GO Okunoye, CA Alexander, R Campbell 1
Simpson Centre for Reproductive Health Royal Infirmary Edinburgh, EH16 4SA, UK
1 Borders General Hospital Melrose, Scotland, UK
E mail: okunoyezaza@yahoo.co.uk
SMJ 2008 53(1): 60
Introduction
The
association between cardiac disease in pregnancy and a relatively increased risk
of maternal and perinatal morbidity and mortality has long been recognised ¹.In
the past, pregnancy in women with severe congenital cardiac anomaly was rare as
these women were advised against pregnancy and many died before reaching child
bearing age. We describe the case of a successful pregnancy after surgically
corrected complete transposition of the great arteries.
Case
Report
This
20 year old woman was diagnosed with transposition of the great arteries (TGA)
at birth .She underwent an atrial switch procedure at nine months of age
(Mustard’s) to correct the anomaly. Her growth and development was normal
through childhood and she had no history of cardiac decompensation .She was not
on any regular medication and was discharged from routine cardiology follow up
at 12 years of age.
This
pregnancy was unplanned; hence she received no specific pre-pregnancy
counselling. She had no family history of congenital heart disease. Cardiology
review at 12 weeks gestation revealed no remarkable findings on clinical
examination. She was normotensive with a New York Heart Association (NYHA) class
of І. There were no changes to the 12-lead electrocardiogram (ECG).An
echocardiogram showed normal right ventricle (functional left) and normal left
ventricle (functional right) with good systolic function.
A
detailed fetal anomaly scan at 20 weeks and a fetal echocardiogram at 24 weeks
revealed no abnormalities. Growth scans were arranged for 28 and 32 weeks. She
was reviewed at the Obstetric Anaesthesia clinic at 26weeks gestation.
She developed Pregnancy Induced Hypertension (PIH) at 28 weeks and was commenced on oral antihypertensive (Labetalol) with enhanced antenatal surveillance. At 32 weeks, her blood pressure control was sub optimal despite maximum dose of oral Labetalol. Renal and liver function tests as well as the haematological indices were normal and she remained asymptomatic with no proteinuria.
Ultrasound scan at 33weeks gestation revealed static fetal growth with reduced amniotic fluid index (<5cm) and raised umbilical artery resistance index. Cardiotocograph (CTG) was normal. Delivery was contemplated and antenatal steroids were administered. Discussion of care of the baby after delivery was undertaken by the neonatologists.
A
repeat echocardiogram carried out at 33weeks gestation showed a dilated right
ventricle (functional left) with poor systolic function. The left ventricle
(functional right) was normal. Aggressive control of blood pressure with the
addition of a second line antihypertensive (Nifedipine) was carried out followed
by caesarean section under epidural anaesthesia.
A live baby girl weighing 1.46kg (3rd centile for gestation) was delivered in good condition with apgar scores of 8 and 9 at one and five minutes respectively. The baby was admitted to the neonatal unit where it made very good progress.
She
remained stable postpartum and was commenced on Ramipril (Angiotensin converting
enzyme inhibitor) and was gradually weaned off Labetalol. She was discharged
home on day 5.
Cardiology
review three months postpartum revealed a normal echocardiogram .She remained on
a small dose of Ramipril and the importance of pre-pregnancy counselling in a
subsequent pregnancy was emphasised.
Discussion
The popularisation of atrial switch procedures in the mid 1970s to correct complete TGA has resulted in women born with this cardiac anomaly reaching child bearing age ².TGA accounts for about 4% of all congenital heart diseases. After an atrial switch procedure the anatomical right ventricle works as the systemic ventricle. Although this is associated with an increased risk of congestive heart failure and supraventricular tachycardia, the long term (20-30 years) outcome for patients surviving the Mustard operation has been favourable with up to 76% of survivors being New York Heart Association class 1 after 28 years. This does not however imply a normal life expectancy as the risks of right ventricular dysfunction and late sudden deaths increase afterwards ³ˉ. Most patients lead an entirely normal childhood and grow into adulthood with a natural expectation to be able to have their own children.
Pregnancy
after Mustard’s procedure presents a unique challenge because of the concerns
about the possible effect on the right ventricular function which is the
functional left ventricle .
Pre-pregnancy
counselling and assessment of cardiac function is imperative in these patients
.This is best carried out in a multi disciplinary setting with direct inputs
from Cardiologists, Obstetricians and Anaesthetists who will then be responsible
for looking after the woman in pregnancy. This will afford the patient an
opportunity to make an informed choice prior to embarking on pregnancy. In
reality however most pregnancies are unplanned, therefore urgent assessment must
be carried out as soon as pregnancy is confirmed as in this case. As a minimum
this should include a clinical examination of the cardiovascular system, a
12-lead ECG, a transthoracic echocardiogram and a functional classification
based on the NYHA.
Antenatal care in a multidisciplinary team streamlines the process of decision making, ensures better communication between professionals and the patient thus optimising the chance of a good outcome.
A baseline echocardiogram is essential to assess ventricular function and this should be repeated at least in each trimester in patients with pre-existing right ventricular dysfunction to detect further deterioration in cardiac function and provide the basis for discussion regarding the timing and mode of delivery. These patients must be counselled that pregnancy induced ventricular dysfunction is sometimes irreversible .The frequency of antenatal visits is variable and enhanced surveillance in the third trimester to detect Pre-eclampsia and signs of cardiac decompensation is advocated.
Routine fetal echocardiogram should be offered to these women as 2-5% of their offspring will potentially have a detectable cardiac anomaly. A higher incidence of hypertension and pre-eclampsia is expected in these patients hence the need for closer surveillance especially in the third trimester ۹. Fetal growth monitoring is essential in pregnancies complicated by hypertension because of the associated risk of growth restriction. In the absence of specific obstetric complications there is no contraindication to vaginal delivery. However due to the inherent physiologic circulatory changes in pregnancy, the risk of cardiac decompensation is highest in the peripartum period. Therefore a shortened second stage, avoidance of ergometrine for the management of third stage, careful attention to fluid balance and a low threshold for the use of invasive monitoring will reduce the risk of cardiac decompensation.
In those pregnancies complicated by pre-eclampsia, the aggressive control of blood pressure followed by delivery when appropriate will reduce the risk of long term right ventricular dysfunction. Anaesthesia for operative deliveries is crucial to avoid wide fluctuations in blood pressure with its attendant risks. The type of anaesthesia should be determined by the uniqueness of each case by an experienced anaesthetist.
Irrespective of the mode of delivery, it is essential to observe these patients closely in the immediate post partum period and a careful assessment of the need for low molecular weight heparin for thromboprophyllaxis should be made.
Follow up echocardiogram at three and six months post partum is suggested to detect the group of patients with residual irreversible right ventricular dysfunction and provide a basis for counselling regarding a subsequent pregnancy.
Conclusion
Increasing
number of women with surgically corrected congenital cardiac anomaly will now be
embarking on pregnancy. The limited experience in this area requires a greater
emphasis on pre-pregnancy counselling with primary care physicians playing a
pivotal role by identifying and referring these women appropriately. Though
challenging, a good pregnancy outcome can be expected in these women when
managed in a multidisciplinary team as amply demonstrated in this case. It must
be appreciated that one successful pregnancy does not guarantee another without
the same level of clinical vigilance. Pregnancy in this group of women should
always be treated as high risk regardless of previous obstetric performance.
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