Female gender increases stiffness of elastic but not of muscular arteries in type I diabetic patients.

The reason for the particularly increased risk for cardiovascular complications in diabetic women is still unclear. We have previously found decreased distensibility of elastic arteries in type I diabetic women, indicating increased cardiac load, not seen in type I diabetic men, which might be one contributing factor. Whether the effect of gender is different in muscular arteries in type I diabetic patients has not been assessed. As estimates of arterial distensibility we measured stiffness (beta) and pressure strain elastic modulus (Ep) in the muscular common femoral artery using echo-tracking sonography in 30 women (mean age 34 years, range 20-61) and 26 men (mean age 38 years, range 22-56) with type I diabetes. The results were compared with those of 89 healthy individuals of corresponding age and gender and with previously published results from elastic arteries in these patients obtained at the same occasion. The internal common femoral diameter was significantly decreased in both diabetic men and women. In sharp contrast to the highly significant decreased distensibility of the elastic abdominal aorta and common carotid artery in the type I diabetic women, the distensibility of the common femoral artery did not clearly differ between patients and controls, neither for women nor for men. Thus, the gender difference in changes of arterial distensibility found in elastic arteries was absent or far less obvious in the femoral artery. In conclusion, female gender seems to affect the mechanical properties of elastic, but not of large muscular arteries in type I diabetic patients. Thus, putative gender differences in arterial changes in type I diabetes are to be sought in elastic rather than muscular arteries

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.Journal of Human Hypertension advance online publication, 2 January 2014; doi:10.1038/jhh.2013.126

Reduced Aortic Wall Stress in Diabetes Mellitus

ObjectiveMost risk factors are similar for abdominal aortic aneurysm (AAA) and atherosclerosis, e.g. smoking, male gender, age, high blood pressure, hyperlipidemia. Diabetes mellitus however, is a risk factor for atherosclerosis, but diabetic patients seldom develop AAA. The reason for this discrepancy is unknown. Increased aortic wall stress seems to be an etiologic factor in the formation, growth and rupture of AAA in man. The aim of our study was to study the wall stress in the abdominal aorta in diabetic patients compared with healthy controls.Methods39 patients with diabetes mellitus and 46 age – and sex matched healthy subjects were examined with B-mode ultrasound to determine the lumen diameter (LD) and intima-media thickness (IMT) in the abdominal aorta (AA) and the common carotid artery (CCA). Diastolic blood pressure (DBP) was measured non-invasively in the brachial artery. LaPlace law was used to calculate circumferential wall stress.ResultsAge, DBP, and LD in the abdominal aorta were not significantly different in the diabetic patients compared to controls. IMT in the AA was larger in the diabetic patients, 0.89±0.17 vs 0.73±0.11mm (p<.001). Accordingly aortic wall stress was reduced in the diabetics, 7.8±1.7×105 vs 9.7±1.9×105dynes/cm2 (p<.001).ConclusionsWall stress in the abdominal aorta is reduced in diabetes mellitus. This is mainly due to a thicker aortic wall compared to healthy controls. The reduced aortic wall stress coincides with the fact that epidemiological studies have shown a decreased risk of aneurysm development in diabetic patients

Altered vascular function in healthy normotensive pregnant women with bilateral uterine artery notches.

OBJECTIVES: To assess endothelial function and vascular mechanical properties in normotensive pregnant women with high resistance in the uteroplacental circulation. DESIGN: Cross-sectional prospective study. SETTING: Doppler ultrasound laboratory at university department of obstetrics and gynaecology referral centre for high risk pregnancies. PARTICIPANTS: Forty-two caucasian normotensive pregnant women: 23 with uncomplicated pregnancies and 19 with bilateral uterine artery notches. METHODS: Flow-mediated dilatation of the brachial artery was measured by ultrasonography at 25 gestational weeks. Concentrations of nitrite and nitrate in the plasma were established at 25 and 32 gestational weeks. The elastic properties of the common carotid artery, abdominal aorta and popliteal artery were measured with an ultrasonic echo-tracking system. RESULTS: Flow-mediated dilatation at two minutes after cuff deflation was significantly lower in the bilateral notch group compared with the control group, 8.3% and 13.7%, respectively (P = 0.0007). The ability to sustain vasodilatation was reduced in the bilateral notch group (P = 0.02). Lower values of nitrite and nitrate in the plasma were found at 32 gestational weeks in the bilateral notch group than in the control group (mean 24.76 microM/L (SD 5.6) and 30.93 microM/L (8.2), respectively; P = 0.008). Nitrite and nitrate levels tended to be lower in the bilateral notch group even at 25 gestational weeks (29.45 microM/L (8.3) and 35.73 microM/L (11.0) in the bilateral notch and control group, respectively; P = 0.09). There was no difference in aortic, carotid or popliteal elasticity between the two groups. CONCLUSIONS: Healthy normotensive pregnant women with bilateral uterine artery notches show impaired endothelial function, but no differences in vascular mechanical properties

Is There a Relationship between Abdominal Aortic Aneurysms and Alpha1-antitrypsin Deficiency (PiZ)?

