The Effects of Trimetazidine on QT-interval Prolongation and Cardiac Hypertrophy in Diabetic Rats / Os Efeitos da Trimetazidina no Prolongamento do Intervalo QT e na Hipertrofia Cardíaca em Ratos Diabéticos

Abstract Background: Trimetazidine (TMZ) is an anti-ischemic drug. In spite of its protective effects on cardiovascular system, there is no scientific study on the usefulness of TMZ treatment for prolonged QT interval and cardiac hypertrophy induced by diabetes. Objectives: To evaluate the effects of TMZ on QT interval prolongation and cardiac hypertrophy in the diabetic rats. Methods: Twenty-four male Sprague-Dawley rats (200-250 g) were randomly assigned into three groups (n = 8) by simple random sampling method. Control (C), diabetic (D), and diabetic administrated with TMZ at 10 mg/kg (T10). TMZ was administrated for 8 weeks. The echocardiogram was recorded before isolating the hearts and transfer to a Langendorff apparatus. Hemodynamic parameters, QT and corrected QT interval (QTc) intervals, heart rate and antioxidant enzymes were measured. The hypertrophy index was calculated. The results were evaluated by one-way ANOVA and paired t-test using SPSS (version 16) and p < 0.05 was regarded as significant. Results: The diabetic rats significantly indicated increased hypertrophy, QT and QTc intervals and decreased Left ventricular systolic pressure (LVSP), Left ventricular developed pressure (LVDP), rate pressure product (RPP), Max dp/dt, and min dp/dt (±dp/dt max), heart rate, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase in the heart. Treatment with TMZ in the diabetic animals was significantly improved these parameters in comparison to the untreated diabetic group. Conclusions: TMZ improves QTc interval prolongation and cardiac hypertrophy in diabetes.

Resumo Fundamento: A trimetazidina (TMZ) é uma droga anti-isquêmica. Apesar de seus efeitos protetores sobre o sistema cardiovascular, não há estudos científicos sobre a utilidade do tratamento com TMZ para o intervalo QT prolongado e a hipertrofia cardíaca induzida pelo diabetes. Objetivo: Avaliar os efeitos da TMZ no prolongamento do intervalo QT e na hipertrofia cardíaca em ratos diabéticos. Métodos: Vinte e quatro ratos machos Sprague-Dawley (200-250 g) foram distribuídos aleatoriamente em três grupos (n = 8) pelo método de amostragem aleatória simples. Controle (C), diabético (D) e diabético administrado com TMZ a 10 mg/kg (T10). A TMZ foi administrada por 8 semanas. O ecocardiograma foi registrado antes de isolar os corações e transferir para um aparelho de Langendorff. Foram medidos os parâmetros hemodinâmicos, intervalo QT e intervalo QT corrigido (QTc), frequência cardíaca e enzimas antioxidantes. O índice de hipertrofia foi calculado. Os resultados foram avaliados pelo one-way ANOVA e pelo teste t pareado pelo SPSS (versão 16) e p < 0,05 foi considerado significativo. Resultados: Os ratos diabéticos indicaram hipertrofia aumentada, intervalos QT e QTc e diminuição da pressão sistólica no ventrículo esquerdo (PSVE), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), Max dp/dt e min dp/dt (± dp/dt max), frequência cardíaca, superóxido dismutase (SOD), glutationa peroxidase (GPx) e catalase no coração. O tratamento com TMZ nos animais diabéticos melhorou significativamente esses parâmetros em comparação com o grupo diabético não tratado. Conclusões: A TMZ melhora o prolongamento do intervalo QTc e a hipertrofia cardíaca no diabetes.

Biomechanics of cardiac blood pumping and electrical changes of the heart / 医用生物力学

Despite the significant progress in the fields of electrocardiology and cardiac biomechanics, theoretic limitations still exist and many problems on mechanism underlying the electrical changes of the heart still remain to be solved. Based on the fact that experimental studies deeply rely on the microscopic and quantitative information, and the electrical changes and mechanical activities of the heart have long been treated as two individual processes, dynamic forces generated in the whole spring-loading system during the cardiac contraction and relaxation were discussed first from a macroscopic view. Next, the temporal co-relationship between the electrical and mechanical processes after “excitation-contraction coupling” was particularly identified, which indicated that the intertwined electrical and mechanical activities, in their nature, are integrated parts of a same process. Finally, once all the electrical and mechanical “gating” mechanisms were taken into consideration, the electrical changes of the heart could be classified into three different phases: the preceding excitation formation and conduction, the myogenic changes during ventricular contraction, and the complete restoration of the heart both mechanically and electrically during active relaxation.

Radiofrequency ablation of 1065 cases of arrhythmia patients / 医学研究生学报

Objective : To investigate the efficacy and safty of radiofrequency ablation for arrhythmia. Methods: The clinical data of 1 065 patients with arrhythmia by Radiofrequency ablation treatment were analyzed retrospectively, including 537 cases of atrioventricular nodal reentrant tachycardia, 386 cases of atrioventricular reentrant tachycardia, 59 cases of ventricular premature, 26 cases of ventricular tachycardia, 35 cases of atrial flutter, and 8 cases of paroxysmal atrial fibrillation. Results:The procedural succeed rate was 96. 80% , and complication was 1. 56%. Conclusion: Radiofrequency ablation was an safe and effective method in treating arrhythmia.

The study on examination methods of clinical electrocardiology in medical postgraduates training / 中华医学教育探索杂志

How to improve the teaching quality is urgent and significant at present.Based on reforming the teaching methods,the authors have studied the new methods of medical postgraduate examination since 2005 including the assessments on practical skills,the level of mastering knowledge,self learning and innovating ability and the criterion of giving a mark,which have been applied for three years and achieved the aim and the effect in clinical electro-cardiology teaching.