| BackgroundChronic thromboembolic pulmonary hypertension(CTEPH)is the only type of pulmonary hypertension with potential cure,which is characterized by pulmonary artery thromboembolic automatization and fibrosis,secondary to pulmonary vascular remodeling resulting in vascular stenosis or occlusion,and eventually leading to the progressive increase of pulmonary vascular resistance and pulmonary arterial pressure.If left untreated,pulmonary hypertension continues to develop will leading to right heart failure and even death.Therefore,early assessment of right ventricular function is of great significance for the diagnosis and treatment of the disease.Currently,right heart catheterization is the gold standard for the diagnosis of pulmonary hypertension,but it is invasive and cannot evaluate right ventricular morphological changes.Two-dimensional echocardiography is safe and easy to operate,but the evaluation of right ventricular function relies on geometric assumptions and has many technical limitations.Cardiac magnetic resonance(CMR)images with high contrast and resolution are the gold standard for ejection fraction(EF)quantification,and can be used to evaluate myocardial tissue injury,cardiac structure and function,and pulmonary artery hemodynamic changes.The purpose of this study was to investigate the efficacy of CMR in detecting CTEPH and the value of evaluating ventricular function and severity of disease.Part 1 The value of cardiac magnetic resonance in evaluating chronic thromboembolic pulmonary hypertensionObjectiveThe purpose of this study was to use CMR to analyze ventricular function and left ventricular myocardial strain in patients with CTEPH and to conduct a comparative study with healthy controls,to explore the feasibility of CMR to evaluate cardiac function in patients with CTEPH and the ability to detect pulmonary hypertension.Materials and methodsThirty-three patients with CTEPH confirmed by RHC were prospectively collected as the CTEPH group,including 10 males and 23 females,aged 30-78 years,with an average age of(55.15±13.33)years,and an average body surface area of(1.68±0.17)m~2.In addition,thirty-nine healthy volunteers were included as the control group,including 15 males and 24 females,aged 33～79 years old,with an average age of(53.64±12.87)years old and an average body surface area of(1.67±0.17)m~2.All subjects underwent CMR balanced fast field echo sequence scanning.The parameters measured and calculated from CMR cine images by the post-processing software include:left ventricular end-diastolic volume(LVEDV),left ventricular end systolic volume(LVESV),left ventricular stroke volume(LVSV),left ventricular ejection fraction(LVEF),left ventricular myocardial mass(LVMM),right ventricular end-diastolic volume(RVEDV),right ventricular end systolic volume(RVESV),right ventricular stroke volume(RVSV),right ventricular ejection fraction(RVEF),right ventricular myocardial mass(RVMM),right ventricular wall thickness(RVWT),right ventricular fractional area change(RVFAC),tricuspid annular plane systolic excursion(TAPSE),ventricular mass index(VMI),LVEDV index(LVEDVI),LVESV index(LVESVI),LVSV index(LVSVI),LVMM index(LVMMI),RVEDV index(RVEDVI),RVSV index(RVESVI),RVSVI index(RVSVI),RVMM index(RVMMI).The left ventricular myocardial strain indexes were obtained by CMR-FT technique,including global radial strain(GRS),global circumferential strain(GCS),global longitudinal strain(GLS)and strain values of each segment(basal,middle and apex).Statistical analysis of cardiac function parameters in the CTEPH and control groups was performed using two independent samples t-test.Linear correlation analysis was performed between the overall left ventricular myocardial strain parameters and cardiac function parameters using Pearson correlation analysis.The area under the curve(AUC)of each assessed index was calculated using the receiver operating characteristic curve(ROC curve)to compare the efficacy of each index in detecting pulmonary hypertension(PH).p<0.05 