Pulmonary regurgitation is a common consequence of repair of tetralogy of Fallot in particular where more extensive right ventricular outflow and pulmonary artery reconstruction were needed to relieve the original obstruction. It is generally well tolerated by patients and may be asymptomatic from the cardiac viewpoint for several decades. However, with time, pulmonary regurgitation results in right ventricular dilatation, right heart dysfunction, arrhythmia, heart failure and death. In the last 15 years, a lot of progress has been made regarding the timing of reoperation or transcatheter intervention to replace the pulmonary valve. This is now more commonly offered at an earlier stage, based on investigations and before patients become symptomatic. The status of the right ventricle is a more important arbiter of pregnancy-related risk than the degree of pulmonary regurgitation (Fig. 7.2). If both right and left ventricular functions are preserved, pregnancy is likely to be well tolerated despite severe pulmonary regurgitation. However, the risks of pregnancy are increased in the setting of pulmonary regurgitation with right ventricular dilatation and dysfunction and associated clinical symptoms (New York Heart Association class II or higher) [7]. As pregnancy results in an increased circulating volume, this further compounds the right ventricle volume overload. In some cases, irreversible cardiac remodelling can develop especially during the late stage of pregnancy.

When planning pregnancy, a full assessment of the impact of any pulmonary regurgitation should be made. If criteria are met for elective pulmonary valve replacement, this may be preferable prior to embarking on pregnancy. The decision regarding indications for elective pulmonary valve replacement to treat asymptomatic pulmonary regurgitation is individualised as for the patient not planning pregnancy. Echocardiography is the routine test of choice for screening patients with significant pulmonary regurgitation and right heart dilatation and for assessing ventricular function (Figs. 7.3, 7.4). Cardiovascular magnetic resonance imaging is used for accurate right ventricular volume and function assessment and cardiopulmonary exercise testing for objective measure of exercise capacity, and heart assessment also includes 12-lead electrocardiogram and chest x-ray for cardiothoracic ratio. Pregnancy planning may bring forward detailed heart assessment that culminates in recommendation that there are sufficient criteria to warrant haemodynamic intervention prior to pregnancy. In the author’s institution, a recovery period of 6 months post-operatively is recommended before then attempting to conceive.

In general stenotic lesions are less well tolerated than regurgitant lesions. Doppler flow velocity, hence calculated pressure gradient across the stenotic RVOT, will increase to double, or even triple baseline during pregnancy as the circulating volume increases. Moderate stenosis before pregnancy is very likely to become severe with pregnancy judged by pressure gradient on Doppler. Although patients with mild to moderate right ventricular outflow tract obstruction may go through pregnancy without major cardiovascular or obstetric complications, relief of right ventricular outflow tract obstruction is indicated by a peak-to-peak gradient of more than 50 mmHg or a peak-right ventricular pressure more than 75 mmHg and should be performed prior to pregnancy. If pregnancy is already embarked on and right ventricular function remains preserved, even severe right ventricular outflow tract obstruction may be tolerated [8], but it may also be complicated by right heart failure and the onset of atrial arrhythmia. If early right heart failure is precipitated by pregnancy, balloon valvuloplasty may need to be considered as part of maternal care.

Aortic dilatation is prevalent in tetralogy of Fallot [9]. For those patients with Caesarean section or more marked aortic dilatation, for example, with aortic dilatation exceeding 50 mm, early epidural and assisted delivery may be advisable. Current guidelines do not suggest intervention for aortic dilatation in the setting or repaired tetralogy of Fallot below diameters of 55 mm [10]. Though aortopathy could potentially complicate pregnancy management in repaired tetralogy of Fallot, acute aortic dissection in the setting of repaired tetralogy of Fallot is extremely rare. To date aortic dissection has only been described in four men all with significantly dilated aortas greater than or equal to 55 mm.

Left ventricular dysfunction as for all patients considering pregnancy confers additional risk. During pregnancy, mild LV dilatation and reduced ejection fraction is a common finding for repaired congenital heart disease including repaired tetralogy of Fallot. Pulmonary hypertension also confers additional risk. This can be secondary to historic use of Waterston surgical shunt though this will become increasingly rare in women with repaired tetralogy of Fallot of childbearing age; it may rarely occur due to small pulmonary arteries in repaired tetralogy of Fallot. Women with the native diagnosis for pulmonary atresia with ventricular septal defect who had pulmonary blood supply via aortopulmonary collateral arteries are discussed below.

For patients with co-morbidity due to coronary artery disease, obesity or diabetes or for those requiring anticoagulation, specific recommendations for these should be followed.

Clinical presentation with pregnancy and unrepaired tetralogy of Fallot is rare but described [11]. Patients may present to specialist adult congenital heart disease services already pregnant with less favourable haemodynamics. Late repair in adulthood of tetralogy of Fallot prior to embarking on pregnancy is preferable.

Most pregnancy outcome studies are small or single centre or retrospective. However, such data as exist suggest that for tetralogy of Fallot patients, most can have successful uneventful pregnancies, but maternal cardiac complications occur in 7–10 % [12], most commonly atrial arrhythmia (6–7 %) [12] and symptomatic right heart failure (2–5 %) [12]. Adverse maternal cardiac events are associated with severe pulmonary regurgitation combined with right ventricular dysfunction, particularly when these occur in combination with left ventricular dysfunction or pulmonary hypertension [10]. In a study of pregnancy in women with repaired tetralogy of Fallot which included 123 completed pregnancies in two centres, the use of cardiac medications prior to pregnancy was the most important predictor of both maternal cardiac events and of small-for-gestational-age babies [13].

Atrial arrhythmia is the most common pregnancy-related cardiac event in patients with repaired tetralogy of Fallot [12, 14]. This is due to the increased circulating volume, which exacerbates the risk of arrhythmia related to scarring caused by atriotomy at previous reparative surgery and by worsening existing chamber dilatation and right ventricular dysfunction. Not surprisingly, a history of arrhythmia increases the chance of recurrence [12, 15, 16].

Ventricular function and cyanosis during pregnancy are the major determinants of outcome for patients with Fallot and pulmonary atresia [16], and careful surveillance of both throughout pregnancy is needed. For the mother, cyanosis may progressively worsen in pregnancy with increasing right to left shunting further reducing pulmonary blood flow and oxygenation. Furthermore, maternal complications related to cyanosis include thrombosis, bleeding diathesis, arrhythmia and heart failure [17]. The risks of fetal complications are high and include fetal loss, low birth weight and prematurity. For sicker patients, bed rest, oxygen therapy and low molecular weight heparin may be required to address maternal oxygen consumption and prevent thromboembolic complications.