Evaluation of fetal and uterine hemodynamics during maternal cardiopulmonary bypass

Fetal Doppler monitoring during maternal open-heart surgery: Case report and key aspects of a multidisciplinary challenge

CASE REPORT

Herein we present the case of a 33-year nulliparous woman at 21 weeks of gestation with mitral valve vegetation resulting from infective endocarditis. Due to the mother's critical condition caused by consecutive thromboembolic events, surgery with cardiopulmonary bypass was indicated. During surgery the fetus was monitored by a specialized obstetrician who repetitively measured the Doppler indices of the umbilical artery, Ductus venosus and uterine artery. Right after CO₂ was insufflated into the operating area, the Doppler monitoring showed an increased Pulsatility Index of the Umbilical artery right before fetal distress with bradycardia occurred. A subsequent maternal arterial blood gas analysis showed an acidosis with hypercapnia. Consequently, the CO₂ insufflation was stopped and the gas flow on the Heart Lung Machine increased. After regaining homeostasis of acidosis, the Doppler Indices and fetal heart rate recovered. The remaining surgery and postoperative course were uneventful. At the 37 weeks of gestation a healthy boy was delivered by Cesarean section and at the age of two years, the neurodevelopment was assessed, which indicated normal development in mental cognition, language and motoric. This report presents a periodic Doppler examination of the maternal and fetal circulation during surgery on CPB while also discussing the possible impact of fetal monitoring in managing open cardiac surgery in pregnancy.

The placenta and preeclampsia: villain or victim?

Preeclampsia is a disease whose characterization has not changed in the 150 years since the cluster of signs associated with the disorder were first described. Although our understanding of the pathophysiology of preeclampsia has advanced considerably since then, there is still little consensus regarding the true etiology of preeclampsia. As a consequence, preeclampsia has earned the moniker "disease of theories," predominantly because the underlying biological mechanisms linking clinical epidemiologic findings to observed organ dysfunction in preeclampsia are far from clear. Despite the lack of cohesive evidence, expert consensus favors the hypothesis that preeclampsia is a primary placental disorder. However, there is now emerging evidence that suboptimal maternal cardiovascular performance resulting in uteroplacental hypoperfusion is more likely to be the cause of secondary placental dysfunction in preeclampsia. Preeclampsia and cardiovascular disease share the same risk factors, preexisting cardiovascular disease is the strongest risk factor (chronic hypertension, congenital heart disease) for developing preeclampsia, and there are now abundant data from maternal echocardiography and angiogenic marker studies that cardiovascular dysfunction precedes the development of preeclampsia by several weeks or months. Importantly, cardiovascular signs and symptoms (hypertension, cerebral edema, cardiac dysfunction) predominate in preeclampsia at clinical presentation and persist into the postnatal period with a 30% risk of chronic hypertension in the decade after birth. Placental malperfusion caused by suboptimal maternal cardiovascular performance may lead to preeclampsia, thereby explaining the preponderance of cardiovascular drugs (aspirin, calcium, statins, metformin, and antihypertensives) in preeclampsia prevention strategies. Despite the seriousness of the maternal and fetal consequences, we are still developing sensitive screening, reliable diagnostic, effective therapeutic, or improvement strategies for postpartum maternal cardiovascular legacy in preeclampsia. The latter will only become clear with an acceptance and understanding of the cardiovascular etiology of preeclampsia.

[Valve sparing aortic root replacement (David Procedure) in 36 year - old woman with the Marfan syndrome at the 27th week of pregnancy]

The article presents a clinical case of valve sparing aortic root replacement (David Procedure) in 36 year - old woman with the Marfan syndrome at the 27th week of gestation followed by successful prolongation of pregnancy. Indications for reconstructive intervention with cardiopulmonary bypass were: severe aortic valve insufficiency, Sinus of Valsalva Aneurysm (66 mm) and the ascending aorta dilatation (53 mm) with a rapid increase of aortic root dimension (12 mm during 9 weeks). The patient underwent a valve sparing aortic root replacement according to David procedure using Gelweave Valsalva graft (Vascutec) No 28 The time of cardiopulmonary bypass was 137 minutes; the time of aortic cross-clamping was 107 minutes. The patient was discharged from the hospital in a satisfactory condition in 21 days after the operation. Pregnancy was prolonged and ended with a planned cesarean section at 38 weeks of gestation, the birth of a boy with an Apgar score of 7/8.

