Ann Thorac Surg 1997;64:537-539
© 1997 The Society of Thoracic Surgeons
Case Reports
Bilateral Branch Pulmonary Artery Obstruction Due to Kinking at Insertion Sites of Bilateral Ductus Arteriosus
Doff B. McElhinney, MS,
V. Mohan Reddy, MD,
Phillip Moore, MD,
Frank L. Hanley, MD
Divisions of Cardiothoracic Surgery and Pediatric Cardiology, University of California, San Francisco, San Francisco, California
Accepted for publication March 19, 1997.
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Abstract
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Bilateral ductus arteriosus (or ligamentum arteriosum) with right aortic arch and isolation of the left subclavian artery is a rare anomaly of the aortic arch system. We report on a patient with complete atrioventricular septal defect, right aortic arch, bilateral ligamentum arteriosum, and isolation of the left subclavian artery in whom kinking at the ductal insertions caused bilateral branch pulmonary artery obstruction. Complete surgical repair was performed when the patient was 4 months of age, and the pulmonary artery obstructions were entirely relieved by ligation and division of both ducts without pulmonary arterioplasty.
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Introduction
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Bilateral ductus arteriosus (or ligamentum arteriosum) with right aortic arch and isolation of the left subclavian artery is a rare anomaly of the aortic arch system that most commonly occurs without associated cardiac defects or with conotruncal anomalies such as tetralogy of Fallot [1–3]. When branch pulmonary artery (PA) stenosis occurs at the site of ductus insertion, it is most likely due to one of two causes: extension of ductal tissue into the PA, causing juxtaductal coarctation [4], or dilatation of the pulmonary outflow tract due to high output or free pulmonary insufficiency, causing branch PA kinking and resultant obstruction at the fixed point of ductus (or ligamentum) insertion. Recently, we performed an operation on a patient with complete common atrioventricular septal defect, right aortic arch, bilateral ductus arteriosus, and isolation of the left subclavian artery, in whom kinking at the ductal insertions caused bilateral branch PA obstruction that was completely relieved by ligation and division of both ducts.
A patient with trisomy 21 underwent initial cardiac evaluation at 2 weeks of age after a heart murmur was detected. Echocardiographic evaluation revealed a Rastelli type A complete atrioventricular septal defect with a large inlet interventricular communication, a small ostium primum atrial defect, and mild left atrioventricular valvar regurgitation. Also seen were a large secundum atrial septal defect, a right aortic arch, and a retroaortic innominate vein. Severe bilateral branch PA stenosis was diagnosed on the basis of blood flow acceleration of 3 m/s into the right PA and 4 m/s into the left PA. Cardiac catheterization was performed when the patient was 2 months of age. An ascending aortogram revealed abnormal anatomy of the head and neck vessels, with only two arch vessels visualized and filling of the left subclavian artery via delayed, apparently retrograde, flow. No patent ductus was visualized on either aortic or PA injections, but ductus diverticula were observed on the underside of the aortic arch and on the superior portions of the proximal left and right branch PAs. Measurements taken from the main pulmonary arteriogram showed the stenotic segment of the left PA to be approximately 3 mm in diameter, whereas the diameter of the proximal right PA stenosis was 4 mm (both branches measured 5 mm distally), but did not clearly reveal kinking of the PAs (Fig 1
). There was a peak systolic gradient of 60 mm Hg into the left PA and 28 mm Hg into the right PA (Fig 2), which correlated well with the echocardiographic estimates. Indexed pulmonary blood flow was 6.3 L · min-1 · m-2, and the ratio of pulmonary to systemic blood flow was 2.1:1. On the basis of these data, it was determined that the gradients into the branch PAs may have been due in small part to elevated pulmonary blood flow, but were primarily the result of anatomic obstruction. Systolic and pulse pressures (by cuff measurement) were substantially lower in the left arm than in the right (see Fig 2).
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Fig 1. . (A) Main pulmonary arteriogram in the left lateral projection, demonstrating severe left branch pulmonary artery stenosis and a ductus diverticulum at the origin of the left branch pulmonary artery (arrow). Note that kinking of the left branch pulmonary artery is not readily apparent. (B) Anteroposterior right oblique projection from the same main pulmonary artery injection showing bilateral branch pulmonary artery obstruction, which does not appear to be due to kinking. Also note the left (open arrow) and right (arrowhead) ductus diverticula. For comparison, note the position of the catheter tip, indicated by the small straight arrow (although these frames are not simultaneous, they are from the same cardiac cycle, and there was very little migration of the catheter between them).
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Fig 2. . Schematic depiction of the anatomy of the great arteries and their branches. The kinking is exaggerated in this illustration, and is not intended to accurately represent the angiographic or surgical appearance. Pressures obtained at catheterization are listed for the main, left (LPA), and right (RPA) pulmonary arteries, as well as the aorta and both arms. (LCCA = left common carotid artery; LSCA = left subclavian artery; LVA = left vertebral artery; RCCA = right common carotid artery; RSCA = right subclavian artery.)
