Valvar heart disease, both acquired and congenital, is the most common indication for cardiac intervention during pregnancy. General issues in valvar heart dis- ease in pregnancy are dealt with in Chapters 11 and 13 , and in extensive recent reviews.[ 29 , 49 – 51 ] Th is dis- cussion will focus on the indications for, and the man- agement of, cardiac intervention for valvar lesions in pregnant women.
Mitral valve stenosis
Th e greatest number of cardiac interventions in preg- nancy involve mitral stenosis. Most experience has been in developing countries with higher incidences of rheumatic heart disease.[ 3 ] Worldwide, mitral steno- sis is the most common symptomatic valvar abnormal- ity seen in pregnancy.[ 29 ] Th e pregnancy-associated rise in circulating volume and HR results in a corre- sponding increase in the pressure gradient across the narrowed mitral valve, which can result in heart fail- ure and pulmonary edema. Additionally, the rise in atrial pressure may give rise to atrial arrhythmias, with increased HR and/or loss of atrial contraction further exacerbating the unfavorable hemodynamics and worsening the heart failure. Recent reports confi rm the high incidence (65%) of arrhythmias and heart failure in pregnant women with severe mitral stenosis, as well as an increased risk of fetal mortality and morbidity.
[ 3 , 51 , 52 ] Despite these high rates of maternal compli- cations with severe mitral stenosis, no maternal deaths were reported in these series. However, fetal morbidity was related to the severity of the mitral stenosis, with a 33–44% rate of preterm delivery and a 33% incidence of fetal growth restriction .
Women with severe mitral stenosis who wish to become pregnant need to be counseled about the risks of the pregnancy to them and to the child, and should be off ered therapeutic choices. PBMV prior to pregnancy has been successfully used to minimize pregnancy-associated clinical deterioration in such women and reduce the requirement for medication (with its attendant fetal risks) or cardiac intervention
Section 2: Antenatal Care: General Considerations
during the pregnancy.[ 29 ] If the presence of severe cal- cifi cation or associated mitral regurgitation make the woman an unsuitable candidate for PBMV, then mitral valve replacement can be considered. Despite the maternal and fetal risks in pregnant women who have had mitral valve replacement prior to pregnancy,[ 49 ] the series by Bhatla et al. demonstrated that only 3% of those who had had valve replacement surgery deterio- rated into New York Heart Association (NYHA) func- tional class III–IV compared with 26% of those who had had either valvotomy or no prior intervention.[ 3 ] Furthermore, there were fewer fetal growth-restricted and low-birthweight infants born to mothers with prosthetic valves. However, such an approach does raise the issue of whether tissue valves (needing a fur- ther replacement in 10–15 years) or metal valves (rais- ing problems of anticoagulation in pregnancy) should be used (see Chapter 11 ).
Th e surgical approach to mitral stenosis in devel- oped countries focuses on open mitral valvuloplasty and mitral valve replacement, both of which require the use of cardiopulmonary bypass with its attendant risks to the fetus (see above). De Souza et al. reported on 24 pregnant women who underwent open mitral valvuloplasty for refractory severe heart failure due to mitral stenosis.[ 53 ] Th ere was only one maternal death but six fetal and two neonatal deaths. In another report of 73 women undergoing mitral valve replacement or open mitral valvuloplasty, there was 1 maternal death and 10 fetal deaths .[ 8 ]
Closed mitral valvotomy surgery has been per- formed for more than six decades and is oft en the pre- ferred approach to severe mitral stenosis for patients in developing countries. Because there is no need for cardiopulmonary bypass, closed mitral valvotomy may have some advantages in pregnant women. Audits of closed mitral valvotomy in pregnancy in developing countries have reported no maternal mortality and fetal mortality rates of 0–12%.[ 28 , 54 ] However, there is a signifi cant likelihood of re-stenosis and a need for repeat surgery. Furthermore, the closed procedure can be used only for isolated mitral stenosis, with no left atrial thrombus, no heavy calcifi cation, and a reason- ably well-preserved valvar/subvalvar apparatus. In developed countries, closed mitral valvotomy has been abandoned in favor of open mitral commissurotomy and mitral valve replacement because of better hemo- dynamic and long-term results with these procedures.
