Maternal Functional Hemodynamics in the Second Half of Pregnancy: A Longitudinal Study

Abstract

ObjectiveCardiovascular response to passive leg raising (PLR) is useful in assessing preload reserve, but it has not been studied longitudinally during pregnancy. We aimed to investigate gestational age associated serial changes in maternal functional hemodynamics and establish longitudinal reference ranges for the second half of pregnancy.Materials and MethodsThis was a prospective longitudinal study on 98 healthy pregnant women who were examined 3–5 times during 20–40 weeks of gestation (a total of 441 observations). Maternal cardiac function and systemic hemodynamics were assessed at baseline and 90 seconds after PLR using impedance cardiography (ICG). The main outcome measures were gestational age specific changes in ICG-derived variables of maternal cardiovascular function and functional hemodynamic response to PLR.ResultsHemodynamic response to PLR varied during pregnancy. PLR led to an insignificant increase in stroke volume during 20+0 to 31+6 weeks, but later in gestation the stroke volume was slightly lower at PLR compared to baseline. PLR caused no significant change in cardiac output between 20+0 and 23+6 weeks and a significant decrease after 24+0 weeks. A decrease in heart rate, mean arterial pressure, and cardiac contractility was observed during PLR throughout the second half of pregnancy. Systemic vascular resistance was reduced by PLR up to 32+0 weeks, but increased slightly thereafter.ConclusionHealthy pregnant women appear to have limited preload reserve and reduced cardiac contractility, especially in the third trimester, which makes them vulnerable to fluid overload and cardiac failure.

Maternal functional hemodynamics in uncomplicated twin pregnancies: A longitudinal study using impedance cardiography

“…The response to PLR may be affected by the blood volume mobilized with other factors (eg total circulating blood volume, baseline preload and cardiac contractility). Cardiovascular response to PLR has been studied in the second half of singleton pregnancies by Vårtun et al; PLR led to a nonsignificant increase in SV from 20 +0 to 31 +6 weeks compared with baseline, whereas CO significantly decreases after 24 +0 weeks. Similarly, Guy et al recently demonstrated that PLR results in an increase in preload with a consequent increase in cardiac index and SI and a decrease in SVRI in 2764 normotensive women with singleton pregnancy at 35‐37 weeks’ gestation .…”

“…Of note, VI and ACI were negatively affected by PLR in the first and second trimesters of pregnancy, respectively, whereas LVET and PEP were increased in the same timeframes. Although a reduction in myocardial contractility might represent one of the underlying mechanisms leading to myocardial inability to increase SV in response to PLR, compromised venous return due to caval compression and fluid shifts, including positioning of breast tissue, with the postural change could be another reason for the lack of positive response to PLR, as well as the small sample size. Indeed, Guy et al demonstrated a significant increase of only 3% in cardiac index and SI with PLR starting from the left lateral decubitus in 2764 singleton pregnancies near term In contrast, Liang et al reported no difference starting from a semi‐recumbent position in 53 singleton pregnancies in the second and third trimester …”

Maternal cardiac function, uterine artery hemodynamics and natriuretic peptides at 22‐24 weeks of gestation and subsequent development of hypertensive disorders of pregnancy

“…Maternal cardiac function and systemic hemodynamics were investigated using impedance cardiography (ICG; Philips Medical Systems, Androver, MA, USA) as described previously. 6,7,23 ICG is a validated noninvasive technique 24 that allows continuous recording and onscreen display of measured parameters. A single investigator (Å.V.)…”

“…1,2 Passive leg raising (PLR), a maneuver of lifting the legs from the horizontal plane to 45° using a pivotable bed, provides a rapid reversible auto-fluid challenge by increasing venous return to the heart. 6,7 Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are the most important members of the natriuretic peptide family that are involved in maintaining volume homeostasis and endothelial function. 4,5 Using this method, we previously showed that pregnant women have a limited preload reserve.…”

“…4,5 Using this method, we previously showed that pregnant women have a limited preload reserve. 6,7 Atrial natriuretic peptide (ANP), brain natriuretic peptide(BNP) and C-type natriuretic peptide (CNP) are the most important members of the natriuretic peptide family that are involved in maintaining volume homeostasis and endothelial function. ANP and BNP are of myocardial origin 8 and are known to be produced in response to myocardial wall stress or pressure overload.…”