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At 4 months of age the patient was taken to the operating room. Upon exposure of the heart and great vessels, we observed that both common carotid arteries originated from a single branch of the arch. In addition, bilateral ductal remnants (ligamentums) were present: the right ductus ran from the underside of the right aortic arch to the proximal right PA, whereas the left ductus connected the proximal left PA to an isolated left subclavian artery (see Fig 2
). The left and right branch PAs were clearly kinked at the respective sites of ductal insertion. Both ligamentums were doubly ligated and divided. The pulmonary trunk was then opened and the branch PAs were explored. There was no intrinsic stenosis of either branch and no coarctation: the right PA easily accepted a 7-mm dilator and the left accepted a 5-mm dilator all the way out of the hilum. Thus, the obstruction was completely corrected with simple division of the bilateral ductus, which eliminated the tension on the PAs and relieved the kinking that caused the stenosis. The pulmonary arteriotomy was closed with no further PA intervention. After this, the atrioventricular septal defect was repaired through a right atriotomy using a single patch technique. After discontinuation of bypass, the systemic blood pressure was 75/40 mm Hg and right ventricular pressure was 35/2 mm Hg. Postbypass transesophageal echocardiography showed trivial left and right atrioventricular valvar insufficiency, no intracardiac shunting, and no PA stenosis. No thrills could be detected on palpation of the main and branch PAs.
The postoperative course was uneventful, and the patient was discharged on postoperative day 6. At follow-up of 15 months, the patient was thriving, with no evidence of PA stenosis or intracardiac shunting. Left arm blood pressures have been consistently lower than pressures in the right arm.
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Comment
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Bilateral ductus arteriosus (or ligamentum) is a rare anomaly that typically occurs in conjunction with a right aortic arch, with or without other associated arch anomalies, including double aortic arch, discontinuous central PAs, anomalous subclavian artery, or isolation of one or more brachiocephalic vessels [1, 3]. When bilateral ductus with isolation of the left subclavian artery occurs with intracardiac anomalies, such anomalies are most frequently those that have a high incidence of association with right aortic arch, such as tetralogy of Fallot (16%) [1, 2, 5]. Atrioventricular septal defects do not often occur with anomalies of the aortic arch system (with the exception of aortic coarctation) [5]. Similarly, retroaortic innominate vein, which was once thought to be extremely rare but is diagnosed more often now that its echocardiographic appearance has been well characterized, is known to occur in patients with a right aortic arch more frequently than in patients with normal aortic arch laterality [6].
Perhaps the most significant point of this case report is to emphasize the importance of recognizing the nature of branch PA stenosis to optimize therapy. The most likely causes in cases of discrete narrowing at the ductus insertion are kinking of the PA due to distortion around the fixed point of ductal insertion and coarctation resulting from the extension of ductal tissue into the PA [4]. In our experience, kinking usually occurs in the setting of right ventricular outflow tract dilatation or high pulmonary blood flow (unpublished data). On the other hand, coarctation is most common in patients with decreased right ventricular outflow (pulmonary stenosis or atresia), in whom left to right ductal shunting provides most or all pulmonary blood flow in intrauterine life. It may be difficult to determine the mechanism of obstruction on angiography or echocardiography (as was the case with our patient), but kinking can be clearly identified on direct visualization. The proper surgical management of stenosis due to PA kinking is removal of the distortion. In patients who have not had a previous operation, such as the patient described in the present report, simple division of the ductus (or ligamentum) may free the PA sufficiently to relieve the torsion at the point of ductal insertion. After this, the branch PAs must be explored to assess whether intrinsic stenosis is also present, in which case augmentation arterioplasty may be necessary. In our patient, exploration revealed no evidence of coarctation or intrinsic stenosis, and arterioplasty was not required. When the stenosis is due to juxtaductal coarctation, the coarcted segment of PA should be excised and the distal PA reanastomosed to the pulmonary trunk. If the coarctation is not severe, simple patch augmentation may be adequate. It is important to realize that when PA stenosis due only to kinking is treated with patch arterioplasty of the PA origin (without ductus division), the obstruction may recur, insofar as this approach adds redundant tissue without correcting the mechanism of obstruction. Recurrent stenosis may develop as the redundancy of the tissue (with or without dilatation of the patch segment) can serve as an impetus for further kinking due in part to an obstructive and distorting mass effect proximal to the ductus insertion. If properly recognized and treated, this mechanism of branch PA obstruction is easily corrected.
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Footnotes
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Address reprint requests to Dr Hanley, Division of Cardiothoracic Surgery, UCSF, 505 Parnassus Ave, M593, San Francisco, CA 94143-0118.
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References
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- Luetmer PH, Miller GM. Right aortic arch with isolation of the left subclavian artery: case report and review of the literature. Mayo Clin Proc 1990;65:407–13.[Medline]
- Victoria BE, Van Mierop LHS, Elliott LP. Right aortic arch associated with contralateral congenital subclavian steal syndrome. Am J Roentgenol 1970;108:582–90.[Abstract]
- Freedom RM, Moes CAF, Pelech A, et al. Bilateral ductus arteriosus (or remnant): an analysis of 27 patients. Am J Cardiol 1984;53:884–91.[Medline]
- Elzenga NJ, Suylen RJ, Frohn-Mulder I, Essed CE, Bos E, Quaegebeur JM. Juxtaductal pulmonary artery coarctation: an underestimated cause of branch pulmonary artery stenosis in patients with pulmonary atresia or stenosis and a ventricular septal defect. J Thorac Cardiovasc Surg 1990;100:416–24.[Abstract]
- Bharati S, Lev M. The pathology of congenital heart disease: a personal experience with more than 6,300 congenitally malformed hearts. Armonk, NY: Futura, 1996:67–133, 553–86.
- Choi JY, Jung MJ, Kim YH, Noh CI, Yun YS. Anomalous subaortic position of the brachiocephalic vein (innominate vein): an echocardiographic study. Br Heart J 1990;64:385–7.[Abstract/Free Full Text]
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Abstract
Introduction
