背景:长期暴露于低压和低氧的高海拔环境中可能会导致心脏的结构和功能异常。心肌应变是评估心肌功能障碍的敏感指标,监测心肌应变对高原心脏相关疾病的早期诊断和治疗具有重要意义。本研究应用心脏磁共振组织追踪技术(CMR-TT)评价高原环境下大鼠左心室心肌功能和结构的变化。
方法:6周龄雄性大鼠随机分为高原低氧大鼠(高原组,n=21)作为实验组和普通大鼠(普通组,n=10)作为对照组。高原组大鼠从成都运输(海拔:360m),位于中国西南部高原上的一座城市,到青藏高原(海拔:3850m),玉树,中国,然后在那里喂养12周,平原组大鼠在成都(海拔360米)饲喂,中国。使用7.0T心脏磁共振(CMR)评估左心室射血分数(EF),舒张末期容积(EDV),收缩末期容积(ESV)和每搏输出量(SV),以及心肌应变参数,包括峰值全球纵向(GLS),径向(GRS),和周向应变(GCS)。将大鼠安乐死并在磁共振成像扫描后获得心肌活检。
结果:高原大鼠的左心室GLS和GRS较普通大鼠低(P<0.05)。然而,左心室EDV差异无统计学意义,ESV,SV,EF和GCS与普通年夜鼠比拟(P>0.05)。
结论:高原低压低氧环境暴露12周后,左心室整体应变部分减少,心肌受损,虽然整个心脏射血分数仍然保留,在监测心功能方面,心肌应变比射血分数更敏感。
BACKGROUND: Long-term exposure to a high altitude environment with low pressure and low oxygen could cause abnormalities in the structure and function of the heart. Myocardial strain is a sensitive indicator for assessing myocardial dysfunction, monitoring myocardial strain is of great significance for the early diagnosis and treatment of high altitude heart-related diseases. This
study applies cardiac magnetic resonance tissue tracking technology (CMR-TT) to evaluate the changes in left ventricular myocardial function and structure in rats in high altitude environment.
METHODS: 6-week-old male rats were randomized into plateau hypoxia rats (plateau group, n = 21) as the experimental group and plain rats (plain group, n = 10) as the control group. plateau group rats were transported from Chengdu (altitude: 360 m), a city in a plateau located in southwestern China, to the Qinghai-Tibet Plateau (altitude: 3850 m), Yushu, China, and then fed for 12 weeks there, while plain group rats were fed in Chengdu(altitude: 360 m), China. Using 7.0 T cardiac magnetic resonance (CMR) to evaluate the left ventricular ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV), as well as myocardial strain parameters including the peak global longitudinal (GLS), radial (GRS), and circumferential strain (GCS). The rats were euthanized and a myocardial biopsy was obtained after the magnetic resonance imaging scan.
RESULTS: The plateau rats showed more lower left ventricular GLS and GRS (P < 0.05) than the plain rats. However, there was no statistically significant difference in left ventricular EDV, ESV, SV, EF and GCS compared to the plain rats (P > 0.05).
CONCLUSIONS: After 12 weeks of exposure to high altitude low-pressure hypoxia environment, the left ventricular global strain was partially decreased and myocardium is damaged, while the whole heart ejection fraction was still preserved, the myocardial strain was more sensitive than the ejection fraction in monitoring cardiac function.