Temporary pacing during delivery is recommended in selected women with complete heart block and symp- toms due to the risk of bradycardia and syncope. Th e risks of permanent pacemaker implantation (preferably one chamber) are generally low. Implantation can be per- formed safely—especially aft er the fi rst trimester.[ 46 ]
Maternal mortality during cardiopulmonary bypass is now similar to that in nonpregnant women who undergo comparable cardiac procedures.[ 47 ] However, there is signifi cant morbidity, including late neurological impairment in 3–6% of children, and a high fetal mortality rate.[ 48 ]
For this reason, cardiac surgery is recommended only when medical therapy or interventional proce- dures fail and the mother’s life is at risk. Surgery in the fi rst trimester carries a higher risk of fetal malforma- tion. Th e optimum period for surgery is the second trimester, when organogenesis is complete. During the third trimester, there is a higher incidence of pre- term delivery and maternal complications. Th erefore, surgery is advised only in extreme cases in which there is failed medical treatment. Contributing risk factors include the use of vasoactive drugs, other preopera- tive medication, age, nature of surgery, reoperation, and functional class. Overall, functional class is the best predictor for adverse maternal outcome.[ 49 ] In a systematic review of the outcomes of 161 women undergoing cardiac surgery during pregnancy, fetal morbidity and mortality were 9% and 30%, respect- ively, and maternal morbidity and mortality were 24%
and 6%, respectively .[ 47 ]
In women with signifi cant mitral stenosis (mitral valve area <1.0 cm 2 ) and more than NYHA class II despite aggressive medical therapy, urgent surgical intervention to relieve the stenosis should be con- sidered. Percutaneous balloon mitral valvuloplasty and closed valvotomy have been safely performed in pregnancy.[ 50 ] However, the eff ect of the use of radio-opaque contrast agents on the fetus remains
unknown. Fluoroscopy and cineangiography times need to be as brief as possible and the gravid uterus should be shielded from direct radiation .[ 51 ]
Cardiopulmonary bypass produces a nonphysi- ological state that alters the cellular components of blood and adversely aff ects the coagulation factors.
Th is results in the release of vasoactive substances from leukocytes and complement activation.[ 51 ] Th e uteroplacental blood fl ow is directly proportional to the maternal mean arterial pressure and inversely pro- portional to the uterine vascular resistance. Maternal hypotension can signifi cantly reduce placental perfu- sion and result in fetal loss. Combined with nonpulsatile perfusion, uterine arteriovenous shunts, obstruction of inferior vena cava drainage, uterine artery spasm, and particulate and gaseous embolism, this can lead to fetal hypoxia, bradycardia, and even death. In addi- tion, hypothermia can cause fatal fetal arrhythmias.
Maternal alkalosis during cardiopulmonary bypass can shift the maternal oxyhemoglobin dissociation curve to the left , leading to reduced fetal partial arte- rial oxygen pressure and oxygen content. A minimum maternal hematocrit of 28% is recommended to opti- mize the oxygen delivery. Cardiopulmonary bypass time should be minimized .[ 52 , 53 ]
Eff ects of anesthetic drugs on the fetus
All anesthetic drugs administered to pregnant women will rapidly cross the placenta and be distributed to the fetus. Most of the commonly used induction agents, narcotics, and muscle relaxants are safe in pregnancy.
Halothane will equilibrate in fetal tissues aft er 60 min of maternal exposure and is associated with stable fetal hemodynamics and acid–base response. However, iso- fl urane will produce a reduction in fetal cardiac output and redistribution of fetal circulation away from the placenta. Prolonged exposure to isofl urane can lead to hypercarbic acidosis in sheep fetuses. [ 54 ]
Fetal monitoring during surgery
Fetal heart-rate monitoring will help guide the manage- ment of maternal cardiorespiratory parameters.[ 55 ] Anesthetic drugs can create a loss of fetal heart-rate variability by anesthetizing the brainstem center that modulates intrinsic cardiac automaticity. Th ey can thus infl uence the interpretation of fetal monitoring. Abrupt changes in heart rate and baseline rates outside the accept- able range of 110–160 beats/min should prompt the anesthetist to look for obvious causes of uteroplacental
insuffi ciency and implement measures to increase blood pressure and oxygen delivery to the mother .
High-pressure, high-fl ow cardiopulmonary bypass is recommended for the management of cardiac sur- gery in pregnant women.[ 56 ] Successful fetal outcome has been reported using mean pump pressures above 60 mmHg and fl ows above 2.0 l/min/m 2 . Systemic cool- ing to temperatures below 28°C carries a high risk of fetal cardiac arrest and demise. It is now possible to use systemic normothermia on bypass to minimize the risk of hypothermia.[ 57 ] However, despite high peak fl ows, normal mean arterial pressure and normothermia, fetal outcome is still dismal. Th is is related to changes in fetal and uterine hemodynamics during surgery.
