Marta Focardi

Tumor Necrosis Factor-α Induces Endothelial Dysfunction in the Prediabetic Metabolic Syndrome

Inflammation is a condition that underscores many cardiovascular pathologies including endothelial dysfunction, but no link is yet established between the vascular pathology of the metabolic syndrome with a particular inflammatory cytokine. We hypothesized that impairments in coronary endothelial function in the obese condition the prediabetic metabolic syndrome is caused by TNF-&agr; overexpression. To test this, we measured endothelium-dependent (acetylcholine) and -independent vasodilation (sodium nitroprusside) of isolated, pressurized coronary small arteries from lean control and Zucker obese fatty (ZOF, a model of prediabetic metabolic syndrome) rats. In ZOF rats, dilation to ACh was blunted compared with lean rats, but sodium nitroprusside–induced dilation was comparable. Superoxide (&OV0151;) generation was elevated in vessels from ZOF rats compared with lean rats, and administration of the &OV0151; scavenger TEMPOL, NAD(P)H oxidase inhibitor (apocynin), or anti–TNF-&agr; restored endothelium-dependent dilation in the ZOF rats. Real-time PCR and Western blotting revealed that mRNA and protein of TNF-&agr; were higher in ZOF rats than that in lean rats, whereas eNOS protein levels were reduced in the ZOF versus lean rats. Immunostaining showed that TNF-&agr; in ZOF rat heart is localized in endothelial cells and vascular smooth muscle cells. Expression of NAD(P)H subunits p22 and p40-phox were elevated in ZOF compared with lean animals. Administration of TNF-&agr; more than 3 days also induced expression of these NAD(P)H subunits and abrogated endothelium-dependent dilation. In conclusion, the results demonstrate the endothelial dysfunction occurring in the metabolic syndrome is the result of effects of the inflammatory cytokine TNF-&agr; and subsequent production of &OV0151;.

Vascular Endothelial Growth Factor Is Required for Coronary Collateral Growth in the Rat

Background— The goal of this study was to determine whether the expression of vascular endothelial growth factor (VEGF) is critical for coronary collateral growth. Previous studies have provided an association between coronary collateral growth and VEGF, but none have allowed determination of a causal role. Methods and Results— We measured coronary collateral growth in rats subjected to repetitive episodes of myocardial ischemia (RI; one 40-second occlusion every 20 minutes for 2 hours 40 minutes, followed by 5 hours 20 minutes of rest, with this 8-hour cycle repeated 3 times per day for 10 days). Collateral growth was measured from blood flow (radioactive microspheres), visualization of arterial-arterial anastomoses (x-ray micro-CT), and maintenance of function during complete coronary occlusion in 3 groups of animals: sham (received instrumentation but no RI), experimental (subjected to RI), and anti–vascular endothelial growth factor (RI+anti-VEGF 0.6 mg/100 g per day) to block the endogenous actions of VEGF. In the 3 groups, native collateral flow (measurement for RI or sham protocol) averaged 0.2 to 0.3 mL · min−1 · g−1 of tissue. In the sham group, collateral flow did not increase during the protocol. Collateral flow in the control RI group increased by ≈6-fold to 1.63 mL · min−1 · g−1 tissue, but in the anti-VEGF group, collateral flow did not increase after the RI protocol (0.22 mL · min−1 · g−1). In acute experiments, collateral flow was unchanged during vasodilation with dipyridamole, indicating the increases in collateral flow are due to collateral growth and not vasodilation. X-ray micro-CT analysis revealed a 3-fold increase (versus sham group) in the number of arterial-arterial anastomoses per heart after RI, which was prevented by treatment with anti-VEGF. The growth of the collateral circulation was functional in the RI group because complete coronary occlusion did not induce any untoward effects on hemodynamics or arrhythmias. In the sham or anti-VEGF groups, coronary occlusion at the end of the protocol induced many arrhythmias and deterioration of function. Conclusions— From these results, we conclude that the expression of VEGF is critical to the growth of coronary collaterals.

Left atrial deformation analysis by Speckle Tracking echocardiography for prediction of cardiovascular outcomes.

