Effects of pregnancy on electrocardiographic, vasovagal tonus index, and echocardiographic variables in horses

Background and Aim

Pregnancy affects maternal hemodynamics. The changes in autonomic nervous system activity for hemodynamics adaptation in pregnant horses are still unclear. Thus, this study aimed to examine the effect of pregnancy on electrocardiographic, vasovagal tonus index, and echocardiographic variables in horses.

Materials and Methods

A total of 23 Thai native crossbred mares without any cardiac abnormalities were included in this study. The animals were assigned into two groups, a non-pregnant mare group (n =12) and a pregnant mare group (n = 11). Electrocardiogram recordings (paper speed = 25 mm/s and calibration = 10 mm/mV) were performed to obtain six limb leads (leads I, II, III, aVR, aVL, and aVF). The vasovagal tonus index (VVTI) was calculated to assess variability in heart rate over short periods using just 20 consecutive beats. Cardiac structure and function were evaluated by echocardiography.

Results

Heart rate, P wave duration, PR interval, QRS duration, QT interval, and T wave duration were significantly different between non-pregnant and pregnant horses (p < 0.05). Pregnant horses had significantly lower VVTI than non-pregnant (p < 0.05). There were no significant differences in cardiac structures including % interventricular septum (IVS), % left ventricular posterior wall (LVPW), IVS in diastole, left ventricular internal diameter at end-diastole, LVPW thickness at end-diastole, IVS in systole, left ventricular internal diameter at end-systole, LVPW thickness at end-systole, and left atrium/aortic roots ratio between the two groups. However, the pregnant horses had a significantly higher cardiac output and % ejection fraction than non-pregnant horses (p < 0.05).

Conclusion

This study provided the first evidence that hemodynamic adaptations during pregnancy modified cardiac conduction, vasovagal tonus index, and echocardiographic variables in horses.

Evaluation of Cardiac Function in Women With a History of Preeclampsia: A Systematic Review and Meta-Analysis

Background

Women with a history of preeclampsia are at increased risk of cardiovascular morbidity and mortality. However, the underlying mechanisms of disease association, and the ideal method of monitoring this high‐risk group, remains unclear. This review aims to determine whether women with a history of preeclampsia show clinical or subclinical cardiac changes when evaluated with an echocardiogram.

Methods and Results

A systematic search of MEDLINE, EMBASE, and CINAHL databases was performed to identify studies that examined cardiac function in women with a history of preeclampsia, in comparison with those with normotensive pregnancies. In the 27 included studies, we found no significant differences between preeclampsia and nonpreeclampsia women with regard to left ventricular ejection fraction, isovolumetric relaxation time, or deceleration time. Women with a history of preeclampsia demonstrated a higher left ventricular mass index and relative wall thickness with a mean difference of 4.25 g/m² (95% CI, 2.08, 6.42) and 0.03 (95% CI, 0.01, 0.05), respectively. In comparison with the nonpreeclampsia population, they also demonstrated a lower E/A and a higher E/e′ ratio with a mean difference of −0.08 (95% CI, −0.15, −0.01) and 0.84 (95% CI, 0.41, 1.27), respectively.

Conclusions

In comparison with women who had a normotensive pregnancy, women with a history of preeclampsia demonstrated a trend toward altered cardiac structure and function. Further studies with larger sample sizes and consistent echocardiogram reporting with the use of sensitive preclinical markers are required to assess the role of echocardiography in monitoring this high‐risk population group.

Preeclampsia: a gestational cardiorenal syndrome

It is generally accepted today that there are two different types of preeclampsia: an early-onset or placental type and a late-onset or maternal type. In the latent phase, the first one presents with a low output/high resistance circulation eventually leading in the late second or early third trimester to an intense and acutely aggravating systemic disorder with an important impact on maternal and neonatal mortality and morbidity; the other type presents initially as a high volume/low resistance circulation, gradually evolving to a state of circulatory decompensation usually in the later stages of pregnancy, with a less severe impact on maternal and neonatal outcome. For both processes, numerous dysfunctions of the heart, kidneys, arteries, veins and interconnecting systems are reported, most of them presenting earlier and more severely in early- than in late-onset preeclampsia; however, some very specific dysfunctions exist for either type. Experimental, clinical and epidemiological observations before, during and after pregnancy are consistent with gestation-induced worsening of subclinical pre-existing chronic cardiovascular dysfunction in early-onset preeclampsia, and thus sharing the pathophysiology of cardiorenal syndrome type II, and with acute volume overload decompensation of the maternal circulation in late-onset preeclampsia, thus sharing the pathophysiology of cardiorenal syndrome type 1. Cardiorenal syndrome type V is consistent with the process of preeclampsia superimposed upon clinical cardiovascular and/or renal disease, alone or as part of a systemic disorder. This review focuses on the specific differences in haemodynamic dysfunctions between the two types of preeclampsia, with special emphasis on the interorgan interactions between heart and kidneys, introducing the theoretical concept that the pathophysiological processes of preeclampsia can be regarded as the gestational manifestations of cardiorenal syndromes.

