The Application Study Of Feature Tracking And Myocardial Tissue Mapping Technology Of CMR In Obstructive Sleep Apnea Hypopnea Syndrome

Background:Obstructive sleep apnea hypopnea syndrome(OSAHS),characterized by repetitive partial or complete upper respiratory tract obstruction during sleep,causes a series of pathophysiological mechanisms due to intermittent nocturnal hypoxia,which is the basis of the structural change and dysfunction of the heart.At present,echocardiography is the main study method on OSAHS.Compared with echocardiography,cardiac magnetic resonance(CMR)is the gold standard imaging technique for structure and function measurement.With the development of CMR new technology,feature tracking(FT)can be used to analyze myocardial deformation ability;late gadolinium enhancement(LGE)imaging can be used to assess focal myocardial fibrosis;T1 mapping quantitative techniques can be used to identify diffuse myocardial fibrosis;T2 mapping can be used to quantify the degree of myocardial inflammatory response and myocardial edema.However,there are a few studies on CMR in OSAHS patients,and the majority of the studies have significant cardiovascular diseases at present.Therefore,it is extremely important to conduct a comprehensive CMR study on OSAHS patients without major cardiovascular diseases.Purpose:To explore the changes of cardiac structure and function in patients with OSAHS without major cardiovascular diseases and to evaluate the characteristics of myocardial tissue by the CMR technique.Materials and methods:This prospective study was approved by the Institutional Review Board of Guangdong Provincial People’s Hospital,Guangdong Academy of Medical Sciences.After the polysomnography(PSG)examination,the subjects were divided into control group(AHI<5 events/h,n=17)and all OSAHS group(AHI>5 events/h,n=25),and then the all OSAHS group was further divided into mild-moderate OSAHS group(5≤AHI<30 events/h,n=10)and the severe OSAHS group(AHI>30 events/h,n=15).All subjects underwent CMR study within one week after the PSG examination.The population characteristics data and CMR indexes were compared between the control group and all OSAHS groups,and between the three group of control,mild-moderate OSAHS and severe OSAHS by appropriate methods.According to the normality assessment,the Pearson or Spearman correlation was used for correlation analysis.To confirm the significant impact of OSAHS on LV remodeling parameters,including left ventricular mass index(LVMi),left ventricular mass/volume ratio(LVMVR),and cellular volume index(CVi),multiple linear regression analyses were applied.Results:Except for 10 patients had hypertension in OSAHS group,all subjects did not have any other cardiovascular diseases and related risk factors.There was no significant difference in left ventricular ejection fraction(LVEF)between the two groups and the three groups comparison.The LVMi value showed significant statistical differences between the two groups and the three groups(P<0.05)and showed an upward trend with the increase of OSAHS severity.There were no significant differences in the left ventricular global longitudinal strain(GLS),global circumferential strain(GCS),global radial strain(GRS)and right ventricular GLS between the two groups and the three groups.The right ventricular free wall strain was increased in OSAHS patients,and showed an upward trend with the increase of OSAHS severity(P<0.05).There were no significant differences in left atrial volume,left atrial strain and strain rate indexes between the two and three groups.Any LGE pattern didn’t observed in all subjects.T2 mapping showed that there was no significant difference in the overall T2 value of the left ventricle middle short-axis between the two groups and the three groups.The Medis software analysis of T1 mapping showed that extracellular volume(ECV)value of left ventricle middle short-axis in all OSAHS group was lower than that in the control group(24.6± 1.9%vs.26.3±2.6%,P=0.02);Native T1 values of left ventricular middle,and apical short-axis in severe OSAHS group were lower than those in control and mild-moderate OSAHS group(P<0.05).The CVi,matrix volume index(MVi)and CVi-MVi in the OSAHS group were significantly higher than those in the control group,and the differences were statistically significant.Multiple linear regression analysis showed that the OSAHS severity was independent risk factors for the increase of LVMi,CVi and CVi-MVi indexes.Conclusion:The indexes of LVMi and CVi are increased in OSAHS patients,and the increased LVMi is mainly from the CVi,and the severity of OSAHS is an independent risk factor for the increase of LVMi and CVi.We speculate that OSAHS patients may experience the adaptive stage of pathological remodeling on the basis of FT analysis results and no evidence of focal or diffuse myocardial fibrosis.