Li Chunlei

Assessment of left ventricular longitudinal regional myocardial systolic function by strain imaging echocardiography in patients with hypertrophic cardiomyopathy.

SummaryTo assess the left ventricular longitudinal regional myocardial systolic function by strain imaging (SI) echocardiography and to study the relationship between regional myocardial systolic function and left ventricular structure in patients with hypertrophic cardiomyopathy (HCM). SI echocardiography were performed in 18 patients with HCM and 17 healthy subjects. For each wall, regional myocardial systolic strain was analyzed at the basal, mid, and apical level respectively. And the peak systolic strain was measured. Our results showed that the patients with HCM had reduced peak systolic strain at almost each segment of different walls when compared with healthy subjects. There was significant correlation between the mid-septum peak systolic strain and the thickness of IVS, so was the correlation between the mid-septum peak systolic strain and the IVS to LVPW thickness ratio. This study demonstrated that the left ventricular longitudinal regional myocardial systolic function was abnormal in HCM, and this kind of abnormalities existed extensively in hypertrophic and non-hypertrophic cardiac segments. The degrees of left ventricle hypertrophy and asymmetry are related to the myocardial regional systolic function in HCM.To assess the left ventricular longitudinal regional myocardial systolic function by strain imaging (SI) echocardiography and to study the relationship between regional myocardial systolic function and left ventricular structure in patients with hypertrophic cardiomyopathy (HCM). SI echocardiography were performed in 18 patients with HCM and 17 healthy subjects. For each wall, regional myocardial systolic strain was analyzed at the basal, mid, and apical level respectively. And the peak systolic strain was measured. Our results showed that the patients with HCM had reduced peak systolic strain at almost each segment of different walls when compared with healthy subjects. There was significant correlation between the mid-septum peak systolic strain and the thickness of IVS, so was the correlation between the mid-septum peak systolic strain and the IVS to LVPW thickness ratio. This study demonstrated that the left ventricular longitudinal regional myocardial systolic function was abnormal in HCM, and this kind of abnormalities existed extensively in hypertrophic and non-hypertrophic cardiac segments. The degrees of left ventricle hypertrophy and asymmetry are related to the myocardial regional systolic function in HCM.

Detection of left ventricular regional relaxation abnormalities in patients with hypertrophic cardiomyopathy by quantitative tissue velocity imaging

SummaryTo assess the left ventricular regional relaxation abnormalities in patients with hypertrophic cardiomyopathy (HCM) by quantitative tissue velocity imaging (QTVI), Doppler echocardiography and QTVI were performed in HCM (n=10) and healthy subjects (n=11) at apical longaxis, two-chamber and four-chamber views. Regional early diastolic velocity (rVe) and regional atrial contraction (rVa) were measured at each segment of ventricular middle, basal and annular levels. Mean rVe and mean rVa at three levels as well as mean rVe/rVa ratio were calculated. Our results showed that transmitral inflow peak velocities during early diastole (E) and atrial contraction (A) were also measured and E/A ratio was calculated. The rVe of all left ventricular segments in HCM were lower than those in healthy subjects (P<0.05), but compared with healthy subjects majority of rVa in HCM were not different except inferior wall and anterior wall. E between HCM and healthy subjects was different (P=0.036), while mean rVe between them was significantly different (P<0.0001). Mean rVa and mean rVe/rVa of three levels were lower in HCM than in healthy subjects (P=0.05), but there were no differences in A and E/A between them (P=0.22,P=0.101). Left ventricular regional myocardial relaxation is reduced in HCM. Transmitral inflow E and A are influenced by preload, relaxation of myocardium and atrial contraction, etc., while rVe and rVa reflect myocardial relaxation function independently. QTVI is more sensitive and more accurate than conventional Doppler imaging for characterizingregional diastolic properties in HCM.

Assessment of effect of angiotensin II receptor antagonist losartan on aortic distensibility in patients with essential hypertension by echocardiography.

