Assessment of left ventricular myocardial systolic acceleration in diabetic rats using velocity vector imaging

Evaluation of left ventricular myocardial movement in rats by velocity vector imaging

AIM

To use velocity vector imaging (VVI) technology to evaluate the correlation between the apical four-chamber view and short-axis myocardial movement in rats.

METHODS

We used 25 10-week-old male Sprague-Dawley rats to measure the myocardium peak systolic velocity (Vs; cm/s), peak diastolic velocity (Vd; cm/s), peak systolic strain (SR; %), peak systolic strain rate (SRs; 1/s), and peak diastolic strain rate (SRd; 1/s) from the apical four-chamber view of the left ventricle (LV) and the parasternal mitral valve (PMV)-level short-axis view, and to analyze the correlation between myocardial motion in corresponding views of the two sections.

RESULTS

Comparing the myocardial motion between the lateral wall's basal segment in the apical four-chamber view of the LV and the lateral wall of the PMV-level short-axis view revealed that the Vd was positively correlated (r = 0.59, p<0.01), as was SRs (r = 0.68, p<0.05). Comparing the myocardial motion between the lateral wall's middle segment in the apical four-chamber view of the LV and the lateral wall of the PMV-level short-axis view demonstrated that Vd, SRs, and SRd were positively correlated (r = 0.63, 0.82, 0.79, respectively, all p<0.01). Our comparison of myocardial motion between the posterior septum's basal segment in the apical four-chamber view of the LV and the posterior septum of PMV-level short-axis view showed that Vd and SRs were positively correlated (r = 0.57, 0.68, respectively, both p<0.01). Comparing the myocardial motion between the posterior septum's middle segment in the apical four-chamber view of the LV and the posterior septum of the PMV-level short-axis view revealed that Vs, Vd, SR, and SRd were positively correlated (r = 0.89, 0.63, 0.64, 0.6, respectively, all p<0.01), and the SRs also had a significant positive correlation (r = 0.53, p<0.05).

CONCLUSION

VVI technology could be a valuable tool for evaluating the myocardial walls motion of the apical four-chamber view of the rat LV.

Evaluation of the Effects of Schisandra chinensis on the Myocardium of Rats with Hyperthyroid Heart Disease by Using Velocity Vector Imaging Combined with the Estimation of p53 Expression and Calmodulin Activity

Schisandra chinensis (SC) is reported to improve myocardial ischemia. Velocity vector imaging (VVI) is a noninvasive technique for evaluating myocardial function in humans, while few reported on the application in animals. In this study, we aimed to evaluate the improved effects of SC on the myocardium of Sprague Dawley rats having hyperthyroid heart disease (HHD) using VVI technique. HHD models were established by injecting daily with subcutaneous levothyroxine (0.5 mg/kg). Then, the SC group was administered the aqueous extract of SC (2 g/kg) once daily, while the HHD and control (CON) groups were administered the same amount of distilled water daily. All the rats were provided the same amount of food and water daily, and the intervention was stopped after 28 days. The efficacy of SC in HHD rats was evaluated by ultrasound VVI. The serum total triiodothyronine level, total thyroxine level, N-terminal pro-brain natriuretic peptide expression, p53 expression, and calmodulin (CaM) activity were assessed by western blotting, Hematoxylin-Eosin and Masson staining, and electron microscopy. The results indicated that SC significantly improved the systolic velocity, diastolic velocity, strain, systolic strain rate, and diastolic strain rate of the heart by significantly reducing p53 expression and CaM activity (P < 0.05), improving myocardial fibrosis in HHD rats. Also, VVI can be a valuable tool for the evaluation of myocardial function in HHD rats.

