Cardiac surgical strategy for extremely low-birthweight infants with pulmonary overcirculation

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1 Interactive CardioVascular and Thoracic Surgery 26 (2018) doi: /icvts/ivx417 Advance Access publication 9 January 2018 ORIGINAL ARTICLE Cite this article as: Kido T, Nishigaki K, Kawahira Y, Kagisaki K, Tanimoto K, Ehara E et al. Cardiac surgical strategy for extremely low-birthweight infants with pulmonary overcirculation. Interact CardioVasc Thorac Surg 2018;26: a b Cardiac surgical strategy for extremely low-birthweight infants with pulmonary overcirculation Takashi Kido a,kyoichinishigaki a, *, Yoichi Kawahira a, Koji Kagisaki a, Kazuki Tanimoto a, Eiji Ehara b and Yosuke Murakami b Department of Pediatric Cardiovascular Surgery, Osaka City General Hospital, Osaka, Japan Department of Pediatric Cardiology, Osaka City General Hospital, Osaka, Japan * Corresponding author. Department of Pediatric Cardiovascular Surgery, Osaka City General Hospital, Miyakojimadori, Miyakojimaku, Osaka, Japan. Tel: ; fax: ; kyo412355@gmail.com (K. Nishigaki). Received 22 September 2017; received in revised form 14 November 2017; accepted 2 December 2017 Abstract OBJECTIVES: This study aimed to review the clinical outcomes of staged cardiac surgery in extremely low-birthweight infants with congenital heart disease and pulmonary overcirculation. METHODS: Six extremely low-birthweight infants with congenital heart disease and pulmonary overcirculation underwent staged cardiac surgery between 2005 and The median birthweight was 895 g (range g), and the median gestational age was 28 weeks (range weeks). Clinical outcomes were evaluated, and we focused on pulmonary haemodynamics. RESULTS: Pulmonary artery banding or bilateral pulmonary artery banding was performed as the initial palliation at a median age of 23 days with a median body weight of 880 g. Corrective surgery was performed at a median age of 187 days with a median body weight of 3.9 kg. All of the patients successfully underwent corrective surgery and survived to date. Pulmonary hypertension regressed after corrective surgery in all of the patients, except for 1 patient with severe bronchopulmonary dysplasia. CONCLUSIONS: Acceptable outcomes can be obtained by staged cardiac surgery in extremely low-birthweight infants with congenital heart disease and pulmonary overcirculation. While early pulmonary artery banding can lead to regression of pulmonary hypertension after corrective surgery, close follow-up is required. Keywords: Extremely low-birthweight infant Congenital heart disease Pulmonary hypertension INTRODUCTION Low birthweight and prematurity are risk factors for mortality in surgery for congenital heart disease [1 4]. In particular, surgical repair for congenital heart disease in extremely low-birthweight (ELBW) infants (<1.0 kg) is a challenging issue. Several reports have shown acceptable outcomes of cardiac surgery in lowbirthweight infants, and early corrective surgery has been recommended [5 7]. However, most of the infants weighed >1.0 kg, and clinical outcomes of cardiac surgery in ELBW infants have not been well investigated. Pulmonary overcirculation and resultant pulmonary hypertension are frequently encountered in patients with congenital heart disease. The pulmonary vascular system is still developing in premature infants. Lung injury resulting from pulmonary overcirculation at this phase can lead to irreversible pulmonary vascular injury and unfavourable development of the pulmonary vascular system [8, 9]. In addition to pulmonary overcirculation, bronchopulmonary dysplasia, which frequently develops in premature infants, is associated with progression of pulmonary hypertension [10]. While pulmonary artery banding (PAB) might be a useful surgical palliation in premature infants with pulmonary overcirculation, whether pulmonary hypertension regresses after staged surgical repair is a matter of concern. This study aimed to investigate the clinical outcomes of staged cardiac surgery in ELBW infants with congenital heart disease and pulmonary overcirculation. MATERIALS AND METHODS Patients The institutional review board of the Osaka City General Hospital approved this retrospective study and waived the need for obtaining patient consent. Between January 2005 and May 2017, 350 ELBW infants were treated at our hospital. Among them, 6 patients had congenital heart disease and pulmonary overcirculation. The median VC The Author(s) Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

