Objective: The baroreflex sensitivity and the distensibility of the carotid artery were measured during normotensive pregnancy to test the hypothesis that changes in baroreflex sensitivity are related to carotid artery stiffening.
Design: Data were obtained from pregnant subjects during each trimester (T1, T2, T3; n = 23) and postpartum (n = 11). End-diastolic diameter and pulsatile distension of the carotid artery were measured with an ultrasound wall-tracking system, and the distensibility coefficient was calculated. Spontaneous fluctuations in cardiac interval and systolic pressure were used to determine baroreflex sensitivity.
Results: Both distensibility coefficient and baroreflex sensitivity were reduced from T1 to T3 (5.1 +/- 1.6 vs. 3.7 +/- 0.9 10(-3)/mmHg and 10.1 +/- 2.9 vs. 5.7 +/- 1.8 ms/mmHg, respectively). Baroreflex sensitivity and carotid distensibility coefficient were linearly related in each subject (r = 0.62 +/- 0.12). Augmentation index and return time changes indicated a global increase in arterial distensibility.
Conclusions: Stiffening of the carotid artery significantly contributes to the impairment of baroreflex sensitivity during pregnancy, and represents a region specific change as global arterial distensibility was found to increase during pregnancy.