| Echocardiography has been focused on detecting left ventricular (LV) function in the study of heart for a long time, but not as much on left atrial (LA) function. In recent years, with the development of cardiac research, more and more attention focused on LA function. LA function plays an important role in maintaining LV function.In many physiological or pathological conditions, especially in the setting of LV diastolic dysfunction, left atrium adjusts altered LV filling pressures and keeps normal cardiac stroke volume by LA function. In many cardiovascular diseases, such as hypertension, coronary heart disease, hypertrophic cardiomyopathy, dilated cardiomyopathy, etc, the structure and function of left atium have remodeled and changed before the left ventricle. Therefore, the utility of LA function for monitoring cardiovascular risk and for guiding therapy is an evolving science and it could represent a useful tool to quantify risk patients and evaluate prognosis.The purpose of this study was to explore left atrial function quantitatively by echocardiography in patients with coronary artery disease or myocardial disease, and monitor the changes of LA function in order to early detect the change of cardiac function and provide important clinical information.Part 1 Evaluation of left atrial function in patients with coronary artery disease by echocardiography(1) Evaluation of the effect of coronary artery disease on left atrial function by echocardiographyObjective To assess the effect of coronary artery disease (CAD) on left atrial function by echocardiography. Methods There were 25 patients with CAD and 25 controls in this study. Left atrial diameter (LAD), left ventricular diameter (LVD) were measured by M-mode in parastermal long-axis view. Transmitral flow velocities were obtained by pulsed-wave Doppler echocardiography, positioning a sample volume at a mitral tip level in an apical four-chamber view. Mitral flow parameters including peak velocities during early diastole (E) and late diastole (A) were measured, and the E/A ratio was calculated. Left ventricular ejection fraction (LVEF) was measured with Simpson's method on the two-and four-chamber views. Strain rate (SR) imaging was performed on all cases. Peak SR was measured at each segment (septal, lateral, posterior, anterior, and inferior walls) and mean peak systolic SR (SRs), peak early diastolic SR (SRe) and peak atrial systolic SR (SRa) were calculated by averaging the data in each segment.Results Compared with controls, LAD of CAD were increased (P<0.05); the value of E and the E/A ratio turned lower, the value of A was increased (P<0.05); LVD and LVEF had no significant changes (P>0.05); SRs and SRe of CAD were significantly lower (P<0.05), SRa was increased (P<0.05).Conclusions Because of myocardial ischemia, left ventricular regional function changed, which influenced the left atrial function of patients with CAD. The changes of left atrial function presented as reservoir and conduit functions decreased, and pump function increased.(2) Evaluation of the effect of coronary artery bypass grafting on left atrial function by echocardiographyObjective To explore the effect of coronary artery bypass grafting (CABG) on left atrial function by echocardiography. Methods The study included 23 patients with coronary heart disease who underwent coronary artery bypass grafting in our hospital, and the purpose is to assess left atrial function by echocardiography. Left atrial cycle volumes were measured by the Simpson's method. Left atrial volumes were measured at the point of mitral valve closure (minimal, LAVmin), onset of atrial systole (P wave of the simultaneously recorded electrocardiogram, LAVp), and at the point of mitral valve opening (maximal, LAVmax) from the apical four- and two-chamber views. Left atrial active emptying fraction (LAAEF) and left atrial passive emptying fraction (LAPEF) were calculated. Left ventricular ejection fraction (LVEF) was measured with Simpson's method on the two- and four-chamber views. SR imaging was performed on those patients to evaluate left atrial function quantitatively at baseline (before CABG), and at 1 week,1 month and 3 months after CABG. Peak SR was measured at each segment (septal, lateral, posterior, anterior, and inferior walls) and mean peak systolic SR (SRs), peak early diastolic SR (SRe) and peak atrial systolic SR (SRa) were calculated by averaging the data in each segment.Results Compared with the baseline, LAVp, LAVmax, LAVmin, LAAEF and LAPEF had on significant differences at 1 week (P>0.05). LAVp, LAVmin, LAVmax and LAAEF decreased gradually after CABG, LAPEF increased gradually after CABG (P<0.05). Compared with the baseline, the peaks of SR curve showed no significant differences at 1 week (P>0.05). Nevertheless, the