2 T. Kido et al. / Interactive CardioVascular and Thoracic Surgery 841 Table 1: Patient characteristics and operative data Patient no. Gender Birthweight Gestational weeks Primary diagnosis Associated diagnosis Initial palliation Body weight, Age (days) Corrective surgery Body weight, Age (days) 1 F VSD None PAB, PDA ligation F VSD None PAB, PDA ligation M VSD 21 trisomy PAB, PDA ligation Intestinal stenosis M TGA(II) West syndrome PAB, PDA ligation M Aortopulmonary Hydrocephalus Bilateral PAB window 6 F Coarctation of the aorta, VSD None Bilateral PAB F: female; M: male; PAB: pulmonary artery banding; PDA: patent ductus arteriosus; TGA: transposition of the great arteries; VSD: ventricular septal defect. birthweight was 895 g (range g), and the median gestational age was 28 weeks (range weeks). Thirty patients with isolated patent ductus arteriosus were excluded. Diagnoses of the 6 patients were ventricular septal defect (VSD) in 3 patients, transposition of the great arteries with VSD without left ventricular outflow obstruction [TGA(II)] in 1 patient, coarctation of the aorta with VSD in 1 patient and aortopulmonary window in 1 patient. Noncardiac malformations included digestive tract abnormality in 1 patient, West syndrome in 1 patient and hydrocephalus in 1 patient. Chromosomal abnormality was observed in 1 patient with trisomy 21. Operative data All patients underwent a palliative procedure including PAB and bilateral PAB prior to corrective surgery at the median age of 23 days (range 9 64 days) with the median body weight of 880 g (range g). PAB through a median sternotomy was performed using a silk suture with a circumference of mm in 3 patients with VSD and in 1 patient with TGA(II). Adequate tightening of the band was determined if systemic arterial pressure was increased by 5 10 mmhg and arterial oxygen saturation was maintained at greater than 90% in patients with VSD and at 75% in the patient with TGA(II) on 40% of inspired oxygen. Pulmonary artery pressure was not monitored during the operation. Ligation of the patent ductus arteriosus was concomitantly performed. Bilateral PAB with a circumference of 9 mm in each pulmonary artery using silk sutures was performed in 1 patient with aortopulmonary window and in 1 patient with coarctation of the aorta. The circumference of 9 mm in each pulmonary artery was determined according to our institutional preference [11]. Ductal patency was maintained with prostaglandin E1 infusion in both patients. The timing of bilateral PAB in these 2 patients was late, at 64 and 32 days after birth, respectively, because they were transferred to our hospital at 63 and 29 days. Corrective surgery was performed at a median age of 187 days (range days) with a median body weight of 3.9 kg (range kg). All corrective surgeries were performed through a median sternotomy using cardiopulmonary bypass with moderate hypothermia and cardiac arrest using aortic crossclamping. At corrective surgery, enlargement of the pulmonary artery was not required after pulmonary artery debanding in all patients. The patient demographics and operative data are listed in Table 1. Data collection and analysis Perioperative data were obtained through a retrospective review of hospital records. In 4 patients who underwent PAB as the initial palliation (Patients 1 4), the pressure gradient through PAB was evaluated using echocardiography within 1 week, 3 months and 6 months after the operation. Cardiac catheterization was performed at the median period of 17 days (10 20 days) before corrective surgery. Mean pulmonary artery pressure and pulmonary artery resistance were evaluated in 3 patients with VSD. In a patient with TGA(II), only the mean pulmonary artery pressure was evaluated because pulmonary artery resistance could not be accurately calculated. The severity of bronchopulmonary dysplasia was assessed with computed tomography [12] at the median period of 15 days (6 35 days) before corrective surgery in all patients, except for Patient 3. The maximum tricuspid regurgitation pressure gradient was measured with the