Ann Thorac Surg 2000;70:2147-2149
© 2000 The Society of Thoracic Surgeons
Case report
Precoronary stenosis after stage I palliation for hypoplastic left heart syndrome
Mustafa H. Abdullah, MBBCha,b,c,
Glen S. Van Arsdell, MDa,b,c,
Lisa K. Hornberger, MDa,b,c,
Ian Adatia, MBChBa,b,c
a Divisions of Cardiology and Cardiovascular Surgery, The Toronto Hospital for Sick Children, Toronto, Ontario, Canada
b Departments of Critical Care Medicine, Surgery, and Pediatrics, The Toronto Hospital for Sick Children, Toronto, Ontario, Canada
c University of Toronto, Toronto, Ontario, Canada
Accepted for publication May 18, 2000.
Address reprint requests to Dr Adatia, Critical Care Medicine and Cardiology, The Hospital For Sick Children, Toronto, ON, M5G 1X8, Canada
e-mail: ian.adatia{at}sickkids.on.ca
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Abstract
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We report a patient with stenosis of the native ascending aorta after palliation of hypoplastic left heart syndrome and aortic atresia. We describe the approach to diagnosis, temporary support with extracorporeal membrane oxygenation, and successful surgical reintervention. Stenosis of the native ascending aorta is an important, potentially reversible cause of acute, early postoperative ventricular dysfunction.
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Introduction
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It is distinctly unusual to detect a remediable anatomic cause for acute early ventricular dysfunction after a modified Norwood stage I operation for hypoplastic left heart syndrome. Therefore, we present a case of native ascending aorta obstruction following Brawn’s modification of aortic reconstruction in aortic atresia [1]. Early diagnosis, temporary mechanical extracorporeal support, and surgical revision all contributed to a successful outcome.
A term infant with a birth weight of 3.3 kg and a prenatal diagnosis of hypoplastic left heart syndrome was referred to our institution for a surgical staged palliation. The patient was stable, receiving prostaglandin infusion and a hypoxic gas mixture without lactic acidosis at any time before the operation.
Postnatal two-dimensional echocardiography demonstrated aortic and mitral atresia with a hypoplastic left ventricle and juxtaductal coarctation of the aorta. The ascending aorta measured 2 mm and the transverse arch 2 mm. There was no tricuspid or pulmonary valve regurgitation and the ventricular function was normal.
On day 3 of life a Norwood stage I procedure using Brawn’s modification [1] for aortic arch reconstruction was performed together with an atrial septectomy and insertion of a 3.5-mm polytetrafluoroethylene tube graft (Gore-Tex; W.L. Gore and Assoc, Flagstaff, AZ) between the innominate artery and the right pulmonary artery. Upon completion of the operation, the infant returned from the operating room with the sternum open but the skin closed. The patient had a serum lactate concentration of 3 mmol/L and required minimal inotropic support.
Over the next 12 hours, the serum lactate and inotropic requirements increased. An echocardiographic evaluation revealed reduced ventricular function, and severe tricuspid and neoaortic valve regurgitation. The aortic arch was unobstructed, and the modified Blalock-Taussig (B-T) shunt appeared patent without stenosis. Color flow Doppler demonstrated aliasing at the proximal end of the native ascending aorta (Fig 1). In addition, a spectral pulsed Doppler interrogation of the native ascending aorta revealed a continuous flow pattern with a mean gradient of 11 mm Hg (which reflects the coronary perfusion pressure).
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Fig 1. Color flow Doppler aliasing at the site of obstruction in the native ascending aorta. (Cx = circumflex artery; LAD = left anterior descending artery; N-Ao = neoaorta.
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We elected to resuscitate and stabilize the patient with extracorporeal membrane oxygenation (ECMO). The sternum was opened and the neoaorta cannulated with an 8F RMI aortic cannula (Edwards Life Sciences, Ontario, Canada). The right atrial appendage was cannulated with an 18F Polystan right angle venous catheter (Ryan Medical Distributors, Ontario, Canada). The B-T shunt was clipped. We used a closed centrifugal pump system with a Carmeda-coated Minimax hollow fiber oxygenator (Medtronic Canada Ltd, Ontario, Canada) and a Biomedicus centrifugal pump (Medtronic Canada Ltd). We adjusted the flow rate between 90 to 140 mL · kg-1 · min-1 and maintained mean arterial blood pressure at less than 40 mm Hg. We administered phenoxybenzamine to reduce systemic vascular resistance. Subsequent cardiac catheterization confirmed the diagnosis of proximal native ascending aorta obstruction (Fig 2).
