Determinants of vascular and cardiac baroreflex sensitivity values in a random population sample

Abstract

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.

Time domain measurement of the vascular and myocardial branches of the baroreflex: A study in physically active versus sedentary individuals

“…Estimates of effectiveness of the vasomotor and myocardial branches (both for SV and PEP) were also positively associated. These results replicate the partial redundancy in the baroreflex loops found by Vaschillo et al () and are contrary to the results of Borgers et al () who did not find associations between sensitivity in the cardiac and vasomotor branches of the baroreflex.…”

“…Greater vBEI was associated with lower TPR. It is worth noting that, in the Borgers et al () study using the Nexfin CO‐trek pulse contour method, no association between sensitivity in the vasomotor baroreflex and TPR was observed. However, they used diastolic BP as the probe to the baroreflex whereas we used SBP.…”

“…The determination of the time delays between SBP and the output measures (duration of lags of beats between pairs of values) is a question of particular relevance for the computation of reflex sequences in this time domain analysis. The cardiac baroreflex is modulated by fast vagal influences of very short latency that can be manifested in the same IBI, while the vasomotor and myocardial branches are modulated by sympathetic cardiac control, which is slower in inducing its physiological effects (Borgers et al, ). The neurokinetics of norepinephrine compared to acetylcholine and the slow conduction velocities in the sympathetic fibers have to be considered.…”

“…For this purpose, the Nexfin CO‐trek pulse contour method has been applied to the analysis of continuous finger BP to derive an indirect measure of SV, and thus calculate a surrogate of total peripheral resistance (TPR). Recently, Borgers et al () have applied this method to assess the sensitivity of the vasomotor baroreflex through cross‐correlation analysis in healthy young individuals. Previous assessments of the myocardial branch have used cross‐spectral analysis and included those of Yasumasu and colleagues (Yasumasu, Abe, Oginosawa, Takahara, & Nakashima, ; Yasumasu, Takahara, Abe, & Nakashima, ) with a measure of SV derived from admittance cardiography, and Vaschillo et al () using an indirect estimation of SV from continuous BP recording through the Modelflow method.…”

Sympathetic neural reactivity to mental stress differs in black and non-Hispanic white adults

“…A number of studies, like the present one, do not report any differences in baseline BRS between black and white subjects (28,32,34,35) while others have reported black subjects to have a lower cardiovagal BRS compared with white subjects (40,61). Previous findings have suggested that BRS could be affected by BMI (6,38,52); therefore, we accounted for that in the present study, and this did not alter our findings. Furthermore, individuals with a family history of hypertension have been reported to have a decrease in BRS (48), but in our sample we did not obtain the family history of most of the participants.…”