Relative influence of insulin resistance versus blood pressure on vascular changes in longstanding hypertension. ICARUS, a LIFE sub study. Insulin Carotids US Scandinavia

Effect of alpha-lipoic acid on arterial stiffness parameters in type 2 diabetes mellitus patients with cardiac autonomic neuropathy

Objective. Significantly underdiagnosed, diabetes-associated cardiac autonomic neuropathy (CAN) causes a wide range of cardiac disorders that may cause life-threatening outcomes. This study investigated the effects of alpha-lipoic acid (ALA) on arterial stiffness and insulin resistance (IR) parameters in type 2 diabetes mellitus (T2D) patients and definite CAN. Methods. A total of 36 patients with T2D and a definite stage of CAN were recruited. This investigation was carried out on two separate arms: traditional hypoglycemic therapy (n=18, control) and ALA (n=18) 600 mg in film-coated tablets/q.d. in addition to traditional hypoglycemic therapy. The duration of the study was three months. Results. In subjects with T2D and definite stage of СAN, treatment with ALA resulted in a significant decrease of glucose, immunoreactive insulin concentration, and Homeostasis Model Assessment (HOMA)-IR (HOMA-IR) parameters; pulse wave velocity (PWV), aorta augmentation index (AIxao) during the active period of the day and decrease of PWV, AIxao, and brachial augmentation index during the passive period of the day compared with the results, obtained in the control group. Therefore, the administration of ALA to patients with T2D for three months promotes the improvement of glucose metabolism and arterial stiffness parameters. Conclusions. In patients with T2D and definite stage of СAN treatment with ALA improved HOMA-IR and arterial stiffness parameters. These findings can be of clinical significance for the complex treatment of diabetes-associated CAN.

Hemodynamics and Vascular Hypertrophy in African Americans and Caucasians With High Blood Pressure

BACKGROUND

Hypertension in African Americans is characterized by greater systemic vascular resistance (SVR) compared with Caucasian Americans, but the responsible mechanisms are not known. The present study sought to determine if peripheral vascular hypertrophy is a potential mechanism contributing to elevated SVR in African Americans with high blood pressure (BP).

METHODS

In a biracial sample of 80 men and women between the ages of 25 and 45 years, with clinic BP in the range 130/85-160/99mm Hg, we assessed cardiac output and SVR, in addition to BP. Minimum forearm vascular resistance (MFVR), a marker of vascular hypertrophy, also was assessed.

RESULTS

SVR was elevated in African Americans compared with Caucasians (P < 0.001). Regression models indicated that age, body mass index, 24-hour diastolic BP, and ethnicity were significant predictors of SVR. There was also a significant interaction between ethnicity and MFVR in explaining SVR in the study sample. In particular, there was a significant positive association between MFVR and SVR among African Americans (P = 0.002), whereas the association was inverse and not statistically significant among Caucasians (P = 0.601).

CONCLUSION

Hypertrophy of the systemic microvasculature may contribute to the elevated SVR that is characteristic of the early stages of hypertension in African American compared with Caucasians.

Carotid artery stiffness is related to hyperinsulinemia and insulin-resistance in middle-aged, non-diabetic hypertensive patients

BACKGROUND AND AIMS

Glycometabolic abnormalities are frequently found in hypertension and could affect the mechanical properties of carotid arteries. The aim of the study was to investigate the relationship of glucose tolerance, plasma insulin, and insulin sensitivity with carotid distensibility in middle-aged, non-diabetic hypertensive patients free of cardiac and vascular complications.

METHOD AND RESULTS

In 93 patients with grade 1-2, uncomplicated, primary hypertension and 68 matched normotensive controls we measured plasma glucose and insulin at fast and after an oral glucose load (OGTT), calculated the HOMA-index as a marker of insulin sensitivity, and assessed distensibility of common carotid arteries by B-mode ultrasonography. Hypertensive patients were hyperinsulinemic and insulin-resistant as compared to normotensive controls. Hypertensive patients with impaired fasting glucose and/or impaired glucose tolerance had comparable distensibility of carotid arteries. Patients with decreased carotid distensibility were older and had higher body mass, fasting and post-OGTT plasma insulin, HOMA-index, and carotid IMT than the remaining patients, but no differences in glycated hemoglobin, and fasting or post-OGTT plasma glucose. Carotid coefficient of distensibility was inversely related and β-stiffness directly related with fasting and post-OGTT plasma insulin, and HOMA-index. Multivariate logistic regression showed that age and post-OGTT plasma insulin levels predicted carotid artery stiffening independent of body mass index, sex, blood pressure, and plasma glucose levels.

