Complex Cyanotic Congenital Heart Disease in Pregnancy: Survival With Unrepaired Pulmonary Atresia and Ventricular Septal Defect – A Case Report

Introduction

Pulmonary atresia with ventricular septal defect (PAVSD) represents a severe conotruncal malformation characterized by complete obstruction of the right ventricular outflow tract in the presence of a large, usually malaligned ventricular septal defect and an overriding aorta. In this lesion, pulmonary blood flow depends on systemic-to-pulmonary collateral vessels rather than a native main pulmonary artery. Historically, this anatomy was classified as “Type IV truncus arteriosus” under the Collett and Edwards system ¹ ; however, contemporary embryologic and morphologic data have established that so-called Type IV truncus arteriosus is pathophysiologically distinct and is now recognized as PAVSD and major aortopulmonary collateral arteries rather than true truncus arteriosus. ²

True truncus arteriosus involves a single truncal valve and a common arterial trunk supplying the systemic, pulmonary, and coronary circulations. In contrast, PAVSD lacks a true truncal valve and main pulmonary artery, and the pulmonary arteries may arise independently from the descending aorta, aortic arch, or systemic collateral vessels. This distinction carries important implications for surgical strategy, long-term outcomes, and adult congenital heart disease (CHD) management.^3,4

Without early surgical intervention, PAVSD carries high mortality in infancy. Survival into adulthood without repair is rare and depends on the adequacy and balance of systemic-to-pulmonary collateral circulation. Unrepaired CHD remain at substantial risk for chronic hypoxaemia, secondary erythrocytosis, heart failure, arrhythmias, and thromboembolic complications. ⁵

Pregnancy imposes profound cardiovascular stress that may destabilize cyanotic CHD. Plasma volume expansion and reduced systemic vascular resistance increase right-to-left shunting, potentially worsening hypoxaemia. Guidelines classify cyanotic CHD with resting oxygen saturation below 85% as modified World Health Organization class IV, a category in which pregnancy is generally contraindicated because of high maternal morbidity and mortality risk. ⁶ In addition to maternal cardiovascular complications, fetal risks include miscarriage, intrauterine growth restriction, prematurity, and perinatal mortality.^6,7

Despite these well-established risks, women with undiagnosed CHD in low- and middle-income settings may reach reproductive age without prior cardiac evaluation, preconception counselling, or risk stratification. This gap in early detection and specialized CHD care contributes to preventable maternal and neonatal complications.

We report the case of a 22-year-old pregnant woman with previously undiagnosed PAVSD and systemic-to-pulmonary collateral supply who presented in advanced heart failure during the third trimester. Her clinical course was complicated by postpartum haemorrhage and subsequent ischaemic stroke. This case highlights the diagnostic challenges of unrepaired complex CHD, the extreme maternal risk associated with cyanotic lesions during pregnancy, and the need for multidisciplinary management and improved women’s cardiovascular health surveillance in resource-limited settings. The reporting of this study conforms to the CARE guideline ⁸ (Supplementary File 1).

Case Presentation

A 22-year-old woman at 32 weeks’ gestation by last menstrual period presented with five days of progressive dyspnoea, worsening on minimal exertion and accompanied by bilateral lower limb swelling and marked fatigue. Two days before admission, she reported per-vaginal fluid leakage and reduced fetal movements. She denied fever, chronic hypertension, diabetes mellitus, or known cardiac disease. Her obstetric history was notable for three consecutive intrauterine fetal deaths at approximately eight months’ gestation in prior pregnancies (ranging between the 28^th and 34^th weeks gestation), none of which had been evaluated for underlying maternal cardiovascular pathology.

On examination, she appeared chronically ill and was dyspnoeic at rest, consistent with New York Heart Association (NYHA) functional class IV. She had conjunctival pallor, central and peripheral cyanosis, grade IV digital clubbing, and bilateral pitting pedal oedema. Her blood pressure measured 109/87 mmHg, pulse rate was 94 beats per minute and regular, and oxygen saturation was 74% on room air. Cardiac examination revealed a displaced apex beat, a hyperdynamic precordium, a loud single second heart sound, and a holosystolic murmur best heard along the left sternal border. Fetal heart rate was 152 beats per minute.

We administered supplemental oxygen via face mask and intramuscular dexamethasone 24 mg for fetal lung maturation. Continuous telemetry showed sinus rhythm without atrial fibrillation or other sustained arrhythmias. Given her progressive heart failure and severe hypoxaemia, a multidisciplinary team comprising cardiology, obstetrics, anaesthesia, and neonatology recommended expedited delivery for maternal indication.

