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ORIGINAL ARTICLE
Year : 2021  |  Volume : 24  |  Issue : 8  |  Page : 1138-1143

Risk Factors for Maternal and Perinatal Complications during Pregnancy among Women with Tetralogy of Fallot


Department of Obstetrics and Gynecology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China

Date of Submission22-Jun-2020
Date of Acceptance30-Nov-2020
Date of Web Publication14-Aug-2021

Correspondence Address:
Dr. J H Lin
Department of Obstetrics and Gynecology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, No. 160, Pujian Road, Pudong New District, Shanghai
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_378_20

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   Abstract 


Background: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease during pregnancy. Studies of risk factors are of great significance to maternal and fetal outcomes in patients with TOF. Aims: To identify predictive risk factors for maternal and perinatal complications in women with TOF. Subjects and Methods: 78 patients with TOF who delivered at Shanghai Obstetrical Cardiology Intensive Care Center between January 1993 and December 2017 were retrospective reviewed. A logistic regression model was used to identify risk factors for maternal and perinatal complications. Results: There was no maternal death, five patients developed cardiac failure, sustained arrhythmias requiring treatments were recorded among 2 patients. Factors identified for maternal complications included previous cardiac events and oxygen saturation <90%. Oxygen saturation <90% was found to be independent predictor of maternal cardiac complications (RR = 21.455, 95%CI 2.186–210.572, P = 0.009). The perinatal survival rate was 87.18%, there were 52 term deliveries (66.67%). Perinatal poor outcomes include 9 therapeutic abortions (11.54%), 1 neonatal death (1.28%), 16 premature births (20.51%), 18 small for gestational age children (23.08%), 3 neonatal asphyxia (3.85%), and 3 neonatal cardiac malformations (3.85%). Factors identified for perinatal complications included without cardiac surgery, higher hemoglobin values, higher hematocrit values, oxygen saturation <90%, right ventricular hypertrophy, pulmonary stenosis, ventricular septal defect, and pulmonary hypertension. Oxygen saturation <90% was found to be independent predictor of perinatal complications (RR = 8.270, 95%CI 1.374–49.790, P = 0.021). Conclusions: Oxygen saturation <90% is associated with maternal and perinatal risks. Women with TOF whose oxygen saturation <90% are not recommended for pregnancy because of high maternal and perinatal complications.

Keywords: Maternal complications, perinatal complications, pregnancy, risk factors, tetralogy of Fallot


How to cite this article:
Huang T T, Zhao W X, Lin J H. Risk Factors for Maternal and Perinatal Complications during Pregnancy among Women with Tetralogy of Fallot. Niger J Clin Pract 2021;24:1138-43

How to cite this URL:
Huang T T, Zhao W X, Lin J H. Risk Factors for Maternal and Perinatal Complications during Pregnancy among Women with Tetralogy of Fallot. Niger J Clin Pract [serial online] 2021 [cited 2022 Jun 30];24:1138-43. Available from: https://www.njcponline.com/text.asp?2021/24/8/1138/323852




   Introduction Top


Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, occurring in approximately 1 in 3,500 births and accounting for 7–10% of all congenital heart disease.[1] TOF is characterized by pulmonary stenosis, ventricular septal defect, overriding, or dextroposition of the aorta and right ventricular hypertrophy. In the past decades, the overall prognosis of CHD has been greatly improved and many patients could reach adulthood because of early diagnosis and timely therapy. However, TOF as a complex and cyanotic type of CHD, its prognosis remain poor, especially in those who did not undergo surgical repair. Women with unrepaired TOF are prohibited to be pregnant because of high mortality.[2] But some patients still get pregnant because they are eager to have children or do not know they have TOF. Therefore, heart failure, arrhythmias, sudden cardiac death, fetal intrauterine hypoxia, abortion, premature delivery, prenatal death may occur during pregnancy.[3]

To date, the outcomes of pregnant women with TOF have not well characterized because of limited number of studied cases and lack of data for close follow-up in China. We therefore analyzed the clinical data of 78 women with TOF who gave birth at the Shanghai Obstetrical Cardiology Intensive Care Center January 1993 and December 2017 so as to identify the risk factors for maternal and perinatal complications in pregnant women with TOF.