SummaryThe effects of angiotensin II receptor antagonist losartan on elastic properties of aorta in patients with mild to moderate essential hypertension were assessed. The ascending aortic distensibility in 26 patients (48±3 years) with mild to moderate essential hypertension before and after 12 weeks of treatment with losartan (50 mg/day) was evaluated by using two-dimensional echocardiography. M-mode measurements of aortic systolic (D5) and diastolic diameter (Dd) were taken at a level approximately 3 cm above the aortic valve. Simultaneously, cuff brachial artery systolic (SBP) and diastolic (DBP) pressures were measured. Aortic pressure-strain elastic modulus (Ep) was calculated as Dd×(SBP−DBP)/(Ds−Dd)×1333 and stiffness index beta (β) was defined as Dd×Ln (SBP/DBP)/(Ds−Dd). Blood pressure significantly decreased from 148±13/95±9 mmHg to 138±12/88±8 mmHg (systolic blood pressure,P=0.001; diastolic blood pressure,P=0.003). There was no significant difference in pulse pressure before and after treatment with losartan (53±10 mmHg vs 50±7 mmHg). The distensibility of ascending aorta increased significantly as showed by the significant decrease in pressure-strain elastic modulus from 4.42±5.79×106 dynes/cm2 to 1.99 ±1.49×106 dynes/cm2 (P=0.02) and stiffness index beta from 27.4±32.9 to 13.3±9.9 (P=0.02). Although there was a weak correlation between the percent changes in pressure-strain elastic modulus and stiffness index beta and that in diastolic blood pressure after losartan treatment (r=0. 40,P=0.04 andr=0.55,P=0.004, respectively), no correlation was found between the percent changes in pressure-strain elastic modulus and stiffness index beta and that in systolic blood pressure (r=0.04,P=0.8 andr=0.24,P=0.2, respectively). Our study demonstrated that angiotensin II receptor antagonist losartan has a beneficial effect on aortic distensibility in patients with mild to moderate essential hypertension and this effect is partly independent of blood pressure reduction.

Influence of contractility on myocardial ultrasonic integrated backscatter and cyclic variation in integrated backscatter

SummaryTo evaluate the effects of left ventricular contractility on the changes of average image intensity (AII) of the myocardial integrated backscatter (IB) and cyclic variation in IB (CVIB), 7 adult mongrel dogs were studied. The magnitude of AII and CVIB were measured from myocardial IB carves before and after dobutamine or propranolol infusion. Dobutamine or propranolol did not affect the magnitude of AII (13.8±0.7 vs 14.7±0.5,P>0.05 or 14.3±0.5 vs 14.2±0.4,P>0.05). However, dobutamine produced a significant increase in the magnitude of CVIB (6.8±0.3 vs 9.5±0.6,P<0.001) and propranolol induced significant decrease in the magnitude of CVIB (7.1±0.2 vs 5.2±0.3,P<0.001). The changes of the magnitude of AII and CVIB in the myocardium have been demonstrated to reflect different myocardial physiological and pathological changes respectively. The alteration of contractility did not affect the magnitude of AII but induced significant change in CVIB. The increase of left ventricular contractility resulted in a significant rise of the magnitude of CVIB and the decrease of left ventricular contractility resulted in a significant fall of the magnitude of CVIB.

Evaluation of normal fetal left cardiac function by tissue Doppler imaging.

SummaryTo explore the feasibility of using tissue Doppler imaging technique for the evaluation of fetuss left ventricular diastolic function, and to confirm its reliability by comparing it with traditional methods, this study examined 61 pregnant women in whom satisfactory images were obtained of fetal echocardiography. The peak velocity of blood stream were measured, including E, A and E/A at mitral valve orifice on the four chamber view with pulse wave. And then tissue Doppler imaging mode was employed to measure the velocity of mitral valve annulus including Ea, Aa, Sa and Ea/Aa. Correlation analysis was conducted between the velocity of orifice and that of annulus in terms of gestation age. And then correlation analysis was performed between above data and gestation ages. A positive correlation was found between the velocity of orifice and that of annulus, and the velocity increased with the gestation age. The change was the most significant between the 28th and the 34th week of gestation age. Our study showed that it is feasible to evaluate the fetuss left ventricular diastole function by tissue Doppler imaging. Its stability can avoid the influence of fetal heart rates and preload.

