Neonatal Aortic Arch Reconstruction Avoiding Circulatory Arrest and Direct Arch Vessel Cannulation

Neonatal Aortic Arch Reconstruction Avoiding Circulatory Arrest and Direct Arch Vessel Cannulation Christo I. Tchervenkov, MD, Stephen J. Korkola, MD, Dominique Shum-Tim, MD, Christos Calaritis, BS, Eric Laliberté, CPC, Teodoro U. Reyes, MD, and Josée Lavoie, MD Divisions of Cardiovascular Surgery and Anesthesia, The Montréal Children s Hospital, McGill University Health Center, Montréal, Québec, Canada Background. Aortic arch reconstruction in neonates routinely requires deep hypothermic circulatory arrest. We reviewed our experience with techniques of continuous low-flow cerebral perfusion (LFCP) avoiding direct arch vessel cannulation. Methods. Eighteen patients, with a median age of 11 days (range 1 to 85 days) and a mean weight of 3.2 0.8 kg, underwent aortic arch reconstruction with LFCP. Seven had biventricular repairs with arch reconstruction, 9 underwent the Norwood operation and 2 had isolated arch repairs. In 1 Norwood and 7 biventricular repair patients, LFCP was maintained by advancing the cannula from the distal ascending aorta into the innominate artery. In 8 of 9 Norwood patients, LFCP was maintained by directing the arterial cannula into the pulmonary artery confluence and perfusing the innominate artery through the right modified Blalock Taussig shunt fully constructed before cannulation for cardiopulmonary bypass. In 2 patients requiring isolated arch reconstruction, the ascending aorta was cannulated and the cross-clamp was applied just distal to the innominate artery. Results. LFCP was maintained at 0.6 0.2 L min 1 m 2 for 41.0 13.9 minutes at 18.5 C 1.1 C. In 10 of the 18 patients, blood pressure during LFCP was 15 8 mm Hg remote from the innominate artery (left radial, umbilical or femoral arteries). In 8 of the 18 patients, right radial pressure during LFCP was 24 10 mm Hg. The mean mixed-venous saturation was 79.8% 10% during LFCP. Two patients had preoperative seizures, whereas none had seizures postoperatively. One patient died. Conclusions. Neonatal aortic arch reconstruction is possible without circulatory arrest or direct arch vessel cannulation. These techniques maintained adequate mixed-venous oxygen saturations with no associated adverse neurologic outcomes. (Ann Thorac Surg 2001;72:1615 20) 2001 by The Society of Thoracic Surgeons The use of deep hypothermic circulatory arrest (DHCA) has played an important role in developing successful repair techniques for complex congenital heart disease. However, in the last several years there has been a trend away from the use of DHCA because of the potential adverse neurologic outcomes associated with its use [1 3] and the finding that low-flow perfusion may provide better cerebral protection [4, 5]. As a result, most intracardiac repairs in early life are now routinely carried out on cardiopulmonary bypass. Despite this trend, reconstruction of the aortic arch is still routinely performed with DHCA. Recently, we and others have been devising techniques of aortic arch reconstruction that avoid or limit the period of DHCA in order to decrease the risk for Presented at the Poster Session of the Thirty-seventh Annual Meeting of The Society of Thoracic Surgeons, New Orleans, LA, Jan 29 31, 2001. Address reprint requests to Dr Tchervenkov, Department of Cardiovascular Surgery, Room C-829, The Montreal Children s Hospital, McGill University Health Center, 2300 Tupper St, Montréal, QB, H3H 1P3, Canada; e-mail: christo.tchervenkov@muhc.mcgill.ca. neurologic injury [6 12]. In this report, we review our recent experience with three techniques of neonatal aortic arch reconstruction that avoid the use of DHCA and direct arch vessel cannulation, while maintaining continuous low-flow cerebral perfusion (LFCP). Patients and Methods At The Montreal Children s Hospital, 18 patients underwent reconstruction of the aortic arch without circulatory arrest or direct arch vessel cannulation between June 1996 and June 2000. We have not used circulatory arrest for aortic arch reconstruction for any patient since July 1999. Therefore, the last 14 patients described in this series were consecutive. Concomitant intracardiac repair was carried out in 16 patients, whereas 2 patients underwent isolated aortic arch reconstruction. The operations were primary in 17 patients and a reoperation in 1 patient, who had previously undergone biventricular repair for hypoplastic left heart complex. The median age was 11 days (range 1 to 85 days) and the mean weight was 3.2 0.8 kg. 2001 by The Society of Thoracic Surgeons 0003-4975/01/$20.00 Published by Elsevier Science Inc PII S0003-4975(01)03063-6

