Right heart lesions usually lead to abnormal loading conditions of the right ventricle and can generally be divided into those in which the ventricle is predomi- nantly subjected to volume or pressure overload.
Volume overload to the right ventricle results from lesions in which the pulmonary or tricuspid valve is regurgitant or in which additional volume is deliv- ered to the right heart and the pulmonary circulation because of left -to-right shunting (more at the atrial than the ventricular level). Volume overload is typi- cally increased in lesions such as:
• atrial septal defect (ASD)
• pulmonary regurgitation (isolated [rare] or resulting from repair of tetralogy of Fallot (ToF) or relief of pulmonary valve stenosis)
• Ebstein anomaly of the tricuspid valve .
Pressure overload to the right ventricle results from lesions such as:
• pulmonary stenosis (isolated or associated with ToF)
• ccTGA
• TGA aft er Mustard or Senning repair.
Th e latter two lesions have the right ventricle support- ing the systemic circulation. Th ey thus represent an extreme form of right ventricular pressure overload .
In addition, “univentricular” hearts palliated with a Fontan-type operation can be considered right heart lesions because there is no substantial ventricle to sup- port the pulmonary circulation, although the right heart may not be anatomically involved from the out- set. Th us, this group of women will also be discussed in this chapter .
Furthermore, chronic cyanosis (without pulmo- nary arterial hypertension) is oft en a feature of right heart lesions such as pulmonary atresia with ventricu- lar septal defect (VSD) and multiple aortopulmonary collateral arteries (MAPCA). Th is lesion will also be discussed in this chapter to highlight some general concepts of care for women with cyanotic heart disease without pulmonary arterial hypertension.
Atrial septal defect
ASDs account for about 7–10% of cases of CHD, and are two to three times more common in women than men.[ 13 ] Various forms of ASD exist with respect to their anatomical position in the interatrial septum ( Figure 14.1 ). Th e defect may be located in the region of the oval fossa (forming the ostium secundum ASD)
or in the lower part of the interatrial septum (form- ing the ostium primum ASD). Th e sinus venosus ASD is located in the cranial part of the interatrial septum, with the superior vena cava overriding the defect or, in rare cases, in the caudal part of the inter- atrial septum. Th e ostium secundum ASD is by far the most common type and can oft en be closed with a transcatheter-delivered device, whereas surgical clo- sure is needed for the other types of ASD. An ostium primum ASD is oft en associated with regurgitation of the left -sided atrioventricular valve .
Regardless of the anatomical position, any ASD per- mits blood fl ow from the left to the right atrium, which leads to enlargement of the right atrium and ventricle and increased pulmonary blood fl ow ( Figure 14.2 ).
Indications for ASD closure mostly depend on the size of the defect and the degree of right heart volume overload. A small defect without any evidence of right atrial or right ventricular enlargement does not warrant closure (unless there is previous history of paradoxical embolism with transient ischemic attack or stroke).
An ASD leading to right heart enlargement (the ratio of pulmonary to systemic blood fl ow is usually >1.5) should ideally be closed before pregnancy. Pulmonary hypertension (PH) is not common in patients with ASD but has to be excluded before closure. Anticipated benefi ts of ASD closure are improved functional class and overall quality of life, as well as risk reduction for atrial arrhythmia and right heart failure .[ 14 – 17 ]
In the absence of PH and right ventricular dys- function, pregnancy is well tolerated in a woman with an ASD, regardless of whether it is repaired or unre- paired.[ 18 ]
Superior sinus venous defect
Superior caval vein
Oval fossa defect
‘Primum’ defect
Tricuspid valve Floor of oval
fossa
Inferior sinus venosus defect
Coronary sinus defect
Inferior caval vein
Figure 14.1 Anatomy of the most common types of atrial septal defect, viewed from the right atrium. RA = right atrium; RV = right ventricle.
Reproduced with permission from Gatzoulis et al .[ 51 ]
Section 4: Antenatal Care: Specifi c Maternal Conditions
In patients with an unrepaired ASD, the pregnancy-related decrease in systemic vascular resist- ance reduces the magnitude of left -to-right shunting.
