| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Click here to read this article as a CME activity
The Nemours Cardiac Center; Alfred I. duPont Hospital for Children, Wilmington, Delaware
Accepted for publication December 12, 2007.
* Address correspondence to Dr Pizarro, Alfred I. duPont Hospital for Children, PO Box 269, 1600 Rockland Rd, Wilmington, DE 19899 (Email: cpizarro{at}nemours.org).
| Pediatric cardiac surgery:
The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal.
|
 |
Abstract |
|---|
 Top Abstract IntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
Methods: We reviewed our experience with stage II reconstruction after hybrid palliation in high-risk newborns with hypoplastic left heart syndrome and variants, focusing on the hemodynamic, reintervention, and operative data.
Results: Among 14 patients undergoing hybrid palliation, interstage reinterventions targeted the ductal stent in 2, the atrial septal communication in 3, and the pulmonary artery bands in 1 patient. The median ratio of pulmonary blood flow to systemic blood flow (Qp/Qs) was 0.76, and pulmonary artery pressure was 14 mm Hg. Stage II reconstruction was performed in 8 patients with a median age of 4 months (range, 3.2 to 5.8 months) and a median weight of 4.9 kg (range, 3.7 to 6.0 kg). Median cardiopulmonary bypass time was 124 minutes (range, 95 to 188 minutes). Median time to extubation was 20 hours (range, 9 to 120 hours). Median oxygen saturation at hospital discharge was 79% (range, 78% to 82%). Two perioperative deaths occurred. To date, all hospital survivors are well. Four patients have completed a Fontan.
Conclusions: Stage II reconstruction after hybrid palliation for high-risk neonates carries important morbidity and mortality. A considerable number of reinterventions to optimize the palliated physiology are necessary. This approach can provide appropriate preparation for single-ventricle management while avoiding cardiopulmonary bypass in the neonate. Additional experience and critical risk assessment of the entire strategy are necessary to define its advantages.
| This article has been selected for the open discussion forum on the CTSNet Web Site: http://www.ctsnet.org/sections/newsandviews/discussions/index.html
|
The management of congenital heart lesions characterized by the presence of a single ventricle associated with ductal-dependent systemic outflow obstruction has evolved into a sequence of staged interventions, including an extensive surgical reconstruction in the neonatal period. Despite a significant improvement in early survival after stage I Norwood palliation, neonates with associated prematurity, low birth weight, noncardiac conditions, or genetic abnormalities are considered at higher risk, with a stage I mortality of 40% to 50% [1–3]. In addition, concern about the cumulative effect of this intervention on neurodevelopmental function and the inherently unstable physiology these patients exhibit has prompted an ongoing search for novel treatment strategies to improve outcomes [4, 5].
In this scenario, stenting of the ductus arteriosus and banding the branch pulmonary arteries (hybrid approach) has been revisited at various centers with encouraging early results [6–9]. However, few limited data exist on the effectiveness of this palliative approach beyond the initial postoperative period and the suitability of these patients to accomplish a successful cavopulmonary connection.
|
Material and Methods |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
The study was approved by the local Institutional Review Board (2005-100). Given the retrospective nature of this review and elimination of any identification data, requirement for individual patient consent was waived.
Initial Hybrid Palliation
Technical aspects of the initial hybrid (off-pump) palliation have been reported previously [8]. In summary, branch pulmonary artery banding was performed through a median sternotomy using 3.5-mm Gore-Tex (W. L. Gore, Newark, DE) rings before stent deployment. Tightness of the bands was usually adjusted over a 2.5-mm coronary probe placed alongside the branch pulmonary artery to achieve an arterial oxygen saturation of about 80%. Stenting of the ductus arteriosus was performed through a sheath placed directly into the proximal main pulmonary artery. Stent size and positioning was based on a lateral angiogram through the sheath. Initially, relatively short, 8- x 10-mm premounted balloon-expandable stents (Palmaz-Genesis, Cordis, Miami, FL) were used in 6 patients, whereas recently, longer 8- x 17-mm balloon-expandable (Palmaz-Genesis) and 7- x 20-mm self-expandable (Protégé GPS, ev3, Plymouth, MN) stents have been used in 2 patients. The choice of stent was largely influenced by ductal anatomy and availability.
The adequacy of the atrial septal communication was determined from hemodynamic and echocardiographic data. If the atrial septal communication was thought to be restrictive (mean gradient >5 mm Hg), and according to the nature of this restriction, a balloon atrial septotomy (n = 4) or deployment of an atrial septal stent (n = 2) was performed. Routine echocardiographic assessment was performed on admission to the intensive care unit and weekly until discharged.
