Altered Baroreflex Sensitivity in Young Women with a Family History of Hypertension.

A positive family history of hypertension (+FH) is a risk factor for the future development of hypertension. Hypertension is associated with reductions in baroreflex sensitivity (BRS). Therefore, we hypothesized that young women with a +FH (n=12, 22±1 yrs, BMI 21±1 kg/m2, MAP 79±1 mmHg) would have lower BRS compared to young women without a family history of hypertension (-FH) (n=13, 22±1 yrs, BMI 21±1 kg/m2, MAP 77±2 mmHg, all P>0.05 between groups). Continuous measurements of muscle sympathetic nerve activity (MSNA), blood pressure, and electrocardiogram derived R-R interval were recorded at rest and during a Valsalva maneuver. Both cardiovagal and vascular sympathetic BRS were assessed. Resting cardiovagal BRS was reduced in the +FH women (all sequences: -FH 32.3±3.7 vs. +FH 20.2±2.9 ms/mmHg, P = 0.02). Cardiovagal BRS during phase IV (-FH 16.5±2.7 vs. +FH 7.6±1.3 ms/mmHg, P < 0.01) but not phase II (-FH 5.5±0.9 vs. +FH 5.0±0.8 ms/mmHg, P = 0.67) of the Valsalva maneuver was also lower in the +FH women. Vascular sympathetic BRS at rest (-FH -2.38±0.7 vs. +FH -2.33±0.3 bursts/min/mmHg, P = 0.58) and during the Valsalva (-FH -0.74±0.23 vs. +FH -0.66±0.18 bursts/15s/mmHg, P = 0.79) were not different between groups. These data suggest that healthy young women with a positive family history of hypertension have reduced cardiovagal BRS. This may be one mechanism contributing to the increased incidence of hypertension in this population later in life.