1616 TCHERVENKOV ET AL Ann Thorac Surg NEONATAL AORTIC ARCH RECONSTRUCTION 2001;72:1615 20 Table 1. Patient Characteristics Patient No. Age (days) Weight (kg) Diagnosis Procedure Outcome 1 12 3.8 HLHS Norwood 2 6 3.2 VSD, arch hypoplasia VSD closure, arch repair 3 21 2.2 d-tga, RV hypoplasia, multiple Norwood VSD, arch hypoplasia 4 7 3.2 d-tga, arch hypoplasia Arterial switch, ASD closure, arch repair 5 9 2.2 CAVC, LV hypoplasia, ASD, Norwood Dead arch hypoplasia, coarctation 6 31 3.4 VSD, arch hypoplasia, VSD repair, arch repair coarctation 7 7 2.7 HLHS Norwood 8 21 2.7 DILV, TGA, restrictive Norwood bulboventricular foramen, arch hypoplasia, coarctation 9 12 3.1 DORV, ASD, arch hypoplasia Arterial switch, VSD/ASD closure, arch repair 10 14 2.5 CAVC, LV hypoplasia, arch Norwood hypoplasia 11 11 3.0 HLHS Norwood 12 73 4.2 CAVC, ASD, arch hypoplasia CAVC repair, ASD closure, arch repair 13 12 2.9 HLHS Norwood 14 1 3.2 HLHS Norwood 15 3 3.9 VSD, subaortic stenosis, ASD VSD/ASD closure, resection arch hypoplasia subaortic stenosis, arch repair 16 7 3.5 VSD, ASD, arch hypoplasia, VSD/ASD repair, arch repair coarctation 17 4 2.5 ASD, PA and arch aneurysms ASD closure, pulmonary valvectomy, PA and arch repair 18 85 5.3 Recurrent arch obstruction after 2 ventricle repair for HLHC Arch repair ASD secundum atrial septal defect; CAVC complete atrioventricular canal; DILV double-inlet left ventricle; DORV double-outlet right ventricle; d-tga d-transposition of the great arteries; HLHC hypoplastic left heart complex; HLHS hypoplastic left heart syndrome; LV left ventricle; PA pulmonary artery; RV right ventricle; VSD ventricular septal defect. Cardiac Malformations The cardiac malformations with their corresponding aortic arch pathology and surgical repairs are summarized in Table 1. Aortic Arch Pathology Seventeen of 18 patients had aortic arch obstruction by virtue of hypoplasia or coarctation, or both (Table 1). The remaining patient was born with an aneurysm of the aortic arch accompanied by aneurysms of the pulmonary arteries. Five patients had a classic hypoplastic left heart syndrome. We use criteria suggested by Karl and associates [13] to define aortic arch hypoplasia requiring intervention. If the transverse aortic arch diameter as measured on echocardiography is less than the patient s weight in kilograms 1, the arch is considered hypoplastic. For example, in a 3-kg infant, if the aortic arch is less than 4 mm (ie, 3 1), we consider it hypoplastic and would enlarge the arch surgically. We believe that although residual aortic arch hypoplasia after coarctation repair may be well tolerated by an otherwise normal heart, this deformity will present a significant anatomic afterload and will not be tolerated by a heart undergoing complex intracardiac repair with a significant duration of myocardial ischemia and cardiopulmonary bypass. Surgical Techniques We have used three techniques for LFCP during aortic arch reconstruction, depending on its extent and the nature of the intracardiac repair. These techniques completely avoid the use of DHCA and direct arch vessel cannulation. Continuous LFCP under deep hypothermia is maintained through the innominate artery. Each surgical technique for LFCP is described below. TECHNIQUE 1. In 7 patients undergoing biventricular repair and in 1 patient the Norwood operation, the ascending aorta was large enough to be cannulated (Fig 1). After median sternotomy and systemic heparinization, a flexible aortic cannula (8F, BioMedicus, Medtronic, Minneapolis, MN) was placed in the right side of the distal ascending

