| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2006;82:2233-2239
© 2006 The Society of Thoracic Surgeons
a Pediatric Cardiac Surgery Unit, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Bologna, Italy
c Cardiac Anaesthesia Unit, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Bologna, Italy
b Pediatric Cardiac Surgery Unit, Royal Children’s Hospital, Melbourne, Australia
Accepted for publication June 15, 2006.
* Address correspondence to Dr Oppido, Pediatric Cardiac Surgery, S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy (Email: guidooppido{at}yahoo.com).
Presented at the Poster Session of the Forty-second Annual Meeting of The Society of Thoracic Surgeons, Chicago, IL, Jan 30–Feb 1, 2006.
| This article has been selected for the open discussion forum on the CTSNet Web Site: http://www.ctsnet.org/sections/newsandviews/discussions/index.html
|
 |
Abstract |
|---|
 Top Abstract IntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
METHODS: Between December 1997 and January 2005, 70 consecutive neonates underwent Norwood stage I procedure for hypoplastic left heart syndrome (group A, n = 30), or aortic arch repair for interruption or coarctation with arch hypoplasia (group B, n = 40), with antegrade selective cerebral perfusion (ASCP). Mean weights were 3.0 ± 0.2 kg and 2.8 ± 0.07 kg, and mean ages were 10 ± 3.5 days and 14 ± 10.6 days in groups A and B, respectively. Only 2 patients were older than 30 days. Core body temperature was lowered to 25°C, and mean pump flow during ASCP was initiated at 10 to 20 mL/(kg · min) and adjusted to guarantee a radial/temporal artery pressure of 30 to 40 mm Hg and venous oxygen saturation of more than 70%. Hematocrit was maintained at 30%.
RESULTS: Early mortality was 17% (group A, 23%; group B, 12.5%; p = 0.19). Six late deaths occurred (3 in each group), and at 36 months, Kaplan-Meier overall survival was 64% ± 9.2% in group A and 85% ± 5.7% in group B. One patient had postoperative seizures. Age, weight, sex, prematurity, group A, and ASCP duration did not influence early mortality.
CONCLUSIONS: Antegrade selective cerebral perfusion is a safe and effective procedure and might improve outcome of neonatal aortic arch surgery, minimizing neurologic impact without the need for deep hypothermia.
Deep hypothermic circulatory arrest has been extensively used in the last four decades in cardiac surgery. It was first introduced in pediatric cardiac surgery to facilitate complete repair of congenital heart defects early in life [1–3], providing a bloodless and obstacle-free surgical field. However, the limited "safe" period of time, the incidence of seizures and choreoathetosis, and the high impact on the neurodevelopmental outcome of such a technique [4–8] prompted surgeons to explore safer cerebral protection strategies.
Intermittent cerebral perfusion combined with deep hypothermia, proposed by Kimura and colleagues [9] in 1994, provided a longer uneventful ischemic period for the brain. Since then, many different techniques and strategies have been developed and proposed to achieve a satisfactory continuous cerebral perfusion during the entire procedure [10–13]. Nevertheless, the ideal strategy in terms of flow rate, temperature, gas management, hemodilution, type of cannulation, and the safe duration remains to be determined. The aim of this retrospective study was to evaluate the safety and efficacy of our neonatal antegrade selective cerebral perfusion protocol simultaneous with a decreased reliance on deep hypothermia.
|
Patients and Methods |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
Demographics
Between December 1997 and January 2005, 70 consecutive neonates underwent arch reconstruction with antegrade selective cerebral perfusion. Thirty patients (group A) underwent Norwood stage I operation for hypoplastic left heart syndrome, whilst 40 patients (group B) underwent aortic arch repair for interrupted aortic arch (n = 14) or coarctation of the aorta with arch hypoplasia (n = 26). Demographics variables are summarized in Table 1.
|
Antegrade selective cerebral perfusion (ASCP) is defined as flow maintained into the brain during systemic arrest, whilst selective cerebral and myocardial perfusion (SCMP) is flow maintained into both the brain and coronary arteries during systemic arrest so that the heart is kept beating.
