Gender-related differences in adolescent hypertension and in target organ effects.

AIMS: To assess whether a gender difference exists in adolescent hypertension and its target organ damage and to compare potential confounding factors and target organ damage in hypertensive and normotensive adolescent girls. METHODS: From the Debrecen Hypertension Study, the anthropometric, blood pressure, and laboratory data as well as intima-media thickness (IMT) and left ventricular mass index (LVMI) of 58 hypertensive boys, 56 hypertensive girls, and 30 normotensive girls were analyzed. RESULTS: Both systolic and mean blood pressure values were higher in adolescent hypertensive boys than in girls. This difference was also present when comparing 24-hour average blood pressure values. Plasma concentrations of nitric oxide (NO) and endothelin-1 were not different in the two gender groups. IMT of the carotid arteries were similar in hypertensive boys and girls, but a significantly higher LVMI was detected in boys. A significant difference was detected in anthropometric data (height, weight, and body mass index [BMI]), plasma concentration of NO (lower levels in hypertensives), and IMT in hypertensive and normotensive girls (higher IMT in hypertensive girls). CONCLUSIONS: There is a difference between the severity of hypertension between hypertensive adolescent girls and boys. Hypertensive girls differ from normotensive girls not only in blood pressure values but also in risk factors and subclinical target organ effects. Further studies are needed to explain the gender differences in adolescent hypertension. The potential role of sex hormones in hypertensive teenagers also needs to be clarified in future works.

Carotid intima-media thickness and cerebrovascular reactivity in long-term type 1 diabetes mellitus.

PURPOSE: Diabetes mellitus (DM) is one of the leading risk factors for cerebrovascular diseases. Both macro- and microvascular damage may occur. The aim of the present work was to assess intima-media thickness as well as cerebral vasoreactivity in patients suffering from type 1 diabetes mellitus (IDDM). METHODS: Intima-media thickness and resting middle cerebral artery blood flow velocity was measured in 33 IDDM patients and 31 healthy controls. After baseline investigations, 30 seconds of breath holding (BH) and 60 seconds of voluntary hyperventilation (HV) were performed by the subjects. Transcranial Doppler measurements were performed in each case after vasodilatory (BH) and vasoconstrictor (HV) stimuli. Cerebrovascular reactivity was expressed as the percentage of change of the middle cerebral mean blood flow velocity after BH or HV. RESULTS: IDDM patients showed a significantly larger intima-media thickness (0.1 +/- 0.02 mm) than healthy controls (0.06 +/- 0.006 mm, p < 0.001). Cerebrovascular reactivity after BH was less intensive in diabetic patients (19.3 +/- 16.1%) than that of the control subjects (38.7 +/- 22.8%, p < 0.01). Similarly, HV induced a less-pronounced decrease of cerebral blood flow velocity in diabetic subjects (-30.1 +/- 13.2%) than in nondiabetics (-37.6 +/- 17.0%, p < 0.05). CONCLUSION: Our results refer to early macro- and microangiopathic involvement of the cerebral vessels, which develop in parallel with angiopathies of the other organs, such as nephropathy and retinopathy. Further prospective studies are needed to clarify the role of these macro- and microangiopathic changes in the development of cerebrovascular complications in patients suffering from DM.

Hyperventilation-induced cerebrovascular reactivity among hypertensive and healthy adolescents.

BACKGROUND: It is known that cerebral vasoreactivity is altered in adult arterial hypertension but no information is available about cerebral arteriolar function in hypertensive adolescents. Therefore, the aim of the present work was to assess cerebral vasoreactivity responses in adolescent hypertension. METHODS: 113 hypertensive and 58 normotensive adolescents were assessed with transcranial Doppler sonography by using voluntary hyperventilation (HV) as vasoconstrictory stimulus. Absolute blood flow velocities (systolic, mean and diastolic) and pulsatility indices (PIs) at rest and after HV, as well as percentage change of the blood flow velocities after HV were compared among the groups. RESULTS: Blood flow velocities at rest were significantly higher in hypertensive individuals, while PIs were similar in the two groups. After HV, all blood flow velocity parameters were higher among hypertensive teenagers than in healthy controls, while PIs did not differ between the two groups. Taking the relative changes after HV into account, it was found that HV induced a more pronounced change of the systolic and mean blood flow velocities of the control subjects than in hypertensive adolescents. CONCLUSIONS: Cerebrovascular reactivity to hypocapnia is decreased in hypertensive adolescents as compared to healthy teenagers. Further studies are needed to clarify the clinical significance of altered cerebral microvascular function in adolescent hypertension.