Ann Thorac Surg TCHERVENKOV ET AL 2001;72:1615 20 NEONATAL AORTIC ARCH RECONSTRUCTION 1617 Fig 1. Technique 1. The right side of the ascending aorta is cannulated 5 mm proximal to the innominate artery. Under deep hypothermia, the arterial cannula is advanced into the innominate artery and snared in place. A clamp is placed on the descending thoracic aorta and the left subclavian and carotid arteries are snared while continuous low-flow cerebral perfusion is maintained through the innominate artery. Arch reconstruction is carried out using pulmonary homograft patch aortoplasty. these cases, LFCP was therefore maintained by retrograde perfusion of the modified Blalock Taussig shunt (MBTS) into the innominate artery, fully constructed before CPB [6]. After median sternotomy, the innominate artery and the right pulmonary artery (PA) were mobilized. Patients were fully heparinized and a 3.5 mm MBTS (Gore-Tex; W. L. Gore and Associates, Flagstaff, AZ) was completely constructed, before cannulation for CPB, between the innominate artery and the right PA. Clamping of the right PA significantly decreased the run-off into the pulmonary arteries and was associated with an increased blood pressure and hemodynamic stability. Compromise to coronary blood flow was avoided by clamping the proximal right PA to the left of the ascending aorta and by placing gentle traction sutures on the left side of the diminutive ascending aorta. A flexible arterial cannula (8F, BioMedicus, Medtronic) was placed in the proximal third of the PDA and directed distally toward the descending aorta. Standard rightangled cannulas were placed in the inferior and superior vena cavas for venous drainage. The PDA was then snared proximal to the arterial cannulation and the MBTS was clamped just before initiating full-flow CPB. The patients were cooled systemically to 18 C. During cooling, with the heart beating, the main PA was transected just before its bifurcation and the distal end was closed with a pulmonary homograft patch. After the patient reached deep hypothermia, the arterial cannula was redirected into the PA confluence, the PDA snare aorta, approximately 5 mm proximal to the origin of the innominate artery. Standard bicaval cannulation was performed for the venous drainage and cardiopulmonary bypass (CPB) was established. The patent ductus arteriosus (PDA) was immediately ligated and the patient was cooled to 18 C. Intracardiac repair was performed during cooling. The aortic cannula was then advanced into the innominate artery without taking it out and was snared in place. The left subclavian and left common carotid arteries were also snared and a vascular clamp was applied to the upper descending thoracic aorta to isolate the aortic arch. The entire aortic arch was then reconstructed by the technique of pulmonary homograft patch aortoplasty [14], while maintaining LFCP at 0.3 to 0.8 L min 1 m 2 through the innominate artery. Releasing the clamp from the descending aorta or the snares from the left carotid or subclavian arteries during LFCP resulted in brisk back-bleeding, suggesting significant blood flow to the brain and the lower body. After removing air from the ascending aorta by releasing the distal clamp, the aortic cannula was pulled back from the innominate artery into the ascending aorta. The head vessels were unsnared, full perfusion was reestablished, and the patient was rewarmed and weaned from cardiopulmonary bypass. TECHNIQUE 2. In 8 of 9 patients undergoing the Norwood operation, the ascending aorta was too small to allow direct cannulation with the arterial cannula (Fig 2). In Fig 2. Technique 2. A modified Blalock Taussig shunt is fully constructed before cannulation for cardiopulmonary bypass. The arterial cannula is advanced into the pulmonary artery confluence through the patent ductus arteriosus and low-flow cerebral perfusion is maintained by retrograde flow through the shunt into the innominate artery, with the branch pulmonary arteries snared. Snares on the arch vessels and a clamp on the descending thoracic aorta, allow reconstruction of the aortic arch, ascending aorta, and proximal pulmonary artery with a pulmonary homograft patch.

