Ann Thorac Surg 1997;64:1808-1810
© 1997 The Society of Thoracic Surgeons
Case Report
Truncus Arteriosus With Patent Ductus Arteriosus and Normal Aortic Arch
Dennis M. Mello, MD,
Doff B. McElhinney, MS,
Andrew J. Parry, MD,
Norman H. Silverman, MD,
Frank L. Hanley, MD
Divisions of Cardiothoracic Surgery and Pediatric Cardiology, University of California, San Francisco, San Francisco, California
Accepted for publication July 14, 1997.
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Abstract
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In hearts with a common arterial trunk (truncus arterios us), there is almost always an inverse development of the aortic arch and the ductus arteriosus. Truncus with a normal aortic arch and a patent ductus is a rare echocardiographic and surgical finding. In this report, we describe 2 neonates in whom truncus arteriosus with a normal aortic arch and a medium or large patent ductus was diagnosed by preoperative echocardiography (without catheterization) and confirmed intraoperatively.
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Introduction
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In their 1965 report, the Van Praaghs [1] observed an inverse development of the fourth and sixth pharyngeal arches in hearts with a common arterial trunk. In specimens with a well-developed aortic arch (fourth arch derivative), the ductus arteriosus (sixth arch derivative) was nearly always absent, whereas when a large patent ductus was present, the aortic arch was interrupted. This inverse relationship has been explained on the basis of blood flow patterns in the developing heart and truncus [2]. Although hemodynamics in utero most likely contribute to this pattern, a more fundamental defect in neural crest development or migration is almost certainly involved as well. This is supported by the association of both truncus arteriosus and interrupted aortic arch with microdeletions of chromosome 22q11 [3, 4], and by the high incidence of truncus arteriosus produced by ablating the neural crest region that contributes to the development of the fourth arch in chicks [5]. There have been several reports of truncus arteriosus with a well-developed fourth arch and a patent ductus in autopsy studies [1, 6, 7], although the ductus in these cases has generally been small. In clinical series of truncus repair, there has been little mention of this finding, and it is generally known to be the case that truncus with a normal aortic arch and a patent ductus is a rare echocardiographic and surgical finding [8–10].
Between July 1992 and December 1996, primary complete repair of truncus arteriosus was performed in 30 neonates at our institution. In 2 of these patients with truncus arteriosus and a normal aortic arch, the unusual finding of a medium-sized or large patent ductus along with a normal aortic arch was observed on preoperative echocardiography (without catheterization) and confirmed intraoperatively. These cases are presented below.
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Case Reports
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Patient 1
The patient presented on the second day of life with respiratory distress and was diagnosed to have truncus arteriosus by echocardiography. Prostaglandins were not administered. When the patient arrived at our institution, repeat echocardiography demonstrated a typical truncus arteriosus, with normal-sized pulmonary arteries originating from the posterior aspect of the common trunk. Arising from the central left pulmonary artery, at the point of separation between the ascending aorta and pulmonary artery, a large ductus was visualized.
At 17 days of age the patient was taken to the operating room. The heart was exposed through a median sternotomy, and it was immediately observed that there was a very large patent ductus arteriosus with an intact, unobstructed aortic arch and a common arterial trunk. The left pulmonary artery and the ductus arose from the left side of the truncal root and the right pulmonary artery originated from the posterior aspect of the trunk. At the institution of bypass, the ductus was ligated and the branch pulmonary arteries were clamped. After cardioplegic arrest, a large posterior patch of truncal tissue was excised to remove the pulmonary arteries in continuity along with the ductus arteriosus, which was then divided. All ductal tissue was trimmed from the pulmonary artery patch and sent for histopathologic evaluation, and the tissue was confirmed to be ductus arteriosus. The defect in the truncal root was closed with autologous pericardium. A standard truncus repair was then performed [10], with patch closure of the ventricular septal defect through a right ventriculotomy and establishment of right ventricle to pulmonary artery continuity using a 14-mm valved aortic allograft.
The hospital stay was uncomplicated and the patient was doing well at follow-up 10 months later, with evidence of mild pulmonary artery stenosis and only trivial conduit insufficiency. Balloon dilation was performed 7 months postoperatively for moderate pulmonary artery stenosis at the distal conduit anastomosis.
Patient 2
The patient was a 2,000-g neonate who was diagnosed on the first day of life with truncus arteriosus. When the patient arrived at our institution, echocardiography (off prostaglandins) demonstrated the typical findings of truncus arteriosus, with branch pulmonary arteries originating from the main pulmonary artery segment off the common trunk (Fig 1
). There was approximately 50% right ventricular override of the truncal root, and a large ventricular septal defect. The unusual finding of a patent ductus running from the pulmonary artery to its usual insertion site at the isthmus of the arch was also seen.