Intraoperative fetal bradycardia is oft en observed aft er aortic clamping with a rise in the UA PI and a nonpul- satile uterine artery fl ow noted.[ 58 ] Th erefore, there may be a role for fetal heart-rate monitoring during surgery. Th e variables of the maternal bypass perfusion are adjusted according to the fetal heart-rate pattern observed in order to limit the eff ects of bypass on the fetus as much as possible. However, if fetal monitor- ing is used, the best method of surveillance, whether by CTG, ultrasound or Doppler assessment of umbil- ical and uterine arteries, remains controversial. When pregnant women lie in the supine position, the uterus can compress the inferior vena cava and interfere with venous return to the heart. Th is can result in hypo- tension, reduced placental perfusion, and decreased fetal oxygenation. Hence, use of a lateral table or pel- vic tilt to reduce supine aortocaval compression is recommended .
In cases in which there is fetal or maternal com- promise, cesarean delivery while on cardiac bypass has been reported. However, the decision for immediate delivery is dependent on the gestational age and viabil- ity of the fetus. Neonatal mortality is 90% at 25 weeks of gestation and decreases to about 15% by week 30.[ 59 ] Premature labor presents the greatest risk to the fetus in the perioperative period. Th e benefi ts of postponing surgery until the second trimester to allow adequate fetal lung maturation should be balanced against the potential hazards to the mother .
References
1. Cantwell R , Clutton-Brock T , Cooper G et al. Saving mothers’ lives: Reviewing maternal deaths to make motherhood safer: 2006–2008. Th e eighth report of the confi dential enquiries into maternal deaths in the UK . BJOG 2011 ; 188 ( Suppl 1 ): 1 – 203 .
Section 3: Antenatal Care: Fetal Considerations
2. Nieminen HP , Jokinen EV , Sairanen HI . Late results of pediatric cardiac surgery in
Finland: A population-based study with 96% follow-up . Circulation . 2001 ; 104 : 570–5 .
3. Papageorghiou AT , Yu CKH , Bindra R , Pandis G , Nicolaides KN . Multicentre screening for pre-eclampsia and fetal growth restriction by transvaginal uterine artery Doppler at 23 weeks of gestation . Ultrasound Obstet Gynecol 2001 ; 18 : 441–9 .
4. Clark SL . Cardiac disease in pregnancy . Obstet Gynecol Clin North Am 1991 ; 18 : 237–56 .
5. Clark SL . Labor and delivery in the patient with structural cardiac disease . Clin Perinatol 1986 ; 13 : 695 – 703 .
6. Siu SC , Sermer M , Harrison DA , et al. Risk and predictors for pregnancy-related complications in women with heart disease . Circulation 1997 ; 96 : 2789–94 .
7. Curry RA , Fletcher C , Gelson E , et al. Pulmonary hypertension and pregnancy–a review of 12 pregnancies in nine women . Br J Obstet Gynaecol 2012 ; 119 : 752–61 .
8. Whittemore R , Hobbins JC , Engle MA . Pregnancy and its outcome in women with and without surgical treatment of congenital heart disease . Am J Cardiol 1982 ; 50 : 641–51 .
9. Presbitero P , Somerville J , Stone S , et al. Pregnancy in cyanotic congenital heart disease. Outcome of mother and fetus . Circulation 1994 ; 89 : 2673–6 .
10. Chia P , Raman S , Th am SW . Th e pregnancy outcome of acyanotic heart disease . J Obstet Gynaecol Res 1998 ; 24 : 267–73 .
11. Gleicher N , Midwall J , Hochberger D , et al.
Eisenmenger’s syndrome and pregnancy . Obstet Gynecol Surv 1979 ; 34 : 721–41 .
12. Sawhney H , Suri V , Vasishta K , et al. Pregnancy and congenital heart disease—maternal and fetal outcome . Aust N Z J Obstet Gynaecol 1998 ; 38 : 266–71 .
13. Pedersen LM , Pedersen TA , Ravn HB , et al. Outcomes of pregnancy in women with tetralogy of Fallot . Cardiol Young 2008 ; 18 : 423–9 .
14. Canobbio MM , Mair DD , van der Velde M , et al.
Pregnancy outcomes aft er the Fontan repair . J Am Coll Cardiol 1996 ; 28 : 763–7 .
15. Hameed AH , Karaalp IS , Tummala PP , et al. Th e eff ect of valvular heart disease on maternal and fetal outcome of pregnancy . J Am Coll Cardiol 2001 ; 37 : 893–9 . 16. Malhotra M , Sharma JB , Tripathii R , et al. Maternal and
fetal outcome in valvular heart disease . Int J Gynaecol Obstet 2004 ; 84 : 11 – 16 .