1618 TCHERVENKOV ET AL Ann Thorac Surg NEONATAL AORTIC ARCH RECONSTRUCTION 2001;72:1615 20 Fig 3. Technique 3. The distal aortic arch is isolated by applying a clamp just distal to the innominate artery, a second clamp to the descending thoracic aorta, and snaring of the left carotid and left subclavian arteries. While cerebral perfusion is maintained through the ascending aorta into the innominate artery, the aortic arch is reconstructed. was moved distally, and both branch PAs were snared. The MBTS was opened and LFCP was initiated retrogradely through the innominate artery. The proximal innominate, the left carotid and the left subclavian arteries were snared and the descending aorta was clamped to allow isolation of the aortic arch. This technique completely avoided DHCA during the completion of the Norwood operation [6]. The arterial cannula was then transferred to the neoaorta, followed by clamping of the MBTS and removal of the snares from the head vessels and of the distal aortic clamp. The proximal PDA was suture-ligated and the snares from the branch pulmonary arteries were also removed. The patients were rewarmed and weaned from CPB. TECHNIQUE 3. Two patients required isolated reconstruction of the distal aortic arch (Fig 3). One had an aortic arch aneurysm associated with PA aneurysms, whereas the other had recurrent arch obstruction after twoventricle repair for hypoplastic left heart complex. In these cases, aortic arch reconstruction was performed by cannulation of the ascending aorta and systemic cooling to a nasopharyngeal temperature of 19 C. While the patient was on CPB, a clamp was applied to the proximal aortic arch just distal to the innominate artery. A second clamp was applied to the upper descending thoracic aorta while snaring the left carotid and left subclavian arteries. Cerebral perfusion was thus maintained through the arterial cannula perfusing ascending aorta and the innominate artery. In both cases, the aortic arch was reconstructed with a pulmonary homograft patch aortoplasty. Results Low-Flow Cerebral Perfusion Low-flow cerebral perfusion was maintained during the entire period of aortic arch reconstruction. The mean flow was maintained at 0.6 0.2 L min 1 m 2 for a mean period of 41.0 13.9 minutes at 18.5 1.1 C (nasopharyngeal). In 10 of 18 patients, the arterial pressure was measured at a site remote from the innominate artery (left radial, umbilical or femoral arteries) during the period of LFCP. The mean arterial pressure was maintained at 15 8 mm Hg in these cases. In the remaining 8 patients, arterial pressure was recorded from the right radial artery and found to be 24 10 mm Hg during the period of LFCP. During the period of LFCP, releasing the clamp from the descending aorta or the snares from the left carotid or left subclavian arteries resulted in brisk back-bleeding, suggesting a significant amount of trophic blood flow to the left side of the upper body and lower body by perfusing only the innominate artery. Mixed-Venous Oxygen Saturation Oxygen saturation was measured continuously in the venous cannula with an oximeter attached to the venous line of the CPB circuit. Data were available for 14 of the 18 patients. The lowest mixed-venous oxygen saturation during the period of LFCP was 79.8% 10%. Clinical Outcome One patient with complete atrioventricular canal, secundum atrial septal defect, hypoplastic left ventricle, aortic arch hypoplasia, and coarctation died of low output state on postoperative day 1 after a Norwood operation. Although 2 patients experienced preoperative seizures, no patients had seizures or other adverse neurologic events postoperatively. No patients were discharged from the hospital on antiseizure medication. Comment The use of DHCA has played an important role in the development of successful operations to treat neonates and infants with critical congenital heart disease. As survival continues to improve, there has been an increased awareness of the potential neurologic morbidity associated with the use of DHCA. Recently, the use of low-flow CPB has been shown to yield improved results with respect to neurologic outcome compared with DHCA in clinical [1, 2] and animal studies [4, 5]. Although most intracardiac repairs can be performed safely and accurately without DHCA, its use is still predominant for aortic arch reconstruction. Interest has grown in recent years in a number of investigators to develop techniques for reconstructing the aortic arch while limiting the period of DHCA or eliminating DHCA altogether [6 13, 15]. Asou and associates [9] described two techniques of selective cerebral perfusion during aortic arch repair in neonates undergoing the Norwood operation for hypo-