Interstage Follow-Up
Outpatient follow-up, including an echocardiogram, was performed at intervals of 2 to 3 weeks or sooner, depending on the clinical condition. All patients were referred for complete hemodynamic, angiographic, and echocardiographic evaluation at 12 weeks, or earlier if a hemodynamic issue was suspected. Because of the technical limitations with direct measurement of pulmonary artery pressure through the bands, and when feasible, mean pulmonary artery pressure was estimated by measurement of pulmonary vein wedge pressure. Combined arch reconstruction and superior cavopulmonary connection was electively scheduled at 16 to 20 weeks of age.
Combined Stage II Surgical Reconstruction
The combined stage II surgical reconstruction consisted of amalgamation of the proximal ascending aorta with the main pulmonary artery, removal or resection of the ductus/stent complex, aortic arch reconstruction, atrial septectomy (with or without removal of atrial septal stent), removal of the branch pulmonary artery bands with arterioplasty, if necessary, and superior cavopulmonary connection.
The surgical reconstruction was performed using deep hypothermic circulatory arrest with periods of intermittent reperfusion in the last 6 patients. Myocardial protection consisted of single-dose crystalloid cardioplegia. Aortic arch reconstruction was performed after removal ("endarterectomy-like") of the stent or en bloc resection of the ductus arteriosus/proximal descending aorta complex (Fig 1). In the latter case, ample mobilization of the descending aorta, aortic arch, and brachiocephalic vessels was necessary to achieve the reconstruction without tension. Reconstruction or reimplantation of the distal arch/ductus confluence was performed depending on the integrity of the distal arch orifice, commonly straddled by the ductal stent. Amalgamation of the proximal main pulmonary artery and ascending aorta was performed to complete the neoaortic reconstruction using a pulmonary artery homograft patch in all cases.
|
Postoperative management was aimed at early extubation and targeted a PaO 2 exceeding 35 mm Hg. Severe and persistent hypoxemia unresponsive to volume expansion, permissive hypercapnia, and inspired nitric oxide were the criteria for takedown of the cavopulmonary connection to a systemic–pulmonary artery shunt.
|
Results |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
|
|
The median duration of cardiopulmonary bypass was 124 minutes (range, 95 to 188 minutes), deep hypothermic circulatory arrest was 65.1 minutes (range, 39 to 78 minutes), and myocardial ischemia was 82.6 minutes (range, 67 to 105 minutes). The median duration of mechanical ventilation was 20 hours (range 9 to 120 hours), but was significantly prolonged in a patient with severe left lung hypoplasia and postoperative anasarca. The median preoperative lactate level was 1.5 mmol/L (range, 1.3 to 3.8 mmol/L), peaked at 7.2 mmol/L (range, 3.1 to 10.7 mmol/L) in the immediate postoperative period, and returned to normal within 18 hours.
Three patients exhibited transient seizure activity in the immediate postoperative period and recovered without evidence of neurologic deficit by the time of discharge. Intracranial hemorrhage occurred in 1 patient. Important and persistent hypoxemia was associated with two of these neurologic events. The median hospital stay was 26 days (range, 6 to 105 days), but was significantly prolonged in 3 patients owing to postoperative supraventricular dysrhythmias. At the time of discharge, median oxygen saturation was 79% (range, 78% to 82%), and all patients exhibited normal sinus rhythm.
There were two operative deaths. One patient who died had complex transposition and aortic arch hypoplasia and sustained a cerebral hemorrhage in the perioperative period, and the second patient had significant bleeding associated with hypoxemia as a consequence of disruption of the left pulmonary artery upon removal of the band. At a median follow-up of 33 months (range, 15 to 81 months), there was one trauma-related late death. One patient awaits Fontan, and 4 others have undergone Fontan completion and remain well.
|
Comment |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
Hemodynamic assessment after hybrid palliation showed reasonable preservation of ventricular function, a balance of the systemic and pulmonary circulations with comparatively less volume load than conventional surgical palliation, and in most cases, reasonable protection of the pulmonary vascular bed. A pressure gradient across the ductal stent or atrial septal communication was commonly detected and prompted catheter intervention or early surgery, as has been noted in other series [6, 7, 9]. Although the pressure gradient across the ductus was commonly related to incomplete stenting of ductal tissue early in this experience, the use of longer stents has not completely eliminated the development of progressive obstruction, commonly associated with accumulation of neointimal tissue, particularly in the presence of unusual ductal anatomy.