Maternal Venous Hemodynamic Dysfunction in Proteinuric Gestational Hypertension: Evidence and Implications

This review summarizes current knowledge from experimental and clinical studies on renal function and venous hemodynamics in normal pregnancy, in gestational hypertension (GH) and in two types of preeclampsia: placental or early-onset preeclampsia (EPE) and maternal or late-onset (LPE) preeclampsia, presenting at <34 weeks and ≥34 weeks respectively. In addition, data from maternal venous Doppler studies are summarized, showing evidence for (1) the maternal circulation functioning closer to the upper limits of capacitance than in non-pregnant conditions, with intrinsic risks for volume overload, (2) abnormal venous Doppler measurements obtainable in preeclampsia, more pronounced in EPE than LPE, however not observed in GH, and (3) abnormal venous hemodynamic function installing gradually from first to third trimester within unique pathways of general circulatory deterioration in GH, EPE and LPE. These associations have important clinical implications in terms of screening, diagnosis, prevention and management of gestational hypertensive diseases. They invite for further hypothesis-driven research on the role of retrograde venous congestion in the etiology of preeclampsia-related organ dysfunctions and their absence in GH, and also challenge the generally accepted view of abnormal placentation as the primary cause of preeclampsia. The striking similarity between abnormal maternal venous Doppler flow patterns and those observed at the ductus venosus and other abdominal veins of the intra-uterine growth restricted fetus, also invites to explore the role of venous congestion in the intra-uterine programming of some adult diseases.

Is preeclampsia an independent predictor of diastolic dysfunction? A retrospective cohort study

OBJECTIVE

To determine if preeclampsia is an independent predictor of diastolic dysfunction and what factors among patients with preeclampsia are associated with diastolic dysfunction.

METHODS

This is a retrospective cohort study of patients who delivered between 2008 and 2013 at a single institution who had a maternal echocardiogram during their pregnancy or within 5months of delivery. Patients with structural heart disease, ejection fraction less than 45%, pulmonary embolus, or age over 45years were excluded. Medical records were reviewed for medical and obstetric complications and echocardiogram findings. Demographic characteristics and rate of diastolic dysfunction were compared between patients with preeclampsia and without preeclampsia. Multivariate logistic regression was performed controlling for age, ethnicity, gestational age at delivery, diabetes, preeclampsia, intrauterine growth restriction (IUGR), antihypertensive use and magnesium sulfate administration.

RESULTS

Sixty-six patients were identified, of which 39 (59%) had preeclampsia. Past history of preeclampsia, IUGR in the current pregnancy, antihypertensive use and magnesium sulfate use were higher in the preeclampsia group. Fifteen patients (39%) in the preeclampsia group were African-American compared to 2 (3%) in the control group (p<0.01). Seventeen (44%) of the patients with preeclampsia were found to have diastolic dysfunction compared to 3 (11%) controls (OR=6.18, 95% CI 1.59,24.02; p=0.006). Logistic regression analysis did not reveal other independent predictors of diastolic dysfunction. In the patients with preeclampsia, history of preeclampsia with severe features and IUGR were not associated with diastolic dysfunction.

CONCLUSIONS

Our study supports previous findings that preeclampsia is associated with diastolic dysfunction.

Post-partum evaluation of maternal cardiac function after severe preeclampsia

OBJECTIVE

To evaluate the post-partum maternal cardiac function in patients with history of severe preeclampsia.

METHODS

A series of women with previous singleton pregnancy complicated by severe preeclampsia underwent transthoracic echocardiography at 6-12 months from delivery. A group of women with previous uncomplicated pregnancy was selected as controls.

RESULTS

Sixteen women with history of severe preeclampsia were enrolled in the study group whereas 18 patients were selected as controls. In the study group systolic (p=0.002) and diastolic blood pressure (p=0.044) were significantly higher. Significant differences were observed in systolic left ventricular (LV) parameters, such as cardiac output (p=0.034), LV mass indexed to BSA (p=0.024) and longitudinal contraction, expressed by tissue Doppler (TD) S1 wave, which resulted relatively impaired in former preeclamptic women (p=0.049). As regards as diastolic parameters, pulsed Doppler A-wave velocity was increased (p=0.036). TD E-wave velocity was significantly lower in study group (p<0.001) and E/E1 ratio (E=peak early diastole transmitral wave velocity/E1=peak early diastolic velocity at mitral valve annulus at TD) was higher respect to controls (p<0.001).