   Subjects and Methods Top


Following the approval of the ethics committee was obtained, a total of 78 pregnant women with TOF were identified between January 1993 and December 2017. All were supervised in the cardio-obstetric clinic under joint supervision of obstetrician and cardiologist. Cardiac diagnosis was established by electrocardiogram and echocardiography. NYHA class was defined in accordance with the NYHA functional classification.[4]

Baseline data had been collected before pregnancy or at the first prenatal visit. Subsequent data collection occurred during follow-up visits until 6 weeks after delivery. Information assessed included maternal age, parity, pregnancy history, gestational age, previous cardiac events (cardiac failure or sustained symptomatic arrhythmia before pregnancy), previous cardiac surgery, cardiac medication use, family history, NYHA functional classification, physical examination results (heart rate, blood pressure, breathing rate, cyanosis, clubbed finger, cardiac murmur and pulmonary rales), laboratory values (hemoglobin, hematocrit, central venous pressure and oxygen saturation of blood), 12-lead extrocardiography, Holter monitoring electrocardiogram, and echocardiography.

Maternal cardiac complications were defined as cardiac failure, sustained arrhythmia requiring treatment, stroke, pulmonary embolism, cardiac arrest, or cardiac death. Perinatal complications include premature birth (<37 weeks gestation), small for gestational age (<10th birth-weight percentile), respiratory distress syndrome, neonatal malformation, neonatal death within 28 days after birth.[5] All women were followed up to 42 days after delivery.

The data were analyzed using SPSS version 21.0 (SPSS Inc, Chicago, IL, USA). Baseline data are expressed as means with standard deviations; categorical data are expressed as percentages. Comparison of measurement data was performed using the t-test. Comparison of enumeration data was performed using the Chi-square test. A univariate logistic regression model was used to identify risk factors for maternal and perinatal complications. The prospective risk factors identified in the univariate analysis were then included in a multivariate logistic regression model to determine which factors remained statistically significant (P < 0.05).


   Results Top


Seventy-eight pregnant women with TOF were identified and analyzed in this study. The mean age of these 78 women was 27.14 ± 4.52 years range from 19 to 39 years. Seventy-two patients (92.3%) were primiparas while the others were multipara. Fifty-five patients (70.5%) had regular prenatal care and 23 (29.5%) not. Cardiac surgery had been performed before pregnancy among 54 patients (69.2%), three (3.8%) had undergone operations for two times. The average time from surgery to this pregnancy were 15.35 ± 7.60 years, with a year range from 2 to 27 years. Three women (3.85%) had previous cardiac events (two women had cardiac failure and one woman had sustained symptomatic arrhythmia need hospitalization). The gestational ages of these patients when admitted to our hospital were as follows: eight patients were <20 weeks (10.3%), one patient was between 20 weeks and 27 weeks and 6 days (1.3%), 20 patients were between 28 weeks and 36 weeks and 6 days (25.6%), and 49 patients were ≥37 weeks (62.8%). Of the 78 patients, 76 patients had a NHYA functional class of I–II (97.4%) and 2 patients had a NHYA functional class of III (2.6%) before pregnancy. The average hospital days were 10.29 ± 4.85 days.

Among the 78 pregnancies, nine patients ended in a therapeutic abortion (11.54%). Three patients had undergone cardiac surgery before pregnancy but still had residual cardiac defects such as right ventricular outflow obstruction, septal recanalization, and pulmonary hypertension. Other 6 women were diagnosed TOF by echocardiography and without cardiac surgery before pregnancy. All these patients had severe hypoxemia and pulmonary hypertension and they were prohibited to be pregnant.

Cardiac failures were recorded among 5 patients (6.4%). All 5 patients were primiparas; they all didn't have regular prenatal care during pregnancy. Three patients didn't undergo cardiac surgery before pregnancy; two patients had undergone partial cardiac corrective surgery before pregnancy and still had residual cardiac defects such as pulmonary stenosis, pulmonary regurgitation, septal recanalization, tricuspid regurgitation, and pulmonary hypertension. The five patients were admitted to hospital for emergency treatment, digitalis diuretics, and vasodilators were given to treat heart failure, and cesarean section was done later. Sustained arrhythmias requiring treatments were recorded among 2 patients (2.6%). One patient had paroxysmal ventricular tachycardia and amiodarone was needed, another patient had atrial fibrillation and digoxin and warfarin were needed. Cardiac death, cardiac arrest, pulmonary embolism did not occur in this cohort.

