BackgroundIsolated systolic hypertension (ISH) of the young has been associated with both normal and increased cardiovascular risk, which has been attributed to differences in central systolic blood pressure and arterial stiffness.MethodsWe assessed the prevalence of ISH of the young and compared differences in central systolic blood pressure and arterial stiffness between ISH and other hypertensive phenotypes in a multi-ethnic population of 3744 subjects (44% men), aged <40 years, participating in the HELIUS study.ResultsThe overall prevalence of ISH was 2.7% (5.2% in men and 1.0% in women) with the highest prevalence in individuals of African descent. Subjects with ISH had lower central systolic blood pressure and pulse wave velocity compared with those with isolated diastolic or systolic-diastolic hypertension, resembling central systolic blood pressure and pulse wave velocity values observed in subjects with high-normal blood pressure. In addition, they had a lower augmentation index and larger stroke volume compared with all other hypertensive phenotypes. In subjects with ISH, increased systolic blood pressure amplification was associated with male gender, Dutch origin, lower age, taller stature, lower augmentation index and larger stroke volume.ConclusionISH of the young is a heterogeneous condition with average central systolic blood pressure values comparable to individuals with high-normal blood pressure. On an individual level ISH was associated with both normal and raised central systolic blood pressure. In subjects with ISH of the young, measurement of central systolic blood pressure may aid in discriminating high from low cardiovascular risk.
The arterial baroreflex regulates blood pressure by modifying heart rate and systemic vascular resistance. Baroreflex sensitivity is expressed as the relation between changes in blood pressure and the resulting changes in reciprocal values of heart rate (cardBRS) and in reciprocal values of vascular resistance (vascBRS). This study investigated determinants of vascBRS and cardBRS and their relationship in a random population sample. Continuous noninvasive arterial pressure was analyzed in 105 adults (43 males) with a median age of 45 (range 18-95) years and body mass index of 24.5 (range 18.1-39.1) kg m⁻². Systolic and diastolic blood pressures were 130 (range 95-205) and 80 (range 47-141) mmHg, and heart rate was 66 (range 42-109) beats min⁻¹. Pulse contour (CO-trek)-determined vascular resistance was 1.37 (range 0.60-7.75) mmHg s ml⁻¹. The results of vascBRS and cardBRS were log-transformed; linear regression analysis revealed that age, resistance⁻¹, systolic and diastolic blood pressures were major determinants of log(vascBRS) explaining 30.5 % of the variance. Determinants of log(cardBRS) were age, body mass index, heart rate, systolic and diastolic blood pressures, explaining 70.4 % of the variance. Thus, some established determinants of cardBRS were not correlated with vascBRS. There was no correlation between log(cardBRS) and log(vascBRS) after correction for age, supporting that vascBRS is an independent description of baroreflex regulation. These findings suggest that vascBRS and cardBRS report different modalities of cardiovascular autonomic function.
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