Transthoracic echocardiographic assessment of haemodynamics in severe pre-eclampsia and HIV in South Africa

The need for maternal critical care education, point-of-care ultrasound and critical care echocardiography in obstetric anesthesiologists training

Globally, the increase in medically complex obstetric patients is challenging the educational approach and clinical management of critically ill obstetric patients. This increase in medical complexity calls into question the educational paradigm in which future physicians are trained. Obstetric anesthesiologists, physician experts in the perio-perative planning and management of complex obstetric patients, represent an essential workforce in the strategies to address maternal mortality. Unfortunately, the development of peri-operative medicine and maternal critical care curricula has only received minor attention in most countries. Proposed guidelines and models highlight the existing need for tiered maternity care services in which critical care infrastructure plays a central role in the delivery of high-risk peripartum care. Therefore, the development of maternal critical care models designed to prepare obstetric anesthesiologists for the clinical challenges of a medically complex patient are warranted. Key critical care topics such as advanced ultrasonography, with the inclusion of quantitative echocardiographic assessments into obstetric anesthesiology educational curricula, will serve to better prepare physicians for the realities of an increasingly complex pregnant patient population, and further reinforce the critical care infrastructure detailed in the Levels of Maternal Care consensus. Despite an increasingly complex obstetric patient population, heterogeneity of maternal critical care practices exists across the globe, warranting standardization and further development of proposed curricula.

Cardiac magnetic resonance imaging in preeclampsia complicated by pulmonary edema shows myocardial edema with normal left ventricular systolic function

BACKGROUND

Preeclampsia complicates approximately 5% of all pregnancies. When pulmonary edema occurs, it accounts for 50% of preeclampsia-related mortality. Currently, there is no consensus on the degree to which left ventricular systolic dysfunction contributes to the development of pulmonary edema.

OBJECTIVE

This study aimed to use cardiac magnetic resonance imaging to detect subtle changes in left ventricular systolic function and evidence of acute left ventricular dysfunction (through tissue characterization) in women with preeclampsia complicated by pulmonary edema compared with both preeclamptic and normotensive controls.

STUDY DESIGN

Cases were postpartum women aged ≥18 years presenting with preeclampsia complicated by pulmonary edema. Of note, 2 control groups were recruited: women with preeclampsia without pulmonary edema and women with normotensive pregnancies. All women underwent echocardiography and 1.5T cardiac magnetic resonance imaging with native T1 and T2 mapping. Gadolinium contrast was administered to cases only. Because of small sample sizes, a nonparametric test (Kruskal-Wallis) with pairwise posthoc analysis using Bonferroni correction was used to compare the differences between the groups. Cardiac magnetic resonance images were interpreted by 2 independent reporters. The intraclass correlation coefficient was calculated to assess interobserver reliability.

RESULTS

Here, 20 women with preeclampsia complicated by pulmonary edema, 13 women with preeclampsia (5 with severe features and 8 without severe features), and 6 normotensive controls were recruited. There was no difference in the baseline characteristics between groups apart from the expected differences in blood pressure. Left atrial sizes were similar across all groups. Women with preeclampsia complicated by pulmonary edema had increased left ventricular mass (P=.01) but had normal systolic function compared with the normotensive controls. Furthermore, they had elevated native T1 values (P=.025) and a trend toward elevated T2 values (P=.07) in the absence of late gadolinium enhancement consistent with myocardial edema. Moreover, myocardial edema was present in all women with eclampsia or hemolysis, elevated liver enzymes, and low platelet count. Women with preeclampsia without severe features had similar findings to the normotensive controls. All cardiac magnetic resonance imaging measurements showed a very high level of interobserver correlation.

CONCLUSION

This study focused on cardiac magnetic resonance imaging in women with preeclampsia complicated by pulmonary edema, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count. We have demonstrated normal systolic function with myocardial edema in women with preeclampsia with these severe features. These findings implicate an acute myocardial process as part of this clinical syndrome. The pathogenesis of myocardial edema and its relationship to pulmonary edema require further elucidation. With normal left atrial sizes, any hemodynamic component must be acute.