Th erefore, in these countries, cardiac surgeons are no longer being trained in the technique of closed mitral
valvotomy and it cannot be considered a realistic option in that context .
PBMV has been practiced for more than 20 years with excellent results. In a series of 2773 nonpregnant patients, there was a technical failure rate of 1.2% and an in-hospital death rate of 0.4%. Good results (mitral valve area >1.5 cm 2 and no regurgitation more than grade 2 out of 4) were obtained in 90% of patients, with only 4.7% having to undergo mitral surgery within the fi rst month aft er the percutaneous procedure.[ 55 ] Increasingly, PBMV is being used in pregnancy for women in NYHA functional class III–IV refractory to medical therapy and the experience of its use in preg- nancy has been equally positive. Th e technique using the Inoue balloon has been well described.[ 56 ] Th ere has now been extensive experience of the use of PBMV to treat medically refractory symptomatic mitral ste- nosis in pregnancy.[ 4 , 31 , 53 , 57 ] Symptomatic, hemo- dynamic, and echocardiographic improvement is seen in the vast majority of treated women. Th e excellent results achieved are probably related to the underlying valvar pathology. Th e valves in these young mothers are unlikely to be heavily calcifi ed or to have signifi cant subvalvar thickening. Commissural fusion is the major pathology, and this makes them good candidates for PBMV. Maternal mortality has been very low (<0.3%), as has fetal/neonatal mortality (0–5%). [ 31 , 57 ]
Balloon infl ation has been reported to cause a tran- sient decrease in maternal blood pressure and fetal HR, with a return to baseline levels within a few seconds of balloon defl ation.[ 57 ] Th e woman is recumbent for the procedure and pressure from the uterus may result in maternal hypotension and hinder the passage of catheters.[ 48 ] Th e rate of reported complications has been low but maternal complications do include car- diac tamponade, residual atrial septal defect, excessive blood loss, venous thrombosis, transient atrial fi bril- lation, deterioration in degree of mitral regurgitation, and systemic embolization. Furthermore, PBMV has precipitated uterine contractions and resulted in pre- term labor.[ 29 , 58 ] Tocolytics have been used to sup- press labor precipitated by the procedure but tocolytic agents may have signifi cant cardiovascular eff ects and must be used with caution .[ 18 ]
Th e other concern remains the radiation risk.
In some centers, therapeutic terminations of preg- nancy have been off ered to women who had PBMV before 18 weeks of gestation. However, early follow-up reports of children born aft er the procedure found no evidence of abnormal growth or development,
although these studies included follow-up of <8 years.
[ 31 , 59 ] Mishra et al. reviewed fl uoroscopy exposure times from several series and reported that 95% of the procedures had <16 min of fl uoroscopy time and that the average fl uoroscopy time for their own group of 85 women was 3.6±3.2 min.[ 4 ] Such exposure times would not be expected to materially aff ect fetal risk.
Even so, all measures should be taken to limit radia- tion risks to the fetus, including use of the Inoue bal- loon, which requires less procedural time,[ 29 , 60 ] and increased use of transesophageal echocardiography to reduce fl uoroscopy time.[ 39 , 40 , 59 ] Because of the increased sensitivity to radiation eff ects in early preg- nancy, PBMV should be avoided in the fi rst trimester if possible. Fortunately, the hemodynamic changes of pregnancy are such that most women with mitral ste- nosis do not deteriorate clinically until the second or third trimester .
PBMV by the Inoue balloon technique is prob- ably the ideal treatment for signifi cant symptomatic mitral stenosis in pregnant women.[ 60 ] Although, to date, there have been no direct comparative studies of PBMV and mitral valve surgery in pregnancy (and such a future study is unlikely), cumulative descriptive reports have shown lower maternal and fetal/neonatal mortality rates and an acceptable rate of complica- tions with the percutaneous approach.[ 4 , 31 , 53 , 57 , 59 ] However, there are the unknown risks of future prob- lems from radiation exposure, and the risks of pre- cipitating premature labor. Th erefore, this procedure must be limited to those symptomatic women for whom medical therapy has not been successful. PBMV is no substitute for expert management during preg- nancy, labor, and delivery. Th e procedure cannot be performed in women with more than moderate mitral regurgitation, left atrial thrombus, marked calcifi ca- tion, or absence of commissural fusion. If such women with severe mitral stenosis cannot be controlled med- ically,[ 51 ] they will need careful assessment for mitral valve surgery, keeping in mind the higher fetal loss associated with the cardiopulmonary bypass necessary for such surgery .
