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a Department of Cardiac Surgery, Children's Hospital Boston, Boston, Massachusetts
b Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts
c Department of Surgery, Harvard Medical School, Boston, Massachusetts
d Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
Accepted for publication June 22, 2009.
* Address correspondence to Dr Bacha, Department of Cardiac Surgery, Children's Hospital Boston, Bader 273, 300 Longwood Ave, Boston, MA 02115 (Email: emile.bacha{at}cardio.chboston.org).
| Dr Thiagarajan discloses that he has a financial relationship with the Seattle Children's Hospital.
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| Abstract |
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Methods: A retrospective review of the ECMO database at Children's Hospital Boston was undertaken. Children with unrepaired congenital heart disease supported with ECMO for acute cardiac or respiratory failure as bridge to a definitive or palliative cardiac surgical procedure were identified. Data collection included patient demographics, indication for ECMO, details regarding ECMO course and complications, and survival to hospital discharge.
Results: Twenty-six patients (18 male, 8 female) with congenital heart disease were bridged to surgical palliation or anatomic repair with ECMO. Median age and weight at ECMO cannulation were, respectively, 0.12 months (range, 0 to 193) and 4 kg (range, 1.8 to 67 kg). Sixteen patients (62%) survived to hospital discharge. Variables associated with mortality included inability to decannulate from ECMO after surgery (p = 0.02) and longer total duration of ECMO (p = 0.02). No difference in outcomes was found between patients with single and biventricular anatomy.
Conclusions: Extracorporeal membrane oxygenation, used as a bridge to surgery, represents a useful modality to rescue patients with failing circulation and unrepaired complex heart defects.
| This article has been selected for the open discussion forum on the CTSNet Web Site: http://www.ctsnet.org/sections/newsandviews/discussions/index.html
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Extracorporeal membrane oxygenation (ECMO) provides excellent cardiopulmonary support for children with refractory postoperative cardiopulmonary failure [1–4] after repair of congenital heart defects, and it has also been shown to successfully bridge some of these children to heart transplantation [5–7]. Support of failing cardiorespiratory function in patients with unrepaired congenital heart disease (CHD) remains a challenging clinical scenario. Reports of ECMO support as a preoperative bridge to a surgical procedure in children with CHD are lacking and restricted to small series of patients or case reports [8, 9].
The goal of this study is to report on survival to hospital discharge of children with CHD who require preoperative ECMO support from a single institution and to evaluate preoperative, procedural, and ECMO support-related factors associated with mortality. We hypothesized that some children with CHD requiring preoperative ECMO for refractory cardiopulmonary failure can be successfully supported, stabilized, and bridged to reparative or palliative cardiac surgery.
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| Results |
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Surgical Management
The most common procedure in our series was an arterial switch operation for D-transposition of the great arteries in 8 patients, followed by staged palliation of single-ventricle lesions including hypoplastic left heart syndrome (HLHS) and other anatomic variants: Norwood operation (n = 3); bidirectional Glenn (n = 3); aortopulmonary shunt (n = 1); and bilateral pulmonary artery bands (n = 1). Bilateral pulmonary artery bands were performed on a newborn with HLHS (aortic atresia/mitral stenosis variant), left ventricular–coronary fistulas, and extensive cystic adenoid malformation of the lung. Details of other cardiac surgical procedures in this study population are listed in Table 2. All patients in the D-transposition of the great arteries group had a balloon atrial septestomy before operation. Adequacy of the balloon atrial septestomy (unrestrictive atrial septal defect with left to right shunt) was confirmed by echocardiogram. Sixteen patients (61.5%) did not require ECMO support after surgery, and there were 3 deaths in this group. Decannulation in the operating room was based on patient hemodynamics, oxygenation, and inotropic support required soon after weaning off cardiopulmonary bypass. Of 10 patients who could not be decannulated immediately after surgery, 7 died. Weaning and decannulation from ECMO were undertaken after recovery of hemodynamics and respiratory function. Median time on ECMO before repair was 3 days (range, 0 to 13), and total median duration of ECMO support was 6 days (range, 0 to 27). Specific pre-ECMO and on-ECMO surgical procedures as well as anatomic diagnoses and outcomes are also shown in Table 2.
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Outcomes
Sixteen patients (62%) survived to hospital discharge. All hospital survivors are alive at a median follow-up of 4 years (range, 2 months to 12 years). Patients who were unable to be decannulated from ECMO at the end of their operation were more likely to die compared with patients who were (70% versus 19%, p = 0.02). A long ECMO run (median 8 days for nonsurvivors versus 4 days for survivors) was also associated with mortality (p = 0.02). Mortality among neonates was 47% (8 of 17). Both patients weighing less than 2 kg died. The 3 patients with HLHS who underwent a stage I (Norwood [n = 2], bilateral pulmonary artery band [n = 1]) died, whereas 1 patient with tricuspid atresia who underwent a Norwood operation survived. The ECMO features and outcomes between survivors and nonsurvivors are compared in Tables 3 and 4.
