Interact CardioVasc Thorac Surg 2008;7:328-330. doi:10.1510/icvts.2007.164806
© 2008 European Association of Cardio-Thoracic Surgery
Pulmonary artery growth after Norwood and bidirectional Glenn procedure
Shin Takabayashia,*,
Yoshihide Mitanib,
Kazuto Yokoyamaa and
Hideto Shimpoa
a Department of Thoracic and Cardiovascular Surgery, Mie University Graduate School of Medicine, 2-174, Edobashi, Tsu, Mie 514-8507, Japan
b Department of Pediatrics, Mie University Graduate School of Medicine, 2-174, Edobashi, Tsu, Mie 514-8507, Japan
Received 10 August 2007;
received in revised form 19 November 2007;
accepted 21 November 2007
*Corresponding author. Tel.: +81-59232-1111, (5503); fax: +81-59231-5145.
E-mail address: shin1111{at}clin.medic.mie-u.ac.jp (S. Takabayashi).
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Abstract
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A 19-day-old boy diagnosed with hypoplastic left heart syndrome underwent stage I bilateral pulmonary artery banding and main pulmonary artery-to-descending aorta shunt. A restrictive atrial septal defect existing before stage I recurred after balloon atrioseptostomy. After stage II Norwood and bidirectional Glenn procedure at age nine months, the Nakata index decreased to 73 mm2/m2 (pulmonary artery mean pressure: 15 mmHg) and multiple systemic venous collaterals developed. Thus, we instituted oral sildenafil medication, and undertook surgical chest subcutaneous venous ligation and coil embolizations. Three years later, the Nakata index had increased to 117 mm2/m2 (pulmonary artery mean pressure: 13 mmHg) and a Fontan procedure was successfully performed.
Key Words: Hypoplastic left heart syndrome; Restrictive atrial septal defect; Pulmonary artery growth; Bilateral pulmonary artery banding; Norwood and bidirectional Glenn procedure
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1. Introduction
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In hypoplastic left heart syndrome (HLHS), restrictive atrial septal defect (ASD) induces abnormal pulmonary artery (PA) vasculature [1] that can elevate PA resistance [2]. Consequently, the significant transpulmonary gradient caused by elevated pulmonary vascular resistance (PVR) adversely effects hemodynamics after a bidirectional Glenn (BDG) procedure. We report our experience of PA growth and reduction of severe systemic venous collaterals after a stage II Norwood and BDG procedure in a HLHS patient managed through stage I bilateral PA banding.
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2. Case report
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A 19-day-old boy, weighing 2.6 kg was diagnosed with HLHS (aortic atresia and mitral stenosis, ascending aorta; 2 mm diameter) with mild tricuspid regurgitation, restrictive ASD and dilated left atrium by echocardiography. Prostaglandin E1 was administrated before stage I palliation. The ASD was preoperatively enlarged to 6.1 mm on echocardiography by balloon atrioseptostomy.
We performed a stage I bilateral PA banding (both circumferences; 14 mm, using a 2 mm width and 0.4 mm thickness ePTFE strip), and main PA-to-descending aorta shunt with a 6 mm ePTFE conduit (adaptable for future somatic growth) through a left thoracotomy. The SpO2 decreased from 88 to 82% in room air during stage I, and prostaglandin E1 administration was stopped immediately after stage I. After discharge at age eight months, hypoxia progressed (SpO2: 68%) and the ASD diminished to 1.8 mm. On cardiac catheterization, right PA mean pressure was 38 mmHg (the left could not be measured) and Nakata index 746 mm2/m2. The pressure gradients of the right and left PA banding sites by echocardiography were 45 and 40 mmHg, respectively.
We performed an emergency operation to enlarge the very small ASD. The right PA mean pressure decreased to 11 mmHg on intraoperative pressure study. Postoperative echocardiography revealed the pressure gradients of the right and left PA banding sites were 66 and 56 mmHg, respectively. Although tricuspid regurgitation increased to a moderate degree on echocardiography, there was no coronary ischemic event.