Both nitric oxide and endothelin-1 influence cerebral blood flow velocity at rest and after hyper- and hypocapnic stimuli in hypertensive and healthy adolescents.

BACKGROUND AND PURPOSE: Nitric oxide (NO)/endothelin imbalance may play a role in the regulation of cerebral blood flow. The aim of the present study was to assess whether these endothelial factors influence middle cerebral artery blood flow velocities (MCAV) and cerebrovascular reactivity (CVR) in healthy and hypertensive adolescents. SUBJECTS AND METHODS: 106 adolescents (61 hypertensive and 45 normotensive) underwent transcranial Doppler measurements of the middle cerebral artery at rest and after 30 s of breath-holding (BH) and 60 s of hyperventilation (HV). Additionally, NO and endothelin-1 (ET-1) concentrations of the serum were assessed. The correlation between NO and ET-1 levels as well as MCAV and CVR values was analyzed. RESULTS: Resting MCAVs were higher among hypertensive teenagers (76.5 +/- 24 vs. 62.8 +/- 15.6 cm/s, respectively, p < 0.001). CVR values did not differ between hypertensive and healthy adolescents after the BH and HV procedure. A significant negative correlation was found between absolute MCAV values and NO concentrations. ET-1 was positively related to MCAV. CONCLUSIONS: Cerebral blood flow velocities, but not CVR values, are associated with serum NO and ET-1 concentrations in adolescents.

Target-organ damage in adolescent hypertension. Analysis of potential influencing factors, especially nitric oxide and endothelin-1.

BACKGROUND AND PURPOSE: To assess the role of the nitric oxide-endothelin imbalance in the development of target-organ damages (carotid intima-media thickness and left ventricular mass index) in adolescent hypertension. METHODS: 125 adolescents--67 hypertensive and 58 normotensive--underwent routine anthropology (height, weight) and blood pressure measurements, and laboratory (glucose, cholesterol and triglyceride levels) testing as well as sampling blood for determination of the plasma concentrations of nitric oxide (NOx) and endothelin-1 (ET-1), followed by measurement of the carotid intima-media thickness (IMT) and left ventricular mass index (LVMI). RESULTS: Plasma concentration of NOx was significantly lower (27.7+/-13.7 vs. 35.8+/-7.0 micromol/l, respectively, p<0.001) and ET-1 was higher (3.11+/-3.9 vs. 1.09+/-1.07 fmol/ml, respectively, p<0.001) in hypertensive adolescents than that of controls. NOx negatively, endothelin positively correlated with blood pressure values, especially with systolic BP. An inverse relationship has been found between NOx and ET-1 concentrations (r=-0.29, p<0.003). In this adolescent population body weight, systolic blood pressure and plasma ET-1 were the most important factors influencing IMT, whereas LVMI correlated with height and weight and systolic BP of the teenagers. CONCLUSIONS: NO/endothelin imbalance seems to play a role in the development of hypertension and target-organ damages in adolescence. Further studies are encouraged in order to clarify the pathophysiological role of NO/endothelin imbalance in adolescent hypertension.

Angiotensin-converting enzyme gene polymorphism, carotid intima-media thickness, and left ventricular mass index in adolescent hypertension.

