Search

Troglitazone, an oral antidiabetic agent, has hypoglycemic effects in insulin-resistant animal models and humans. This study was conducted to evaluate its effect on left ventricular diastolic dynamics of a spontaneous [...]

Recent in-vitro studies demonstrated that dihydropyridine calcium channel blockers have direct mineralocorticoid receptor antagonistic activity. The present study was conducted to examine the effects of a dihydropyridine calcium channel blocker, azelnidipine, on aldosterone-induced oxidative stress and renal injury.

We investigated the contribution of reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase-dependent reactive oxygen species (ROS) generation to the pathogenesis of diastolic heart failure (DHF) in Dahl salt-sensitive (DS) hypertensive rats, with the aim of testing our hypothesis that the cardioprotective effects of angiotensin II (Ang II) blockade are provided by the suppression of this pathway.

Mechanical forces and angiotensin II influence the structure and function of vascular cells, and play an important role in reactive oxygen species production. In this study, we examined the effects of mechanical stretch and angiotensin II on the expression of p22-phox and Nox-1, essential membrane components of NADPH oxidase, and superoxide production in rat vascular smooth muscle cells (VSMCs).

In myocardial contrast echocardiography (MCE), power Doppler imaging is more sensitive to contrast agent (microbubble) than gray-scale B-mode imaging; however, no data exist regarding the optimal contrast dose in power Doppler imaging. This study examined the optimal dose of contrast agent for power Doppler in assessing coronary stenosis.

Masugata H, Peters B, Lafitte S, et al. Comparison of open- and closed-chest canine model for quantification of coronary stenosis severity by myocardial contrast echocardiography. Invest Radiol 2003;3844–50.

This study investigated the effect of pioglitazone, an insulin sensitizer, on metabolic abnormalities and oxidative stress as a cause of myocardial collagen accumulation in prediabetic rat hearts. Twenty male diabetic rats and 9 male nondiabetic age-matched rats were used. The diabetic rats were divided into two groups diabetic treated and untreated. Pioglitazone was mixed in rat chow fed to the diabetic treated group (0.01). Treatment duration was 5 weeks. At baseline (15 weeks) and 20 weeks of age, blood glucose, lipid, insulin, and plasma malondialdehyde-thiobarbituric acid (MDA) levels were measured and Doppler echocardiography was tracked. At 20 weeks of age, left ventricular collagen content was studied. Blood glucose, plasma insulin, and triglyceride levels in the diabetic treated group were significantly lower than those in the untreated diabetic group. Deceleration time (ms) of early diastolic inflow in the treated diabetic group decreased significantly compared with the untreated diabetic group (65 ± 8 vs. 77 ± 8, p < 0.01). Ratio of left ventricular weight to body weight (mg/g) and ratio of left ventricular collagen content to dry weight (mg/100 mg) were decreased in the treated diabetic group (1.5 ± 0.1, 1.3 ± 0.3) compared with the untreated diabetic group (1.7 ± 0.2, p < 0.01; 1.7 ± 0.3, p < 0.05). Plasma MDA concentration (nmol/ml) significantly decreased (2.9 ± 0.3 at baseline to 2.3 ± 0.3 at 20 weeks, p 0.001) in the treated diabetic group, and was lower than that in the untreated diabetic group (3.2 ± 0.7 at 20 weeks, p < 0.05). Pioglitazone improved glucose and lipid metabolism and reduced oxidative stress in the left ventricle, which decreased left ventricular collagen accumulation and improved left ventricular diastolic function of prediabetic rat hearts.

Controversy exists regarding the influence of mitral regurgitation (MR) on thromboembolic risk in patients with atrial fibrillation. We aimed to investigate retrospectively a reduction of risk for stroke due to MR in atrial fibrillation and to evaluate the effectiveness of low-intensity anticoagulation therapy. In 313 patients with atrial fibrillation, transthoracic echocardiography was performed and MR was graded. Between the groups with no or mild MR (n 209) and with moderate or severe MR (n 104), age, sex, treatment, history of diabetes, hypertension, hyperlipemia and mitral stenosis, and previous stroke were compared. No significant differences in clinical characteristics, treatment, or history were observed between the two groups. The incidence of thromboembolism was significantly higher in the group with no MR (48 patients 23) than in the group with MR (14 patients 13, p < 0.05). In the MR group, previous stroke was frequently observed in patients without warfarin treatment (11 of 51 patients) compared with patients with low-dose warfarin treatment (international normalized ratio of 1.6–1.8) (3 of 53 patients, p < 0.05). Consequently, the thromboembolic event was markedly prevented by low-dose warfarin treatment.

OBJECTIVES

OBJECTIVES

Objectives.The purpose of the present study was to evaluate the feasibility of diagnosing vasospastic angina based on coronary artery tone as assessed by M-mode echocardiographic measurement of the dilation response of the left main coronary artery to nitroglycerin.

Background. Dynamic changes of myocardial blood flow have been observed after reperfusion of an occluded coronary artery. MCE performed by intracoronary contrast injection can provide an estimate of microvascular flow. We hypothesized that MCE performed using intravenous infusion of a new generation contrast agent and electrocardiogram-gated harmonic imaging would be able to assess serial changes of microvascular perfusion.

The long‐term effect of mexiletine on left ventricular (LV) contractility in patients with congestive heart failure is not clear. The authors therefore measured LV contractility before and after continuous oral administration of mexiletine in patients with congestive heart failure accompanied by mitral regurgitation (MR) using Doppler echocardiography. The study population consisted of 8 patients with congestive heart failure (6 due to dilated cardiomyopathy and 2 due to old myocardial infarction) accompanied by significant functional MR who had more than 1000 ventricular premature contractions (VPCs) per day or Class IV Lown classification arrhythmias before mexiletine administration. The LV contractility was evaluated by calculating a Doppler‐derived index, the rate of increase in LV pressure during the isovolumic contraction time (ICT ΔP/Δt), which has been confirmed to be nearly equal to LV Max dP/dt. The increase in LV pressure (ΔP) between 1 and 3 m/sec of the MR flow velocity as measured by continuous‐wave Doppler echocardiography was calculated using the simplified Bernoulli's equation, and ICT ΔP/Δt was derived by dividing ΔP by the time required for this change. The left ventricular ejection fraction and the left ventricular and left atrial dimensions also were measured by echocardiography. These parameters were obtained before and after 2 to 4 weeks of daily oral administration of mexiletine 300 mg. Values of ICT ΔP/Δt were 640 ± 202 mm Hg/sec and 650 ± 210 mm Hg/sec before and after mexiletine administration, respectively, showing no change. The left ventricular ejection fraction and the left ventricular and left atrial dimensions also were unchanged. These findings indicate that continuous oral administration of mexiletine has no effect on LV contractility in patients with congestive heart failure.