CONCLUSIONS

The study demonstrates that decreased insulin sensitivity and the related hyperinsulinemia but not hyperglycemia could contribute to carotid artery stiffening in middle-aged, non-diabetic hypertensive patients free of cardiovascular complications.

Arterial stiffness in diabetes and the metabolic syndrome: a pathway to cardiovascular disease

Increased arterial stiffness associated with diabetes and the metabolic syndrome may in part explain the increased cardiovascular disease risk observed in these conditions. Arterial stiffness can be estimated by quantifying pulse pressure but is better described by distensibility and compliance coefficients, pulse wave velocity and wave reflection. The most common non-invasive methodologies used to quantify these estimates of arterial stiffness (e.g. ultrasonography and applanation tonometry) are also described. We then review and summarise the current data on the associations between diabetes, the metabolic syndrome and insulin resistance on the one hand and greater arterial stiffness on the other, and identify and discuss some unresolved issues such as differential stiffening of central vs peripheral arterial segments, the impact of sex, and the pathobiology of increased arterial stiffness in diabetes and the metabolic syndrome. Finally, some considerations with regard to treatment options are presented. At present the most powerful therapy available for reducing arterial stiffness is to vigorously treat hypertension using pharmacological agents. New pharmacological strategies to reduce arterial stiffness are likely to be especially relevant to individuals with diabetes.

Long‐Term Effects of a Losartan‐Compared With an Atenolol‐Based Treatment Regimen on Carotid Artery Plaque Development in Hypertensive Patients With Left Ventricular Hypertrophy: ICARUS, a LIFE Substudy

In the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) study, there was a 25% risk reduction for stroke with angiotensin receptor blocker-based therapy (losartan) as compared with beta-blocker-based therapy (atenolol) despite comparable blood pressure reductions. This substudy examines treatment effects on the amount and density of atherosclerotic lesions in the common carotid arteries and the carotid bulb in 81 patients during 3 years of treatment. There were no statistically significant changes in the amount of carotid plaque in patients treated with losartan compared with an atenolol-based treatment program. A statistically nonsignificant increase in plaque density and index (average of plaque amount and density) was seen in the atenolol group compared with those treated with losartan. The small number of patients evaluated may have limited the power to detect a difference in outcome. The difference in carotid plaque index increase between the treatment groups during 3 years of treatment could not be statistically linked to specific treatments in the present substudy.

Insulin resistance and plasma triglyceride level are differently related to cardiac hypertrophy and arterial stiffening in hypertensive subjects

OBJECTIVE

The frequent association between the type 2 diabetes mellitus and cardio-vascular diseases suggests that metabolic factors may contribute to cardio-vascular remodeling. The aim of our study was to examine the relationships between left ventricular posterior wall thickness (LVPWT), pulse wave velocity (PWV), and the metabolic abnormalities of insulin resistance syndrome, in hypertensive patients.

METHODS

In 227 consecutive hypertensives, we examined the relationships between LVPWT, PWV, and metabolic factors: plasma glucose, insulin, total cholesterol, high density lipoprotein (HDL)-cholesterol, triglycerides levels as well as the homeostasis model assessment of insulin resistance (HOMA). The Pearson correlation coefficient and multiple regression analysis (including age, gender, body mass index, and 24-hour systolic blood pressure) were used as statistical tests.

