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To 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.

The 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±5.79×106dynes/cm2to 1.99 ±1.49×106dynes/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.

To study reliability and reliable indices of quantitative assessment of right ventricular systolic function by time-intensity curve (TIC) with right ventricular contrast, 5% sonicated human albumin was injected intravenously at a does of 0.08 ml/kg into 10 dogs at baseline status and cardiac insufficiency. Apical four-chamber view was observed for washin and washout of contrast agent from right ventricle. The parameters of TIC were obtained by curve fitting. The differences of parameters were analyzed in different states of cardiac functions. Among the parameters derived from TIC, the time constant (k) was decreased significantly with decline of cardiac function (P<0.001). But half-time of decent of peak intensity (HT) and mean-transit-time (MTT) of washout were increased significantly (P<0.001). The k was strongly related to cardiac output of right ventricle (CO) and ejection fraction (EF) of left ventricle and fractional shortening (FS) of left ventricle. Right ventricular systolic function could be assessed reliably by the parameters derived from TIC with right ventricular contrast echocardiography. The k, HT and MTT are reliable indices for quantitative assessment of right ventricular systolic function.

To 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.

Summary: The 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.

The backscatter from sonicated albumin microbubbles (Albunex) was analyzed using acoustic densitometry in anin vitropulsatile 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.

Summary: To investigate the relationship between endothelial function and carotid artery wall thickening in patients with early mild essential hypertension, the percent dilatation of humerus diameter and intimal-medial thickening (IMT) of common carotid artery was measured by using high-resolution ultrasound in 20 patients with early mild essential hypertension and 18 patients with normotension. The patients with hypertension had not been treated and their history of increased blood pressure was less than 12 months. In essential hypertension group, the percent dilatation of humerus diameter decreased significantly (2. 65 ±0. 98 % vs 6. 38 ±1. 61 %); IMT of carotid artery increased (0. 88 ±0. 16mm vs 0. 58± 0. 08). There was significant negative correlation between IMT and the percent dilatation of humerus diameter (γ= −0. 82,P<0. 05), and no correlation between IMT and 24 h mean systolic, diastolic pressure (γ= 0. 12 and γ= 0. 07, respectively;P>0. 05). Our results suggested that there was endothelial dysfunction in early mild essential hypertension. Endothelial dysfunction may not only contribute to the pathogenesis of hypertension but also serve as the most important inducing factor leading transformation from hypertension to atherosclerosis.

To investigate the relationship between endothelial function and carotid artery wall thickening in patients with early mild essential hypertension, the percent dilatation of humerus diameter and intimal-medial thickening (IMT) of common carotid artery was measured by using high-resolution ultrasound in 20 patients with early mild essential hypertension and 18 patients with normotension. The patients with hypertension had not been treated and their history of increased blood pressure was less than 12 months. In essential hypertension group, the percent dilatation of humerus diameter decreased significantly (2. 65 ±0. 98 % vs 6. 38 ±1. 61 %); IMT of carotid artery increased (0. 88 ±0. 16mm vs 0. 58± 0. 08). There was significant negative correlation between IMT and the percent dilatation of humerus diameter (γ= −0. 82,P<0. 05), and no correlation between IMT and 24 h mean systolic, diastolic pressure (γ= 0. 12 and γ= 0. 07, respectively;P>0. 05). Our results suggested that there was endothelial dysfunction in early mild essential hypertension. Endothelial dysfunction may not only contribute to the pathogenesis of hypertension but also serve as the most important inducing factor leading transformation from hypertension to atherosclerosis.

To 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.