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.

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>

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>