ABSTRACT
Objective To investigate changes in gait level of patients after hip replacement, the variation trend of bone mineral density (BMD) around the prothesis was studied, so as to reveal the influence pattern of gait level at postoperative initial and long-term stages on bone reomodeling. Methods Based on adaptive bone remodeling theory, the finite element model of femer-prosthesis was developed. The BMD distribution was calculated using the initial and long-term gait level after hip replacement as the remodeling parameters. Gruen method was applied to quantify the BMD changes. Results At the postoperative initial stage, obvious variations existed in constant gait group and changing gait group. The maximum difference occurred in low gait group, resulting in the decrease of BMD by 41% in greater trochanter region. The improvement of gait level would promote the enhancement of BMD in proximal and middle region of the prosthesis, resulting in the increase of BMD by 47%. Long-term gait recovery would promote BMD recovery in middle and end region of prosthesis, with BMD increase by 2%-9%. Conclusions The research findings provide guidance for rehabilitation process of patients after hip replacement.
ABSTRACT
Objective@#To investigate the risk factors of ventricular arrhythmias in patients with Brugada syndrome.@*Methods@#Clinical data of 60 Brugada syndrome patients admitted in the department of cardiology of the First Affiliated Hospital of Nanjing Medical University from March 2003 to December 2016 were collected and retrospectively analyzed. The age at diagnosis was (43.2±13.1) years (0.6-83.0 years), 98.3% were males (n=59), and the patients were followed up to (92±41) months (12-169 months). The 12-lead surface electrocardiogram (ECG) recorded at the time of diagnosis and showing the highest type 1 ST elevation, either spontaneously or after provocative drug test, was used for the analysis. Patients were divided into ventricular arrhythmia (VA, n=12) group and non-ventricular arrhythmia (non-VA, n=48) group depending on the presence or absence of clinical VA event. The demographic data and ECG data of the 2 groups were compared, and the independent risk factors of VA events were analyzed by stepwise logistic regression.@*Results@#Incidence of family history of sudden death (7/12 vs. 22.9% (11/48)) and percentage of type 1 ST elevation in the peripheral ECG leads (6/12 vs. 16.67% (8/48)) were significantly higher in VA group than in non-VA group (both P<0.05). Max Tpeak-Tend (Max-Tpe) interval ((144±53)ms vs. (110±16)ms) and dispersion of Tpe ((74±50)ms vs. (43±17)ms) were significantly higher in VA group than in non-VA group (both P<0.05). The area under receiver operating characteristic (ROC) curves for the Max-Tpe interval was 0.693 and Max-Tpe interval ≥140 ms was determined as an optimized cutoff point with increased risk of VA event, which had a sensitivity of 50.0%, a specificity of 98.0%, a positive predictive value of 85.7%, and a negative predictive value of 88.7% for predicting VA event. The ROC curves for the dispersion of Tpe was 0.775 and dispersion of Tpe ≥45 ms was determined as an optimized cutoff point for predicting VA event, which had a sensitivity of 91.7%, a specificity of 64.6%, a positive predictive value of 39.3%, and a negative predictive value of 96.9% for predicting VA event. In multivariate analysis, Max-Tpe interval ≥140 ms (OR=27.53, 95%CI 1.07-706.77, P=0.045) and family history of sudden death (OR=24.63, 95%CI 2.05-295.38, P=0.011) were found to be the independent risk factors of arrhythmic events.@*Conclusions@#Max-Tpe interval ≥140 ms and family history of sudden death are risk factors of VA event in included patients with Brugada syndrome.