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Fig 2. Angiogram of the neoaorta demonstrating precoronary stenosis at the junction of the native aorta ascending aorta with the neoaorta (Native Ao). The clip is placed on the right Blalock-Taussig shunt (double arrowhead) during extracorporeal membrane oxygenation (ECMO) support. (Cx = circumflex artery; DA = descending aorta; LAD = left anterior descending artery; LCCA = left common carotid artery; N-Ao = neoaorta; RCA = right coronary artery.)
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Following surgical reimplantation of the native ascending aorta, the ECMO support was discontinued successfully in the operating room. The patient was discharged on the 20th postoperative day with good ventricular function and mild tricuspid valve regurgitation and without neoaortic valve regurgitation. At 3 months of age the patient underwent a bidirectional superior cavopulmonary anastomosis and recovered uneventfully.
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Comment
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We have described native ascending aorta obstruction following a modified stage I Norwood in a neonate with aortic atresia and hypoplastic left heart syndrome. The patient had a successful outcome after surgical reintervention. The prompt and complete detection of the complications that may occur after first-stage palliation for hypoplastic left heart syndrome is important. Such complications may be life threatening or limit the suitability of the infant for a staged bidirectional Glenn anastomosis. Meliones and coworkers [2] reported the complications encountered after first- stage palliation. Although they noted that tricuspid valve regurgitation (13%), ventricular dysfunction (29%), neoaortic regurgitation (13%), and 58% of all deaths occurred within the first 24 hours because of cardiovascular collapse, they did not report native ascending aorta obstruction. Bartram and coworkers [3] studied 122 autopsy specimens and suggested that impaired coronary perfusion (27%) because of precoronary obstruction (ie, the native aortic root) was an important cause of death. They emphasized that fatal complications after the Norwood procedure were largely due to technical and surgically correctable lesions.
By necessity, in patients with aortic atresia, the native ascending aorta must be anastomosed to the neoaorta to maintain a conduit to the coronary arteries, analogous to a single coronary arterial supply [4]. The presence of mild obstruction coupled with the run-off to the pulmonary circulation through the B-T shunt may result in a tenuous coronary circulation. We speculate that coronary ischemia may underlie the observations that a small (2 mm or less) native ascending aorta and aortic atresia may be risk factors for early death after stage I palliation [5, 6].
Although the Doppler characteristics of native ascending aorta flow after stage I have been studied [7] there are no reports of precoronary Doppler flow patterns in patients with unexplained postoperative deterioration in ventricular function or new tricuspid valve regurgitation, despite autopsy data demonstrating obstruction to coronary perfusion after stage I.
Extracorporeal membrane oxygenation support is considered not to improve survival in patients with residual cardiac defects, especially palliated patients with single ventricle physiology [8]. However, our case suggests ECMO support is beneficial while undertaking a search for a surgically remediable problem.
In summary, early postoperative onset of ventricular dysfunction and tricuspid or neoaortic valve regurgitation should prompt a careful search for potentially remediable myocardial ischemia because of native ascending aorta or precoronary obstruction.
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References
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Bu’Lock F.A., Stümper O., Jagtap R., et al. Surgery for infants with a hypoplastic systemic ventricle and severe outflow obstruction: early results with a modified Norwood procedure. Br Heart J 1995;73:456-461.[Abstract/Free Full Text]
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Meliones J.N., Snider R., Bove E.L., Rosenthal A., Rosen D.A. Longitudinal results after first-stage palliation for hypoplastic left heart syndrome. Circulation 1990;82(Suppl IV):151-156.
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Bartram U., Grünenfelder J., Van Praagh R. Causes of death after the Norwood procedure: a study of 122 postmortem cases. Ann Thorac Surg 1997;64:1795-1802.[Abstract/Free Full Text]
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Norwood W.I., Lang P., Hansen D.D. Physiologic repair of aortic atresia-hypoplastic left heart syndrome. N Engl J Med 1983;308:23-26.[Medline]
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Forbess J.M., Cook N., Roth S.J., Serraf A., Mayer J.E., Jonas R.A. Ten-year institutional experience with palliative surgery for hypoplastic left heart syndrome—risk factors related to stage I mortality. Circulation 1995;92(Suppl II):II262-II266.
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Ishino K., Stümper O., De Giovanni J.V., et al. The modified Norwood procedure for hypoplastic left heart syndrome: early to intermediate results of 120 patients with particular reference to aortic arch repair. J Thorac Cardiovasc Surg 1999;117:920-930.[Abstract/Free Full Text]
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