Relation of endothelial and cardiac autonomic function with left ventricle diastolic function in patients with type 2 diabetes mellitus

Background and aims: Diabetes mellitus (DM) is a risk factor for left ventricle (LV) diastolic dysfunction. Aim of this study was to investigate whether endothelial and/or autonomic dysfunction are associated with LV diastolic dysfunction in DM patients. Methods: We studied 84 non-insulin-dependent type 2 DM (T2DM) patients with no heart disease by assessing: 1) LV diastolic function by echocardiography; 2) peripheral vasodilator function, by measuring flow-mediated dilation (FMD) and nitrate-mediate dilation (NMD); 3) heart rate variability (HRV) on 24-h Holter electrocardiographic monitoring. Results: Twenty-five patients (29.8%) had normal LV diastolic function, while 47 (55.9%) and 12 (14.3%) showed a mild and moderate/severe diastolic dysfunction, respectively. FMD in these 3 groups was 5.25 ± 2.0, 4.95 ± 1.6 and 4.43 ± 1.8% (p = 0.42), whereas NMD was 10.8 ± 2.3, 8.98 ± 3.0 and 8.82 ± 3.2%, respectively (p = 0.02). HRV variables did not differ among groups. However, the triangular index tended to be lower in patients with moderate/severe diastolic dysfunction (p = 0.09) and a significant correlation was found between the E/e’ ratio and both the triangular index (r = −0.26; p = 0.022) and LF amplitude (r = −0.29; p = 0.011). Conclusions: In T2DM patients an impairment of endothelium-independent, but not endothelium-dependent, dilatation seems associated with LV diastolic dysfunction. The possible role of cardiac autonomic dysfunction in diastolic dysfunction deserves investigation in larger populations of patients

Modeling and Experimental Studies of Peeling of Polymer Coating for Biodegradable Magnesium Alloy Stents

Biodegradable magnesium alloy stents (MAS) could improve the long-term clinical results of commercial bare metal or drug-eluting stents. MAS have shown a limited mechanical support for diseased vessels due to fast degradation. Protective polymer coating is a reasonable way to reduce the degradation rate of MAS. However, peeling of the coating during stent expansion is the main obstacle in stent application. In this study, experimental and computational methods were used to study the peeling problem of an optimized MAS design. The 90º peeling test provided the critical energy release rate with cohesive zone method to be used in the simulation study; the 90º peeling modeling had good agreement with the experimental test. Using reliable cohesive element material parameters, the simulation could verify whether the peeling happened when the coated MAS was expanded. The aim of this study is to provide an easy and reliable method to approach peeling problem of MAS, giving the instructions for the improvement of MAS coatings