Transthoracic echocardiographic assessment of the right ventricle before and after caesarean delivery: A preliminary investigation

Transthoracic echocardiographic evaluation of the right ventricle is more difficult than the left ventricle and has not been well characterised in the parturient during delivery. As a preliminary investigation, our goal was to use bedside transthoracic echocardiography to evaluate right ventricular myocardial function before and after caesarean delivery. Term parturients undergoing caesarean delivery under spinal anaesthesia were enrolled. Echocardiography was performed pre- and postoperatively. Assessment of myocardial function included longitudinal myocardial strain using 2D-speckle tracking for both ventricles, and fractional area change for the right ventricle. Troponin-T, creatine kinase-muscle/brain and brain natriuretic peptide were measured pre- and postoperatively. One hundred patients were enrolled; 98 completed the study. Adequate images from both timepoints (pre- and postoperatively) were obtained in 85 patients for left ventricle assessment, and 66 for the right ventricle. Right ventricular fractional area change (mean (standard deviation)) (24.9% (8.9%) to 24.9% (9.2%); P = 0.99) and strain (-19.7% (6.8%) to -18.1% (6.5%); P = 0.08) measurements suggested mild baseline dysfunction and did not change after delivery. Left ventricular strain values were normal and unchanged after delivery (-23.8% (7.4%) to -24.3% (6.7%); P = 0.51). One patient had elevated troponin-T and demonstrated worse biventricular function. Elevation of brain natriuretic peptide (n=7) was associated with mildly decreased left ventricular strain, but creatine kinase-muscle/brain (n=4) was not associated with consistent changes in cardiac function. Further investigations into peripartum right ventricular function are required to validate the findings in this preliminary study. Findings of baseline mild right ventricular dysfunction and functional changes associated with troponin-T and brain natriuretic peptide warrant rigorous investigation.

Cardiac Structure and Function in Morbidly Obese Parturients: An Echocardiographic Study

BACKGROUND

The increasing prevalence of obesity worldwide is a major threat to global health. Cardiac structural and functional changes are well documented for obesity as well as for pregnancy, but there is limited literature on morbidly obese parturients. We hypothesized that there are both cardiac structural and functional differences between morbidly obese pregnant women and pregnant women of normal body mass index (BMI).

METHODS

This prospective cross-sectional study was performed in 2 referral maternity units in Cape Town, South Africa, over a 3-month period. Forty morbidly obese pregnant women of BMI ≥40 kg·m (group O) were compared to 45 pregnant women of BMI ≤30 kg·m (group N). Cardiac structure and function were assessed by transthoracic echocardiography, according to the recommendations of the British Society of Echocardiography. The 2-sample t-test with unequal variances was used for the comparison of the mean values between the groups.

RESULTS

Acceptable echocardiographic images were obtained in all obese women. Statistical significance was defined as P < .0225 after applying the Benjamini-Hochberg correction for multiple testing. Mean (standard deviation) mean arterial pressure was higher in group O (91 [8.42] vs 84 [9.49] mm Hg, P < .001). There were no between-group differences in heart rate, stroke volume, or cardiac index (84 [12] vs 79 [13] beats·minute, P = .103; 64.4 [9.7] vs 59.5 [13.5] mL, P = .069; 2551 [474] vs 2729 [623] mL·minute·m, P = .156, for groups O and N, respectively). Stroke volume index was lower, and left ventricular mass was higher in group O (30.14 [4.51] vs 34.25 [7.00] mL·m, P = .003; 152 [24] vs 115 [29] g, P < .001). S' septal was lower in group O (8.43 [1.20] vs 9.25 [1.64] cm·second, P = .012). Considering diastolic function, isovolumetric relaxation time was significantly prolonged in group O (73 [15] vs 61 [15] milliseconds, P < .001). The septal tissue Doppler index E' septal was lower in group O (9.08 [1.69] vs 11.28 [3.18], P < .001). There were no between-group differences in E' average (10.7 [2.3] vs 12.0 [2.7], P = .018, O versus N) or E/E' average (7.85 [1.77] vs 7.27 [1.68], P = .137, O versus N). Right ventricular E'/A' was lower in group O (1.07 [0.47] vs 1.29 [0.32], P = .016).

