Ann Thorac Surg 2007;84:1398-1399
© 2007 The Society of Thoracic Surgeons
Case Reports
Pediatric Coronary Artery Bypass After Arterial Switch Operation: Noninvasive Evaluation With ECG-Gated 64-Slice CT in Routine Practice
Monia Jemmali, MDa,
Davide Marini, MDa,
Giulio Calcagni, MDa,
Francis Brunelle, MDb,
Daniel Sidi, MD, PhDa,
Damien Bonnet, MD, PhDa,
Phalla Ou, MD, PhDb,*
a University Rene Descarte-Paris 5, Hôpital Necker-Enfants Malades, Department of Pediatric Cardiology, Paris, France
b University Rene Descartes-Paris 5, Hôpital Necker-Enfants Malades, Department of Pediatric Radiology, Paris, France
Accepted for publication May 29, 2007.
* Address correspondence to Dr Ou, Department of Pediatric Radiology, Hôpital Necker-Enfants Malades, 149, rue de Sèvres 75743 Paris, Cedex 15, France (Email: phalla.ou{at}nck.ap-hop-paris.fr).
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Abstract
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Coronary artery bypass is increasingly used as a revascularization procedure to treat pediatric coronary artery problems. We report here the clinical usefulness of high resolution computed tomographic scan in the evaluation of the internal mammary artery bypass graft in a 12-year-old child who had undergone arterial switch operation for transposition of the great arteries. Our case suggests the following practice already applied in our institution: 64-slice computed tomography can be used as a valuable noninvasive diagnostic and screening tool for detecting coronary and artery bypass graft complications in the follow-up of the arterial switch operation before having recourse to conventional angiography.
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Introduction
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Coronary artery bypass grafting (CABG) is a classic revascularization procedure used to treat pediatric coronary artery problems, as for example in the arterial switch operation [1], Kawasaki disease [2], or other iatrogenic lesions [3]. The availability of a noninvasive diagnostic tool to assess CABG could be of great clinical benefit in this setting. Our observation highlights the potential role of new generations of multislice computed tomography (CT) for evaluating the internal mammary artery bypass graft in a 12-year-old child who had undergone the arterial switch operation.
A 12-year-old child was admitted to our institution for atypical chest pain. He had undergone an arterial switch operation in the neonatal period for a transposition of the great arteries. Transfer of the coronary arteries had been particularly difficult because of the intramural course of the left coronary artery that had required bypass during the switch operation. The left internal mammary artery graft had been used to supply the left anterior descending coronary artery circulation.
At the present admission, the patient was asymptomatic. Resting electrocardiogram, exercise testing, and echocardiography were normal. We performed a cardiac-gated CT scanning by using a 64-slice CT scanner: thickness 0.625 mm; 100kV; mA modulated during the acquisition; peripheral injection of contrast agent (iomeprol 400, 80 mL injected at 3 mL/sec). A beta-blocker (propranolol 1 mg/kg) was given orally 2 hours before the examination. A CT acquisition lasted 5.3 seconds, and the examination lasted approximately 15 minutes in total.
A CT scan allowed perfect visualization of the left internal mammary artery graft that was anastomosed to the left anterior descending coronary artery. There was no stenosis at the anastomosis site (Fig 1). The right ostia raised normally from the right sinus; it gave a large right coronary artery and a retro-aortic circumflex artery (Fig 2).
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Fig 1. Computed tomographic angiography of the coronary artery bypass graft. Three-dimensional reconstruction (left panel) and curved multiplanar reconstruction (right panel) the left internal mammary artery jump graft to the left anterior descending coronary artery. The arrow marks the anastomotic site.
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Fig 2. Computed tomographic angiography of the right and circumflex coronary arteries. Three-dimensional reconstruction (left panel) and axial image with maximal intensity projection (right panel) showing a large right coronary artery (RCA) and a retro-aortic circumflex artery (Cx) that raise from a common right ostium. (Ao = aorta.)