We analyzed the relationship between cardiac complications and baseline information laboratory parameters and echocardiography data. A univariate logistic regression model was used to identify potential risk factors for maternal cardiac complications. This analysis identified two factors with an OR greater than 1. These two factors included previous cardiac events (cardiac failure or sustained symptomatic arrhythmia before pregnancy) and oxygen saturation <90% [Table 1]. These potential risk factors were entered into a multivariate logistic regression model, oxygen saturation <90% was found to be independent predictor of maternal cardiac complications (RR = 21.455, 95%CI 2.186–210.572, P = 0.009).
Table 1: Risk factors to predict maternal cardiac complications

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Among 78 patients, there were 68 live births (87.18%), with a mean gestational age of 263.12 ± 13.00 days and a mean birth weight of 2688.93 ± 658.12 g. In women without cardiac surgery, the neonatal survival rate is 70.8% (17/24). Live births at term were recorded for 52 women (66.67%). There were 9 therapeutic abortions (11.54%), 1 neonatal death (1.28%), 16 premature births (20.51%) with a mean gestational age of 244.38 ± 12.10 days, 18 small for gestational age children (23.08%) with a mean birth weight of 1988.44 ± 470.86 g, 3 neonatal asphyxia (3.85%) and 3 neonatal cardiac malformations (3.85%). Here is the information of the three neonatal cardiac malformations: First patient delivered at 40+3 weeks of gestation, the neonatal birth weight was 2005 g and had atrial septal defect. Second patient delivered at 32+5 weeks of gestation, the neonatal birth weight was 1540 g and had ventricular septal defect, complete endocardial cushion defect and common atrioventricular valve. The baby died after 2 h. Third patient delivered at 34+3 weeks of gestation, the neonatal birth weight was 1415 g and had ventricular septal defect, neonatal scleroderma. No unifying genetic syndrome was identified.

A univariate logistic regression model was used to identify potential risk factors for perinatal complications. Factors identified included without cardiac surgery, higher hemoglobin values, higher hematocrit values, oxygen saturation <90%, right ventricular hypertrophy, pulmonary stenosis, ventricular septal defect, and pulmonary hypertension [Table 2]. Univariate analysis of factors (P < 0.05) were entered into a multivariate logistic regression analysis. Oxygen saturation <90% was found to be independent predictor of perinatal complications (RR = 8.270, 95%CI 1.374–49.790, P = 0.021).
Table 2: Risk factors to predict perinatal complications

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   Discussion Top


TOF is a severe type of CHD and it is characterized by the hemodynamic alterations because of anatomic abnormality. Due to the extra cardiac load during pregnancy, women with TOF had much higher maternal and perinatal morbidity compared to general population. So, it is worthwhile to identify risk factors for maternal and perinatal complications in these patients.

In our study, cardiac complications occurred in 7 patients with the incidence of 8.97%, with more cardiac failure (5/7) and less arrhythmia (2/7). In 2004, Veldtman et al. demonstrated 43 patients with TOF with their 112 pregnancies, the incidence of cardiac complications was 7%, supraventricular tachycardia in two, heart failure in two, pulmonary embolism in one, and progressive RV dilation in one.[6] In 2011, Ali Balci et al. demonstrated 74 patients with repaired TOF with their 157 pregnancies, the incidence of cardiac complications was 8.1%, mainly supraventricular arrhythmias.[7] The two results were similar to our study. But in 2012, in Kamiya's study, the incidence of cardiac complications such as a decline in NYHA class and arrhythmia was 17.5% (7/40), which was higher than ours.[8]

In our study, five patients with heart surgery had cardiac complications during pregnancy, three patients had cardiac failure and two patients had arrhythmia. Several reports have described a total of 68 pregnancies in patients with a corrected TOF, no complications were reported in these 68 pregnancies, in contrast to our series.[9],[10],[11],[12],[13] But in recent years, rates of 7–17.5% have been reported for maternal cardiac complications during pregnancy after repaired TOF, predominately supraventricular arrhythmias.[6],[7],[14] So women with repaired TOF are still at increased risk of cardiovascular events during pregnancy. The increased risk may be attributed to the extra hemodynamic burden and exacerbation of residual cardiovascular lesions, or recurrence of right ventricular outflow obstruction, right ventricular dilatation, pulmonary regurgitation, the right ventricular dilatation and failure, as well as atrial and ventricular arrhythmia.

