Abstract
BackgroundBecause cardiomyopathy is the leading cause of death in diabetic patients, the determination of myocardial function in diabetes mellitus is essential. In the present study, we provide an integrated approach, using noninvasive echocardiography and invasive hemodynamics to assess early changes in myocardial function of diabetic rats.MethodsDiabetes was induced by streptozotocin injection (STZ, 50 mg/kg). After 30 days, echocardiography (noninvasive) at rest and invasive left ventricular (LV) cannulation at rest, during and after volume overload, were performed in diabetic (D, N = 7) and control rats (C, N = 7). The Student t test was performed to compare metabolic and echocardiographic differences between groups at 30 days. ANOVA was used to compare LV invasive measurements, followed by the Student-Newman-Keuls test. Differences were considered significant at P < 0.05 for all tests.ResultsDiabetes impaired LV systolic function expressed by reduced fractional shortening, ejection fraction, and velocity of circumferential fiber shortening compared with that in the control group. The diabetic LV diastolic dysfunction was evidenced by diminished E-waves and increased A-waves and isovolumic relaxation time. The myocardial performance index was greater in diabetic compared with control rats, indicating impairment in diastolic and systolic function. The LV systolic pressure was reduced and the LV end-diastolic pressure was increased at rest in diabetic rats. The volume overload increased LVEDP in both groups, while LVEDP remained increased after volume overload only in diabetic rats.ConclusionThese results suggest that STZ-diabetes induces systolic and diastolic dysfunction at rest, and reduces the capacity for cardiac adjustment to volume overload. In addition, it was also demonstrated that rodent echocardiography can be a useful, clinically relevant tool for the study of initial diabetic cardiomyopathy manifestations in asymptomatic patients.
Highlights
Because cardiomyopathy is the leading cause of death in diabetic patients, the determination of myocardial function in diabetes mellitus is essential
Noninvasive evaluation of cardiac function Echocardiography 30 days after STZ demonstrated that left ventricular (LV) internal dimension during diastole increased (0.73 ± 0.03 vs. 0.63 ± 0.03, D vs. C, P < 0.05), and the thickness of the interventricular septum and of the posterior wall during diastole decreased (0.101 ± 0.003 vs. 0.138 ± 0.005 and 0.1 ± 0.003 vs. 0.138 ± 0.005, D vs. C, P < 0.001, respectively) in diabetic rats in relation to control rats
LV diastolic function was observed after 30 days of STZ-induced diabetes, as expressed by reduced E-wave (m/s) (0.44 ± 0.036 vs 0.53 ± 0.04, D vs. C, P < 0.05) and increased A-wave (m/s) (0.4 ± 0.04 vs. 0.33 ± 0.02, D vs. C, P < 0.05) in diabetic animals when compared with control animals
Summary
Because cardiomyopathy is the leading cause of death in diabetic patients, the determination of myocardial function in diabetes mellitus is essential. We provide an integrated approach, using noninvasive echocardiography and invasive hemodynamics to assess early changes in myocardial function of diabetic rats. LV cannulation is a well-established, precise invasive method, not devoid of autonomic reflexes and ventricular-vascular coupling, this technique is limited because of the difficulty in keeping a catheter in the left ventricle throughout the long study period, and it is not without risk and does not allow assessment of the time course of cardiovascular changes. Several studies have used echocardiography as one noninvasive methodology to identify cardiac dysfunction associated with diabetes mellitus, no previous studies have used one integrated approach, ie, echocardiography and in vivo hemodynamics, to evaluate cardiac function in an experimental diabetes model. The purpose of the present study was characterization of early myocardial dysfunction performed at the same time by noninvasive echocardiography and invasive LV catheterization in STZ-induced diabetic rats
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