Ann Thorac Surg TCHERVENKOV ET AL 2001;72:1615 20 NEONATAL AORTIC ARCH RECONSTRUCTION 1619 plastic left heart syndrome. The first technique involved perfusion of the innominate artery through an arterial cannula attached to the open end of a modified MBTS, after construction of the proximal anastomosis. The second technique involved direct cannulation of the innominate artery with a thin-walled metal cannula. Ishino and associates [11] have recently described their techniques for single-stage repair of aortic coarctation with ventricular septal defect using techniques for isolated cerebral and myocardial perfusion. One approach perfused the innominate artery from an arterial cannula inserted into the open end of a temporary polytetrafluoroethylene graft sewn to the innominate artery. Another approach used by this group was similar to our technique number 3 with a clamp placed just distal to the innominate artery while the distal arch was reconstructed. McElhinney and associates [12] maintained continuous upper body perfusion while performing a modified Damus Kaye Stansel procedure by cannulating the base of the innominate artery rather than using the MBTS. Others have cannulated both the MBTS and the descending thoracic aorta above the diaphragm, through a sternotomy approach to perfuse the upper and lower body during reconstruction of the aortic arch [10]. Pigula and colleagues [7] have also used an arterial cannula inserted into the open end of the MBTS to allow LFCP during reconstruction of the aortic arch. Although their technique was similar to those we described above, they used near infrared spectroscopy to characterize the cerebral blood volume and cerebral oxygen saturations during periods of LFCP. They found that a flow of 20 ml kg 1 min 1 was adequate in restoring cerebral blood volume and oxygen saturation at 18 C. At The Montreal Children s Hospital we have been able to consistently apply three techniques of LFCP, all of which avoid direct arch vessel cannulation and DHCA, for a wide variety of cardiac malformations requiring concomitant aortic arch reconstruction. When the ascending aorta is large enough to cannulate directly, we have used a technique of continuous LFCP through an arterial cannula advanced into the innominate artery (technique 1). This technique is straightforward and reproducible and the cannula has not impeded the extent to which we are able to augment the aortic arch. In a most challenging situation, such as the Norwood operation, we have developed a technique of retrograde flow through the MBTS into the innominate artery to maintain LFCP (technique 2) [6]. The MBTS is fully constructed before cannulation for CPB. This technique has reduced CPB time, avoided DHCA completely, and prevented any tension or inadvertent traction on the proximal end of the MBTS. The long, flexible arterial cannula inserted into the PDA has not impeded exposure of the arch during reconstruction. Using these techniques, we have been able to avoid both direct cannulation of the innominate artery and the construction of temporary grafts, each of which carries the risk of causing arterial stenoses in the future. Although we have been able to use these techniques of LFCP in a wide variety of cardiac malformations, we have not yet had the opportunity to use them in patients with interrupted aortic arch. The frequently diminutive ascending aorta, the use of two arterial cannulas, and the necessity for a direct anastomosis over a significant distance between the descending aorta and the small ascending aorta may present a particular technical challenge for any technique of LFCP. During periods of LFCP, we have used flows of 0.3 to 1.0 L min 1 m 2. When converted to the units used by Pigula and colleagues [7], our low-flow perfusion was maintained between 18 to 76 ml kg 1 min 1 (mean 44 ml kg 1 min 1 ), suggesting adequate cerebral circulatory support. In our study, the lowest oxygen saturation