CONCLUSIONS

LV contractility and diastolic function, although within normal reference ranges, show slight but significant impairment among women who experienced a severe preeclampsia. TD seems to be a sensible tool to identify these precocious signs of potential LV dysfunction.

Early pregnancy circulatory adaptation and recurrent hypertensive disease: an explorative study

INTRODUCTION

Hypertensive pregnancy disorders are assumed to be preceded by defective spiral artery remodeling. Whether this localized aberration at the implantation site affects the initial maternal systemic cardiovascular and renal adaptation to pregnancy is unclear. We explored in a high-risk population, whether the initial systemic maternal adaptation to pregnancy differs between women who do and do not develop a recurrent hypertensive disorder later on in pregnancy.

METHODS

We enrolled 61 normotensive women with a previous hypertensive disorder of pregnancy and subdivided them into 2 subgroups, based on whether or not their next pregnancy remained uneventful (n = 33) or became complicated by a recurrent hypertensive disorder (n = 28). We measured before pregnancy and again at 18 ± 2 weeks of gestation cardiac output, blood pressure, plasma volume, creatinine clearance, and calculated total peripheral vascular resistance from cardiac output and blood pressure.

RESULT

Both subgroups responded to pregnancy with an increase in cardiac output, plasma volume, heart rate, and creatinine clearance, and a decrease in blood pressure and total peripheral vascular resistance. Women who developed a recurrent hypertensive disorder differed from their counterparts with an uneventful next pregnancy by smaller pregnancy-induced increases in creatinine clearance (19% vs. 31%, P = .035) and cardiac output (10% vs. 20%, P = .035), respectively.

CONCLUSION

The initial systemic cardiovascular and renal adaptations to pregnancy in women who develop a recurrent gestational hypertensive disorder differ from those in their counterparts with an uneventful next pregnancy by smaller rises in creatinine clearance and cardiac output.

Role of dysfunctional maternal venous hemodynamics in the pathophysiology of pre-eclampsia: a review

The venous compartment has an important function in regulation and control of cardiac output. Abnormalities of cardiac output have been found in early gestational stages of both early- and late-onset pre-eclampsia. The venous compartment also maintains the balance between circulating and non-circulating blood volumes and regulates the amount of reserve blood stored in the splanchnic venous bed. It is well known that adaptive regulation of maternal blood volume is disturbed in pre-eclampsia. Abnormal venous hemodynamics and venous congestion are responsible for secondary dysfunction of several organs, such as the kidneys in cardiorenal syndrome and the liver in cardiac cirrhosis. Renal and liver dysfunctions are among the most relevant clinical features of pre-eclampsia. Doppler sonography studies have shown that the maternal venous compartment is subject to gestational adaptation, and that blood flow characteristics at the level of renal interlobar and hepatic veins are different in pre-eclampsia compared with uncomplicated pregnancy. In comparison to late-onset pre-eclampsia, in early-onset pre-eclampsia venous Doppler flow abnormalities are more prominent and present up to weeks before clinical symptoms. This paper reviews the growing evidence that dysfunction of maternal venous hemodynamics is part of the pathophysiology of pre-eclampsia and may perhaps be more important than is currently considered. Doppler sonography is a safe and easily performed method with which to study maternal venous hemodynamics. Therefore, exploring the role of maternal venous hemodynamics using Doppler sonography is an exciting new research topic for those who are interested in cardiovascular background mechanisms, as well as prediction and clinical work-up of pre-eclampsia.

Blood pressure and heart rate variability complexity analysis in pregnant women with hypertension

BACKGROUND

In this work, we perform a comparative analysis of blood pressure and heart rate variability complexity during pregnancy between normal, hypertensive, and preeclamptic women.

METHODS AND RESULTS

A total of 563 short electrocardiographic (10 min) records were obtained from 217 pregnant women (135 normal, 55 hypertensive, and 27 preeclamptic) during several gestational ages in sitting position. We used a mixed unbalanced model for the longitudinal statistical analysis and besides the conventional spectral analysis, we applied Lempel-Ziv complexity, sample entropy, approximated entropy, and detrended fluctuation analysis in the complexity measurement.

CONCLUSIONS

The obtained results revealed significant differences between pathological and normal states with important considerations related to pregnancy adaptability and evolution as well as the relationship of complexity and blood pressure with factors such as maternal age, familial history of diabetes or hypertension, and parity.