Aortic valve stenosis
Severe aortic valve stenosis was traditionally consid- ered a contraindication to pregnancy, with increased maternal mortality and morbidity, as well as con- cerns about clinical deterioration, leading to preterm delivery and fetal morbidity.[ 29 , 52 ] However, recent
reports suggest a more optimistic outcome for this group of women. Of 70 pregnancies with aortic ste- nosis reviewed by Tzemos et al. 71% had moderate or severe aortic stenosis.[ 50 ] Th ere were no cardiac complications in the women with mild aortic stenosis.
Th ere were seven pregnancies (four with severe aortic stenosis and three with moderate aortic stenosis) that were complicated by pulmonary edema (two pregnan- cies), supraventricular tachycardia (one pregnancy), and worsening of NYHA functional class by >2 (four pregnancies). Of the four patients with severe aortic stenosis, two had refractory symptoms and required balloon valvuloplasty. No patient required cardiac sur- gery. Th ere were no maternal deaths and all 70 preg- nancies resulted in live births.
Th is more recent experience exemplifi es the cur- rent management of severe aortic stenosis in pregnant women.[ 50 ] Most reports consider severe aortic sten- osis to be present if the aortic valve area is <1 cm 2 with a peak systolic velocity of 4 m/s or higher.[ 50 ] Attempts should be made to identify preconception those women with severe aortic stenosis and consider valve surgery or balloon valvotomy before pregnancy. Th e choice of valve replacement becomes important because of the increased risks in pregnancy for women with prosthetic valves ( Chapter 11 ). For women with aortic stenosis, an attractive alternative to bioprosthetic or mechanical valves may be the pulmonary autograft (Ross proced- ure).[ 61 ] For women with severe aortic stenosis who present already pregnant, discussion needs to focus on the risks of the pregnancy for mother and child, and include termination, continuing medical manage- ment, and the need for intervention, either surgical or balloon valvuloplasty.[ 29 ] Th ese women should also be advised that even if they deliver successfully without cardiac intervention, there is a signifi cant likelihood of a need for such intervention postpartum.[ 50 ]
Women who develop symptoms may respond to medical therapy that includes bed rest, diuretics, and close monitoring, generally in a hospital environ- ment.[ 29 ] Failure to respond to medical management requires decisions about termination, early delivery, or cardiac intervention . Cardiac intervention must be limited to women with clinical deterioration. A high gradient across the aortic valve during pregnancy is not a suffi cient reason for intervention.[ 39 ] Aortic valve surgery has been successfully carried out in preg- nancy for decades but the number of reported cases has been small. Because of the small numbers, most case series on cardiac surgery in pregnancy have not
Section 2: Antenatal Care: General Considerations
separately reported the mortality or morbidity results for only the women undergoing aortic surgery.[ 2 , 9 , 16 ] Two separate reviews from 1994 and 1996 reported no maternal mortality but fetal losses of 30–38% in two small groups of 18 and 15 women.[ 5 , 23 ] Th ere have been no recent large series of aortic valve replacement in pregnancy, but in 2003 Jahangiri et al. did report replacement of the aortic valve in four women: one with congenital aortic stenosis, two with aortic regur- gitation, and one with mitral and aortic stenosis.[ 22 ] All four women did very well during surgery and three women delivered a normal baby at 38 weeks by cesarean section. Th e fetus in the fourth case showed evidence of hydrops a week aft er surgery and the pregnancy was terminated 2 weeks aft er surgery. Although there have been no large series of pregnant women under- going aortic valve surgery, it is clear that fetal mortal- ity remains a major concern. It is for this reason that balloon aortic valvotomy has been performed in preg- nant women with aortic stenosis refractory to medical therapy. Th ere have been only a few cases of PBAV in pregnancy reported in the literature.[ 39 , 50 , 62 ] In all reported cases, there has been a reduction in valvar gradient and an improvement in the clinical situation, without fetal loss .