RESULTS

In univariate analysis, glucose, HDL-cholesterol, and triglycerides levels were related to LVPWT (r = 0.19, p < 0.05; r = -0.26, p < 0.001; r = 0.31, p < 0.001, respectively); all metabolic variables, except HDL-cholesterol, correlated to PWV (plasma glucose r = 0.25, p < 0.001; total cholesterol r = 0.22, p < 0.01; triglycerides r = 0.20, p < 0.01; insulin r = 0.19, p < 0.01; HOMA r = 0.27; p < 0.001). In the multivariate model, plasma triglycerides remained correlated with LVPWT (beta = 0.19, p < 0.02) independently of systolic blood pressure, plasma aldosterone, and normetanephrine. Only HOMA and insulin level remained associated with PWV (beta = 0.14; beta = 0.13 respectively, p < 0.05).

CONCLUSIONS

These data suggest that among typical metabolic abnormalities of insulin resistance syndrome, plasma triglycerides, and insulin as well as degree of insulin resistance may contribute to cardiac hypertrophy and arterial stiffening independently of hemodynamic and hormonal factors.

Long-term treatment with losartan versus atenolol improves insulin sensitivity in hypertension: ICARUS, a LIFE substudy

OBJECTIVE

Hypertension and insulin resistance might be associated through peripheral vascular hypertrophy/rarefaction which compromises skeletal muscle blood flow and decreases glucose uptake, inducing insulin resistance. We hypothesized that treatment with losartan as compared to atenolol would improve insulin sensitivity through regression of peripheral vascular hypertrophy/rarefaction.

METHODS

In 70 hypertensive patients with electrocardiographic left ventricular hypertrophy, we measured minimal forearm vascular resistance (MFVR) by plethysmography and insulin sensitivity (M/IG) by a 2-h isoglycemic hyperinsulinemic clamp at baseline and after 1, 2 and 3 years of blinded treatment with atenolol- or losartan-based regimens.

RESULTS

Blood pressures were reduced similarly in the two treatment groups. After 3 years, MFVR was increased (3.7 versus 3.2 mmHg x min x 100, P < 0.05) and M/IG decreased (8.6 versus 12.1 l/kg x mmol x min, P < 0.05) in patients treated with atenolol, whereas MFVR and M/IG were unchanged (3.5 versus 3.5 mmHg x min x 100 and 12.6 versus 11.1 l/kg x mmol x min, both P = NS) in patients treated with losartan. As compared to atenolol, losartan treatment was associated with less increase in MFVR (4.3 versus 27%, P < 0.05) and less decrease in M/IG (24 versus -14%, P < 0.01). The relative change in M/IG was inversely associated with the relative change in MFVR (r = -0.16, P < 0.05) independently of the relative change in body mass index (r = -0.29, P < 0.001).

CONCLUSIONS

As compared to atenolol, losartan treatment was associated with less peripheral vascular hypertrophy/rarefaction and higher insulin sensitivity. The relative change in MFVR and M/IG were inversely related, supporting the hypothesis that peripheral vascular changes in hypertension may induce insulin resistance. The ability of losartan to preserve insulin sensitivity may explain the lower incidence of new onset diabetes in patients treated with losartan in the LIFE study.

Long-term plasma catecholamines in patients with hypertension and left ventricular hypertrophy treated with losartan or atenolol: ICARUS, a LIFE substudy

Hypertension is a major risk factor for morbidity and mortality. Plasma catecholamines are linked to the pathogenesis of hypertension. Pharmacological intervention, including treatment with beta-blockers, reduces cardiovascular mortality and morbidity. In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, the angiotensin receptor blocker losartan significantly reduced cardiovascular end points compared to the beta-blocker atenolol. Thus, for the first time, one drug was shown to be superior to another in hypertension. The present substudy examined the effects of atenolol vs losartan treatment on plasma catecholamines at rest and during hyperinsulinaemia in a cohort of 86 LIFE patients. Plasma adrenaline increased significantly from placebo treatment at baseline to year 1 of treatment (P<0.0001), and also during hyperinsulinaemia (P<0.0001). Plasma noradrenaline did not change significantly from placebo treatment at baseline to year 1, but increased significantly during hyperinsulinaemia both at baseline and at year 1 (P<0.0001 for both). There were no differences in plasma catecholamines or the relative changes between the two treatment arms at any stage. In a subset of 42 patients examined also at years 2 and 3, these findings were confirmed during long-term treatment. Thus, losartan had an effect on plasma catecholamines comparable to that with the beta-blocker atenolol in patients with hypertension and left ventricular hypertrophy at rest and during hyperinsulinaemia. We find it unlikely that a difference in sympathetic activity explains the outcome benefits of losartan over atenolol in the LIFE study.