Consequently, the eff ects of increased cardiac output and blood volume on the right ventricle are attenuated . Atrial arrhythmias (from right atrial distension) and paradoxical embolism are potential hazards during pregnancy, although the latter is uncommon. A prepreg- nancy history of arrhythmia and maternal age older than 30 years are risk factors for maternal cardiac com- plications.[ 18 ] Low-dose aspirin can be considered to reduce the risk of thromboembolic events, and throm- boprophylaxis with low-molecular-weight heparin (LMWH) should be commenced if bed rest is required.
Furthermore, prevention of venous stasis (use of com- pression stockings and avoiding the supine position) and use of an air-fi lter or avoidance of air in intravenous lines is important to prevent systemic embolization due to potential right-to-left shunting during labor.[ 7 , 19 ]
Women with an unrepaired ASD have a slightly increased risk of preeclampsia, fetal loss, and low birth weight, whereas patients with repaired defects have a risk similar to that of the general population .[ 18 ]
Tetralogy of Fallot
ToF is the most common cyanotic congenital heart lesion and constitutes about 5–10% of cases of CHD.
[ 20 , 21 ] ToF consists of a large VSD, right ventricular outfl ow tract obstruction, right ventricular hypertro- phy, and overriding of the aorta ( Figure 14.3 ).
Surgical repair includes VSD closure and relief of the right ventricular outfl ow tract obstruction. In cases with a small pulmonary valve annulus, the out- fl ow tract obstruction can be relieved by a transan- nular patch, leading to free pulmonary regurgitation.
Over time, this massive pulmonary regurgitation may lead to right ventricular enlargement and dysfunction, which is associated with ventricular tachycardia and sudden cardiac death.[ 22 ] Atrial arrhythmias are not uncommon aft er repair of ToF, especially if right atrial enlargement is present.
Nevertheless, pregnancy is a relatively low-risk endeavor for most women with repaired ToF. Th e risks of pregnancy largely depend on the hemodynamic status aft er repair. Mild to moderate right ventricular outfl ow tract obstruction is well tolerated and so is pul- monary regurgitation, provided that right ventricular function is maintained. Severe pulmonary regurgitation aft er ToF repair with right ventricular dilatation has, however, been reported as a maternal risk factor dur- ing pregnancy; pulmonary valve replacement prior to pregnancy has therefore been recommended.[ 23 ] More recent data question this strategy by showing that severe pulmonary regurgitation and right ventricular dilata- tion are well tolerated unless additional risk factors such as twin pregnancy, branch pulmonary stenosis, right ventricular systolic dysfunction, and right ventricu- lar hypertrophy are present.[ 24 ] Furthermore, the risk of adverse maternal events associated with pregnancy increases if there is a history of ablation, cardiovascu- lar medication, right or left ventricular dysfunction, PH due to small pulmonary arteries, or previous central aor- topulmonary shunt procedures.[ 25 – 28 ]
During pregnancy, regular assessment should focus on signs of right and left heart dysfunction and clinical arrhythmia. Maternal cardiovascular events during pregnancy are highly associated with perinatal complications for the fetus.[ 27 ]
Th e long-term impact of pregnancy on right ven- tricular size and function in repaired ToF patients is uncertain. Th ere are some data to indicate that preg- nancy in this patient group may result in persisting medium-term enlargement of the right ventricle, an eff ect that has been observed in nonpregnant ToF con- trol patients .[ 29 ]
ToF can be part of the DiGeorge syndrome (pre- sent in 15% of ToF patients). Genetic testing should be
Figure 14.2 Cardiac magnetic resonance image of an atrial septal defect (ASD; arrow); the ASD results in left-to-right shunting; blood from the pulmonary veins enters the left atrium (LA), after which some of it crosses the ASD into the right atrium (RA), subsequently leading to enlargement of the RA and right ventricle (RV). LV = left ventricle.
