Successful pregnancy in a patient with univentricular heart and pulmonary stenosis.

Univentricular heart or single ventricle heart is a rare and complex congenital heart disease (CHD). We report the successful management of a parturient with a single ventricle, and pulmonary stenosis. The univentricular heart is discussed in detail and the maternal and fetal outcome in pregnant women with CHD is reviewed.

INTRODUCTION

Congenital heart disease (CHD) occurs in 0.8% of newborns around the world. Advances in medical and surgical treatments over the past decades have led to more than 85% of these newborn surviving to adulthood. Half of these patients are women; the majority of them of childbearing age.[1] The combination of cardiac disease and pregnancy carries considerable risk for both mother and child, thereby posing a great challenge to the obstetrician. Univentricular heart or single ventricle heart accounts for 3.2% of congenital cardiac abnormalities.[2] Successful pregnancy associated with the condition is rare and with recognised maternal mortality.[34] We report a case of a successful pregnancy in a 23-yr-old woman with univentricular heart and pulmonary stenosis.

CASE REPORT

A 25-year-old primigravida with 34 weeks of gestation with univentricular heart and pregnancy-induced hypertension was admitted with preterm labour. She was diagnosed to have univentricular heart at the age of 10 years. Surgery was then proposed but declined by her parents. Despite the severity of the diagnosis she remained asymptomatic and in stable condition. Oxygen saturation varied between being 88% and 92%. Her exercise tolerance was normal during her adolescence. However, since last two years her exercise tolerance was gradually reduced and her activities were minimal. Her first visit to the antenatal clinic was at 10 weeks of amenorrhea and a single intrauterine pregnancy with positive fetal heart beat was confirmed with transvaginal ultrasound. Both she and her husband were informed in detail about the risks of her pregnancy. Following this she had regular obstetric care combined with cardiological assessment, and remained well.

Detailed anatomy scan at 20 weeks of pregnancy revealed no abnormalities of the fetus. Emphasis was given on the examination of fetal heart but there was no obvious cardiac anomaly present. Repeat scan with Doppler at 28 weeks of pregnancy showed evidence of presystolic notching in bilateral uterine arteries suggestive of early uteroplacental insufficiency. She was diagnosed to have pregnancy-induced hypertension at 31 weeks of gestation and was started on alpha methyldopa.

During pregnancy the hemoglobin level ranged between 12.0 and 14.0 g/dl. Echocardiography revealed single ventricular of LV morphology with moderate valvular pulmonary stenosis. There was normal veno-atrial connection. Two atria were connected via two atrioventricular valves to a single ventricle (of the left type) with an EF of 60%. An anterior rudimentary outlet pouch was giving rise to pulmonary artery, whereas the aorta originated from the single ventricle. Large non-restrictive bulboventricular foramen was present.

The pulmonary valve was thickened and other valves were structurally normal. On admission, her BP was 110/86 mmHg. SpO2 measured 92%. Patient presented with advanced preterm labour. A preterm live female, 1200 g infant was born with Apgar scores 8, 9, and 10 at 1, 5, and 10 mins, respectively. The estimated blood loss was 150 ml and the patient was covered with intravenous amoxicillin and gentamicin. Pain relief was achieved with oral diclofenac. The patient made an uneventful recovery and was discharged home.

DISCUSSION

Univentricular or single ventricle heart applies when two atria are related entirely or almost entirely to one ventricular compartment, with total mixing of systemic and pulmonary venous return. The single ventricle may have left, right, or indeterminate ventricular anatomic characteristics. The aorta and pulmonary artery both arise from this single chamber, although one of them may originate from a rudimentary outflow chamber. The aorta may be posterior, anterior (malposition), or side by side with the pulmonary artery and either to the right or to the left.[5] Patients who reach adulthood have either pulmonary stenosis or pulmonary vascular disease that permits adequate but not excessive pulmonary blood flow.

Pregnant women with cyanotic CHD are at increased risk for maternal and neonatal complications. Fortunately, as long as their ventricular function is normal they tolerate pregnancy well. Maternal heart failure, pregnancy induced hypertension, pulmonary oedema, endocarditis, arrhythmias, embolism, stroke, hemorrhage, thrombosis, and maternal death are the risks of these pregnancies.[4] In uncorrected or palliated pregnant patients with cyanotic CHD the usual pregnancy associated fall in systemic vascular resistance and rise in cardiac output exacerbate right to left shunting leading to increased maternal hypoxemia and cyanosis.[6]

A study by Presbitero et al. examining the outcomes of 96 pregnancies in 44 women with a variety of cyanotic CHD reported a high rate of maternal cardiac events (32%), including one death, prematurity (37%), and a low live birth rate (43%).[7] The main determinants of live birth were the arterial oxygen concentration at rest (>85%) and the hemoglobin concentration at the beginning of pregnancy (<20 g/dL). They concluded from the study that women with cyanotic CHD can go through pregnancy with a low risk to themselves, with frequent treatable complications, but there is a high incidence of miscarriage, premature births, and low birth weights.[7] Other fetal complications such as small-for-gestational-age and respiratory distress syndrome are often associated with univentricular heart disease.[4] Therefore, serial scans to monitor fetal growth and wellbeing should be performed because of the increased risk of preterm labour or intrauterine growth retardation (IUGR). In addition, a detailed fetal scan to exclude fetal cardiac anomaly is necessary due to the increased risk of cardiac anomalies in infants born to mothers with CHD.[34] Most complications arise from the increase in right to left shunting during pregnancy resulting in further hypoxemia and acidosis. There is a direct relationship between chronic hypoxemia, polycythemia, uteroplacental insufficiency, and pregnancy outcome.[6]

Hospitalization in a patient with univentricular heart is necessary if symptoms from the cardiovascular system arise or there is evidence of IUGR that requires regular assessment. Cardiac decompensation and other maternal complications with univentricular heart are commonly seen during and after delivery, as several factors lead to rapid increase of the pulmonary-to-systemic shunt. These factors include reduced peripheral resistance or due to diminution of venous return induced by blood loss or vena cava syndrome, or due to an increased pulmonary vascular resistance caused by microthrombosis and hypoxemia.[2]

Good outcomes have been reported following vaginal delivery or caesarean section in women with a univentricular heart.[28] No association between the type of delivery and peripartum cardiac event rate was found in a multicentre study of pregnancy outcomes in women with heart disease.[9] In general, vaginal delivery is recommended in pregnant women with univentricular heart who are considered functionally normal unless there are obstetric indications for caesarean section.[46]

During labour, the patient with heart disease should be kept in a semi-recumbent position with lateral tilt to attenuate hemodynamic fluctuations associated with contractions in the supine position. Forceps or vacuum extraction will shorten the later part of the second stage of labour and reduce need for maternal expulsive efforts.[46] Long induction in women with unfavourable cervix should be avoided because of the risk of complications.[610] Induction near term may be justified to plan delivery in complicated cases requiring optimal medical support.[3] Although intravenous analgesics provide satisfactory pain relief for some women, continuous epidural analgesia is recommended in most cases.[6] Care must be taken to achieve meticulous haemostasis, maintain good hydration, and to avoid vasodilation (for example, with high dose epidural) and air emboli through venous lines. All patients with cyanotic CHD must receive antibiotic cover during their hospital stay.[6]

CONCLUSION

In conclusion, pregnancy in patients with univentricular heart is possible, but is associated with a high incidence of maternal cardiac complications, premature birth, and spontaneous abortion. Careful interdisciplinary management between the cardiologist, obstetrician, anesthetist, and neonatologist throughout the pregnancy, delivery, and postpartum period is necessary for a good maternal and fetal outcome.