Non-confluent pulmonary arteries in a patient with pulmonary atresia and intact ventricular septum: ? A 5th aortic arch with a systemic-to-pulmonary arterial connection

Persistent fifth aortic arch: the "great pretender" in clinical practice

Persistence of the embryonic "fifth aortic arch" in postnatal life is a rare, enigmatic - and at times controversial - condition, with variable anatomical forms and physiological consequences. First described in humans over 40 years ago by Van Praagh, the condition was labelled the "great pretender" by Gerlis 25 years later, because of its apparent propensity to mimic anatomically similar structures. Despite many subsequent case reports citing the condition, the true developmental origin of these structures remains unresolved, and has been the subject of debate among embryologists for more than a century. A persistent fifth aortic arch has been defined as an extrapericardial structure, arising from the ascending aorta opposite or proximal to the brachiocephalic artery, and terminating in the dorsal aorta or pulmonary arteries via a persistently patent arterial duct. This description may therefore encompass various anatomical forms, such as a unilateral double-lumen aortic arch, an unrestrictive aortopulmonary shunt, or a critical vascular channel for either the systemic or pulmonary circulation. The physiological properties of these vessels, such as their response to prostaglandins, may also be unpredictable. In this article, we demonstrate a number of cases that fulfil the contemporary definition of "persistent fifth aortic arch" while acknowledging the embryological controversies associated with this term. We also outline the key diagnostic features, particularly with respect to the use of new cross-sectional imaging techniques.

Echocardiographic diagnosis of persistent fifth aortic arch

We describe echocardiography and computerized tomographic imaging findings in the two subtypes of fifth aortic arch in infants. In the first form, the fifth aortic arch creates a systemic to systemic connection extending from the ascending to the descending aorta. When this form appears in isolation, it does not cause hemodynamic disturbance, although associated cardiac lesions, such as aortic coarctation or interruption and patent ductus arteriosus, may influence the clinical presentation. In the second form the fifth aortic arch connects the systemic and pulmonary circulations from persistent connections between the embryological fifth and sixth arches, which may cause significant hemodynamic disturbance from left to right shunting. Although this form has been associated with a wide array of congenital cardiac lesions, this is the first description of 5th aortic arch in association with atrioventricular septal defect and double outlet right ventricle.

Isolated left pulmonary artery: Interventional stenting of a persistent fifth aortic arch

A few cases of isolated pulmonary artery have been successfully palliated by stenting the arterial duct using coronary stents. However, progressive luminal narrowing within the stent due to neointimal proliferation and peal formation is a considerable problem. We report the successful interventional palliation in a 7-week-old infant with isolated left pulmonary artery using sirolimus-eluting stents. In this unusual case, the isolated pulmonary artery was supplied by a duct-like remnant of a persistent fifth aortic arch, whereby the distal part of this vessel showed severe constriction. Implantation of two sirolimus-eluting coronary stents re-established good perfusion of the left pulmonary artery. Seven months after the procedure, echocardiography revealed that perfusion of the stented vessel and the left pulmonary artery was still very good. Stents eluting antimitotic agents also help to preserve the patency of small vessels in infants, and may be useful for ductal stenting.

Major aorto-pulmonary collateral arteries (MAPCAs)--Bronchial fistula presenting as tracheotomy bleed

Tracheal hemorrhage is a common occurrence in pediatric patients with long-term tracheotomies. The majority of these events are related to self-limited etiologies, such as granulation tissue or suction trauma. Tracheo-arterial fistula, however, represents a frequently fatal form of tracheal hemorrhage that may initially be difficult to distinguish from other causes. Previous reports have described the pathophysiology, presentation and management of tracheo-arterial fistula involving the innominate artery. We describe a case of a 21-month-old male with a history of significant congenital cardiac malformations and chronic tracheotomy tube dependence who presented with intermittent, brisk bleeding from the tracheotomy tube. He was ultimately diagnosed with and treated for an arterio-bronchial fistula from a major aorto-pulmonary collateral artery. We review the etiology and management of this disorder.

Pulmonary atresia with intact ventricular septum and systemic-pulmonary collateral arteries

Pulmonary atresia with intact ventricular septum and major systemic-pulmonary collateral arteries is a very rare congenital heart lesion with dismal natural history. Herein we report on a case of pulmonary atresia with intact ventricular septum with hypoplastic right ventricle, very small confluent pulmonary arteries, absent arterial duct, and pulmonary blood flow exclusively provided by bronchial-type systemic-pulmonary collateral arteries that was successfully treated at our institution.