53.2 Gynaecological, obstetric, and neonatological aspects

Pregnancies in women with cardiopulmonary disease pose a higher risk of maternal cardiovascular events and fetal compromise. Prenatal diagnostics to detect fetal malformations and examination of the fetoplacental haemodynamic state are therefore required.

A sensitive surveillance of the fetal state in the third trimester can be performed with computerized heart rate variation.¹

The ultrasound detection of fetal malformations including congenital heart defects is already possible in the first trimester but shows a higher sensitivity between 18 and 22 weeks of gestation. Doppler velocimetry provides a non-invasive measure of the fetoplacental haemodynamic state. An increased resistance of the umbilical artery correlates to placental insufficiency and consecutive adverse fetal outcome. Patients with absent or reversed end-diastolic flow velocity of the umbilical artery must be admitted to a perinatal centre and lung maturation is indicated before 34 completed weeks. After completion of the lung maturation within 48 h, caesarean section must be considered. A decreased resistance of the middle cerebral artery, a pathological cerebroplacental ratio, and an absent A-wave of the ductus venosus detect severe fetal impairment (Figure 53.2.1). Technically, the whole vessel of the middle cerebral artery close to the ultrasound probe has to be imaged and measured on its origin with an angle of insonation of zero. A pathological biophysical profile (reduced fetal movement, tone, and breathing) may also indicate fetal compromise.

The same restrictions that apply for coronary angiography are relevant. The best time is considered to be the fourth month, after completion of the organogenesis, with the placental perfusion requirements weakly depending on maternal circulation conditions.

Maternal mortality during cardiopulmonary bypass is similar to that in non-pregnant women. Surgical interventions after 13 weeks may decrease the abortion rate. However, because of a considerable fetal morbidity and mortality, cardiac surgery is only recommended in life-threatening cases. Neonates born before 28 weeks have a high mortality rate of approximately 20%, but the morbidity rate depends tremendously on the exact gestational age: between 24 and 28 completed weeks, every day increases the survival rate without major complications such as retinopathy, necrotizing enterocolitis, intraventricular haemorrhage, and bronchopulmonary dysplasia by 3%. Corticosteroids for lung maturation should be administered before surgery until 34 completed weeks.

Pump flow greater than 2.5 L/min/m² and perfusion pressure higher than 70 mmHg are mandatory to maintain adequate uteroplacental blood flow. See Figure 53.2.2 and Figure 53.2.3.

An optimized maternal haematocrit, normothermic perfusion, and avoidance of hypocapnia that is responsible for uteroplacental vasoconstriction is recommended.

Spontaneous delivery after 37 weeks is favourable in patients with normal cardiac function and fetal well-being. However, induction of labour is preferred when the functional adequacy of the maternal heart is uncertain.

Management of labour and postpartum surveillance require interdisciplinary expertise and delivery in a perinatal centre. To guarantee optimized conditions with the presence of extracorporeal membrane oxygenation therapy or open-heart surgery, caesarean sections in patients with unstable cardio-pulmonary diseases might be performed in the operating theatre of a cardiac surgery centre. For lack of guidelines, individual risks can be assessed with the World Health Organization risk score.

Caesarean sections pose an increased risk due to challenging anaesthesiological management, thrombotic events, and higher blood loss in patients requiring anticoagulants.

The management of labour includes induction, pain therapy, and assisted delivery taking place under controlled conditions. Caesarean delivery should be reserved for obstetrical indications or preterm labour in patients on oral anticoagulants, with an aortic root larger than 45 mm, severe aortic stenosis, with pulmonary hypertension (including Eisenmenger syndrome) or with decompensated heart failure.

Prolonged labour should be avoided. Oxytocin and artificial rupture of the membranes are only indicated if the Bishop score is favourable. Cervical ripening may be achieved mechanically by balloon catheters or laminaria and is preferable in patients with cyanosis, where a drop in systemic vascular resistance and/or blood pressure would be detrimental. Labour induction with prostaglandins poses the risk of blood pressure fluctuations, coronary vasospasm, and arrhythmias. Their profound effects on the blood pressure must especially be considered in active cardiovascular disease.

The fetal head should be in cephalic presentation. During labour, the woman should be placed in a left-lateral position to attenuate the haemodynamic fluctuations. Maternal pushing that provokes the unwanted effects of the Valsalva manoeuvre can then be reduced with a pelvic outlet assisted delivery by forceps or vacuum extraction.

Warfarin prior to 8 weeks of pregnancy can lead to fetal loss and anomalies and haemorrhagic events of the fetus can occur at term. Low-molecular-weight heparin or unfractionated heparin should therefore be given until 13 weeks and at term. Unfractionated heparin that can be antagonized during labour is the favourable anticoagulant until 4–6 h before and immediately after delivery.

Systemic arterial pressure and maternal heart rate are monitored. Pulse oximetry and continuous electrocardiogram monitoring are utilized as required. A Swan–Ganz catheter is reserved for selected cases and should be continued in the immediate postpartum period because of large intravascular volume shifts.

Epidural anaesthesia is recommended to reduce pain-related sympathetic activity and the urge to push. However, patients that are sensitive to the subsequent reduced venous return and preload must be monitored carefully. Contraindications are a low platelet count (<50/nL), anticoagulation, and local infections.

Slow oxytocin infusion is administered after placental delivery to prevent haemorrhage. Prostaglandin analogues lead to efficacious uterine contractions but may increase the pulmonary artery pressure. Methylergometrine may lead to vasoconstriction and hypertension and is contraindicated.

There is no general contraindication for patients with cardiovascular disease to breastfeed. However, peripartum cardiomyopathy has been associated with prolactin excretion. Delactation with dopamine receptor agonists is therefore recommended in these patients.