Ann Thorac Surg 2005;79:1758-1760
© 2005 The Society of Thoracic Surgeons
Case report
Aortic Atresia and Type B Interrupted Aortic Arch: Diagnosis by Physiologic Cerebral Monitoring
Daniel J. DiBardino, MD*,a,
Jeffrey S. Heinle, MDa,
Dean A. Andropoulos, MDb,
Caroline D. Kerr,
David L. S. Morales, MDa,
Charles D. Fraser, Jr, MDa
a Division of Congenital Heart Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
b Division of Pediatric Cardiac Anesthesia, Department of Anesthesia, Baylor College of Medicine, Houston, Texas, USA
Accepted for publication November 19, 2003.
* Address reprint requests to Dr DiBardino, Division of Congenital Heart Surgery, Texas Children's Hospital, 6621 Fannin St, MC WT 19345H, Houston, TX 77030, USA
djd{at}bcm.tmc.edu
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Abstract
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Physiologic cerebral monitoring has become an important part of our cardiovascular surgical unit. We recently encountered an unusual variant of aortic atresia that was first suggested by physiologic cerebral monitoring and required modification of our operative technique. We describe and discuss the anatomy, its translation into cerebral monitor findings, and how we modified our operative technique.
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Introduction
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Hypoplastic left heart syndrome remains the most common congenital cardiac defect causing death in the neonatal period [1]. Underdevelopment of the left ventricle-aorta complex is the critical anatomic component of hypoplastic left heart syndrome, but it can also be accompanied by a highly variable degree of left-sided structural hypoplasia. For example, in the presence of a ventricular septal defect, aortic atresia may coexist with a well-developed left ventricle [2]. Since 1995, we have utilized the Norwood staged palliation for the treatment of hypoplastic left heart syndrome with improving results. Our preferred strategy is to provide regional low-flow cerebral perfusion during aortic reconstruction under the guidance of physiologic cerebral monitoring, including transcranial Doppler of the middle cerebral artery (MCA) and near-infrared spectroscopy [3]. We recently encountered an unusual variant of aortic atresia that was first suggested by cerebral monitoring and required modification of our operative technique.
A 38-week gestation neonate (weight, 2,895 g) presented with an echocardiographic diagnosis of an hypoplastic left heart syndrome variant including aortic atresia, severe aortic arch hypoplasia, a large ventricular septal defect, and a mildly hypoplastic left ventricle. The child was put forward for stage I palliation with the anticipation of eventual promotion to biventricular repair. At the induction of anesthesia, a right-sided transcranial Doppler probe was placed and the tracing was found to be consistent with retrograde blood flow in the MCA (Fig 1A). After median sternotomy, the patient was found to have aortic atresia, a severely hypoplastic aortic arch with type B interruption, hypoplastic carotid arteries, and a retroesophageal aberrant right subclavian artery. The ductus arteriosus and right atrium were cannulated, cardiopulmonary bypass was established, and the patient was cooled to 17°C. On visual inspection with the heart decompressed, it was clear that the flow in both common carotid arteries was retrograde (Fig 2). Norwood stage I reconstruction was performed under deep hypothermic circulatory arrest utilizing a generous patch of pulmonary artery homograft and incorporating repair of the interrupted arch. A 5-mm conduit was placed from the right ventricular outflow tract to the pulmonary artery bifurcation. The right-sided transcranial Doppler signal after repair demonstrated a bi-phasic tracing with a large positive deflection, indicative of normal pro-grade flow in the MCA (Fig 1B). The child made an uneventful recovery.
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Fig 1. (A) Transcranial Doppler tracing from the right middle cerebral artery at the induction of anesthesia. Note the predominately negative deflection denoting flow away from the transducer (retrograde flow). (B) Transcranial Doppler tracing from the right middle cerebral artery after the Norwood operation, and repair of the interrupted aortic arch. This pattern is consistent with a normal tracing in which a bi-phasic signal with a large positive deflection signifies flow toward the cranially placed transducer (pro-grade flow).
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Fig 2. Schematic illustration of the findings at operation, including aortic atresia, severely hypoplastic aortic arch with type B interruption, hypoplastic carotid arteries, and retroesophageal aberrant right subclavian artery. Arrows denote the direction of blood flow. Note the circle of Willis dependent coronary blood flow derived exclusively from the vertebral vessels.
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Comment
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Beginning in the year 2000, we have used regional low-flow cerebral perfusion and intraoperative cerebral monitoring during operations requiring aortic arch reconstruction [3]. Our preferred sequence is to initiate repair with the construction the systemic end of a right modified Blalock-Taussig shunt. By cannulating this shunt, we can initiate full-flow cardiopulmonary bypass, and by snaring the arch vessels, we can provide low-flow regional cerebral perfusion (50 mL/kg/min) during aortic arch reconstruction. At the conclusion of the operation the graft is decannulated, trimmed, and anastomosed to the right pulmonary artery to complete the right modified Blalock-Taussig shunt. The unexpected anatomy found at this operation made right modified Blalock-Taussig shunt construction impossible and necessitated the use of deep hypothermic circulatory arrest. Norwood first described the use of a right-ventricle to pulmonary artery conduit during stage 1 palliation of hypoplastic left heart syndrome in 1981 [4]. Although most subsequent experiences were performed by using a right modified Blalock-Taussig shunt to provide pulmonary blood flow, concerns for myocardial perfusion have led to a recent resurgence of the right-ventricle to pulmonary artery conduit configuration [5, 6].
We use cerebral monitoring routinely for patients undergoing cardiovascular surgery, including transcranial Doppler of the MCA and near-infrared spectroscopy. A normal MCA Doppler tracing consists of a bi-phasic signal with a large positive deflection signifying pro-grade flow toward the cranially placed transducer (Fig 1B). Although this patient was recognized to have an abnormal preoperative Doppler signal immediately upon transducer placement, this aberrancy was unexplained because the diagnosis of type B interrupted aortic arch and the resultant retrograde carotid artery flow was not known. The overall flow pattern resulted in bilateral retrograde carotid artery flow and a circle of Willis dependent coronary artery circulation supplied exclusively by the vertebral arteries. The predominately negative deflection in Figure 1A is indicative of retrograde flow in the right MCA, consistent with the anatomic findings at operation.
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References
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- Ashburn DA, McCrindle BW, Tchervenkov CI, et al. Outcomes after the Norwood operation in neonates with critical aortic stenosis or aortic valve atresia. J Thorac Cardiovasc Surg. 2003;125:1070–1082[Abstract/Free Full Text]
- Norwood WI, Stellin GJ. Aortic atresia with interrupted aortic arch: reparative approach. J Thorac Cardiovasc Surg. 1981;81:239–244[Abstract]
- Androupolous D, Stayer S, McKenzie ED, Fraser CD Jr. Novel cerebral monitoring to guide low-flow cerebral perfusion during neonatal arch reconstruction. J Thorac Cardiovasc Surg. 2003;125:491–499[Abstract/Free Full Text]
- Norwood WI, Lang P, Castaneda AR, Campbell DN. Experience with operations for hypoplastic left heart syndrome. J Thorac Cardiovasc Surg. 1981;82:511–519[Abstract]
- Sadahiro S, Kado H. Alternative procedure of modified Norwood operation for hypoplastic left heart syndrome. Circulation. 2002;106:3423
- Sano S, Ishino K, Kawada M, et al. Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg. 2003;126:504–510[Abstract/Free Full Text]
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Abstract
Introduction