Indications for Cardiopulmonary Bypass During Pregnancy and Impact on Fetal Outcomes

Background: Cardiac operations in pregnant patients are a challenge for physicians in multidisciplinary teams due to the complexity of the condition which affects both mother and baby. Management strategies vary on a case-by-case basis. Feto-neonatal and maternal outcomes after cardiopulmonary bypass (CPB) in pregnancy, especially long-term follow-up results, have not been sufficiently described. Methods: This review was based on a complete literature retrieval of articles published between 1991 and April 30, 2013. Results: Indications for CPB during pregnancy were cardiac surgery in 150 (96.8 %) patients, most of which consisted of valve replacements for mitral and/or aortic valve disorders, resuscitation due to amniotic fluid embolism, autotransfusion, and circulatory support during cesarean section to improve patient survival in 5 (3.2 %) patients. During CPB, fetuses showed either a brief heart rate drop with natural recovery after surgery or, in most cases, fetal heart rate remained normal throughout the whole course of CPB. Overall feto-neonatal mortality was 18.6 %. In comparison with pregnant patients whose baby survived, feto-neonatal death occurred after a significantly shorter gestational period at the time of onset of cardiac symptoms, cardiac surgery/resuscitation under CPB in the whole patient setting, or cardiac surgery/resuscitation with CPB prior to delivery. Conclusions: The most common surgical indications for CPB during pregnancy were cardiac surgery, followed by resuscitation for cardiopulmonary collapse. CPB was used most frequently in maternal cardiac surgery/resuscitation in the second trimester. Improved CPB conditions including high flow, high pressure and normothermia or mild hypothermia during pregnancy have benefited maternal and feto-neonatal outcomes. A shorter gestational period and the use of CPB during pregnancy were closely associated with feto-neonatal mortality. It is therefore important to attempt delivery ahead of surgery/CPB or to defer surgery till late pregnancy.

Prevalence of maternal cardiac defects in women with high-resistance uterine artery Doppler indices

OBJECTIVES

To compare the prevalence of previously undiagnosed cardiac structural abnormalities in pregnant women with normal- and high-resistance midtrimester uterine artery Doppler indices.

METHODS

Maternal transthoracic echocardiography was undertaken in asymptomatic pregnant women after uterine artery Doppler screening for pre-eclampsia at 21-23 weeks' gestation. Women with a mean uterine artery pulsatility index above the 90(th) centile (1.25) for the local population (multiethnic, socially diverse and migrant) were considered to have high-resistance uteroplacental blood flow indices. The prevalence of newly diagnosed cardiac structural defects in these women was recorded.

RESULTS

A total of 491 women underwent echocardiography, of whom 205 had high-resistance uterine artery blood flow indices. There were nine previously undiagnosed, functionally significant cardiac defects in the high-resistance uterine artery blood flow group and only one, functionally insignificant cardiac defect in the normal-resistance group (P = 0.005; relative risk = 12.6, 95% confidence interval, 1.60-98.34). Multiple regression analysis demonstrated that both uterine artery Doppler indices (P = 0.024) and ethnicity (P = 0.048) contributed independently towards a higher prevalence of cardiac defects.

CONCLUSIONS

The prevalence of previously undiagnosed maternal cardiac structural abnormalities is significantly increased in women with high midtrimester uterine artery Doppler resistance indices. This observation has important consequences for the current and long-term medical care provided to these patients. Detailed maternal cardiac assessment with echocardiography may be required in migrant women with high uterine artery Doppler indices.