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Comment
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Our observation demonstrates the clinical usefulness of 64-slice CT as a reliable and noninvasive diagnostic modality to evaluate CABG in the follow-up of children who had undergone coronary revascularization procedures. A CT coronary angiography can be made quicker with more safety, and it is less expensive than conventional invasive angiography. We believe that it should now be chosen as the noninvasive alternate method for examining the coronary circulation in children in this setting.
The number of operations comprising manipulations of the coronary arteries in children should lead to an increase of indications for evaluating CABG disease in the future [1–3]. Indeed these patients may be readmitted with unconvincing recurrent chest pain, as in our present case, and conventional coronary angiography is still the standard of reference for direct assessment of CABG status. However, as an invasive examination method, it is associated with a low but definite risk of complications and it may require hospitalization after arterial puncture as is usual in our practice. Concerns about procedure-related risks and cost consideration have motivated the development of noninvasive techniques to assess CABG, including CT and magnetic resonance imaging.
With the newest generation of CT scanners, both temporal and spatial resolutions are significantly improved. When performed adequately (using oral beta blockade and strict breath hold during image acquisitions), CT can be used for the detection of complete graft occlusion or graft patency of CABG in adults [4]. In children it is important to consider certain patient-related aspects for having satisfactory CT images. Good cooperation of the child is necessary, as acquisitions depend on breath holding for approximately 5 seconds to avoid respiratory motion artifact. In our experience, patient preparation is of importance and includes reassurance, sympathetic explanation, and brief training with breath holding maneuvers before the examination. Furthermore oral beta blockade is required and must be given 1 to 2 hours before the examination to ensure a stable heart rate less than 80 bpm. In this condition, coronary CT angiography is possible, and excellent image quality can be obtained in children older than 5 years of age.
Magnetic resonance imaging represents a totally noninvasive alternative for assessing CABG, avoiding ionizing radiation. However it is still hampered by a low spatial resolution and a long time scanning. Furthermore the importance of motion artifacts prohibits the reliable evaluation of the anastomotic sites [5]. Advances in hardware and software, as well as new contrast agents, will certainly improve image quality so that assessment of CABG by magnetic resonance imaging may permit an exciting alternative to conventional and CT coronary angiography in the future.
Our observation points out the emergent role of multislice CT as a reliable imaging modality in the evaluation of CABG and recipient vessels in children having undergone the coronary revascularization procedure. Such a noninvasive diagnostic tool is particularly useful in selected children with unconvincing symptoms, avoiding normal conventional invasive angiography. Indeed our case suggests the following practice already applied in our institution: 64-slice CT can be used as a valuable noninvasive diagnostic and screening tool for detecting coronary and artery bypass graft complications in the follow-up of the arterial switch operation before having recourse to conventional angiography.
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References
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- Ebels T, Meuzelaar K, Gallandat Huet RC, et al. Neonatal arterial switch operation complicated by intramural left coronary artery and treated by left internal mammary artery bypass graft J Thorac Cardiovasc Surg 1989;97:473-475.[Medline]
- Tsuda E, Kitamura S, Cooperative Study Group of Japan National survey of coronary artery bypass grafting for coronary stenosis caused by Kawasaki disease in Japan Circulation 2004;110(11 Suppl 1):II61-II66.[Medline]
- Mavroudis C, Backer CL, Duffy CE, Pahl E, Wax DF. Pediatric coronary artery bypass for Kawasaki congenital, post arterial switch, and iatrogenic lesions Ann Thorac Surg 1999;68:506-512.[Abstract/Free Full Text]
- Anders K, Baum U, Schmid M, et al. Coronary artery bypass graft (CABG) patency: assessment with high-resolution submillimeter 16-slice multidetector-row computed tomography (MDCT) versus coronary angiography Eur J Radiol 2006;57:336-344.[Medline]
- Bunce NH, Lorenz CH, John AS, Lesser JR, Mohiaddin RH, Pennell DJ. Coronary artery bypass graft patency: assessment with true fast imaging with steady-state precession versus gadolinium-enhanced MR angiography Radiology 2003;227:440-446.[Abstract/Free Full Text]
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Abstract
Introduction