PURPOSE: The aim of this study was to determine whether a positive correlation exists between the DD genotype of angiotensin-converting enzyme (ACE) and the carotid intima-media thickness (IMT) or left ventricular mass index (LVMI) in adolescents with hypertension. METHODS: We studied 120 hypertensive and 58 normotensive (control) adolescents. ACE gene polymorphism was determined by a standardized method. The IMT was measured in the common carotid arteries, and the LVMI was calculated on transthoracic echocardiography. The severity of hypertension was graded according to the results of ambulatory blood pressure monitoring as white coat, borderline, or proven hypertension. The association between ACE gene polymorphism and the obtained parameters was analyzed using analysis of variance and chi-square testing. RESULTS: Both the IMT and LVMI were higher in hypertensive than in control adolescents. In hypertensive subjects, no relationship was found between the different ACE genotypes and the IMT: the mean (+/- standard deviation) IMT in patients with the DD genotype was 0.57 +/- 0.11 mm; in those with the DI genotype, 0.53 +/- 0.01 mm; and in those with the II genotype, 0.55 +/- 0.01 mm. The LVMI was also similar in all 3 ACE genotypes: DD, 106.7 +/- 32.3 g/m(2); DI, 102.2 +/- 38.1 g/m(2); and II, 103.2 +/- 26.3 g/m(2). The severity of hypertension as assessed by ambulatory blood pressure monitoring was independent of the ACE genotype. CONCLUSIONS: Target-organ damage (left ventricular hypertrophy and carotid atherosclerosis) is detectable in adolescents with hypertension and, in those subjects, ACE genotype polymorphism is not correlated with the severity of target-organ damage as measured by IMT and LVMI.

[Assessment of cerebrovascular reactivity using the breath-holding test in hypertensive and normotensive adolescents--preliminary results]. / A cerebrovascularis reaktivitás vizsgálata légzés-visszatartásos teszttel hypertoniás és egészséges serdülókben (elózetes eredmények).

AIM: Authors report on preliminary results of cerebral vasoreactivity-tests performed in frame of the Debrecen Hypertension Study among hypertensive and healthy adolescents. METHODS: Investigators measured blood flow velocities before and after 30 seconds of breath holding using transcranial Doppler sonography. RESULTS: Blood flow velocities at rest were significantly higher in the hypertensive that in the healthy adolescent group. Breath holding induced less intensive cerebral vasoreactivity response in the hypertensive than in the normotensive group. CONCLUSION: It is concluded that altered arteriolar function of the cerebral arterioles can be detected already in this early stage of hypertension.

Cerebrovascular reactivity in hypertensive and healthy adolescents: TCD with vasodilatory challenge.

BACKGROUND: Adolescent hypertension predicts hypertension and increased cardiovascular morbidity in adulthood. The aim of the present work was to test whether cerebrovascular reactivity to CO2 is altered among hypertensive adolescents. METHODS: From the population-based cohort of the Debrecen Hypertension Study, 113 hypertensive and 58 normotensive adolescents underwent transcranial Doppler measurements at rest and after 30 seconds of breath holding. RESULTS: Systolic, mean, and diastolic blood flow velocities were higher among hypertensive individuals at rest. Taking the absolute blood flow velocity parameters into account, after breath holding, only the pulsatility index was significantly higher in the hypertensive group. The percentage change of the different blood flow parameters showed less intensive change in hypertensive teenagers. CONCLUSION: Cerebral vasoreactivity is decreased among hypertensive individuals as compared to healthy controls.

Increased common carotid artery intima media thickness in adolescent hypertension: results from the Debrecen Hypertension study.

BACKGROUND: The aim of the present work was to investigate intima media thickness (IMT) in healthy and in hypertensive adolescents and its influencing factors. METHODS: 103 hypertensive and 58 healthy adolescents were studied. IMT was measured in the common carotid artery using B-mode ultrasonography. Additionally, laboratory parameters (blood glucose, cholesterol, triglycerides, HDL- and LDL-cholesterols) and left ventricular mass indices were obtained. RESULTS: IMT in the common carotid artery was higher in hypertensive adolescents (means +/- SD: 0.55 +/- 0.11 mm) than in healthy control subjects (0.48 +/- 0.08 mm, p < 0.001). Similarly, a higher left ventricular mass index was measured in hypertensive (103.2 +/- 30.6 g/m(2)) than in healthy teenagers (91.1 +/- 25.2 g/m(2), p < 0.001). In general, IMT in adolescents was associated with age, weight, body mass index, left ventricular mass index and average systolic and diastolic blood pressure values of the subjects. By assessing the multivariate association between IMT and other factors, intima-media thickness was only associated with age and left ventricular mass index of the hypertensive subjects and was independent from all the investigated factors in normotensive controls. CONCLUSIONS: Our data suggest an ongoing target-organ damage in adolescent hypertension. These patients need to be subjected to early diagnostic methods, treatment and a regular follow-up, in order to avoid severe clinical manifestations of secondary target-organ damage due to hypertension.