Indication for ASCP was the reconstruction of the aortic arch using cardiopulmonary bypass (CPB) in the situations of hypoplastic left heart syndrome, interrupted aortic arch, complete aortic arch hypoplasia, complex aortic arch hypoplasia (very short proximal arch associated with hypoplastic and long distal arch, and isthmus also known as "bovine truncus" pattern of the arch branches) [14], or coarctation with posterior arch hypoplasia associated with other cardiac lesions. Proximal arch, distal arch, and isthmus were considered hypoplastic when sized less than 60%, 50%, and 40% of the ascending aorta, respectively, according to Moulaert and colleagues [15], or the anterior arch smaller than 1 mm/kg of body weight plus 1, according to Karl and colleagues [16].
Early mortality was within 30 days or any time before hospital discharge. Neurologic complications were defined as the postoperative development of any new neurologic symptoms or signs, evident either clinically or on cerebral ultrasound that was performed routinely in every patient before and after operation.
Operative Variables
Anesthetic protocol included fentanyl (1 to 2 µg/kg/dose), vecuronium (0.1 to 0.2 mg/kg/dose), midazolam (50 to 100 µg/kg/dose), and sevoflurane.
Extracorporeal neonatal circuits sized 3/16" to 1/4" were primed with irradiated and leukodepleted red blood cells and fresh frozen plasma, bicarbonates, and heparin, achieving a hematocrit value of 30%. Arterial cannulae used were Teflon straight cannula (Sofracob s.a., Reventin Vaugris, France) with a 1.5-mm internal diameter tip, or in the smaller patients, 14-gauge peripheral venous catheters (Insyte, Infusion Therapy System Inc, Sandy, UT) partially covered with a suction tube (Fig 1A).
|
Hollow-fiber oxygenators were used throughout (Lilliput D 901, Dideco Modena, Italy). Intermittent antegrade cold blood cardioplegia was administered into the aortic root in all patients who required cardiac arrest. Pump flow was started at a base flow of 150 mL/(kg · min) and adjusted to maintain systemic pressure at no more than 40 mm Hg and mixed venous blood oxygen saturation, continuously monitored, at 60% to 65% or more. For ASCP, flow was reduced to 10 to 20 mL/(kg · min) baseline and adjusted to maintain a venous oxygen saturation of more than 70% as measured in the pump’s systemic venous return line, with a cerebral perfusion pressure (right radial or temporal artery pressure, in case of aberrant right subclavian artery) of between 30 and 40 mm Hg.
Vasoactive drugs were not routinely used during CPB, and gas management was with alpha-stat strategy. Continuous ultrafiltration was done during CPB in each patient. The sternum was only left open when closure resulted in significant hemodynamic deterioration.
Group A Operative Technique
CPB is established between the pulmonary artery/ductus arteriosus and the right atrium with the pulmonary arteries snared. During cooling, a 3.5-mm to 4-mm PTFE graft is anastomosed to the innominate artery, entered with a plastic olive tip needle, and connected to the arterial line. When a nasoesophageal temperature of 25°C is reached, the pulmonary cannula is removed. The base of the innominate artery or proximal arch is then clamped, perfusing the brain, or both brain and myocardium, respectively.
The left common carotid and left subclavian arteries are then snared, the arch is opened, and the main pulmonary artery trunk is directly anastomosed to the arch, after division and patch closure of the pulmonary artery bifurcation. If coarctation is present, the aortic isthmus is resected along with all the ductal tissue, and the descending aorta is connected to the arch with an end-to-end extended anastomosis. The aortic clamp is released and full flow is reinstituted.
Atrial septostomy is done by removing the venous cannula and rerouting the venous return to the CBP machine with pump suckers. A right ventricle-to-pulmonary artery PTFE conduit is then inserted or the modified BT shunt is completed using the conduit previously placed for perfusion.
All 30 patients with hypoplastic left heart syndrome underwent a Norwood stage I variant. Twenty-three underwent direct anastomosis between the main pulmonary artery and the aortic arch concavity, after ductal tissue removal and resolution of the coarctation, when present, with an end-to-end extended anastomosis. The remaining 7 patients underwent arch and ascending aorta reconstruction with a composite heterologous pericardial patch, as previously published [17], and direct side-to-side anastomosis between the aortic root and the main pulmonary artery. Pulmonary circulation was supplied by a PTFE conduit interposed between the innominate and pulmonary arteries confluence in 22 patients or between the right ventricle and the pulmonary arteries confluence in 8.
