不同左心室构型甲亢性心肌病模型兔血浆B型脑钠肽与心功能的关系

Correlation of brain natriuretic peptide and cardiac function of rabbits with hyperthyroid cardiomyopathy exhibiting different left ventricular geometries

背景:随着甲状腺功能亢进症(简称甲亢)发病率的增加,过量的甲状腺激素对心肌的毒害作用不容忽视,而B型脑钠肽作为心衰定量标志物,对甲亢性心肌病的心功能及心肌损害程度的早期估测有着良好的应用前景。目的:探索不同左心室构型兔甲亢性心肌病血浆B型脑钠肽水平变化及其与心功能的相关性。方法:随机取20只新西兰纯种白兔,连续4周腹腔注射左旋甲状腺激素(45μg/kg),建立甲亢动物模型。出现易怒好斗、体质量减轻、饮食量增加等典型的甲亢症状兔为成功建模的实验兔共18只。对甲亢模型兔超声测量左心室数据,然后按照Ganau等的标准将此18只甲亢模型兔分为向心性肥厚组(n=7)与离心性肥厚组(n=11)。另10只兔每天腹腔注射5 mL生理盐水作为对照组。结果与结论:向心性肥厚组和离心性肥厚组血浆B型脑钠肽水平明显高于对照组(P<0.01),而离心性肥厚组较向心性肥厚组血浆B型脑钠肽水平明显升高(P<0.01)。与对照组相比,向心性肥厚组及离心性肥厚组二尖瓣环平均舒张期峰值血流速度减低(P<0.01),同时离心性肥厚组二尖瓣环平均收缩期峰值血流速度亦减低(P<0.01)。B型脑钠肽与舒张期峰值速度及收缩期峰值速度呈负相关(均P<0.01)。提示不同左心室构型甲亢性心肌病兔的血浆B型脑钠肽水平可较敏感的反映心功能的变化及其心肌损害程度。

BACKGROUND： Toxic effects of excessive thyroid hormone on myocardium can not be ignored with the increased incidence of hyperthyroidism. As a quantitative marker of heart failure, brain natriuretic peptide has a good application prospect to estimate the changes of cardiac function and myocardial damage in hyperthyroid cardiomyopathy. OBJECTIVE： To explore the correlation of brain natriuretic peptide and cardiac function of rabbits with hyperthyroid cardiomyopathy exhibiting different left ventricular geometries. METHODS： Twenty New Zealand purebred rabbits were used in this study. Hyperthyroidism model was established by intraperitoneal injection of levothyroxine（45 μg/kg） for 4 weeks. The success of establishing model is defined upon the appearance of irritation, decreased body weight and increased appetite. Totally 18 rats were successfully established. The left ventricular data of hyperthyroidism rabbits were measured by conventional echocardiography. According to the classification of Ganau et al, the 18 hyperthyroidism rabbits were divided into two groups： concentric hypertrophy（n=7） and eccentric hypertrophy（n=11）. In addition, ten rats, receiving intraperitoneal injection of 5 m L saline per day, were taken as the control group. RESULTS AND CONCLUSION： Plasma brain natriuretic peptide level of rabbits in the concentric hypertrophy and eccentric hypertrophy groups was obviously higher than that of the control group（all P〈0.01）, and the level in the eccentric hypertrophy group was obviously higher than in the concentric hypertrophy group（P〈0.01）. Compared with the control group, the average peak diastolic velocity of mitral ring was significantly lower in the concentric hypertrophy and eccentric hypertrophy groups（all P〈0.01）, the average peak systolic velocity of mitral ring was also lower in the eccentric hypertrophy group（P〈0.01）. The peak systolic and diastolic velocity had a negative correlation with brain natriuretic peptide（all P〈0.01）. Experimental findings indicate that brain natriuretic peptide is a sensitive indicator to reflect the cardiac function and myocardial damage in rabbits with hyperthyroid cardiomyopathy, exhibiting different left ventricular geomeies.