AbstractObjective:to determine if the frequency of α1AT deficiency (PiZ) is increased in patients with abdominal aortic aneurysm (AAA), and, to investigate whether aneurysmal stiffness and other clinical characteristics differ in AAA patients with and without α1AT deficiency.Methods:we identified α1AT-deficient individuals by a monoclonal-antibody ELISA technique, in 102 consecutive patients with AAA. Positive ELISA samples were further phenotyped by isoelectric focusing to differentiate between the heterozygosity (PiZ) and homozygosity (PiZZ) state. Aneurysmal diameter and stiffness was measured using echotracking sonography and blood pressure measurements.Results:the frequency of heterozygous α1AT deficiency (PiZ) in patients with AAA was similar to that in the general population (6.8% and 4.7%, respectively,p>0.3). The frequency of popliteal and femoral aneurysm was similar in male PiZ-carriers and non-carriers with AAA, as were age at diagnosis of AAA, aneurysmal diameter, aneurysmal stiffness, and presence of factors that may be associated with AAA (i.e. smoking, hypertension, diabetes mellitus, and family history of AAA). Occurrence of ischaemic heart disease was more frequent in male non-PiZ-carriers than in male PiZ-carriers with AAA (p=0.03).Conclusions:the frequency of α1AT deficiency (PiZ) was not increased in our series of patients with AAA and patients in whom the two disorders coexisted did not appear to have different clinical characteristics except for the lower occurrence of ischaemic heart disease among the PiZ-carriers

Reduced venous compliance in lower limbs of aging humans and its importance for capacitance function

Venous compliance in the calf of humans and its importance for capacitance function in relation to age were studied with the aid of 22, 44, and 59 mmHg lower body negative pressure (LBNP). Negative pressure transmission to the calf as well as changes in calf volume were studied, and venous compliance was calculated [change in volume with pressure change (dV/dP)]. The change in capacitance response of the calf with age (20-70 yr) was evaluated during LBNP 44 mmHg. Transmission of negative pressure to the subcutaneous tissue was almost full without any changes with age (92%). However, it was reduced to 80% in the underlying muscle tissue, irrespective of depth. Venous compliance in the young was 0.051 ml . 100 ml-1 . mmHg-1 and was reduced by 45% to 0.029 ml . 100 ml-1 . mmHg-1 in the old (P < 0.05). Accordingly, the capacitance response was reduced by 0.015 ml . 100 ml-1 . yr-1 (P < 0.005). Furthermore, the hemodynamic response to hypovolemic circulatory stress was attenuated with age. The reduced pressure transmission in muscle tissue is probably due to restriction of the muscle fascia envelope. The reduced venous compliance with age and the concomitant reduction in capacitance response during LBNP have implications for both the sympathetic reflex responses as well as the capacitance response during acute hypovolemic circulatory stress, which might be defected in aging humans

Reduced capillary hydraulic conductivity in skeletal muscle and skin in Type I diabetes : a possible cause for reduced transcapillary fluid absorption during hypovolaemia

AIMS/HYPOTHESIS: Patients with Type I (insulin-dependent) diabetes mellitus have a reduced transcapillary fluid absorption from skeletal muscle and skin and thus defective plasma volume regulation during hypovolaemia. Our aim was to find whether a defective capillary filtration coefficient or impaired transcapillary driving force are aetiologic factors for this reduction.METHODS: We investigated 11 diabetic patients (diabetes duration 6.9 +/- 1.1 years, age 26 +/- 1 years), without complications and 12 control subjects (26 +/- 1 years). Their capillary filtration coefficient was measured in the upper arm using a volumetric technique at rest and during lower body negative pressure (LBNP). We calculated the driving force for transcapillary fluid transfer.RESULTS: The increase in heart rate and the decrease in systolic blood pressure during lower body negative pressure were similar in diabetic and control subjects. The resting capillary filtration coefficient was decreased in the diabetic subjects, 0.033 +/- 0.003 vs 0.051 +/- 0.007 ml x 100 ml(-1) x min(-1) x mmHg(-1) (p < 0.05). During lower body negative pressure, the capillary filtration coefficient increased 35 % in both groups compared with resting capillary filtration coefficient and was still decreased in diabetes; 0.046 +/- 0.004 compared with 0.069 +/- 0.006 ml x 100ml(-1) x min(-1) x mmHg(-1) (p < 0.01). The established driving force during lower body negative pressure was 1.37 +/- 0.11 vs 1.30 +/- 0.15 mmHg (NS) in diabetic and control subjects, respectively.CONCLUSIONS/INTERPRETATION: Our study indicates that a reduced capillary filtration coefficient rather than defective regulation of transcapillary driving force, is the reason for the reduced transcapillary fluid absorption during hypovolaemic circulatory stress found in Type I diabetic patients