17. Burn J , Brennan P , Little J , et al. Recurrence risks in off spring of adults with major heart defects: Results
from fi rst cohort of British collaborative study . Lancet 1998 ; 351 : 311–16 .
18. Nora JJ . From generational studies to a multilevel genetic-environmental interaction . J Am Coll Cardiol 1994 ; 23 : 1468–71 .
19. Gill HK , Splitt M , Sharland GK , Simpson JM . Patterns of recurrence of congenital heart disease: An analysis of 6,640 consecutive pregnancies evaluated by detailed fetal echocardiography . J Am Coll Cardiol 2003 ; 42 : 923–9 .
20. Nora JJ , Nora AH . Th e evolution of specifi c genetic and environmental counseling in congenital heart diseases . Circulation 1978 ; 57 : 205–13 .
21. Hyett J , Moscoso G , Nicolaides K . Abnormalities of the heart and great arteries in fi rst trimester chromosomally abnormal fetuses . Am J Med Genet 1997 ; 69 : 207–16 .
22. Moyano D , Huggon IC , Allan LD . Fetal
echocardiography in trisomy 18 . Arch Dis Child Fetal Neonatal Ed 2005 ; 90 : F520–2 .
23. Surerus E , Huggon IC , Allan LD . Turner’s syndrome in fetal life . Ultrasound Obstet Gynecol 2003 ; 22 : 264–7 . 24. Hyett J , Perdu M , Sharland G , et al. Using fetal nuchal
translucency to screen for major congenital cardiac defects at 10–14 weeks of gestation: Population based cohort study . BMJ 1999 ; 318 : 70–1 .
25. Makrydimas G , Sotiriadis A , Huggon IC , et al. Nuchal translucency and fetal cardiac defects: A pooled analysis of major fetal echocardiography centers . Am J Obstet Gynecol 2005 ; 192 : 89 – 95 .
26. Mogra R , Alabbad N , Hyett J . Increased nuchal translucency and congenital heart disease . Early Hum Dev 2012 ; 88 : 261–7 .
27. Atzei A , Gajewska K , Huggon IC , et al. Relationship between nuchal translucency thickness and prevalence of major cardiac defects in fetuses with normal karyotype . Ultrasound Obstet Gynecol 2005 ; 26 : 154–7 . 28. Huggon IC , Ghi T , Cook AC , et al. Fetal cardiac
abnormalities identifi ed prior to 14 weeks’ gestation . Ultrasound Obstet Gynecol 2002 ; 20 : 22–9 .
29. Maiz N , Plasencia W , Dagklis T , et al. Ductus venosus Doppler in fetuses with cardiac defects and increased nuchal translucency thickness . Ultrasound Obstet Gynecol 2008 ; 31 : 256–60 .
30. Pereira S , Ganapathy R , Syngelaki A , et al. Contribution of fetal tricuspid regurgitation in fi rst-trimester screening for major cardiac defects . Obstet Gynecol 2011 ; 117 : 1384–91 .
31. Rasiah SV , Publicover M , Ewer AK , et al. A systematic review of the accuracy of fi rst-trimester ultrasound examination for detecting major congenital heart disease . Ultrasound Obstet Gynecol 2006 ; 28 : 110–16 .
32. Khalil A , Nicolaides KH . Fetal heart defects: Potential and pitfalls of fi rst-trimester detection . Semin Fetal Neonatal Med 2013 ; 18 : 251–60 .
33. Gelson E , Curry R , Gatzoulis MA , et al. Eff ect of maternal heart disease on fetal growth . Obstet Gynecol 2011 ; 117 : 886–91 .
34. Papageorghiou AT , Yu CK , Nicolaides KH . Th e role of uterine artery Doppler in predicting adverse pregnancy outcome . Best Pract Res Clin Obstet Gynaecol 2004 ; 18 : 383–96 .
35. Carbillon L , Challier JC , Alouini S , et al. Uteroplacental circulation development: Doppler assessment and clinical importance . Placenta 2001 ; 22 : 795–9 . 36. Sagol S , Ozkinay E , Oztekin K , et al. Th e comparison
of uterine artery Doppler velocimetry with the histopathology of the placental bed . Aust N Z J Obstet Gynaecol 1999 ; 39 : 324–9 .
37. Neilson JP , Alfi revic Z . Doppler ultrasound for fetal assessment in high-risk pregnancies . Cochrane Database Syst Rev 2000 ;( 2 ): CD000073 . 38. Madazli R , Somunkiran A , Calay Z , et al.