CONCLUSIONS

Cardiac index did not differ between obese pregnant women and those with normal BMI. Their increased left ventricular mass and lower stroke volume index could indicate a limited adaptive reserve. Obese women had minor decreases in septal left ventricular tissue Doppler velocity, but the E/E' average values did not suggest clinically significant diastolic dysfunction.

Ischemic stroke and cerebral venous sinus thrombosis in pregnancy

Maternal ischemic stroke and cerebral venous sinus thrombosis (CVST) are dreaded complications of pregnancy and major contributors to maternal disability and mortality. This chapter summarizes the incidence and risk factors for maternal arterial ischemic stroke (AIS) and CVST and discusses the pathophysiology of maternal AIS and CVST. The diagnosis, treatment, and secondary preventive strategies for maternal stroke are also reviewed. Special populations at high risk of maternal stroke, including women with moyamoya disease, sickle cell disease, HIV, thrombophilia, and genetic cerebrovascular disorders, are highlighted.

Echocardiographic determination of resting haemodynamics and optimal positioning in term pregnant women

Optimal positioning for anaesthesia in pregnant women involves balancing the need for ideal tracheal intubation conditions (achieved by the head elevated ramped position), with the prevention of reduced cardiac output from aortocaval compression (achieved by left lateral pelvic tilt). No studies have examined the effect on cardiac output of left lateral pelvic tilt in the ramped position. We studied non-labouring, non-anaesthetised healthy term pregnant women who underwent baseline (left lateral decubitus) cardiac assessment using transthoracic echocardiography. We then compared cardiac output, maternal physiological variables, fetal heart rate and comfort scores in three positions: left lateral decubitus; ramped position with wedge; and ramped position alone. Thirty women completed the study. Mean (SD) age, gestation and body mass index were 33.5 (3.93) years, 38.5 (0.94) weeks and 29.0 (4.0) kg.m^-2 , respectively. Mean ejection fraction, left ventricular internal diameter and mitral valve E/e' were 55.2 (6.8) %, 4.70 (0.43) cm and 7.50 (1.82), respectively. There were no differences in cardiac output between the positions (p = 0.503). There were no differences in systolic (p = 0.955) or diastolic (p = 0.987) blood pressure, maternal heart rate (p = 0.133), oxygen saturation, respiratory rate (p = 0.964) or fetal heart rate (p = 0.361) between ramped with wedge and ramped alone positions. Left lateral decubitus was most comfortable (p = 0.001), however, there were no differences in comfort levels between ramped with wedge and ramped alone positions. The ramped position without left lateral tilt is safe and acceptable in non-labouring, non-anaesthetised, healthy term pregnant women. Left lateral pelvic tilt may be unnecessary in the head elevated ramped position in term pregnant women.

Maternal cardiac output response to colloid preload and vasopressor therapy during spinal anaesthesia for caesarean section in patients with severe pre-eclampsia: a randomised, controlled trial

We examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre-eclampsia. Twenty patients with pre-delivery spinal hypotension were randomly allocated to receive an initial dose of either 50 μg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300-ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min^-1 .m^-2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min^-1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049). Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min^-1 .m^-2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 [50-150] μg phenylephrine or 15 [7.5-37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at -12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at -9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. -1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesia-induced haemodynamic changes in severe pre-eclampsia, if left ventricular systolic function is preserved.