She underwent caesarean delivery under spinal anaesthesia with non-invasive haemodynamic monitoring. No vasopressor support was required intraoperatively. Estimated blood loss during caesarean delivery was approximately 600–700 mL. She delivered a live male infant weighing 1.6 kg (z-score -1.08; SD ∼0.26 kg). Apgar scores were 8 at one minute and 9 at five minutes. The neonate required no supplemental oxygen and was admitted to the neonatal unit for prematurity-related monitoring. Enteral feeding was initiated with formula while the mother was in intensive care; breastfeeding began after maternal stabilization. The neonate remained clinically stable, had no detectable congenital anomalies, and was discharged after approximately one week. At six-month follow-up, growth and neurodevelopment were appropriate for corrected gestational age.

Within one hour of delivery, the patient developed severe postpartum haemorrhage refractory to uterotonics and required emergency total hysterectomy under general anaesthesia. The total blood loss during haemorrhage was not precisely quantified. She received one unit of packed red blood cells intraoperatively. Haemostasis was achieved, and she was transferred intubated to the intensive care unit.

Initial laboratory investigations showed haemoglobin 19.0 g/dL and haematocrit 60.3%, with normal renal function, liver enzymes, and coagulation profile. D-dimer measured 1.6 µgFEU/mL, interpreted cautiously in the context of pregnancy and the immediate postpartum state. We initiated intravenous furosemide 40 mg three times daily for volume overload and oral carvedilol 3.125 mg twice daily for ventricular rate and afterload modulation.

Chest radiography demonstrated cardiomegaly with prominent pulmonary vascular markings (Figure 1). Electrocardiography showed sinus rhythm without ischaemic changes. Transthoracic echocardiography revealed preserved left ventricular systolic function (ejection fraction 64%), a large perimembranous ventricular septal defect, complete pulmonary atresia, and absence of a main pulmonary artery. The aortic valve was of normal morphology being tricuspid. The left pulmonary artery appeared to arise from the aortic arch (Figure 2).OPEN IN VIEWER

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Figure 2.

Transthoracic echocardiography demonstrating a large perimembranous ventricular septal defect (panels A–C). Panel D shows the left pulmonary artery (LPA) arising from the aortic arch. No main pulmonary artery is visualized. Abbreviations: RV, right ventricle; LV, left ventricle; Ao, aorta; Asc Ao, ascending aorta; Desc Ao, descending aorta

Cardiac computed tomography angiography further defined the anatomy. It demonstrated an overriding aorta above a large malaligned ventricular septal defect with complete pulmonary atresia (Figure 3). The right pulmonary artery originated from the descending thoracic aorta, and the left pulmonary artery arose from the undersurface of the aortic arch. The pulmonary arteries were non-confluent, and no main pulmonary trunk was identified (Figure 4). These findings established the diagnosis of PAVSD and systemic-to-pulmonary collateral supply.OPEN IN VIEWER

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Figure 4.

Three-dimensional cardiac computed tomography reconstruction confirming pulmonary atresia with ventricular septal defect and systemic-to-pulmonary collateral supply. The left pulmonary artery arises from the aortic arch (panel A), and the right pulmonary artery arises from the descending thoracic aorta (panel B). No main pulmonary trunk is identified

After 48 hours, we extubated her successfully. Following diuresis and supplemental oxygen therapy, her oxygen saturation improved to 86% on room air. Peripheral oedema resolved progressively, and her dyspnoea improved to NYHA class II. She reported a lifelong history of exertional breathlessness since childhood that had been treated empirically with antibiotics and traditional remedies, without prior cardiac evaluation. We discharged her on carvedilol 6.25 mg twice daily and furosemide 40 mg once daily, with outpatient adult CHD follow-up arranged.

Ten days after discharge, she developed sudden-onset right-sided weakness and dysarthria. Brain computed tomography revealed an acute ischaemic infarction in the left basal ganglia involving the lenticulostriate artery territory (Figure 5). Continuous telemetry again showed no atrial fibrillation. A transthoracic bubble study demonstrated intracardiac right-to-left shunting consistent with her underlying anatomy. Cardiac computed tomography excluded intracardiac thrombus. Venous Doppler ultrasonography of the lower extremities showed no evidence of deep venous thrombosis.OPEN IN VIEWER

Given the absence of documented atrial fibrillation and no visible intracardiac thrombus, we initiated antiplatelet therapy with clopidogrel 150 mg daily as a loading regimen, followed by maintenance dosing. She had received prophylactic unfractionated heparin before delivery; however, the immediate postoperative haemorrhagic complication precluded early therapeutic anticoagulation in the postpartum period. She underwent supportive stroke care and physiotherapy, with gradual neurologic improvement. At two-week follow-up, her right-sided motor strength had nearly normalized, and we reduced clopidogrel to 75 mg daily. At six months postpartum, she reported no recurrent neurologic events and no dyspnoea at rest. Oxygen saturation remained in the mid-80% range on room air. A timeline of current events is shown as Figure 6.OPEN IN VIEWER

Discussion

This case illustrates survival into adulthood with unrepaired PAVSD and systemic-to-pulmonary collateral supply. Contemporary embryologic and morphologic data confirm that PAVSD lacks a true truncal valve and main pulmonary artery; pulmonary perfusion depends on systemic collateral vessels or direct systemic arterial origins of the branch pulmonary arteries. ² This distinction is clinically relevant because long-term complications and surgical considerations differ substantially from those of true truncus arteriosus.

