Evaluation Of The Effect Of Blood Pressure Changes On Myocardial Work In Hypertensive Patients By Echocardiography

Background:Left ventricular ejection fraction(LVEF)is still the most effective and widely used index for assessing left ventricular systolic function.It is difficult to identify early subclinical and local myocardial dysfunction,as it is calculated based on ventricular volume changes.Left ventricular strain can not only reflect the myocardial function of each segment but also be more sensitive to the detection of early subclinical myocardial dysfunction.Global longitudinal strain(GLS)has been recommended as a routine tool for the assessment of left ventricular systolic function by the American Society of Echocardiography and the European Society of Cardiovascular Imaging.At present,the main limitation of GLS is the dependence on afterload.The increase in afterload could reduce left ventricular strain,which led to a misunderstanding.In hypertensive patients with markedly fluctuating blood pressure,GLS appears to make it difficult to distinguish between true myocardial dysfunction and associated changes due to altered afterload.Myocardial work(MW)measured by echocardiography is a new method to evaluate myocardial function based on myocardial strain.MW combines deformation and hemodynamics by integrating GLS and systolic blood pressure,which is theoretically less affected by load.At present,it is not clear about the effect of blood pressure changes on myocardial work indices.Objective:1.To compare the differences in MW indices between healthy people and hypertensive patients;2.To explore the difference in the effect of blood pressure changes on MW indices in healthy people and hypertensive patients.Methods:A total of 117 subjects(34 healthy subjects and 83 hypertensive patients).Patients with hypertension were divided into Grade 1 hypertension(140-159/90-99 mmHg)and Grade 2 hypertension(≥160/100 mmHg)according to the 2020 International Hypertension Society of Hypertension and Global Hypertension Practice Guidelines.All subjects underwent echocardiographic measurements at rest,twice a day.Simultaneously,the brachial blood pressure was also measured.Images are saved in DICOM format and analyzed offline on the EchoPAC workstation to measure the structure and function of the left ventricle.Left ventricular pressure-strain loop(LV-PSL)was used to calculate global work index(GWI),global constructive work(GCW),global wasted work(GWW),and global work efficiency(GWE).The differences in the GLS and MW indices between the groups were compared,and the correlation of blood pressure changes with the changes in GLS and MW indices were evaluated.Results:Compared to the control group,the hypertensive group showed higher GWI,GCW,and GWW but lower absolute GLS and GWE(P<0.05).Absolute changes in blood pressure,GLS,and MW indices in hypertensive patients were significantly higher than that of the healthy control subjects(P<0.05).In healthy control group,with the increase in systolic blood pressure,GCW increased significantly(P<0.05),but GWI,GWW,GWE,and GLS did not change significantly(P>0.05).In hypertensive patients,with the increase in systolic blood pressure,GWI,GCW,and GWW increased(P<0.05),while GWE and absolute GLS decreased(P<0.05).Blood pressure changes had a significant correlation with changes in GLS and MW indices(P<0.05).Conclusion:1.Compared with healthy controls,GWI,GCW,and GWW were higher,while the absolute values of GLS and GWE were lower in hypertensive patients,suggesting that blood pressure affected myocardial deformation and work.2.In the healthy controls,the blood pressure fluctuation only caused the change of GCW,suggesting that the MW indices in the healthy population were relatively insusceptible to oscillations within the physiological range of blood pressure.3.In hypertensive patients,a significant increment in blood pressure caused an increase in GWI and GCW to preserve left ventricular systolic function.In addition,because the increased GCW did not balance the elevated GWW,the measured value of GWE decreased although it was in the normal range.Although the MW indices were still affected by the afterload,the difference between the MW indices provided more information than the decrease in GLS with an increase in afterload.This study suggests that it is necessary to reevaluate the values of GLS and MW in hypertensive patients with large blood pressure fluctuations.