Siu's first summarized independent risk factors of pregnant women with heart disease through a prospective study of 562 pregnant women with congenital or acquired heart disease. The potential predictors of maternal morbidity include: functional class, ventricular dysfunction, significant arrhythmias, cyanosis, outflow tract obstruction, pulmonary hypertension, and need for anticoagulants.[5] In women with TOF, several reports have shown that use of cardiac medication pre-pregnancy, history of arrhythmia, severe pulmonary hypertension, prior pulmonary valve replacement and severe pulmonary regurgitation (PR) and right ventricular dysfunction were predictors of maternal cardiac complications.[6],[7] In contrast to others, in our study, oxygen saturation <90% was an independent risk factor to predict cardiac complications of patients with TOF, oxygen saturation <90% is associated with maternal risks. In 2012, we analyzed 529 women with CHD and oxygen saturation <90% was also found to be significantly predictive for maternal cardiac complications.[15]

Several reports have shown that in patients with TOF, perinatal complications include spontaneous abortion, fetal/neonatal death, and small for gestational age children, neonatal asphyxia, premature birth, and congenital heart disease in the fetus.[16] In our study, there was 1 neonatal death, 9 therapeutic abortions. The rate of fetal loss is 12.82%. In 2004, Veldtman et al. described 43 patients with TOF with their 112 pregnancies, the fetal loss rate was 24%[6]; In 2008, Pedersen et al. reported 25 patients with their 54 pregnancies, the fetal loss rate was 15%[17]; In 2011, Balci et al. reported 19% of the pregnancies ended in a spontaneous abortion, which are higher than ours.[7]

In our study, oxygen saturation <90% was the independent risk factor to predict perinatal complications, oxygen saturation <90% is associated with perinatal risks. When maternal cyanosis occurs, comparatively low maternal oxygen saturation would lead to low fetal oxygen supplement and result in perinatal complications. At the same time, we found the higher the level of maternal hemoglobin and hematocrit were, the greater the probability of perinatal complications was. In 1994, Presbiter et al. demonstrated the most important risk factor for adverse perinatal outcome was the degree of cyanosis.[18] The fetal mortality is associated with high level of maternal hematocrit and low oxygen saturation. These authors suggested that an arterial oxygen saturation >85% and hemoglobin concentration ≤18 g/dl were more likely to result in live birth. When maternal hemoglobin concentration was >20 g/dl and oxygen saturation was <85%, the live birth rate of neonatal was only 12%. Also, in other reports, use of maternal cardiac medication before pregnancy and pregnancies with palliative surgical intervention before correction are the risk factors to predict perinatal complications.[7]

The risk of recurrence of congenital heart disease in women with TOF has been reported to range from 0% to 9.8%.[6],[11],[13],[17],[19] In our series, 3.85% of the infants had congenital anomalies, including atrial septal defect, ventricular septal defect, complete endocardial cushion defect and common atrioventricular valve. The rate is higher than the prevalence of congenital anomalies in the general population, which is approximately 3%, and was similar to the rate of 4% in Zellers' study.[19] So we suggest that patients with severe cardiac disease should have fetal echocardiography during pregnancy.

Since the establishment of Shanghai Obstetrical Cardiology Intensive Care Center in Shanghai Renji Hospital from 1993, based on the strength of the comprehensive hospital, we have admitted a large number of pregnant women with heart disease and have good rescue capability. Under the premise of patients' understanding of the risks of disease and pregnancy, 87.18% of the patients with TOF delivered successfully on the basis of closely monitoring and health care during pregnancy. From our experience, women with TOF whose oxygen saturation <90% are not recommended for pregnancy because of high maternal and perinatal complications. The oxygen saturation test is a simple and operable clinical examination item, which is very convenient. Women with uncorrected TOF may still be able to have a successful pregnancy, but exclusively depending on professional care from multidisciplinary teams. Whenever possible, heart defects should be surgically corrected before conception. Antenatal care should be managed by multidisciplinary including an obstetrician, a cardiologist, a perinatologist, and an anesthetist. They should fully assess the patients before pregnancy, monitor heart function strictly during pregnancy, handle the appropriate time and mode of delivery, way of anesthesia, hemodynamic monitoring during childbirth, the use of medicine and post-natal care.[20],[21] Woman at highest risk may benefit from preconception counseling and close clinical monitoring during pregnancy.[22]

But our article has limitations. The incidence of cardiovascular disease during pregnancy is 1–4%, TOF is accounting for 7–10% of all congenital heart disease, its prognosis remains poor. So the number of women with TOF who get pregnant is relatively small. The sample size of women with TOF in our article is only 78, so the conclusions of our article are for reference only, we should collect more cases to validate the work enough in the future.

Financial support and sponsorship

The authors disclosed receipt of the following financial support for publication of this article: The National “Twelfth-Five Year” Research and Development Program of China, No. 2014BAI05B05.

Conflicts of interest

The authors have no conflicts of interest.



 
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