was considered statistically significant.Results1.Comparison of basic information and right and left cardiac functional outcomes between CTEPH and control groups:LVEDVI,LVSVI,LVEF,LVMMI,RVSVI,RVEF,RVFAC,and TAPSE in the CTEPH group were lower or significantly lower than those in the control group(P<0.01 or P<0.001);RVEDVI,RVESVI,RVMMI,VMI,and RVWT were significantly higher in the CTEPH group than in the control group(P<0.001);There were no statistically significant differences in age,sex and BSA between the two groups(P>0.5).2.Comparison of global and local strain results of left ventricular myocardium between CTEPH group and control group:Except RS at the apex,GRS,GCS,GLS and strain values at all segments of left ventricle myocardium were lower in the CTEPH group compared with the control group(P<0.01).3.Results of correlation analysis between global left ventricular myocardial strain parameters and cardiac function parameters in the CTEPH group:Correlation analysis of global left ventricular myocardial strain parameters and cardiac function parameters showed that left ventricular GRS was positively correlated with LVEF,RVEF and RVFAC(P<0.005),and negatively correlated with RVEDVI(P<0.05).Both GCS and GLS were negatively correlated with LVEF,RVEF and RVFAC(P<0.005),and positively correlated with RVEDVI(P<0.005).Left ventricular myocardial strain parameters were highly correlated with LVEF,among which GCS had the highest correlation with LVEF(r=-0.738,P<0.001).When LVEF decreased,the correlation between GRS,GCS and GLS of left ventricular and LVEF decreased.4.Comparison of efficacy of CMR’s cardiac function parameters in detecting PH:ROC curve analysis showed that among the 5 indexes,right ventricular morphological and functional parameters generally had a higher efficacy in detecting PH,and combined with RVMMI,VMI,RVWT,RVFAC and TAPSE had the highest efficacy in detecting PH,with an AUC of 0.984.ConclusionCMR can accurately,objectively and quantitatively evaluate the morphological and functional alterations of RV and the myocardial strain of LV in patients with CTEPH.The efficacy of right ventricle morphological and functional parameters of CMR for detecting PH is high,and the efficacy of the combined index is the highest,which can be used as an auxiliary diagnostic index to systematically evaluate the pathophysiological status of patients with CTEPH.Part 2 Cardiac magnetic resonance imaging to evaluate the severity of chronic thromboembolic pulmonary hypertensionObjectiveTo investigate the correlation between cardiac function parameters of CMR and hemodynamic parameters of RHC,and the changes of cardiac function between CTEPH groups with different severity,so as to explore the value of CMR in evaluating the severity of CTEPH patients.Materials and methodsThirty-one patients with CTEPH confirmed by RHC were prospectively collected,including 10 males and 21 females,with a mean age of(54.71±13.23)years,a mean m PAP of(41.42±13.32)mm Hg,and a mean PVR of(8.61±5.23)WU.There were 12 cases with mild PH,with a mean m PAP(29.58±2.97)mm Hg,mean PVR(4.17±2.16)WU;9 cases with moderate PH,mean m PAP(38.78±2.86)mm Hg,mean PVR(8.28±2.47)WU;10 cases with severe PH,mean m PAP(58.00±8.59),mean PVR(14.22±4.31)WU.Another thirty-nine healthy volunteers were included.All patients underwent CMR balanced fast field echo sequence scanning.The parameters measured and calculated from CMR cine images by the post-processing software include:left ventricular end-diastolic volume(LVEDV),left ventricular end systolic volume(LVESV),left ventricular stroke volume(LVSV),left ventricular ejection fraction(LVEF),left ventricular myocardial mass(LVMM),right ventricular end-diastolic volume(RVEDV),right ventricular end systolic volume(RVESV),right ventricular stroke volume(RVSV),right ventricular ejection fraction(RVEF),right ventricular myocardial mass(RVMM),right ventricular wall thickness(RVWT),right ventricular fractional area change(RVFAC),tricuspid annular plane systolic excursion(TAPSE),ventricular