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Objective To investigate the value of 7.0T cardiac magnetic resonance tissue tracking imaging (CMR-TT) in evaluation of cardiac function in rats with early left ventricular remodeling induced by isoproterenol (ISO). Methods Eighteen male healthy specific pathogen-free (SPF) SD rats were randomly divided into control (n=6) and model group (n=12).The rat model of early left ventricular remodeling was established by subcutaneous multipoint injection of 10 mg·kg-1·d-1 ISO solution for 10 d.After modeling, 7.0T CMR cine sequence scans were performed immediately, and the post-processing software CVI42.0 was used to analyze and compare the differences in each left ventricular (LV) function and myocardial strain parameters between the 2 groups of rats.Enzyme-linked immunosorbent assay (ELISA) was performed to detect cardiac troponin Ⅰ(cTn-Ⅰ) and N-terminal B-type natriuretic peptide (NT-pro BNP) levels in right atrial transvenous serum.Pearson correlation analysis was employed to analyze the correlation of left ventricular ejection fraction (LVEF), cTn-Ⅰ and NT-pro BNP levels with each overall myocardial strain parameter of LV. Results The results of imaging, serology and pathology displayed that that the model group showed obvious hypertrophy of the LV myocardium and different damage at each base of the myocardium, resulting in a significant decrease in conventional cardiac function and myocardial strain parameters of LV, which was the symbol of myocardial contractile dysfunction.Compared with the control group, heart mass (HM), heart mass index (HMI), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular myocardial mass (LVM), left ventricular end-diastolic maximum wall thickness (LVEDTHmax), and left ventricular remodeling index (LVRI) were significantly greater in the rats of the model group (P < 0.05).LVEF, left ventricular global circumferential strain (LVGCS), left ventricular global radial strain (LVGRS), left ventricular global longitudinal strain (LVGLS), LVGRS-Mid-cavity, LVGRS-Apical, LVGCS-Mid-cavity, LVGCS-Apical, LVGLS-Basal, and LVGLS-Apical decreased in different degrees (P < 0.05).The changes in LVEF and cTn-Ⅰ and NT-pro BNP levels were all correlated with the changes in each overall LV myocardial strain parameter. Conclusion CMR-TT can be used to assess cardiac dysfunction in early left ventricular remodeling. x

Several strategies for mapping ventricular outflow tract tachycardia have been reported as useful indices for differentiating between those originating from the right and the left side. Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an ultrasonographic technique that measures the myocardial motion amplitude towards the transducer in each region during systole, identifying regional myocardial displacement on the basis of myocardial velocities using color Doppler myocardial imaging principles. In this technique, the origin of the arrhythmia could be recognized as the site where the earliest color-coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary studies this modality was found to be useful in differentiating out flow tract ventricular tachycardias. ECCS was always found below or at the level of the pulmonary valve in all arrhythmias which could be ablated from the right ventricular outflow tract, while in those where the origin was above the pulmonary valve could be ablated from the left sinus of valsalva. These results indicate that TTI can provide detailed and accurate information on the arrhythmia origin of OT-VT and may be useful for differentiating between an OT-VT originating from the LV epicardium remote from the LSV and that from the LSV. Newer advances in echocardiographic technologies like high resolution, high frame rate real time three dimensional echocardiography with speckle tracking may further improve the precise localization of arrhythmias in the future.

Idiopathic outflow tract arrhythmias (ventricular tachycardias or symptomatic premature ventricular contractions; OT-VT/PVCs) can originate from the left ventricular (LV) epicardium (Epi-VT/PVCs), and radiofrequency (RF) energy applications from the aortic sinus of Valsalva can eliminate Epi-VT/PVCs in selected patients. Among the various ECG findings, the R-wave duration index and R/S amplitude index in leads V1 or V2 are useful for identifying Epi-VT/PVCs, and the Q-wave ratio of leads aVL to aVR and S-wave amplitude in lead V1 are useful for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the left sinus of Valsalva (LSV) and that from the LSV. Tissue tracking imaging is a promising modality for identifying the origin of OT-VT/PVCs and for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the LSV and that from the LSV. If the origin of the Epi-VT/PVC is identified within the LSV, coronary and aortic angiography should be performed to assess the anatomic relationships between the Epi-VT/PVC origin and coronary arteries and aortic valve before the RF energy delivery. To avoid potential complications, RF ablation should be performed at the LSV using a maximum power of 35 watts and maximum temperature of 55°C. Epicardial mapping through the coronary venous system and the presence of potentials recorded from the ablation site within the LSV and their changes before and after the RF energy applications may be useful for diagnosing Epi-VT/PVCs or predicting a successful catheter ablation from the LSV.

Objective: To evaluate with 7T cardiac magnetic resonance tissue tracking imaging (CMR-TT) the ameliorative effect of Cang-ai volatile oil (CAVO) on left ventricular remodeling (LVR) in rats induced by isoproterenol (ISO), and to make preliminary investigation into CAVO's effects on endothelial dysfunction in LVR., Methods: A total of 35 healthy male Sprague-Dawley (SD) rats were randomly assigned to two groups, the experimental group ( n =27) and the normal control group ( n =8). The rat model of LVR was established by subcutaneous injection of ISO solution at 10 mg·kg -1 ·d -1 at multiple sites for 10 consecutive days. After modeling was completed, the surviving rats ( n =24) in the experimental group were then randomly assigned to the blank experimental group, CAVO group, and Shexiang Baoxin pill (SXBXP) group ( n =8 in each group). Rats in each group were given via gavage the corresponding intervention medicine or an equivalent amount of normal saline solution for 28 consecutive days. At the end of modeling and intragastric intervention, 7T CMR cine sequence scanning was conducted to collect data. Then, post-processing software CVI42 was used to analyze the images and to compare and contrast the changes in the parameters of left ventricular cardiac function and myocardial strain in each group before and after the administration of the medication. The rats were sacrificed after MRI scanning, and their hearts were harvested for pathological examination. The levels of serum biochemical indicators were measured by enzyme-linked immunosorbent assay (ELISA)., Results: CAVO significantly increased LV ejection fraction and overall myocardial strain parameters in LVR rats, while it decreased LV volume, mass, and serum levels of endothelial function indicators in LVR rats. In addition, pathological staining showed marked improvements in the hypertrophy, necrosis and interstitial fibrosis of cardiomyocytes., Conclusion: Through the regulation of myocardial vascular endothelial function, CAVO can significantly improve cardiac functions in LVR rats, delay the process of ventricular remodeling, and have a certain amount of protective effect on cardiac structure and function in rats., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)