Early Results and Factors Affecting Arterial Switch Operation in Provincial Medical Center
Transposition of the great arteries (TGA) is a severe and complex congenital heart disease, accounting for 5% to 7% of all congenital heart malformations. Most fetuses with TGA can survive to delivery, but their postnatal survival depends on associated conditions such as ventricular septal defect (VSD), atrial septal defect (ASD), or patent ductus arteriosus (PDA). Without treatment, approximately 30% of infants with TGA die within the first week after birth, and 90% die within the first year. The arterial switch operation (ASO) is now recognized worldwide as an effective treatment for TGA, with good results achieved through this approach. However, the early implementation of ASO at our center was delayed, resulting in a small number of patients and high mortality rates initially. Over time, with the gradual improvement of surgical team skills, both the number of patients and survival rates have increased. The development and promotion of fetal echocardiography have also enabled more prenatal diagnoses of TGA. From pregnancy to delivery and surgery, children with TGA require close monitoring and multidisciplinary collaboration among medical staff.
This study retrospectively analyzed the data of 87 patients who underwent ASO from January 2014 to December 2019 at our center to identify major non-surgical factors affecting patient prognosis. The study was approved by the Ethics Committee of Shandong Provincial Hospital.
Patient Characteristics and Demographics
The patients were primarily from the local area and three neighboring southern regions. A high proportion of patients were from rural areas, and the rate of prenatal diagnosis was low. The proportion of vaginal deliveries and cesarean sections was similar. Notably, the proportion of affected patients who were the second child in their families was higher than the combined number of first and third children affected. Males constituted a higher proportion of patients, consistent with the overall incidence of TGA. The mortality rates associated with urban residence, prenatal diagnosis, cesarean section, being the first child in the family, and female sex were higher than those in the corresponding groups, but these differences were not statistically significant. Interestingly, prenatal diagnosis, which is generally associated with improved survival rates, showed the opposite trend in our study, similar to findings by Qu et al. This discrepancy may be due to some patients diagnosed after birth discontinuing treatment or dying before surgery, which could also explain why rural patients had lower mortality rates than urban patients. Additionally, the mortality rate of the second child in the family was significantly lower than that of the first or third child, a finding that warrants further investigation.
Preoperative Evaluation and Diagnosis
Before ASO, all patients were evaluated by the same senior echocardiography expert. While the coronary artery pattern could not be accurately described preoperatively, other diagnoses were consistent with intraoperative findings. The proportion of TGA with VSD (TGA-VSD) was 35.6% (31/87), aligning with the overall incidence of 40%. Among the patients, 84 had ASD or patent foramen ovale (PFO), and 69 had PDA. Additionally, four patients had pulmonary stenosis (PS), three had double outlet right ventricle (DORV), and three had coarctation of the aorta (CoA). The main coronary artery pattern followed the conventional pattern, defined according to the Leiden classification. The mortality rates for the TGA with intact ventricular septum (TGA-IVS) group and the unconventional coronary artery pattern group were higher than those in the corresponding groups, but the differences were not statistically significant, consistent with findings from Fricke et al. Thus, VSD complications and coronary artery patterns were not key factors affecting mortality at our center.
Preoperative Management and Risk Factors
Before ASO, prostaglandin E was administered to prevent PDA closure, and appropriate interventions were used to improve cardiac and respiratory function. Most patients were delivered at full-term, with only seven born prematurely between 34 and 36 weeks. Nineteen patients required mechanical ventilation (MV), fourteen required intensive care in the ICU due to critical conditions, and seven underwent rescue or emergency surgery. The mortality rates associated with premature birth, preoperative MV or ICU care, and rescue or emergency surgery were significantly higher than those in the corresponding groups, identifying these as important risk factors for postoperative death. The last six weeks of pregnancy are critical for fetal growth and development, and premature newborns often have low biological reserves, poor lung function, and low weight, increasing the risk of postoperative death. Therefore, it is recommended to deliver at 39 to 40 weeks of gestation unless obstetric indications suggest otherwise.
