ABC | Volume 114, Nº4, April 2020

Original Article Linhares et al. Hydrotherapy reduces arterial stiffness in pregnant women Arq Bras Cardiol. 2020; 114(4):647-654 Figure 2 – Variations in heart rate (A) and brachial (peripheral) systolic blood pressure (B) before and after a hydrotherapy session in the control (CG) and hypertensive (HG) groups. Frequência cardíaca (bpm) Sistolic Blood Pressure (mm Hg) 120 110 100 90 80 70 60 160 140 120 100 80 60 Before After Before After Control Hypertensive Control Hypertensive p < 0.001 p < 0.001 p = 0.404 p = 0.050 A B Finkelstein et al. 41 found a significant reduction in HR and BP among pregnant women immersed up to the level of the xiphoid process, as done in our study. The authors suggest that this decrease may be related to decreased plasma renin activity and increased atrial natriuretic peptide concentration in response to blood volume expansion in water. Elvan‑Taşpınar et al. 42 compared the effect on central and peripheral hemodynamics of simple immersion in water at 35°C for 3 hours in a small sample divided into 3 groups: normal‑risk pregnant women, pregnant women with preeclampsia, and nonpregnant women. The authors observed a transient reduction in HR, DBP, and total peripheral resistance. 42 Still, there is evidence that exercise produces a significant additional cardiovascular impact during pregnancy and in other clinical conditions. 36,43-45 In a study by Ward et al. 25 evaluating the impact of aquatic physical therapy in normotensive pregnant women, no significant changes in post-immersion BP compared with pre-immersion BP were observed; however, a significant reduction in MBP in the post-exercise phase was noted. Coelho et al. 45 demonstrated a significant reduction in SBP, DBP, and MBP among pregnant women without hypertension 45 and 60 minutes after an aquatic exercise session. We conclude that there is sufficient evidence showing that aquatic physical therapy promotes an impact on BP components through an interaction of the effects of its three fundamental elements: temperature, immersion, and exercise. Although still an area with limited research, these studies demonstrated the effects of hydrotherapy on BP in normal individuals, pregnant or not, opening up to possibilities of intervention in hypertensive pregnant women. However, there is no previous evidence in the literature about the impact of hydrotherapy on AS in pregnant women with CH, a parameter evaluated in our study. Measurements of AS, such as the ones expressed by AIx@75, as well as central SBP (cSBP), have been shown to be more sensitive independent predictors of future cardiovascular events compared with conventional bBP in various clinical conditions 46-49 and in pregnancy. 50,51 The AIx@75 has been shown to be independent of bBP during pregnancy, indicating that the AIx@75 measurement may reflect arterial compliance during pregnancy. 50 A close inverse association between the newborn's birth weight and AS of normotensive pregnant women has also been demonstrated, indicating that abnormal pressure-wave reflection may affect fetal growth even in the absence of hypertension. 51 Additionally, increased AIx@75 and cSBP have been observed in women with newly diagnosed preeclampsia. 52 Khalil et al. 9 demonstrated a change in pressure-wave reflection after the first trimester of pregnancy in women developing preeclampsia. Yinon et al. 10 demonstrated increased AIx@75 percentages up to 6 to 24 months after delivery in pregnant women with a history of intrauterine growth restriction and/or early-onset preeclampsia. Tomimatsu et al. 53 showed that abnormal pressure-wave reflection during the 26 to 32 gestational weeks correlated more strongly with birth weight than conventional bBP, to the extent that AIx@75 was the only hemodynamic parameter significantly elevated in pregnant women who developed fetal growth restriction. Such evidence corroborates our findings of decreased AIx@75 without significant bSBP reduction with hydrotherapy. We demonstrated in our study that a single hydrotherapy session was able to decrease AIx@75 acutely by 22.2% and 21.3% in pregnant women with CH and controls, respectively. The intervention proved to be safe and may represent a potential non-pharmacological therapeutic strategy for pregnant women with CH in preventing maternal and fetal complications. 651