Group B Operative Technique
Arterial cannulation is attained to the distal ascending aorta (Fig 1B) or to the innominate artery. A second arterial cannula is always inserted in the pulmonary artery or ductus in case of interrupted aortic arch. Bicaval cannulation and vent positioning through the right superior pulmonary vein is always achieved.
Extensive mobilization of aortic arch and branches and descending thoracic aorta is routinely performed to complete a tension-free anastomosis and to avoid left bronchus or tracheal compression. An aberrant right subclavian artery was present in 4 cases and sacrificed in 1 to achieve a tension-free anastomosis.
The ductus arteriosus is doubly ligated and divided before positioning aortic clamps. Ductal tissue is excised and a generous incision made in the aortic arch concavity up to the origin of the brachiocephalic arterial trunk/distal ascending aorta. A second incision is made longitudinally in the posterolateral wall of the descending aorta, achieving an equal circumference of the two aortic ends. An end-to-end extended anastomosis is then completed with a 7-0 absorbable polydioxanone (PDS) monofilament running suture (Ethicon, Inc, Somerville, NJ). In interrupted aortic arch type B, an end-to-side extended anastomosis is done instead between the distal aortic segment and the ascending aorta.
During the arch reconstruction, 15 patients received continuous coronary perfusion through the arterial cannula by clamping the aortic arch just distal to the innominate artery or, in 5 patients, through a second cannula (Insyte 14 GA) inserted into the ascending aorta and connected to the arterial line (Fig 2). The latter could be used for cardioplegia administration during the intracardiac phase when necessary.
|
|
The arch was repaired with end-to-end or end-to-side extended direct anastomosis in 32 and 5 patients, respectively; in the remaining 2 patients, patch aortoplasty was performed. Two patients required an additional procedure for residual gradient within the posterior aortic arch: left subclavian reverse flap aortoplasty and posterior arch enlargement connecting the bases of the left common carotid artery and left subclavian artery, respectively.
A limited period of complete circulatory arrest was used in addition to ASCP in the first consecutive 7 group A patients and 4 group B patients of this series. The internal body temperature in these patients was lowered to 16° to 18°C. In 19 patients from group A, the entire procedure was accomplished with beating heart, with continuous selective cerebral and myocardial perfusion, and 20 patients from group B underwent arch repair with SCMP, with 15 subsequently undergoing cardioplegic arrest for the intracardiac phase. Intraoperative variables are summarized in Table 3.
|
|
Results |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
All patients underwent routine preoperative and postoperative cerebral ultrasound studies; no findings suggestive of cerebral edema, hydrocephalous, or hemorrhage were detected.
On the second postoperative day, seizures developed in 1 group A patient who had undergone a Norwood operation with alternate ASCP and DHCA, and the patient died on postoperative day 7 because of low cardiac output. All other patients were free from neurologic symptoms and at follow-up have been growing and developing normally.
Survival
In the early postoperative period, 7 patients died in group A (23%), and 5 died in group B (12.5%) (p = 0.19). Causes of early death were cardiac in 9 cases and sepsis in 3.
Risk factor analysis of the preoperative and perioperative variables within the two groups revealed that only CPB time in group A and CPB time and myocardial ischemia time in group B reached statistical significance (Table 4). ASCP duration did not affect early mortality in either group.
|
|
|
Comment |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
Since 1992, we have avoided DHCA when arch repair is not mandated and even for repair of intracardiac lesions in neonates with low body weight [18]. Furthermore, we have used antegrade selective cerebral perfusion for arch reconstruction since 1997, thus reducing the hypothermic circulatory arrest time in the early time span of our experience and allowing us to completely avoid it since 1999.
Selective cerebral perfusion can be accomplished by advancing the arterial cannula from the distal ascending aorta into the innominate artery or by positioning the cannula inside the innominate ostia under direct vision upon opening the arch. In these cases, a brief period of circulatory arrest may be necessary to safely achieve this and to complete the reconstruction. This problem can be obviated by innominate artery cannulation either directly using an appropriately sized soft-tipped cannula or with a PTFE interposition graft.
In examining risk factors influencing early mortality, the only variables that reached statistical significance were CPB time in group A and CPB and myocardial ischemia time in group B. However, prolonged CPB and aortic cross-clamp time may not constitute risk factors themselves but could simply reflect a more complex procedure or the need for prolonged circulatory assistance due to difficulty in weaning from bypass. Indeed, ASCP duration was not a risk factor, thus demonstrating that ASCP, when compared with DHCA, can provide a longer safe period for the patient.