Value of echocardiography for evaluation of the flow-dependent epicardial coronary vasodilation in vivo.

SummaryTo assess the value of echocardiography for detection of the flow-dependent epicardial coronary vasodilation, the changes in internal diameter of the left anterior descending coronary arteries (LAD) induced by reactive hyperemia were studied by echocardiography in 12 health anesthetized open-chest dogs. Reactive hyperemia was induced by brief occlusion of the left anterior descending coronary artery for 30 s followed by rapid release. The two- dimensional images of the left anterior descending coronary artery before and after reactive hyperemia with and without intracoronary infusion of NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS) were investigated. The internal diameter of LAD was measured and its percent change induced by reactive hyperemia was calculated. Our results showed that the internal diameter of LAD was 2.23±0.19 mm before intracoronary infusion of L-NAME (baseline). The internal diameter of LAD significantly increased to 2.52±0.24 mm (P<0.01) after reactive hyperemia at baseline, and the percent change in internal diameter of LAD was (13.10±3.59)%. The internal diameter of LAD before and after reactive hyperemia under the condition of intracoronary infusion of L-NAME was not different from that before reactive hyperemia at baseline. The percent change in internal diameter of LAD was (1.07±2.97)%, and it was significantly lower than that at baseline (P<0.001). We are led to conclude that the change in internal diameter of LAD responding to reactive hyperemia was detected sensitively by echocardiography, and this change was associated with endothelium-derived nitric oxide.

Nitric Oxide Formation Contributes to β-adrenergic Dilation of Epicardial Coronary Arteries in Response to Intravenous Administration of Dobutamine in Dogs

SummaryTo examine the role of nitric oxide in the β-adrenergic vasodilation of epicardial coronary arteries in dogs, 12 dogs were instrumented for measurement of left anterior descending coronary artery diameter by transthoracic echocardiography before and after dobutamine (5 μg/kg/min IV) with and without intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA) (1 mg/kg). In all 12 dogs, the diameter of left anterior descending coronary artery increased significantly from 2. 35±0.25 mm to 2.59±0.24 mm (P<0.001) after dobutamine administration. In 6 of the 12 dogs, the percent change in left anterior descending coronary artery diameter induced by dobutamine decreased significantly from 12.5%±8.6% to −1.5%±5.4% (P<0.05) after the administration of intracoronary L-NMMA (1 mg/kg for 5 min) to block nitric oxide synthesis from L-arginine. The study demonstrated that nitric oxide formation contributes to the β-adrenergic dilatory response of epicardial coronary arteries to dobutamine in dogs.

Effect of pressure on intracardiac backscatter from microbubbles.

SummaryThe backscatter from sonicated albumin microbubbles (Albunex) was analyzed using acoustic densitometry in anin vitro pulsatile heart model to evaluate the effects of pressure on the backscatter from Albunex, and the cardiac cyclic changes of intracardiac backscatter from sonicated albumin microbubbles in 16 healthy persons were analyzed. It was found that the Albunex microbubbles were compressed in systole and decompressed in diastole, causing corresponding changes of backscatter in cardiac cycle. Although the intensities of backscatter in diastole and systole were related to the concentration of microbubbles, the concentration of microbubbles had no effect on the difference of end-diastolic and end-systolic backscatter. The difference of the backscatter was highly correlated with end-systolic pressure (r=0.96,P = 0.001). In human studies, we also observed same intracardiac cyclic changes of backscatter from sonicated albumin microbubbles. Our study indicates that it is possible to evaluate the intracardiac pressure non-invasively by analyzing the intracardiac backscatter from the microbubbles with acoustic densitometry.