Ann Thorac Surg 2006;81:1126-1127
© 2006 The Society of Thoracic Surgeons
Case report
The Right-Sided Window Ductus: A Rare Anatomical Entity
Vladimiro L. Vida, MD
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Oscar Veras, MD,
Juan Leon-Wyss, MD,
Ivan Vides, MD,
Aldo R. Castañeda, MD, PhD
Unidad de Cirugia Cardiovascular de Guatemala (UNICAR), Guatemala Ciudad, Guatemala
Accepted for publication January 17, 2005.
* Address correspondence to Dr Vida, Unidad de Cirugia Cardiovascular de Guatemala (UNICAR), 9 Avenida, 8-00, Zona 11, Guatemala Ciudad, Guatemala (Email: vladimirovida{at}interfree.it).
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Abstract
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A rare type of patent ductus arteriosus called window ductus was identified in association with a right aortic arch in a 1-year-old child who was referred for closure of a membranous ventricular septal defect.
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Introduction
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Surgical repair included preoperative bypass division of the window ductus followed by patch closure of the ventricular septal defect. The window ductus is a wide but short patent ductus arteriosus, not easily identified on external inspection. This structure can be confused with a very distal aortopulmonary window. Because of its rarity, the potential for preoperative misdiagnosis is great, and precise intraoperative understanding of this anatomical entity is essential for the correct surgical treatment.
The window ductus (WD) is a wide and very short patent ductus arteriosus (PDA) that is not apparent on external inspection, and is diagnostically and surgically challenging [1–3]. When the WD is associated with a right-sided aortic arch it represents a rare anatomical entity as described in this case.
A 1-year-old female infant had a preoperative echocardiographic diagnosis of a single large membranous ventricular septal defect.
At surgery, in addition to the ventricular septal defect we found a right aortic arch; a mirror-image branching pattern of the brachiocephalic vessels; a right-sided descending aorta; and a wide, short, and unrestrictive communication (2 cm) between the proximal right aortic arch and the main pulmonary artery, immediately distal to the bifurcation of the right and left pulmonary artery branches.
The main pulmonary artery (MPA) appeared to be continuous with the aortic arch, resembling a single large artery. The first left brachiocephalic vessel (or left innominate artery), arose from this anomalous vascular communication (Fig 1). The vascular communication was carefully dissected from the surrounding tissue and was temporarily occluded with a vascular clamp. Because there were no hemodynamic changes, before instituting cardiopulmonary bypass, the communication was clamped on both the aortic and pulmonary sides, just distal to the bifurcation of the pulmonary arteries, and was subsequently divided and sutured. In this way, the left innominate artery was left originating from the aortic arch (Fig 2). The operation also included a trans-atrial pericardial patch closure of the ventricular septal defect using moderately hypothermic cardiopulmonary bypass. The patient was easily weaned from cardiopulmonary bypass, was in regular sinus rhythm, and had stable hemodynamics. She was extubated in the operating room. Two hours later in the intensive care unit, the patient had to be reintubated for respiratory failure due to atelectasis of the entire left lung. On postoperative day 5, the patient was successfully extubated. The postoperative echocardiogram revealed no residual intracardiac or extracardiac shunts and an estimated pressure in the right ventricle was 85 mm Hg. The patient was discharged home in stable clinical condition and on oral sildenafil (0.5 mg/kg), because of the residual pulmonary hypertension. At 1-month follow-up, the estimated pressure in the right ventricle by echocardiography had decreased to aproximatively 20 mm Hg, and the sildenafil was consequently discontinued.
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Fig 1. Diagram demonstrating the preoperative surgical anatomy. The cross-hatched area shows the site of the window-ductus. (A = aorta; LIA = left innominate artery; LPA = left pulmonary artery; MPA = main pulmonary artery; RAA = right aortic arch; RCA = right carotid artery; RPA = right pulmonary artery; RSA = right subclavian artery.)
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Fig 2. Diagram showing the postoperative surgical anatomy. (A = aorta; LIA = left innominate artery; LPA = left pulmonary artery; MPA = main pulmonary artery; RAA = right aortic arch; RCA = right carotid artery; RPA = right pulmonary artery; RSA = right subclavian artery.)
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Comment
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This anomalous vascular communication represents a rare and atypical PDA called WD. The WD is a wide, short, and unrestrictive PDA that is confusing on external inspection, resembling a very distal aortopulmonary window. When the WD is associated with a left aortic arch, the MPA appears directly continuous with the descending thoracic aorta, resembling a single large artery with no visible interposed ductus [1–3]. In this case, the WD was associated with a right aortic arch and a right descending aorta. The MPA appeared directly continuous with the aortic arch, sharing the origin of the left brachiocephalic artery.
Embryologically and anatomically the MPA cannot truly be confluent with the aorta above its level of bifurcation despite its external appearance. The only way for the MPA to be confluent with the aorta is through a PDA [4]. Consequently, this wide-open aortopulmonary communication, despite its appearance, cannot be considered an aortopulmonary window because of its location distal to the bifurcation of the pulmonary arteries [4].
On internal inspection, the wall of the WD does not really resemble a PDA; rather it resembles the wall of an elastic artery, similar to the MPA or the aorta, presenting few or no intimal pads, little or no encircling or lassoing medial musculature with little or no luminal narrowing. Histologically however, the WD has been reported to contain ductal intimal pads and ductal medial musculature, confirming that this wide aortopulmonary communication is indeed a very large PDA [2]. In this patient, after division of the WD, its vascular wall did not appear thickened or constricted. However, due to its shortness, we could not obtain a sufficiently large histological sample of the vascular wall to confirm this data.
We believe that in the past [1–3] only three similar cases have been reported all presenting a WD in association with a left aortic arch. In all three cases the WD was recognized only at postmortem examination.
We are presenting the first patient with a right-sided WD in association with a right aortic arch and mirror-image branching of the brachiocephalic vessels and a right-sided descending aorta. In this patient, the WD was correctly diagnosed in the operating room and underwent successful surgical division without the use of cardiopulmonary bypass, prior to closure of the ventricular septal defect. The WD can often prove confusing both diagnostically and surgically; the potential for a preoperative misdiagnosis is great, and a precise intraoperative understanding of this anatomical entity is necessary to reach the correct surgical solution. Surgical division and suture of the WD can be accomplished safely without cardiopulmonary bypass and offers a valid alternative to a previously proposed intravascular patch closure of the WD stoma [2–3].
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Acknowledgments
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We thank Dr Richard Van Praagh for his help in increasing our understanding of the embryo-pathology of this rare entity.
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References
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- Lev M. Autopsy of congenitally malformed hearts. Springfield: Charles C Thomas; 1953. pp. 130.
- Grunenfelder J, Bartram U, Van Praagh R, et al. The large window ductusa surgical trap. Ann Thorac Surg 1998;65:1790-1791.[Abstract/Free Full Text]
- Komeda M, Miki S, Kusuhara K, et al. Report of a case of an atypical patent ductus arteriosus Kyobu Geda 1989;42:35-39.
- Kutsche LM, Van Mierop LHS. Anatomy and patho-genesis for aortopulmonary septal defectanalysis of 286 reported cases. Am J Cardiol 1897;59:443-447.
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Abstract
Introduction