Adequacy of the atrial septal communication had a variable course depending on anatomic features such as true deficiency of septum primum, posterior deviation of the atrial septum, and antegrade flow through the left heart. These factors played an important role influencing the impact of a restriction at the level of the atrial septal communication and the technical aspects of establishing an unobstructed communication. Our experience echoes the significant learning curve and the considerable number of interstage reinterventions before stage II, as previously reported [6, 7, 9].
Although early transition to a combined stage II reconstruction can be applied to shorten the vulnerable interstage period, reducing the duration of initial palliation to no more than 12 to 16 weeks after a hybrid approach, this has not completely eliminated the need to address important hemodynamic issues. In this cohort, 3 patients transitioned to stage II earlier than the scheduled 4 months due to recurrent hemodynamic issues, including 1 patient in whom the cavopulmonary connection was taken down to a systemic–pulmonary artery shunt due to severe hypoxemia.
Considering the fact that early stage II is usually associated with lower arterial oxygen saturation and prolonged hospital course [10], the presence of a suboptimal palliated state could easily lead to increased morbidity and a poor outcome. This reinforces the concept that strict patient surveillance is essential to detect and promptly address such problems, restoring the optimal palliated physiology necessary to achieve a successful cavopulmonary connection. In this scenario, an intervention to effectively restore optimal physiologic conditions should be carefully balanced against early transition to a second stage and the inherent risk of important hypoxemia due to a failed superior cavopulmonary connection.
The idea that the hybrid approach could allow time for the small patient to gain weight before the extensive surgical intervention appeared to be only applicable to premature newborns. The difficulties with growth and development observed in the post-Norwood population were also observed in these patients, who at the time of operation were well below the 15th percentile for weight, despite appropriate caloric intake. This should not constitute an unexpected finding, particularly in a population who exhibited important comorbidities and in some cases a residual hemodynamic burden.
Stage II reconstruction after hybrid palliation represents a formidable technical challenge involving the reconstruction of the aortic arch, proximal neoaorta, and superior cavopulmonary connection. The complexity of this procedure can increase even more if repair of the branch pulmonary arteries, distorted by the placement of bands, and atrial septectomy are necessary. A lengthy reoperative procedure, the common presence of ventricular hypertrophy, and flow disturbance in the brachiocephalic vessels require effective myocardial as well as neuroprotection.
Although periods of circulatory arrest were minimized and intermittent reperfusion was commonly used during arch reconstruction in this cohort, neurologic events remained the most common postoperative issue. The exact pathophysiology behind these events is likely multifactorial and possibly relates to the magnitude of the surgery and the use of circulatory arrest for the arch and the hemi-Fontan-type reconstruction. In addition, the presence of postoperative hypoxemia, cerebral venous congestion, and decreased cerebral blood flow due to abnormal cerebrovascular autoregulation after a period of deep hypothermia and cerebral ischemia [4] could have contributed to a cumulative insult during the immediate perioperative period. It should be noted that the association of hypoxemia and cerebral venous congestions could lead to a neurologic dysfunction, considering the reciprocal relationship between cerebral and pulmonary feedback loops after superior cavopulmonary connection [11]; therefore, any efforts to increase oxygenation can only occur at the expense of cerebral vasodilation and increased cerebral venous pressure.
The high incidence of neurologic events prompted us to significantly reduce the use of circulatory arrest, increase the periods of intermittent reperfusion, and consider early takedown of the superior cavopulmonary connection to a systemic–pulmonary artery shunt any time important hypoxemia could be mitigated with usual medical measures. Although the use of regional cerebral perfusion could intuitively appear to offer a solution to the issue of neurologic morbidity, this has not been associated with improvement in neurodevelopmental function, as shown by the only randomized clinical trial to date [12]. In fact, the tendency to worse point estimates with the use of this strategy could be a function of increased cerebrovascular resistance and cerebral edema leading to hypoxemia. Development of improved perfusion strategies aimed at preservation of cerebral autoregulation could have a favorable effect by virtue of lowering cerebrovascular resistance combined with the concomitant increase in cerebral oxygenation in these patients.