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Fig 1. . Preoperative echocardiogram in patient 2. (A) Subcostal coronal view showing the common trunk (T) overriding the ventricular septum. The division of the truncus into the ascending aorta (A) and the pulmonary artery (P) is shown. (B) Subcostal coronal view with more posterior angulation than in frame (A) shows the right (R) and left (L) pulmonary arteries arising from the pulmonary trunk. (C) Sagittal view from the high parasternal window demonstrating a large patent ductus arteriosus (D) continuing into the descending aorta (DAO), the ascending aorta (A), and the left pulmonary artery (L) running posterior to the common trunk just distal to its origin. (D) A coronal view from the high parasternal window shows the ductus arising at the point of origin of the left pulmonary artery. (LV = left ventricle; RA = right atrium; RV = right ventricle.)
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Operation was performed when the patient was 7 days of age. After exposure of the heart through a median sternotomy, the great vessels were examined and the pattern of truncus arteriosus was confirmed. In addition, there was a moderate-sized ductus arteriosus and a normal aortic arch. The ductus was divided, after which bypass was instituted with ascending aortic and bicaval cannulation. A standard technique of truncus repair was employed. During cooling, the pulmonary trunk arising from the truncus was transected and the aortic stump was oversewn primarily. The typical ventricular septal defect was closed through a right ventriculotomy, and a 10-mm valved aortic allograft was used to reconstruct the right ventricular outflow tract.
Postoperatively the patient has done well. Echocardiography 7 months after the operation showed good function, no residual defects, and trivial conduit insufficiency.
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Comment
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The Van Praaghs' observation [1] that the development of the fourth and sixth embryonic arches is inversely related in the setting of a common arterial trunk is well recognized. Although the hemodynamic consequences of a common arterial outflow may predispose to the development of either the fourth or sixth arch but not both [2], it is likely that anomalous development of the arch system is a fundamental aspect of the morphogenetic anomalies that produce truncus arteriosus [3–5]. In most cases of truncus the ductus is absent altogether, and although the presence of a ligamentous remnant or a small patent ductus has been described in several necropsy series [1, 6, 7], it is a rare echocardiographic or surgical finding. In the present series, we have reported 2 neonates with truncus arteriosus and the unusual finding of a moderate to large patent ductus along with a well-developed fourth arch. From a surgical perspective, this rarity is easily managed with simple ligation and division of the ductus. From a diagnostic standpoint, however, it is conceivable that this finding could pose problems. For example, retrograde flow in the descending aorta, which is a reliable Doppler finding in patent ductus, is also typically present in patients with truncus arteriosus. Similarly, there is unlikely to be systolic ductal shunting in a patient with truncus unless the left pulmonary artery is stenotic proximal to the ductal take-off. Another consideration is that a ductus is nearly always present in cases of aortopulmonary septal defect [7], which might potentially be confused with truncus arteriosus if the defect is large and the semilunar valves and outflow tract are poorly imaged. Such a scenario is unlikely, but it does underscore the importance of recognizing that a patent ductus can occur in conjunction with both aortopulmonary septal defects and truncus arteriosus, and that the rarity of this finding should not blind the echocardiographer to its presence.
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Footnotes
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Address reprint requests to Dr Mello, 505 Parnassus Avenue, M593, San Francisco, CA 94143-0118.
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References
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- Van Praagh R, Van Praagh S. The anatomy of common aorticopulmonary trunk (truncus arteriosus communis) and its embryologic implications: a study of 57 necropsy cases. Am J Cardiol 1965;16:406–25.[Medline]
- Rothko K, Moore GW, Hutchins GM. Truncus arteriosus malformation: a spectrum including fourth and sixth arch interruptions. Am Heart J 1980;99:17–24.[Medline]
- Van Mierop LHS, Kutsche LM. Cardiovascular anomalies in DiGeorge syndrome and importance of neural crest as a possible pathogenetic factor. Am J Cardiol 1986;58:133–7.[Medline]
- Goldmuntz E, Driscoll D, Budarf ML, et al. Microdeletions of chromosomal region 22q11 in patients with congenital conotruncal cardiac defects. J Med Genet 1993;30:807–12.[Abstract/Free Full Text]
- Nishibatake M, Kirby ML, Van Mierop LHS. Pathogenesis of persistent truncus arteriosus and dextroposed aorta in the chick embryo after neural crest ablation. Circulation 1987;75:255–64.[Abstract/Free Full Text]
- Bharati S, Lev M. The pathology of congenital heart disease: a personal experience with more than 6,300 congenitally malformed hearts. Armonk, NY: Futura, 1996:353–80.
- Gerlis LM, MacGregor CCd'A, Ho SY. An anatomical study of 110 cases with deficiency of the aorticopulmonary septum with emphasis on the role of the arterial duct. Cardiol Young 1992;2:342–52.
- Kirklin JW, Barratt-Boyes BG. Truncus arteriosus. In: Kirklin JW, Barratt-Boyes BG, eds. Cardiac surgery. New York: John Wiley & Sons, 1992:1131–51.
- Di Donato RM, Fyfe DA, Puga FJ, et al. Fifteen-year experience with surgical repair of truncus arteriosus. J Thorac Cardiovasc Surg 1985;89:414–22.[Abstract]
- Hanley FL, Heinemann MK, Jonas RA, et al. Repair of truncus arteriosus in the neonate. J Thorac Cardiovasc Surg 1993;105:1047–56.[Abstract]
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Abstract
Introduction