last echocardiography taken, which was conducted at a median period of 13.5 months ( months) after corrective surgery. In 4 patients with VSD and trisomy 21, TGA(II), aortopulmonary window and coarctation of the aorta with VSD (Patients 3 6), the main pulmonary artery pressure and pulmonary artery resistance were evaluated with cardiac catheterization at the median period of 16 months (15 46 months) after corrective surgery. RESULTS Overall outcomes Follow-up was completed in all patients with a median follow-up period after birth of 5.5 years (range years). All patients achieved corrective surgery and survived to date. All of the survivors were followed up at the outpatient clinic with oral feeding and CONGENITAL

3 842 T. Kido et al. / Interactive CardioVascular and Thoracic Surgery Table 2: Outcomes of patients who underwent PAB Patient no. PAB Within 1 week At 6 months Before corrective surgery After corrective surgery Circumference (mm) PG Weight PG Weight mpap PAR (U) TRPG (on O 2 ) (21) (22) mpap: mean pulmonary artery pressure; PG: pressure gradient; PAB: pulmonary artery banding; PAR: pulmonary artery resistance; TRPG: tricuspid regurgitation pressure gradient. Figure.1: Chest computed tomographic findings before corrective surgery in Patient 2 with bronchopulmonary dysplasia. (A) Intercostal bulging suggesting pulmonary overexpansion into the intercostal space (open arrowhead). (B) Emphysematous change with bullae and blebs (open arrow). (C) Triangular subpleural opacities are shown as an external base and internal apex involvement (open arrow). spontaneous breathing without tracheostomy. The present standard deviation (SD) score of body weight was a median of -2.6 (range -4.9 to -1.1). Morbidity Intestinal perforation caused by congenital jejunal stenosis developed in Patient 3 with VSD. Emergent intra-abdominal irrigation and retrieval of jejunal stenosis were performed at the age of 3 months in this patient. Intraventricular haemorrhage was identified soon after birth in Patient 5 with aortopulmonary window. In this patient, intraventricular drainage was performed at the age of 35 days, followed by placement of an Ommaya reservoir at the age of 2 months. Pulmonary haemodynamics Oxygen therapy was initiated after PAB and is still continuing in Patient 2 with severe bronchopulmonary dysplasia and in Patient 3 with trisomy 21. Administration of a pulmonary vasodilator was indicated after corrective surgery in Patient 2. In 4 patients who underwent PAB (Patients 1 4), the pressure gradient through PAB was 26.3 ± 12.6 mmhg (mean ± SD) within 1 week after the operation, 59.9 ± 18.4 mmhg at 3 months after the operation and 58.3 ± 15.3 mmhg at 6 months after the operation. Cardiac catheterization before corrective surgery showed a mean pulmonary artery pressure of 19.8 ± 8.0 mmhg and pulmonary artery resistance of 4.5 ± 3.5 U. Recent echocardiography showed that the maximum tricuspid regurgitation pressure gradient 28 ± 18 mmhg ( mmhg), which suggested that pulmonary hypertension regressed in all patients, except for Patient 2. In 2 patients with oxygen therapy (Patients 2 and 3), a decrease in the tricuspid regurgitation pressure gradient was confirmed with oxygen inhalation. The results of echocardiography and cardiac catheterization in patients who underwent PAB are shown in Table 2. Regression of pulmonary hypertension was also confirmed with cardiac catheterization in 4 patients with VSD and trisomy 21, TGA(II), aortopulmonary window and coarctation of the aorta with VSD (Patients 3 6). Cardiac catheterization after corrective surgery in these patients (Patients 3 6) showed that the mean pulmonary artery pressure was 19, 12, 17 and 16 mmhg and pulmonary artery resistance was 3.8, 1.3, 4.9 and 2.7 U, respectively. Computed tomography before corrective surgery showed typical abnormalities of bronchopulmonary dysplasia, including hyperexpansion, emphysema and fibrous/ interstitial abnormalities in Patient 2 (Fig. 1A C). DISCUSSION This study investigated the clinical outcomes of staged cardiac surgery in ELBW infants with pulmonary overcirculation. We found that all patients successfully achieved corrective surgery. Pulmonary hypertension regressed after corrective surgery in all patients, except for 1 patient with severe bronchopulmonary dysplasia.

