Evolution of numbers of adults with unrepaired cyanotic heart defects stratified for age 18–40 years and >40 years followed at the Toronto Congenital Cardiac Centre for Adults between 1980 and 2009 (Modified from Ref.  with permission)
16.1.1 Types of Defects and Pathophysiology of Cyanotic Heart Disease
Cyanotic congenital heart defects that may be encountered in women of childbearing age are summarised in Table 16.1. In this chapter, specific problems pertinent to all congenital cardiac conditions with cyanosis are discussed, but the focus will be on women with unrepaired cyanotic defects with obligatory right-to-left shunting (see Table 16.1 group 1 and Fig. 16.2). More detailed discussion of other lesions potentially associated with cyanosis is found in other chapters (Chaps. 14, 15 and 17).
Types of cyanotic congenital heart defects in adults
Group 1: unrepaired cyanotic defects with obligatory right-to-left shunting
Pulmonary atresia with multicentric pulmonary perfusion
Unrepaired tetralogy of Fallot (in rare cases with only mild right ventricular outflow tract obstruction at rest, the patient may not be cyanotic at rest)
Single ventricle physiology with obstructed pulmonary blood flow
Cyanotic defects after palliative shunt operations without intracardiac repair
Group 2: shunt lesions with resulting irreversible pulmonary hypertension
Eisenmenger syndrome caused by pre-tricuspid shunt lesions (e.g. atrial septal defects)
Eisenmenger syndrome caused by post-tricuspid shunt lesions (e.g. ventricular septal defects)
Eisenmenger syndrome caused by complex congenital heart defects (e.g. single ventricle physiology with unobstructed lung perfusion)
Group 3: congenital cardiac lesions with facultative right-to-left shunting
Ebstein anomaly with interatrial communication
Congenitally corrected transposition of the great arteries associated with ventricular septal defect and pulmonary stenosis (the degree of pulmonary stenosis determines shunt direction)
Group 4: repaired defects with residual lesions leading to right-to-left shunting
Fontan palliation for single ventricle physiology and residual fenestrations or veno-venous collaterals
Patients after atrial switch repair for transposition of the great arteries and residual baffle leaks
Lesions associated with right ventricular diastolic dysfunction (restrictive right ventricular physiology) and residual interatrial shunts
Unrepaired cyanotic defects with obligatory right-to-left shunting (Copyright © 2014 New Media Center, University of Basel. All Rights Reserved). (a) Pulmonary atresia with multicentric pulmonary perfusion. (b) Unrepaired tetralogy of Fallot. (c) Tricuspid atresia with atrial septal defect. (d) Tetralogy of Fallot, palliated with right-sided modified Blalock-Taussig shunt
16.1.2 General Aspects and Pathophysiology of Cyanotic Congenital Heart Defects
All cyanotic congenital cardiac defects have in common that deoxygenated systemic venous blood returning to the heart mixes with oxygenated pulmonary venous blood before being ejected into the systemic circulation. Cyanosis is a manifestation of arterial hypoxemia, which can be estimated by transcutaneous oxygen saturation (SpO2). The degree of hypoxemia depends on the magnitude of right-to-left shunting, which is determined by the size of the shunt lesion (i.e. restrictive or non-restrictive ventricular septal defect), the amount of pulmonary blood flow and cardiac output. While the size of the shunt lesion is typically fixed, cardiac output and pulmonary blood flow are variable and depend on heart rate, stroke volumes of the ventricles and the ratio of vascular resistance between systemic and pulmonary circulations.
16.2 Pregnancy Outcomes
Risk assessment in women with cyanotic heart defects is a multidisciplinary and multistep endeavour that has to take into account all cardiac and noncardiac aspects impacting the individual . Given the decreasing number of women with unrepaired cyanotic heart defects in childbearing age, this patient group is underrepresented in studies that investigated the outcome of women with congenital heart disease in pregnancy [6–8]. Apart from case reports, only few studies have systematically addressed pregnancy outcomes in women with cyanotic heart defects. The largest study, published in 1994, reported the outcome of 96 pregnancies in 44 women with cyanotic heart defects identified from two European centres .
