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A five year retrospective study on maternal and perinatal outcome in pregnancy after cardiac surgery

Pregnancy makes a significant impact on cardiovascular system. It is important to evaluate and study the effect of pregnancy on women with surgically corrected heart conditions so as to preempt potential complications. Pregnancies complicated with maternal cardiac diseases have an incidence of 1-4%. Most of these can be managed with lifestyle changes and medical management. Pregnancy following cardiac surgery puts both mother and fetus at risk. Maternal mortality rate can be as high as 10-30%. Pregnancy among women with mechanical prosthetic valve is associated with arisk of maternal death of between 1 and 4%. Thus patients with artificial heart valves need an enhanced level of care during pregnancy and labour. Mortality is mainly due to thrombotic complications. Neither surgical nor medical treatment is ideal for pregnant women with acute prosthetic heart valve dysfunction. Hence appropriate time and the mode of delivery prior to the therapy when ABSTRACT


INTRODUCTION
Pregnancy is a hypercoaguablestate with physiological haemodynamic changes occurring during pregnancy. 1,2 There is a progressive increase in intravascular volume in second trimester of pregnancy and increase in cardiac output. 3 Pregnancy makes a significant impact on cardiovascular system. It is important to evaluate and study the effect of pregnancy on women with surgically corrected heart conditions so as to preempt potential complications. Pregnancies complicated with maternal cardiac diseases have an incidence of 1-4%. Most of these can be managed with lifestyle changes and medical management. Pregnancy following cardiac surgery puts both mother and fetus at risk. Maternal mortality rate can be as high as 10-30%. 4 Pregnancy among women with mechanical prosthetic valve is associated with arisk of maternal death of between 1 and 4%. 5 Thus patients with artificial heart valves need an enhanced level of care during pregnancy and labour. 6 Mortality is mainly due to thrombotic complications. Neither surgical nor medical treatment is ideal for pregnant women with acute prosthetic heart valve dysfunction. Hence appropriate time and the mode of delivery prior to the therapy when the gestation age is beyond 32 weeks is preferred. Management also depends on maternal status. There is no contraindication for pregnancy in patients with NYHA (New York heart association) class I and II after cardiac surgery. However physiological changes in pregnancy put strain on cardiovascular system and many times it is hard to predict the consequences. In NYHA class III and IV, serious adverse cardiac events can be as high as 57%. 7 Patients with cardiac disease because of impaired circulation state may have hypoxia of myometrium and hence the risk of premature labour is high. 8 Pulmonary edema, cardiac arrthymias, postpartum haemorrhage and thromboembolic events increase the maternal morbidity. 8 The maternal and fetal outcome in women who had prior cardiac surgery can be improved with appropriate medical care. Awareness to general population, knowledge about progress of disease and effect of pregnancy on corrected heart conditions per se should be discussed in detail with the couple and family members prior to conception.

METHODS
This isa retrospective study of patients with prior history of cardiac surgery and their pregnancy outcomes in a tertiary center of Southern India over a period of five years from Jan 2011 to Dec 2016. Eighty seven pregnant women were studied and data was analyzed retrospectively for maternal and neonatal outcome. Variables reviewed were demographic data like maternal age, parity, successful live birth, obstetrics risk factors such as gestational hypertension, gestational diabetes on treatment, anemia and previous caesarean section, type of cardiac surgery, mode of delivery, postpartum complications. Neonatal outcomes noted were as follows : birth weight, APGAR score, need for Neonatal ICU admission. Types of cardiac surgery in this study population were mitral valve replacement, aortic valve repair, mitral and aortic valve repair, atrial septal defect and ventricular septal defect repair, repair of Tetralogy of Fallot. NYHA functional class [I to IV] of the women was documented in the study. Progression of functional class of NYHA from class 1 to 3and 4 makes potential difference in both maternal and fetal outcome. Descriptive statistical analysis was done.

