Preliminary Study On The Mechanism Of Cardiac Injury Induced By Radiation Using Speckle Tracking Technique Combined With Myocardial Fibrosis Markers

Objective:The myocardial strain capacity of patients with thoracic malignant tumor after radiotherapy was evaluated by two-dimensional spot tracking technology,and the serum cytokines CTGF and TGF-β₁in the control patients were compared to explore the mechanism of radioactive heart injury and the relationship between radioactive myocardial fibrosis and cardiac function reduction.Materials and methods:We selected 40 patients with malignant tumor who first received chest radiotherapy in the department of radiology and treatment of our hospital from December 2021 to December 2022.After screening,30 patients who met the criteria for inclusion were finally selected as the radiotherapy group.Blood samples were collected and centrifuged one day before radiotherapy（T0）,at the end of radiotherapy（T1）,and three months after radiotherapy（T2）.The content of CTGF and TGF-β₁in the serum of patients at three time points was determined by ELISA.At the same time,routine echocardiographic examination was carried out on the enrolled patients at T0,T1 and T2 respectively,and the following clear two-dimensional images and parameters were obtained under the standard section,mainly including:the diameter of ascending aorta（AO）,the diameter of left atrial end systolic（LA）,the diameter of right ventricular end diastolic（RVIDd）,the thickness of end diastolic ventricular septum（IVSd）,the diameter of left ventricular end diastolic（LVIDd）,and the thickness of left ventricular posterior wall at end diastolic（LVPWd）.The left ventricular ejection fraction（LVEF）was measured by Simpson biplane method.The early diastolic mitral flow velocity（E peak）,the late diastolic mitral flow velocity（A peak）,the E/A value,and the maximum peak velocity e’and E/e’values at the septal and lateral wall sides of the early diastolic mitral annulus were measured by spectral Doppler.At the same time,it is necessary to record the dynamic figures of the short axis view of the mitral valve,the short axis view of the papillary muscle,the short axis view of the apex,and the two chamber view,the three chamber view,and the four chamber view of the apex for more than three cardiac cycles to finally complete the offline analysis.In addition,a total of 30 normal people of the same age who went to the hospital for health examination at the same time were selected as the control group（T）to perform the same examination.There was a significant positive correlation betweenΔGLS,MHD and the content of CTGF and TGF-β₁in the serum of patients with thoracic malignant tumor after three months of intensity-modulated radiation therapy（r values were 0.73,0.77,0.73 and 0.69,respectively,P<0.05）.There was also a significant positive correlation between the percentage of the irradiated heart volume in the total heart volume at the radiation dose>5Gy and>30Gy and the content of CTGF and TGF-β₁in the serum of patients after radiotherapy（r values were 0.606,0.637,0.753 and 0.687,respectively,P<0.05）.Result:Compared with the control group（T）,the general clinical data such as sex,age,height and weight of patients in the radiotherapy group before radiotherapy（T0）had no significant difference（P>0.05）.Compared with the control group（T）,the conventional echocardiography parameters and strain parameters before radiotherapy（T0）in the radiotherapy group had no significant difference（P>0.05）.Compared with the control group（T）,the conventional echocardiographic parameters and strain parameters of patients in the radiotherapy group before radiotherapy（T0）had no statistical difference（P>0.05）.At the end of radiotherapy（T1）and 3 months after radiotherapy（T2）,the conventional echocardiographic parameters AO,LA,RVIDd,IVSd,LVIDd,E peak,A peak,E/A value,septal e’,lateral e’,E/e’,LVEF had no statistical difference compared with the baseline before radiotherapy（T0）（P>0.05）.Over time,although LVEF tends to decrease gradually,it is still within the normal range.The GLS at the end of radiotherapy（T1）and 3 months after radiotherapy（T2）was significantly lower than that at the baseline before radiotherapy（T0）（P<0.05）,and there was no statistical change in GCS and GRS（P>0.05）.GLS at 3 months after radiotherapy（T2）was also significantly lower than that at the end of radiotherapy（T1）（P<0.05）,but there was no significant difference between GCS and GRS（P>0.05）.The levels of TGF-β₁and CTGF in serum of patients before radiotherapy（T0）were not significantly different from those of control group（T）（P>0.05）.The levels of TGF-β₁and CTGF in serum of patients at the end of radiotherapy（T1）and 3months after radiotherapy（T2）were significantly higher than the baseline level before radiotherapy（T0）（P<0.05）.The levels of TGF-β₁and CTGF in the serum of patients three months after radiotherapy（T2）were also significantly higher than those at the end of radiotherapy（T1）,and the difference was statistically significant（P<0.05）.Correlation analysis There was a positive correlation betweenΔGLS,MHD and CTGF,TGF in the serum of patients with thoracic malignant tumor 3 months after intensity-modulated radiation therapy（r values were 0.73,0.77,0.73 and 0.69,respectively,P<0.05）.There was also a positive correlation between the percentage of the irradiated volume of the heart in the total volume of the heart when the radiation dose was greater than 5Gy and greater than 30Gy and the content of CTGF and TGF-β₁in the serum of patients at 3 months after the end of radiotherapy（r values were 0.606,0.637,0.753 and 0.687,respectively,P<0.05）.Conclusion:1.Two dimensional speckle tracking imaging is more sensitive than conventional two-dimensional echocardiography in evaluating the changes of left ventricular systolic function in patients with chest malignant tumor at subclinical stage after radiotherapy.2.The value of GLS of left ventricular myocardium after radiotherapy decreased gradually with the prolongation of radiotherapy time.3.At the early stage of radiotherapy,the contents of CTGF and TGF-β₁in the serum of patients with central muscle fibrosis increased significantly after radiotherapy,and gradually increased with the prolongation of radiotherapy time.4.Myocardial damage may be related to the dose of local radiation.And theΔGLS of left ventricle,MHD,V5,V30 have a significant positive correlation with the increase of myocardial fibrosis index CTGF,TGF-β₁content.Early detection of such damage and targeted protection and treatment are of great significance to the long-term prognosis and quality of life of patients.