The Diagnostic Value Of Transthoracic Echocardiography In Detecting The Blood Flow Velocity Of The Left Anterior Descending Coronary Artery In Patients With Coronary Slow Flow

Objective:Coronary slow flow(CSF)refers to the phenomenon in which the coronary arteries are "normal" or "close to normal" confirmed by coronary angiography(CAG),but the end filling is delayed.Although the CAG results of CSF patients mostly indicate no obvious stenosis,nearly 80% of CSF patients have recurrent chest pain symptoms,which has received clinical attention.At present,the diagnosis of CSF depends on the number of TIMI frames(TFC)of CAG,but due to its invasiveness and high cost,repeated inspections are not suitable.Transthoracic echocardiography has the advantages of non-invasive,low cost,real-time and simple,and can evaluate the blood flow velocity of the left anterior descending coronary artery(LAD).However,the correlation between TFC and LAD blood flow velocity parameters is unclear.Therefore,The purpose of this study is to analyze the correlation between LAD blood flow velocity parameters and TFC using transthoracic echocardiography,and to obtain the best parameters that can diagnose CSF non-invasively and in real time,so as to clinically evaluate the efficacy and condition changes of CSF patients provide new methods.Method:Research object:Case group(CSF group): Choose the CAG confirmed epicardial coronary artery to be "normal" or "close to normal"(stenosis <40%),and at least one coronary artery blood flow correction TIMI frame number(c TFC)> 27 frames Of CSF patients;Control group(Con group): Selected patients whose epicardial coronary arteries were "normal" or "close to normal" confirmed by CAG during the same period and whose blood flow c TFC of 3 coronary arteries were all less than 27 frames of age and gender.Coronary angiography: The radial artery approach is selected for coronary angiography,and the Judkins technique is used for multi-position angiography.The blood flow velocity of coronary arteries adopts TIMI framing method.The frame number of the last frame minus the frame number of the first frame is the exact frame number of the coronary artery.Echocardiography: All patients underwent conventional transthoracic echocardiography(TTE)and two-dimensional speckle tracking imaging(2D-STE)within 48 hours after coronary angiography to detect left ventricular systolic and diastolic function.At the same time,the patients were examined by color Doppler in the middle and far segment of LAD,and the blood flow spectrum of the middle and far segment of LAD was obtained.Ultrasound parameters of left ventricular function:Left ventricular end diastolic diameter(LVEDD);Left ventricular end diastolic volume(LVEDV);Left ventricular ejection fraction(LVEF);Left atrium anteroposterior diameter(LADap);Left atrial volume index(LAVI);Early and late diastolic blood flow velocity(E and A)of the mitral valve,calculate E/A;TDI measures the early diastolic peak velocity(e’)of the free wall annulus of the mitral valve and calculates E/e’.LAD blood flow spectrum parameters:Peak flow velocity of the anterior descending branch(Vmax);The mean flow velocity of the anterior descending branch(Vmean);Peak anterior descending branch pressure(PDP);Mean anterior descending branch pressure(MDP);Anterior descending branch blood flow velocity time integral(VTI);Front descending spectrum envelope time(Env Ti);Anterior descending blood flow pulsatility index(PI);Anterior descending branch blood flow resistance index(RI);Results:1.Comparison of left ventricular function between the two groupsE/e’ and GLS in the CSF group were significantly lower than those in the Con group(P<0.05),suggesting that the left ventricular systolic and diastolic functions of CSF patients were reduced.2.Comparison of LAD coronary blood flow parameters between the two groupsThe TFC and average TFC of the three coronary arteries in the CSF group were higher than those in the control group(P<0.05).The blood flow velocity parameters Vmax,Vmean,PDP,MDP,VTI and PI of LAD detected by TTE in CSF group were significantly lower than those in Con group(P<0.05).The above suggests that the LAD blood flow velocity of CSF patients is lower than that of the control group.3.Correlation between LAD blood flow velocity parameters and TFCThe LAD blood flow velocity parameters except RI were negatively correlated with TFC(P<0.05).It is suggested that the greater the number of frames of coronary artery velocity in CSF patients,the smaller the blood flow parameters measured by TTE.4.LAD blood flow velocity parameter detection CSF efficiency evaluationROC curve analysis shows that the four parameters Vmax,Vmean,PDP,and MDP have the highest detection efficiency for CSF(area under the ROC curve:0.877,0.845,0.873,0.854).5.Subgroup analysis: CSF patients were divided into two groups according to whether the corrected TFC of the anterior descending branch was greater than 27 frames.(1)Correlation analysis of coronary artery blood flow parameters and LAD blood flow frames in the LAD blood flow velocity reduction group and the LAD blood flow velocity normal groupThe correlation of coronary artery blood flow parameters in patients with reduced LAD is better than that of patients with normal LAD.(2)Evaluation of the efficacy of CSF in the detection of coronary artery blood flow parameters in the LAD blood flow rate reduction groupThe AUC(respectively: 0.920,0.892,0.894,0.869),sensitivity(respectively:82.61%,71.01%,82.61%,95.65%)and specificity of each parameter of coronary artery blood flow measured by the patients in the LAD reduction group(Respectively: 83.33%,88.46%,80.77%,62.82%)are better than the normal LAD blood flow velocity group.It shows that the application of TTE to detect LAD blood flow velocity parameters is more suitable for patients in the LAD blood flow velocity reduction group.(3)Evaluate the effectiveness of CSF in detecting coronary artery blood flow parameters in patients with normal LAD blood flow velocityThe AUC(respectively: 0.609,0.611,0.576,0.566)of each parameter of coronary blood flow measured by TTE in the patients in the non-slow LAD group was greater than 50%,suggesting that the LAD blood flow parameter evaluation can also be applied to the CSF patients in the non-LAD group Coronary blood flow velocity,but the detection efficiency is low compared with the LAD blood flow velocity reduction group.Conclusion:1.The left ventricular diastolic and systolic functions of CSF patients are reduced;2.The coronary blood flow parameters of CSF patients were lower than those of the control group;3.Coronary artery blood flow parameters in CSF patients are significantly negatively correlated with the average coronary blood flow velocity;4.The detection efficiency of Vmax,Vmean,PDP and MDP in the coronary blood flow parameters of CSF patients is higher,and the LAD blood flow speed is reduced,and the detection efficiency is higher;5.TTE can detect coronary blood flow in patients with CSF in a noninvasive,real-time,and convenient way,providing a theoretical basis for clinical evaluation of CSF.