Eur J Cardiothorac Surg 2006;29:100-104
© 2006 Elsevier Science NL
Surgical strategy for pulmonary coarctation in the univentricular heart
Hyun Koo Kim
b
,
Woong-Han Kim
a
,
*
,
Soo-Cheol Kim
b
,
Cheong Lim
a
,
Chang Ha Lee
b
,
Soo-Jin Kim
b
a Department of Thoracic and Cardiovascular Surgery, Clinical Research Institute, Seoul National University Children's Hospital, College of Medicine, Seoul National University, 28 Yongon-Dong, Jongno-Gu, Seoul 110-744, Korea
b Department of Thoracic and Cardiovascular Surgery, Pediatrics, Sejong General Hospital, Sejong Heart Institute, Bucheon, Korea
Received 21 July 2005;
received in revised form 17 October 2005;
accepted 19 October 2005.
* Corresponding author. Tel.: +82 2 2072 3637; fax: +82 2 3672 3637. (Email: woonghan{at}snu.ac.kr).
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Abstract
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Objective: The placement of a modified Blalock–Taussig shunt in patients suffering from pulmonary coarctation can result in the aggravation of uneven pulmonary blood flow. This may subsequently obviate the possibility of future performance of the Fontan procedure. The objective of this study was to evaluate mid-term results in patients with pulmonary coarctation who had undergone the placement of a modified Blalock–Taussig shunt, coupled with a pulmonary artery angioplasty. Methods: We retrospectively reviewed the records of 13 patients who had undergone the placement of a modified Blalock–Taussig shunt, coupled with concomitant pulmonary angioplasty, between September 1998 and August 2002. All patients received follow-up angiographic evaluations. Results: On the ipsilateral side of the modified Blalock–Taussig shunt, we observed a significant increase in the pulmonary artery index during a mean follow-up period of 11 ± 5 months (preoperative 82 ± 37 mm2/m2, follow-up 129 ± 57, p
= 0.03). On the contralateral side, we also observed a significant increase in the pulmonary artery index (preoperative 90 ± 56 mm2/m2, follow-up 137 ± 56, p
= 0.047). There was one late death. During the follow-up period (mean 23 ± 18 months), 10 patients received either a bidirectional or total cavopulmonary shunt and five of these patients underwent extracardiac Fontan operations. Conclusions: Our study demonstrated that the placement of a modified Blalock–Taussig shunt, with concomitant pulmonary artery angioplasty, constitutes a good initial surgical strategy in cases of univentricular heart with pulmonary coarctation.
Abbreviations: AV valve = atrioventricular valve • BCPA = bidirectional cavopulmonary anastomosis • D–K–S procedures = Damus–Kaye–Stansel procedures • MBTS = modified Blalock–Taussig shunt • PA = pulmonary artery • PAI = pulmonary artery index • PDA = patent ductus arteriosus • PTFE = polytetrafluoroethylene • Rp = pulmonary vascular resistance • TAPVD = total anomalous pulmonary venous drainage • TCPA = total cavopulmonary anastomosis • WU = Wood Unit
Key Words: Congenital heart disease • Univentricular heart • Fontan procedure • Pulmonary arteries • Angiography
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1. Introduction
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Pulmonary artery stenosis at the site of a patent ductus arteriosus (PDA) is referred to as pulmonary coarctation; this condition is observed in 60% or more of patients with pulmonary atresia and in 10% or more of patients with pulmonary artery stenosis [1]. Pulmonary coarctation is characterized by the differential growth of PDA tissues and the normal pulmonary artery tissues during pulmonary artery growth and by a gradual aggravation of the pulmonary artery stenosis [2].
In neonates and children with critically diminished pulmonary blood flow, palliative systemic-pulmonary artery shunt procedures remain key strategies in the overall modality of treatment. The modified Blalock–Taussig shunt (MBTS) is currently widely used; shunt flow can be regulated in accord with the size of the systemic artery [3]. However, the incidence of iatrogenic pulmonary artery deformation subsequent to MBTS has been reported to be between 35% and 65% [4]. In particular, the placement of the MBTS in young patients suffering from pulmonary coarctation can result in the exacerbation of unequal flow between the right and left pulmonary arteries; in addition, it increases the risks of kinking, stenosis and deformation as well as the possibility of complete occlusion of the shunts at the distal anastomosis as the child grows. Consequently, subsequent Fontan procedures may be rendered difficult or impossible [5]. A strategy involving simultaneous MBTS and pulmonary artery angioplasty has, however, been reported to yield highly satisfactory early postoperative results; in addition, patients appear to tolerate subsequent procedures as required [6]. The objective of this study was to evaluate the clinical role and mid-term results of pulmonary artery growth in patients with pulmonary coarctation who had undergone the placement of an MBTS coupled with a simultaneous pulmonary artery angioplasty.
