Effects of Impaired Fasting Glucose on Aortic Elasticity

Impaired glucose control is associated with multiple cardiovascular impairments

BACKGROUND

Impairments in several markers of the cardiovascular system have been described in impaired glucose tolerance (IGT) and diabetes, but the relative importance of those is not known. We aimed to investigate which cardiovascular markers were most closely linked to an impaired glucose control.

METHOD

In a population-based study of individuals all aged 50 years, the Prospective study of Obesity, Energy and Metabolism (POEM), 502 subjects were thoroughly investigated regarding endothelial function, arterial compliance, heart rate variability, arterial blood flow and atherosclerosis, performance at an exercise test with gas exchange (VO₂ and VCO₂ ), left ventricular structure and function, lung function and multiple measurements of blood pressure. Based on an oral glucose tolerance test (OGTT), the participants were grouped into normal, IGT and diabetes.

RESULTS

Of all haemodynamic and structural variables analysed, an impaired glucose control was most closely related to resting heart rate (based on chi-square value at ANOVA). Heart rate was followed by maximal workload, VO₂ recovery 5 min following exercise, reflectance index at pulse wave analysis, manual systolic blood pressure, ambulatory pulse and pulse pressure, echogenicity of carotid intima-media complex at ultrasound, and pulse wave velocity (p < .0005 for all variables). All of these variables still showed p < .05 versus an impaired glucose control following adjustment for BMI.

CONCLUSION

Of multiple measured cardiovascular markers, resting heart rate was most closely related to an impaired glucose control. Also exercise capacity and the recovery in VO₂ following exercise were amongst the top-ranked cardiovascular impairments linked to an impaired glucose control.

Evaluation of carotid artery elasticity changes in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes is one of the most common causes of cardiovascular disease as it causes arterial stiffness changes. The purpose of this study is to characterize, in vivo, carotid arterial structural and functional changes by applying radio frequency and X-strain ultrasound techniques.

METHODS

Ninety-one subjects were assigned into two groups; a diabetes group and a control group. Structural and functional changes in the common carotid arterial wall were investigated by quality intima-media thickness (QIMT), quality arterial stiffness (QAS), and X-strain analysis with a Mylab Twice ultrasound instrument. The relationships among variables between the two groups were analyzed in this study.

RESULTS

There was no significant difference in carotid IMT (626.5 ± 169.1 μm vs. 568.5 ± 122.6 μm, P = 0.1506) between two groups. Pulse wave velocity (PWV) and stiffness index (β) were remarkably greater (8.388 ± 3.254 m/s vs. 7.269 ± 1.332 m/s; 12.51 ± 14.16 vs.9.279 ± 2.871), while compliance coefficient (CC) decreased significantly in the diabetes group (0.802 ± 0.3094 mm2/Kpa vs. 0.968 ± 0.3992 mm2/Kpa) (P < 0.05). The displacement difference of radial (RD-D), longitudinal (LD-D) and rotation (ROT-D) directions were significantly different between two groups' comparison (P = 0.0212, P = 0.0235 and P = 0.0072, respectively). The time of circumferential peak strain difference (CS-DT) and the time of radial peak strain rate (RSR-T) were found to be significantly different between the two groups (341.9 ± 77.56 ms vs. 369.0 ± 78.26 ms, P = 0.0494; 142.7 ± 22.43 ms vs. 136.2 ± 30.70 ms, P = 0.0474). CS-TD and RSR-T were also found to be positively correlated with CC value (r = 0.3908, P < 0.005 and r = 0.3027, P = 0.0326, respectively). Finally, PWV was negatively correlated with CC with (r = -0.6177, P < 0.001).

CONCLUSIONS

In type 2 diabetes, the functional changes in CCA can be identified using the methods presented in this article earlier than the structural changes. Arterial stiffness values provided by QAS and X-strain analysis can be used as indicators of CCA functional lesions in patients with type 2 diabetes.

Predictive markers of abdominal aortic stiffness measured by echo-tracking in subjects with varying insulin sensitivity

Arterial stiffness is influenced by advancing age and vascular disease and is an independent risk factor for cardiovascular events and death. Using ultrasound measurements, arterial stiffness in a specific arterial segment can be assessed. The aim of this observational study was to explore the prospective and cross-sectional associations between arterial stiffness measured by ultrasound locally in the abdominal aorta and cardiovascular risk factors/markers including insulin resistance measured by the homeostatic model assessment-insulin resistance (HOMA-IR), lipids and abdominal obesity. This study includes 335 subjects from Malmö, Sweden, examined in 1991-1994 and again at follow-up in 1998-2000 (mean age 64 years, 42% men). Ultrasound measurement of the abdominal aorta was performed at follow-up investigation. In the female subgroup, there was a positive association between HOMA-IR at baseline and abdominal aortic stiffness at follow-up (β = 0.18, P = 0.03) and a negative association between high-density lipoprotein and aortic stiffness (β = -0.23, P = 0.005), independently of classical cardiovascular risk factors. These associations were not found among men. The results suggest a greater or different role of impaired glucose metabolism in the pathophysiology of arterial stiffness in women than in men.

Ascending aorta elasticity in children with isolated bicuspid aortic valve

BACKGROUND

Aortic dilation is common in children with bicuspid aortic valve (BAV) but aortic complications are infrequent. The aim of this study was to investigate elastic properties of the ascending aorta (AAo) and its relation to AAo size in children with isolated BAV without significant valve dysfunction.

METHODS

24 children with isolated BAV and 24 healthy controls with tricuspid aortic valve (TAV) matched by gender, age and body surface area (BSA) were studied. Aortic strain (AS), aortic distensibility (DIS) and aortic stiffness index (SI) were derived from M-mode echocardiography at the AAo together with cuff blood pressure recordings. BAV children with dilated AAo (z score ≥ 2) and non dilated (z score<2) were compared.

RESULTS

BAV children had larger aortas than controls at the sinuses of Valsalva, sinotubular junction and AAo (p<0.05). AS was lower in BAV than in controls (10.15 ± 4.93 vs 16.93 ± 5.17 p=0.000), DIS was lower in BAV than in controls (8.51 ± 3.90 vs 14.37 ± 4.20 p=0.000) and SI was higher in BAV than in controls (7.19 ± 4.45 vs 4.05 ± 2.33 p=0.04). There were no significant differences in AS, DIS and SI between children with dilated and non-dilated AAo. AS, DIS and SI were not related to BSA, age or AAo size.

CONCLUSIONS

AAo elasticity assessed by transthoracic echocardiography is impaired in BAV children without significant valve dysfunction compared to TAV children. Impaired elasticity seems to be independent from aortic dilation. Measuring aortic elasticity may help to identify children at greater risk for complications as adults.