Reproduced with permission from Gatzoulis et al .[ 51 ]
off ered before pregnancy because the recurrence risk of DiGeorge syndrome is 50%. In its absence, the risk of recurrence of CHD in the fetus is about 2–3% .[ 30 ]
Small retrospective controlled cohort studies show a mildly higher incidence of antenatal complications such as spontaneous rupture of membranes, gestational hypertension, and antepartum hemorrhage in women with repaired ToF. Neonatal outcomes were similar, despite a signifi cantly lower birth weight: babies of mothers with a repaired ToF were on average about 500 g lighter than those of a healthy control popula- tion.[ 31 ]
Ebstein anomaly of the tricuspid valve
Ebstein anomaly is an apical displacement of the tricuspid valve leading to enlargement of the right atrium and, oft en, tricuspid regurgitation. Th e anom- aly is frequently associated with an ASD that allows right to left shunting and cyanosis, as well as with Wolff –Parkinson–White syndrome in about 15%
of patients. Survival into adulthood is common in mild to moderate cases, but patients can present with right heart failure, supraventricular arrhythmias, or cyanosis.
Owing to ineffi cient right heart function, patients have reduced cardiac output reserve, which can be further compromised by atrial reentry tachycardia.
Chest radiography to assess heart size prior to concep- tion ( Figure 14.4 ) is an approximate, but reproducible, marker of severity of disease.
In women without cyanosis or signs of heart fail- ure, pregnancy is usually well tolerated. However, Ebstein anomaly is associated with an increased risk of preterm birth and fetal loss, especially in cyanotic women.[ 32 , 33 ] Birth weight is oft en lower, especially in cyanotic women. Monitoring during pregnancy should focus on the potential development of cyano- sis, heart failure, and arrhythmias. If an ASD is present, low-dose aspirin should be considered to reduce the risk of thromboembolic events, and thromboprophy- laxis with LMWH should be commenced if bed rest is required .
Pulmonary stenosis
Pulmonary stenosis is an isolated congenital obstruc- tion of the right ventricular outfl ow tract, usually at the level of the pulmonary valve and occasionally at the sub- or supravalvar level. It accounts for about 10% of cases of CHD. Catheter interventional or sur- gical relief of pulmonary stenosis is recommended for patients with a peak pressure gradient across the steno- sis of >50 mmHg or a peak right ventricular pressure of >75 mmHg. Ideally, it should be performed before pregnancy.[ 34 ]
Adult patients with pulmonary stenosis are mostly asymptomatic, but when the stenosis is severe and
Hypertrophied right ventricle Infundibular stenosis
Overriding aorta
Hypoplastic pulmonary trunk Ventricular septal defect RV LV
RA
Figure 14.3 Tetralogy of Fallot is characterized by a large ventricular septal defect (VSD), an aorta that overrides the left and right ventricles, obstruction of the right ventricular outfl ow tract, and right ventricular hypertrophy; with substantial obstruction of the right ventricular outfl ow tract, blood is shunted through the VSD from right to left.
Reproduced with permission from Uebing et al .[ 52 ]
Figure 14.4 Typical chest X-ray of a moderate Ebstein anomaly of the tricuspid valve; note a large heart with normal and not increased pulmonary vascular markings and a small pedicle of the heart (small pulmonary artery and aorta), indicative of the low cardiac output status.
Section 4: Antenatal Care: Specifi c Maternal Conditions
longstanding they can develop right heart failure or atrial arrhythmia. If interatrial communication is present, right to left shunting may occur and result in cyanosis. Isolated right ventricular outfl ow tract obstruction—even when severe—is usually well tol- erated during pregnancy when right heart function is preserved.[ 35 ] Balloon valvuloplasty should be con- sidered in cases of right heart failure during early preg- nancy (see Chapter 8 ).[ 36 ]
Pulmonary stenosis can be part of Noonan syn- drome (clinical features: short stature, a short webbed neck, pectus excavatum, hypertelorism, and low-set ears). Noonan syndrome is of autosomal dominant inheritance and therefore carries a recurrence risk of 50%. Genetic testing should be off ered before preg- nancy if Noonan syndrome is suspected clinically.