Group A experienced higher early mortality as well as lower survival compared with group B, even though differences did not reach statistical significance. We suspect that the introduction of ASCP in our experience may have had a beneficial impact on outcome particularly on group A patients, thus contributing to reduced early and late mortality of this challenging group of patients.
The use of both DHCA and ASCP in patients during the same procedure was limited to our early experience of this series (11/70 patients). Nevertheless, this approach did not seem to have higher risk, although certainly the introduction of ASCP would have minimized cerebral ischemic time and thus might have positively affected outcome.
Hypothermia has been proven to decrease cellular metabolism, lowering oxygen consumption, and consequently reducing the adverse impact of ischemia [19, 20]; conversely, deep hypothermia is suspected to be responsible for tissue damage on the brain and lung [21], capillary leak syndrome, generalized inflammatory reaction, and coagulopathy. Moreover, deep hypothermia should be combined with a higher degree of hemodilution to counteract increased fluid viscosity and cell membrane rigidity, which consequently reduces the blood’s oxygen-carrying capacity. Recent studies have showed the superiority of brain protection for higher hematocrit levels [22, 23]. We believe that when ASCP is performed, deep hypothermia is no longer needed, thus a moderate grade of hypothermia with a mild degree of hemodilution might be effective in protecting other organs from ischemic damage and optimizing cerebral oxygen supply.
The appropriate perfusion rate for the brain in the neonate during selective cerebral perfusion remains controversial. During selective cerebral perfusion an ideal flow rate of 50 mL/(kg · min) has been advocated on the basis of theoretical calculations [10], but many different protocols have been proposed to date (Table 5). This uncertainty regarding optimum cerebral flow and the management of the ASCP has prompted surgeons to use control systems to evaluate the effectiveness of cerebral perfusion, such as transcranial Doppler ultrasonography or near-infrared spectroscopy. Nevertheless, best method to evaluate and adjust flow during ASCP is still being debated. Near-infrared spectroscopy may lead to cerebral hypercirculation if used alone [24]; however, cerebral blood volume index exhibited a poor correlation with cerebral blood flow velocity [25]. In the same study mean lower body arterial (femoral or umbilical) pressure correlated poorly with the required bypass rate [25].
|
Conversely, it can be worthwhile to maintain an arterial PaO 2 above 400 mm Hg, particularly during ASCP, when considering that hypothermia itself shifts the hemoglobin dissociation curve to the left, decreasing oxygen release and, therefore, making dissolved oxygen a more vital source of oxygen to tissues.
The present analysis shares the limitations inherent with retrospective clinical studies. The major imitation is the lack of a sensitive means of detecting more subtle neurologic complications.
The heterogeneity of the population can represent another major limitation of this study; however, as far as possible, we attempted to separate the two groups for the purposes of data analysis, respecting the differing nature in terms of anatomy, physiology, surgical challenges, and problems inherent to the individual groups. Long-term specific neurodevelopment evaluation is needed.
In conclusion, antegrade selective cerebral perfusion is a safe and effective procedure and might improve outcome of neonatal aortic arch surgery, minimizing neurologic complications without the need for deep hypothermia.
|
Acknowledgments |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
|
References |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  J. Salazar, R. Coleman, S. Griffith, J. McNeil, H. Young, J. Calhoon, F. Serrano, and R. DiGeronimo Brain preservation with selective cerebral perfusion for operations requiring circulatory arrest: protection at 25 {degrees}C is similar to 18 {degrees}C with shorter operating times Eur. J. Cardiothorac. Surg., September 1, 2009; 36(3): 524 - 531. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Zhang, P. Cheng, J. Hou, L. Li, H. Liu, R. Liu, B. Ji, and Y. Luo Regional cerebral perfusion for surgical correction of neonatal aortic arch obstruction Perfusion, May 1, 2009; 24(3): 185 - 189. [Abstract] [PDF]
|
|
|
|
 |
|
 G. Gargiulo, G. Oppido, E. Angeli, and C. P. Napoleone Neonatal aortic arch surgery MMCTS, July 23, 2007; 2007(0723): 2345. [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 |