16.2.1 Maternal Outcome
The risk of cardiovascular complications during pregnancy in women with cyanotic congenital heart defects is high, affecting about one third of such women [9, 10]. The most common complication is heart failure, affecting 18.9 % of pregnancies, as reported in the meta-analysis by Drenthen et al. . Other common complications are arrhythmias (4.8 %), endocarditis (4.1 %) and thromboembolic complications (3.6 %). In contrast to cardiovascular complications, obstetric complications seem not to be particularly increased, apart from postpartum haemorrhage, which may be related to coagulation abnormalities and thrombocytopenia, frequently observed in patients with long-standing cyanosis. Nonetheless, the occurrence of obstetric complications, such as hypertensive disorders of pregnancy, pre-eclampsia or multiple pregnancies, increases the haemodynamic load of pregnancy and thus increases the risk of maladaptation and subsequently increases the risk of cardiovascular complications in vulnerable patients [6, 7, 11, 12]. The increased risk of multiple pregnancies may be of particular importance in women seeking assisted fertilisation and underscores the need for optimal multidisciplinary pre-pregnancy communication, counselling and planning.
The occurrence of cardiovascular complications, such as tachyarrhythmias during pregnancy and peripartum may further impair the adaptive capacity of the cardiovascular system and precipitate decompensation. The impact of pregnancy on long-term outcomes in women with cyanotic heart defects is not well defined. Pregnancy may, however, lead to worsening of functional capacity .
16.2.2 Fetal Outcomes
Based on data from lesion-specific outcome series and multicentre studies, the risk of adverse fetal events is extremely high in women with unrepaired cyanotic defects [6, 7, 9]. About half of pregnancies end in spontaneous abortion . In on-going pregnancies beyond 20 weeks of gestation the risk of premature delivery is more than 40 % and two thirds of babies are born small for gestational age . Prematurity can result from spontaneous premature labour but also from early, induced delivery for maternal (cardiac) reasons. For women with cyanotic congenital heart defects, the risk of having a stillbirth is among the highest in all congenital cardiac defects. The high rate of offspring outcomes is illustrated in Fig. 16.3a, adapted from the study of Presbitero et al. . As illustrated in Fig. 16.3b, the risk of fetal complications is strongly predicted by the severity of cyanosis. The fact that women with resting oxygen saturations below 85 % have a very low chance of delivering a viable offspring may have an important bearing on pregnancy counselling and pre-pregnancy optimisation of the underlying cardiac condition.
Fetal outcomes. (Panel a) Proportion of live births, spontaneous abortion and stillbirths among 96 pregnancies. (Panel b) Proportion of live births in relation to resting oxygen saturations (Modified from Ref. )
Apart from the maternal cardiac condition, the risk for offspring events is also determined by obstetric risk factors, such as maternal age, multiple gestations, history of premature delivery or rupture of membranes, incompetent cervix or antepartum bleeding and placental abnormalities . This underscores the need for a multidisciplinary team approach not only during pregnancy but for pre-pregnancy risk assessment and counselling as well.
The recurrence risk of isolated congenital heart defects in the offspring ranges on average between 3 and 5 % . There is however substantial variability in recurrence risk, depending on familial occurrence and type of defect [15, 16]. Some congenital heart defects that may be encountered in women with unrepaired cyanotic defects (i.e. pulmonary atresia or tetralogy of Fallot) are associated with the 22q11 microdeletion syndrome. The inheritance of the 22q11 microdeletion syndrome is autosomal dominant, and recurrence risk is thus 50 %, with a high risk of congenital cardiac defects (particularly conotruncal defects) in the affected offspring.
16.3 Management of Pregnancy
Pregnancies in women with cyanotic congenital heart defects are considered high-risk pregnancies and thus should be managed by a dedicated experienced multidisciplinary team at a tertiary care centre. For each pregnancy, a clear management and follow-up plan must be developed. The frequency of cardiologic and obstetric follow-up visits during pregnancy must be individualised, but most women require close follow-up including frequent assessment of adequate fetal growth. Fetal outcome is associated with uteroplacental blood flow characteristics, and recent evidence suggests that uteroplacental blood flow is associated with maternal haemodynamics in women with congenital heart disease . The impact of changes in uteroplacental blood flow on management decisions needs to be further investigated but may provide an elegant option for additional monitoring maternal haemodynamics . In addition, all pregnant women with CHD should be offered fetal echocardiography between 18 and 21 weeks of gestation.