Emergency aortic valve replacement and Caesarian section in a primigravida with severe aortic stenosis: a case report

INTRODUCTION

Congenital bicuspid aortic valve with severe aortic stenosis (AS) is a rare condition (3-6% of patients with congenital heart disease). Pregnancy in these patients carries a high risk of maternal and fetal mortality. With advancing gestational age, these women may develop cardiac failure due to increased cardiorespiratory requirements. When medical therapy proves insufficient, cardiac surgery becomes mandatory to save the patient's life. Balloon valvuloplasty is only palliative treatment, the duration of benefit being only 6 months. Valve replacement is thus recommended. Cardiopulmonary bypass (CPB) surgery with valve replacement has been reported to carry a lower risk of maternal mortality (1.5-13%) but a very high fetal risk (16-40%). This paper reports the case of a 30-year-old primigravida with severe AS with bicuspid aortic valve and pulmonary congestion clinically uncontrolled, in whom CPB surgery and aortic valve replacement was performed as an emergency procedure, along with a lower segment Caesarian section.

CONCLUSION

The outcome of unrelieved severe symptomatic AS in pregnancy is poor. Multidisciplinary management is important to avoid deterioration in cardiac performance in parturients with severe AS. CPB during pregnancy carries a high risk to the fetus. Therefore, open heart surgery during pregnancy should be advised only in extreme emergencies (ie, heart failure refractory to conventional therapy).

[Pregnancy and cardiac surgery with cardiopulmonary bypass]

Heart disease during pregnancy necessitating cardiac surgery is potentially increasing maternal and fetal morbidity and mortality. Most patients know about their heart disease long before conception however the relation between the deteriorating cardiac function and the perinatal complications is not emphasized. Best possible results can be achieved by providing preconception counseling for cardiac patients. Consequently, heart-surgery can be performed before pregnancy thereby the maternal risk is lower and fetal loss or induced abortion can be avoided. The pregnant state is not optimal for cardiac surgery as the principal interest of the mother and the fetus is different. Cardiac surgery should be reserved only for saving the patient's life when medical therapy proves insufficient or when conservative management leads to acute heart failure. The multidisciplinary approach, correct risk assessment, diagnosis, operative indication, timing along with appropriate anaesthesia, extracorporeal circulation and alert monitoring of the uterine activity and fetal heart rate patterns make the intervention technically safe. Fetal monitoring is inevitable for prompt correction of operative conditions in case of impending hypoxemia. The perioperative fetal risk can be reduced by applying normothermia, high mean arterial pressure and cardiac index during the intentionally shortest intervention. Cardiac operation with cardiopulmonary bypass during pregnancy has become a relatively safe procedure for the mother but not for the baby.

Significance of retrograde diastolic uterine artery blood flow during regional anesthesia in instrumented pregnant sheep

BACKGROUND

We studied the interactions between uterine and placental hemodynamics during maternal hypotension in chronically instrumented fetal sheep. In addition, we investigated maternal hemodynamic characteristics, fetoplacental hemodynamics and fetal acid-base status when a retrograde diastolic uterine artery blood flow pattern is present during maternal hypotension.

METHODS

Invasive maternal and fetal hemodynamic parameters, uterine (Q(UtA)) and placental (Q(UA)) volume blood flows and acid-base values were examined in 24 chronically instrumented sheep at baseline and during epidural-induced maternal hypotension at 117-132 (term 145) days of gestation. Uterine artery blood flow velocity waveforms were obtained by Doppler ultrasonography.

RESULTS

Maternal hypotension decreased Q(UtA) without affecting Q(UA). During hypotension, eight out of 24 sheep demonstrated a retrograde diastolic blood flow velocity waveform pattern in the uterine artery. Maternal systolic, diastolic and mean arterial blood pressures were significantly lower in the retrograde group than in the antegrade group. No statistically significant differences in Q(UtA), Q(UA) and fetal blood gas values were detected between the two groups during hypotension.