Arterial wall thickness is associated with insulin resistance in type 2 diabetic patients

The aim of the present study was to investigate the independent association of the intimal-medial thickness of carotid and femoral arteries (CA-IMT and FA-IMT), a marker of atheroscelosis, with insulin resistance in type 2 diabetic patients. We evaluated CA-IMT and FA-IMT by high-resolution ultrasonography and insulin resistance determined by euglycemic hyperinsulinemic clamp in 119 type 2 diabetic subjects, 71 males and 48 females (age, 54 +/- 12 (SD) years). In simple regression analyses, CA-IMT and FA-IMT were significantly inversely correlated with insulin sensitivity index (CA-IMT, r = -0.225, p = 0.010; FA-IMT, r = -0.186, p = 0.043, respectively). Multiple regression analysis was performed with the logarithm of CA-IMT or FA-IMT as a dependent variable and insulin sensitivity index as an independent variable along with known clinical risk factors. Insulin sensitivity index exhibited a significant independent contribution to log (CA-IMT) (beta = -0.204, p = 0.033) and to log (FA-IMT) (beta = -0.237, p = 0.010) in these models (CA-IMT, R(2) = 0.347, p < 0.0001; FA-IMT, R(2) = 0.398, p < 0.0001, respectively). In conclusion, insulin resistance is associated with both CA-IMT and FA-IMT in type 2 diabetic patients, suggesting that it is an independent risk factor for the development of atherosclerosis in type 2 diabetes.

Is inappropriate left ventricular mass related to neurohormonal factors and/or arterial changes in hypertension? a LIFE substudy

We investigated whether inappropriately high left ventricular (LV) mass, defined as observed LV mass exceeding the level of individual LV mass predicted from gender, height, and stroke work, may be associated with an imbalance between growth-promoting and growth-inhibitory factors and/or structural vascular changes. In 53 patients with hypertension and electrocardiographic LV hypertrophy, 24-h ambulatory blood pressure (BP); echocardiographic LV mass, stroke volume and stroke work; minimal forearm vascular resistance (MFVR); and intima-media cross-sectional area in common carotid arteries (IMA) were evaluated after 2 weeks of placebo treatment. Serum insulin, plasma epinephrine, norepinephrine, endothelin, angiotensin II, aldosterone, and brain natriuretic peptide (BNP) were also measured. High observed LV mass was related to high IMA (r=0.46, P<0.001), MFVR (in men: r=0.36, P<0.05), 24-h ambulatory systolic BP (r=0.30, P=0.06), and lower plasma angiotensin II (r=-0.33, P<0.05), but not to other circulating growth factors. Stroke work was similarly related to IMA (r=0.42, P<0.01), MFVR (in men: r=0.41, P<0.05), and plasma angiotensin II (r=-0.32, P<0.05). Inappropriate LV mass, identified by the ratio between observed LV mass and the value predicted for gender, height, and stroke work, was not significantly related to any of the arterial or neurohormonal variables. In this small series of older hypertensive patients, inappropriate LV mass was not significantly related to arterial changes or to measured circulating growth factors, although weak relations cannot be excluded. Alternatively, inappropriately high LV mass might be related to unmeasured factors such as local myocardial alterations in growth factors and/or genetic predisposition to develop excessive LV hypertrophy.