Prevention of doxorubicin-induced cardiomyopathy using targeted MaFGF mediated by nanoparticles combined with ultrasound-targeted MB destruction

The present study seeks to observe the preventive effects of doxorubicin-induced cardiomyopathy (DOX-CM) in rats using targeted non-mitogenic acidic fibroblast growth factor (MaFGF) mediated by nanoparticles (NP) combined with ultrasound-targeted MB destruction (UTMD). DOX-CM rats were induced by intraperitoneally injected doxorubicin. Six weeks after intervention, the indices from the transthoracic echocardiography and velocity vector imaging showed that the left ventricular function in the MaFGF-loaded NP (MaFGF-NP) + UTMD group was significantly improved compared with the DOX-CM group. The increased malondialdehyde and decreased superoxide dismutase were observed in the DOX-CM group, while a significant increase in superoxide dismutase and a decrease in malondialdehyde were detected in the groups treated with MaFGF-NP + UTMD. From the Masson staining, the MaFGF-NP + UTMD group showed a significant difference from the DOX-CM group. The cardiac collagen volume fraction and the ratio of the perivascular collagen area to the luminal area number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling positive cells in the MaFGF-NP + UTMD group decreased to 8.9%, 0.55-fold, compared with the DOX-CM group (26.5%, 1.7-fold). From terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling staining, the results showed the strongest inhibition of apoptosis progress in MaFGF-NP + UTMD group. The immunohistochemical staining of the TGF-β1 in MaFGF-NP + UTMD group reached 3.6%, which was much lower than that of the DOX-CM group (12.6%). These results confirmed that the abnormalities, including left ventricular dysfunction, myocardial fibrosis, cardiomyocytes apoptosis and oxidative stress, could be suppressed by twice weekly MaFGF treatments for 6 consecutive weeks (free MaFGF or MaFGF-NP+/UTMD), with the strongest improvements observed in the MaFGF-NP + UTMD group. Western blot analyses of the heart tissue further revealed the highest pAkt levels, highest anti-apoptosis protein (Bcl-2) levels and strongest reduction in proapoptosis protein (Bax) levels in the MaFGF-NP + UTMD group. This study confirmed the preventive effects of DOX-CM in the rats with MaFGF-NP and UTMD by retarding myocardial fibrosis, inhibiting oxidative stress, and decreasing cardiomyocyte apoptosis.

Tissue Doppler imaging is a sensitive echocardiographic technique to detect subclinical systolic and diastolic dysfunction of both ventricles in type 1 diabetes mellitus

Background

Subclinical left (LV) and right ventricular (RV) dysfunction has been demonstrated in type 2 diabetes mellitus and evidence indicates impaired LV diastolic function in type 1 diabetes mellitus (T1DM) as well. The aim of our study was to evaluate the role of tissue Doppler imaging (TDI) in assessment of global LV and RV function in T1DM patients.

Methods

A detailed two-dimensional, pulsed wave Doppler and pulsed wave TDI analysis was performed in 53 normotensive middle-aged T1DM patients and compared to healthy controls.

Results

In T1DM patients TDI analysis revealed reduced mean mitral septal and lateral E’ velocities as well as reduced mean tricuspid E˙t velocity compared to healthy controls (E’sept 8.89 ± 1.89 cm/s vs. 11.50 ± 2.41 cm/s, p < 0.001; E’lat 12.29 ± 2.58 cm/s vs.15.30 ± 2.95 cm/s, p < 0,001; E’t 13.56 ± 2.91 cm/s vs. 15.60 ± 2.99 cm/s, p = 0.001). Mean ratios E/E’sept, E/E’lat and E/E’t were significantly higher in diabetics with cutoff value of 7.4 for E/E’sept and 3.4 for E/E’t, differentiating diabetics with LV and RV diastolic impairement from matched healthy controls (sensitivity 76.5 %, specificity 73.8 % for E/E’sept and sensitivity 72.1 %, specificity 66.7 % for E/E’t). Myocardial acceleration during isovolumetric contraction (IVA) measured at the septal mitral (LV IVA) and lateral tricuspid annulus (RV IVA) was the only parameter indicating reduced contractility of both ventricles in diabetics compared to controls (LV IVA 230.70 ± 61.26 cm/s² vs. 283.32 ± 59.74 cm/s², p < 0,001; RV IVA 275.48 ± 68.08 cm/s² vs. 316.86 ± 80.95 cm/s², p = 0.011). LV IVA had better diagnostic accuracy than RV IVA to predict early contractile impairement in T1DM patients (area under the curve 0.758, p < 0.001 for LV IVA and 0.648, p = 0.017 for RV IVA).

Conclusions

TDI is essential to detect subclinical diastolic deterioration of both ventricles in T1DM patients. TDI-derived IVA might be useful to assess early systolic alterations of both ventricles in T1DM patients.