Background: Cor Triatriatum Sinistrum (CTS) is a very rare condition comprising 0.1-0.4% of congenital heart disease. It is characterised by a fibromuscular septum separating the left atrium into two chambers. It can lead to arrhythmias, thrombosis, pulmonary oedema and pulmonary hypertension. The condition is usually diagnosed in infancy however haemodynamic changes associated with pregnancy can trigger decompensation in undiagnosed CTS.
Case Summary: A 24-year-old female (G8P3) presented to a regional NSW hospital at 25 weeks gestation with pulmonary oedema and a suspected viral respiratory infection. She was transferred to our tertiary facility for ongoing management. A transthoracic echocardiogram demonstrated CTS (membrane orifice < 0.5cm2) with profoundly dilated right ventricle, severe tricuspid incompetence and severe systemic-level pulmonary hypertension. Obstetric ultrasound confirmed single live intrauterine pregnancy with normal growth and wellbeing. Prophylactic enoxaparin, metoprolol and frusemide were commenced. Post-stabilisation she was monitored closely as an outpatient. At 31 weeks gestation the patient was re-admitted and administered betamethasone for fetal lung maturation. An induction of labour (IOL) with mechanical ripening and artificial rupture of membranes was planned for 34 weeks gestation. Iloprost was administered throughout labour. Early regional anaesthesia with slow titration was instituted to minimise haemodynamic effects. Oxytocin was deliberately not utilised due to side-effect profile worsening cardiac function. Labour did not establish and the patient underwent an uncomplicated lower-segment caesarean section with invasive monitoring and postoperative transfer to ICU. Low dose metoprolol was continued throughout and estimated blood loss was 350ml. A healthy 2.5kg female infant was delivered with normal cord blood gases. CTS was managed with resection of the membrane and mitral annuloplasty 3 months post-delivery. After 4 years of follow-up the patient is well with normal cardiac function and pulmonary pressures.
Conclusion: With careful management successful delivery was possible in a patient with CTS and severe pulmonary hypertension.