Association between vascular dysfunction and reduced myocardial flow reserve in patients with hypertension: a LIFE substudy

Impaired myocardial flow reserve (MFR) has been demonstrated in hypertension, and has been associated with peripheral vascular changes. We investigated whether MFR was impaired and associated with structural and/or functional vascular changes in hypertensive patients without evidence of coronary artery disease (CAD). We measured left ventricular (LV) mass index by echocardiography and MFR by positron emission tomography in 33 unmedicated, hypertensive patients with electrocardiographic LV hypertrophy without CAD, and 15 age- and gender-matched normotensive subjects. We also measured 24-h ambulatory blood pressure, minimal forearm vascular resistance (MFVR) by plethysmography, media:lumen ratio in isolated, subcutaneous resistance arteries by myography, intima-media cross-sectional area of the common carotid artery, and flow-mediated (FMD) and nitroglycerin-induced dilatation (NID) of the brachial artery by ultrasound. Compared to the controls, the patients had impaired MFR (2.4 (95% CI 1.95-2.8) vs 3.4 (2.7-4.2), P<0.01) due to increased resting myocardial blood flow (MBF) (0.82 (0.73-0.91) vs 0.65 (0.56-0.75) ml/g min), and decreased dipyridamole-stimulated MBF (1.80 (1.55-2.1) vs 2.3 (1.80-2.8) ml/g min, both P<0.05). The difference in resting MBF disappeared (80 (74-87) vs 86 (74-97) microl/kg mmHg, NS) when normalized for blood pressure and heart rate. MFR correlated negatively to median 24-h systolic blood pressure (r=-0.50, P<0.01) as well as to LV mass index (r=-0.45, P<0.05) and MFVR in men (r=-0.47, P<0.05), and positively to FMD (r=0.44, P<0.05) and NID (r=0.40, P<0.05). Hypertensive patients with electrocardiographic LV hypertrophy without CAD had impaired MFR associated with cardiovascular hypertrophy and vasodilatory dysfunction. This suggests that MFR is impaired by LV hypertrophy and structural/functional vascular damage in the coronary and noncoronary circulation.

Insulin resistant young subjects at risk of accelerated atherosclerosis exhibit a marked reduction in peripheral endothelial function early in life but not differences in intima-media thickness

Reduced bio-availability of nitric oxide leading to disturbed flow mediated (endothelial dependent) vasodilation (FMD) has been shown to be an early functional abnormality of the vascular system in insulin resistant individuals and other subjects at high risk for accelerated atherosclerosis. In addition, an increase of the intima-media thickness (IMT) is regarded as an early marker of morphological alterations of the vessel wall. Whether endothelial dysfunction (ED) is evident already at an early stage when morphological changes of the vessel wall are not apparent is still an open question. We, therefore, examined IMT and peripheral endothelial function in a group of young insulin resistant subjects in a cross-sectional study and compared these results with a metabolically healthy (insulin sensitive) control group. We measured IMT (distal common carotid arteries), endothelium-dependent and endothelium-independent vasodilation (flow mediated and glyceroltrinitrate induced vasodilation of the brachial artery) non-invasively with high resolution ultrasound (13 MHz) in 91 young normoglycemic subjects (40/51 M/F, median: 31 years, range 18-50 years). Insulin sensitivity was measured with a euglycemic, hyperinsulinemic glucose clamp. Despite a marked reduction in flow-mediated vasodilation in insulin resistant (IR) subjects (FMD: median 3.4%, range -4.0 to 12.5 in IR versus 6.6%, range -1.2 to 20.1% in insulin sensitive subjects; P = 0.017), there was no difference in endothelial independent vasodilation (16.3%, range 5.7-41.0% versus 16.1%, range 0.5-39.2%) and in IMT (0.50 mm, range 0.39-0.66 and 0.51, 0.40-0.70 mm, respectively). These data suggest that ED can be detected very early in the life of insulin resistant subjects whereas no significant structural changes, indicated by a thickening of the intima-media layer, could be found. We therefore conclude that for identification of subjects with a high risk for accelerated atherosclerosis at an early stage, measurement of flow mediated vasodilation of the brachial artery may be more helpful than measuring thickness of the vascular wall.