mass index(VMI),LVEDV index(LVEDVI),LVESV index(LVESVI),LVSV index(LVSVI),LVMM index(LVMMI),RVEDV index(RVEDVI),RVSV index(RVESVI),RVSVI index(RVSVI),RVMM index(RVMMI).The left ventricular myocardial strain indexes were obtained by CMR-FT technique,including global radial strain(GRS),global circumferential strain(GCS),global longitudinal strain(GLS).Pearson correlation coefficient was used to analyze the correlation between cardiac function parameters and m PAP and PVR.One-way analysis of variance was used for comparison of quantitative data among three groups,and LSD-t test was used for two-way comparison between groups.P<0.05 was considered statistically significant.Results1.Correlation analysis of CMR’s cardiac function parameters with m PAP and PVR in CTEPH patients:RVMMI,VMI and RVWT measured by CMR were positively correlated with m PAP and PVR measured by RHC(P<0.05),with RVWT having higher correlation with m PAP and PVR(r=0.616,r=0.657);RVEF,RVFAC,TAPSE and LVSVI measured by CMR were negatively correlated with m PAP and PVR measured by RHC(P<0.05),among which RVEF,RVFAC,and TAPSE were moderately correlated with m PAP and PVR;the remaining cardiac function parameters were not significantly correlated with m PAP and PVR.2.Comparison of the efficacy of CMR’s cardiac function parameters for detecting different severity of CTEPH:Compared with the control group,RVESVI increased,RVEF decreased,RVWT thickened,and RVFAC decreased in the mild CTEPH group;LVEDVI,LVSVI,and LVEF decreased,left ventricular GRS,GCS,and GLS decreased,RVEDVI and RVESVI increased,RVSVI,RVEF,RVFAC,and TAPSE decreased in the moderate CTEPH group.RVEF,RVWT and RVFAC were all highly effective in detecting mild CTEPH,among which RVWT had the highest efficiency,with AUC of 0.91,sensitivity and specificity of 91.7%and 84.6%,respectively.Both left and right ventricular function parameters and left ventricular myocardial strain were more effective in the detection of moderate CTEPH,but parameters related to right ventricular function were more effective.3.Comparison of cardiac function parameters between LVEF≥50%CTEPH group and LVEF<50%CTEPH group and control group:The RVEF in the control group,LVEF≥50%CTEPH group and LVEF<50%CTEPH group showed a stepwise decrease,with statistical differences among all three groups(P<0.001);GRS,GCS and GLS were reduced in the LVEF<50%CTEPH group compared with the LVEF≥50%CTEPH group and the control group(P<0.05),and There was no statistically significant difference in the global left ventricular myocardial strain values between the LVEF≥50%CTEPH group and the control group(P>0.05).4.Comparison of CMR’s cardiac function parameters between RVEF≥40%CTEPH group and RVEF<40%CTEPH group and control group:LVEF and left ventricular myocardial strain were lower in the RVEF<40%CTEPH group than in the RVEF≥40%CTEPH group and the control group(P<0.01),and there were no statistical differences in LVEF and left ventricular strain between RVEF≥40%group and control group(P>0.1).RVEDVI,RVESVI,RVMMI,VMI,RVWT,RVFAC,and TAPSE were statistically significantly different between the RVEF<40%CTEPH group and the control group and the RVEF≥40%CTEPH group(P<0.001).And the differences in RVWT and RVFAC between the RVEF≥40%group and the control group were statistically significant(P<0.05).ConclusionThere are different degrees of correlation between the morphological and functional indexes of right ventricle measured by CMR and the hemodynamic indexes measured by RHC,and it can detect different degrees of CTEPH,which can effectively evaluate the severity of disease in patients with CTEPH.Patients with impaired ejection fraction have further reduced cardiac function and left ventricular myocardial strain than patients with preserved ejection fraction.patients with CTEPH with preserved RVEF have early right ventricular systolic dysfunction,and RVWT and RVFAC can reflect early right ventricular dysfunction more sensitively. |
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