LAUSR

There remain many controversies across the spectrum of congenital cardiology which are not limited to rare diagnoses and uncommonly preformed procedures. Factors contributing to this include a paucity of randomized trials, the heterogeneous nature of congenital cardiac disease (even within each headline diagnosis), differences health care systems offering care and an enthusiasm to carry out new procedures, often related to morbidity and mortality associated with current strategies. A natural and useful way of addressing and discussing these controversies is as part of debate sessions at speciality meetings. Although these are often delivered by experts within that area the total audience is often limited to those attending the meeting. The purpose of this Research Topic was to extend this debate to print allowing review of more detailed argument and data presented by the experts to a wider audience. The three topics considered in this Research Topic are the pulmonary valve replacement for pulmonary valve regurgitation, the current role of echocardiography in the diagnosis of congenital heart defects, and the best modality of cardiopulmonary bypass for pediatric heart surgery. In developed health care systems pulmonary valve replacement is the third most common procedure in congenital cardiology after atrial septal defect closure and patent ductus arteriosus closure. Between 2014 and 2017 1,039 such procedures were carried out in the UK (260 in children and 779 in adults) of which 803 were surgical and 260 transluminal with a reported 30 daymortality for either procedure of <1%1. Given that this is a high frequency low mortality procedure debate as to the most appropriate option must also explore morbidity and long term outcomes from the procedure. In this edition Morgan and Corno present the controversy surrounding whether pulmonary valve regurgitation should be addressed surgically or interventionally from the point of view of the interventional cardiologist and the cardiac surgeon. Morgan explores the rapid developments in both the technique and technology in the field of percutaneous pulmonary valve implantation. Previous perceived limitations of the procedure and how these are being addressed are explored. In particular techniques used in the presence of small right ventricular outflow tracts, including hybrid techniques, and large outflow tracts, including stents to build landing zones for valve implantation, developments of valve technology to fill the redundant space, and use of a branch pulmonary artery to secure the some types of valve. The latest available models of percutaneously implantable valves are described in detail, with potential advantages and disadvantages to orient the readers in the choice (Morgan). Finally in the discussion the potential drawbacks and complications are thoroughly analyzed. Specific procedural complications are discussed including the possibility of conduit rupture, valve embolization,