Integrated backscatter during harmonic and fundamental frequency imaging--effect of depth, mechanical index, and tissue anisotropy: implications for myocardial tissue characterization

Electroacupuncture pretreatment promotes angiogenesis via hypoxia-inducible factor 1α and vascular endothelial growth factor in a rat model of chronic myocardial ischemia

OBJECTIVE

Electroacupuncture (EA) pretreatment appears useful in the treatment of chronic myocardial ischemia (CMI). The goal of this study was to investigate the effect of EA preconditioning on the regulation of hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) proteins in a CMI model of vascular regeneration.

METHODS

A CMI model was established by subcutaneous injection of isoprinosine hydrochloride (ISO) for 14 days in 45 Wistar rats, which had been randomly divided into a model group (n = 15), a CMI group pretreated with sham EA for 21 days (CMI + Sham group, n = 15) and a CMI group pretreated with verum EA for 21 days (CMI + EA, n = 15) prior to modeling. An additional 15 Wistar rats received 0.9% sodium chloride via intraperitoneal injection for 14 consecutive days (control group). Serum levels of VEGF and HIF-1α were measured by ELISA, while protein expression of VEGF and HIF-1α in the area of myocardial infarction was measured by Western blotting. The area of myocardial infarction and fibrosis of the myocardial tissue in the study groups were visualized by hematoxylin-eosin (HE) staining and Masson staining, respectively.

RESULTS

EA pretreatment improved cardiac function by regulating left ventricular end-diastolic diameter and left ventricular end-systolic diameter, left ventricular ejection fraction and the ST segment voltage of the electrocardiogram. EA pretreatment promoted vascular regeneration by increasing serum levels of VEGF and HIF-1α and by increasing protein expression of HIF-1α and VEGF in the infarcted region of the myocardium, leading to a reduction in the area of myocardial infarction on HE staining and reduction of myocardial fibrosis on Masson staining.

CONCLUSION

EA pretreatment promotes protein expression of HIF-1α and VEGF in areas of ischemic myocardium, which may represent useful biomarkers for coronary collateral establishment and offer potential targets for therapeutic angiogenesis in patients with CMI.

Non-invasive quantitation of myocardial fibrosis using combined tissue harmonic imaging and integrated backscatter analysis in dilated cardiomyopathy

BACKGROUND

Echocardiographic modalities have challenged the myocardial tissue characterization, but this reliability has not reached to the clinical use. This study investigated whether combined tissue harmonic imaging (THI) and integrated backscatter analysis (IB) provide the reliable and quantitative information about myocardial fibrosis in idiopathic dilated cardiomyopathy (DCM) in comparison with myocardial biopsy findings.

METHODS

We studied 56 patients with DCM. All patients underwent left ventricular endomyocardial biopsy and IB with fundamental imaging (FI) and THI.

RESULTS

In patients with good echocardiographic image quality, excellent correlations between the percentage of area occupied by myocardial fibrosis (% fibrosis) and the mean of integrated backscatter during a cardiac cycle (m-IB) measured with FI or THI were seen, and the correlation was closer with THI compared with FI. While in patients with poor image quality the correlation between m-IB and % fibrosis was only modest with FI, but the correlation was excellent with THI. Four cut-off values of m-IB with THI obtained from receiver operating characteristic curve discriminated between % fibrosis of more and less than 25, 30, 35, and 40% with high sensitivity and specificity. Multivariate analysis revealed that m-IB with THI was an independent predictor for discrimination of the severity of myocardial fibrosis.

CONCLUSION

Combined IB and THI are a clinically applicable method and may be an alternative to myocardial biopsy in evaluating quantitatively myocardial fibrosis in DCM.