peaks of SR were increased at systole and early diastole, decreased at atrial contraction at 1 month (P<0.05). Those changes were turned more significantly at 3 months (P<0.01). Left ventricular ejection fraction (LVEF) both increased at 1 month and 3 months, and its changing rate correlated inversely with the changing rate of SRa respectively (r=-0.751,-0.783; P<0.01,0.01).Conclusions Left atrial function was affected by CABG. Echocardiography could evaluate the atrial function quantitatively and monitor the changing of left atrial function dynamically after CABG. Part 2 Evaluation of left atrial function in patients with myocardial disease by echocardiography(1) Evaluation of left atrial function in patients with hypertrophic cardiomyopathy by echocardiographyObjective To assess the value of echocardiography in detecting left atrial function in patients with hypertrophic cardiomyopathy (HCM).Methods Thirty-six patients with HCM were divided into two groups according to the pressure gradients of left ventricular outflow tract:the group of obstructive hypertrophic cardiomyopathy (OHCM) and the group of nonobstructive hypertrophic cardiomyopathy (NHCM). The following parameters were measured by M-mode in parasternal long-axis view:left atrial dimension in end systole, intraventricular and posterior wall thickness in end diastole. Transmitral flow velocities were obtained by pulsed-wave Doppler echocardiography, positioning a sample volume at a mitral tip level in an apical four-chamber view. Mitral flow parameters including peak velocities during early diastole (E) and late diastole (A) were measured, and the E/A ratio was calculated. Left ventricular ejection fraction (LVEF) was measured with Simpson's method on the two- and four-chamber views. Tissue velocity imaging of all patients and controls were accepted in apical two, four and long axis chamber views. Strain rate (SR) imaging was performed on those patients and controls. Peak SR was measured at each segment (septal, lateral, posterior, anterior, and inferior walls of left atrium, interventricular septum) and mean peak systolic left atrial SR (mLASRs), mean peak early diastolic left atrial SR (mLASRe), mean peak atrial systolic left atrial SR (mLASRa) and mean peak early diastolic left ventricular SR (mLVSRe) were calculated by averaging the data in all segments. Results mLASRs, mLASRe and mLVSRe of OHCM and NHCM were significantly lower than those of controls, while mLASRa of OHCM and NHCM were significantly higher than those of controls (P<0.05). Moreover, compared with NHCM, mLASRs, mLASRe and mLVSRe of OHCM were significantly lower, mLASRa of OHCM was significantly higher. mLASRa correlated inversely with mLVSRe of OHCM and NHCM respectively (r=-0.67,-0.75; P<0.01,0.01).Conclusions The change of left atrial function of HCM presented as reservoir and conduit functions decreased and pump function increased. Those changes of OHCM were more significantly than NHCM. Echocardiography could evaluate the left atrial function and provide important clinical information.(2) Evaluation of left atrial function in patients with dilated cardiomyopathy by echocardiographyObjective To evaluate left atrial function in patients with dilated cardiomyopathy (DCM) by echocardiography.Methods There were 31 patients with DCM and 30 controls in this study. Left atrial diameter (LAD), left ventricular diameter (LVD) were measured by M-mode in parasternal long-axis view. Transmitral flow velocities were obtained by pulsed-wave Doppler echocardiography, positioning a sample volume at a mitral tip level in an apical four-chamber view. Mitral flow parameters including peak velocities during early diastole (E) and late diastole (A) were measured, and the E/A ratio was calculated. Left ventricular ejection fraction (LVEF) was measured with Simpson's method on the two-and four-chamber views. Strain rate (SR) imaging was performed on all cases. Peak SR was measured at each segment (septa], lateral, posterior, anterior, and inferior walls) and mean peak systolic left atrial SR (mLASRs), mean peak early diastolic left atrial SR (mLASRe) and mean peak atrial systolic left atrial SR (mLASRa) were calculated by averaging the data in all segments.Results Compared with controls, LAD and LVD were significantly increased (P< 0.01), the E/A ratio had no significant changes (P>0.05). LVEF and left atrial fractional shortening (LAFS) turned lower, mLASRs, mLASRe, and mLASRa of DCM all decreased significantly (P<0.05). mLASRa of DCM correlated positively with LAFS(r=0.79; P<0.01).Conclusions The left atrial function of DCM all decreased, including the reservoir, conduit and pump function. Echocardiography could evaluate the left atrial function of DCM quantitatively.
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