Histomorphology of the placenta and the placental bed of growth restricted foetuses and correlation with the Doppler velocimetries of the uterine and umbilical arteries . Placenta 2003 ; 24 : 510–16 .
39. Karsdorp VH , van Vugt JM , Van Geijn HP , et al.
Clinical signifi cance of absent or reversed end diastolic velocity waveforms in umbilical artery . Lancet 1994 ; 344 : 1664–8 .
40. Pattinson RC , Norman K , Odendaal HJ . Th e role of Doppler velocimetry in the management of high-risk pregnancies . Br J Obstet Gynaecol 1994 ; 101 : 114–20 . 41. Todros T , Ronco G , Fianchino O , et al. Accuracy
of the umbilical arteries Doppler fl ow velocity waveforms in detecting adverse perinatal outcomes in a high-risk population . Acta Obstet Gynecol Scand 1996 ; 75 : 113–19 .
42. Baschat AA . Neurodevelopment following fetal growth restriction and its relationship with antepartum parameters of placental dysfunction . Ultrasound Obstet Gynecol 2011 ; 37 : 501–14 .
43. Baschat AA , Gembruch U , Reiss I , et al. Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction . Ultrasound Obstet Gynecol 2000 ; 16 : 407–13 .
44. Bilardo CM , Wolf H , Stigter RH , et al. Relationship between monitoring parameters and perinatal outcome in severe, early intrauterine growth restriction . Ultrasound Obstet Gynecol 2004 ; 23 : 119–25 .
45. Coomarasamy A , Fisk NM , Gee H , et al. Investigation and Management of the Small-for-Gestational Age Fetus. Guideline No. 31 . London : Guidelines and Audit
Committee of the Royal College of Obstetricians and Gynaecologists , 2002 .
46. Suri V , Keepanasseril A , Aggarwal N , et al. Maternal complete heart block in pregnancy: Analysis of four cases and review. of management . J Obstet Gynaecol Res 2009 ; 35 : 434–7 .
47. Weiss BM , von Segesser LK , Alon E , et al. Outcome of cardiovascular surgery and pregnancy: A systematic review of the period 1984–1996 . Am J Obstet Gynecol 1998 ; 179 : 1643–53 .
48. Chambers CE , Clark SL . Cardiac surgery during pregnancy . Clin Obstet Gynecol 1994 ; 37 : 316–23 . 49. Pomini F , Merccogliano D , Cavaletti C , et al.
Cardiopulmonary bypass in pregnancy . Ann Th orac Surg 1996 ; 61 : 259–68 .
50. Kalra GS , Arora R , Khan JA , et al. Percutaneous mitral commissurotomy for severe mitral stenosis during pregnancy . Cathet Cardiovasc Diagn 1994 ; 33 : 28 – 30 .
51. Mahli A , Izdes S , Coskun D. Cardiac operations during pregnancy: Review of factors infl uencing fetal outcome . Ann Th orac Surg 2000 ; 69 : 1622–6 .
52. Sepehripour AH , Lo TT , Shipolini AR , et al. Can pregnant women be safely placed on cardiopulmonary bypass ? Interact Cardiovasc Th orac Surg
2012 ; 15 : 1063–71 .
53. Chandrasekhar S , Cook CR , Collard CD . Cardiac surgery in the parturient . Anesth Analg 2009 ; 108 : 777–85 .
54. Cheek DB , Hughes SC , Dailey PA , et al. Eff ect of halothane on regional cerebral blood fl ow and cerebral metabolic oxygen consumption in the fetal lamb in utero . Anesthesiology 1987 ; 67 : 361–6 .
55. Liu PL , Warren TM , Ostheimer GW , et al. Foetal monitoring in parturients undergoing surgery unrelated to pregnancy . Can Anaesth Soc J 1985 ; 32 : 525–32 .
56 . Conroy JM , Bailey MK , Hollon MF , et al. Anesthesia for open heart surgery in the pregnant patient . South Med J 1989 ; 82 : 492–5 .
57. Salerno TA , Houck JP , Barrozo CA , et al. Retrograde continuous warm blood cardioplegia: A new concept in myocardial protection . Ann Th orac Surg 1991 ; 51 : 245–9 .
58. Khandelwal M , Rasanen J , Ludormirski A , Addonizio P , Reece EA . Evaluation of fetal and uterine
hemodynamics during maternal cardiopulmonary bypass . Obstet Gynecol 1996 ; 88 : 667–71 .
59. Draper ES , Manktelow B , Field DJ , James D. Prediction of survival for preterm births by weight and gestational age: Retrospective population based study . BMJ 1999 ; 319 : 1093–7 .
Heart Disease and Pregnancy, 2nd edn. ed. Philip J. Steer and Michael A. Gatzoulis. Published by Cambridge University Press.
© Cambridge University Press 2016.