Long-Term Effects of Irbesartan and Atenolol on the Renin-Angiotensin-Aldosterone System in Human Primary Hypertension

We examined long-term influence of the angiotensin II type 1-receptor blocker irbesartan and the beta1-adrenergic receptor blocker atenolol on some neurohormonal systems implicated in the pathophysiology of cardiac hypertrophy. Thus, 115 hypertensive patients with left ventricular hypertrophy were randomized to receive double-blind irbesartan or atenolol, with additional therapy if needed. Neurohormone measurements and echocardiography were performed at weeks 0, 12, 24, and 48. Left ventricular mass was reduced more by irbesartan than by atenolol (-26 g/m2 versus -14 g/m2, P = 0.024), despite similar reductions in blood pressure. Plasma renin activity and angiotensin II increased (P < 0.001) by irbesartan (0.9 +/- 0.7 to 3.4 +/- 4.2 ng/mL x h, and 3.0 +/- 1.6 to 13.0 +/- 17.7 pmol/L), but decreased (P < 0.01) by atenolol (1.0 +/- 0.6 to 0.7 +/- 0.6 ng/mL x h, and 3.4 +/- 1.6 to 3.2 +/- 2.2 pmol/L). Serum aldosterone decreased (P < 0.05) by both irbesartan (346 +/- 140 to 325 +/- 87 pmol/L) and atenolol (315 +/- 115 to 283 +/- 77 pmol/L). Changes in left ventricular mass by irbesartan related inversely to changes in plasma renin activity, angiotensin II, and aldosterone (all P < 0.05). Plasma levels and 24-hour urinary excretions of catecholamines, plasma leptin, proinsulin, insulin and insulin sensitivity remained largely unchanged in both groups. Thus, the renin-angiotensin aldosterone system appears to be an important non-hemodynamic factor in the regulation of left ventricular mass.

Are left ventricular mass, geometry and function related to vascular changes and/or insulin resistance in long-standing hypertension? ICARUS: a LIFE substudy

Vascular hypertrophy and insulin resistance have been associated with abnormal left ventricular (LV) geometry in population studies. We wanted to investigate the influence of vascular hypertrophy and insulin resistance on LV hypertrophy and its function in patients with hypertension. In 89 patients with essential hypertension and electrocardiographic LV hypertrophy, we measured blood pressure; insulin sensitivity by hyperinsulinaemic euglucaemic clamp; minimal forearm vascular resistance (MFVR) by plethysmography; intima-media cross-sectional area of the common carotid arteries (IMA) by ultrasound; and LV mass, relative wall thickness (RWT), systolic function and diastolic filling by echocardiography after two weeks of placebo treatment. LV mass index correlated to IMA/height (r=0.36, P=0.001), serum insulin (r=-0.25, P<0.05), plasma glucose (r=-0.34, P<0.01), and showed a tendency towards a correlation to insulin sensitivity (r=0.21, P=0.051), but was unrelated to MFVR. Deceleration time of early diastolic transmitral flow positively correlated to IMA/height (r=0.30, P<0.01). The ratio between early and atrial LV filling peak flow velocity negatively correlated to MFVR(men) (r=-0.30, P<0.05). Endocardial and midwall systolic LV function were not related to vascular hypertrophy, plasma glucose, serum insulin or insulin sensitivity. In conclusion, insulin resistance was not related to LV hypertrophy or reduced LV function. However, high thickness of the common carotid arteries was associated with LV hypertrophy and high deceleration time of early diastolic transmitral flow. High MFVR was associated with low ratio between early and atrial LV filling peak flow velocity. This may suggest that systemic vascular hypertrophy contributes to abnormal diastolic LV relaxation in patients with hypertension and electrocardiographic LV hypertrophy.

Is cardiovascular remodeling in patients with essential hypertension related to more than high blood pressure? A LIFE substudy. Losartan Intervention For Endpoint-Reduction in Hypertension

BACKGROUND

Blocking the renin-aldosterone-angiotensin II system has been hypothesized to induce blood pressure-dependent as well as blood pressure-independent regression of cardiovascular hypertrophy. However, the relative influence of elevated blood pressure (BP) and various neurohormonal factors on cardiovascular remodeling in hypertension is unclear.