Supplementary File 2 summarizes the previously reported pregnancies in unrepaired PAVSD. Across the published cases, maternal and neonatal outcomes were variable, and only a small number involved severe cyanosis comparable to this case. Compared with these reports, the present case is notable for profound resting hypoxaemia (SpO₂ 74%), NYHA class IV heart failure, postpartum hysterectomy for haemorrhage, and a postpartum ischaemic stroke.

Without surgical repair in infancy, PAVSD carries high early mortality. Survival into adulthood is uncommon and depends on the adequacy and balance of systemic-to-pulmonary collateral flow. ³ Excessive pulmonary blood flow predisposes to pulmonary vascular disease, whereas insufficient flow results in profound hypoxaemia. Our patient’s lifelong exertional dyspnoea, digital clubbing, and severe resting hypoxaemia reflect longstanding cyanotic physiology that remained undiagnosed until pregnancy imposed additional haemodynamic stress. ⁵

Our patient’s resting saturation of 74% places her unequivocally in modified World Health Organization class IV. Risk prediction models further underscore this risk profile. The CARPREG II score assigns significant weight to baseline cyanosis and NYHA class III–IV symptoms, both present in this patient. ⁹ The ZAHARA risk model similarly identifies cyanosis and prior cardiac events as major predictors of adverse maternal outcomes. ¹⁰ Retrospectively, her pregnancy represented a very high-risk gestation that ideally would have prompted strong preconception counselling against continuation.

Fetal risks also correlate with maternal oxygen saturation. When maternal oxygen saturation falls below 85%, live birth rates decline markedly, and the incidence of prematurity and fetal loss increases.^6,7 Her history of three prior late intrauterine fetal deaths likely reflects chronic maternal hypoxaemia and impaired uteroplacental oxygen delivery. The survival of the current neonate may reflect close inpatient monitoring and timely delivery rather than improved underlying physiology.

Normal pregnancy induces a 40–50% increase in plasma volume, a 30–50% increase in cardiac output, and a reduction in systemic vascular resistance.^5,6 These changes can exacerbate right-to-left shunting in cyanotic lesions because the fall in systemic vascular resistance favours systemic desaturation. Although pulmonary vascular resistance typically decreases during normal pregnancy, the fixed anatomy of PAVSD prevents effective augmentation of pulmonary blood flow. Consequently, hypoxaemia may worsen despite increased cardiac output.

Chronic hypoxaemia stimulates erythropoiesis and may lead to secondary erythrocytosis. In this case, haemoglobin measured 19.0 g/dL with a haematocrit of 60.3%, consistent with significant hypoxia-driven erythrocytosis. Elevated haematocrit increases blood viscosity and promotes platelet activation, endothelial dysfunction, and impaired microvascular flow, thereby predisposing patients to thromboembolic complications.^5,11

Pregnancy further modifies this physiology. Although plasma volume expansion typically produces physiologic haemodilution, women with complex cyanotic CHD may still develop marked erythrocytosis because chronic hypoxaemia strongly stimulates erythropoietin production. The coexistence of erythrocytosis and the hypercoagulable state of pregnancy therefore substantially increases thrombotic risk.^6,11 In this patient, the combination of severe cyanosis (SpO₂ 74%), marked erythrocytosis, postpartum hypercoagulability, and delayed initiation of anticoagulation following haemorrhage likely contributed to the development of ischaemic stroke ten days after delivery.

Guidelines generally favour vaginal delivery in women with cardiac disease to minimize blood loss and thromboembolic risk, reserving caesarean delivery for obstetric or urgent maternal indications.^6,7 However, severe maternal decompensation may necessitate expedited operative delivery. In our patient, progressive NYHA class IV symptoms and profound hypoxaemia justified caesarean delivery for maternal indication.

Regional anaesthesia is typically preferred in cyanotic CHD because it avoids airway manipulation and may provide gradual sympathetic blockade when carefully titrated.^6,7 Abrupt reductions in systemic vascular resistance can worsen right-to-left shunting; therefore, anaesthetic management requires meticulous haemodynamic monitoring. In this case, spinal anaesthesia proceeded without vasopressor requirement, although the subsequent postpartum haemorrhage required emergent hysterectomy under general anaesthesia. The haemorrhagic complication introduced a competing risk profile by limiting early postoperative anticoagulation.