The incremental value of left atrial (LA) deformation analysis by speckle tracking echocardiography compared with LA volume or LA ejection fraction as a cardiovascular risk marker has not been evaluated prospectively. We sought to compare LA function by speckle tracking echocardiography to other conventional LA parameters for prediction of adverse cardiovascular outcomes. This prospective study included 312 adults (mean age 71 ± 6 years, 56% men) in sinus rhythm who were followed for development of first atrial fibrillation, congestive heart failure, stroke, transient ischemic attack, myocardial infarction, coronary revascularization, and cardiovascular death. Global peak atrial longitudinal strain (PALS) by speckle tracking echocardiography was measured in all subjects by averaging all atrial segments. Left atrium was assessed with biplane LA volume, LA ejection fraction, 4-chamber LA area, and M-mode dimension. Of 312 subjects at baseline, 43 had 61 new events during a mean follow-up of 3.1 ± 1.4 years. All LA parameters, traditional parameters, and parameters derived by speckle tracking echocardiography were independently predictive of combined outcomes (p <0.0001 for all comparisons). Overall performance for prediction of cardiovascular events was greatest for global PALS (area under receiver operator characteristic curve: global PALS 0.83, indexed LA volume 0.71, LA ejection fraction 0.69, LA area 0.64, LA diameter 0.59). A graded association between degree of LA enlargement and risk of cardiovascular events was evident only for global PALS and indexed LA volume. In conclusion, global PALS is a strong and independent predictor of cardiovascular events and appears to be superior to conventional parameters of LA analysis.

Speckle tracking echocardiography as a new technique to evaluate right ventricular function in patients with left ventricular assist device therapy.

BACKGROUND Right ventricular (RV) systolic function has a critical role in determining the clinical outcome and the success of using left ventricular assist devices (LVADs) in patients with refractory heart failure. RV deformation analysis by speckle tracking echocardiography (STE) has recently allowed a deeper analysis of RV longitudinal function. The aim of the study was to observe RV function by STE in patients with advanced heart failure before and after LVAD implantation. METHODS Transthoracic echo Doppler was performed in 10 patients referred for LVAD therapy at baseline and with serial echocardiograms after LVAD implantation. In a sub-group of 4 patients, an echocardiographic evaluation was also made after intra-aortic balloon pump (IABP) support was initiated and before LVAD implantation. All echocardiographic images were analyzed off-line to calculate the free wall RV longitudinal strain (RVLS). RESULTS Three patients who presented the lowest free wall RVLS values at baseline, showed a progressive decline of RVLS after LVAD implant, presenting finally RV failure; however, patients with higher values of RVLS at baseline presented a further and overt increase of strain values in the course of follow-up. The overall performance for the prediction of RV failure after LVAD implant was greatest for free wall RVLS (area under the curve, 0.93). For the sub-group receiving the IABP as an intermediate step, only 2 patients with an increase of RVLS after IABP implantation also showed an increase of RVLS levels, after subsequent LVAD implantation. The 2 patients without an increase of RVLS after IABP implantation also presented with RV failure after LVAD therapy. CONCLUSIONS This study of 10 patients indicates that the new parameter of RVLS, representing RV myocardial deformation, may have important clinical implications for the selection and management of LVAD patients. A large multicenter study is required to confirm these observations and to quantify the clinical significance of changes in RVLS value.

Novel echocardiographic techniques for the evaluation of athletes’ heart: A focus on speckle-tracking echocardiography

Background The development and rapid dissemination of two-dimensional echocardiography led to important further advances in our understanding of athletes’ heart that has been the subject of several echocardiographic studies involving many thousands of athletes. The description of ventricular chamber enlargement, myocardial hypertrophy and atrial dilatation has led to a more comprehensive understanding of cardiac adaptation to exercise conditioning. Most recently, advanced echocardiographic techniques have begun to clarify significant functional adaptations of the myocardium that accompany previously reported morphological features of athletes’ heart. In particular, speckle-tracking echocardiography (STE) has recently provided further insights into the characterisation of myocardial properties. Discussion STE is a relatively new, largely angle-independent, non-invasive imaging technique that allows for an objective and quantitative evaluation of global and regional myocardial function. STE has enhanced our understanding of athletes’ heart through a comprehensive characterisation of biventricular and biatrial function, providing novel insights into the investigation of physiological adaptation of the heart to exercise conditioning. These peculiarities can provide further useful data to distinguish between athletes’ heart and cardiomyopathies. Furthermore, STE represents a promising tool to address new concerns on right ventricular function and to increase understanding of the complexity of the non-systemic circulation, especially in the athletic population. Conclusion This review article analyses new data on cardiac function in athletes by novel echocardiographic techniques with a particular attention to the application of STE to characterise biventricular and biatrial function in athletes.