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2. Materials and methods
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We retrospectively reviewed the findings of 13 patients, who suffered from the development of a univentricular heart with pulmonary atresia (or severe pulmonary stenosis) and pulmonary coarctation; these patients had a MBTS and pulmonary artery angioplasty between September 1998 and August 2002. In most patients, the pulmonary coarctation was diagnosed by echocardiography. If the echocardiographic view was suspicious for the diagnosis of pulmonary coarctation, a chest CT scan was used for definite diagnosis. In this study, 8 of the 13 patients had the chest CT scan just before the shunt procedure. All procedures were performed by one surgeon (W.H. Kim).
2.1 Surgical technique
A median sternotomy incision was made and the pulmonary artery and innominate and subclavian arteries were dissected. The MBTS was constructed with a polytetrafluoroethylene (PTFE) graft, which was interposed between the innominate or subclavian arteries and the ipsilateral pulmonary artery at the opposite side of the PDA. The size of the graft was selected by the operating surgeons on the basis of body weight and the size of the pulmonary and subclavian arteries. All anastomoses were performed with 7-0 or 8-0 synthetic monofilament suture material. The PDA was then divided (Fig. 1
) and pulmonary artery angioplasty was performed. The material used for pulmonary artery angioplasty was the main pulmonary artery stump, if it was available this was the first choice for the flap (Fig. 2
). If not, fixed autopericardium was used for neonates or early infants and bovine pericardium or a Gore-tex patch was used for late infants. All patients received anti-platelet agents after the operation.
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Fig. 1. Pulmonary coarctation is shown with divided patent ductus arteriosus (arrow). LPA: left pulmonary artery; PDA: patent ductus arteriosus.
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2.2 Pulmonary artery size measurement
In all 13 patients, pulmonary artery size was preoperatively measured via echocardiography, and subsequently by angiography, immediately prior to the placement of a bidirectional or total cavopulmonary anastomosis (BCPA or TCPA). The size of the bilateral pulmonary artery before the upper branch bifurcation was measured for calculating the Nakata index. Pulmonary artery growth was then evaluated using the pulmonary artery index (PAI) measurements advocated by Nakata et al. [7]. In this study, we assessed the ipsilateral and contralateral sides of the MBTS, or the right and left PAI, in order to determine the extent of postoperative changes in pulmonary artery size.
2.3 Patient data
The mean age (±standard deviation) was 123 ± 113 days (median 50 days, range 14–375 days), and 7 out of the 13 patients (53.8%) were less than 90 days of age. The mean body weight was 5 ± 1.7 kg (median 4.5 kg, range 3.3–8.7 kg). In two patients who underwent the coarctoplasty and pulmonary artery banding initially (patients 7 and 11), severe pulmonary coarctation and subaortic stenosis developed, which increased pulmonary resistance. These patients then underwent the Damus–Kaye–Stansel (D–K–S) procedure and MBTS with pulmonary angioplasty at same time. Detailed diagnoses of such cases are listed in Table 1
.
2.4 Statistical analysis
Statistical analysis of the data was performed with the STATISTICA 6.0 software (StatSoft Inc., 2003 East 14th Street Tulsa, OK 74104, USA). Data were expressed as mean ± standard deviation and as medians and ranges. The Wilcoxon signed-rank test was used in the statistical analysis of the data and p-values less than 0.05 were considered to be significant.
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3. Results
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MBTS were placed on the right side in nine patients, and on the left side in four. The size of the PTFE graft used in MBTS was 3 mm in one patient, 3.5 mm in six, 4 mm in four, and 5 mm in two. The pulmonary artery angioplasty was performed on the same side as the pulmonary artery stenosis in 11 patients and bilaterally in two. The materials used for the pulmonary artery angioplasty were the main PA flap in five patients, the fixed autologous pericardium in five, bovine pericardium in two, and a PTFE patch in one (Table 2
). In nine patients, the procedure was done with the cardiopulmonary bypass (CPB) and in four a cardioplegic solution was added for performing the D–K–S procedures (patients 7 and 11) and repair of the total anomalous pulmonary venous drainage (TAPVD) (patients 3 and 8). In five patients, CPB was used for PA patch angioplasty.
3.1 Postoperative course
The mean duration during which the mechanical ventilator was used was 3.5 ± 2.6 days (median 3 days, range 1–11 days). The mean duration of the ICU stay was 13.5 ± 12.3 days (median 9 days, range 4–47 days).
Only one patient developed pulmonary artery stenosis at the previous angioplasty site. In this patient, we performed a redo-pulmonary artery angioplasty with a PTFE patch (patient 5). One patient had undergone subsequent BCPA and a common atrioventricular (AV) valve replacement due to progressive common AV valvular regurgitation detected 16 months after the initial operation (patient 11). After this operation, the patient died suddenly, 4 months later, of unknown causes. In the present study, we observed no early mortality, however, there was one late death, corresponding to an overall 7.7% mortality rate (follow-up from 8 to 52 months, mean 23 ± 18 months).
