Introduction The various abnormal ventriculoarterial connections, such as transposition in its regular or congenitally corrected variants, double-outlet ventricles, and common arterial trunk, are all congenital malformations involving the ventricular outflow tract They are often described in terms of “conotruncal malformations,” but this term is poorly defined As currently used, it rarely includes lesions of the arterial valves, which are also components of the ventricular outflow tracts All these lesions, along with pulmonary and aortic atresia, have been discussed at length in this text However, several additional lesions, all of which involve different parts of the outflow tracts, are best described in a separate chapter Therefore this chapter discusses aortopulmonary (AP) windows, anomalous origin of one pulmonary artery (PA) from the intrapericardial aorta, aortoventricular tunnels, and aneurysms of the aortic sinuses of Valsalva Also discussed is the rare situation of either duplication of an outflow tract or the even more rare variant of duplication of the aortic root This chapter begins with a reprise of the normal anatomy of the outflow tracts It is axiomatic that the abnormal arrangements cannot properly be appreciated without full understanding of the normal situation Until recently, it was difficult to provide rational explanations for the development of all the normal components, apart from seeking to explain the morphogenesis of the malformations The ability to illustrate with accuracy the temporal development of the outflow tracts, as already described in Chapter 3, now makes it possible to suggest reasons why the outflow tracts should develop abnormally in such a way as to produce the various lesions Therefore the chapter includes a recapitulation of the steps involved in normal separation of the initially common outflow tract into the separate outlets for the right and left ventricles, the arterial roots, and the intrapericardial arterial trunks These changes are related to the postnatal anatomy of the various lesions as a prelude to describing their clinical features Anatomy of the Intrapericardial Outflow Tracts As discussed earlier, it has been conventional to describe both the development and the morphology of the outflow tracts in terms of the truncus and conus This approach has proven less than satisfactory, largely because it ignores the arterial roots, which occupy a significant length within the middle of both outflow tracts (Fig 51.1A and D) FIG 51.1 Dissections of normal hearts showing features of the intrapericardial outflow tracts (A) Section prepared to replicate the oblique subcostal echocardiographic cut It shows how the pulmonary outflow tract is made up of the infundibulum, the pulmonary root, and the pulmonary trunk, the latter branching at the margins of the pericardial cavity (arrows) into the right and left pulmonary arteries Note that the pulmonary outflow tract is almost at right angles to the aortic root, which is cut in short axis (B) Short axis cut across the intrapericardial arterial trunks, demonstrating that each possesses its own discrete walls (C) Short axis of the aortic root viewed from above The pulmonary outflow tract has been reflected forward to show the space between the aortic and pulmonary roots (dashed line) Note the extensive muscular subpulmonary infundibulum (D) Cut replicating the parasternal long-axis echocardiographic projection It shows that the space between the roots (as shown in C) continues proximally to separate the subpulmonary infundibulum from the aortic root It also shows the three components of the aortic outflow tract Note that the nonadjacent sinus of the aortic root is in fibrous continuity with the aortic