Furthermore, patients with Noonan syndrome have a more myxomatous type of pulmonary stenosis, oft en involving the supravalvar area, and usually do not respond well to balloon valvuloplasty .
Congenitally corrected transposition of the great arteries
In ccTGA, the ventricles and great arteries are
“inverted.” Systemic venous return enters the left ven- tricle, which then ejects into the pulmonary artery.
Pulmonary venous return enters the right ventricle, which fi lls the aorta. Th e circulation is therefore “phys- iologically corrected” but the right ventricle supports the systemic circulation ( Figure 14.5 ).
ccTGA is oft en associated with the following heart defects, which have an impact on prognosis:
• systemic (tricuspid) atrioventricular valve abnormalities (Ebstein-like) with valve insuffi ciency
• VSD
• subpulmonary stenosis
• complete heart block (acquired)
• Wolff –Parkinson–White syndrome .
Successful pregnancy can be achieved by many women with ccTGA and a systemic right ventricle. Th e over- all risk for this group depends largely on associated lesions, systemic ventricular function, function of the systemic atrioventricular valve (tricuspid valve), and the woman’s functional class.[ 37 , 38 ] While the long- term impact of successful and completed pregnancy on right ventricular function in women with ccTGA is somewhat unclear, a mortality rate of up to 4% and an increased risk of fetal loss has been reported in a small series of women with systemic right ventricles, and this needs to be discussed in preconception coun- seling.[ 8 , 39 – 41 ]
CMR imaging should be performed as part of the prepregnancy evaluation because it provides invalu- able data on the function of the systemic right ventri- cle and the function of the tricuspid valve. A treadmill exercise before pregnancy will document the woman’s functional status and her ability to increase heart rate during exercise. Monitoring during pregnancy should include serial assessment of ventricular and
A P
LA RA
RV
LV
Normal Congenitally corrected
transposition
A P
LA RA
RV LV
Figure 14.5 The ventricles are inverted in congenitally corrected transposition of the great arteries; systemic venous return enters the left ventricle (LV), which ejects into the pulmonary circulation (P);
pulmonary venous return enters the right ventricle (RV), which supports the systemic circulation. A = aorta, RA = right atrium, LA = left atrium.
Reproduced with permission from Uebing et al .[ 52 ]
tricuspid valve function, as well as of the heart rhythm.
Ventricular and valve function may deteriorate when blood volume and cardiac output increase during pregnancy .
Transposition of the great arteries
TGA accounts for 5–7% of all congenital heart malfor- mations. In TGA, the right ventricle gives rise to the aorta and the left ventricle gives rise to the pulmonary artery ( Figure 14.6 ). Th e majority of adults with this condition will have had an “atrial switch operation”
(Mustard or Senning operation) in childhood, in which the systemic venous return was directed to the subpulmonary left and the pulmonary venous return was directed to the systemic right ventricle using baf- fl es. Aft er an atrial switch operation, patients have the right ventricle supporting the systemic circulation, as in ccTGA.
Late complications following the atrial switch operation include baffl e leak or stenosis, sinus node dysfunction with bradycardia, atrial arrhythmias, and dysfunction of the systemic right ventricle with sec- ondary tricuspid regurgitation. Women with good or only mildly impaired right ventricular function and no history of arrhythmia have a relatively low risk during pregnancy .[ 42 , 43 ]
Prepregnancy evaluation should include a thor- ough assessment of ventricular function. Patency of the atrial baffl es should also be evaluated before preg- nancy to ensure that an increased cardiac output can be accommodated ( Figure 14.7 ). Both ventricular
function and patency of the baffl es are ideally assessed with cardiovascular magnetic resonance imaging.
As tachycardia is part of the physiological adapta- tion of the circulatory system to pregnancy, exercise testing may provide valuable information on chrono- tropic competence before pregnancy .
