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目的观察兔心脏压力超负荷左心室肥大(LVH)发展过程中心电图(ECG)的电学改变能否早于超声心动图(UCG)的形态学改变,进一步探讨ECG在高血压性LVH早期诊断中的意义。方法日本大耳白兔40只,随机分成实验组25只和对照组15只。实验组采用肾上腹主动脉次全结扎法建立心脏压力超负荷LVH模型,对照组除不行腹主动脉缩窄外,其余处理同实验组。两组兔均于术前及术后2、4、6、8周测量血压,描记同步12导联ECG并测量各导联R波和QRS波的振幅、心电轴、QRS波时限和QTc间期;同时做超声心动图,测量室间隔及左心室下后壁厚度、左心室收缩和舒张末期内径以及心功能等参数。术前及术后8周拍摄X线胸片,测量心胸比值。之后处死动物,取左心室测量其质量指数,并进行病理检查。结果实验组兔术后血压逐渐上升,X线下心胸比值增加,左心室质量指数增大,病理所见心肌细胞肥大,部分变性或坏死。超声所见:左心室下壁、后壁及室间隔厚度术后即逐渐增大,E/A逐渐降低,4周后与对照组相比差异有统计学意义(P<0.05);左心室收缩和舒张末期内径术后4周始逐渐增大,6周后与对照组相比差异有统计学意义(P<0.05);左心室射血分数逐渐降低,术后8周与对照组相比差异有统计学意义(P<0.05)。ECG表现:心电图Ⅱ、Ⅲ、aVF及胸前各导联术后R波及QRS波振幅逐渐增高,术后2周开始与对照组相比差异均有统计学意义(P<0.05);QRS波时限和QTc术后呈逐渐递增趋势,4周后与对照组相比差异有统计学意义(P<0.05)。对照组兔上述各指标术前、术后差异无统计学意义。结论在兔压力超负荷LVH发展过程中,ECG电学改变早于UCG反映的结构改变,ECG对高血压性LVH具有一定的早期诊断价值。
Objective To investigate whether electrical changes of electrocardiogram (ECG) in rabbits with cardiac hypertensive left ventricular hypertrophy (LVH) are earlier than echocardiographic (UCG) morphological changes and to further investigate the role of ECG in the early diagnosis of hypertensive LVH significance. Methods Forty Japanese white rabbits were randomly divided into experimental group (n = 25) and control group (n = 15). In the experimental group, the model of cardiac hypertensive LVH was established by subarachnoid aortic ligation. In the control group, the abdominal aorta was not narrowed except for the abdominal aorta, and the rest were treated with the experimental group. Blood pressure was measured before operation and at 2, 4, 6, and 8 weeks after operation in both groups. The synchronized 12-lead ECG was measured and the amplitude of R-wave and QRS-wave, ECG axis, QRS wave duration and QTc Echocardiography was performed at the same time to measure the parameters of interventricular septum and posterior wall thickness of left ventricle, left ventricular systole, end-diastolic dimension and cardiac function. 8 weeks before and after radiography X-ray film, measuring heart-chest ratio. Animals were sacrificed, the left ventricular mass index was measured, and pathological examination. Results The blood pressure of rabbits in experimental group increased gradually, the ratio of cardiothoracic and thoracic to X-ray increased, the mass index of left ventricle increased, and the histopathology showed hypertrophy and partial degeneration or necrosis of cardiomyocytes. Ultrasound findings: the thickness of the left ventricular wall, posterior wall and interventricular septum gradually increased after surgery, E / A decreased gradually, compared with the control group after 4 weeks, the difference was statistically significant (P <0.05); left ventricular contraction And end-diastolic diameter gradually increased at 4 weeks after operation, and there was significant difference (P <0.05) after 6 weeks compared with control group; left ventricular ejection fraction decreased gradually, There was statistical significance (P <0.05). The ECG showed that the amplitudes of R wave and QRS wave in ECG Ⅱ, Ⅲ, aVF and each lead of chest increased gradually, and there was significant difference (P <0.05) between the two weeks after operation and the control group; QRS wave time limit And QTc showed a gradual increasing trend after 4 weeks compared with the control group, the difference was statistically significant (P <0.05). The control group of the above indicators of preoperative and postoperative differences were not statistically significant. Conclusion During the development of LVH in rabbits with pressure overload, ECG changes earlier than that of UCG. ECG has some early diagnostic value for hypertensive LVH.