| Objectives The purpose of this study was to evaluate the flow field of left ventricle in different phases of cardiac cycle by using vector flow mapping(VFM)combined with treadmill exercise stress test(TESE)and to explore the changes of left ventricular function in patients with mild coronary artery atherosclerosis stenosis.Method Prospective collection of patients who were suspected coronary artery disease with chest pain,all patients underwent TESE before coronary angiography or coronary artery dual-source computed tomography.Relevant data was collected.34 patients with mild left anterior descending coronary artery stenosis were selected as the case group,and 36 patients without obvious coronary artery stenosis were selected as the control group in the same period.The echocardiographic images of apical fourchamber,three-chamber,and two-chamber views were collected at rest and early recovery period.The indexes of left ventricular diastolic function and systolic function were measured at the same time.The original images were imported into the VFM workstation for left ventricular flow field analysis.Record vortex area,circulation(cir),the total energy loss(ELt),basal segment energy loss(ELb),middle segment energy loss(ELm),apical segment energy loss(ELa),energy loss reserve(EL-r)and energy loss reserve rate in isovolumic systolic period(S1),rapid ejection period(S2),slow ejection period(S3),isovolumic diastolic period(D1),rapid filling period(D2),slow filling period(D3)and atrial contraction period(D4).The intra-group and inter-group differences of these parameters were compared before and after exercise.Result 1.Comparison of general information between the case group and control group:The difference was not statistically significant in general data,serological indicators,echocardiography index,and TESE index between the two groups(P > 0.05).2.Comparison of vector flow mapping index between the two groups:(1)Qualitative analysis of left ventricular flow field using vector flow mapping in both groups Both the control group and the case group had relatively regular vortex formation and dissipation trends at rest or after exercise,and the distribution of EL increased after exercise.Compared with the control group,the streamline distribution of the case group was less regular.At rest the formation of the abnormal vortex of the left ventricle apical segment in S1 and D3,and middle segment in D1 had been observed.(2)Comparison of the vector flow mapping parameters between the control group and the case group at rest Compared with the control group,the S1 vortex area of the left ventricle in the resting case group was reduced(P<0.05),and the S3 vortex area was increased(P<0.05);the S1 ELm was higher(P<0.05),S2 ELm and ELa were higher(P<0.05);D1 ELt,ELb,ELm,ELa were higher(P<0.05);D2 ELt,ELb,ELm were lower(P<0.05);D3 ELb was higher(P<0.05);D4 ELa was higher(P<0.05).(3)Comparison of the vector flow mapping parameters between the control group and the case group after exercise Compared with the control group,the vortex area in D1 and D3 in the case group increased after exercise(P<0.001);D1,D2 cir increased after exercise(P<0.001);S2 ELt,ELb,ELm,and ELa were lower(P<0.001);S3 ELt and ELm were lower(P<0.001);D1 ELb was higher(P<0.05);D2 ELm and ELa were lower(P<0.05);D3 ELb was higher(P<0.05);D3 ELm and ELa were lower(P<0.05);D4 ELb was lower(P<0.05).(4)Comparison of the vector flow mapping parameters before and after exercise in the control group Compared with the resting state,the vortex area in S1,S3,D2,and D3 in the control group decreased after exercise(P<0.05);cir in S2,D1,D3,and D4 increased(P<0.05),and cir in D2 decreased(P<0.05);most total and segmental EL of each phase was higher(P<0.05),except for D2 ELb(P>0.05)).(5)Comparison of vector flow mapping parameters before and after exercise in the case group Compared with the resting state,in case group the vortex area in S3 and D2 decreased(P<0.001),and the vortex area in D1 increased(P<0.001);cir in S2,D1,D3,D4 increased(P<0.05);the total and segmental EL of each phase was mostly higher than in the resting state(P<0.05),except for D1 ELt,ELb,and D2 ELb(P>0.05).3.Comparison of energy loss reserve between the two groups Compared with the control group,S1 ELa-r in the case group was lower(P<0.05);S2 ELt-r,ELb-r,ELm-r,and ELa-r were lower(P<0.05);S3 ELt-r,ELb-r,ELm-r were lower(P<0.05);D1 ELt-r,ELb-r,ELm-r,ELa-r were lower(P<0.05);D2 ELa-r was lower(P<0.05);D3 ELt-r and ELa-r were lower(P<0.05);D4 ELm-r and ELa-r were lower(P<0.05).Compared with the control group,the S1 basal segment EL reserve rate of the case group was higher(P<0.05);the S2 left ventricle total,basal segment,middle segment,and apical segment EL reserve rate were lower(P<0.05);the reserve rate of the total left ventricle and the middle segment in S3 was lower(P<0.05);the EL reserve rate of the total left ventricle,the basal segment and the apical segment in D1 was lower(P<0.05);the reserve rate of D2 apical segment was lower(P<0.05);D3 total left ventricle and apical segment EL reserve rate were lower(P<0.05);D4 apical segment reserve rate was lower(P<0.05).4.Logistic regression and ROC curve analysis results Increased D1 ELb at rest would increase the risk of mild coronary artery stenosis(OR=1.537,95%CI 1.337~1.766,P<0.001);the increase of D1 vortex area after exercise would increase the risk of mild coronary artery stenosis(OR=1.005,95%CI 1.001~1.008,P<0.05);the decrease in S3 ELm after exercise would increase the risk of mild coronary artery stenosis(OR=0.543,95 %CI 0.452~0.652,P<0.001);S2 ELa-r decrease would increase the risk of mild coronary artery stenosis(OR=0.664,95%CI 0.578~0.762,P<0.05).When at rest D1 ELb cut-off value was 2.809,the AUC was 0.637,the sensitivity was 0.582,and the specificity was 0.847;when the D1 vortex area cut-off value after the exercise was 75.78,the AUC was 0.705,the sensitivity was 0.648,and the specificity was 0.629.Conclusion: 1.The left ventricular flow field had changed in patients with mild left anterior descending coronary artery stenosis at rest.The formation of abnormal vortices in S1,D1,and D3 was observed.The EL in each phase increased,and the change of EL in the middle and apical segments were more significant.The compensatory increase of D1 ELb was helpful for the evaluation of mild coronary artery stenosis.2.After exercise,the left ventricular blood flow fields in the two groups were more disordered than the resting period.The EL of different segments in case group were generally reduced than the control group after exercise.The decrease in S3 ELm and S2 ELa-r after exercise would increase the risk of mild left anterior descending coronary artery stenosis.The increase of D1 vortex area after exercise was helpful for the evaluation of patients with mild coronary artery stenosis.3.Patients with mild left anterior descending coronary stenosis had lower left ventricular energy reserves than those without stenosis,and the changes in the apical segment were more sensitive.4.The combination of VFM and treadmill exercise stress echocardiography could further evaluate the changes in the left ventricular flow field in patients with mild coronary artery stenosis,which is expected to provide useful information about the assessment of coronary heart disease in an earlier stage. |
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