Insulin Stimulation Reduces Aortic Waveform in Adults with Metabolic Syndrome

Adults with metabolic syndrome (MetS) have increased fasting arterial stiffness and altered central hemodynamics that contribute, partly, to increased cardiovascular disease (CVD) risk. Although insulin affects aortic wave reflections in healthy adults, the effects in individuals with MetS are unclear. We hypothesized that insulin stimulation would reduce measures of pressure waveforms and hemodynamics in people with MetS. Thirty-five adults with obesity (27F; 54.2 ± 6.0 yr; 37.1 ± 4.8 kg/m2) were selected for MetS (ATP III criteria) following an overnight fast. Pulse wave analysis was assessed using applanation tonometry before and after a 2hr euglycemic-hyperinsulinemic clamp (90 mg/dl, 40 mU/m2/min). Deconvolution analysis was used to decompose the aortic waveform (augmentation index corrected to heart rate of 75 bpm (AIx@75); augmentation pressure (AP)) into backward and forward pressure components. Aerobic fitness (VO2max), body composition (DXA), and blood biochemistries were also assessed. Insulin significantly reduced augmentation index (AIx@75, 28.0 ± 9.6 vs. 23.0 ± 9.9 %, P<0.01), augmentation pressure (14.8 ± 6.4 vs. 12.0 ± 5.7 mmHg, P<0.01), pulse pressure amplification (1.26 ± 0.01 vs. 0.03 ± 0.01, P=0.01), and inflammation (hsCRP: P=0.02; MMP-7: P=0.03) compared to fasting. In subgroup analyses to understand HTN influence, there were no insulin stimulation differences on any outcome. VO2max, visceral fat, and blood potassium correlated with fasting AIx@75 (r=-0.39, P=0.02; r=0.41, P=0.03; r=-0.53, P=0.002). Potassium levels were also associated with insulin-mediated reductions in AP (r=0.52, P=0.002). Our results suggest insulin stimulation improves indices of aortic reflection in adults with MetS.

Residential Proximity to Greenness Mitigates the Hemodynamic Effects of Ambient Air Pollution

Background: Residential proximity to greenness is associated with a lower risk of cardiovascular disease (CVD) and all-cause mortality. However, it is unclear whether the beneficial effects of greenness are linked to a reduction in the effects of ambient air pollutants. Methods and Results: We measured arterial stiffness in 73 participants with moderate to high CVD risk. Average levels of ambient PM2.5 and ozone were calculated from local monitoring stations. Residential greenness was estimated using satellite-derived normalized difference vegetation index (NDVI) for a 200m and 1km radius around each participant's home. Participants were 51% female; average age of 52 years; and, 79% had diagnosed hypertension. In multiple linear regression models, residential NDVI was negatively associated with augmentation index (-3.8% per 0.1 NDVI). Ambient levels of PM2.5 (per interquartile range (IQR) of 6.9 μg/m3) were positively associated with augmentation pressure (3.1 mmHg), pulse pressure (5.9 mmHg), and aortic systolic pressure (8.1 mmHg). Ozone (per IQR of 0.03 ppm) was positively associated with augmentation index (5.5%), augmentation pressure (3.1 mmHg), and aortic systolic pressure (10 mmHg). In areas of low greenness, both PM2.5 and ozone were positively associated with pulse pressure. Additionally, ozone was positively associated with augmentation pressure and systolic blood pressure. However, in areas of high greenness, there was no significant association between indices of arterial stiffness with either PM2.5 or ozone.Conclusions: Residential proximity to greenness is associated with lower values of arterial stiffness. Residential greenness may mitigate the adverse effects of PM2.5 and ozone on arterial stiffness.

School-Based Exercise Intervention Improves Blood Pressure and Parameters of Arterial Stiffness in Children: A Randomized Controlled Trial

Purpose: To evaluate the effectiveness of a school-based exercise intervention on endurance performance (EP), blood pressure (BP), and arterial stiffness in children. Methods: A total of 105 students (mean age = 8.2 [0.6] y; 51% girls; body mass index = 17.8 [3.0] kg/m2) were randomized to the intervention group (IG, n = 51) and control group (CG, n = 54). During a 37-week experimental period, the IG received an exercise intervention (2 × 45 min/wk) in addition to their regular school physical education class (3 × 45 min/wk). EP, peripheral and central BP, pulse pressure, augmentation pressure, augmentation index, and aortic pulse wave velocity were assessed. Results: Following the intervention, significant changes (P < .05) in EP, peripheral and central systolic BP, pulse pressure, augmentation pressure, augmentation index, and aortic pulse wave velocity were found in the IG. Children in the CG displayed significant changes in peripheral and central diastolic BP. An analysis of the baseline-to-post changes revealed significant between-group differences in EP (P < .001), pulse pressure (P = .028), augmentation pressure (P = .007), and aortic pulse wave velocity (P = .037) that favored the IG and in peripheral and central diastolic BP that favored the CG. Conclusion: The school-based exercise intervention had beneficial effects not only on EP but also on different hemodynamic parameters.

Clinical implication of right-sided augmentation pressure in patients with pulmonary hypertension

Similar to left ventricular and aortic pressure waveforms, augmentation pressure (AugPr) in the right ventricular (RV) pressure waveform is also frequent in patients with pulmonary hypertension (PH). This study sought to evaluate whether the degree of AugPr in RV pressure waveform has prognostic value. Forty-one patients (13 men; mean age = 50.7 ± 16.1 years) with group 1 PH (mean pulmonary artery pressure [mPAP] ≥ 25 mmHg) who underwent cardiac catheterization as part of their work-up were retrospectively enrolled. Patients were divided into three groups. Group A: AugPr/RV systolic pressure < 25%; group B: AugPr/RV systolic pressure ≥ 25%; and group C: no discernible AugPr but showing peaked RV pressure waveform. Ten patients were included in group A (male-to-female ratio 3:7; mean age = 45.9 ± 12.1 years), 12 in group B (4:8, 53.8 ± 14.6 years), and 19 in group C (6:13, 51.8 ± 18.7 years). No differences in mPAP were seen between the three groups. Pulse pressure was significantly higher in group C compared to group A. Eight patients died during the mean follow-up period of 35.9 ± 30.7 months; the incidence of death was significantly higher in group C than in the other groups (one patient in group A and seven patients in group C). AugPr in RV pressure waveform has prognostic value in patients with PH. Therefore, additional attention should be given to the RV pressure waveform in patients with PH undergoing invasive pressure measurements as a part of their work-up.