Increased basal coronary blood flow as a cause of reduced coronary flow reserve in diabetic patients

A reduced coronary flow reserve (CFR) has been demonstrated in diabetes, but the underlying mechanisms are unknown. We assessed thermodilution-derived CFR after 5-min intravenous adenosine infusion through a pressure-temperature sensor-tipped wire in 30 coronary arteries without significant lumen reduction in 30 patients: 13 with and 17 without a history of diabetes. We determined CFR as the ratio of basal and hyperemic mean transit times (T(mn)); fractional flow reserve (FFR) as the ratio of distal and proximal pressures at maximal hyperemia to exclude local macrovascular disease; and an index of microvascular resistance (IMR) as the distal coronary pressure at maximal hyperemia divided by the inverse of the hyperemic T(mn). We also assessed insulin resistance by the homeostasis model assessment (HOMA) index. FFR was normal in all investigated arteries. CFR was significantly lower in diabetic vs. nondiabetic patients [median (interquartile range): 2.2 (1.4-3.2) vs. 4.1 (2.7-4.4); P = 0.02]. Basal T(mn) was lower in diabetic vs. nondiabetic subjects [median (interquartile range): 0.53 (0.25-0.71) vs. 0.64 (0.50-1.17); P = 0.04], while hyperemic T(mn) and IMR were similar. We found significant correlations at linear regression analysis between logCFR and the HOMA index (r(2) = 0.35; P = 0.0005) and between basal T(mn) and the HOMA index (r(2) = 0.44; P < 0.0001). In conclusion, compared with nondiabetic subjects, CFR is lower in patients with diabetes and epicardial coronary arteries free of severe stenosis, because of increased basal coronary flow, while hyperemic coronary flow is similar. Basal coronary flow relates to insulin resistance, suggesting a key role of cellular metabolism in the regulation of coronary blood flow.

Right ventricular remodelling induced by exercise training in competitive athletes

AIMS Conflicting evidence exists concerning right ventricular (RV) morphological and functional remodelling in trained athletes, with a very few longitudinal data prospectively investigating the RV changes. The aim of this study was to assess the morphological and functional RV changes occurring during the competitive season in young athletes engaged in the most popular team sports. METHODS AND RESULTS Twenty-nine top-level athletes (age: 20.9 ± 6.7 years), practicing basketball and volleyball, were evaluated at pre-season, mid-season, and end-season time-points, using tissue Doppler imaging and 2D speckle-tracking echocardiography. RV basal and mid-cavity end-diastolic diameters (EDDs; overall P = 0.011 and P < 0.0001, respectively), and RV diastolic area (overall P < 0.0001) increased during the season. Conversely, RV outflow tract did not vary (overall P = 0.96). During the season, no significant differences were observed in RV diastolic functional indexes and in RV fractional area change (overall P = 0.35). Global RV longitudinal strain did not significantly change (overall P = 0.52), although apical longitudinal strain significantly increased (overall P = 0.017). In association, left ventricular (LV) volume and mass increased during the season (overall P = 0.007). On multivariate analysis, LV mass was the only independent predictor of RVEDD at pre-season (β = 0.69, P < 0.0001) and at end-season (β = 0.82, P < 0.0001). CONCLUSIONS Right ventricular chamber size increases during the competitive season in top-level athletes, with no significant changes in the outflow tract. RV morphological adaptation in top-level athletes practicing team sports is not associated with a reduction in RV function or in myocardial deformation and occurs in close association with changes on the left ventricle, suggesting a physiological remodelling of the right ventricle.