Unlike PBMV, PBAV in nonpregnant adults has been considered a palliative procedure because the improvement in hemodynamics has been transient and there has been no demonstrated improvement in long-term survival. Its use has therefore been relegated to the elderly with severe aortic stenosis who are not considered candidates for aortic valve replacement, and it has been used as a “bridge to surgery” for those in cardiogenic shock or for those who require urgent non- cardiac surgery. It cannot be considered an alternative to aortic valve replacement in the adult. Complications of PBAV have included embolic phenomena, marked aortic regurgitation, hemopericardium, and aor- tic rupture but none of these has yet been reported with PBAV during pregnancy.[ 48 , 62 ] It should not be performed in the setting of already signifi cant aortic regurgitation or a heavily calcifi ed valve. It carries the risk of radiation exposure to mother and fetus but the increasing use of transesophageal echocardiography during PBAV does reduce fl uoroscopy times. [ 39 ]
Th ere have been no reported series of PBAV in preg- nancy and certainly no comparative studies with aortic valve surgery. Given the rarity of the need for inter- vention, such future series are unlikely. PBAV must be considered palliative; the woman must understand
that she will require defi nitive aortic valve surgery in the future and that the sole purpose of the PBAV is to allow her pregnancy to continue. Th ere is no role for transcatheter aortic valve replacement in the pregnant patient with aortic stenosis .
Pulmonary valve stenosis
Pulmonary stenosis during pregnancy is most prob- ably due to congenital obstruction at the valvar, sub- valvar, or supravalvar level but has also been described in the setting of stenosis in a homograft that had been part of a previous Ross procedure.[ 29 , 63 ] Unlike with mitral stenosis or aortic stenosis, even severe pulmo- nary stenosis does not appear to have an adverse eff ect on maternal or fetal morbidity and mortality.[ 48 , 64 ] Balloon valvuloplasty for pulmonary stenosis has been performed in nonpregnant patients but only a hand- ful of cases of balloon valvuloplasty during pregnancy have been reported.[ 48 ] Th ese resulted in signifi cant improvements and no complications, but experience is limited and the procedure should be considered only for rare women with severe symptomatic valvar pulmonary valve stenosis that is refractory to medical management .
Mitral or aortic regurgitation
Mitral regurgitation during pregnancy may be due to mitral valve prolapse or rheumatic mitral disease.
It may also occur as a consequence of valvuloplasty for mitral stenosis. Aortic regurgitation is likely to be due to a bicuspid aortic valve, rheumatic disease, or an enlarged aortic annulus.[ 29 ] Because of the physiological decrease in systemic vascular resist- ance, both of these lesions are generally well tolerated during pregnancy. For those pregnant women with symptoms and left ventricular dysfunction, there is well-established, eff ective medical management with diuretics, digoxin, and vasodilator therapy. Although angiotensin-converting enzyme (ACE) inhibitors are contraindicated during pregnancy, nitrates and hydralazine are eff ective substitutes when vasodilata- tion is the required eff ect.[ 29 ] Because women with valvar regurgitation generally do well during preg- nancy (see Chapter 13 ), and because prosthetic valves carry particular risks during pregnancy, there is no rec- ommendation for prepregnancy prophylactic replace- ment of mitral or aortic valves in women with severe regurgitation but no other established indications for surgery. Intervention during pregnancy should be
undertaken only for severely symptomatic women who are refractory to optimal medical therapy. When surgery is needed, it is usually because of sudden dete- rioration, such as in endocarditis or dissection. Some adaptations to cardiopulmonary bypass techniques may help lower the risk of fetal death,[ 21 ] but at this time there is no percutaneous alternative to open heart surgical cardiopulmonary bypass repair for mitral regurgitation or aortic regurgitation. Preliminary work on percutaneous aortic valve replacement and mitral valve repair is at much too early a stage to pre- dict its future role in interventions during pregnancy .
Prosthetic valves
Th e challenges of management of a pregnant woman with a prosthetic valve are discussed in Chapter 11 . Interventions in pregnant women with a prosthetic valve may be considered in the setting of valve thrombosis,