of the blood returning to the venous side of the CPB circuit was nearly 80%. This blood was drained from both the inferior and superior vena cavas and suggests adequate oxygen delivery to upper and lower body during LFCP. It may have been useful to separate the venous cannulas to measure the difference in the venous saturations between the inferior and superior vena cavas during LFCP and we intend to do this in the future. We have observed that LFCP through the innominate artery results in a significant amount of blood flow to the lower body through collaterals. Although this is only a subjective observation, we have found that removing the crossclamp on the descending aorta during our arch reconstruction resulted in flooding of the field immediately with blood, with the sole source of perfusion being the innominate artery. Pigula and associates [15] recently quantified the significant circulatory support that regional cerebral perfusion provides below the diaphragm. In summary, neonatal aortic arch reconstruction can be performed on a consistent basis using several techniques of LFCP with a low morbidity and mortality, avoiding DHCA or direct arch vessel cannulation. Continuous LFCP maintained adequate mixed-venous oxygen saturations with no associated adverse neurologic events. These techniques can be applied successfully in a wide variety of intracardiac repairs, including the Norwood operation. Further follow-up and a greater experience are required to determine the long-term impact of these techniques on neurodevelopmental outcomes. References 1. Newburger JW, Jonas RA, Wernovsky G, et al. A comparison of the perioperative neurologic effects of hypothermic circulatory arrest versus low-flow cardiopulmonary bypass in infant heart surgery. N Engl J Med 1993;329:1057 64. 2. Bellinger DC, Jonas RA, Rappaport LA, et al. Developmental and neurologic status of children after heart surgery with hypothermic circulatory arrest or low-flow cardiopulmonary bypass. N Engl J Med 1995;332:549 55. 3. Hickey P. Neurologic sequelae associated with deep hypothermia circulatory arrest. Ann Thorac Surg 1998;65:S65 70. 4. Swain JA, McDonald TJ, Griffith PK, et al. Low-flow hypothermic cardiopulmonary bypass protects the brain. J Thorac Cardiovasc Surg 1991;102:76 84. 5. Sakurada T, Kazui T, Tanaka H, Komatsu S. Comparative experimental study of cerebral protection during aortic arch reconstruction. Ann Thorac Surg 1996;61:1348 54. 6. Tchervenkov CI, Chu VF, Shum-Tim D, Laliberte E, Reyes TU. 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1620 TCHERVENKOV ET AL Ann Thorac Surg NEONATAL AORTIC ARCH RECONSTRUCTION 2001;72:1615 20 7. Pigula FA, Nemoto EM, Griffith BP, Siewers RD. Regional low-flow perfusion provides cerebral circulatory support during neonatal aortic arch reconstruction. J Thorac Cardiovasc Surg 2000;119:331 9. 8. Van Haaren NJCW, Bennick GBWE, de Vries JW. Pitfalls in neonatal cardiac surgery using antegrade cerebral perfusion. J Thorac Cardiovasc Surg 2001;121:184 6. 9. Asou T, Kado H, Imoto Y, et al. Selective cerebral perfusion technique during aortic arch repair in neonates. Ann Thorac Surg 1996;61:1546 8. 10. Imoto Y, Kado H, Shiokawa Y, Fukae K, Yasui H. Norwood procedure without circulatory arrest. Ann Thorac Surg 1999; 68:559 61. 11. Ishino K, Kawada M, Irie H, Kino K, Sano S. Single-stage repair of aortic coarctation with ventricular septal defect using isolated cerebral and myocardial perfusion. Eur J Cardiothorac Surg 2000;17:538 42. 12. McElhinney DB, Reddy VM, Silverman NH, Hanley FL. Modified Damus Kaye Stansel procedure for single ventricle, subaortic stenosis, and arch obstruction in neonates, and infants: midterm results and techniques for avoiding circulatory arrest. J Thorac Cardiovasc Surg 1997;114:718 26. 13. Karl TR, Sano S, Brawn W, Mee RB. Repair of hypoplastic or interrupted aortic arch via sternotomy. J Thorac Cardiovasc Surg 1992;104:688 95. 14. Tchervenkov CI, Tahta SA, Cecere R, Béland MJ. Singlestage arterial switch with aortic arch enlargement for transposition complexes with aortic arch obstruction. Ann Thorac Surg 1997;64:1776 81. 15. Pigula FA, Gandhi S, Siewers RD, Davis PJ, Webber SA, Nemoto EM. Regional low flow perfusion provides subdiaphragmatic circulatory support during neonatal aortic arch surgery. Ann Thorac Surg 2001;72:401 7.