Reduced levels of putative endothelial progenitor and CXCR4+ cells in coronary artery disease: Kinetics following percutaneous coronary intervention and association with clinical characteristics

Levels of circulating endothelial progenitor cells (EPCs) and CXCR4-positive cells are decreased in patients with coronary artery disease (CAD); however, their ability to change in response to acute vascular injury remains to be elucidated. Progenitor and CXCR4-positive cells were analysed by flow cytometry from the peripheral blood of 23 healthy controls and 23 patients with CAD, of which 13 patients underwent angiogram and 10 patients received percutaneous coronary intervention (PCI) with stent implantation. Baseline levels of progenitor and CXCR4-positive cells were substantially reduced in CAD patients compared to controls, although they were still capable of increasing in response to vascular injury. Levels of progenitor and CXCR4-positive cells were increased to a greater extent in the PCI group compared to angiogram patients. At presentation, levels of putative endothelial progenitor and CXCR4-positive cells were found to be negatively correlated with disease severity. A one-year follow-up revealed that out of the cell populations examined, only levels of CXCR4-positive cells were positively correlated with angina frequency in the PCI group, but not in patients receiving angiogram. Baseline levels of progenitor cells are differentially increased depending upon the severity of vascular injury incurred, regardless of a significant deficit in baseline levels in CAD patients. Levels of putative EPCs and CXCR4-positive cells were negatively correlated with disease severity at presentation, however, only CXCR4-positive cells were associated with patient condition in a one-year follow-up.

Dynamic changes in left ventricular mass and in fat-free mass in top-level athletes during the competitive season.

Background Previous cross-sectional studies have demonstrated that fat-free mass (FFM) is an important determinant of left ventricular mass (LVM) in athletes. However, cross-sectional investigations have not the ability to detect the dynamic adaptation occurring with training. We hypothesized that LVM adapts concurrently with the increase of FFM induced by exercise conditioning. We sought to study the relationship between the variations of LVM and of FFM occurring in top-level soccer players during the season. Methods Twenty-three male top-level athletes were recruited. LVM was assessed by echocardiography and FFM by dual-energy X-ray absorptiometry. Serial measurements were performed pre-season, after 1 month, at mid- and end-season, and after 2 months of detraining. Results LVM significantly increased at mid-season versus pre-season values, reaching the highest value at the end of the season (p < 0.05). While body weight did not vary during the study period, FFM significantly increased (p < 0.05 for mid-/end-season vs. pre-season data). After the detraining, no significant differences were observed between pre-season and detraining echocardiographic data. The only independent predictors of LVM were left ventricular stroke volume and FFM (R = 0.36, p = 0.005; R = 0.35, p = 0.005, respectively). When ΔLVM index was set as dependent variable, the only independent predictor was ΔFFM (R = 0.87, p = 0.002). Conclusions Changes in LVM occur in close association with changes in FFM, suggesting that the left ventricle adapts concurrently with the increase of the metabolically active tissue induced by training, i.e. the FFM. Therefore, the dynamic changes in FFM and LVM may reflect a physiological adaptation induced by intensive training.

Effects of training on LV strain in competitive athletes

Objective LV longitudinal strain, a recognised marker of LV function, has been recently applied to the evaluation of the athletes heart. At present, little is known about the influence of training on LV global longitudinal strain (GLS) in athletes. The aim of this study was to prospectively investigate the impact of training on LV longitudinal strain and twist mechanics in a cohort of competitive athletes. Methods Ninety-one competitive athletes, practising team sports and competing at national or international level, were analysed. Echocardiographic evaluation was performed at the beginning of the season (low training) and after 18±2 weeks of a supervised, intensive training programme (peak training). Results A significant increase in LV mass (p<0.0001), LV end-diastolic and end-systolic volume (p=0.0001 and <0.0001, respectively) was found at peak training. LV basal and apical torsion (p=0.59 and 0.43, respectively) and LV twisting (p=0.78) did not change, and only a mild increase in LV GLS was evident after training (p=0.044). Resting heart rate was identified as the only independent predictor of LV GLS after training (β=0.30, p=0.005). Conclusions A 18-week, intensive training programme induced only a slight increase in LV GLS despite marked changes in cardiac morphology, suggesting a physiological adaptation of the LV to exercise conditioning.