At age nine months, weight 4.5 kg, we performed stage II palliation; Norwood procedure and bidirectional Glenn (BDG) with azygos venous division, and tricuspid De Vega annuloplasty through a median sternotomy using cardiopulmonary bypass without circulatory arrest [3]. The PA bands had not migrated and were removed at stage II. Despite there being no prostaglandin E1 administration, the ductus arteriosus was narrow but patent until stage II. Immediately after the operation, the postoperative mean superior vena caval pressure was 20 mmHg and SpO2 70%; however, these improved within a week.
At six months after stage II, although PA mean pressure decreased to 15 mmHg by cardiac catheterization, multiple severe systemic venous collaterals from the upper to lower extremities had developed (Fig. 1). Despite no PA plication at stage II, the Nakata index considerably decreased to 73 mm2/m2 (Fig. 2a). We next performed fifteen double ligations of multiple dilated subcutaneous chest veins using 5-0 polypropylene suture lines under general anesthesia. During the operation, mean PA pressure increased from 13 to 18 mmHg and SpO2 from 70 to 75%. We initiated oral sildenafil medication (maximum: 1.4 mg/kg/day) to reduce the PVR. We placed several coil embolizations for systemic venous collaterals. At age four years and one month, the PA had grown (Nakata index: 117 mm2/m2, Fig. 2b) and the systemic venous collaterals reduced. PA mean pressure was 13 mmHg by cardiac catheterization (SpO2 83%). There were no side effects from the sildenafil medication.
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Fig. 1. Systemic venous collaterals. (a) A large intrathoracic venous collateral developed. (b) Dilated chest subcutaneous veins.
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At age four years and four months, weight 14.0 kg, we performed an extracardiac total cavopulmonary connection. The patient is alive and well one year after Fontan completion. SpO2 increased to 98% and PA mean pressure was 15 mmHg by cardiac catheterization.
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3. Discussion
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HLHS with restrictive ASD has a higher mortality than non-restrictive [2]. Histological analysis of lung in HLHS with restrictive ASD shows abnormal PA vasculature [1, 4]. Although the Nakata index, a method for quantitative standardization of the cross-sectional area of the PA [5], before stage II was 746 mm2/m2 in our patient, it decreased to 73 mm2/m2, an unusual course. One possible reason is that an excessive PA flow caused by the large circumference of the stage I bilateral PA banding was present after stage I. As well, vascular changes caused by restrictive ASD would have remained after stage II. The high PVR resulting would have induced a small PA and the systemic venous collaterals [6]. Another possible reason is that pulmonary flow was supplied by pulsatile pressure even if bilateral PA banding was performed. After the BDG procedure, where PA flow is supplied by continuous systemic venous flow, it is difficult to grow the PA [7]. Therefore, for hypoplastic PA and systemic venous collaterals, we undertook a combined therapy of pulmonary vasodilation [8, 9] and reduction of the collateral flow. This should more effectively grow the PA than a single therapy.
After our experiences with this patient, we altered our ASD management to repetitive balloon atrioseptostomy until stage II and now perform stage II at three or fourmonths of age to avoid the progression of restrictive ASD. For stage I bilateral PA banding, we now think the ideal circumference is around 10 mm (9–10 mm for 2.5–3.0 kg and 10–11 mm for 3.0–3.5 kg patients). Although patients must be kept on prostaglandin E1 administration until stage II, systemic flow maintenance by prostaglandin E1 [10], that naturally forms a ductus arteriosus without iatrogenic complications, is better than by main PA-to-descending aorta shunt or ductal stent. However, a main PA-to-descending aorta shunt could be an option for systemic flow maintenance when the ductus is stenotic.
Until there is surgical ASD enlargement, careful follow-up for ASD opening is necessary in HLHS patients managed through stage I bilateral PA banding. For hypoplastic PA and systemic venous collaterals after stage II Norwood and BDG procedure, we performed a Fontan completion after combined treatment consisted of oral sildenafil to decrease PVR and reduction of the collateral flow.
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References
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Abstract
1. Introduction