Assessment at the time of cardiology visits usually includes thorough clinical examination with serial measurements of resting oxygen saturations, blood work to ensure adequate secondary erythrocytosis and adequate iron stores, as well as transthoracic echocardiography at least at baseline and between 28 and 30 weeks of gestation at the haemodynamic peak of pregnancy. Depending on the clinical course, symptoms and findings on clinical examination, echocardiography may be needed more often.
The importance of patient education at each clinic visit cannot be overemphasised. Every woman who experiences novel or worsening symptoms during pregnancy (i.e. palpitations or increasing shortness of breath) should be encouraged to seek prompt assessment by her specialised multidisciplinary team.
As women with unrepaired cyanotic heart defects have a high risk of paradoxical systemic embolism, meticulous thromboembolic prophylaxis is mandatory at times of increased risk, particularly in women requiring bed rest.
16.3.1 Management of Heart Failure in Pregnancy and Peripartum
Women with unrepaired cyanotic heart defects may be prone to develop heart failure, as many have diastolic ventricular dysfunction and may not tolerate the increasing volume load of pregnancy. Serial measurements of natriuretic peptides (Pro-BNP or BNP) may help in diagnosis and risk stratification of heart failure during pregnancy [19, 20].
In women with unrepaired cyanotic heart defects, heart failure may present with worsening cyanosis, as shifts in the balance between systemic and pulmonary vascular resistance may precipitate increased right-to-left shunting. For these women, the mainstay of therapy is bed rest to reduce further exacerbation of cyanosis triggered by physical activity.
If overt heart failure occurs, patients should be admitted to a specialised centre, and precipitating factors, such as infection or arrhythmias, should be actively sought and excluded. Bed rest, supplemental oxygen and careful fluid balance with daily weight measurements should be initiated. Careful administration of diuretics may be used but with caution to avoid overdiuresis which can reduce uteroplacental blood flow.
In the case of refractory heart failure, delivery should be contemplated as soon as the fetus is viable, or, in the case of persistent haemodynamic instability, irrespective of the duration of gestation. Antenatal steroids to improve fetal lung maturity may lead to maternal fluid retention and worsening of heart failure.
16.3.2 Multidisciplinary Delivery Plan
There are no data on whether vaginal delivery or Caesarean section is superior in women with cyanotic heart defects. Depending on the type of defect, myocardial function and residual haemodynamic lesions, women with cyanotic heart defects may have limited cardiovascular reserves to cope with the haemodynamic needs of labour and delivery. Effective analgesia and assisted second stage of delivery can effectively decrease the additional haemodynamic load of labour. Assisted delivery may however be associated with a higher risk of postpartum haemorrhage and high-degree lacerations . The average blood loss during vaginal delivery of 500 ml counteracts the impact of autotransfusion from the contracting uterus at stage 3 of delivery. Blood loss with Caesarean section is usually higher (on average 1,000 ml) which may be a disadvantage in women for whom (relative) anaemia may be deleterious.
A multidisciplinary delivery plan, based on local experience, logistics and infrastructure (e.g. possibilities for monitoring on labour ward), should be developed early in all women with cyanotic heart defects. Given the high rate of premature delivery, this detailed delivery plan must be available and easily accessible as soon as the fetus is viable. Early involvement of experienced obstetric anaesthetists and, if required, the input of cardiac anaesthetists are vital. Important aspects that need to be covered by the delivery plan are summarised in Table 16.2. A schematic drawing of the patient’s cardiac anatomy is always helpful and may be of critical importance if emergency central venous line or temporary pacemaker insertion is required in women with unusual systemic venous anatomy. It is wise to ensure that air bubble filters are easily available on the labour ward.
Requirements for a comprehensive multidisciplinary delivery plan
Content of a comprehensive multidisciplinary delivery plan
1. Information on the underlying heart defect and current haemodynamics
☑ Exact cardiac diagnosis, previous surgical and interventional procedures
☑ Schematic drawing of the woman’s heart is mandatory as most have complex anatomyPremium Wordpress Themes by UFO Themes
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