Analysis of interactions between heart rate and blood pressure in chronic hypertensive pregnancy

Normotensive pregnancies induce an adaption of the baroreflex sensitivity (BRS). Since hypertensive pregnancy disorders are a major cause of maternal mortality we investigated the beat-to-beat interval (BBI) and systolic blood pressure (SP) interactions in pregnant women with chronic hypertension in comparison to those in normotensive pregnant (PRE) and nonpregnant women (CON). Measures of joint symbolic dynamics (JSD) describing the coarse-grained behaviour of dynamical processes by means of symbols and the baroreflex sensitivity (BRS) according to the ´sequence method´ were used for assessing the interactions between BBI and SP. BRS was significantly reduced in all pregnancies compared with CON (p<0.00001) but there was no significant difference between CH and PRE. Contrary, the JSD measures revealed significant differences (p<0.00001) in the BBI and SP interactions between PRE and CH. In conclusion, JSD measures discover a different gestation related adaption of autonomic regulation in women with chronic hypertension and might be of relevance for risk stratification among hypertensive pregnancy disorders.