CARDIOVASCULAR AUTONOMIC REGULATION IN SUBJECTS WITH NORMAL BLOOD PRESSURE, HIGH–NORMAL BLOOD PRESSURE and RECENT‐ONSET HYPERTENSION

Abstract

1. In the present study, we tested the hypothesis that heart rate variability (HRV) is reduced in recent-onset hypertension and that pressor responses to standard autonomic reflex tests are not any different in hypertensives compared with normotensives. We also hypothesized that subjects with high-normal blood pressure (BP) would be distinguishable from normotensives on the basis of short-term HRV indices. 2. Three groups of subjects, each consisting of 15 men and 10 women, were examined. The first group consisted of subjects with recent-onset hypertension who were not taking antihypertensive medication (mean (+/-SD) age 50 +/- 12 years; BP >/= 140/90 mmHg), the second group consisted of subjects with high-normal BP (mean age 46 +/- 13 years; BP 130-139/85-89 mmHg) and the third group consisted of subjects with normal BP (mean age 48 +/- 12 years; BP < 120/80 mmHg). The aim was to characterize the autonomic state in each group. 3. Blood pressure, heart rate (HR), indices of short-term HRV during supine rest and quiet standing, HR variation during timed deep breathing (HRVdb) and pressor responses to the cold pressor test and sustained isometric handgrip were compared between the groups. 4. Although the three groups were comparable (P > 0.1) in terms of mean HR and low-frequency (LF) power expressed in normalized units at rest and during quiet standing, the standard deviation of normal-to-normal RR intervals (SDNN) during supine rest, LF and high-frequency spectral powers during supine rest and HRVdb were lowest in hypertensives (P </= 0.05 for each), indicating diminished baroreflex modulation of RR intervals in hypertensives. 5. In contrast, LF power was highest in subjects with high-normal BP (P </= 0.05) during supine rest and this is possibly because of higher BP variability. 6. The results suggest that HRVdb provides a simple measure of cardiac vagal effects in hypertensives, the rate-pressure product provides a simple measure of overall HRV in hypertensives and, in clinical hypertension, the arterial baroreflex mechanism is reset to maintain a higher BP through diminished vagal modulation of HR and possibly heightened sympathetic outflow to the heart and resistance vessels.

Exaggerated exercise pressor reflex in adults with moderately elevated systolic blood pressure: role of purinergic receptors

“…This is consistent with our previous study in stage I hypertensive adults indicating exaggerated neurocirculatory responses to graded intensities of isolated metaboreflex activation (11). Previous studies have reported that the pressor response to exercise in adults with high-normal systolic BP is not different than the response in NTN adults (21,50). This is somewhat contradictory to the findings of the present investigation; however, such differences are likely a result of differing inclusion criteria and BP classifications.…”

Epidemiological Study on the Effect of Pre-Hypertension and Family History of Hypertension on Cardiac Autonomic Function

“…The higher the blood pressure, the greater the chance of heart attacks, heart failure, stroke, and kidney disease in subjects with a blood pressure ranging from 115/75 to 185/115 mm Hg (19). There has been a hospital-based study of CAF in subjects with high-normal blood pressure of 130 to 139/85 to 89 mm Hg (20), rather than the revised value of 120 to 139/80 to 89 mm Hg. The findings of CAF alteration in normotensive subjects with a family history of hypertension (FHH) have been inconsistent (21)(22)(23), and these studies define normotension as a blood pressure Ͻ140/90 mm Hg (21)(22)(23), not the revised value of Ͻ120/80 mm Hg.…”

Efeito de esmolol sobre o intervalo QT corrigido e alterações da dispersão do intervalo QT corrigido observadas durante a indução da anestesia em pacientes hipertensos que receberam um inibidor da enzima conversora de angiotensina

“…7 A alteração da homeostase cardiovascular em pacientes hipertensos mostrou causar um desequilíbrio simpatovagal caracterizado pela diminuição da modulação vagal e pelo aumento da atividade simpática. 8 A resposta à laringoscopia é significativamente diferente em pacientes hipertensos, em comparação com pacientes normotensos. As alterações da pressão arterial que se desenvolvem imediatamente após a indução da anestesia são muito maiores em pacientes hipertensos.…”