During pregnancy, clinical assessment should focus on the early signs of heart failure and arrhyth- mias. If atrial tachycardia occurs, sinus rhythm should be restored without delay. Direct current cardioversion
Figure 14.6 Transposition of the great arteries (TGA) and atrial switch operation;
in TGA (complete transposition), systemic venous blood returns to the right atrium (RA), from which it goes to the right ventricle (RV) and then to the aorta (A); pulmonary venous blood returns to the left atrium (LA), from which it goes to the left ventricle (LV) and then to the pulmonary artery (P).
Reproduced with permission from Uebing et al .[ 52 ]
Figure 14.7 Cardiac magnetic resonance imaging of a patient with transposition of the great arteries and atrial switch operation;
a baffl e (small arrows) is created in the atria to redirect blood from the left atrium (LA) into the systemic right ventricle (RV); systemic venous blood returns to the subpulmonary left ventricle (LV); the systemic RV is markedly enlarged, squashing the LV.
Reproduced with the kind permission of Dr Philip Kilner, CMR Unit, Royal Brompton & Harefi eld NHS Trust, London, UK
RV RV
RA RA
LA LA
P P
A A
LV LV
Normal Complete
transposition
Section 4: Antenatal Care: Specifi c Maternal Conditions
is usually eff ective and safe when needed during pregnancy .
Th ere is an increased risk of thromboembolic events during pregnancy in women who have undergone the atrial switch procedure, mainly as a consequence of atrial tachycardia and/or systemic ventricular dysfunc- tion. As a consequence, anticoagulation with warfarin/
LMWH should be considered when atrial tachyar- rhythmia is present .[ 19 ]
Early evidence suggests that pregnancy may have an adverse long-term eff ect on ventricular function and on the functional class of women with TGA and previous atrial procedures; this needs to be investi- gated further.[ 39 , 44 ]
Univentricular hearts after Fontan-type operations
Many adults with functional “univentricular hearts”
have undergone Fontan-type operations. Following the Fontan operation, the systemic venous return is diverted directly to the pulmonary circulation without incorporation of a subpulmonary ventricle. Blood fl ow to the lungs is driven mainly by systemic venous pres- sure and respiration. Th e “single” ventricle can be of right- or left -sided morphology and supports the sys- temic circulation ( Figure 14.8 ).
Several Fontan-type operations exist; they connect either the right atrium or the caval veins with the pul- monary arteries. Th e latter is called total cavopulmo- nary connection ( Figure 14.9 ).
All “Fontan patients” are at risk of various compli- cations related to surgery and/or abnormal circulatory physiology that persists aft er surgery (“low cardiac output status”):
1. Atrial arrhythmias related to scarring from surgery or to atrial distension from high venous pressure are common and can cause profound hemodynamic deterioration.
2. Th rombotic diathesis is present as a consequence of sluggish blood fl ow in the systemic venous pathways and/or in the right atrium.
3. Impairment of ventricular function is part of the “natural” history in these patients, especially if the systemic ventricle has right ventricular morphology.
4. Cyanosis can result from persistent systemic venous to left -sided bypass tracts, leading to right to left shunting .
Although data are limited, it can be assumed that the overall risk of maternal complications for women with single ventricle physiology palliated with a Fontan-type procedure is moderate, but there is a high risk of miscarriage.[ 45 ] Legitimate concerns mainly relate to the eff ect of pregnancy on ventricular func- tion, a prothrombotic circulatory system, and a ten- dency to poorly tolerated atrial arrhythmias.
Th e risks of pregnancy mainly relate to the wom- an’s functional status, her history of arrhythmias, her ventricular function, and the degree of cyanosis.[ 45 ] Th e maternal risk is lower if the woman is in NYHA
RV SV
Normal Single ventricle
RA RA
LV
LA LA
PA PA
AO AO
Figure 14.8 As opposed to in the normal heart, a “single” ventricle (SV) collects blood from the right atrium (RA) and the left atrium (LA). PA = pulmonary artery; AO = aorta; RV = right ventricle;
LV = left ventricle.
Reproduced with permission from Uebing et al .[ 52 ]