法洛四联症右室流出道心肌超微结构特点

目的　研究法洛四联症 (TOF)右室流出道心肌细胞的超微结构变化及年龄特点。方法　取符合电镜观察条件的小儿TOF 13例 ,对照组为同期年龄匹配的房间隔缺损、室间隔缺损患儿 7例。用透射电镜进行右室流出道心肌超微结构观察。结果　对照组可见心肌的肌原纤维及线粒体结构基本正常。TOF右室流出道的心肌存在很多超微结构异常的心肌细胞 ,主要表现为心肌纤维排列紊乱 ;在心肌纤维内 ,肌原纤维排列方向紊乱 ,丧失同向走行的性质 ;肌膜下方及肌纤维间异常地积聚着大量形态各异的线粒体及线粒体变性 ;部分肌节失去正常结构而出现长度不等及不全肌节 ;Z线改变明显 ;心肌细胞的固有极性被破坏等。上述异常变化随着年龄增加 ,尤其是 1岁后心肌细胞的超微结构异常明显加重。结论　 1.TOF右室流出道的心肌组织存在着很多超微结构异常的心肌细胞 ;2 .TOF患儿应尽早手术治疗 ,1岁内手术矫治能避免不可逆性心肌损伤

Ultrastructural characters of myocardium in right ventricular outflow tract of children with tetralogy of fallot

Objective To study the ultrastructural changes of myocardium in the right ventricular outflow tract of tetralogy of fallot (TOF) in different age groups.Methods Total 13 patients with TOF aged 3 months to 6 years and weighed 5.5-16.5 kg were selected as study group, and 7 patients matched in age with small atrial septal defect(ASD) or ventricular septal defect(VSD) as the control group. To observe the ultrastuetural characters of myocardium in the right ventricular outflow tract by electronic microscopic observation (JEM 1200).Results In control group,the muscle fibers showed an oriented arrangement and mitochondria were well distributed beneath the sarcolemma or in the field of myofibrils, Z-bands were equal and clear.In study group, the sarcolemma often formed pouches filled with abnormal mitochondria and the muscle fibers showed a disoriented arrangement. In addition, the myofibrils showed hypercontraction, even lost normal structure, and the Z-bands were thickened. The ultrastructural changes of myocardium became more severe after 1 year old than ever.Conclusions More abnormal myocytes exist in right ventricular tract of TOF. It is suggested that the TOF operation would be performed as early as possible to avoid aggravated myocardium.