RESULTS
Descriptive statistical analysis of 87 pregnant women with previous history of cardiac surgery was done and used to describe the data. Maternal age was ranging from 20 years to 39years. The mean age recorded in the study group was 25.6 years. Distribution in accordance with parity were as follows 58.6%were nullipara,19.5%were primipara, multiparous were 21.8%. According to the past obstetric score, we found one live child in 31% and 4.6% had 2 live children. Among 87 pregnant women, 11.5% had gestational diabetes and were on medical nutritional therapy or on medication during pregnancy, 6.9% women had associated gestational hypertension and mild preeclampsia. 10 pregnant women had previous bad obstetric history and 8 women had pregnancy complicated with anemia. 11.5% women had previous one or two lower segment caesarean sections.47.8% women had no associated obstetrical risk factors.  In patient on Warfarin, as per our hospital protocol heparin was given till 14 weeks of gestation and then was changed over to oral anticoagulant till 37 weeks and then heparin was given till delivery. Heparin was restarted after 12 hours of caesarean section and 6 hours after vaginal delivery. 6.8% pregnant women with heart surgery were on digoxin, diuretic and penicillin prophylaxis. 31% were on heparin/oral Anticoagulant medication, 12.6% women were on both anti-failure and anticoagulant medication.
Other variables studied were the mode of delivery, indication for caesarean section or reasons for operative vaginal deliveries, type of anaesthesia offered, total blood [pulmonary edema, severe preeclampsia with uncontrolled blood pressure leading to maternal compromise resulting in operative deliveries and intensive care unit admission]. General anaesthesia was offered to 14.1% and spinal anaesthesia to 24%. Blood loss more than a liter was found in 6 women, 4 women had uterine atonicity, traumatic postpartum heamorrhage was found in 2 cases. Postpartum puerperial complication like endomyometritis, urinary tract infection was seen in 3.3%. One woman had supraventricular tachycardia after delivery. Neonatal parameters studied were birth weight, APGAR score, Neonatal ICU admission. Birth weight after delivery was found to be less than 2.5 kg in 18.4% while 77% of babies' birth weight was more than 2.5 kg (Table  3). 14 babies were admitted in NICU. Reasons for NICU admission were low APGAR score, respiratory distress syndrome and sepsis.
Authors analyzed maternal variables before and after delivery. The occurrence of spontaneous abortion (upto 20 weeks of gestation), still birth, premature birth (birth upto 36 weeks and 6 days of gestation].75% women delivered at term [more than 37 weeks of gestation), preterm delivery in 18.3%. Out of this, late preterm between 34 to 36 weeks and 6 days of gestation were 14.9% and 3.4% in less than 33 weeks and 6 days Similarly, maternal ICU admission and subsequent successful pregnancy outcome were studied. ICU care was required for 6 mothers after delivery. Among 87 women with prior history of cardiac Surgery, 37.9% women had subsequent second successful pregnancy.

DISCUSSION
Heart disease in pregnancy is an indirectcause of maternal mortality. Rheumatic heart disease, congenital heart disease are more common than ischaemic heart disease and cardiomyopathy. Though there is significant decrease in occurence of rheumatic heart disease, the incidence of cardiac disease in pregnancy remained stable over many years. This is because of the significant increase in pregnancy in women with congenital heart disease. 4 Advances in cardiac surgery have significantly contributed to better level of functioning of the cardiovascular system and better quality of life for patients with both acquired and congenital heart disease.
Management of pregnant woman following cardiac surgery possess a significant challenge to an obstetrician. Maternal mortality is mainly due to complications like thromboembolic, haemorrhage and heart failure. Fetal complications are mainly due to teratogenic effects of anticoagulation and other drugs. Risk of hypoxia and intrauterine growth restriction is high in foetuses of women with cardiac disease.
Management of pregnancy following cardiac disease include assessment of the patient's symptoms, cardiac function and her functional capacity and also the type of surgery, valve prosthesis, anticoagulation status and anticoagulation drugs. 5 Continuing advancements in cardiac surgery and management of pregnancies in patients following cardiac surgery is easier now in view of improved functional capacity of the patient and fewer complications faced.
Nevertheless, close monitoring and insight of the anticipated medical problems in this group of patients is mandatory. There is additional circulatory burden on the heart due to haemodynamic changes of pregnancy which is maximum during intrapartum and immediate post partum. 8 Circulatory overload and the hypercoagulable state of pregnancy are the two difficult conditions which complicate the management. 9 The functional status of the woman prior to pregnancy is a better predictor of maternal and fetal outcome. Maternal morbidity is directly correlated with functional class. In this study, we found similar outcome. All the patients in our study belonged to NYHA class I and II. Majority of our study population (39%) had mitral valve replacement and the next in order was atrial septal defect repair (37%). 2.2% of the patients had repair for tetrology of fallot and 3.3% had aortic valve replacement.
Anticoagulation is indicated for patients with prosthetic valves due to risk of thrombosis. Change over from oral coumarins to heparin between 6-12 weeks gestation age, continuation of oral coumarins during the rest of pregnancy and then change over to heparin at 36 weeks is advocated. 9,10 This is done to avoid the teratogenic effects of coumarin and also as a precaution against postpartum