CONCLUSIONS

An acute decrease in uterine artery volume blood flow during maternal hypotension is not compensated by increased placental volume blood flow. A retrograde diastolic blood flow pattern in the uterine artery is related to lower maternal arterial pressures, especially during diastole. A uterine artery retrograde diastolic blood flow pattern does not have any additional detrimental short-term effects on fetal acid-base status.

Emergency redo mitral valve replacement in a pregnant woman at third trimester: case report and literature review

Pregnancy carries significant physiological changes that demand more cardiac output, so structural cardiac disease can cause life-threatening complications. A woman had rheumatic mitral stenosis and underwent mitral valve replacement (MVR) with bioprosthesis 8 years prior to admission. She presented with dyspnea and leg edema at 30 weeks of gestation. Severe mitral stenosis caused by xenograft failure was noted on echocardiography. Management was conservative until a sudden onset of hemodynamic compromise requiring emergency redo MVR under normothermic cardiopulmonary bypass with intra-aortic balloon pump. Monitoring of fetal heartbeat and uterine contractions showed no significant abnormalities and the woman gave birth to a full-term baby by Cesarean section with postoperative warfarin therapy.

Emergency pulmonary embolectomy during the second trimester of pregnancy: report of a case

We report a case of acute massive pulmonary thromboembolism, which occurred during the second trimester of pregnancy in a 35-year-old woman with thrombocytopenia and anemia secondary to myelodysplastic syndrome. We performed successful emergency pulmonary embolectomy, under cardiopulmonary bypass, using argatroban as an anticoagulant. An intra-aortic balloon pump was used to maintain placental blood flow. The patient recovered completely and was later delivered of a healthy baby. Thus, pulmonary embolectomy saved both the mother and the fetus.

Fetal echocardiography: where are we?

This article reviews the indications, technique and benefits of fetal echocardiography. The impact of fetal echocardiography has become evident with better surgical outcome of infants with prenatal diagnosis of congenital heart disease. A major use of this technique has also been shown in the field of fetal arrhythmias. Fetal echocardiography is not only used to diagnose a specific type of arrhythmia, it is also very helpful in assessing the effect of the arrhythmia on the fetus and in guiding transplacental therapy. However it is important to remember that even experienced echocardiographers can make both false positive and false negative diagnosis of congenital heart disease. As fetal cardiac interventions including fetal cardiac surgery loom on the horizon, fetal echocardiography assumes further importance.

Frontiers in fetal cardiovascular disease

This article reviews the state of the art in prenatal cardiovascular imaging, the elucidation of regional vascular flow patterns in the developing fetus and what can be learned from these flow patterns, the new clinical practice systems being that are being implemented to deal with the fetal patient and its family, and the prospects for fetal surgery.

Outcome of cardiovascular surgery and pregnancy: a systematic review of the period 1984-1996

The outcomes of cardiovascular operations during pregnancy, at delivery, and post partum were reviewed from published material in the period 1984-1996. Surgery during pregnancy resulted in fetal-neonatal morbidity and mortality of 9% and 30%, respectively, and in maternal morbidity and mortality of 24% and 6%, respectively. Duration of pregnancy at surgery and duration and temperature of cardiopulmonary bypass did not influence fetal-neonatal outcome. Maternal complications and mortality of surgery immediately after delivery were 29% and 12%, respectively, and for surgery performed with a postpartum interval the respective rates were 38% and 14%. Hospitalization after week 27 of gestation and extreme emergency contributed significantly to poor maternal outcome. Maternal deaths were reported in 9% of valvular procedures and in 22% of aortic or arterial dissection repairs and pulmonary embolectomies. Fetal-neonatal risks of maternal surgery during pregnancy are high and unpredictable. Maternal risks of cardiovascular procedures during pregnancy are moderate, significantly increase if an operation is performed at or after delivery, and, overall, should be considered as higher than those in nonpregnant cardiovascular surgical patients.