3.2 Pulmonary artery size
The follow-up angiograms were performed before subsequent BCPA or TCPA operations, 11 ± 5 months (median 9.7 months, range 5.3–180 months) after the placement of the MBTS in all patients. We compared the size of the right and left pulmonary arteries in order to determine whether the ipsilateral and contralateral sides of the MBTS had grown evenly after the placement of the MBTS and the pulmonary artery angioplasty. On the ipsilateral side, we detected a significant increase in PAI during the follow-up period (preoperative PAI 82 ± 37 mm2/m2, follow-up PAI 129 ± 57, p
= 0.03). On the contralateral side, we noticed a significant increase in PAI during the follow-up period (preoperative PAI 90 ± 56 mm2/m2, follow-up PAI 137 ± 56, p
= 0.047) (Fig. 3 ). Right and left PAI also showed significant increases during the follow-up period (right side: preoperative PAI 83 ± 31 mm2/m2, follow-up PAI 130 ± 63, p
= 0.02; left side: preoperative PAI 89 ± 59 mm2/m2, follow-up PAI 136 ± 51, p
= 0.04). Total PAI revealed a more significant amount of increase than did preoperative PAI (preoperative PAI 173 ± 77 mm2/m2, follow-up PAI 266 ± 109, p
= 0.02) (Fig. 4
). Mean pulmonary artery pressure was measured to be 13 ± 3 mmHg (median 14 mmHg, range 8–17 mmHg), the mean pulmonary vascular resistance (Rp) 1.7 ± 0.6 Wood Unit (WU) (mean 1.8 WU, range 0.9–2.4 WU), and the mean central venous pressure 7.4 ± 2.6 mmHg (median 8.2 mmHg, range 4–11 mmHg).
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Fig. 3. Changes in ipsilateral and contralateral Nakata indices compared preoperatively and before subsequent procedure. CPAI: contralateral pulmonary artery index; CPS: cavopulmonary anastomosis; IPAI: ipsilateral pulmonary artery index; PAI: pulmonary artery index.
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Fig. 4. Changes in right and left Nakata indices compared preoperatively and before subsequent procedure. CPS: cavopulmonary anastomosis; LPAI: left pulmonary artery index; PAI: pulmonary artery index; RPAI: right pulmonary artery index.
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3.3 Subsequent operations
Twelve patients received BCPA or TCPA (Kawashima operation) operations. Five of these patients also underwent extracardiac Fontan operations, 24 ± 11 months (median 24.5 months, range 14.1–41.2 months) after BCPA or TCPA (Table 3
). All of these operations were successfully performed and were associated with uneventful postoperative courses. One patient developed diffuse pulmonary vein stenosis after previous TAPVD repair and proved unable to progress with regard to staging toward the conditions required for a successful Fontan procedure (patient 8).
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4. Discussion
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Well-balanced pulmonary blood flow and cardiac function are key factors for a successful outcome after the Fontan operation [8]. Unfortunately, some patients cannot undergo a Fontan operation because they do not fulfill requirements for this surgery. In particular, patients suffering from pulmonary coarctation are likely to manifest uneven pulmonary blood flow and compliance [9], or to have pulmonary arterial discontinuities [10]. Therefore, when a Fontan type approach is planned, the early restoration of even and unobstructed blood flow in both pulmonary arteries is critical [10].
Palliative systemic to pulmonary shunts result in the augmentation of tissue oxygenation and promote development of the PA [9]. However, the MBTS can sometimes induce distortion and stenosis of the pulmonary artery; this may have important implications for future Fontan procedures in patients with a univentricular heart [5]. In particular, the placement of the MBTS in patients suffering from pulmonary coarctation can result in the exacerbation of unequal blood flow between the right and left pulmonary arteries, which may preclude subsequent Fontan procedures [5].
Pulmonary artery growth depends on latent growth ability, which appears to be more significant in patients less than 1 year of age than in those who are more than a year old. Therefore, it is desirable to perform the palliative shunt operation in patients less than 1 year in order to ensure sufficient and bilateral pulmonary arterial growth [11].
The catheterization is not necessary in order to diagnose the pulmonary coarctation. The echocardiography is sufficient for diagnosis or suspicion of a pulmonary coarctation. A chest CT scan can make a definite diagnosis if the echocardiographic finding is suspicious. In this study, 8 of the 13 patients had a chest CT scan.
In the present study, 9 of the 13 patients (69.2%) had the diagnosis of heterotaxy syndrome. Therefore, careful evaluation for a potential pulmonary coarctation may be necessary for these patients.
Before 1998, the authors had experienced that the uneven pulmonary blood flow caused poor results in patients exhibiting pulmonary coarctation. Therefore, we have advocated concomitant MBTS and PA angioplasty in patients with pulmonary atresia (or severe pulmonary stenosis) with pulmonary coarctation. We found that this concomitant procedure, when performed prior to subsequent BCPA, might increase the PAI values sufficiently to render these patients good candidates for the Fontan procedure. Moreover, the size of both pulmonary arteries tends to increase evenly when these combined procedures are performed; this will ensure the maintenance of even pulmonary blood flow bilaterally.
The results of this study clearly demonstrate that this concomitant procedure is well tolerated in patients and facilitates subsequent procedures via the assurance of equal pulmonary blood flow.
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Abstract
1. Introduction