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Surgical experience indicates that emergently operating on a moribund patient is likely to yield an unfavorable outcome [17, 18]. Stabilization with ECMO allows for a period of cardiopulmonary recovery, as well as recovery of other end-organ functions before proceeding to repair, potentially improving patient outcomes. The only patients who are poor candidates for this approach are neonates with obstructed total anomalous pulmonary venous return, as pulmonary vein pressure often remains unacceptably high despite mechanical support, and therefore a prompt surgical repair should be performed. Regarding indications for ECMO, one could expect that patients going on ECMO under cardiopulmonary resuscitation would have a worse outcome than those with cardiogenic shock or hypoxemia. However, we found no differences between groups in terms of outcomes. That could be due to insufficient statistical power, or because we have an in-house ECMO team on call 24 hours a day, 7 days a week.
Several indications in our series are worth mentioning specifically: the largest subgroup was the 8 patients with D-transposition of the great arteries/intact ventricular septum and intact or highly restrictive interatrial communication. Five had persistent pulmonary hypertension with right-to-left shunting across the ductus, 2 had an absent ductus arteriosus with right ventricular dysfunction, and 1 had severe hypoxemia and metabolic acidosis that worsened during transfer to our institution. All had failed successful balloon atrial septestomy and maximal medical therapy. Two died after an arterial switch operation, 1 of ongoing pulmonary hypertension and pulmonary hemorrhage and 1 of a large cerebral intraventricular hemorrhage. Transposition of the great arteries/intact ventricular septum with persistent pulmonary hypertension has been classically associated with worse surgical outcomes [17, 18]. Extracorporeal membrane oxygenation enables stabilization and recovery of end-organ function with the circulation in series before surgery. We did not wean from ECMO before arterial switch operation, preferring to deal with end-organ issues with the assistance of a repaired circulation in series. This management strategy has been described before, although some have recommended discontinuation of ECMO before surgery [8, 19].
Another group of patients who have generally had favorable outcomes are those in need for ECMO support because of insufficient pulmonary blood flow (occluded aortopulmonary shunts, tetralogy of Fallot spells, and so forth). These patients can often undergo a straightforward repair with discontinuation of ECMO after surgery [9].
The most striking predictor of hospital death was inability to discontinue ECMO support after surgery. Indeed, the mortality was 70% (7 of 10) for this group of patients. Inability to decannulate after surgery likely represents significant residual cardiopulmonary failure and could be a marker for either irreversible organ injury (often the lungs), an imperfect operation, bad timing, or the wrong operation. Inability to decannulate after surgery can therefore be used as a prognostic marker as well, and the association of a long ECMO run with poor outcome is likely a consequence of the underlying anatomic and pathophysiologic derangement leading to the need to remain on ECMO after surgery. Although patients are all given anticoagulation therapy before going to surgery, postoperative bleeding has not been an insurmountable issue, with 27% of patients requiring reexploration.
The type of circulation (single ventricle versus two ventricles) established after surgery did not affect outcomes in this small series of patients bridged with ECMO to their cardiac surgical procedure. This finding is possibly due to the relatively large number of single-ventricle patients who had low-complexity and low-risk surgical procedures during ECMO support, including aortopulmonary and cavopulmonary shunts (n = 6). When ECMO was used as a bridge to the more complex Norwood procedure in 3 patients, only 1 patient survived (with tricuspid atresia). The 2 other patients who underwent the Norwood operation had HLHS with intact atrial septum, and died of pulmonary complications despite evidence of a good repair. Patients with HLHS and intact atrial septum have been shown to have poor outcomes compared with other variants of HLHS in other studies [20]. The relatively encouraging survival with the single-ventricle population bridged using preoperative ECMO may also reflect the increasing experience and expertise with ECMO management of single-ventricle patients as a whole [21, 22]. Indeed, Hintz and colleagues [21], using data from the registry of the Extracorporeal Life Support Organization, reported the outcome of extracorporeal life support used in neonates for cardiac indications from 1996 to 2000, with no significant difference in survival between HLHS patients and those with other defects. Further evidence for that is that the present series includes 9 patients with single-vessel anatomy (as opposed to single-vessel physiology)—HLHS or anatomic variants (n = 5), pulmonary atresia/intact ventricular septum (n = 2), and tricuspid atresia (n = 2)—with 3 deaths only in this group.
The small number of patients, retrospective nature of the study, the single-institution experience, and the long timespan involved limit drawing definitive conclusions based on this study. However, this study represents the largest series of patients with CHD supported with ECMO as a bridge to a cardiac repair.
In conclusion, ECMO may be a useful modality for bridging patients with CHD and cardiopulmonary collapse to a definitive or palliative cardiac repair. Inability to discontinue ECMO in the operating room after surgical repair is associated with significantly higher mortality.
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