Assessment of venous hemodynamics and volume homeostasis during pregnancy: recommendations of the International Working Group on Maternal Hemodynamics

Agenesis of inferior vena cava in pregnancy: A case report and narrative review

Agenesis of inferior vena cava (AIVC) is an extremely rare congenital abnormality. In AIVC, venous flow from the lower extremities enter superior vena cava mainly through the azygous and hemiazygous system, forming anastomotic collateral vessels. A global increase in intra-abdominal pressure by the gravid uterus may further stress the collateral system, increase venous stasis and decrease venous return. We present the management of a 37-year old pregnant woman with AIVC who underwent caesarean section with norepinephrine infusion and general anaesthesia. She presented with shortness of breath when seated, episodes of dizziness while walking or sitting upright with subsequent tachycardia. Cardiac status was monitored using an arterial pulse contour CO monitor. We did not observe large fluctuations in CO, SV, MAP during induction and intubation as well as during delivery. We believe that administration of an infusion of norepinephrine from induction to anaesthesia through caesarean section contributed to this result. Sympathetic activation caused venoconstriction, which significantly increased venous return and maintained haemodynamic stability.

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Pre-Eclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

Effect of multidisciplinary team (MDT) centred on pregnant women with pulmonary hypertension on treatment and outcomes of pregnancy

BACKGROUND

The importance of multidisciplinary team (MDT) centred on pregnant women with pulmonary hypertension (PH) has been highlighted. However, rare studies have explored its effects on pregnancy outcomes. This study seeks to investigate whether and how the MDT has an effect on the treatment and outcomes of PH pregnant women.

METHODS

A pre- and post-intervention study was conducted based on an interrupted time series design to compare the treatment and outcomes of patients with PH before (pre-MDT) and after (post-MDT) implementation of the MDT. PH was defined as pulmonary artery systolic pressure (sPAP) ≥ 35 mmHg measured by echocardiography or right heart catheterization and sPAP at 35-60 mmHg and over 60 mmHg was defined as mild and severe PH, respectively. All results were analyzed by T-tests, Chi square tests or Fisher exact test and two-sided p value < 0.05 was set to be statistically significant.

RESULTS

149 pregnancies were found in 143 women with PH. Overall, 46 pregnancies were elective abortions, remaining 49 and 54 pregnancies completing delivery in the pre-MDT group and post-MDT group, respectively. Five (10.2%) mother and seven (8.6%) neonatal died in the former, while no maternal deaths but 1.9% neonatal death occurred in the latter. In subgroup analysis, maternal and fetal/neonatal complications were higher in patients with severe PH and World Health Organization functional class (WHO FC) III/IV and all maternal deaths occurred in class III/IV women. In pre-MDT and post-MDT groups, there were 8 and 22 pregnant women receiving the pulmonary-specific therapy and completing delivery, respectively. The percentage of heart failure and urgent cesarean of pre-MDT group was higher than the post-MDT group (30.6% vs. 12.9%, p = 0.02; 40.8% vs. 14.8%, p = 0.01, respectively).

CONCLUSION

Implementing the MDT decreased the rate of urgent caesarean section and heart failure in patients with PH and no maternal deaths occurred in the post-MDT group. Pregnant women with severe PH and WHO FC III/IV might have a poor prognosis, whereas the use of pulmonary-specific therapy might improve outcomes of pregnancy.

Characteristics of the Maternal Jugular Venous Pulse Waveform by Combined Doppler-Electrocardiogram Assessment

Standardized combined Doppler-electrocardiogram assessment was performed longitudinally at three different locations of internal jugular veins between 12 wk of gestation and 6 wk postnatally in 24 uncomplicated pregnancies. All images were classified as typical or non-typical based on the presence of the physiologic deflections A, X, H and C. Linear mixed models with random intercepts of typical images were used to investigate gestational changes in venous pulse transit time and venous impedance index. Unequivocal identification of venous pulse transit time and venous impedance index was possible in 2617 of 3798 (69%) and 2234 of 3798 (59%) images, respectively. The best identification rate (80%, 1018/1266) was at the right distal internal jugular vein. Venous pulse transit time increased with gestational age at all locations; venous impedance index decreased at the right sided internal jugular vein. Maternal jugular venous pulse waveform by combined Doppler-electrocardiogram allows unequivocal identification of A-deflection and calculation of venous pulse transit time and venous impedance index in around two-thirds of assessments, with the highest success rate at the right distal internal jugular vein. Gestational evolutions of venous pulse transit time and venous impedance index are similar to those reported at the level of renal interlobar and hepatic veins.