4 T. Kido et al. / Interactive CardioVascular and Thoracic Surgery 843 Despite technological advances and efforts of child health experts during the last generation, ELBW infants remain at high risk for death and disability with 30 50% mortality [13]. Kato et al. [14] reported successful staged management in 4 ELBW infants with congenital heart disease and pulmonary overcirculation. However, the rate of survival to discharge was reported as 56% in ELBW infants with congenital heart disease in a multi-institutional study [15]. Our results might be acceptable based on these previous studies, but management of severe comorbidities, such as intestinal perforation and intraventricular haemorrhage, remains a challenging issue. Some reports have shown favourable outcomes for early corrective surgery in low-birthweight patients with congenital heart disease [4 6], but most of the infants weighed >1.0 kg. Low body weight at cardiac surgery has been reported as a risk factor for high operative mortality in patients with congenital heart disease [1, 2, 4]. Therefore, coping with open-heart surgery in patients weighing <1.0 kg with excessive pulmonary flow might be difficult. Consequently, staged cardiac surgery, as reported in this study, is reasonable in this patient population. The timing of PAB or bilateral PAB in ELBW infants is a matter of concern. Considering the rapid decrease in pulmonary vascular resistance after birth, these procedures should be performed after at least 1 week of age, and further waiting may result in deleterious effects on the pulmonary vascular system. Moreover, waiting for longer than 1 month without PAB or bilateral PAB may not result in a significant weight gain as shown in our cohort. However, a delayed decrease in pulmonary vascular resistance in patients with bronchopulmonary dysplasia or trisomy 21 should be taken into account when determining the timing of these procedures. Whether pulmonary hypertension regresses after corrective surgery is a concerning issue in ELBW infants with congenital heart disease and pulmonary overcirculation. The entire bronchopulmonary tree is established by 18 weeks. The distal pulmonary circulation actively develops by 20 weeks, which closely approximates the gestational age of ELBW infants. Injury at this phase predisposes the infant to irreversible pulmonary vascular injury and delayed or arrested growth of alveoli [8, 9, 15]. As well as pulmonary overcirculation, bronchopulmonary dysplasia also worsens pulmonary haemodynamics [10]. This study showed regression of pulmonary hypertension in 5 of 6 patients by performing PAB or bilateral PAB at the median age of 23 days. However, close follow-up is required because the causes of abnormality in the pulmonary circulation are multifactorial, and some patients still showed high pulmonary artery resistance. The optimal degree of PAB was reported in patients who weighed <_2 kg [16] and<_3 kg [17]. However, the adequate circumference of PAB in ELBW infants remains unclear. Although this study showed an acceptable increase in the pressure gradient after PAB without readjustment, further studies are required. The adequate circumference of bilateral PAB is also unclear in ELBW infants. We previously reported successful bilateral PAB with a circumference of 9 mm in 2 cases of coarctation or interruption of the aorta who weighed <1.0 kg [11]. Our experience suggests that a circumference <8 mm appears to be difficult for precisely controlling the diameter of small pulmonary arteries in ELBW infants, and there is danger of complete obstruction of the arteries. The validity of bilateral PAB with a circumference of 9 mm in ELBW infants was confirmed in this study. Limitations This has several limitations. First, this was a retrospective study, which consisted of a limited number of patients and the follow-up period was short for some patients. Second, cardiac catheterization was performed after corrective surgery in only 4 of 6 patients. Therefore, whether pulmonary hypertension regressed was not accurately evaluated. CONCLUSION Acceptable outcomes can be obtained by staged cardiac surgery in ELBW infants with congenital heart disease and pulmonary overcirculation. Early PAB or bilateral PAB can lead to regression of pulmonary hypertension after corrective surgery. However, the causes of worsening pulmonary haemodynamics are multifactorial. Close follow-up is required. ACKNOWLEDGMENTS We thank Ellen Knapp from Edanz Group ( ac) for editing a draft of this manuscript. Conflict of interest: none declared. 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