METHODS

In 43 untreated patients with hypertension with electrocardiographic left ventricular hypertrophy, we measured relative wall thickness and left ventricular mass index by echocardiography and by magnetic resonance imaging (n = 32), intima-media cross-sectional area, and distensibility of the common carotid arteries by ultrasound, media/lumen ratio of isolated subcutaneous resistance arteries by myography, and median 24-hour systolic BP (n = 40), serum insulin, and plasma levels of epinephrine, norepinephrine, renin, angiotensin II, aldosterone, and endothelin.

RESULTS

In multiple regression analyses, left ventricular mass index by echocardiography (R2 = 0.14, P <.05) and by magnetic resonance imaging (R2 = 0.32, P =.001) were associated with 24-hour systolic BP, whereas relative wall thickness was associated with plasma epinephrine (R2 = 0.12, P <.05) and aldosterone (R2 = 0.10, P <.05). Intima-media cross-sectional area/height was associated with 24-hour systolic BP (beta = 0.40) and plasma epinephrine (beta = 0.43) (adjusted R2 = 0.32, P <.001), whereas carotid distensibility was associated with 24-hour systolic BP (beta = 0.40) and plasma angiotensin II (beta = -0.41) (adjusted R2 = 0.30, P <.001). Media/lumen ratio in subcutaneous resistance arteries was associated with plasma epinephrine (R2 = 0.22, P <.01).

CONCLUSION

Apart from being associated with a high BP burden, cardiovascular remodeling was associated with high levels of circulating epinephrine, aldosterone, as well as angiotensin II, suggesting a beneficial effect above and beyond the effect of BP reduction when using antihypertensive agents blocking the receptors of these neurohormonal factors.

Vasodilatory capacity and vascular structure in long-standing hypertension: a LIFE substudy. Losartan Intervention For Endpoint-Reduction in Hypertension

BACKGROUND

Flow-mediated dilatation (FMD), which is considered a measure of endothelial function, has been found impaired in hypertension. However, it is unclear whether this impairment is explained solely by endothelial dysfunction, or whether it is associated with structural vascular changes and reduced vasodilatory capacity.

METHODS

In 42 unmedicated patients with hypertension and electrocardiographic left ventricular hypertrophy, we measured the following: 24-h ambulatory blood pressure (BP), minimal forearm vascular resistance (MFVR) by plethysmography, intima-media cross-sectional area of the common carotid arteries (IMA), FMD, and nitroglycerin-induced dilatation (NID) in the brachial artery by ultrasound.

RESULTS

We found that FMD was correlated positively with NID (r = 0.38, P < .05). However, FMD as well as NID correlated negatively to 24-h systolic BP (r = -0.41, P = .01 and r = -0.52, P = .001), IMA/height (r = -0.41, P < .01 and r = -0.53, P < .001) and MFVR(men) (r = -0.44, P < .05 and r = -0.42, P < .05).

CONCLUSIONS

Low FMD as well as low NID were related in parallel to high systolic BP and to the severity of vascular changes in different vascular beds, suggesting that elevated BP load in hypertension induces parallel abnormalities in conduit artery structure and overall vasodilatory capacity. Therefore, the decrease in FMD observed in severe hypertension may be caused by endothelial dysfunction as well as by structural vascular changes, suggesting difficulties in interpreting FMD solely as a measure of endothelial dysfunction in hypertensive patients with left ventricular hypertrophy.

Intima-media thickness: a new tool for diagnosis and treatment of cardiovascular risk

