b>METHODS</b>Subjects with isolated RBBB (n = 20), LBBB (n = 10) and normal controls (n = 20) were studied with conventional echocardiography and tissue Doppler imaging. The difference between aortic and pulmonary preejection intervals was defined as interventricular delay. Parameters in septum and lateral wall were measured using tissue Doppler imaging, including peak sustained systolic velocity (S(M)), peak early (E(M)) and late (A(M)) diastolic velocities as well as time to peak velocities (T(S), T(E) and T(A)).</p><p><b>RESULTS</b>Subjects with LBBB had lower S(M) and longer T(S) than did the RBBB and control groups (P < 0.05, P < 0.001 respectively). A significant difference was observed in E(M), being the lowest in the LBBB and the highest in the control group (P < 0.05). Moreover, T(E) was longer in the LBBB group compared with the other two groups (P < 0.001). Both A(M) and T(A) were similar among three groups (P > 0.05). In the bundle branch block groups, one ventricle lagged about 40 ms behind the other. A significant correlation was found between interventricular delay and QRS duration (r = 0.713, P < 0.001).</p><p><b>CONCLUSIONS</b>Cardiac ventricles were not well synchronized with one ventricle lagging about 40 ms behind the other in subjects with LBBB or RBBB, even though only LBBB group showed barely perceptible, impaired cardiac function. In addition, QRS duration and cardiac asynchronicity were positively correlated.</p>

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>

Clinical study on 29 pacemaker and defibrillator lead fractures / 中华心血管病杂志

<p><b>OBJECTIVE</b>To analyze major probable causes, locations and remedies of lead fractures in implanted pacemaker and implanted cardioverter defibrillator (ICD) .</p><p><b>METHODS</b>From January 1982 to November 2004, on all the pacemakers and ICDs implanted at this hospital, lead fractures were detected timely by regular telemetric programmed testing, chest radiography and electrocardiography. Appropriate remedial actions were given and follow up visits were done to verify the results.</p><p><b>RESULTS</b>Of all the 4698 pacemakers and 161 ICDs, there were 29 lead fractures on 31 leads with an incidence rate of 0.6%. The incidence rate of lead fracture was 0.9% for pacemakers/defibrillators implanted by subclavian venipuncture, while it was 0.4% for pacemakers/defibrillators implanted by cephalic venotomy (P = 0.04). Fracture locations: 22 cases at the sub clavicle, 6 cases in the pacemaker pocket, and 1 case in the right ventricle. Among the 29 cases, 24 were implanted with additional new leads, 3 cases whose atrial leads were fractured were switched from DDD mode to VVI. All the patients were followed up for an average of 5.6 months +/- 16.1 months. In one patient, the lead was removed through thoracotomy due to infection of exposed lead.</p><p><b>CONCLUSIONS</b>Cephalic venotomy is the first choice for pacemaker and ICD implantation, and the second choice is subclavian venipuncture in the outer part of subclavian vein, which has a higher incidence rate of lead fracture. Most lead fractures are detected at the region of medial subclavian. Regular follow-up can help timely detect fractures, so that the cases can be dealt with properly.</p>