Andersons pediatric cardiology 1058

Incidence Common arterial trunk is a rare anomaly Within the state of Texas, the prevalence of nonsyndromic common arterial trunk was 0.035 per 1000 live births, with a significant increase in the risk occurring with advancing maternal age and maternal residence near the border between Texas and Mexico.1 Extracardiac abnormalities are common in these patients Of 554 patients with common arterial trunk entered in the database of the Society of Thoracic Surgeons, 204 had some associated noncardiac abnormality, genetic abnormality, or a generalized syndrome.2 The incidence of congenital malformations of the heart is known to be increased in the offspring of patients with common arterial trunk, being 6.6% in the offspring of those with uncomplicated lesions and 13.6% of those with complex forms of the condition.3 Anatomy Of all the congenital lesions that benefit from being described in a straightforward fashion, common arterial trunk is the most obvious When described in terms of “truncus,” which is a poorly defined embryologic term, it is always necessary to provide a subsequent definition of the lesion as seen in the postnatal heart Describing the entity as a common arterial trunk negates the need for further definition (Fig 40.1) Almost always, the common ventriculoarterial junction is guarded by a common arterial valve Rare cases have now been described in which the common valve is divided into separate orifices for the right and left ventricles, with the raphe between the valvar orifices bound down to the crest of the ventricular septum so that shunting takes place at arterial level.4 The pattern of branching of the common trunk itself can be complicated by various arrangements of the individual arteries within the systemic, pulmonary, and coronary arterial circulations The presence of the common trunk, nonetheless, distinguishes the entity from patients having doubly committed ventricular septal defects, in which, although separate aortic and pulmonary valvar orifices are found within a common ventriculoarterial junction, the shunting is confined at ventricular level It also distinguishes the lesions from the “close cousins” in which there is a window between the intrapericardial components of the aorta and pulmonary trunk, and also those patients in which a large patent trunk leaves the base of the heart in company with an atretic trunk, which can itself be traced from its origin at the ventricular mass However, one variant that can still give problems in terms of description is when there is complete absence of the intrapericardial pulmonary arteries Collett and Edwards5 included this variant as the so-called type IV within their overall grouping However, the trunk arising from the ventricular mass in this setting is best described as a solitary, rather than a common, trunk This is because there is no way of knowing, had they been present, whether the intrapericardial pulmonary arteries would have originated from the arterial trunk or from the right ventricular outflow tract (Fig 40.2) In terms of clinical presentation and treatment, such patients with a solitary arterial trunk have more affinities with tetralogy and pulmonary atresia (see Chapter 36) than with common arterial trunk FIG 40.1 Common arterial trunk exiting from the ventricular mass through a common ventriculoarterial junction guarded by a common arterial valve and supplying directly the coronary, systemic, and pulmonary circulations FIG 40.2 Had the pulmonary arteries been present in the hearts illustrated, they could have arisen either from the heart (A) or from the arterial trunk itself (B) Therefore there is no way of knowing whether the trunk itself was destined to become an aorta or a common trunk Because of this uncertainty, it is best described as a solitary trunk However, patients with this arrangement are best considered as a subset of those with tetralogy and pulmonary atresia