Balloon atrial septostomy (BAS) is not routinely performed at our center, despite its effectiveness in extending the waiting time before surgery. BAS carries risks such as femoral or umbilical vein trauma, atrial arrhythmia, complete cardiac block, and thromboembolic events in the brain. Most of our patients had VSD, ASD, PFO, or PDA, and during preoperative discussions, guardians often opted for emergency surgery over palliative treatment or dual-stage surgery. Only one male infant underwent dual-stage surgery, involving a modified B-T shunt and banding operation before ultimately undergoing ASO.
Surgical Details and Outcomes
All surgeries were performed by the same surgical team, with concurrent VSD, PDA, PS, and CoA repaired during the procedure. One exceptional case involved a 28-year-old patient with TGA concurrent with DORV, a 3 cm VSD, and pulmonary artery pressure exceeding systemic pressure. She underwent a Switch + VSD repair operation. For the remaining patients, the age at surgery ranged from 1 to 423 days (median 13 days), and the weight at surgery ranged from 2.25 to 8.00 kg (median 3.58 kg). While opinions on the optimal timing of ASO vary, most groups recommend performing the surgery as soon as possible within two weeks after birth. Delaying surgery by several days allows for the transition from fetal to neonatal circulation, reduces pulmonary vascular resistance, and supports the functional development of the newborn. However, low body weight remains a risk factor for death after major cardiac surgery in children. The mortality rates for patients aged less than 7 days and weighing less than 3 kg were significantly higher than those in the corresponding groups, identifying age and weight as important risk factors for postoperative death.
During surgery, the PFO of 57 patients was preserved to avoid surgery-related heart injury. In some patients with ASD, part of the defect was retained to maintain a small shunt of blood flow, which aids postoperative recovery, especially in cases where pulmonary circulatory resistance may fluctuate. Delayed sternal closure (DSC) was performed in 63 patients, a technique used to prevent heart compression in hemodynamically unstable states after pediatric heart surgery. The mean cardiopulmonary bypass (CPB) time and aortic clamp (AC) time during surgery were 135.9 ± 18.9 minutes and 81.2 ± 12.9 minutes, respectively. The CPB and AC times were significantly longer in patients with VSD or unconventional coronary artery patterns. The AC time was also longer in patients aged more than 14 days. The mean DSC time was 2.1 ± 1.5 days, with patients aged less than 7 days having significantly longer DSC times. Postoperatively, all patients were transferred to the ICU for close monitoring and underwent MV. The mean MV and ICU duration times were 103.0 ± 45.8 hours and 8.8 ± 3.3 days, respectively. Patients who required ICU care before surgery had significantly longer postoperative MV and ICU stays. The mean length of hospital stay (LOS) was 21.8 ± 7.0 days, with patients with VSD having significantly longer LOS. The LOS for the second child in the family was the shortest, with statistical significance.
Maternal-Fetal Environment and Prognosis
The overall physical characteristics of the child before surgery, such as premature birth, low weight, young age, preoperative requirement for MV and intensive care, or emergency surgery, were identified as the main factors affecting mortality at our center. These factors are closely related to the maternal-fetal environment (MFE). Damage to the MFE can lead to immature functions and abnormal development of multiple organ systems, decreasing biological reserves, increasing mortality rates after cardiac surgery, and prolonging LOS. MFE is considered impaired if one or more of the following conditions occur: gestational hypertension, preeclampsia, small for gestational age, or premature delivery. All nine patients who died had different impairments of the MFE, including premature birth, being one of a set of twins, being a test-tube baby, or maternal conditions such as obesity, hypertension, anemia, liver dysfunction, or thyroid problems during pregnancy. These conditions were rare among the surviving patients.
Conclusion
In summary, the number of patients at our center was small, and the mortality rate remains high. Clinicians should continue to promote prenatal diagnostics and provide sound advice to pregnant women. For those with serious problems and poor prognosis, selective induction of labor should be recommended to alleviate physical injury and financial burden. For those who continue the pregnancy, intensive perinatal monitoring is required to improve prognosis, and delivery at 39 to 40 weeks of gestation is recommended unless obstetric indications suggest otherwise. VSD and coronary artery patterns did not significantly affect surgery-associated mortality rates, while the overall physical characteristics of the patients before ASO were particularly important. If the baby is generally stable, delaying surgery to 14 days of age may reduce the mortality rate. Meanwhile, for children diagnosed 14 days or more after birth, ASO should be performed aggressively.
doi.org/10.1097/CM9.0000000000001738
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