Increased intima-media thickness (IMT) is a non-invasive marker of early arterial wall alteration, which is easily assessed in the carotid artery by B-mode ultrasound, and more and more widely used in clinical research. Methods of IMT measurement can be categorized by two approaches: (i) measurement at multiple extracranial carotid sites in near and far walls and (ii) computerized measurement restricted to the far wall of the distal common carotid artery. Because IMT reflects global cardiovascular risk, its normal value might be better defined in terms of increased risk rather than in terms of statistical distribution within a healthy population. The available epidemiological data indicate that increased IMT (at or above 1 mm) represents a risk of myocardial infarction and/or cerebrovascular disease. Close relationships have been shown between: (i) most traditional cardiovascular risk factors; (ii) certain emerging risk factors such as lipoproteins, psychosocial status, plasma viscosity, or hyperhomocysteinemia; and (iii) various cardiovascular or organ damages such as white matter lesion of the brain, left ventricular hypertrophy, microalbuminuria or decreased ankle to brachial systolic pressure index. Thus, IMT gives a comprehensive picture of the alterations caused by multiple risk factors over time on arterial walls. Prospective primary and secondary prevention studies have also shown that increased IMT is a powerful predictor of coronary and cerebrovascular complications (risk ratio from 2 to 6) with a higher predictive value when IMT is measured at multiple extracranial carotid sites than solely in the distal common carotid artery. Therapeutic double-blind trials have shown that lipid-lowering drugs, such as resin and overall statines, and to a lesser extent antihypertensive drugs, such as calcium antagonists, may have a beneficial effect on IMT progression in asymptomatic or in coronary patients. However, methodological standardization of IMT measurement still needs to be implemented before routine measurement of IMT can be proposed in clinical practice as a diagnostic tool for stratifying cardiovascular risk in primary prevention and for aggressive treatment decision. It can be anticipated however, that the presence of increased carotid IMT in one individual with intermediate cardiovascular risk would lead to his classification into the high-risk category and thus influence the aggressiveness of risk factor modifications.

Effects of troglitazone and temocapril in spontaneously hypertensive rats with chronic renal failure

OBJECTIVE

The insulin resistance state is common in humans and animals with chronic renal failure. We investigated the effects of troglitazone, an insulin sensitizer, on blood pressure and nephropathy in the remnant kidney model of spontaneously hypertensive rats (SHR).

METHODS

Eight-week-old male SHR were subjected to five-sixth nephrectomy. At the age of 10 weeks, the rats were randomly allocated to groups that received troglitazone (70 mg/kg per day); the angiotensin converting enzyme inhibitor temocapril (10 mg/kg per day); troglitazone (70 mg/kg per day) plus temocapril (10 mg/kg per day), or a vehicle alone as an untreated control group. Systolic blood pressure (SBP) and urinary protein excretion were measured every 2 weeks. At the age of 22 weeks, biochemical measurements and histological examination were performed.

RESULTS

Blood glucose, glycosylated hemoglobin and body weight were similar in the four groups. SBP, serum creatinine and glomerular sclerosis index were significantly reduced in all treated groups compared with those in the control group. Urinary protein excretion, glomerular volume and aortic media thickness were significantly decreased in temocapril-treated rats and troglitazone plus temocapril-treated rats compared with those in control rats. Although antihypertensive effects of troglitazone were minute compared with those of temocapril or troglitazone plus temocapril, there was no significant difference between the glomerular sclerosis indices in these three drug-treated groups.

CONCLUSIONS

The results suggest that troglitazone has renoprotective effects in this rat model. These effects might be due to the inhibition of growth factors rather than to the minute hypotensive effect, although the mechanism remains to be elucidated.

Effects of antihypertensive therapy on hypertensive vascular disease

Hypertension is associated with alterations in the structure, function, and mechanical properties of large and small arteries. Changes in the endothelium, smooth muscle cell, extracellular matrix, and possibly the adventitia, contribute to complications of hypertension. In large arteries, vascular hypertrophy is found, often with increased stiffness of media components. In small arteries, particularly in mild hypertension, rearrangement of smooth muscle cells around a smaller lumen without changes in media volume (eutrophic remodeling) occurs; in more severe hypertension, hypertrophic remodeling with increased vascular stiffness can be found. Vascular remodeling is accompanied by an increase in the extracellular matrix, particularly collagen deposition. Recent studies have demonstrated that vascular remodeling and endothelial dysfunction of small and large vessels may be normalized by treatment with some antihypertensive agents (angiotensin converting enzyme inhibitors, angiotensin AT(1) receptor antagonists, and long-acting calcium channel blockers). Angiotensin converting enzyme inhibitors have now been shown to improve outcomes in hypertensive patients, an effect that may in part be related to the vascular protective effects reviewed here.