Hemodynamic pathways of gestational hypertension and preeclampsia

Gestational hypertension and preeclampsia are the 2 main types of hypertensive disorders in pregnancy. Noninvasive maternal cardiovascular function assessment, which helps obtain information from all the components of circulation, has shown that venous hemodynamic dysfunction is a feature of preeclampsia but not of gestational hypertension. Venous congestion is a known cause of organ dysfunction, but its potential role in the pathophysiology of preeclampsia is currently poorly investigated. Body water volume expansion occurs in both gestational hypertension and preeclampsia, and this is associated with the common feature of new-onset hypertension after 20 weeks of gestation. Blood pressure, by definition, is the product of intravascular volume load and vascular resistance (Ohm's law). Fundamentally, hypertension may present as a spectrum of cardiovascular states varying between 2 extremes: one with a predominance of raised cardiac output and the other with a predominance of increased total peripheral resistance. In clinical practice, however, this bipolar nature of hypertension is rarely considered, despite the important implications for screening, prevention, management, and monitoring of disease. This review summarizes the evidence of type-specific hemodynamic profiles in the latent and clinical stages of hypertensive disorders in pregnancy. Gestational volume expansion superimposed on an early gestational closed circulatory circuit in a pressure- or volume-overloaded condition predisposes a patient to the gradual deterioration of overall circulatory function, finally presenting as gestational hypertension or preeclampsia-the latter when venous dysfunction is involved. The eventual phenotype of hypertensive disorder is already predictable from early gestation onward, on the condition of including information from all the major components of circulation into the maternal cardiovascular assessment: the heart, central and peripheral arteries, conductive and capacitance veins, and body water content. The relevance of this approach, outlined in this review, openly invites for more in-depth research into the fundamental hemodynamics of gestational hypertensive disorders, not only from the perspective of the physiologist or the scientist, but also in assistance of clinicians toward understanding and managing effectively these severe complications of pregnancy.

Heart rate variability in Dorper sheep in the fetal and neonatal periods until 120 days of age: Use of the technique in the field

The evaluation of the autonomic cardiac functions may be performed through the analysis of the heart rate variability. Heart rate variability is defined as the fluctuations in the heart rhythm or rate, and represents a useful tool in the evaluation of the autonomic nervous system through the sympathetic and parasympathetic components, as well as its balance and its reflexes on the cardiorespiratory control system. Fetal electrocardiography provides important information regarding the well-being of the fetus since, in human fetuses, there are changes in the behavior of the fetal heart rate during the second and third trimesters of pregnancy due to an increase in parasympathetic activity. Therefore, considering the importance of evaluating fetal viability, this study aims at evaluating the behavior of fetal heart rate and heart rate variability in Dorper sheep, as well as the activity of the autonomic nervous system during fetal life and in newborn lambs. The species is often used in experimental studies and autonomic nervous system activity is a prognostic index, therefore, the diagnosis of modifications in the sympathovagal balance may represent an early index for fetal viability and well-being in lambs. The analyses were performed in 10 Dorper sheep during pregnancy and in 10 lambs after birth until 120 days of age. There was a decrease in the fetal heart rate and heart rate variability indexes during the fifth month of pregnancy, but without statistical significance for the period evaluated. The heart rate of the lambs decreased gradually until they were 21 days old. The indexes SDNN (standard deviation of RR intervals) and RMSSD (square root of the mean of successive differences between adjacent RR intervals) diverged according to age, being high at day 60. Fetal viability is relevant in sheep fetuses to avoid losses during pregnancy and risks to the health of the mother. In the species, there seems to be a predominance of parasympathetic activity starting from the 21st day of age. Heart rate variability may be employed as a tool in the evaluation of the fetus and development of lambs, since changes in its behavior may represent an adverse effect to fetal and neonatal health.

Venous blood flow in maternal kidneys in third trimester of pregnancy

Objectives: Maternal intra-abdominal pressure and hemodynamics change during pregnancy. The left renal vein may be compressed between the uterus and the spine and aorta, causing congestion and impaired venous return from the left kidney during late pregnancy. The aim of this study was to compare venous and arterial blood flow between the right and left kidney in the third trimester in women without known pregnancy complications.Methods: We conducted a prospective cohort study in 50 women with uncomplicated third-trimester pregnancies at Trondheim University Hospital, Norway, from January to April 2018. The arterial and venous blood flow were examined with pulsed wave Doppler in the hilum of the kidneys and the cross section of the area (CSA) of the vessels was measured from 3D acquisitions. Two diameters of the main vein and artery were measured after rotating the image of the vessels in the C-plane to be as circular as possible. CSA was calculated as π×(mean diameter/2)². Blood flow volume (ml/minute) in the vessels were calculated as 0.5 × TAmax (cm/s)×CSA (cm²)×60. The main outcome was venous and arterial blood flow volumes, and secondary outcomes were maximum velocity (Vmax), minimum velocity (Vmin), pulsatile index (PI), time-averaged maximum flow (TAmax) and renal interolobar vein impedance index (RIVI). We also examined possible associations between blood flow and maternal age, BMI and blood pressure.Results: We observed differences in venous flow parameters between the two kidneys. The mean total flow volume in the renal veins was 274 ml/min in the left vein versus 358 ml/min in the right vein (p=.10). Vmax, TAmax, PI, and RIVI were all significantly lower in the left renal vein. No differences in arterial blood flow between the two kidneys were found. BMI was negatively correlated to flow in the left renal vein (r= -0.28; p<.05), but not associated to flow in the right renal vein.Conclusion: We found that venous flow pattern differs between left and right renal veins in uncomplicated late pregnancies, but the total flow was not significantly different. New studies should be done in women with preeclampsia.