The immediate postpartum period represents a time of major cardiovascular transition. Autotransfusion from uterine involution and mobilization of extracellular fluid increase preload, while persistent hypercoagulability heightens thrombotic risk.^6,7 Careful monitoring during the first 48 hours postpartum is essential in high-risk CHD patients.

Thromboembolic complications occur in up to 10–15% of pregnancies complicated by cyanotic CHD.^6,7 Mechanisms include chronic hypoxaemia-induced endothelial dysfunction, secondary erythrocytosis, venous stasis, paradoxical embolism through intracardiac shunts, and postpartum hypercoagulability.^5,11 Our patient developed an ischaemic basal ganglia infarction 10 days postpartum. Continuous telemetry excluded atrial fibrillation, and cardiac computed tomography did not identify intracardiac thrombus. Transthoracic bubble study confirmed persistent right-to-left shunting, raising the possibility of paradoxical embolism despite negative lower extremity Doppler findings. The absence of documented atrial fibrillation and the recent major haemorrhagic event influenced the decision to initiate antiplatelet therapy rather than immediate full anticoagulation, consistent with contemporary ischaemic stroke management principles. ¹² Haematocrit levels above 55% are associated with increased blood viscosity and higher thromboembolic risk in cyanotic CHD. ¹¹ The preceding postpartum haemorrhage likely delayed optimal thromboprophylaxis, illustrating the difficult balance between haemorrhagic and thrombotic risk in cyanotic CHD.

In the perinatal management of cyanotic CHD, the prevention of thromboembolism necessitates a paradigm shift away from aggressive haematocrit reduction. Guidelines strongly discourage routine prophylactic phlebotomy, as recurrent ‘bolus letting’ frequently induces iron deficiency; this results in microcytic, rigid erythrocytes that paradoxically increase whole-blood viscosity and the subsequent risk of ischaemic stroke. ⁶ If symptomatic hyperviscosity necessitates intervention, isovolumetric venesection, rather than simple phlebotomy, should be employed to ensure haemodynamic stability and prevent microvascular ‘sludging’. ³ Furthermore, heparin administration should not be initiated solely to treat secondary erythrocytosis, given the heightened risk of haemorrhage in this population due to intrinsic coagulopathy and platelet dysfunction; its use remains reserved for specific indications such as mechanical valves or concurrent atrial arrhythmias. ¹³ Modern stroke prevention in this high-risk patient instead prioritises the maintenance of an iron-replete state and meticulous peripartum hydration to optimise red cell deformability and avoid haemoconcentration. ⁴

Three key lessons emerge. First, complex CHD may remain undiagnosed in women of reproductive age in resource-limited settings, presenting only when the haemodynamic stress of pregnancy unmasks advanced disease. Systematic cardiovascular evaluation and preconception counselling are essential to prevent avoidable maternal morbidity and recurrent fetal loss. Second, the physiologic changes of pregnancy, including plasma volume expansion and reduced systemic vascular resistance, can exacerbate right-to-left shunting and precipitate heart failure in cyanotic lesions. Multidisciplinary planning with cardiology, obstetrics, anaesthesia, and neonatology is critical to guide delivery strategy and peripartum monitoring. Third, the postpartum period represents a particularly vulnerable window, during which hypercoagulability and haemodynamic shifts may precipitate thromboembolic events. Clinicians must carefully balance bleeding and thrombosis risk, especially after obstetric haemorrhage, and individualize thromboprophylaxis strategies.

This case underscores systemic gaps in cardiovascular screening among women of reproductive age in low- and middle-income settings. The patient’s lifelong symptoms, recurrent fetal losses, and overt cyanosis went unrecognized as manifestations of complex CHD. Limited access to echocardiography, lack of structured preconception counselling, and absence of specialized adult CHD services contribute to preventable maternal morbidity. Integration of cardiovascular assessment into antenatal care pathways and improved referral networks for CHD may mitigate such outcomes.

Conclusion

This case demonstrates survival into adulthood with unrepaired PAVSD and systemic-to-pulmonary collateral supply, a rare and high-risk congenital lesion. Pregnancy in the setting of complex cyanotic CHD, particularly with resting oxygen saturation below 85%, carries extreme maternal and fetal risk and falls within modified World Health Organisation class IV, where pregnancy is generally contraindicated. Ultimately, this case underscores the need for integrated adult CHD services within women’s health systems, particularly in low- and middle-income regions, to improve preconception risk assessment, pregnancy counselling, and long-term cardiovascular follow-up for high-risk women.

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