Reconstruction of the aortic arch was largely influenced by features of the stenting of the ductus. When the ductus was excised, extensive mobilization of the brachiocephalic vessels and descending aorta was required to bridge the long gap between the proximal main pulmonary artery and the descending thoracic aorta during the reconstruction. In the absence of a true coarctation shelf, when the stent was not straddling the opening of the distal arch into the ductus, the distal resection line usually preserved the distal arch–thoracic aorta continuity. This facilitated the repair and reduced the potential for technical problems, including compression of the left mainstem bronchus and phrenic injury, among others.
Depending on the elapsed time and the endovascular reaction after stent deployment, a stent extending into the thoracic aorta was removed at least partially, leaving adventitia and portions of the media intact ("endarterectomy-like"), thus reducing the magnitude of the repair. Development of recurrent obstruction observed in 2 patients was not related to removal or excision of the stent and resulted in a rate of reintervention similar to that reported by other centers [6] or after conventional Norwood reconstruction.
Our experience confirms the observation that after band removal, the branch pulmonary arteries reexpanded in most cases, leaving no evidence of residual stenosis due to intimal proliferation. This may be in part attributed to the use of polytetrafluoroethylene bands, which appear to elicit a minimal inflammatory reaction in the vascular wall. Because most patients had a hemi-Fontan connection, the central pulmonary arteries were routinely patch augmented; therefore, a separate pulmonary artery patch reconstruction was not necessary.
Owing to the hemodynamic advantages of a superior cavopulmonary connection [13], it was not unexpected that despite the extensive surgery, the postoperative period of these patients was characterized by excellent peripheral perfusion, prompt normalization of lactate levels, and a short duration of mechanical ventilatory support. Takedown of the superior cavopulmonary connection to a systemic–pulmonary artery shunt occurred in 1 patient with severe left lung hypoplasia and persistent postoperative hypoxemia. It is possible that despite the presence of appropriate preoperative hemodynamic conditions, a prolonged period of cardiopulmonary bypass could have contributed to a significant increase in pulmonary vascular reactivity [13–16].
Our results demonstrate that stage II reconstruction still carries a significant morbidity and mortality in a cohort of patients with serious comorbidities and residual hemodynamic issues somehow related to the incremental technical challenge of implementing this strategy among very small and premature newborns. This observation concurs with the report by Bacha and colleagues [9] on the management of high-risk patients with hypoplastic left heart syndrome, and is not too dissimilar when this strategy has been applied to patients otherwise considered good candidates for conventional surgical palliation [7, 17]. At present, the risk for death is difficult to define, given the limited experience, the small number of patients, and the variability of clinical characteristics among series, including the use of this strategy to manage patients who ultimately underwent cardiac transplantation or biventricular repair [17].
The extensive surgical reconstruction and the physiologic requirements for a successful cavopulmonary connection demand an effective preoperative palliation and a flawless technical exercise to achieve a successful outcome and reduce the morbidity and mortality associated with this approach. In the absence of these preoperative and operative conditions, the possibility to follow the initial hybrid palliation with a conventional Norwood procedure should be considered.
Completion of a Fontan circulation in 4 of 6 stage II survivors confirms the notion that this palliative approach can provide the hemodynamic conditions necessary to achieve the ultimate physiologic goal for patients with a single ventricle. Although these results are encouraging, the morbidity and mortality associated with the stage II surgical reconstruction should be factored in the overall risk associated with this hybrid approach. A comprehensive evaluation of the risks and morbidity from the time of initial palliation leading to the Fontan circulation will be necessary before a meaningful comparison with the conventional surgical palliation can be made. As the hybrid approach continues to evolve, it should be expected that additional experience, procedural refinement, and follow-up would help to define its true indications and potential benefits, particularly with regards to neurodevelopmental outcome.
The retrospective nature of this study, the small number of subjects, and the lack of a control group do not allow meaningful statistical analysis or the comparison with alternative management options. Owing to the consistent and uniform operative management of these patients, no inferences could be drawn about potentially important determinants of outcome such as perfusion strategy, timing of surgery, type of arch reconstruction, or superior cavopulmonary connection, among others. These important limitations do not allow placement of the outcomes after the hybrid approach within the context of current surgical palliation.
|
Acknowledgments |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
|
References |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentAcknowledgmentsReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  O. Honjo, L. N. Benson, H. E. Mewhort, D. Predescu, H. Holtby, G. S. Van Arsdell, and C. A. Caldarone Clinical Outcomes, Program Evolution, and Pulmonary Artery Growth in Single Ventricle Palliation Using Hybrid and Norwood Palliative Strategies. Ann. Thorac. Surg., June 1, 2009; 87(6): 1885 - 1893. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