Transcranial Doppler study of the cerebral hemodynamic changes during breath-holding and hyperventilation tests.

BACKGROUND AND PURPOSE: The aim of the present study was to assess the time course of hyperventilation (HV) and breath-holding (BH) tests in healthy volunteers. SUBJECTS AND METHODS: Young healthy volunteers (n = 29) underwent continuous registration of the middle cerebral artery mean blood flow velocity (MCAV) during and after 30 seconds of BH and 60 seconds of HV. Absolute values as well as percentage changes of the MCAV are reported. In 13 subjects, determination of capillary blood gas parameters (pH, pCO2, pO2, and O2 saturation) was performed before tests, after BH and after HV. RESULTS: MCAV during 30 seconds of breath-holding starts to increase after 10 seconds and reaches its highest level at 30 seconds. After breathing normally, MCAV normalizes within 30 seconds. Hyper-ventilation results in a decrease in MCAV, which reaches a plateau at 20 to 30 seconds after starting to hyperventilate, and blood flow velocity did not change significantly any further until the end of the procedure. The normalization of the MCAV is incomplete at 30 seconds after finishing hyperventilation. None of the capillary blood gases changed significantly after breath-holding, whereas capillary pH, pO2, and oxygen saturation increased and pCO2 decreased after hyperventilation. No relationship was found between capillary blood gas parameters and MCAV values. CONCLUSIONS: The authors concluded that breath-holding and hyperventilation tests seem to be a practical alternative to acetazolamide and the CO2 inhalation method in the assessment of cerebral hemodynamics.

Assessment of cerebrovascular reserve capacity in asymptomatic and symptomatic hemodynamically significant carotid stenoses and occlusions.

BACKGROUND: Cerebrovascular reactivity measurements are believed to be a helpful tool for selecting patients who are at higher risk for hemodynamic strokes. The aim of this study was to compare cerebral vasoreactivity among patients suffering from internal carotid artery stenosis of different severity (asymptomatic stenosis, asymptomatic occlusion, symptomatic stenosis, symptomatic occlusion). METHODS: Sixty-two patients with asymptomatic and symptomatic internal carotid artery stenoses and occlusions underwent transcranial Doppler-acetazolamide tests. Absolute velocities of the middle cerebral arteries (MCAV), percent increases of the MCAV at different time points of the test (cerebrovascular reactivity, CVR) and maximal percent increase after administration of acetazolamide (cerebrovascular reserve, CRC) were compared on the affected and non-affected sides. Asymmetry indices (CRC (affected side)/CRC (non-affected side)) were compared between the groups of different severity of obstructive lesion. RESULTS: Resting MCAV was similar on both sides in all groups. A significant side-difference of the MCAV values after acetazolamide was observed only in the symptomatic groups. Difference of cerebrovascular reserve capacity between the affected and non-affected side was statistically significant only in the symptomatic groups (CRC symptomatic stenosis 36.6 +/- 20.9% vs. 71.1 +/- 27.9%, CRC symptomatic occlusion: 31.2 +/- 24.6% vs. 64.5 +/- 29.7%). Asymmetry index of the CRC was near to 1 in the asymptomatic stenosis group only, while in all the other groups this index referred to a significant hemispheric asymmetry of the vasoreactivity. CONCLUSIONS: Although in general cerebrovascular reserve capacity is compromised in cases of hemodynamically significant carotid lesions, there is a large individual variability within the subgroups. Further randomized studies are needed to clarify whether the clinical efficiency of carotid endarterectomy and extra-intracranial bypass may be improved by selecting the patients using hemodynamic criteria.